Preparation method of TSV adapter plate with through hole and through cavity structure

Abstract

The invention discloses a method for manufacturing a TSV (Through Silicon Via) adapter plate with a through hole and through cavity structure. The method comprises the following steps of: photoetching: carrying out graphical photoetching treatment on the surface of a silicon substrate; photoetching patterns are a through hole pattern and an annular groove cavity pattern, and the groove width is matched with the diameter of the through hole; blind hole and blind cavity synchronous etching: blind hole and blind groove cavity etching is synchronously carried out by adopting a Bosch process, and the etching is stopped after the required depth is reached at the nearly same speed; thinning and polishing: removing the redundant silicon material on the back surface by using thinning equipment, and exposing the through hole and the through cavity structure; polishing equipment is used for polishing the back surface, so that the surface roughness is reduced, and the surface flatness is improved; and manufacturing a surface wiring layer: performing double-sided insulation deposition, double-sided seed layer sputtering and double-sided photoetching on the silicon substrate with the through hole / through cavity structure, electroplating the wiring layer, and removing metal of the seed layer to form the single-layer TSV adapter plate with the through hole and through cavity structure.

Description

Technical Field

[0001] The present invention relates to the field of TSV substrate manufacturing, and in particular to a method for preparing a TSV adapter plate with a through-hole and through-cavity structure. Background Art

[0002] With the advancement of semiconductor technology, monolithic integration technology is reaching its limits, hindering the miniaturization, integration, multi-functionality, and low power requirements of integrated circuits (ICs). Three-dimensional integration technology based on TSV (Through Silicon Via) technology enables integration and data transmission between homogeneous or heterogeneous chips, increasing the integration density of integrated circuits and becoming a key driver of Moore's Law. From a structural perspective, TSV interposers are primarily categorized into two types: blind-via-based TSV fabrication and through-via-based TSV fabrication. Through-via TSV interposers are thicker and feature a simpler process. They offer advantages such as high-density integration, strong mechanical support, deep cavities, and high production efficiency, and hold broad application prospects in fields such as RF microsystems and optoelectronic integration.

[0003] In advanced packaging fields such as RF microsystems, increasing integration requires embedding chips, resistors, capacitors, and other components within a three-dimensional packaging structure based on a TSV adapter plate. Therefore, the TSV adapter plate must not only enable electrical interconnection but also possess a cavity structure for embedding chips and other components. Patent CN 105428309A describes a process for fabricating blind cavities or TSV vias of various depths. This process involves first creating a blind cavity, then metallizing the cavity, thinning the surface to expose the silicon, and then fabricating a via on the silicon surface. However, this method is only suitable for blind cavity structures and cannot fabricate through-cavity structures. The hole size in a TSV adapter plate is generally small, while the cavity size is large. Due to the etching load effect, the simultaneous etching rates of the hole and cavity can differ significantly, resulting in a significant difference in depth for the same etching time. If a backside barrier layer is used to simultaneously fabricate the via and cavity, the excessively fast etch rate at the cavity location can cause lateral etching and substrate damage. Therefore, conventional methods make it difficult to simultaneously fabricate both vias and cavities. Another method is to first make a through-hole structure and then make a through-cavity after completing the surface wiring. This process route is complicated and the through-hole structure cannot be directly adsorbed in the etching equipment. It needs to be attached to the carrier and then etched, which is prone to quality problems such as glue sticking and contamination.

[0004] Therefore, how to simultaneously fabricate through-hole and through-cavity structures on a single substrate while ensuring good sidewall verticality, a simple process route, and high yield is a difficult problem in the fabrication of through-hole TSV adapter boards with through-cavities. Summary of the Invention

[0005] In response to the problems existing in the prior art, the present invention provides a method for realizing the production of a TSV adapter plate with a through-hole and through-cavity structure, solving the problem of the etching load effect caused by excessive difference in the area of ​​the etched patterns, realizing nearly the same rate etching of the hole and the cavity, effectively solving the influence of the etching load effect, being able to avoid multiple step-by-step etching, and avoiding the risk of glue sticking easily caused by post-cavity etching, effectively solving the influence of the etching load effect caused by the difference in the hole and cavity area, and being able to significantly improve production efficiency and product yield. It can be applied to the preparation method of TSV adapter plates with through-hole and through-cavity structures in the fields of RF microwave components, advanced packaging substrate manufacturing, etc.

[0006] The purpose of the present invention is achieved through the following technical solutions.

