阅读说明：本技术 用于测试三维存储器设备的结构和方法 (Structure and method for testing three-dimensional memory devices ) 是由 金钟俊 潘锋 李钟硕 吕震宇 李勇娜 宋立东 金允哲 S·W·杨 S·S-N·杨 于 2018-03-01 设计创作，主要内容包括：公开了用于测试三维(3D)存储器设备的结构和方法。3D存储器设备(100)包括存储器阵列结构(102)、外围设备结构(104)、与存储器阵列结构(102)的正面和外围设备结构(104)的正面相接触的互连层(106)、以及位于存储器阵列结构(102)的背面并且与存储器阵列结构(102)重叠的导电衬垫。存储器阵列结构(102)包括存储器阵列堆叠(109)、垂直延伸穿过至少一部分存储器阵列堆叠(109)的贯穿阵列接触(TAC)(110)、以及存储器阵列接触(112)。外围设备结构(104)包括测试电路(126)。互连层(106)包括互连结构(116、124)。导电衬垫(108)、TAC(110)、互连结构(116、124)、以及测试电路(126)与存储器阵列接触(112)中的至少一者是电连接的。(Structures and methods for testing three-dimensional (3D) memory devices are disclosed. The 3D memory device (100) includes a memory array structure (102), a peripheral device structure (104), an interconnect layer (106) in contact with a front side of the memory array structure (102) and a front side of the peripheral device structure (104), and a conductive pad located at a back side of the memory array structure (102) and overlapping the memory array structure (102). The memory array structure (102) includes a memory array stack (109), a Through Array Contact (TAC) (110) extending vertically through at least a portion of the memory array stack (109), and a memory array contact (112). The peripheral device structure (104) includes a test circuit (126). The interconnect layer (106) includes an interconnect structure (116, 124). At least one of the conductive pads (108), the TACs (110), the interconnect structures (116, 124), and the test circuitry (126) are electrically connected with the memory array contacts (112).)

1. A memory device, comprising:

a memory array structure, comprising:

a memory array stack;

a through-array contact TAC extending vertically through at least a portion of the memory array stack; and

one or more memory array contacts;

a first dielectric layer on a front side of the memory array structure;

a plurality of first contacts in the first dielectric layer;

a plurality of conductive pads on a back side of the memory array structure;

a Complementary Metal Oxide Semiconductor (CMOS) structure;

a metal layer on a front side of the CMOS structure, the metal layer comprising a plurality of metal patterns;

a second dielectric layer on the metal layer; and

a plurality of second contacts in the second dielectric layer;

wherein the first and second dielectric layers are in contact with each other such that the memory array structure is over the CMOS structure and one or more electrical connections are formed at least by at least one of the plurality of conductive pads, the TAC, at least one of the plurality of first contacts, at least one of the plurality of second contacts, at least one of the plurality of metal patterns in the metal layer, and at least one of the one or more memory array contacts.

2. The memory device of claim 1, wherein at least one of the plurality of first contacts and at least one of the plurality of second contacts form a contact signal path.

3. The memory device of claim 2, wherein the one or more memory array contacts comprise at least one of a word line contact and a bit line contact.

4. The memory device of claim 3, wherein the plurality of conductive pads, the TAC, the plurality of first contacts, the plurality of second contacts, the plurality of metal patterns in the metal layer, and the word line are electrically connected to form a first electrical connection of the one or more electrical connections to test a plurality of contact signal paths.

5. The memory device of claim 3, wherein the plurality of conductive pads, the TAC, the plurality of first contacts, the plurality of second contacts, the plurality of metal patterns in the metal layer, and the bit lines are electrically connected to form a second electrical connection of the one or more electrical connections to test a plurality of contact signal paths.

6. The memory device of claim 4 or 5, wherein the plurality of contact signal paths are connected in series.

7. The memory device of claim 4 or 5, wherein at least some of the plurality of contact signal paths are connected in parallel.

8. The memory device of claim 7, wherein at least half of the plurality of contact signal paths are connected in parallel.

9. The memory device of any of claims 1 to 5 or 8, wherein the CMOS structure comprises: a test circuit electrically connected to the metal layer.

10. The memory device of claim 9, wherein the test circuitry comprises at least one of memory array structure test circuitry and contact signal path test circuitry.

11. The memory device of claim 10, wherein the memory array structure test circuitry comprises at least one of: memory plane test circuitry, memory block test circuitry, bit line test circuitry, and word line test circuitry.

12. The memory device of any of claims 1 to 5, 8, 10 or 11, wherein the memory array structure further comprises a third contact, wherein at least one of the plurality of conductive pads is electrically connected to the TAC through the third contact.

13. A method for forming a memory device, comprising:

forming a memory array structure comprising a memory array stack and one or more memory array contacts;

forming a through-array contact TAC that extends vertically through at least a portion of the memory array stack in the memory array structure;

forming a first dielectric layer on the front surface of the memory array structure;

forming a plurality of first contacts in the first dielectric layer;

forming a plurality of conductive pads on a back side of the memory array structure;

forming a complementary metal oxide semiconductor CMOS structure;

forming a metal layer on the front surface of the CMOS structure, wherein the metal layer comprises a plurality of metal patterns;

forming a second dielectric layer on the metal layer;

forming a plurality of second contacts in the second dielectric layer; and

the first and second dielectric layers are contacted to each other such that the memory array structure is over the CMOS structure and one or more electrical connections are formed at least by at least one of the plurality of conductive pads, the TAC, at least one of the plurality of first contacts, at least one of the plurality of second contacts, at least one of the plurality of metal patterns in the metal layer, and at least one of the one or more memory array contacts.

14. The method of claim 13, further comprising: forming a test circuit before forming a metal layer on the front side of the CMOS structure, wherein the metal layer is electrically connected to the test circuit.

15. The method of claim 13 or 14, further comprising forming a third contact from the backside of the memory array structure prior to forming a plurality of conductive pads on the backside of the memory array structure, wherein:

at least one of the plurality of conductive pads is electrically connected to the TAC through the third contact; and

the at least one of the plurality of conductive pads is formed over the third contact.

16. A three-dimensional (3D) memory device, comprising:

a memory array structure, comprising:

a memory array stack;

a first through array contact TAC extending vertically through at least a portion of the memory array stack; and

a memory array contact;

a peripheral device structure including a test circuit;

an interconnect layer in contact with a front side of the memory array structure and a front side of the peripheral device structure, the interconnect layer comprising an interconnect structure; and

a first conductive pad on a backside of the memory array structure and overlapping the memory array structure;

wherein the first conductive pad is electrically connected through the first TAC, the interconnect structure, and at least one of the test circuitry and the memory array contacts.

17. The memory device of claim 16, further comprising:

a second conductive pad on the backside of the memory array structure and overlapping the memory array structure; and

a second TAC extending vertically through at least a portion of the memory array stack,

wherein the first and second conductive pads are electrically connected by the at least one of the first TAC, the second TAC, the interconnect structure, and the test circuitry and the memory array contacts.

18. The memory device of claim 17, wherein the first and second conductive pads are electrically connected through the first TAC, the second TAC, the interconnect structure, and the memory array contact.

19. The memory device of claim 17, wherein the first and second conductive pads are electrically connected through the first TAC, the second TAC, the interconnect structure, and the test circuit.

