Preparation method of polycrystalline silicon thin film with uniformly distributed stress
By detecting the stress distribution and injecting materials such as phosphorus or boron on the surface of the polycrystalline silicon film, the problem of uneven stress distribution of the film is solved, and the performance consistency and high yield of MEMS products are achieved.
Patent Information
- Application Number
- CN202411413002.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-11
- Publication Date
- 2025-01-10
AI Technical Summary
In semiconductor manufacturing, uneven stress distribution of polysilicon thin films leads to inconsistent performance of MEMS products, making it difficult to achieve high yield and consistent performance in large-scale mass production.
By detecting the stress distribution of the polycrystalline silicon film, injecting materials such as phosphorus or boron on the surface of the film according to the stress distribution, adjusting the stress distribution, and using ion implantation technology to implant set materials in a predetermined area, and annealing is performed.
The uniform stress distribution of polysilicon thin film is achieved, and the performance consistency of MEMS products and the yield of large-scale mass production are improved.
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Figure CN119287507A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of semiconductor manufacturing technology, and in particular, to a method for preparing a polysilicon film with uniformly distributed stress. Background Art
[0002] In the semiconductor field, polysilicon with certain stress is often used, such as MEMS microphones, MEMS speakers, MEMS oscillators and other products. In these products, polysilicon is often used as a vibrating element. The polysilicon film is stimulated to vibrate by external signals, so as to detect the capacitance of the entire structure to achieve the function of detecting sound, vibration, etc. Therefore, the preparation of polysilicon film with excellent performance is very important in the application of the above products. With the development of semiconductor integrated circuits, the preparation of polysilicon film has become a common technical means. However, in the process of large-scale mass production, how to achieve high yield and achieve the same polysilicon at different positions on the same wafer is a technical problem.
[0003] The existing polysilicon preparation technology usually has a large number of steps, the first is thin film deposition, the second is annealing, and the most commonly used equipment in the thin film deposition process is LPCVD (low pressure vapor deposition). LPCVD is a technology that deposits thin films on the surface of a substrate through chemical reactions at relatively low pressures. The gas source for preparing polysilicon is mostly silane or dichlorosilane, and polysilicon is generated by the cracking of silane or dichlorosilane at high temperatures. Usually, the polysilicon film we prepare needs to be conductive, so it is necessary to dope phosphorus or boron during the growth process to achieve the preparation of conductive polysilicon film. The preparation gases for phosphorus or boron are phosphine and borane. Therefore, when growing doped polysilicon, gases such as silane and phosphine (borane) need to be passed through the equipment.
[0004] Since LPCVD is a furnace-tube type device that can deposit multiple wafers at a time, the wafers are stuck in the slots of a quartz or SiC wafer boat horizontally or vertically during growth. For many devices, the gas is blown from the edge of the wafer boat parallel to the wafer surface. Although the wafer is constantly rotating during the growth process, the temperature field is not evenly distributed, and the temperature at the edge of the wafer is higher. The stress of the grown polysilicon is always smaller, and it is difficult to achieve very uniform stress on the same wafer. Because the stress of the polysilicon film is closely related to the performance of the final MEMS product, if the polysilicon stress is inconsistent at different locations on the wafer, it is difficult to prepare high-yield, consistent performance related MEMS chips. Summary of the invention
[0005] The purpose of the present application is to provide a method for preparing a polycrystalline silicon film with uniformly distributed stress. Some polycrystalline silicon films contain phosphorus or boron, and the higher the phosphorus or boron doping concentration, the smaller the stress under the same conditions. Therefore, the present application injects a set material on the surface of the polycrystalline silicon film according to the stress distribution. The set material can be phosphorus or boron, or it can also be other materials that can affect stress, so as to solve the problem of uneven stress distribution of polycrystalline silicon films in the prior art.
[0006] Other features and advantages of the present application will become apparent from the following detailed description, or may be learned in part by the practice of the present application.