[0007] A method for manufacturing a TSV adapter plate having a through-hole and through-cavity structure, comprising the following steps:

[0008] Photolithography: Patterning photolithography is performed on the surface of the silicon substrate, including spin-on, pre-baking, exposure, development, and hardening steps. The pattern of the photolithography is a through-hole pattern and an annular groove pattern, and the groove width matches the through-hole diameter;

[0009] Simultaneous etching of blind vias and blind cavities: The Bosch process is used to simultaneously etch blind vias and blind groove cavities, and the etching is stopped after reaching the required depth at nearly the same rate. There are requirements for the etching rate, etching verticality, and etching selectivity of the two structures, and the load effect between different structures must be fully considered;

[0010] Thinning and polishing: Use thinning equipment to remove excess silicon material on the back to expose the through-hole and through-cavity structure. There are requirements for thinning thickness, TTV, etc. Use polishing equipment to polish the back to reduce surface roughness and improve surface flatness.

[0011] Surface wiring layer production: After double-sided insulation deposition, double-sided seed layer sputtering, and double-sided photolithography on a silicon substrate with a through-hole / through-cavity structure, the wiring layer is electroplated and the seed layer metal is removed to form a single-layer TSV adapter board with a through-hole and through-cavity structure.

[0012] The silicon substrate is cleaned before the photolithography step: the silicon substrate is cleaned according to the RCA cleaning method.

[0013] After the blind hole and blind cavity synchronous etching step, the process of stripping is performed: a special photoresist stripping solution is used to remove the photoresist remaining after etching, thereby obtaining a silicon substrate with patterned blind holes and blind groove cavities.

[0014] The silicon substrate is cleaned by first using SC-1 cleaning solution, NH4OH:H2O2:H2O=1:1:5, to undercut and remove surface particles by oxidation and micro-etching; secondly using SC-2 cleaning solution HCI:H2O2:H2O=1:1:6 to remove metal contaminants; then using SC-3 cleaning solution H2SO4:H2O2=5:1 to remove organic contaminants; and finally rinsing with DI water to complete the cleaning.

[0015] The photolithography steps specifically include: fabricating a cavity pattern mask plate. The pattern of the cavity pattern mask plate corresponds to the through-hole pattern and cavity pattern of the TSV. The cavity pattern is a ring-shaped structure corresponding to the cavity edge, and the groove width needs to match the through-hole diameter. Spin-coating photoresist (AZ4620) on the front side of the silicon substrate at a maximum spin speed of 2500 rpm / s and a thickness of 6-8μm. After pre-baking, the photoresist is exposed. The exposure time can be adjusted according to the thickness of the photoresist and the light intensity of the exposure machine. Development is then performed using 2.38% TMAH. Finally, the photoresist is hardened to obtain a patterned cavity pattern etch mask.

[0016] The simultaneous blind via and blind cavity etching steps are as follows: A photolithographically processed silicon substrate is placed directly into the etching equipment, and the through-holes and through-cavities are simultaneously etched using the Bosch process, which alternates between etching and protection. The process chamber pressure is 50 mT, and the protective gas is C4F8 at a flow rate of 150 sccm. The protection process lasts for 2 seconds. The etching is divided into two steps, etch1 and etch2, using SF6 at a gas flow rate of 200 sccm. Etch1 lasts for 1 second, with a lower electrode power of 100 W. Etch2 lasts for 3 seconds, with a lower electrode power of 40 W. Each protection and two etching steps constitute a cycle, with a total of 500 cycles, achieving blind vias and blind groove cavities with a depth of 420 μm.

[0017] The thinning and polishing steps are specifically as follows: first, a thinning device is used to remove most of the silicon material on the back side, the thickness of the remaining silicon substrate is controlled within 410 μm, and the structure of the holes and cavities is exposed from the back side; then, a polishing device is used to perform high-precision polishing on the back side, while reducing the roughness of the copper surface to ≤50 nm and improving the flatness of the substrate surface to ≤5 μm.

[0018] The surface wiring layer production steps are specifically as follows: double-sided insulation deposition, double-sided seed layer sputtering, and double-sided photolithography are performed on a silicon substrate with a through-hole / through-cavity structure, followed by electroplating of the wiring layer, and then dry etching or wet etching to remove the electroplated copper layer and the adhesion layer, followed by removing the photoresist mask to complete the surface wiring production, and finally realizing the wiring production on the upper and lower surfaces of the TSV substrate to form a single-layer TSV adapter board with a through-hole / through-cavity structure.