20. The memory device of claim 17, wherein the first and second conductive pads are electrically connected through the first TAC, the second TAC, the interconnect structure, and the memory array contact, and the test circuit.

21. The memory device of any one of claims 16 to 20, wherein a distance in a vertical direction between the first conductive pad and the memory array stack is at least about 3 μ ι η.

22. The memory device of any one of claims 16 to 20, wherein the interconnect layer comprises a hybrid bonding interface.

23. The memory device of any one of claims 17 to 20, wherein the first and second conductive pads have nominally the same size and nominally the same shape.

24. The memory device of any of claims 16 to 20, wherein the memory array contact comprises at least one of: a word line contact, a bit line contact, and a select gate contact.

Technical Field

Embodiments of the present disclosure relate to a three-dimensional (3D) memory device and a method of testing the same.

Background

Through improvements in process technology, circuit design, programming algorithms, and manufacturing methods, planar memory cells can be scaled to smaller dimensions. However, as the feature size of memory cells approaches the lower limit, planar processes and fabrication techniques become challenging and costly. As a result, the memory density of the planar memory cell approaches the upper limit.

The 3D memory architecture may address the density limitations of planar memory cells. The 3D memory architecture includes a memory array and peripherals, where the peripherals are used to control signals to and from the memory array.

Disclosure of Invention

Embodiments of the present disclosure disclose structures of three-dimensional (3D) memory devices and methods for testing 3D memory devices.

According to some embodiments of the present disclosure, a memory device includes a memory array structure, a first dielectric layer on a front side of the memory array structure, a plurality of first contacts in the first dielectric layer, a plurality of conductive pads on a back side of the memory array structure, a Complementary Metal Oxide Semiconductor (CMOS) structure, a metal layer comprising a plurality of metal patterns on the front side of the CMOS structure, a second dielectric layer on the metal layer, and a plurality of second contacts in the second dielectric layer. The memory array structure includes a memory array stack, a Through Array Contact (TAC) extending vertically through at least a portion of the memory array stack, and one or more memory array contacts. The first and second dielectric layers are connected face-to-face such that the memory array structure is over a CMOS structure and one or more electrical connections are formed of at least one of the plurality of conductive pads, the TAC, the plurality of first contacts, the plurality of second contacts, a plurality of metal patterns in the metal layer, and the one or more memory array contacts.

In some embodiments, at least one of the plurality of first contacts and at least one of the plurality of second contacts form a contact signal path. The one or more memory array contacts may include at least one of a word line contact and a bit line contact. The plurality of conductive pads, the TAC, the plurality of first contacts, the plurality of second contacts, the plurality of metal patterns in the metal layer, and the word line may be electrically connected to form a first electrical connection of the one or more electrical connections for testing a plurality of contact signal paths. The plurality of conductive pads, the TAC, the plurality of first contacts, the plurality of second contacts, the plurality of metal patterns in the metal layer, and the bit line contacts may be electrically connected to form a second electrical connection of the one or more electrical connections to test a plurality of contact signal paths. In some embodiments, the plurality of contact signal paths are connected in series. In some embodiments, at least a portion of the plurality of contact signal paths are connected in parallel. For example, half of the plurality of contact signal paths may be connected in parallel.

In some embodiments, the CMOS structure includes a test circuit electrically connected to the metal layer. The test circuit may include at least one of a memory array structure test circuit and a contact signal path test circuit. The memory array structure test circuit may include at least one of a memory plane test circuit, a memory block test circuit, a bit line test circuit, and a word line test circuit.

In some embodiments, the memory array structure further comprises a third contact (e.g., a Through Silicon Via (TSV)). At least one of the plurality of conductive pads may be electrically connected to the TAC through the third contact.

According to some embodiments of the present disclosure, a method of forming a memory device is disclosed. A memory array structure including a memory array stack and one or more memory array contacts is first formed. A Through Array Contact (TAC) is then formed that extends vertically through at least a portion of the memory array stack of the memory array structure. A first dielectric layer is formed on the front surface of the memory array structure. A plurality of first contacts are formed in the first dielectric layer. A plurality of conductive pads are formed on a backside of the memory array structure. A Complementary Metal Oxide Semiconductor (CMOS) structure is formed. A metal layer including a plurality of metal patterns is formed on a front surface of the CMOS structure. And forming a second dielectric layer on the metal layer. Forming a plurality of second contacts in the second dielectric layer. Connecting the first and second dielectric layers face-to-face such that the memory array structure is over the CMOS structure and forming one or more electrical connections made of at least one of the plurality of conductive pads, the TAC, the plurality of first contacts, the plurality of second contacts, a plurality of metal patterns in the metal layer, and the one or more memory array contacts.

In some embodiments, a test circuit is formed prior to forming the metal layer on the front side of the CMOS structure. The metal layer may be electrically connected to the test circuit.

In some embodiments, a third contact (e.g., a TSV) is formed on the back side of the memory array structure before the plurality of conductive pads are formed on the back side of the memory array structure. At least one of the plurality of conductive pads may be electrically connected to the TAC through the third contact. The at least one of the plurality of conductive pads may be formed over a third contact.

According to some embodiments of the present disclosure, a method for testing a memory device is disclosed. The memory device includes a memory array structure, a first dielectric layer on a front side of the memory array structure, a plurality of first contacts in the first dielectric layer, a plurality of conductive pads on a back side of the memory array structure, a Complementary Metal Oxide Semiconductor (CMOS) structure, a metal layer comprising a plurality of metal patterns on the front side of the CMOS structure, a second dielectric layer on the metal layer, and a plurality of second contacts in the second dielectric layer. The memory array structure includes a memory array stack, a Through Array Contact (TAC) extending vertically through at least a portion of the memory array stack, and one or more memory array contacts. An input signal is received for testing a test structure in a memory device. The input signal is transmitted to the test structure through a first probe and a first electrical connection, the first electrical connection including one of the plurality of conductive pads, one of the plurality of TACs, one of the plurality of first contacts, one of the plurality of second contacts, one of the plurality of metal patterns in the metal layer, and at least one of the one or more memory array contacts. Receiving an output signal from the test structure through a second probe and a second electrical connection, the second electrical connection including one of the plurality of conductive pads, one of the plurality of TACs, one of the plurality of first contacts, one of the plurality of second contacts, one of the plurality of metal patterns in the metal layer, and at least one of the one or more memory array contacts. Determining a characteristic of the test structure in the memory device based on the input signal, the output signal, and the test structure.

In some embodiments, the test structure comprises at least one of a contact signal path and a structure of the memory array structure, the contact signal path comprising at least one of the plurality of first contacts and at least one of the plurality of second contacts.

Drawings

The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate embodiments of the present disclosure and, together with the detailed description, further serve to explain the principles of the disclosure and to enable a person skilled in the pertinent art to make and use the disclosure.

Fig. 1 is a cross-sectional schematic diagram of an exemplary 3D memory device shown in accordance with some embodiments of the present disclosure.

Fig. 2 is a top view of an exemplary 3D memory device shown in accordance with some embodiments of the present disclosure.

FIG. 3 is a schematic diagram of an exemplary test structure illustrating a set of contact signal paths in accordance with some embodiments of the present disclosure.

FIG. 4 is a schematic diagram of another test structure illustrating a set of contact signal paths according to some embodiments of the present disclosure.

