Preparation method of bonding metal layer

Abstract

The invention provides a preparation method of a bonding metal layer, and the method comprises the steps: preparing a graphical mask which is made of a magnetic material; a first wafer is provided, a protrusion is arranged on the surface of the first wafer, and a magnetic backboard is arranged on the side, away from the protrusion, of the first wafer; the mask plate is attached to the partial surface of the protrusion through magnetic adsorption between the magnetic back plate and the mask plate; and a bonding material is deposited on the areas, not attached by the mask plate, of the protrusions through an evaporation process to form a bonding metal layer. According to the method, the graphical mask with the magnetic material is arranged, the magnetic back plate is arranged on the side, away from the protrusion, of the first wafer, the mask is attached to the partial surface of the protrusion through magnetic adsorption between the magnetic back plate and the mask, a complex mechanical positioning clamp or a multi-step calibration process does not need to be used, and the calibration efficiency is improved. The fixing operation of the mask plate is simplified, the protrusions play a role in supporting the attached mask plate, one-step forming of the bonding metal layer is achieved, and the technological process is simplified.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and more specifically to a method for preparing a bonding metal layer. Background Technology

[0002] MEMS sensors are a new type of sensor manufactured using microelectronics and micromachining technologies. They are characterized by small size, light weight, low cost, low power consumption, high reliability, high added value, suitability for mass production, ease of integration, and the ability to achieve intelligent operation.

[0003] However, in existing MEMS structure metal bonding processes, when setting bonding metal layers on wafer bumps through evaporation, the bonding operation between the mask and the bump structure is complicated, resulting in low efficiency. Summary of the Invention

[0004] The problem solved by this invention is that the bonding operation between the mask and the raised structure in the existing MEMS structure metal bonding process is complicated.

[0005] To address the above problems, the present invention provides a method for preparing a bonding metal layer, the method comprising: A patterned photomask is prepared, wherein the material of the photomask includes a magnetic material; A first wafer is provided, the surface of the first wafer is provided with protrusions, and a magnetic backplate is provided on the side of the first wafer away from the protrusions; The mask is attached to the raised portion surface by magnetic adsorption between the magnetic back plate and the mask. A bonding material is deposited on the area of ​​the protrusion that is not adhered to by the mask using a vapor deposition process to form a bonding metal layer.

[0006] Optionally, in a direction perpendicular to the first wafer, the first wafer is provided with an alignment groove, and the mask is provided with an alignment hole penetrating the mask. Before attaching the mask to the surface of the protruding portion, the fabrication method further includes: The mask is positioned relative to the protrusion by using a laser to pass through the alignment hole and the alignment groove.

[0007] Optionally, the preparation of the patterned mask includes: Provide a mask material layer; The mask material layer is patterned to form at least one first through-hole penetrating the mask material layer and a second through-hole surrounding the outer periphery of the first through-hole; The remaining mask material layer after patterning serves as a mask plate, which includes a first part and a second part surrounding the outer periphery of the first part. The first through hole penetrates the first part, and the second through hole is disposed around the first part and the second part.

[0008] Optionally, the protrusion includes annular protrusions and block-shaped protrusions located inside the annular protrusions, and the step of attaching the mask to a portion of the surface of the protrusions includes: The first portion is fitted to the side of the annular protrusion closest to the block protrusion, so that the first through hole corresponds to the block protrusion and the second through hole corresponds to the unfitted portion of the annular protrusion.

[0009] Optionally, in a direction perpendicular to the first wafer, the orthographic projection of the first via coincides with the orthographic projection of the block protrusion, or the orthographic projection of the block protrusion is located within the orthographic projection of the first via.

[0010] Optionally, the protrusion includes an annular protrusion and a block protrusion located inside the annular protrusion. In a direction perpendicular to the first wafer, the edge of the second through hole near the block protrusion coincides with the edge of the annular protrusion near the block protrusion, and / or the edge of the second through hole away from the block protrusion extends beyond the edge of the annular protrusion away from the block protrusion.

[0011] Optionally, a connecting support structure is formed between the first part and the second part, the diameter of which is between 80 nanometers and 100 nanometers.

[0012] Optionally, the step of depositing bonding material on the area of ​​the protrusion not adhered to by the mask through a vapor deposition process to form a bonding metal layer includes: The bonding material is heated and vaporized to form vaporized particles through a vapor deposition process. The vaporized particles are then deposited on the protrusion through the first and second through holes to form a bonding metal layer that matches the first and second through holes.