[0019] Compared with the prior art, the advantages of the present invention are:

[0020] 1. Ability to meet the three-dimensional packaging requirements with embedded package structure: The silicon-based adapter board manufacturing process method of the present invention can realize the production of through-hole TSV adapter boards with through-hole and through-cavity structures, which have the characteristics of high integration density, high mechanical strength and high cavity depth, and are adapted to the three-dimensional packaging requirements with embedded package structure.

[0021] 2. Low cost and high efficiency: The process method of the present invention is used to simultaneously produce the through hole and the through cavity structure, avoiding multiple step-by-step etching and reducing the process. In addition, this method can prepare a transfer plate with a high cavity depth, which can reduce the number of thin-layer transfer plates used and greatly reduce production costs.

[0022] 3. High production yield: The process method of the present invention eliminates the need for cavity etching after metallization, effectively avoiding problems such as carrier adhesion layer contamination, poor heat dissipation, and easy glue sticking caused by post-cavity opening, and significantly improves production yield.

[0023] 4. High process compatibility: By adopting the process method of the present invention, by changing the cavity etching to the annular groove cavity etching, the load effect encountered in the simultaneous etching of large-area cavity and small-size hole is avoided, and the simultaneous etching of cavity and hole of arbitrary pattern can be realized.

[0024] The present invention is a novel method for manufacturing a through-hole TSV adapter plate with low cost, high yield and wide applicability, and has high application value and economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a process flow chart for manufacturing a TSV adapter board with through-hole and through-cavity structures;

[0026] Figure 2 It is a schematic diagram of the structure of forming blind holes and annular groove patterns after photolithography on a silicon substrate;

[0027] Figure 3 It is a schematic diagram of the structure in which blind holes and annular grooves are formed after etching of a silicon substrate;

[0028] Figure 4 It is a schematic diagram of the cross-sectional structure of the blind hole and the annular groove cavity after the silicon substrate is debonded;

[0029] Figure 5 It is a schematic diagram of the top view structure of the blind hole and the annular groove cavity after the silicon substrate is debonded;

[0030] Figure 6 It is a schematic diagram of the cross-sectional structure of through holes and through cavities formed after thinning and polishing on the back side of the silicon substrate;

[0031] Figure 7 It is a schematic diagram of the top view structure of through holes and through cavities formed after thinning and polishing the back side of the silicon substrate;

[0032] Figure 8 It is a schematic diagram of the structure of the TSV adapter board formed after double-sided wiring on the silicon substrate;

[0033] In the figure: 1-silicon substrate; 2-photoresist; 3-blind hole; 4-groove cavity; 5-through hole; 6-through cavity; 7-wiring layer. DETAILED DESCRIPTION

[0034] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] For TSV adapter boards with both through-hole and through-cavity structures, the conventional process route is to first prepare through-holes on the wafer, then perform metallization on the surface and inside the holes, and finally etch out the through-cavity structure. This method has a long process route, and the wafer with a through-hole structure cannot be directly adsorbed in the etching equipment. It needs to be mounted before it can be etched. There is a risk of glue sticking and contamination when etching the through-cavity later. The present invention innovatively proposes a process technology method for synchronous etching of through-holes and through-cavities. First, blind holes and blind cavities are etched synchronously and at nearly the same rate. After thinning the back side, a wafer with both through-hole and through-cavity structures is formed. After that, the metallization process is completed to realize the production of TSV adapter boards with through-hole and through-cavity structures. In addition, in order to solve the problem of etching load effect caused by excessive difference in etching pattern area, the overall cavity etching pattern is designed as an annular groove cavity pattern. By adjusting the groove width to match the etching rate, the hole and cavity are etched at nearly the same rate, which effectively solves the influence of the etching load effect. This method offers a simple process and utilizes an integrated etching structure, avoiding multiple, step-by-step etching steps and the risk of adhesive paste formation that can occur with post-cavity etching. The annular groove design within the cavity effectively mitigates the etching loading effect caused by variations in cavity area, significantly improving production efficiency and product yield. This method is applicable to the manufacturing of RF microwave components and advanced packaging substrates.

