阅读说明：本技术 具有垂直扩散板的电容器结构 (Capacitor structure with vertical diffusion plate ) 是由 陈亮 于 2019-01-30 设计创作，主要内容包括：一种电容器结构,包括半导体衬底、设置在半导体衬底中的第一垂直扩散板、设置在半导体衬底中并围绕第一垂直扩散板的第一浅沟槽隔离(STI)结构、以及设置在半导体衬底中并围绕第一STI结构的第二垂直扩散板。第一垂直扩散板还包括作为半导体衬底的一部分的第一下部。第一下部被第一晶片背面沟槽隔离结构围绕并电隔离。第一晶片背面沟槽隔离结构与第一STI结构的底部直接接触。(A capacitor structure includes a semiconductor substrate, a first vertical diffuser plate disposed in the semiconductor substrate, a first Shallow Trench Isolation (STI) structure disposed in the semiconductor substrate and surrounding the first vertical diffuser plate, and a second vertical diffuser plate disposed in the semiconductor substrate and surrounding the first STI structure. The first vertical diffusion plate further includes a first lower portion as a part of the semiconductor substrate. The first lower portion is surrounded and electrically isolated by a first wafer backside trench isolation structure. The first wafer backside trench isolation structure is in direct contact with a bottom of the first STI structure.)

1. A method for fabricating a capacitor structure comprising

Forming alternating concentric rings of vertical diffuser plates and concentric rings of STI structures alternately interposed between the concentric rings of vertical diffuser plates on a front surface of a semiconductor substrate;

turning over the semiconductor substrate, and thinning the back surface of the semiconductor substrate to remove a part of the semiconductor substrate from the back surface;

forming a plurality of wafer backside trench isolation structures on the backside of the semiconductor substrate.

2. The method of claim 1, forming the STI structure comprising:

etching a ring-shaped isolation trench into the semiconductor substrate;

forming a liner layer on an inner surface of the annular isolation trench;

filling the annular isolation trench with a trench filling insulation layer;

and carrying out chemical mechanical polishing to remove the redundant groove filling insulating layer outside the annular isolation groove.

3. The method of claim 2, wherein the liner layer comprises silicon oxide or silicon nitride.

4. The method of claim 2 wherein the trench fill insulating layer is silicon dioxide or HDPCVD oxide.

5. The method of claim 1, wherein the vertical diffuser plate is formed by a multiple ion implantation process.

6. The method of claim 1, wherein the plurality of wafer backside trench isolation structures are formed in direct contact with a bottom of the respective STI structure.

7. The method of claim 6, wherein each of the wafer backside trench isolation structures has a lateral thickness that is less than a lateral thickness of the STI structure in contact therewith.

8. The method of claim 1, wherein the wafer backside trench isolation structure is formed to have a ring shape that is the same as a ring shape of the STI structure.

9. The method of claim 1, wherein the vertical diffuser plate is a P-type doped or N-type doped region.

10. The method of claim 1, further comprising providing an insulating layer on a backside of the semiconductor substrate.

11. The method of claim 1, further comprising forming heavily doped regions on a surface of the respective vertical diffuser plate.

12. The method of claim 1, wherein the vertical diffuser plate is a silicon active region defined and isolated by the STI structures.

13. The method of claim 1, further comprising forming a passive element directly on a top surface of the STI structure.

14. The method of claim 13, wherein the passive element comprises a resistor.

15. The capacitor structure of claim 13, wherein the passive element comprises polysilicon.

16. The method of claim 13, further comprising:

depositing a dielectric layer on the front side of the semiconductor substrate after forming the passive elements;

forming an interconnect structure on the dielectric layer;

the interconnect structures are utilized to connect respective vertical diffuser plates to the anode and cathode nodes, respectively.

17. The method of claim 16, the interconnect structure comprising contact plugs and metal lines/traces.

18. The method of claim 1, forming a plurality of the wafer backside trench isolation structures comprising: forming concentric annular trenches in the semiconductor substrate by a photolithography and etching process; and filling the concentric annular trenches with an insulating material.

19. The method of claim 1, wherein the semiconductor substrate is a silicon substrate.

Technical Field

The present disclosure relates generally to the field of semiconductor technology and, more particularly, to capacitor structures having a vertically arranged diffuser plate in a silicon substrate.

Background

As is known in the art, 3D NAND is a flash memory technology that vertically stacks memory cells to increase capacity to achieve higher storage density and lower cost per gigabyte.

In 3D NAND technology, the memory cell operates at high voltage and requires a capacitor to achieve boosting. Typically, MOS capacitors, MOM capacitors, or poly-poly capacitors are used in 3D NAND chip circuits.

As 3D NAND technology moves toward high density and high capacity, particularly from 64-layer to 128-layer schemes, the number of devices and the number of traces increase significantly while the chip area remains substantially unchanged. As a result, the space for silicon wafers and later wiring is getting smaller. Conventional MOS capacitors or MOM capacitors typically require large chip area or metal trace area at a later stage, and large area MOS capacitors may lead to time-dependent dielectric breakdown (TDDB) problems.