[0013] Optionally, the material of the mask includes at least one of iron, cobalt, and nickel.

[0014] Optionally, the material of the bonding metal layer includes at least one of Ge, Al, Au, Cu, and Sn.

[0015] Compared with the prior art, the technical solution of the embodiments of the present invention has the following advantages: 1. The bonding metal layer preparation method provided in this application embodiment uses a patterned mask with magnetic material and a magnetic backplate on the side of the first wafer away from the protrusion. The mask is attached to the surface of the protrusion by magnetic adsorption between the magnetic backplate and the mask. This eliminates the need for complex mechanical positioning fixtures or multi-step calibration processes, simplifying the fixing operation of the mask. At the same time, the protrusion can support the attached mask, and then the bonding material can be deposited in the unattached area by vapor deposition, achieving one-step forming of the bonding metal layer, further simplifying the process flow.

[0016] 2. The preparation method provided in this application involves attaching the first part of the mask to the side of the annular protrusion closest to the block protrusion, that is, attaching the first part of the mask to the inner side of the annular protrusion. In this way, the mask can be supported by the annular protrusion, and the inner side of the annular protrusion can be shielded by attaching the mask to the inner side of the annular protrusion. This avoids the bonding material deposited on the inner side of the bonding ring from overflowing into the working area during bonding, effectively reducing the risk of overflow and ensuring performance.

[0017] 3. In the preparation method provided in the embodiments of this application, the orthographic projection of the first through hole coincides with the orthographic projection of the block protrusion in the direction perpendicular to the first wafer. This setting allows the bonding material to be deposited on the top surface of the block protrusion through the first through hole during the evaporation of the bonding material, effectively avoiding the formation of bonding material residue on the sidewall of the block protrusion.

[0018] 4. The preparation method provided in this application embodiment uses a laser to position the mask and the protrusion before attaching the mask to the surface of the protrusion. This eliminates the need for complex mechanical calibration fixtures or multiple manual adjustments. The real-time feedback of the laser signal allows for rapid alignment and calibration of the mask and the protrusion, significantly shortening the positioning operation time. Furthermore, the laser positioning can be reused, reducing costs. Attached Figure Description

[0019] Figure 1 A schematic flowchart illustrating the method for preparing the bonding metal layer provided in this application embodiment; Figure 2 for Figure 1 The process flow diagram corresponding to the bonding method shown is shown below; Figure 3 for Figure 1 A schematic diagram of the process for preparing a patterned mask in the preparation method shown; Figure 4 This is a top view of the mask.

[0020] Explanation of reference numerals in the attached figures: 1. First wafer; 11. Bump; 12. Bonding metal layer; 13. Magnetic backplane; 14. Alignment groove; 2. Mask; 21. Alignment hole; 22. Mask material layer; 23. First through hole; 24. Second through hole; 25. First part; 26. Second part; 27. Connecting support structure; 111. Annular protrusion; 112. Block protrusion. Detailed Implementation

[0021] To make the above-mentioned objectives, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below.

[0022] Please see Figure 1 and Figure 2 , Figure 1 A schematic flowchart illustrating the method for preparing the bonding metal layer provided in this application embodiment; Figure 2 for Figure 1 The bonding method shown in the diagram corresponds to a process flow chart. This application embodiment provides a method for preparing a bonding metal layer 12, the method comprising: S110. Prepare a patterned mask, the material of which includes magnetic materials.

[0023] Mask 2 is a vapor deposition mask 2, and it is fabricated using semiconductor processes such as deposition, photolithography, and etching. This embodiment uses etching as an example to illustrate the fabrication of mask 2. For details on the fabrication of the patterned mask 2, please refer to [link to relevant documentation]. Figure 3 , Figure 3 for Figure 1 The schematic diagram shown illustrates the process of preparing a patterned mask in the fabrication method. The process of preparing patterned mask 2 includes the following: S111, Provides a mask material layer.

[0024] The mask material layer 22 is made of at least one of iron, cobalt, and nickel. By preparing the mask 2 with a metal material that has magnetic properties, the structural strength and durability of the mask 2 can be improved, making it less prone to damage during bonding and vapor deposition, and thus reusable. In addition, by providing a magnetic material, it is easier to achieve bonding through the magnetic backing plate 13.

[0025] S112, A patterned mask material layer is formed to form at least one first through-hole penetrating the mask material layer and a second through-hole surrounding the outer periphery of the first through-hole.