Fig. 5 is a flow chart illustrating an exemplary method for forming a 3D memory device in accordance with some embodiments of the present disclosure.

FIG. 6 is a flow chart illustrating an exemplary method for testing a 3D memory device in accordance with some embodiments of the present disclosure.

Fig. 7A-7J illustrate exemplary fabrication methods for forming a 3D memory device, in accordance with some embodiments of the present disclosure.

Embodiments of the present disclosure will be described below with reference to the accompanying drawings.

Detailed Description

Although specific structures and configurations are discussed herein, it should be understood that this is done for purposes of illustration and example only. It should be understood by those skilled in the relevant art that other structures and arrangements can be used without departing from the spirit and scope of the disclosure. It will be apparent to those skilled in the relevant art that the present disclosure may also be used in a variety of other applications.

It is worthy to note that references in the specification to "one embodiment," "an example embodiment," "some embodiments," etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic, and such references do not necessarily refer to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the relevant art to effect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

In general, terminology may be understood, at least in part, based on the context of usage. For example, the term "one or more" as used herein may be used in the singular to describe any feature, structure, or characteristic, or may be used to describe a plural combination of features, structures, or characteristics, depending at least in part on the context. Similarly, terms such as "a," "an," or "the" may also be understood to convey a singular use or to convey a plural use, which may depend, at least in part, on the context. Moreover, the term "based on" may be understood as a set of factors that are not necessarily intended to convey exclusivity, and may instead allow for the presence of additional factors that are not necessarily expressly described, and that depend, at least in part, on context.

It should be readily understood that the meaning of "above," "over," and "over" herein should be interpreted in the broadest manner, such that "above" not only means "directly on something," but also includes on something with an intervening feature or layer therebetween, and "above" or "over" not only means on something or over something, but also may include the meaning without an intervening feature or layer therebetween (i.e., directly on something).

Furthermore, spatially relative terms, such as "under", "lower", "over", "higher", and the like, may be used in the description to describe one element or feature's relationship to another element or feature for ease of description, as illustrated in the figures. These spatially relative terms are intended to encompass different orientations or directions of the device in use or operation in addition to the orientation depicted in the figures. The device may be otherwise oriented (e.g., rotated 90 degrees or at other orientations) and the spatially relative descriptors used in the specification interpreted accordingly.

As used herein, the term "substrate" refers to a material upon which a subsequent layer of material is added. The substrate itself may be patterned. The material added on top of the substrate may be patterned or may remain unpatterned. In addition, the substrate may include a variety of semiconductor materials, such as silicon, germanium, gallium arsenide, indium phosphide, and the like. Alternatively, the substrate may be made of a non-conductive material, such as glass, plastic, or sapphire wafers.

As used herein, the term "layer" refers to a portion of material, a region of which has a thickness. The extent of one layer may extend over the entire underlying or overlying structure, or it may be less than the extent of the underlying or overlying structure. In addition, a layer may be a region of uniform or non-uniform continuous structure, which may have a thickness less than the thickness of the continuous structure. For example, a layer may be located between the top and bottom surfaces of the continuous structure or between any pair of horizontal planes between the top and bottom surfaces of the continuous structure. The layers may extend horizontally, vertically, and/or along the tapered surface. The substrate may be a layer, which may include one or more layers, and/or may have one or more layers above and/or below it. One layer may comprise multiple layers. For example, the interconnect layer may include one or more conductor and contact layers (in which contacts, interconnect lines, and/or vias are formed) and one or more dielectric layers.

The term "nominal" as used herein refers to a desired value or target value, and a range of values above and/or below the desired value, of a characteristic or parameter of a component or process operation set during the design time of the product or process. The numerical ranges may vary slightly due to manufacturing processes or tolerances. The term "about" as used herein refers to a given quantitative value that may vary depending on the particular technology point associated with the subject semiconductor device. Based on the particular point of skill, the term "about" can indicate a given quantitative value, e.g., varying by within 10-30% of the value (e.g., ± 10%, ± 20% or ± 30% of the value).

The term "3D memory device" as used herein refers to a semiconductor component having vertically oriented strings of memory cell transistors (referred to herein as "memory strings," such as NAND strings) on a laterally oriented substrate such that the memory strings extend in a vertical direction relative to the substrate. As used herein, the term "vertical" means nominally perpendicular to a lateral surface of a substrate.

In some 3D memory devices, the peripheral and memory array components may be stacked on top of each other. However, until now, there has been no effective method of testing the performance of the internal structure of the 3D memory device using a probe card before packaging the 3D memory device.

Embodiments in accordance with the present disclosure provide 3D memory devices having structures for testing 3D memory devices. The 3D memory devices disclosed herein may include an interconnect layer having an interconnect structure between the frontside of stacked peripheral device structures (e.g., CMOS chips) and memory array structures (e.g., memory array chips) and contacting a through-array contact (TAC) of the memory array structures. The 3D memory device disclosed herein may further include conductive pads for a probe card located on the back side of the memory array structure, such that various characteristics of different structures of the 3D memory device and the quality of the hybrid bonding process to form the 3D memory may be tested through a probe card with a true component density. Accordingly, the 3D memory device disclosed herein may enable testability and consistency of characteristics of the 3D memory device formed by hybrid bonding of the peripheral device structure and the memory array structure, thereby reducing overall process development time and improving manufacturing yield.

Fig. 1 is a cross-sectional schematic diagram of an exemplary 3D memory device 100 shown in accordance with some embodiments of the present disclosure. As shown in fig. 1, the 3D memory device 100 may include a memory array structure 102 and a peripheral structure 104 (e.g., CMOS structure) that are placed face-to-face, facing each other. As used herein, the term "front side" of a structure (e.g., memory array structure 102 or peripheral structure 104) refers to a side of the structure (e.g., memory cells in memory array structure 102 or peripheral transistors in peripheral structure 104) that forms a component. Conversely, the term "back side" as used herein refers to a side of a structure (e.g., memory array structure 102 or peripheral device structure 104) opposite the front side.

As shown in fig. 1, the 3D memory device 100 may include an interconnect layer 106 between the memory array structure 102 and the peripheral device structure 104 in a vertical direction (e.g., the y-direction or thickness direction as shown in fig. 1). Interconnect layer 106 may be in contact with the front side of memory array structure 102 and the front side of peripheral device structure 104. The 3D memory device 100 may also include a plurality of conductive pads 108 (e.g., solder pads or landing pads) located on the back side of the memory array structure 102 and electrically connected to the memory array structure 102, the interconnect layer 106, and the peripheral device structure 104. In some embodiments, the conductive pads 108 are disposed on a top surface of the 3D memory device 100, i.e., over the memory array structure 102 and the peripheral device structure 104.

In some embodiments, memory array structure 102 includes a memory array stack 109 in a memory array area. Memory array stack 109 can be formed on the front side of a substrate (not shown) and can include alternating conductor/dielectric stacks and an array of NAND strings extending through the alternating conductor/dielectric stacks. The alternating conductor/dielectric stack may include alternating conductor layers (e.g., metal layers or polysilicon layers) and dielectric layers (e.g., silicon oxide layers or silicon nitride layers). Each NAND string can include a plurality of vertically stacked memory cells, with each memory cell being controlled by a respective conductor layer (acting as a control gate) surrounding alternating conductor/dielectric stacks of the NAND string. The conductor layers in the alternating conductor/dielectric stack may extend in a lateral direction (e.g., the x-direction or width direction as shown in fig. 1) outside of the memory array region, forming word lines of the memory array structure 102. Each NAND string may also include a drain at one end (e.g., on the front side of the memory array structure 102). The drains of each NAND string can be electrically connected to a respective one of a plurality of bit lines of the memory array structure 102. In some embodiments, each NAND string also includes multiple select gates (e.g., a source select gate and a drain select gate). Some of the structures described in this paragraph are understood by those skilled in the art and are not shown in fig. 1.