Thus, there remains a need in the art for a novel capacitor structure that meets circuit requirements while not requiring much space.

Disclosure of Invention

It is an object of the present disclosure to provide a capacitor structure with a vertically arranged diffuser plate in a silicon substrate that addresses the above-mentioned drawbacks and deficiencies of the prior art.

One aspect of the present disclosure provides a capacitor structure including a semiconductor substrate, a first vertical diffuser plate disposed in the semiconductor substrate, a first Shallow Trench Isolation (STI) structure disposed in the semiconductor substrate and surrounding the first vertical diffuser plate, and a second vertical diffuser plate disposed in the semiconductor substrate and surrounding the first STI structure. The first vertical diffusion plate further includes a first lower portion as a part of the semiconductor substrate. The first lower portion is surrounded and electrically isolated by a first wafer backside trench isolation structure.

According to some embodiments, the first wafer backside trench isolation structure is in direct contact with a bottom of the first STI structure.

According to some embodiments, the lateral thickness t of the first wafer backside trench isolation structure is less than the lateral thickness of the first STI structure.

According to some embodiments, the first wafer backside trench isolation structure has a ring shape that is substantially the same as the ring shape of the first STI structure.

According to some embodiments, the first vertical diffusion plate is a P-type doped or N-type doped region.

According to some embodiments, the second vertical diffusion plate is a P-type doped or N-type doped region.

According to some embodiments, the capacitor structure further comprises an insulating layer disposed on the back side of the semiconductor substrate.

According to some embodiments, the first STI structure and the first wafer backside trench isolation structure isolate the first vertical diffuser plate from the second vertical diffuser plate.

According to some embodiments, the first vertical diffuser plate is electrically coupled to a first voltage and the second vertical diffuser plate is electrically coupled to a second voltage, wherein the second voltage is higher than the first voltage.

According to some embodiments, a capacitor is formed between a first vertical diffuser plate and a second vertical diffuser plate, wherein a first STI structure and a first wafer backside trench isolation structure interposed between the first vertical diffuser plate and the second vertical diffuser plate serve as a capacitor dielectric layer.

According to some embodiments, the capacitor structure further includes a first heavily doped region disposed at a surface of the first vertical diffusion plate, and a second heavily doped region disposed at a surface of the second vertical diffusion plate.

According to some embodiments, the capacitor structure further comprises a second Shallow Trench Isolation (STI) structure disposed in the semiconductor substrate. The second STI structure surrounds the second vertical diffuser plate, the first STI structure, and the first vertical diffuser plate.

According to some embodiments, the second vertical diffusion plate further includes a second lower portion that is a part of the semiconductor substrate.

According to some embodiments, the second lower portion is surrounded and electrically isolated by the second wafer backside trench isolation structure and the first wafer backside trench isolation structure.

According to some embodiments, the second STI structure, the second vertical diffuser plate, and the first STI structure are concentrically arranged with the first vertical diffuser plate.

According to some embodiments, the first and second vertical diffuser plates are silicon active regions defined and isolated by the first and second STI structures.

According to some embodiments, the capacitor structure further comprises a passive element directly on a top surface of the first or second STI structure.

According to some embodiments, the passive element comprises a resistor. According to some embodiments, the passive component comprises polysilicon.

According to some embodiments, the capacitor structure further includes a third vertical diffuser plate surrounding the second STI structure, the second vertical diffuser plate, the first STI structure, and the first vertical diffuser plate, and a third Shallow Trench Isolation (STI) structure surrounding the third vertical diffuser plate, the second STI structure, the second vertical diffuser plate, the first STI structure, and the first vertical diffuser plate.

According to some embodiments, the capacitor structure further includes a fourth vertical diffuser plate surrounding the third STI structure, the third vertical diffuser plate, the second STI structure, the second vertical diffuser plate, the first STI structure, and the first vertical diffuser plate, and a fourth Shallow Trench Isolation (STI) structure surrounding the fourth vertical diffuser plate, the third STI structure, the third vertical diffuser plate, the second STI structure, the second vertical diffuser plate, the first STI structure, and the first vertical diffuser plate.

According to some embodiments, the second vertical diffuser plate, the fourth vertical diffuser plate, and the ion trap are electrically coupled to the anode node, and the first vertical diffuser plate and the third vertical diffuser plate are electrically coupled to the cathode node.

According to some embodiments, the semiconductor substrate is a silicon substrate.

These and other objects of the present invention will no doubt become obvious to those of ordinary skill in the art after having read the following detailed description of the preferred embodiments which are illustrated in the various drawing figures and drawings.

Drawings

The accompanying drawings, which are incorporated herein and constitute part of the specification, illustrate embodiments of the disclosure and, together with the 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 schematic diagram illustrating an exemplary layout structure of a capacitor structure fabricated in a semiconductor substrate according to one embodiment of the present invention.

Fig. 2 is a schematic sectional view taken along line I-I in fig. 1.