[0026] The mask material layer 22 is etched to form at least one first through-hole 23 and a second through-hole 24 penetrating the mask material layer 22. The second through-hole 24 surrounds the outer periphery of the first through-hole 23. The number of first through-holes 23 is consistent with the number of block protrusions 112 in the protrusions 11, and the shape of the first through-hole 23 is also adapted to the shape of the corresponding block protrusion 112. The shape of the second through-hole 24 is adapted to the shape of the corresponding annular protrusion 111.

[0027] S113. The remaining mask material layer after patterning serves as a mask plate. The mask plate includes a first part and a second part surrounding the outer periphery of the first part. A first through hole penetrates the first part, and a second through hole is disposed around the first part and between the second part.

[0028] See also Figure 4 , Figure 4 This is a top view of the photomask. The photomask 2 includes a first portion 25 and a second portion 26. The shape of the first portion 25 is adapted to the shape of the annular protrusion 111, such that the shape of the second through-hole 24, which is disposed between the first portion 25 and the second portion 26, is adapted to the shape of the annular protrusion 111. This ensures that the bonding material can be deposited on the annular protrusion 111 through the second through-hole 24 to form the bonding metal layer 12. In addition, the shape of the second portion 26 is adapted to the shape of the first wafer 1, and the second portion 26 can shield other areas of the first wafer 1 except for the protrusion 11, avoiding contamination of other areas during subsequent vapor deposition processes.

[0029] A connecting support structure 27 is formed between the first part 25 and the second part 26. The diameter of the connecting support structure 27 ranges from 80 nanometers to 100 nanometers. By setting the connecting support structure 27, the supporting force of the block protrusion 112 on the first part 25 can be used to support the second part 26 through the connecting support structure 27, preventing the second part 26 from contacting the wafer due to lack of support. This prevents process defects such as shading deviation or abnormal deposition of bonding material during the vapor deposition process. In addition, by setting the diameter of the connecting support structure 27 to between 80 nanometers and 100 nanometers, it is possible to avoid the connection support structure 27 being too large, which would affect the structure and shape of the bonding metal layer 12 formed by the vapor deposition process. It is also possible to avoid the connection support structure 27 being too small, which would result in insufficient support for the second part 26, thus ensuring the stability of the support for the second part 26.

[0030] It should be noted that the position of the connecting support structure 27 connecting the first part 25 and the second part 26 can be set according to the actual situation, and the number of connecting support structures 27 can also be set according to the actual situation. For example, in some embodiments, there are four connecting support structures 27, and one end of each connecting support structure 27 is connected to the corner of the first part 25, and the other end of the connecting support structure 27 is connected to the corresponding corner of the second part 26. By setting the connecting support structures 27 at the four corners, the support force for the second part 26 can be guaranteed, while minimizing the impact on the vapor deposition process.

[0031] S120. A first wafer is provided, the surface of the first wafer is provided with protrusions, and a magnetic backplate is provided on the side of the first wafer away from the protrusions.

[0032] The first wafer 1 can be any suitable material known to those skilled in the art, such as at least one of the following: silicon (Si), germanium (Ge), silicon germanium (SiGe), silicon carbide (SiC), silicon carbide (SiGeC), indium arsenide (InAs), gallium arsenide (GaAs), indium phosphide (InP), or other III / V compound semiconductors, including multilayer structures composed of these semiconductors, or silicon on insulator (SOI), silicon on insulator stacked (SSOI), silicon on insulator stacked (S-SiGeOI), silicon on insulator (SiGeOI), and germanium on insulator (GeOI), or it can also be a double-side polished wafer (DSP), or a ceramic substrate such as alumina, a quartz or glass substrate, etc.

[0033] At least one protrusion 11 may be provided on the surface of the first wafer 1, and each protrusion 11 is provided in the bonding region of the first wafer 1.

[0034] The protrusion 11 includes an annular protrusion 111 and a block protrusion 112 located inside the annular protrusion 111. The block protrusion 112 is the main bonding region.

[0035] The magnetic backplate 13 can completely cover the side of the first wafer 1 away from the protrusion 11, or it can be set only in a part of the target area of ​​the first wafer 1. At the same time, the thickness of the magnetic backplate 13 can also be set according to the actual situation, as long as it can be used to attract the mask 2 and achieve stable bonding between the mask 2 and the protrusion 11 structure.

[0036] S130. The mask is attached to the raised part of the surface by magnetic adsorption between the magnetic back plate and the mask.

