阅读说明：本技术 一种dram芯片三维集成系统及其制备方法 (DRAM chip three-dimensional integrated system and preparation method thereof ) 是由 朱宝 陈琳 孙清清 张卫 于 2020-06-30 设计创作，主要内容包括：本发明公开了一种DRAM芯片三维集成系统及其制备方法。在硅片正反面刻蚀出若干个沟槽结构；然后,在上下相对的两个沟槽之间刻蚀出TSV结构进行电气连通；接着,在沟槽内放置DRAM芯片,并采用铜-铜键合的方式使得垂直方向上芯片与TSV结构电气连通；最后进行重布线,使得水平方向上的芯片之间电气连通。本发明能够充分利用硅材料,而且可以避免转接板出现翘曲、变形等问题。此外,将芯片放置在沟槽内,既不会增大整体封装厚度,又能保护芯片不会受到外力冲击。(The invention discloses a DRAM chip three-dimensional integrated system and a preparation method thereof. Etching a plurality of groove structures on the front side and the back side of the silicon wafer; then, etching a TSV structure between the two grooves which are opposite up and down to carry out electrical communication; then, a DRAM chip is placed in the groove, and the chip and the TSV structure are electrically communicated in the vertical direction in a copper-copper bonding mode; finally, rewiring is carried out, so that the chips in the horizontal direction are electrically communicated. The invention can make full use of silicon materials and can avoid the problems of warping, deformation and the like of the adapter plate. In addition, the chip is placed in the groove, the whole packaging thickness is not increased, and the chip can be protected from being impacted by external force.)

1. A three-dimensional integrated system of DRAM chips is characterized in that,

the method comprises the following steps:

a top trench, a bottom trench and a through-silicon-via through a silicon substrate (200), wherein the through-silicon-via connects the top trench and the bottom trench;

a first insulating dielectric (201), a first copper diffusion barrier layer (202), and a copper seed layer (203), wherein the first insulating dielectric (201) covers the bottom trench and is discontinuous at the bottom of the through silicon via; the first copper diffusion barrier layer (202) is formed on the first insulating medium (201); the copper seed layer (203) covers the first copper diffusion barrier layer (202) and exhibits a continuous thin film state; -the first copper diffusion barrier layer (202) and the copper seed layer (203) are disconnected at the connection area of adjacent bottom trenches for insulation;

a second insulating medium (204), a second copper diffusion barrier layer (205), a copper film (207) and a conductive copper pillar (206), wherein the second insulating medium (204) covers the top trench and the through silicon via and is in a discontinuous state at the bottom of the through silicon via; the second copper diffusion barrier layer (205) covers the second insulating medium (204); said copper film (207) covering said second copper diffusion barrier layer (205) within said top trench and presenting a continuous film state; the conductive copper pillar (206) covers the second copper diffusion barrier layer (205) on the side wall of the silicon through hole and completely fills the silicon through hole, the top of the conductive copper pillar is contacted with the copper film (207), and the bottom of the conductive copper pillar is contacted with the copper seed layer (203); -the second copper diffusion barrier layer (205) and the copper film (207) are disconnected at the connection area of adjacent top trenches for insulation;

a DRAM chip (208), a contact bump (209), a filler (210) and a rewiring layer (211), wherein the DRAM chip (208) is respectively bonded with the copper seed layer (203) and the copper film (207) through the contact bump (209); the filler (210) fills a gap between the DRAM chip (208) and the trench; the redistribution layer (211) covers the top and bottom of the three-dimensional integrated system.

2. The DRAM chip three-dimensional integrated system of claim 1,

the first insulating medium (201) and the second insulating medium (204) are SiO₂、Si₃N₄At least one of SiOCH and SiOCFH.

3. The DRAM chip three-dimensional integrated system of claim 1,

the first copper diffusion impervious layer (202) and the second copper diffusion impervious layer (205) are TaN, TiN, ZrN and MnSiO₃At least one of (1).

4. The DRAM chip three-dimensional integrated system of claim 1,

the filler (210) is epoxy resin.