Fig. 3 to 5 are schematic cross-sectional views illustrating an exemplary method for manufacturing a capacitor structure according to another embodiment of the present disclosure.

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

Detailed Description

Reference will now be made in detail to exemplary embodiments of the invention, which are illustrated in the accompanying drawings, for the purpose of understanding and implementing the present disclosure and to achieve a technical effect. It is to be understood that the following description is made only by way of example and not as a limitation on the present disclosure. Various embodiments of the present disclosure and various features of the embodiments that are not mutually inconsistent can be combined and rearranged in various ways. Modifications, equivalents, or improvements to the disclosure may be understood by those skilled in the art without departing from the spirit and scope of the disclosure, and are intended to be included within the scope of the disclosure.

It is noted 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. Moreover, such phrases are not necessarily referring 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 affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

In general, terms may be understood at least in part from the context in which they are used. For example, the term "one or more" as used herein may be used to describe any feature, structure, or characteristic in the singular or may be used to describe a combination of features, structures, or characteristics in the plural, depending at least in part on the context. Similarly, terms such as "a" or "the" may be understood to convey a singular use or to convey a plural use, depending at least in part on the context.

It should be readily understood that the meaning of "on …", "above …" and "above …" in this disclosure should be read in the broadest manner such that "on …" means not only "directly on" but also including the meaning of "on" something with intervening features or layers therebetween, and "on …" or "above …" means not only "on" or "above" something, but may also include the meaning of "on" or "above" something with no intervening features or layers therebetween (i.e., directly on something).

Furthermore, spatially relative terms such as "below …," "below …," "lower," "above …," "upper," and the like may be used herein for ease of description to describe one element or feature's relationship to another element or feature or features, as illustrated in the figures.

Spatially relative terms are intended to encompass different orientations in use or operation of the device in addition to the orientation depicted in the figures. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

As used herein, the term "substrate" refers to a material to which a subsequent 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 comprise a wide range 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 that includes a region having a thickness. A layer may extend over the entirety of the underlying or overlying structure or may have an extent that is less than the extent of the underlying or overlying structure. Furthermore, a layer may be a region of a homogeneous or heterogeneous continuous structure having a thickness less than the thickness of the continuous structure. For example, a layer may be located between any horizontal pair of surfaces at the top and bottom surfaces or between the top and bottom surfaces of the continuous structure. The layers may extend horizontally, vertically and/or along inclined surfaces. The substrate may be a layer, which may include one or more layers, and/or may have one or more layers thereon, above, and/or below. The layer may comprise a plurality of layers. For example, the interconnect layer may include one or more conductors and contact layers (in which contacts, interconnect lines, and/or vias are formed) and one or more dielectric layers.

As used herein, the term "nominal" refers to a desired or targeted value of a characteristic or parameter for a component or process operation, as well as a range of values above and/or below the desired value, set during a design phase of a production or process. The range of values may be due to slight variations in manufacturing processes or tolerances. As used herein, the term "about" indicates a value of a given amount that may vary based on the particular technology node associated with the subject semiconductor device. The term "about" may indicate a given amount of a value that varies, for example, within 10% -30% of the value (e.g., ± 10%, ± 20% or ± 30% of the value), based on the particular technology node.

The present disclosure relates to capacitor structures having a vertically arranged diffuser plate in a silicon substrate. The above-described capacitor structures may be fabricated on a CMOS wafer that may be bonded to an array wafer to form a three-dimensional (3D) NAND device. Shallow Trench Isolation (STI) structures, which serve as capacitor dielectric layers, are disposed between the vertically arranged diffusion plates of the capacitor structures. At the bottom of the capacitor structure and along the periphery of the capacitor structure, wafer backside trench isolation is provided to electrically isolate diffusion plates of opposite polarity from each other. The above capacitor structure can be integrated in a polysilicon gate (polysilicon gate) capacitor/resistor region, so that the space of a CMOS wafer can be effectively used, and the capacitance per unit area can be increased.

Please refer to fig. 1 and fig. 2. Fig. 1 is a schematic diagram illustrating an exemplary layout structure of a capacitor structure fabricated in a semiconductor substrate according to one embodiment of the present invention. Fig. 2 is a schematic sectional view taken along line I-I in fig. 1. It should be understood that the shapes of the elements or layouts of the capacitor structures shown by the figures are for illustration purposes only. Different shapes or layouts may be employed according to various embodiments of the present disclosure.

As shown in fig. 1 and 2, the capacitor structure 1 may be constructed within a polysilicon gate capacitor/resistor region (P2 region) in a semiconductor substrate 100 of a semiconductor material such as silicon, but is not limited thereto. According to one embodiment of the present disclosure, the semiconductor substrate 100 may be a P-type silicon substrate, for example. However, it should be understood that other semiconductor substrates, such as silicon-on-insulator (SOI) substrates or epitaxial substrates, may be employed in accordance with other embodiments. According to one embodiment of the present disclosure, the semiconductor substrate 100 has a front surface 100a and a back surface 100 b.