[0037] The mask 2 is attached to the pre-defined portion of the protrusion 11 by magnetic adsorption between the magnetic back plate 13 and the mask 2. This allows for rapid fixation of the mask 2 without relying on complex mechanical positioning mechanisms or multi-step calibration processes.

[0038] The process of attaching the mask 2 to a portion of the surface of the protrusion 11 includes: attaching a first portion 25 to the side of the annular protrusion 111 near the block protrusion 112, so that the first through hole 23 corresponds to the block protrusion 112 and the second through hole 24 corresponds to the unattached portion of the annular protrusion 111. By attaching the first portion 25 to the side of the annular protrusion 111 near the block protrusion 112, that is, attaching the mask 2 to the inner side of the annular protrusion 111, the mask 2 can be supported by the annular protrusion 111, and the inner side of the annular protrusion 111 can be shielded by attaching the mask 2 to the inner side of the annular protrusion 111. This effectively reduces the risk of overflow and ensures performance.

[0039] In some embodiments, the contact length between the first portion 25 and the annular protrusion 111 is at least 10 μm, and the specific length can be set according to the actual situation, without any specific limitation here.

[0040] After the mask 2 is attached to a portion of the surface of the protrusion 11, the first through-hole 23 corresponds to the block protrusion 112, and the second through-hole 24 corresponds to the annular protrusion 111. In some embodiments, the orthographic projection of the first through-hole 23 coincides with the orthographic projection of the block protrusion 112 in a direction perpendicular to the first wafer 1. This arrangement allows the bonding material to be deposited on the top surface of the block protrusion 112 through the first through-hole 23 during the evaporation of the bonding material, effectively preventing the formation of bonding material residue on the sidewalls of the block protrusion 112.

[0041] In some other embodiments, in a direction perpendicular to the first wafer 1, the orthographic projection of the block protrusion 112 is located within the orthographic projection of the first through hole 23, that is, the outline range of the first through hole 23 is larger than the outline range of the block protrusion 112. Thus, during the evaporation of bonding material, the bonding material can not only be deposited on the top surface of the block protrusion 112 through the first through hole 23, but also completely encapsulate the sidewalls of the block protrusion 112. This results in the bonding area of ​​the bonding metal layer 12 generated on the block protrusion 112 being larger than the body area of ​​the block protrusion 112, thereby increasing the bonding contact area and increasing the bonding strength.

[0042] In some other embodiments, in a direction perpendicular to the first wafer 1, the edge of the second via 24 near the block protrusion 112 coincides with the edge of the annular protrusion 111 near the block protrusion 112. That is, during the deposition of bonding material, the bonding metal layer 12 formed after the bonding material passes through the second via 24 coincides with the edge of the annular protrusion 111 near the block protrusion 112, effectively preventing bonding material residue from forming on the sidewall of the annular protrusion 111.

[0043] In some other embodiments, the edge of the second through-hole 24 on the side away from the block protrusion 112 extends beyond the edge of the annular protrusion 111 on the side away from the block protrusion 112. That is, the outline of the second through-hole 24 is larger than the outline of the annular protrusion 111 on the side away from the block protrusion 112. Thus, during the vapor deposition of bonding material, the bonding material can not only be deposited on the top surface of the annular protrusion 111 through the second through-hole 24, but also completely encapsulate the sidewalls of the annular protrusion 111. This results in the bonding metal layer 12 formed on the annular protrusion 111 extending beyond the side of the annular protrusion 111 away from the block protrusion 112, thereby increasing the contact area of ​​the bonding and increasing the bonding strength.

[0044] In a direction perpendicular to the first wafer 1, the first wafer 1 has an alignment groove 14, and the mask 2 has an alignment hole 21 penetrating the mask 2. Before attaching the mask 2 to a portion of the surface of the protrusion 11, the fabrication method further includes: positioning the mask 2 and the protrusion 11 by using a laser to pass through the alignment hole 21 and the alignment groove 14. For example, a laser positioning device is activated to emit a laser beam, which penetrates the alignment hole 21 on the mask 2 in a direction perpendicular to the surface of the first wafer 1 and is directed into the alignment groove 14 of the first wafer 1. The reflected or transmitted laser signal is detected by a laser receiving component, and the deviation between the laser incident position and the alignment groove 14 is analyzed. Then, the mask 2 or the first wafer 1 is slightly adjusted until the deviation value fed back by the laser signal is within a preset range, thereby achieving alignment between the mask 2 and the protrusion 11 structure. Laser positioning eliminates the need for complex mechanical calibration fixtures or multiple manual adjustments. Real-time feedback of the laser signal allows for rapid alignment and calibration of the mask 2 and protrusion 11, significantly reducing positioning operation time. Furthermore, laser positioning is reusable, reducing costs.