5. A method for preparing a three-dimensional integrated system of a DRAM chip is characterized in that,

the method comprises the following steps:

photoetching and etching the front surface and the back surface of a monocrystalline silicon substrate (200) to form a top groove and a bottom groove;

depositing a first insulating medium (201), a first copper diffusion barrier layer (202) and a copper seed layer (203) in the bottom groove in sequence;

etching the silicon substrate between the top groove and the bottom groove to form a silicon through hole in a penetrating manner;

removing the first insulating medium (201) and the first copper diffusion barrier layer (202) at the bottom of the through silicon via, thereby exposing a copper seed layer (203); depositing a second insulating medium (204) and a second copper diffusion barrier layer (205) on the surface of the top groove and the surface of the silicon through hole in sequence;

removing the second insulating medium (204) and the second copper diffusion barrier layer (205) at the bottom of the through silicon via, thereby exposing the copper seed layer (203); electroplating a copper material on the surface of the copper seed layer (203) to completely fill the silicon through hole and be flush with the upper surface of a second copper diffusion barrier layer (205) positioned at the bottom of the top groove, thereby forming a conductive copper column (206); depositing a copper film (207) on the surface of the top groove;

removing the first copper diffusion barrier layer (202) and the copper seed layer (203) adjacent to the bottom trench connection region, and the second copper diffusion barrier layer (205) and the copper film (207) adjacent to the top trench connection region; bonding contact bumps (209) of the DRAM chip (208) with the copper seed layer (203) and the copper thin film (207), respectively; filling filler (210) in the gap between the DRAM chip (208) and the trench as a buffer layer and an isolation layer; a redistribution layer (211) is formed on the top and bottom of the structure so that the DRAM chips in the horizontal direction are electrically connected.

6. The method for fabricating a three-dimensional integrated system of DRAM chips as recited in claim 5,

the first insulating medium (201) and the second insulating medium (204) are SiO₂、Si₃N₄At least one of SiOCH and SiOCFH.

7. The method for fabricating a three-dimensional integrated system of DRAM chips as recited in claim 5,

the first copper diffusion impervious layer (202) and the second copper diffusion impervious layer (205) are TaN, TiN, ZrN and MnSiO₃At least one of (1).

8. The method for fabricating a three-dimensional integrated system of DRAM chips as recited in claim 5,

the filler (210) is epoxy resin.

Technical Field

The invention belongs to the field of integrated circuit packaging, and particularly relates to a DRAM chip three-dimensional integrated system and a preparation method thereof.

Background

With the rapid development of integrated circuit technology, microelectronic packaging technology is becoming a major factor that restricts the development of semiconductor technology. In order to achieve high density of electronic packages, better performance and lower overall cost, the skilled person has developed a series of advanced packaging techniques. The three-dimensional system-in-package technology has good electrical performance and high reliability, can realize high packaging density, and is applied to a Dynamic Random Access Memory (DRAM) chip system.

The Through Silicon Via (TSV) interposer technology is a new technology for realizing interconnection of stacked chips in a three-dimensional integrated circuit, and a plurality of vertical interconnection vias and subsequent Redistribution Layer (RDL) are manufactured on a Silicon wafer to realize electrical interconnection between different chips. The TSV adapter plate technology can enable the stacking density of DRAM chips in the three-dimensional direction to be the largest, the interconnection line between the chips to be the shortest and the overall dimension to be the smallest, greatly improves the performance of the storage density, the speed and the low power consumption of the chips, and is the most attractive technology in the current electronic packaging technology. However, in order to meet the requirement of the overall thickness of the package, the silicon wafer is usually thinned, then the TSV structure is fabricated, and finally the chips are stacked in the vertical direction. The thinning of the silicon wafer undoubtedly increases the process complexity, causes the waste of silicon materials and is easy to have the problem of warping deformation.

Disclosure of Invention

In order to solve the above problems, the present invention discloses a DRAM chip three-dimensional integrated system, comprising: a top trench, a bottom trench and a through-silicon-via through a silicon substrate, wherein the through-silicon-via connects the top trench and the bottom trench;

the first insulating medium covers the bottom groove and is discontinuous at the bottom of the silicon through hole; the first copper diffusion barrier layer is formed on the first insulating medium; the copper seed crystal layer covers the first copper diffusion impervious layer and presents a continuous film state; the first copper diffusion barrier layer and the copper seed layer are disconnected at the adjacent region of the bottom groove to realize insulation;