The memory array structure 102 may include one or more TACs 110, each TAC110 extending vertically through at least a portion of the memory array structure 102 (e.g., memory array stack 109). In some embodiments, the TAC110 may extend vertically through the entire thickness of the memory array structure 102, i.e., between two nominally parallel surfaces of the front and back of the memory array structure 102. For example, the TACs 110 may pass through the entire thickness of the alternating conductor/dielectric stack and the entire thickness of the substrate of the memory array structure 102. In some embodiments, the TAC110 may extend vertically to a partial thickness of the alternating conductor/dielectric stack and a partial thickness of the substrate of the memory array structure 102. In one illustration, the TAC110 may traverse the entire thickness of the alternating conductor/dielectric stack and a portion of the thickness of the substrate of the memory array structure 102. In another illustration, the TACs 110 may pass through a portion of the thickness of the alternating conductor/dielectric stack without reaching the substrate. Each TAC110 may include a vertical opening filled with a conductor material including, but not limited to, tungsten (W), cobalt (Co), copper (Cu), aluminum (Al), doped silicon, silicide, or any combination thereof.

Memory array structure 102 may further include one or more memory array contacts 112. The memory array contacts 112 may be located within the memory array region and/or outside the memory array region, such as within a stair-step region of the memory array structure 102. The memory array contacts 112 may include word line contacts, bit line contacts, and gate select contacts. Word line contacts may be in the stepped region and electrically connected to the word lines such that each word line contact can individually address a corresponding word line. The bit line contacts may be electrically connected to the NAND strings by bit lines such that each bit line contact can individually address a corresponding NAND string. The gate select contact may be electrically connected to the select gate. The memory array contacts 112 may comprise a conductive material including, but not limited to, W, Co, Cu, Al, silicide, or any combination thereof. Some of the structures described in this paragraph are understood by those skilled in the art and are not shown in fig. 1.

As shown in fig. 1, interconnect layer 106 may include a first dielectric layer 114 on a front side of memory array structure 102, a metal layer 118 on a front side of peripheral device structure 104, and a second dielectric layer 122 on metal layer 118. As described further below, the interconnect layer 106 may include a plurality of first contacts 116 in the first dielectric layer 114, a plurality of second contacts 124 in the second dielectric layer 122, and a plurality of metal patterns 120 in the metal layer 118. In some embodiments, the interconnect layer 106 further includes a bonding interface 129 between the first dielectric layer 114 and the second dielectric layer 122. For example, the first dielectric layer 114 and the second dielectric layer 122 may be connected face to face by hybrid bonding. Hybrid bonding (also referred to as "metal/dielectric hybrid bonding") can be a direct bonding technique (e.g., forming a bond between surfaces without the use of an intermediate layer, such as solder or an adhesive), which results in both metal-to-metal and dielectric-to-dielectric bonding effects. By hybrid bonding, chemical bonds may be formed between the dielectric material of the first dielectric layer 114 and the dielectric material of the second dielectric layer 122, and physical interdiffusion may occur between the conductor material (e.g., Cu) of the first contact 116 and the conductor material (e.g., Cu) of the second contact 124.

The dielectric material of the first dielectric layer 114 and the second dielectric layer 122 may include, but is not limited to, silicon oxide, silicon nitride, silicon oxynitride, low-k dielectric, or any combination thereof. The first contact 116 and the second contact 124 may each comprise a vertical opening (e.g., a via or trench) filled with a conductor material including, but not limited to, W, Co, Cu, Al, silicide, or any combination thereof. The term "contact," as used herein, may broadly encompass any suitable type of interconnect, such as middle-of-line (MEOL) interconnects and back-of-line (BEOL) interconnects, including vertical interconnect vias (e.g., vias) and lateral lines (e.g., interconnect lines).

In some embodiments, the metal pattern 120 in the metal layer 118 is patterned based on the layout of the TAC110 and/or the first and second contacts 116, 124 so that appropriate interconnect structures may be formed in the interconnect layer 106 to provide electrical connections for testing structures in the 3D memory device 100. The metal pattern 120 may include, but is not limited to, W, Co, Cu, Al, metal silicide, or any combination thereof. A dielectric material, such as silicon oxide, silicon nitride, silicon oxynitride, low-k dielectric, or any combination thereof, may be formed in metal layer 118 to electrically isolate metal pattern 120. It is understood that the number of metal layers in interconnect layer 106 is not limited to the example shown in fig. 1, but may be any suitable number to form suitable electrical connections between memory array structure 102 and peripheral device structure 104.

In some embodiments, the interconnect structure in the interconnect layer 106 includes a first contact 116 and a second contact 124 on both sides of the bonding interface 129. In other words, the interconnect structure may pass through the bonding interface 129, which includes the electrically connected one or more first contacts 116, second contacts 124, and metal patterns 120 in the metal layer 118.

In some embodiments, the conductive pads 108 are located in or on one or more BEOL interconnect layers (not shown) at the back side of the memory array structure 102. The conductive pads 108 may be electrically connected to the TAC110 through interconnects in the BEOL interconnect layer. In some embodiments, to reduce stress induced by the conductive pads 108, the distance between the conductive pads 108 and the memory array stack 109 in the vertical direction is at least about 3 μm, such as at least 3 μm. For example, the combined thickness of the substrate of the memory array structure 102 and the BEOL interconnect layers under the conductive pads 108 may be at least 3 μm. In some embodiments, the vertical distance between the conductive pad 108 and the memory array stack 109 is between 3 μm and 10 μm (e.g., 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, within any range of the lower limit defined by any of the above values or within any range defined by any two of the above values). The conductive pad 108 may comprise a conductor material including, but not limited to, W, Co, Cu, Al, silicide, or any combination thereof.

A plurality of electrical connections may be formed in the 3D memory device 100 for testing structures in the 3D memory device 100 (hereinafter referred to as "test structures"). In some embodiments, the at least one conductive pad 108, the at least one TAC110, the at least one first contact 116, the at least one second contact 124, the at least one metal pattern 120 in the metal layer 118, and the at least one memory array contact 112 (e.g., bit line contact and/or word line contact) are electrically connected together to form an electrical connection (hereinafter also referred to as a "signal path") for testing the test structure.

It should be appreciated that it may not be necessary to test all of the repeating structures in memory array structure 102 (e.g., an array of NAND strings, each having multiple memory cells, multiple memory fingers, blocks, and planes, or multiple bit lines and word lines). In some embodiments, one or more sample structures of the repeating structure may be tested to substantially reflect the characteristics of the repeating structure. Thus, in some embodiments, only portions of the conductive pads 108, TACs 110, memory array contacts 112, and interconnect structures in the interconnect layer 106 are used to form electrical connections for testing the sample test structure.