[0045] S140. A bonding material is deposited on the raised area that is not bonded by the mask through a vapor deposition process to form a bonding metal layer.

[0046] In a vapor deposition process, the bonding material is heated and vaporized to form vapor deposition particles. These particles are then deposited on the protrusion 11 through the first through-hole 23 and the second through-hole 24 to form a bonding metal layer 12 that matches the first through-hole 23 and the second through-hole 24. Specifically, the surface of the mask 2 that is not attached to the protrusion 11 faces the vapor deposition source. The vapor deposition source heats and vaporizes the bonding material to form vapor deposition particles, which then pass sequentially through the first through-hole 23 and the second through-hole 24 to form the corresponding bonding metal layer 12 on the protrusion 11.

[0047] The bonding metal layer 12 is made of at least one of Ge, Al, Au, Cu, and Sn.

[0048] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A method for producing a bonded metal layer, characterized by, The preparation method comprises: preparing a patterned mask plate, a material of the mask plate comprising a magnetic material; providing a first wafer, a surface of the first wafer being provided with a protrusion, a side of the first wafer away from the protrusion being provided with a magnetic back plate; attaching the mask plate to a part of the surface of the protrusion through magnetic adsorption between the magnetic back plate and the mask plate; depositing a bonding material on an area of the protrusion not attached by the mask plate through an evaporation process to form a bonding metal layer.

2. The production method according to claim 1, characterized by, In a direction perpendicular to the first wafer, a positioning slot is provided on the first wafer, and a positioning hole penetrating through the mask plate is provided on the mask plate, and before the mask plate is attached to the part of the surface of the protrusion, the preparation method further comprises: positioning the mask plate and the protrusion through laser passing through the positioning hole and the positioning slot.

3. The preparation method according to claim 1, characterized in that, The preparation of the patterned mask plate comprises: providing a mask material layer; patterning the mask material layer to form at least one first through hole penetrating through the mask material layer and a second through hole surrounding an outer periphery of the first through hole; the remaining mask material layer after patterning serving as a mask plate, the mask plate comprising a first part and a second part surrounding an outer periphery of the first part, the first through hole penetrating through the first part, and the second through hole being arranged between the first part and the second part.

4. The production method according to claim 3, characterized by, The protrusion comprises a ring-shaped protrusion and a block-shaped protrusion inside the ring-shaped protrusion, and the attaching of the mask plate to the part of the surface of the protrusion comprises: attaching the first part to a side of the ring-shaped protrusion close to the block-shaped protrusion, so that the first through hole corresponds to the block-shaped protrusion, and the second through hole corresponds to a part of the ring-shaped protrusion not attached.

5. The preparation method according to claim 4, characterized in that, In a direction perpendicular to the first wafer, a projection of the first through hole coincides with a projection of the block-shaped protrusion, or the projection of the block-shaped protrusion is located within the projection of the first through hole.

6. The preparation method according to claim 3, characterized in that, The protrusion comprises a ring-shaped protrusion and a block-shaped protrusion inside the ring-shaped protrusion, and in a direction perpendicular to the first wafer, an edge of a side of the second through hole close to the block-shaped protrusion coincides with an edge of a side of the ring-shaped protrusion close to the block-shaped protrusion, and / or an edge of a side of the second through hole away from the block-shaped protrusion exceeds an edge of a side of the ring-shaped protrusion away from the block-shaped protrusion.

7. The production method according to any one of claims 3 to 6, characterized by, A connecting support structure is formed between the first part and the second part, and a diameter of the connecting support structure ranges from 80 nm to 100 nm.

8. The production method according to any one of claims 3 to 6, characterized by, The depositing of the bonding material on the area of the protrusion not attached by the mask plate through the evaporation process to form the bonding metal layer comprises: forming evaporation particles by heating and vaporizing the bonding material through the evaporation process, and depositing the evaporation particles on the protrusion through the first through hole and the second through hole to form the bonding metal layer matching the first through hole and the second through hole.

9. The production method according to any one of claims 1 to 6, characterized by, The material of the mask plate comprises at least one of iron, cobalt, and nickel.

10. The production method according to any one of claims 1 to 6, characterized by, The material of the bonding metal layer comprises at least one of Ge, Al, Au, Cu, and Sn.

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