the second insulating medium covers the top groove and the side wall of the silicon through hole, and is in a discontinuous state at the top and the bottom of the silicon through hole; the second copper diffusion barrier layer is formed on the second insulating medium; the copper film covers the second copper diffusion impervious layer in the top groove and presents a continuous film state; the conductive copper pillar covers the second copper diffusion barrier layer on the side wall of the silicon through hole and completely fills the silicon through hole, the top of the conductive copper pillar is in contact with the copper film, and the bottom of the conductive copper pillar is in contact with the copper seed crystal layer; the second copper diffusion barrier layer and the copper film are disconnected at a region adjacent to the top trench to achieve insulation;

the DRAM chip is respectively bonded with the copper seed crystal layer and the copper film through the contact bumps; the filler fills gaps among the DRAM chip, the copper seed crystal layer and the copper film; the redistribution layer covers the top and bottom of the three-dimensional integrated system.

In the three-dimensional integrated system of DRAM chip of the present invention, preferably, the first insulating medium and the second insulating medium are SiO₂、Si₃N₄At least one of SiOCH and SiOCFH.

In the three-dimensional integrated system of the DRAM chip, preferably, the first copper diffusion barrier layer and the second copper diffusion barrier layer are TaN, TiN, ZrN and MnSiO₃At least one of (1).

In the three-dimensional integrated system of the DRAM chip of the present invention, preferably, the filler is an epoxy resin.

The invention also discloses a preparation method of the DRAM chip three-dimensional integrated system, which comprises the following steps: photoetching and etching the front side and the back side of a monocrystalline silicon substrate to form a top groove and a bottom groove; depositing a first insulating medium, a first copper diffusion barrier layer and a copper seed crystal layer in the bottom groove in sequence; etching the silicon substrate between the top groove and the bottom groove to form a silicon through hole in a penetrating manner;

removing the first insulating medium and the first copper diffusion impervious layer at the bottom of the through silicon via so as to expose the copper seed crystal layer; depositing a second insulating medium and a second copper diffusion barrier layer on the surface of the top groove and the surface of the silicon through hole in sequence; removing the second insulating medium and the second copper diffusion impervious layer which are positioned at the bottom of the through silicon via, so as to expose the copper seed crystal layer; electroplating a copper material on the surface of the copper seed crystal layer to completely fill the through silicon via and make the through silicon via flush with the upper surface of the second copper diffusion barrier layer positioned at the bottom of the top groove, so as to form a conductive copper column; depositing a copper film on the surface of the top groove;

removing the first copper diffusion barrier layer and the copper seed crystal layer in the adjacent bottom groove connecting area, and the second copper diffusion barrier layer and the copper film in the adjacent top groove connecting area; bonding the contact salient points of the DRAM chip with the copper seed crystal layer and the copper film respectively; filling filler in a gap between the DRAM chip and the groove to serve as a buffer layer and an isolation layer; and manufacturing a heavy wiring layer on the top and the bottom of the structure so that the DRAM chips in the horizontal direction are electrically communicated.

In the method for preparing the three-dimensional integrated system of the DRAM chip of the present invention, preferably, the first insulating medium and the second insulating medium are SiO₂、Si₃N₄At least one of SiOCH and SiOCFH.

In the preparation method of the DRAM chip three-dimensional integrated system, the first copper diffusion barrier layer and the second copper diffusion barrier layer are preferably TaN, TiN, ZrN and MnSiO₃At least one of (1).

In the method for preparing the three-dimensional integrated system of the DRAM chip, preferably, the filler is epoxy resin.

The invention can make full use of silicon materials and can avoid the problems of warping, deformation and the like of the adapter plate. In addition, the chip is placed in the groove, the whole packaging thickness is not increased, and the chip can be prevented from being impacted by external force.

Drawings

FIG. 1 is a flow chart of a method for fabricating a three-dimensional integrated system of DRAM chips.

Fig. 2 to 13 are schematic structural diagrams of steps of a method for manufacturing a three-dimensional integrated system of a DRAM chip.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more clearly and completely understood, the technical solutions in the embodiments of the present invention will be described below with reference to the accompanying drawings in the embodiments of the present invention, and it should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention. The described embodiments are only some embodiments of the invention, not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it should be noted that the terms "upper", "lower", "vertical", "horizontal", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience in describing the present invention and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

Furthermore, numerous specific details of the invention, such as structure, materials, dimensions, processing techniques and techniques of the devices are described below in order to provide a more thorough understanding of the invention. However, as will be understood by those skilled in the art, the present invention may be practiced without these specific details. Unless otherwise specified below, each part in the device may be formed of a material known to those skilled in the art, or a material having a similar function developed in the future may be used.