In some embodiments, peripheral structure 104 includes a peripheral (not shown) on a substrate. The peripheral devices may include any suitable digital, analog, and/or mixed-signal peripheral circuitry for facilitating operation of the 3D memory device 100. For example, the peripheral devices may include one or more page buffers, decoders (e.g., row and column decoders), drivers, charge pumps, current or voltage references, or any active or passive component in a circuit (e.g., a transistor, diode, resistor, or capacitor). In some embodiments, the peripheral is formed in CMOS technology, and the peripheral structure 104 may be referred to as a "CMOS structure" or "CMOS chip.

As shown in fig. 1, peripheral structure 104 may include one or more test circuits 126 on the front side of peripheral structure 104 that are electrically connected to metal pattern 120 of metal layer 118. In some embodiments, the test circuitry 126 is electrically connected to the conductive pads 108, the TACs 110, the memory array contacts 112, and the interconnect structures in the interconnect layer 106. That is, the test circuit 126 may be part of an electrical connection of a test structure for testing the 3D memory device 100. The test circuitry 126 may include one or more peripherals and/or dedicated test components for testing. In some embodiments, the test circuitry 126 includes memory array structure test circuitry for testing test structures in the memory array structure 102 and contact signal path test circuitry for testing interconnect structures in the interconnect layer 106. The memory array structure test circuit may include a memory plane test circuit, a memory block test circuit, a bit line test circuit, and a word line test circuit. In some embodiments, test circuitry 126 includes peripheral structure test circuitry, such as page buffers, decoders, etc., for testing structures in peripheral structure 104.

FIG. 1 additionally shows an exemplary probe card 130 for testing the 3D memory device 100. The probe card 130 may be an interface between an electronic test system (not shown), such as a controller, and a "component under test" (DUT), such as the 3D memory device 100. The probe card 130 may include a Printed Circuit Board (PCB)132 having an opening (not shown) into which the 3D memory device 100 may be inserted and docked for testing. The probe card 130 may further include a plurality of terminal pins 134 configured to provide electrical connection between the electronic test system and the PCB 132. The probe card 130 may further include a plurality of probes 136, the probes 136 being in contact with the conductive pads 108 when the 3D memory device 100 is docked in the probe card 130 during testing. In some embodiments, the number of probes 136 is the same as the number of conductive pads 108. In some embodiments, the layout of the conductive pads 108 matches the arrangement of the probes 136 of the probe card 130 so that each conductive pad 108 can be brought into contact with a corresponding probe 136 during testing. In some embodiments, the probe card 130 further includes a moving structure (not shown) configured to move the probe card 130 in a vertical direction and/or a lateral direction to align the probes 136 with the conductive pads 108.

In some embodiments, when the 3D memory device 100 is docked to the probe card 130, an input test signal (e.g., a voltage signal or a current signal) is provided by the electronic test system to the probe card 130 to test the test structures of the 3D memory device 100. An input signal may be received by the 3D memory device 100 at the first conductive pad 108 through the first probe 136. The input signal may then be transmitted to the test structure through the first electrical connection, as described in detail above. An output signal (e.g., another voltage signal or another current signal) may be received from the test structure at the second conductive pad 108 through the second electrical connection, as described in detail above. The probe card 130 may then transmit the output signal to an electronic test system through the second probes 136 that are in contact with the second conductive pads 108. Based on the input signals, the output signals, and the test structure, the electronic test system may determine one or more characteristics (e.g., resistance or capacitance) of the test structure and/or the quality of the hybrid bond.

Fig. 2 is a top view of an exemplary 3D memory device 200 shown in accordance with some embodiments of the present disclosure. In some embodiments, the 3D memory device 200 is the same as the 3D memory device 100 depicted in fig. 1. The 3D memory device 200 may include a face-to-face hybrid bonded peripheral structure 202 (e.g., a CMOS chip) and a memory array structure 204 (e.g., including the four memory faces shown in fig. 2).

As shown in fig. 2, the 3D memory device 200 may include a plurality of conductive pads 206 on a top surface of the 3D memory device 200, for example, on a back surface of the memory array structure 204. Each conductive pad 206 may overlap with the memory array structure 204. In the example of fig. 2, each conductive pad 206 may completely overlap the memory array structure 204, i.e., within the boundaries of the memory array structure 204 in a top view. It is to be understood that in some embodiments, the one or more conductive pads 206 partially overlap the memory array structure 204, i.e., partially outside the boundaries of the memory array structure 204. Nonetheless, by overlapping the conductive pads 206 and the memory array structure 204, the die size of the 3D memory device 200 may be reduced. In some embodiments, the conductive pads 206 are nominally identical in top view, e.g., have nominally identical dimensions and nominally identical shapes in top view. In some embodiments, the spacing of adjacent conductive pads 206 is also nominally the same. The layout of the conductive pads 206 in the top view may be designed to match the configuration of probes of a probe card used to test the 3D memory device 200.

In some embodiments, the 3D memory device 200 also includes various memory array contacts, including word line contacts 208 and bit line contacts 210. In some embodiments, to ensure uniform bonding and reduce dishing at the bonding interface, dummy contacts 212 may be added to the memory array structure 204. The dummy contacts in both the memory array structure 204 and the peripheral structure 202 may be physically joined but not electrically connected. It will be appreciated that due to the flip-chip bonding of the memory array structure 204, the memory array contacts and dummy contacts cannot be seen in a top view and are therefore represented in dashed lines in fig. 2.

Fig. 3 and 4 are schematic diagrams illustrating exemplary test structures for a set of contact signal paths according to some embodiments of the present disclosure. In addition to structures in the memory array structure and the peripheral device structure, the test structure may also include an interconnect structure in an interconnect layer between the memory array structure and the peripheral device structure. The characteristics of the interconnect structure (e.g., resistance and/or capacitance) may reflect the quality of the hybrid bond performed to form the 3D memory device (e.g., 3D memory devices 100 and 200). In some embodiments, the interconnect structure in the interconnect layer may include a first contact (e.g., first contact 116 in fig. 1) for the memory array structure and a second contact (e.g., second contact 124 in fig. 1) for the peripheral device structure, the first and second contacts contacting each other through a bonding interface. Hereinafter, the electrical connection formed by the at least one first contact and the at least one second contact is referred to as a "contact signal path". The characteristics of the contact signal path (e.g., resistance and/or capacitance) may reflect the quality of the hybrid bond, such as the accuracy of contact alignment and the presence of gaps at the mating surfaces.

The configuration of the interconnect structure may be different when testing different characteristics (e.g., resistance or capacitance) of the contact signal path. Also, because the capacitance or resistance of one contact signal path may be relatively small at times, measuring the capacitance or resistance of only one contact signal path may result in large deviations, resulting in inaccurate test results.

Accordingly, in some embodiments, the present disclosure provides a method for improving the accuracy of a test contact signal path. The method includes providing an interconnect structure to test a plurality of contact signal paths, obtaining test values for the plurality of contact signal paths, and averaging the test values for the plurality of contact signal paths. The average value may be considered a test result of a touch signal path. For example, when a set of contact signal paths includes n contact signal paths and the resistance of the entire set of contact signal paths is R, the resistance of a contact signal path is thus R/n, where n is a positive integer.