[0007] According to one aspect of an embodiment of the present application, a method for preparing a polycrystalline silicon film with uniformly distributed stress is provided, the method comprising: providing a substrate, depositing a polycrystalline silicon film on the surface of the substrate using an LPCVD process; detecting and obtaining the stress distribution of the polycrystalline silicon film; injecting a set material into the surface of the polycrystalline silicon film according to the stress distribution, the material of the polycrystalline silicon film containing the set material; and annealing the polycrystalline silicon film through an annealing process.
[0008] In some embodiments, in injecting a set material into the surface of the polysilicon film according to the stress distribution, the method includes: calculating a preset amount of the set material to be injected according to the stress distribution; calculating a predetermined area to be injected with the set material according to the stress distribution; sending the substrate into an ion implanter; and injecting a preset amount of the set material into a predetermined area of the polysilicon film.
[0009] In some embodiments, after calculating the predetermined area where the set material needs to be injected based on the stress distribution, the method further includes: coating a photoresist on the polysilicon film; exposing the photoresist according to the shape and size of the predetermined area; and developing the exposed portion of the photoresist to obtain a predetermined area exposing the polysilicon film.
[0010] In some embodiments, after a preset amount of a setting material is implanted into a predetermined region of the polysilicon film, the method further comprises: removing the photoresist and cleaning the polysilicon film.
[0011] In some embodiments, the substrate has a temperature resistance range of above 900°C.
[0012] In some embodiments, in the providing of the substrate, the method includes: providing a polycrystalline silicon wafer with silicon oxide or silicon nitride attached to the surface as the substrate.
[0013] In some embodiments, the polysilicon film is doped with phosphorus or boron, and the set material is phosphorus or boron.
[0014] In some embodiments, the energy range of ion implantation by the implanter is 10 KeV to 200 KeV.
[0015] In some embodiments, the ion implantation dose range of the implanter is 1e13 / cm 2 ~1e15 / cm 2 .
[0016] In some embodiments, the polysilicon film has a thickness ranging from 100 nm to 2 μm.
[0017] The technical solution of the present application has a significant beneficial effect compared with the prior art: since LPCVD is a furnace tube type device, multiple wafers can be deposited at one time, so when growing, the wafers are stuck in the slots of a quartz or SiC wafer boat horizontally or vertically. For many devices, the gas is blown from the edge of the wafer boat parallel to the surface of the wafer. Although the wafer is constantly rotating during the growth process, the temperature at the edge of the wafer is higher due to the uneven distribution of the temperature field, and the stress of the grown polysilicon is always smaller. Some polysilicon films contain phosphorus or boron, and because research has found that for polysilicon films, if it is a phosphorus-doped polysilicon film, the higher the phosphorus doping concentration, the smaller the stress under the same conditions; if it is a boron-doped polysilicon film, the higher the boron doping concentration, the smaller the stress under the same conditions. Therefore, the present application injects phosphorus or boron on the surface of the polysilicon film according to the stress distribution to solve the problem of uneven stress distribution of polysilicon films in the prior art. In other embodiments, other materials that can affect stress can also be injected. The method of the present application can produce polycrystalline silicon thin films with good uniformity, and can improve the yield and chip consistency during large-scale mass production.
[0018] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The above and other features and advantages of the present application will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings.
[0020] Figure 1 A flowchart according to an embodiment of the present application is shown.
[0021] Figure 2 A schematic structural diagram of a polysilicon film and a predetermined area thereof according to an embodiment of the present application is shown.
[0022] The reference numerals are explained as follows: 1. polysilicon thin film; 2. annular photoresist. DETAILED DESCRIPTION
[0023] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this application will be more comprehensive and complete and fully convey the concept of the example embodiments to those skilled in the art.