On the semiconductor substrate 100, a plurality of CMOS circuit elements (not shown) may be fabricated to form a CMOS wafer. The CMOS wafer may be bonded to an array wafer (or memory cell wafer) to form a three-dimensional (3D) NAND device. The capacitor structure 1 of the present disclosure can provide a high capacitance required to achieve boosting during operation of the 3D NAND device. Furthermore, the capacitor structure 1 of the present disclosure is compatible with current CMOS processes. The capacitor structure 1 of the present disclosure is an integrated capacitor structure manufactured integrally with CMOS circuit elements.

In the non-limiting embodiment shown in fig. 1 and 2, the capacitor structure 1 includes a first vertical diffuser plate 110 surrounded by a first Shallow Trench Isolation (STI) structure 104. When viewed from above, as can be seen in fig. 1, the first vertical diffusion plate 110 may have a rectangular shape with a long axis or side extending along the reference x-axis and a short side extending along the reference y-axis. The first STI structure 104 is an annular trench isolation formed on the front surface 100a of the semiconductor substrate 100. The first STI structure 104 electrically isolates the first vertical diffuser plate 110. It is understood that different shapes or layouts of the first vertical diffuser plate 110 and the first STI structures 104 may be employed in accordance with various embodiments of the present disclosure.

According to one embodiment of the present disclosure, the first vertical diffusion plate 110 is a silicon active region defined and isolated by the first STI structures 104. According to an embodiment of the present disclosure, the first vertical diffusion plate 110 may be a P-type doped or N-type doped silicon region. For example, P-type dopants such as boron or N-type dopants such as phosphorus may be implanted into the silicon active region defined and isolated by the first STI structures 104 by performing an ion well implantation process using a suitable hard mask, which is typically performed to form an ion well in the CMOS logic circuit region, thereby forming the first vertical diffusion plate 110. Such as P⁺Region or N⁺A heavily doped region 111 of the region may be formed on a surface of the first vertical diffusion plate 110. Therefore, the doping concentration of the first vertical diffusion plate 110 after the ion trap implantation process is higher than that of the semiconductor substrate 100.

According to one embodiment of the present disclosure, for example, the first STI structure 104 may be formed by performing the following steps, including but not limited to: (1) etching a ring-shaped isolation trench into the semiconductor substrate 100; (2) forming a liner layer such as a silicon oxide or silicon nitride liner on an inner surface of the annular isolation trench; (3) filling the annular isolation trench with a trench fill insulating layer such as silicon dioxide or HDPCVD oxide; and (4) performing Chemical Mechanical Polishing (CMP) to remove the excess trench filling insulating layer outside the annular isolation trench.

According to an embodiment of the present disclosure, the first vertical diffusion plate 110 further includes a lower portion 110a as a portion of the semiconductor substrate 100. As can be seen in fig. 2, the lower portion 110a may be wider than an upper covered portion of the first vertical diffuser plate 110 surrounded by the first STI structure 104. According to one embodiment of the present disclosure, lower portion 110a is surrounded and electrically isolated by wafer backside trench isolation structure 504. According to one embodiment of the present disclosure, the wafer backside trench isolation structure 504 has a ring shape that is substantially the same as the ring shape of the first STI structure 104. According to one embodiment of the present disclosure, the wafer backside trench isolation structure 504 is in direct contact with the bottom of the first STI structure 104. According to one embodiment of the present disclosure, the lateral thickness t of the wafer backside trench isolation structure 504 is less than the lateral thickness of the first STI structure 104.

According to one embodiment of the present disclosure, an insulating layer 500 is disposed on the back surface 100b of the semiconductor substrate 100. According to one embodiment of the present disclosure, the wafer backside trench isolation structure 504 is formed by filling the wafer backside trench with an insulating layer 500. According to one embodiment of the present disclosure, the insulating layer 500 may be formed by a Chemical Vapor Deposition (CVD) method including, but not limited to, a plasma enhanced CVD (pecvd), a low pressure CVD (lpcvd), a rapid thermal CVD (rtcvd), or an Atomic Layer Deposition (ALD) method. For example, the insulating layer 500 may include silicon oxide, silicon nitride, and silicon oxynitride, but is not limited thereto.

The capacitor structure 1 further includes a second vertical diffuser plate 210 surrounding the first STI structures 104 and the first vertical diffuser plate 110. When viewed from above, as can be seen in fig. 1, the second vertical diffuser plate 210 is an annular structure surrounding the annular first STI structure 104. The second vertical diffuser plate 210 is defined and isolated by the first STI structures 104 and the outer second STI structures 105. The second STI structure 105 is also an annular trench isolation that electrically isolates the second vertical diffuser plate 210. The second STI structure 105 may be formed by STI process steps as previously described.