The configuration of the interconnect structure may be different when testing the resistance or capacitance of the contact signal path. In some embodiments, to test the resistance of the contact signal path, the first contact and the second contact forming the contact signal path are connected in series. In other words, the interconnect structure contacting the signal path may have a serpentine structure, for example, as shown in fig. 3. Fig. 3 illustrates four contact signal paths 302, 304, 306, and 308 connected in series. The connections between the contact signal paths may be formed by metal patterns in metal layers above and/or below the contacts (labeled as thick solid lines in fig. 3), such as metal pattern 120 in metal layer 118 in fig. 1. It should be understood that although not shown in FIG. 3, as shown in FIG. 1, the set of contact signal paths 302, 304, 306, and 308 may be electrically connected in series to conductive pads, TACs, metal patterns, and memory array contacts to form complete electrical connections for testing. In some embodiments, when measuring the resistance of a set of contact signal paths 302, 304, 306, and 308, two probes of a probe card may contact two conductive pads (labeled as arrows in fig. 3) corresponding to contact signal paths 302 and contact signal paths 308, respectively.

In some embodiments, a method for testing capacitance of a touch signal path is provided. The interconnect structure of the contact signal paths may have a comb-like structure (e.g., as shown in fig. 4) such that the contact signal paths of each half are connected in parallel. For example, odd-numbered contact signal paths may be connected in parallel, while even-numbered contact signal paths are connected in parallel. The contact signal paths are sequentially numbered from one end of the interconnect structure to the other end of the interconnect structure according to the location of each contact signal path in the interconnect structure. Specifically, assuming that the interconnect structure includes n contact signal paths, the n contact signal paths are sequentially numbered as a first contact signal path, a second contact signal path, and up to an nth contact signal path.

Fig. 4 shows four contact signal paths 402, 404, 406, and 408 in a comb configuration. The first contact signal path 402 and the third contact signal path 406 may be connected in parallel, and the second contact signal path 404 and the fourth contact signal path 408 may be connected in parallel. The connections between contact signal paths 402 and 406 and the connections between contact signal paths 404 and 408 may be made up of metal patterns (labeled as thick solid lines in fig. 4) in metal layers above and/or below the contacts, such as metal pattern 120 in metal layer 118 in fig. 1. When measuring the capacitance of a set of contact signal paths 402, 404, 406, and 408, two probes of the probe card can contact two conductive pads (labeled arrows in FIG. 4) corresponding to contact signal path 402 and contact signal path 408, respectively.

Fig. 5 is a flow chart illustrating an example method 500 for forming a 3D memory device in accordance with some embodiments of the present disclosure. Figures 7A-7J illustrate exemplary fabrication methods for forming a 3D memory device, in accordance with some embodiments of the present disclosure. Examples of the 3D memory devices of fig. 5 and 7A-7J are the 3D memory devices 100 and 200 depicted in fig. 1 and 2. It should be understood that the steps shown in method 500 are not comprehensive, and that other steps may be performed before, after, or between any of the shown steps.

As shown in fig. 5, the method 500 begins at step 502, where a memory array structure is formed. As shown in fig. 7A, memory array stack 109 can be formed on the front side of substrate 702. Memory array contacts 112 (e.g., word line contacts, bit line contacts, and select gate contacts) may be formed on the front side of the memory array structure 102. For ease of illustration, memory array structure 102 is shown inverted in fig. 7A-7J such that the back side of memory array structure 102 is above the front side. However, it should be understood that during fabrication, memory array structure 102 may be flipped such that the backside of substrate 702 becomes the bottom side of memory array structure 102 during fabrication. In some embodiments, the memory array stack 109 is formed by a number of manufacturing processes including, but not limited to, thin film deposition of dielectric layers, etching of via holes and slits, thin film deposition of memory films in the via holes to replace the gates and word lines. With respect to memory array contacts 112, a dry/wet etch process may be used to pattern and etch vertical openings through the dielectric layer, followed by deposition of a conductive material and Chemical Mechanical Polishing (CMP) of the excess conductive material.

The method 500 continues to step 504, as shown in fig. 5, where one or more TACs are formed, each extending vertically through the memory array stack. As shown in fig. 7B, the TACs 110 are formed in the memory array structure 102, wherein each TAC110 extends vertically through the entire thickness of the memory array stack 109. In some embodiments, the fabrication method of forming the TAC110 includes forming vertical openings through the memory array stack 109 using a dry/wet etch process, followed by filling the openings with conductor material and other materials for isolation purposes, such as dielectric materials. The TACs 110 may include a conductive material including, but not limited to, W, Co, Cu, Al, silicide, or any combination thereof. The openings of the TAC110 may be filled using Atomic Layer Deposition (ALD), Chemical Vapor Deposition (CVD), Physical Vapor Deposition (PVD), electroplating, any other suitable method, or any combination thereof.

The method 500 continues with step 506 in which a first dielectric layer is formed on the front side of the memory array structure, as shown in fig. 5. As shown in fig. 7C, a first dielectric layer 114 is formed on the front surface of the memory array structure 102. The first dielectric layer 114 may be formed using one or more thin film deposition methods, such as ALD, CVD, PVD, or any combination thereof. The first dielectric layer 114 may include a dielectric material including, but not limited to, silicon oxide, silicon nitride, low-k dielectric, or any combination thereof.

The method 500 continues with step 508, as shown in fig. 5, in which a plurality of first contacts are formed in the first dielectric layer. As shown in fig. 7D, a first contact 116 is formed in the first dielectric layer 114. At least some of the first contacts 116 may be in contact with the TAC110 to form an electrical connection with the TAC 110. At least some of the first contacts 116 may be in contact with the memory array contacts 112, forming electrical connections with the memory array contacts 112. In some embodiments, the fabrication method of forming the first contact 116 includes forming a vertical opening through the first dielectric layer 114 using a dry/wet etch process, followed by filling the opening with a conductive material. The first contact 116 may comprise a conductive material including, but not limited to, W, Co, Cu, Al, silicide, or any combination thereof. The opening of the first contact 116 may be filled using ALD, CVD, PVD, electroplating, any other suitable method, or any combination thereof.

The method 500 continues to step 510, as shown in fig. 5, where through silicon contacts (e.g., Through Silicon Vias (TSVs)) are formed from the backside of the memory array structure. As shown in fig. 7E, a Through Silicon Via (TSV)704 may be formed through the substrate 702 from the backside of the memory array structure 102 (e.g., the backside of the substrate 702). Each TSV704 may contact a corresponding TAC110 to form an electrical connection between the TSV704 and the TAC 110. In some embodiments, substrate 702 is thinned from its backside prior to forming TSV704 using, for example, grinding, wet etching, dry etching, CMP, or any combination thereof. TSV704 may be formed by a substrate having a full thickness or a thinned substrate. In some embodiments, the fabrication method of forming the TSV includes forming a vertical opening through the substrate 702 (whether or not the substrate 702 has been thinned) using a dry/wet etch process, followed by filling the opening with a conductive material. TSVs 704 may include conductive materials as well as other materials (e.g., dielectric materials) used for isolation purposes. The conductor material may include, but is not limited to, W, Co, Cu, Al, silicide, or any combination thereof. The opening of the TSV704 may be filled using ALD, CVD, PVD, electroplating, any other suitable method, or any combination thereof.