[0024] In addition, described feature, structure or characteristic can be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present application. However, those skilled in the art will appreciate that the technical scheme of the present application can be put into practice without one or more of the specific details, or other methods, components, devices, steps, etc. can be adopted. In other cases, known methods, devices, realizations or operations are not shown or described in detail to avoid blurring the various aspects of the application.
[0025] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities may be implemented in software form, or in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.
[0026] The flowcharts shown in the accompanying drawings are only exemplary and do not necessarily include all the contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps can be decomposed, and some operations / steps can be combined or partially combined, so the actual execution order may change according to actual conditions.
[0027] The technical solution of the embodiment of the present application is briefly described below:
[0028] According to some embodiments, Figure 1 As shown, the present application provides a method for preparing a polycrystalline silicon film with uniformly distributed stress, the method comprising:
[0029] Step 100, providing a substrate, and depositing a polysilicon film 1 on the surface of the substrate by using an LPCVD process;
[0030] Step 200, detecting and obtaining the stress distribution of the polysilicon film 1;
[0031] Step 300, injecting a set material into the surface of the polysilicon film 1 according to the stress distribution, wherein the material of the polysilicon film 1 contains the set material;
[0032] Step 400 , annealing the polysilicon film 1 through an annealing process.
[0033] Some polycrystalline silicon films 1 contain phosphorus or boron, and the higher the phosphorus or boron doping concentration, the smaller the stress under the same conditions. Therefore, the present application injects a set material into the surface of the polycrystalline silicon film 1 according to the stress distribution. The set material can be phosphorus or boron, or it can also be other materials that can affect stress, so as to solve the problem of uneven stress distribution of the polycrystalline silicon film 1 in the prior art.
[0034] In order to make those skilled in the art better understand the present application, Figure 1 The details of this application are explained in detail.
[0035] According to some embodiments, in step 300, a setting material is injected into the surface of the polysilicon film 1 according to the stress distribution, and the method specifically includes:
[0036] Step 310, calculating a preset amount of a set material to be injected according to the stress distribution.
[0037] Specifically, in step 310 , a preset amount is calculated according to the stress distribution, and the preset amount is the amount of a preset material that needs to be injected into the surface of the polysilicon film 1 .
[0038] Step 320, calculating the predetermined area where the set material needs to be injected according to the stress distribution.
[0039] Specifically, in step 320 , a predetermined area is calculated according to the stress distribution, and the predetermined area is an area where a set material needs to be injected into the surface of the polysilicon film 1 .
[0040] Step 330, sending the substrate into an ion implanter.
[0041] Step 340 , injecting a preset amount of a setting material into a predetermined area of the polysilicon film 1 .
[0042] Specifically, the energy range of ion implantation by the implanter is usually 10KeV to 200KeV, and the dose range of ion implantation is usually 1e13 / cm 2 to 1e15 / cm 2 .
[0043] Furthermore, in step 320, after calculating the predetermined area to be injected with the set material according to the stress distribution, the method further includes:
[0044] Step 321, coating photoresist on the polysilicon film 1;
[0045] Step 322, exposing the photoresist according to the shape and size of the predetermined area;
[0046] Step 323 , developing the exposed portion of the photoresist to obtain a predetermined area exposing the polysilicon film 1 and the patterned photoresist.
[0047] In some specific embodiments, Figure 2 As shown, the substrate and the polysilicon film 1 are circular, and the exposed portion of the photoresist is developed to obtain a ring-shaped photoresist 2 covering the edge of the polysilicon film 1 .
[0048] According to some embodiments, after step 340, a preset amount of a setting material is injected into a predetermined area of the polysilicon film 1, the method further comprises:
[0049] Step 341 , removing the photoresist and cleaning the polysilicon film 1 .
[0050] In some embodiments, the substrate is made of polysilicon wafer, or other materials. The temperature resistance range of the substrate must be at least above 900°C.
[0051] In step 100, a substrate is provided, wherein the method includes:
[0052] A polycrystalline silicon wafer with silicon oxide or silicon nitride attached to the surface is provided as a substrate.