According to one embodiment of the present disclosure, the second vertical diffuser plate 210 is a silicon active region defined and isolated by the first and second STI structures 104 and 105. Likewise, the second vertical diffusion plate 210 may be a P-type doped or N-type doped silicon region according to an embodiment of the present disclosure. For example, P-type dopants such as boron or N-type dopants such as phosphorus may be implanted into the silicon active regions defined and isolated by the first and second STI structures 104 and 105 by performing an ion well implantation process using a suitable hard mask, which is typically performed to form an ion well in the CMOS logic circuit region, thereby forming the first and second vertical diffusion plates 110 and 210. Such as P may be formed at the surface of the second vertical diffusion plate 210⁺Region or N⁺Heavily doped regions 211 of the region.

According to an embodiment of the present disclosure, the second vertical diffusion plate 210 further includes a lower portion 210a as a portion of the semiconductor substrate 100. As can be seen in fig. 2, the lower portion 210a may be wider than an upper covered portion of the second vertical diffuser plate 210 surrounded by the second STI structure 105. According to one embodiment of the present disclosure, lower portion 210a is surrounded and electrically isolated by outer wafer backside trench isolation structure 505 and inner wafer backside trench isolation structure 504. According to one embodiment of the present disclosure, the wafer backside trench isolation structure 505 has a ring shape that is substantially the same as the ring shape of the second STI structure 105. According to one embodiment of the present disclosure, the wafer backside trench isolation structure 505 is in direct contact with the bottom of the second STI structure 105.

According to one embodiment of the present disclosure, wafer backside trench isolation structures 505 are formed by filling wafer backside trenches with an insulating layer 500. According to one embodiment of the present disclosure, the insulating layer 500 may be formed by a Chemical Vapor Deposition (CVD) method including, but not limited to, a plasma enhanced CVD (pecvd), a low pressure CVD (lpcvd), a rapid thermal CVD (rtcvd), or an Atomic Layer Deposition (ALD) method. For example, the insulating layer 500 may include silicon oxide, silicon nitride, and silicon oxynitride, but is not limited thereto.

According to one embodiment of the present disclosure, as can be seen in FIG. 2, capacitor C₁A (Si-Si capacitor) may be formed between the first vertical diffuser plate 110 and the second vertical diffuser plate 210 with the annular first STI structures 104 and the wafer backside trench isolation structures 504 interposed therebetween serving as a capacitor dielectric layer. A plurality of first contact elements CT₁May be provided on the first vertical diffusion plate 110. Through a plurality of first contact elements CT₁And a metal interconnection 410, the first vertical diffusion plate 110 may be electrically coupled to a cathode node of the capacitor structure 1, which is supplied with a first voltage. A plurality of second contact elements CT₂May be provided on the second vertical diffusion plate 210. Via a plurality of second contact elements CT₂And a metal interconnection 420, the second vertical diffusion plate 210 may be electrically coupled to an anode node of the capacitor structure 1, which is supplied with a second voltage. According to one embodiment of the present disclosure, the second voltage may be higher than the first voltageAnd (6) pressing.

According to one embodiment of the present disclosure, passive elements 302 and 304, such as resistors, may be formed on the top surface of the first STI structure 104, and passive elements 306, such as resistors, may be formed on the top surface of the second STI structure 105. According to an embodiment of the present disclosure, the passive elements 302, 304, and 306 may be composed of polysilicon, but are not limited thereto. According to one embodiment of the present disclosure, the passive elements 302, 304, and 306 are formed only on the first and second STI structures 104 and 105, respectively. It should be understood that the layout and number of passive elements 302, 304, and 306 shown in fig. 1 are for illustration purposes only.

According to an embodiment of the present disclosure, the capacitor structure 1 may further include a third vertical diffusion plate 120 surrounding the second STI structures 105, the second vertical diffusion plate 210, the first STI structures 104, and the first vertical diffusion plate 110. When viewed from above, as can be seen in fig. 1, the third vertical diffuser plate 120 is an annular structure that surrounds the annular second STI structures 105. The third vertical diffuser plate 120 is defined and isolated by the second STI structures 105 and the outer third STI structures 106. The third STI structure 106 is also an annular trench isolation that electrically isolates the third vertical diffuser plate 120. The third STI structure 106 may be formed by STI process steps as previously described. According to one embodiment of the present disclosure, the third STI structures 106, the third vertical diffuser plate 120, the second STI structures 105, the second vertical diffuser plate 210, and the first STI structures 104 are disposed concentrically with the innermost first vertical diffuser plate 110.

According to one embodiment of the present disclosure, the third vertical diffuser plate 120 is a silicon active region defined and isolated by the second STI structures 105 and the third STI structures 106. Likewise, the third vertical diffusion plate 120 may be a P-type doped or N-type doped silicon region according to an embodiment of the present disclosure. For example, by performing an ion-well implantation process using a suitable hard mask (which is typically performed to form an ion well in the CMOS logic circuit region), P-type dopants such as boron or N-type dopants such as phosphorus may be implanted into the silicon active region defined and isolated by the second and third STI structures 105, 106 to form the first and second vertical diffusion plates 110, 106A straight diffuser plate 210 and a third vertical diffuser plate 120. Such as P⁺Region or N⁺A heavily doped region 121 of the region may be formed at a surface of the third vertical diffusion plate 120.