In some embodiments, the TAC110 extends vertically through a portion of the entire thickness of the memory array stack 109. That is, the TAC110 may not reach the substrate 702, and the TSV704 may further extend vertically into the memory array stack 109 to contact the TAC110 in the memory array stack 109. In some embodiments, the TAC110 extends vertically not only through the entire thickness of the memory array stack 109, but also into the substrate 702. Thus, the TSV704 may contact the TAC110 in the substrate 702. In some embodiments, the TAC110 extends vertically through the entire thickness of the memory array stack 109 and the entire thickness of the substrate 702. Accordingly, the TSV704 may be omitted.

The method 500 continues to step 512, as shown in FIG. 5, where a plurality of conductive pads are formed on the back side of the memory array structure. As shown in fig. 7F, a conductive liner 128 may be formed over the backside of the memory array structure 102 and the TSV 704. The conductive pad 128 may be electrically connected to the TSV704, the TAC110, the first contact 116, and the memory array contact 112. In some embodiments, one or more BEOL interconnect layers are formed on the backside of the substrate 702 and the conductive pads 128 are formed on the BEOL interconnect layers. In some embodiments, the conductive pad 128 is part of a BOEL interconnect layer. In some embodiments, the fabrication method of forming the conductive pad 128 includes forming one or more dielectric layers and forming a vertical opening through the dielectric layers using a dry/wet etch process, followed by filling the opening with a conductive material. The conductive liner 128 may comprise a conductor material including, but not limited to, W, Co, Cu, Al, silicide, or any combination thereof. The openings of the conductive liner 128 may be filled using ALD, CVD, PVD, electroplating, any other suitable method, or any combination thereof.

The method 500 continues to step 514 as shown in fig. 5, where a peripheral structure (e.g., CMOS structure) is formed. It should be understood that the order of performing steps 502-512 and 514-520 is not limited. In some embodiments, steps 502-512 and 514-520 may be performed in parallel. As shown in fig. 7A, test circuitry 126 is formed on the front side of peripheral structure 104. The test circuit 126 may include transistors and local interconnects of transistors formed by standard CMOS processes. One or more peripherals (not shown) may also be formed in the peripheral structure 104 by standard CMOS processes.

The method 500 continues to step 516, as shown in FIG. 5, where a metal layer is formed on the front side of the peripheral device structure. As shown in fig. 7G, a metal layer 118 including a metal pattern 120 is formed on the front surface of the peripheral device structure 104. In some embodiments, metal pattern 120 may be in contact with test circuitry 126 and/or peripheral devices in peripheral device structure 104. In some embodiments, the metal layer 118 is formed by a method including forming a dielectric layer and patterning openings (e.g., vias and trenches) of the metal pattern 120 in the dielectric layer by photolithography. The openings may be filled with a conductive material including, but not limited to, W, Co, Cu, Al, silicide, or any combination thereof using ALD, CVD, PVD, electroplating, any other suitable method, or any combination thereof.

The method 500 continues with step 518 in which a second dielectric layer is formed over the metal layer, as shown in fig. 5. As shown in fig. 7H, a second dielectric layer 122 is formed on the metal layer 118. The second dielectric layer 122 may be formed using one or more thin film deposition methods, such as ALD, CVD, PVD, or any combination thereof. The second dielectric layer 122 may comprise a dielectric material including, but not limited to, silicon oxide, silicon nitride, low-k dielectric, or any combination thereof.

The method 500 continues with step 520 in which a plurality of second contacts are formed in the second dielectric layer, as shown in fig. 5. As shown in fig. 7I, a second contact 124 is formed in the second dielectric layer 122. At least some of the second contacts 124 may be in contact with the metal pattern 120 to form electrical connections with the metal pattern 120 and the test circuit 126. In some embodiments, forming the second contact fabrication method includes forming a vertical opening through the second dielectric layer 122 using a dry/wet etch process, followed by filling the opening with a conductive material. The second contact 124 may include a conductive material including, but not limited to, W, Co, Cu, Al, silicide, or any combination thereof. The opening of the second contact 124 may be filled using ALD, CVD, PVD, electroplating, any other suitable method, or any combination thereof.

The method 500 continues with step 522 in which the first dielectric layer and the second dielectric layer are connected face-to-face such that the memory array structure is above the peripheral device structure, as shown in fig. 5. The bonding of the first and second dielectric layers may be performed by hybrid bonding. The first contact may contact the second contact at the engagement interface. As shown in fig. 7J, the memory array structure 102 may be flipped such that the first dielectric layer 114 and the second dielectric layer 122 are disposed face to face. After hybrid bonding, memory array structure 102 is over peripheral structure 104. As such, the first contact 116 and the second contact 124 may contact each other at the bonding interface 129. At least portions of the conductive pad 128, the TSV704, the TAC110, the memory array contact 112, the first contact 116, the second contact 124, the metal pattern 120, and the test circuit 126 may form an electrical connection for testing a test structure of the 3D memory device.

FIG. 6 is a flow chart illustrating an example method 600 for testing a 3D memory device in accordance with some embodiments of the present disclosure. Examples of the 3D memory device of fig. 6 are the 3D memory devices 100 and 200 depicted in fig. 1 and 2. It should be understood that the steps shown in method 600 are not comprehensive, and that other steps may be performed before, after, or between any of the shown steps.

As shown in FIG. 6, method 600 begins at step 602, where an input test signal for testing a test structure in a 3D memory device is received. In some embodiments, the test structure includes any structure of the memory array structure that is electrically connected to at least one memory array contact (e.g., a word line contact, a bit line contact, or a select gate contact). For example, a test structure may include one or more NAND strings, one or more memory fingers, one or more memory blocks, one or more memory planes, one or more bit lines, one or more word lines, and one or more gate select lines. In some embodiments, the test structure includes any interconnect structure in an interconnect layer in which a bonding interface is formed. The test structure may include one or more contact signal paths, each contact signal path including a first contact for the memory array structure and a second contact for the peripheral device structure. In some embodiments, the test structure includes any peripheral in the peripheral structure that is electrically connected to a portion of the test circuitry in the peripheral structure.

The input test signals may be generated by an electronic test system connected to the probe card in accordance with the test structure and/or the characteristics to be tested. The input test signal may be a dc voltage signal, an ac voltage signal, or a current signal. An input test signal may be applied to a first conductive pad of the 3D memory device through a corresponding probe in contact with the first conductive pad. The first conductive pad may be determined according to a test structure. At least a portion of the first conductive pad may be located on a top surface of the 3D memory device.

The method 600 continues to step 604, as shown in FIG. 6, where an input test signal is transmitted to the test structure through the first conductive pad and the first electrical connection. The first electrical connection may include the first TAC (and in some embodiments, the first TSV) and a first interconnect structure (e.g., including one or more first contacts for a memory array structure, one or more second contacts for a peripheral device structure, and one or more metal patterns). In some embodiments, the first electrical connection may also include a memory array contact (e.g., a bit line contact or a word line contact) and/or a test circuit.

The method 600 continues to step 606, as shown in FIG. 6, where the output test signal from the test structure is received by another probe of the probe card through the second electrically conductive pad and the second electrical connection. The second electrical connection may include the second TAC (and in some embodiments, the second TSV) and a second interconnect structure (e.g., including one or more first contacts for a memory array structure, one or more second contacts for a peripheral device structure, and one or more metal patterns). In some embodiments, the second electrical connection may also include a memory array contact (e.g., a bit line contact or a word line contact) and/or test circuitry.