[0053] In some embodiments, phosphorus or boron is doped into the polysilicon film 1 , and the material is set to be phosphorus or boron.
[0054] In some specific embodiments, the thickness of the polysilicon film 1 is in the range of 100 nm-2 μm.
[0055] Since LPCVD is a furnace tube type device, multiple wafers can be deposited at one time. Therefore, when growing, the wafers are stuck in the slots of a quartz or SiC wafer boat horizontally or vertically. For many devices, the gas is blown from the edge of the wafer boat parallel to the surface of the wafer. Although the wafer is constantly rotating during the growth process, the temperature at the edge of the wafer is higher due to the uneven distribution of the temperature field, and the stress of the grown polysilicon is always smaller. Some polysilicon films 1 contain phosphorus or boron, and because research has found that for polysilicon films 1, if it is a phosphorus-doped polysilicon film 1, the higher the phosphorus doping concentration, the smaller the stress under the same conditions; if it is a boron-doped polysilicon film 1, the higher the boron doping concentration, the smaller the stress under the same conditions. Therefore, the present application injects phosphorus or boron on the surface of the polysilicon film 1 according to the stress distribution to solve the problem of uneven stress distribution of the polysilicon film 1 in the prior art. In other embodiments, other materials that can affect stress can also be injected. The method of the present application can produce a polysilicon film 1 with good uniformity, and can improve the yield and chip consistency during large-scale mass production.
[0056] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the embodiments disclosed herein. The present application is intended to cover any variations, uses or adaptations of the present application, which follow the general principles of the present application and include common knowledge or customary technical means in the art that are not disclosed in the present application.
[0057] It should be understood that the present application is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.
Claims
1. A method for preparing a polycrystalline silicon film with uniformly distributed stress, characterized in that: The method comprises: Providing a substrate, and depositing a polycrystalline silicon thin film on the surface of the substrate by using an LPCVD process; Detecting and obtaining stress distribution of the polysilicon film; Injecting a setting material into the surface of the polysilicon film according to the stress distribution, wherein the material of the polysilicon film contains the setting material; The polysilicon film is annealed through an annealing process.
2. The method according to claim 1, characterized in that Injecting a setting material into the surface of the polysilicon film according to the stress distribution, the method comprises: Calculating a preset amount of the set material to be injected according to the stress distribution; Calculating a predetermined area where the set material needs to be injected according to the stress distribution; feeding the substrate into an ion implanter; A preset amount of a setting material is implanted into a predetermined area of the polysilicon film.
3. The method according to claim 2, characterized in that After calculating the predetermined area to be injected with the set material according to the stress distribution, the method further includes: coating a photoresist on the polysilicon film; Exposing the photoresist according to the shape and size of the predetermined area; The exposed portion of the photoresist is developed to obtain a predetermined area where the polysilicon film is exposed.
4. The method according to claim 3, characterized in that After injecting a preset amount of setting material into a predetermined area of the polysilicon film, the method further includes: The photoresist is removed, and the polysilicon film is cleaned.
5. The method according to claim 1, characterized in that The temperature resistance range of the substrate is above 900°C.
6. The method according to claim 1, characterized in that In the providing of the substrate, the method comprises: A polycrystalline silicon wafer with silicon oxide or silicon nitride attached to the surface is provided as a substrate.
7. The method according to claim 1, characterized in that The polysilicon film is doped with phosphorus or boron, and the setting material is phosphorus or boron.
8. The method according to claim 2, characterized in that: The energy range of ion implantation of the implanter is 10KeV to 200KeV.
9. The method according to claim 8, characterized in that The ion implantation dose range of the implanter is 1e13 / cm 2 ~1e15 / cm 2 .
10. The method according to claim 1, characterized in that The thickness of the polysilicon film ranges from 100 nm to 2 μm.