According to an embodiment of the present disclosure, the third vertical diffusion plate 120 further includes a lower portion 120a as a portion of the semiconductor substrate 100. As can be seen in fig. 2, the lower portion 120a may be wider than an upper covered portion of the second vertical diffuser plate 120 surrounded by the third STI structure 106. According to one embodiment of the present disclosure, lower portion 120a is surrounded and electrically isolated by outer wafer backside trench isolation structure 506 and inner wafer backside trench isolation structure 505. According to one embodiment of the present disclosure, the wafer backside trench isolation structure 506 has a ring shape that is substantially the same as the ring shape of the third STI structure 106. According to one embodiment of the present disclosure, the wafer backside trench isolation structure 506 is in direct contact with the bottom of the third STI structure 106.

According to one embodiment of the present disclosure, wafer backside trench isolation structures 506 are formed by filling the wafer backside trenches with an insulating layer 500. According to one embodiment of the present disclosure, the insulating layer 500 may be formed by a Chemical Vapor Deposition (CVD) method including, but not limited to, a plasma enhanced CVD (pecvd), a low pressure CVD (lpcvd), a rapid thermal CVD (rtcvd), or an Atomic Layer Deposition (ALD) method. For example, the insulating layer 500 may include silicon oxide, silicon nitride, and silicon oxynitride, but is not limited thereto.

According to one embodiment of the present disclosure, as can be seen in FIG. 2, capacitor C₂A (Si-Si capacitor) may be formed between the second vertical diffuser plate 210 and the third vertical diffuser plate 120 with the annular second STI structures 105 and the wafer backside trench isolation structures 505 interposed therebetween serving as a capacitor dielectric layer. A plurality of third contact elements CT₃May be provided on the third vertical diffusion plate 120. Via a plurality of third contact elements CT₃And a metal interconnection 410, the third vertical diffusion plate 120 may be electrically coupled to a cathode node of the capacitor structure 1, which is supplied with the first voltage. Thus, according to one embodiment of the present disclosure, as can be seen in fig. 2, a first vertical diffusionBoth the plate 110 and the third vertical diffuser plate 120 are electrically coupled to the cathode node.

According to one embodiment of the present disclosure, a passive element 308, such as a resistor, may be formed on the top surface of the third STI structure 106. According to an embodiment of the present disclosure, the passive element 308 may be composed of polysilicon, but is not limited thereto. According to one embodiment of the present disclosure, the passive element 308 is formed only on the third STI structure 106. It should be understood that the layout and number of passive elements 308 shown in fig. 1 are for illustration purposes only.

According to an embodiment of the present disclosure, the capacitor structure 1 may further include a fourth vertical diffusion plate 220, the fourth vertical diffusion plate 220 surrounding the third STI structures 106, the third vertical diffusion plate 120, the second STI structures 105, the second vertical diffusion plate 210, the first STI structures 104, and the first vertical diffusion plate 110. When viewed from above, as can be seen in fig. 1, the fourth vertical diffuser plate 220 is an annular structure that surrounds the annular third STI structure 106. The fourth vertical diffuser plate 220 is defined and isolated by the third STI structure 106 and the fourth STI structure 107. The fourth STI structure 107 is also an annular trench isolation that electrically isolates the fourth vertical diffuser plate 220. The fourth STI structure 107 may be formed by STI process steps as previously described. According to one embodiment of the present disclosure, the fourth STI structure 107, the fourth vertical diffuser plate 220, the third STI structure 106, the third vertical diffuser plate 120, the second STI structure 105, the second vertical diffuser plate 210, and the first STI structure 104 are arranged concentrically with the innermost first vertical diffuser plate 110.

According to one embodiment of the present disclosure, the fourth vertical diffuser plate 220 is a silicon active region defined and isolated by the third STI structure 106 and the fourth STI structure 107. According to an embodiment of the present disclosure, the fourth vertical diffusion plate 220 may also be a P-type doped or N-type doped silicon region. For example, by performing an ion-well implantation process using a suitable hard mask, which is typically performed to form an ion well in the CMOS logic circuit region, P-type dopants such as boron or N-type dopants such as phosphorus may be implanted into the silicon active region defined and isolated by the third and fourth STI structures 106 and 107, thereby forming the first vertical diffusion plate 110. A second vertical diffuser plate 210, a third vertical diffuser plate 120, and a fourth vertical diffuser plate 220. Such as P⁺Region or N⁺A heavily doped region 221 of the region may be formed at a surface of the fourth vertical diffusion plate 220.