The technical solution of the present invention is further described below with reference to fig. 1 to 13 and the embodiments. Fig. 1 is a flow chart of a method for manufacturing a three-dimensional integrated system of a DRAM chip, and fig. 2 to 13 are schematic structural diagrams showing steps of the method for manufacturing a three-dimensional integrated system of a DRAM chip. As shown in fig. 1, the preparation method comprises the following specific steps:

in step S1, a trench is etched into the silicon substrate. First, a photoresist is spin-coated on the front and back sides of the single crystal silicon substrate 200 and the positions of the top and bottom trenches are defined through exposure and development processes. Then, a reactive ion etching process is used to etch the trench structure, and the resulting structure is shown in fig. 2. CF may be selected for the reactive plasma used to etch silicon substrate 200₄、SF₆At least one of (1). In the present embodiment, a reactive ion etching process is used to obtain the trench structure, but the present invention is not limited thereto, and at least one process of dry etching such as ion mill etching, plasma etching, reactive ion etching, laser ablation, or wet etching by using an etchant solution may be selected.

In step S2, a first insulating dielectric, a first copper diffusion barrier layer, and a copper seed layer are deposited in the bottom trench. Sequentially depositing SiO in the bottom groove by adopting a physical vapor deposition process₂The thin film, the TaN thin film and the Cu thin film are respectively used as the first insulating medium 201, the first copper diffusion barrier layer 202 and the copper seed layer 203, and the resulting structure is shown in fig. 3. SiO is used in the present embodiment₂The thin film is used as the first insulating medium, and TaN thin film is used as the first copper diffusion barrier layer, but the invention is not limited thereto, and SiO can be selected₂、Si₃N₄At least one of low dielectric constant materials (such as SiOCH, SiOCFH) is selected as the first insulating medium, TaN, TiN, ZrN, MnSiO₃As a first copper diffusion barrier.

In step S3, a through silicon via is etched between the top trench and the bottom trench. Firstly, spin-coating photoresist inside the top trench and defining the position of the through-silicon via through exposure and development processes. Then, a deep plasma etch (DRIE) process is used to etch the silicon between the top and bottom trenchesThe substrate 200 is etched until the first insulating medium 201 is contacted. Finally, the photoresist is dissolved or ashed away in a solvent, and the resulting structure is shown in FIG. 4. Wherein CF may be selected for the plasma used to etch the silicon substrate 200₄、SF₆At least one of (1). In the present embodiment, a deep reactive ion etching process is used to obtain the trench structure, but the present invention is not limited thereto, and at least one process of dry etching such as ion mill etching, plasma etching, reactive ion etching, deep reactive ion etching, laser ablation, or wet etching by using an etchant solution may be selected.

In step S4, a second insulating dielectric and a second copper diffusion barrier layer are deposited within the top trench and the through-silicon via. First, the first insulating medium 201 and the first copper diffusion barrier layer 202 located at the bottom of the through-silicon-via are removed by dry etching such as ion mill etching, plasma etching, reactive ion etching, laser ablation, or by a wet etching process using an etchant solution, thereby exposing the copper seed layer 203, and the resulting structure is shown in fig. 5. Then, sequentially depositing SiO on the surfaces of the top groove and the silicon through hole by adopting a chemical vapor deposition process₂The film and TaN film, as the second insulating dielectric 204 and the second copper diffusion barrier 205, respectively, the resulting structure is shown in fig. 6. Next, the second insulating medium 204 and the second copper diffusion barrier layer 205 at the bottom of the through-silicon-via are removed by dry etching such as ion mill etching, plasma etching, reactive ion etching, laser ablation, or by wet etching process using etchant solution, thereby exposing the copper seed layer 203, and the resulting structure is as shown in fig. 7. SiO is used in the present embodiment₂The thin film is used as the second insulating medium, and TaN thin film is used as the second copper diffusion barrier layer, but the invention is not limited to this, and SiO can be selected₂、Si₃N₄At least one of low dielectric constant materials (such as SiOCH and SiOCFH) is selected as the second insulating medium, TaN, TiN, ZrN, MnSiO₃As a second copper diffusion barrier.