[0036] The present invention includes the following steps: 10) Silicon substrate cleaning: The silicon substrate is cleaned according to the RCA cleaning method. A 700μm thick silicon substrate is used for illustration purposes; in practice, silicon substrates of varying thicknesses can be used based on design requirements. First, an SC-1 cleaning solution (NH₄OH:H₂O₂:H₂O = 1:1:5) is used to undercut and remove surface particles through oxidation and micro-etching. Next, an SC-2 cleaning solution (HCl:H₂O₂:H₂O = 1:1:6) is used to remove metal contaminants. Finally, an SC-3 cleaning solution (H₂SO₄:H₂O₂ = 5:1) is used to remove organic contaminants. Finally, a DI water rinse completes the cleaning process.

[0037] 20) Blind hole and slot pattern lithography: A hole pattern mask is produced. The pattern of the hole pattern mask corresponds to the through-hole pattern and cavity pattern of the TSV. The cavity pattern is a ring structure corresponding to the cavity edge, and the slot width needs to match the through-hole diameter. Photoresist is spin-coated on the front of the silicon substrate. The photoresist model is AZ4620, with a maximum spin-coating speed of 2500 rpm / s and a thickness of 6-8μm. After pre-baking, the photoresist is exposed. The exposure time can be adjusted according to the thickness of the photoresist and the light intensity of the exposure machine. The photoresist is then developed using a 2.38% concentration of TMAH. Finally, the photoresist is hardened to obtain a patterned hole pattern etch mask. The schematic diagram is shown below. Figure 2 shown.

[0038] 30) Simultaneous etching of blind holes and slots: Place the photolithographic silicon substrate directly into the etching equipment, and use the Bosch process with alternating etching / protection to perform simultaneous etching of through holes and through cavities. The process chamber pressure is 50mT, the protective gas is C4F8, the flow rate is 150sccm, and the protection process time is 2s; the etching is divided into two steps, etch1 and etch2, respectively. The gas used is SF6, and the gas flow rate is 200sccm. The etch1 process time is 1s, and the loaded lower electrode power is 100W. The etch2 process time is 3s, and the loaded lower electrode power is 40W. Each protection and two etching processes constitute a cycle, and the total number of cycles is 500. A blind hole and blind slot cavity structure with a depth of 420μm can be achieved. The schematic diagram is shown as follows. Figure 3 shown.

[0039] 40) Removal: Use a special photoresist remover to remove the photoresist on the surface of the silicon substrate to obtain a silicon substrate with patterned blind holes and blind grooves, as shown in the schematic diagram. Figure 4 and Figure 5 shown.

[0040] 50) Backside thinning and polishing to form through-hole / through-cavity structure: The excess silicon material on the back side of the silicon substrate is subjected to high-precision thinning and polishing. First, a thinning device is used to remove most of the silicon material on the back side, and the thickness of the remaining silicon substrate is controlled within 410μm, and the hole and cavity structure is exposed from the back side. Then, a polishing device is used to perform high-precision polishing on the back side, while reducing the roughness of the copper surface (≤50nm) and improving the flatness of the substrate surface (≤5μm) to meet the requirements of subsequent wiring processes. The schematic diagram of the silicon substrate with through-hole / through-cavity structure after thinning and polishing is shown in the figure below. Figure 6 and Figure 7 shown.

[0041] 60) Fabrication of surface wiring layer: After double-sided insulation deposition, double-sided seed layer sputtering, and double-sided photolithography on a silicon substrate with a through-hole / through-cavity structure, the wiring layer is electroplated. The electroplated copper layer and adhesion layer are then removed by dry or wet etching. The photoresist mask is then removed to complete the surface wiring fabrication. Finally, the wiring fabrication on the upper and lower surfaces of the TSV substrate is realized, forming a single-layer TSV adapter board with a through-hole / through-cavity structure. The final structure is as follows: Figure 8 shown.

Claims

1. A method for manufacturing a TSV adapter plate with a through hole and a through cavity structure, characterized in that The following steps are involved: Photolithography: Patterning photolithography is performed on the surface of the silicon substrate, including spin-on, pre-baking, exposure, development, and hardening steps. The pattern of the photolithography is a through-hole pattern and an annular groove pattern, and the groove width matches the through-hole diameter; Simultaneous etching of blind vias and blind cavities: The Bosch process is used to simultaneously etch blind vias and blind groove cavities, and the etching is stopped after reaching the required depth at nearly the same rate. There are requirements for the etching rate, etching verticality, and etching selectivity of the two structures, and the load effect between different structures must be fully considered; Thinning and polishing: Use thinning equipment to remove excess silicon material on the back to expose the through-hole and through-cavity structure. There are requirements for thinning thickness and TTV. Use polishing equipment to polish the back to reduce surface roughness and improve surface flatness. Surface wiring layer production: After double-sided insulation deposition, double-sided seed layer sputtering, and double-sided photolithography on a silicon substrate with a through-hole / through-cavity structure, the wiring layer is electroplated and the seed layer metal is removed to form a single-layer TSV adapter board with a through-hole and through-cavity structure.