According to one embodiment of the present disclosure, the fourth vertical diffusion plate 220 further includes a lower portion 220a as a portion of the semiconductor substrate 100. As can be seen in fig. 2, the lower portion 220a may be wider than an upper covered portion of the fourth vertical diffuser plate 220 surrounded by the fourth STI structure 107. According to one embodiment of the present disclosure, lower portion 220a is surrounded and electrically isolated by outer wafer backside trench isolation structure 507 and inner wafer backside trench isolation structure 506. According to one embodiment of the present disclosure, the wafer backside trench isolation structure 507 has a ring shape that is substantially the same as the ring shape of the fourth STI structure 107. According to one embodiment of the present disclosure, the wafer backside trench isolation structure 507 is in direct contact with the bottom of the fourth STI structure 107.

According to one embodiment of the present disclosure, the wafer backside trench isolation structure 507 is formed by filling the wafer backside trench with an insulating layer 500. According to one embodiment of the present disclosure, the insulating layer 500 may be formed by a Chemical Vapor Deposition (CVD) method including, but not limited to, a plasma enhanced CVD (pecvd), a low pressure CVD (lpcvd), a rapid thermal CVD (rtcvd), or an Atomic Layer Deposition (ALD) method. For example, the insulating layer 500 may include silicon oxide, silicon nitride, and silicon oxynitride, but is not limited thereto.

According to one embodiment of the present disclosure, as can be seen in FIG. 2, capacitor C₃A (Si-Si capacitor) may be formed between the third vertical diffuser 120 and the fourth vertical diffuser 220 with the annular third STI structures 106 and the wafer backside trench isolation structures 506 interposed therebetween to serve as a capacitor dielectric layer. A plurality of fourth contact elements CT₄May be provided on the fourth vertical diffusion plate 220. Via a plurality of fourth contact elements CT₄And a metal interconnection 420, the fourth vertical diffusion plate 220 may be electrically coupled to the anode node of the capacitor structure 1, which is supplied with the second voltage. Thus, according to one embodiment of the present disclosure, as in fig. 2As can be seen, both the second vertical diffuser plate 210 and the fourth vertical diffuser plate 220 are electrically coupled to the anode node.

According to one embodiment of the present disclosure, a passive element 310, such as a resistor, may be formed on the top surface of the fourth STI structure 107. According to an embodiment of the present disclosure, the passive element 310 may be composed of polysilicon, but is not limited thereto. According to one embodiment of the present disclosure, the passive element 310 is formed only on the fourth STI structure 107. It should be understood that the layout and number of passive elements 310 shown in fig. 1 are for illustration purposes only.

Structurally, the capacitor structure 1 includes a semiconductor substrate 100, a first vertical diffusion plate 110 disposed in the semiconductor substrate 100, a first Shallow Trench Isolation (STI) structure 104 disposed in the semiconductor substrate 100 and surrounding the first vertical diffusion plate 110, and a second vertical diffusion plate 210 disposed in the semiconductor substrate 100 and surrounding the first STI structure 104. The first vertical diffusion plate 110 further includes a first lower portion 110a as a portion of the semiconductor substrate 100. The first lower portion 110a is surrounded and electrically isolated by a first wafer backside trench isolation structure 504.

According to some embodiments, the first wafer backside trench isolation structure 504 is in direct contact with the bottom of the first STI structure 104.

According to some embodiments, the lateral thickness t of the first wafer backside trench isolation structure 504 is less than the lateral thickness of the first STI structure 104.

According to some embodiments, the first wafer backside trench isolation structure 504 has a ring shape that is substantially the same as the ring shape of the first STI structure 104.

According to some embodiments, the first vertical diffusion plate 110 is a P-type doped or N-type doped region.

According to some embodiments, the second vertical diffusion plate 210 is a P-type doped or N-type doped region.

According to some embodiments, the capacitor structure 1 further comprises an insulating layer 500 disposed on the back surface 100b of the semiconductor substrate 100.

According to some embodiments, the first STI structures 104 and the first wafer backside trench isolation structures 504 isolate the first vertical diffuser plate 110 from the second vertical diffuser plate 210.

According to some embodiments, the first vertical diffuser plate 110 is electrically coupled to a first voltage and the second vertical diffuser plate 210 is electrically coupled to a second voltage, wherein the second voltage is higher than the first voltage.

According to some embodiments, the capacitor C₁Formed between the first vertical diffuser plate 110 and the second vertical diffuser plate 210 with the first STI structures 104 and the first wafer backside trench isolation structures 504 interposed therebetween serving as capacitor dielectric layers.

According to some embodiments, the capacitor structure 1 further includes a first heavily doped region 111 disposed at a surface of the first vertical diffusion plate 110, and a second heavily doped region 211 disposed at a surface of the second vertical diffusion plate 210.

According to some embodiments, the capacitor structure 1 further comprises a second Shallow Trench Isolation (STI) structure 105 disposed in the semiconductor substrate 100. The second STI structure 105 surrounds the second vertical diffuser plate 210, the first STI structure 104, and the first vertical diffuser plate 110.

According to some embodiments, the second vertical diffusion plate 210 further includes a second lower portion 210a as a portion of the semiconductor substrate 100.

According to some embodiments, the second lower portion 210a is surrounded and electrically isolated by the second wafer backside trench isolation structure 505 and the first wafer backside trench isolation structure 504.