In step S5, a conductive copper pillar is formed by electroplating in the through-silicon via, and a copper film is deposited in the top trench. First, a copper seed layer 203 is used as a seed layer, and an electroplating process is used to electroplate a copper material on the surface of the seed layer, wherein the copper material completely fills the through-silicon via and is flush with the upper surface of the second copper diffusion barrier layer 205 located at the bottom of the top trench, so that a conductive copper pillar 206 is formed, and the obtained structure is shown in fig. 8. Finally, a physical vapor deposition process is used to deposit a copper film 207 in the top trench, and the resulting structure is shown in FIG. 9.

In step S6, a DRAM chip is built into the trench and bonded and re-routed with the TSV structure. First, the first copper diffusion barrier layer 202 and the copper seed layer 203 in the adjacent bottom trench connection region, and the second copper diffusion barrier layer 205 and the copper film 207 in the top trench connection region are removed by photolithography and etching processes, and the resulting structure is shown in fig. 10. Further, a DRAM chip 208 with a copper contact bump 209 is placed inside the trench, and then copper-copper bonding is performed at a temperature of 300 to 400 ℃, that is, the copper contact bump 209 is bonded to the copper thin film 207 and the copper seed layer 203 respectively under heating conditions, and the resulting structure is as shown in fig. 11. Next, the gap between the DRAM chip 208 and the top and bottom trenches is filled with epoxy 210 as a buffer layer and an isolation layer, and the resulting structure is shown in fig. 12. Finally, redistribution layers 211 are fabricated on top and bottom of the above structure so that the DRAM chips in the horizontal direction are electrically connected, and the resulting structure is shown in fig. 13.

As shown in fig. 13, a three-dimensional integrated system of a DRAM chip of the present invention includes: a top trench, a bottom trench and a through-silicon-via through the silicon substrate 200, wherein the through-silicon-via connects the top trench and the bottom trench;

a first insulating medium 201, a first copper diffusion barrier layer 202 and a copper seed layer 203, wherein the first insulating medium 201 covers the bottom trench and is discontinuous at the bottom of the through silicon via; a first copper diffusion barrier layer 202 covers the first insulating medium 201; the copper seed layer 203 covers the first copper diffusion barrier layer 202 and exhibits a continuous thin film state; the first copper diffusion barrier layer 202 and the copper seed layer 203 are disconnected at the bottom trench adjacent region to achieve insulation;

a second insulating medium 204, a second copper diffusion barrier layer 205, a copper film 207 and a conductive copper pillar 206, wherein the second insulating medium 204 covers the top trench and the through silicon via and is in a discontinuous state at the top and the bottom of the through silicon via; a second copper diffusion barrier 205 covers the second insulating dielectric 204; the copper film 207 covers the second copper diffusion barrier layer 205 in the top trench and exhibits a continuous film state; the conductive copper pillar 206 covers the second copper diffusion barrier layer 205 on the sidewall of the through silicon via and completely fills the through silicon via, with its top in contact with the copper film 207 and bottom in contact with the copper seed layer 203; the second copper diffusion barrier 205 and the copper film 207 are disconnected at the top trench adjacent region to achieve insulation;

the DRAM chip 208, the contact bump 209, the filler 210 and the rewiring layer 211, wherein the DRAM chip 208 is respectively bonded with the copper seed layer 203 and the copper film 207 through the contact bump 209; the filler 210 fills the gap between the DRAM chip 208 and the copper seed layer 203 and the copper thin film 207; the redistribution layer 211 covers the top and bottom of the three-dimensional integrated system.

Preferably, the first insulating medium and the second insulating medium are SiO₂、Si₃N₄SiOCH, SiOCFH, and the like. The first copper diffusion impervious layer and the second copper diffusion impervious layer are TaN, TiN, ZrN and MnSiO₃At least one of (1). The filler is epoxy resin.

The silicon chip for manufacturing the adapter plate does not need to be thinned, so that the process steps can be reduced, the silicon material can be fully utilized, and the problems of warping and deformation of the adapter plate can be solved. In addition, the grooves are etched on the adapter plate, and the chips are placed in the grooves, so that the overall packaging thickness is not increased, and the chips can be protected from being impacted by external force. In addition, the TSV structure between the upper and lower two opposite grooves is utilized to realize the electrical communication of the DRAM chip in the vertical direction.

The above description is only for the specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.