2. The method for manufacturing a TSV adapter board having a through hole and a through cavity structure according to claim 1, characterized in that The silicon substrate is cleaned before the photolithography step: the silicon substrate is cleaned according to the RCA cleaning method.

3. The method for manufacturing a TSV adapter board having a through hole and a through cavity structure according to claim 1, characterized in that After the blind hole and blind cavity synchronous etching step, the process of stripping is performed: a special photoresist stripping solution is used to remove the photoresist remaining after etching, thereby obtaining a silicon substrate with patterned blind holes and blind groove cavities.

4. The method for manufacturing a TSV adapter board having a through hole and a through cavity structure according to claim 2, characterized in that The silicon substrate is cleaned by first using SC-1 cleaning solution with a ratio of NH4OH:H2O2:H2O=1:1:5 to undercut and remove surface particles by oxidation and micro-etching; and secondly using SC-2 cleaning solution with a ratio of HCl:H2O2:H2O=1:1:6 to remove metal contaminants; Then use SC-3 cleaning solution H2SO4:H2O2=5:1 to remove organic pollutants; finally rinse with DI water to complete the cleaning.

5. The method for manufacturing a TSV adapter board having a through hole and a through cavity structure according to claim 1, characterized in that The photolithography steps specifically include: fabricating a cavity pattern mask plate. The pattern of the cavity pattern mask plate corresponds to the through-hole pattern and cavity pattern of the TSV. The cavity pattern is a ring-shaped structure corresponding to the cavity edge, and the groove width needs to match the through-hole diameter. Spin-coating photoresist (AZ4620) on the front side of the silicon substrate at a maximum spin speed of 2500 rpm / s and a thickness of 6-8μm. After pre-baking, the photoresist is exposed. The exposure time can be adjusted according to the thickness of the photoresist and the light intensity of the exposure machine. Development is then performed using 2.38% TMAH. Finally, the photoresist is hardened to obtain a patterned cavity pattern etch mask.

6. The method for manufacturing a TSV adapter board having a through hole and a through cavity structure according to claim 1, characterized in that The simultaneous blind via and blind cavity etching steps are as follows: A photolithographically processed silicon substrate is placed directly into the etching equipment, and the through-holes and through-cavities are simultaneously etched using the Bosch process, which alternates between etching and protection. The process chamber pressure is 50 mT, and the protective gas is C4F8 at a flow rate of 150 sccm. The protection process lasts for 2 seconds. The etching is divided into two steps, etch1 and etch2, using SF6 at a gas flow rate of 200 sccm. Etch1 lasts for 1 second, with a lower electrode power of 100 W. Etch2 lasts for 3 seconds, with a lower electrode power of 40 W. Each protection and two etching steps constitute a cycle, with a total of 500 cycles, achieving blind vias and blind groove cavities with a depth of 420 μm.

7. The method for manufacturing a TSV adapter board having a through hole and a through cavity structure according to claim 1, characterized in that The thinning and polishing steps are specifically as follows: first, a thinning device is used to remove most of the silicon material on the back side, the thickness of the remaining silicon substrate is controlled within 410 μm, and the structure of the holes and cavities is exposed from the back side; then, a polishing device is used to perform high-precision polishing on the back side, while reducing the roughness of the copper surface to ≤50 nm and improving the flatness of the substrate surface to ≤5 μm.

8. The method for manufacturing a TSV adapter board having a through hole and a through cavity structure according to claim 1, characterized in that The surface wiring layer production steps are specifically as follows: double-sided insulation deposition, double-sided seed layer sputtering, and double-sided photolithography are performed on a silicon substrate with a through-hole / through-cavity structure, followed by electroplating of the wiring layer, and then dry etching or wet etching to remove the electroplated copper layer and the adhesion layer, followed by removing the photoresist mask to complete the surface wiring production, and finally realizing the wiring production on the upper and lower surfaces of the TSV substrate to form a single-layer TSV adapter board with a through-hole / through-cavity structure.

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