According to some embodiments, the second STI structure 105, the second vertical diffuser plate 210, the first STI structure 104 are arranged concentrically with the first vertical diffuser plate 110.

According to some embodiments, the first and second vertical diffuser plates 110 and 210 are silicon active regions defined and isolated by the first and second STI structures 104 and 105.

According to some embodiments, the capacitor structure 1 further comprises passive elements 302, 306 directly on the top surface of the first STI structure 104 or the second STI structure 105.

According to some embodiments, the passive elements 302, 306 comprise resistors. According to some embodiments, the passive elements 302, 306 comprise polysilicon.

According to some embodiments, the capacitor structure 1 further includes a third vertical diffuser 120 surrounding the second STI structure 105, the second vertical diffuser 210, the first STI structure 104, and the first vertical diffuser 110, and a third Shallow Trench Isolation (STI) structure 106 surrounding the third vertical diffuser 120, the second STI structure 105, the second vertical diffuser 210, the first STI structure 104, and the first vertical diffuser 110.

According to some embodiments, the capacitor structure 1 further includes a fourth vertical diffuser plate 220 surrounding the third STI structure 106, the third vertical diffuser plate 120, the second STI structure 105, the second vertical diffuser plate 210, the first STI structure 104, and the first vertical diffuser plate 110, and a fourth Shallow Trench Isolation (STI) structure 107 surrounding the fourth vertical diffuser plate 220, the third STI structure 106, the third vertical diffuser plate 120, the second STI structure 105, the second vertical diffuser plate 210, the first STI structure 104, and the first vertical diffuser plate 110.

According to some embodiments, the second vertical diffuser plate 210, the fourth vertical diffuser plate 220, and the ion trap 101 are electrically coupled to an anode node, and the first vertical diffuser plate 110 and the third vertical diffuser plate 120 are electrically coupled to a cathode node.

According to some embodiments, the semiconductor substrate 100 is a silicon substrate.

Please refer to fig. 3 to 5. Fig. 3-5 are schematic cross-sectional views illustrating an exemplary method for fabricating a capacitor structure according to another embodiment of the present disclosure, wherein like regions, layers or elements are denoted by like reference numerals.

As shown in fig. 3, P2 regions of a semiconductor substrate 100, such as a P-type silicon substrate, are subjected to an STI process as previously described, thereby forming alternating concentric rings of active regions and concentric rings of STI structures alternately interposed between the rings of active regions. For example, the innermost first vertical diffuser plate 110 is surrounded by the first STI structure 104, the second vertical diffuser plate 210, the second STI structure 105, the third vertical diffuser plate 120, the third STI structure 106, the fourth vertical diffuser plate 220, and the outermost fourth STI structure 107. A patterned polysilicon layer is formed over the STI structure. The patterned polysilicon layer may form passive components, such as passive components 302-310.

After the passive components 302-310 are formed, a dielectric layer 520 may be deposited on the front surface 100a of the semiconductor substrate 100. Such as contact plugs (e.g., contact plug CT described previously)₁～CT₄) May be formed in or on dielectric layer 520, as well as metal lines/traces such as interconnects 410 or 420 described previously. For simplicity, only one dielectric layer 520 is shown. However, it should be understood that the dielectric layer 520 may comprise multiple layers of dielectric material, or the like. The second vertical diffuser plate 210, the fourth vertical diffuser plate 220, and the ion trap 101 are electrically coupled to the anode node, and the first vertical diffuser plate 110 and the third vertical diffuser plate 120 are electrically coupled to the cathode node, through the interconnect structure.

The P2 region of the semiconductor substrate 100 may be subjected to a plurality of ion implantation processes to form a P-type or N-type doped first vertical diffusion plate 110, a P-type or N-type doped second vertical diffusion plate 210, a P-type or N-type doped third vertical diffusion plate 120, a P-type or N-type doped fourth vertical diffusion plate 220, and heavily doped regions 111, 121, 211, 221.

As shown in fig. 4, the semiconductor substrate 100 may then be flipped and then a wafer thinning process may be performed on the backside 100b to remove a portion of the semiconductor substrate 100 from the backside 100 b. Wafer backside thinning processes are well known in the art and will not be described in further detail herein. For example, the front surface 100a of the semiconductor substrate 100 may be adhered to a carrier substrate (not shown), and then the back surface 100b is polished or ground by a wafer polishing method known in the art.

As shown in FIG. 5, wafer backside trench isolation structures 504-507 are formed on the backside 100b of the semiconductor substrate 100 by using a technique such as a substrate contact (TSC) process. For example, first, concentric annular trenches are formed in the semiconductor substrate 100 by photolithography and etching processes. Subsequently, an insulating layer 500 is deposited on the back surface 100b of the semiconductor substrate 100, and the concentric annular trenches are filled with the insulating layer 500.

Those skilled in the art will readily observe that numerous modifications and alterations of the apparatus and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the scope and metes of the following claims.