The output test signal may be a dc voltage signal, an ac voltage signal, or a current signal. The output test signal may be transmitted to a second conductive pad of the 3D memory device and acquired by a corresponding probe contacting the second conductive pad. The second conductive pad may be determined according to the test structure. At least a portion of the second conductive pad may be on a top surface of the 3D memory device.

Method 600 continues at step 608, as shown in FIG. 6, where characteristics of the test structure are determined based on the input test signal, the output test signal, and the test structure. The characteristic may comprise a resistance or capacitance of the test structure, and its value may be calculated by the electronic test system.

In some embodiments, various characteristics of the same test structure and/or the same characteristics of various test structures may be tested simultaneously to improve testing efficiency. Once the 3D memory device is docked into the probe card, multiple probes may contact multiple conductive pads of the 3D memory device to perform parallel testing simultaneously.

Further, because the memory array structure may include a repeating structure (e.g., an array of NAND strings, each NAND string having a plurality of memory cells, a plurality of memory fingers, blocks, and planes, or a plurality of bit lines and word lines). By designing the metal pattern layout in the metal layer, one or more sample structures of the repeating structure may be tested in parallel by the probe card. For example, the probe card may be used to test different memory blocks, different bit lines and/or word lines in the same memory block, and bit lines corresponding to word lines in different locations.

Various embodiments according to the present disclosure provide 3D memory devices having structures for testing 3D memory devices. The 3D memory devices disclosed herein may include an interconnect layer having an interconnect structure between and contacting TACs of stacked peripheral device structures (e.g., CMOS chips) and memory array structures (e.g., memory array chips). The 3D memory devices disclosed herein may further include conductive pads on the backside of the memory array structure for the probe card so that various characteristics of the different structures of the 3D memory device, as well as the quality of the hybrid bonding process to form the 3D memory, can be tested with probe cards having a true component density. Accordingly, the 3D memory device disclosed herein may enable testability and consistency of characteristics of the 3D memory device formed by hybrid bonding of the peripheral device structure and the memory array structure, thereby reducing overall process development time and improving manufacturing yield.

In some embodiments, a memory device includes a memory array structure, a first dielectric layer on a front side of the memory array structure, a plurality of first contacts in the first dielectric layer, a plurality of conductive pad structures on a back side of the memory array, a CMOS structure, a metal layer comprising a plurality of metal patterns on the front side of the CMOS structure, a second dielectric layer on the metal layer, and a plurality of second contacts in the second dielectric layer. The memory array structure includes a memory array stack, a TAC extending vertically through at least a portion of the memory array stack, and one or more memory array contacts. The first and second dielectric layers are connected face-to-face such that the memory array structure is above the CMOS structure and one or more electrical connections are formed by at least the plurality of conductive pads, the TAC, the plurality of first contacts, the plurality of second contacts, the plurality of metal patterns in the metal layer, and the one or more memory array contacts.

In some embodiments, a 3D memory device includes a memory array structure, a peripheral device structure, and an interconnect layer in contact with a front side of the memory array structure and a front side of the peripheral device structure, and a conductive pad located at a back side of the memory array structure and overlapping the memory array structure. The memory array structure includes a memory array stack, a TAC extending vertically through at least a portion of the memory array stack, and a memory array contact. The peripheral device structure includes a test circuit. The interconnect layer includes an interconnect structure. At least one of the conductive pads, the TACs, the interconnect structures, and the test circuitry and the memory array contacts are electrically connected together.

In some embodiments, a method of forming a memory device is disclosed. A memory array structure including a memory array stack and one or more memory array contacts is first formed. TACs are then formed that extend vertically through the memory array stack of at least a portion of the memory array structure. A first dielectric layer is formed on a front surface of the memory array structure. A plurality of first contacts are formed in the first dielectric layer. A plurality of conductive pads are formed on the back side of the memory array structure. A CMOS structure is formed. A metal layer including a plurality of metal patterns is formed on a front surface of the CMOS structure. And forming a second dielectric layer on the metal layer. A plurality of second contacts is formed in the second dielectric layer. The first and second dielectric layers are connected face-to-face such that the memory array structure is above the CMOS structure and one or more electrical connections are formed by at least the plurality of conductive pads, the TAC, the plurality of first contacts, the plurality of second contacts, the plurality of metal patterns in the metal layer, and the one or more memory array contacts.

In some embodiments, a method for testing a memory device is disclosed. The memory device includes a memory array structure, a first dielectric layer on a front side of the memory array structure, a plurality of first contacts in the first dielectric layer, a plurality of conductive pads on a back side of the memory array structure, a CMOS structure, a metal layer including a plurality of metal patterns on the front side of the CMOS structure, a second dielectric layer on the metal layer, and a plurality of second contacts in the second dielectric layer. The memory array structure includes a memory array stack, a TAC extending vertically through at least a portion of the memory array stack, and one or more memory array contacts. An input signal is received for testing a test structure in a memory device. An input signal is transmitted to the test structure through the first probe and a first electrical connection including one of the plurality of conductive pads, one of the plurality of TACs, one of the plurality of first contacts, one of the plurality of second contacts, one of the plurality of metal patterns in the metal layer, and at least one memory array contact of the one or more memory array contacts. An output signal is received from the test structure through the second probe and a second electrical connection including one of the plurality of conductive pads, one of the plurality of TACs, one of the plurality of first contacts, one of the plurality of second contacts, one of the plurality of metal patterns in the metal layer, and at least one memory array contact of the one or more memory array contacts. Characteristics of a test structure in a memory device are determined based on an input signal, an output signal, and the test structure.

In some embodiments, a method for testing a 3D memory device is disclosed. An input signal is applied to first conductive pads of a memory device through first probes of a probe card. At least a portion of the first conductive pad is located on a top surface of the memory device. An input signal is transmitted to a test structure of the memory device through at least one of the first conductive pad, the first TAC of the memory device, the first interconnect structure passing through a bonding interface of the memory device, and a memory array contact and test circuit of the memory device. The output signal is received from the test structure through at least one second interconnect structure passing through the bonding interface, a second TAC of the memory device, and at least one of a memory array contact and a test circuit. The output signal is received from a second conductive pad of the memory device through a second probe of the probe card. At least a portion of the second conductive pad is located on the top surface of the memory device. The characteristics of the test structure are determined from the input signal and the output signal.

The foregoing description of the specific embodiments will so fully reveal the general nature of the disclosure that others can, by applying knowledge within the skill of the relevant art, readily modify and/or adapt for various applications such specific embodiments without undue experimentation and without departing from the general concept of the present disclosure. Accordingly, such modifications and adaptations are intended to be within the meaning and range of equivalents of the disclosed embodiments, based on the teaching and guidance presented herein. It is to be understood that the phraseology or terminology herein is for the purpose of description and not of limitation, such that the terminology or phraseology of the present specification is to be interpreted by the skilled artisan in light of the teachings and guidance.

Embodiments of the disclosure have been described with the aid of functional building blocks illustrating the implementation of specific functions and relationships thereof. For convenience of description, boundaries/boundaries of these functional building blocks have been arbitrarily defined herein, and alternate boundaries/boundaries may be defined when appropriate to achieve the specified functions and relationships.