Boron diffusion manufacturing process method
By preforming a sacrificial insulating dielectric film of silicon oxide on the surface of the silicon wafer, and forming a high-concentration boron silicon oxide insulating dielectric film in the boron deposition step, and then removing it by wet corrosion, the problem of silicon oxide being difficult to remove when high-concentration boron doped in the prior art is solved, the precipitation of boron is suppressed, and the stability of the process and the quality of the product are improved.
Patent Information
- Application Number
- CN202411961365.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-30
- Publication Date
- 2025-05-13
AI Technical Summary
When the existing boron diffusion process is doped at high concentrations, it is difficult to remove silicon oxide, resulting in drilling and corrosion problems and glue peeling in subsequent pattern processing, and boron precipitation is prone to occur, resulting in product abnormalities.
A layer of silicon oxide sacrificial insulating dielectric film is formed on the surface of the silicon wafer in advance. The high-concentration boron silicon oxide insulating dielectric film formed in the boron deposition step is formed on the surface layer thereon. These film layers are removed by wet corrosion to avoid the residue of silicon oxide and the precipitation of boron.
It effectively solves the problem that silicon oxide is difficult to remove when high concentration boron doped, inhibits boron precipitation, improves process stability and product quality, and is suitable for the manufacturing of semiconductor chips such as Schottky diodes and fast recovery diodes.
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Figure CN119993826A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of semiconductor technology, in particular to a boron diffusion manufacturing process method. Background Art
[0002] Semiconductor chips such as Schottky diodes (SBDs), fast recovery diodes (FRDs, or FREDs), rectifier diodes, and photovoltaic diodes must undergo a boron diffusion process during the processing to form a PN junction P-side doping with the required concentration and junction depth.
[0003] Conventional processes mainly adopt the following processing methods:
[0004] One method is to use ion implantation technology, which uses an ion implanter to sort and accelerate the required boron ions and implant them into silicon wafers. Although this method has high processing accuracy and good consistency, it requires an expensive ion implanter, and the equipment capacity for each processing is relatively limited, and the processing efficiency is relatively low.
[0005] Another method is to release the boron in a solid boron source or a gaseous boron source through a diffusion process at high temperature, and then diffuse the boron impurities into the silicon wafer at high temperature. This method has lower equipment investment, large processing capacity per time, and high efficiency. Generally, the boron diffusion processing method is to directly deposit boron after opening the boron diffusion window, and then perform boron push processing. This process method is prone to processing problems such as difficulty in removing silicon oxide when high-concentration boron is doped, especially for subsequent more delicate graphics processing, which will cause serious drilling problems and even glue shedding; in addition, after boron deposition, even after boron push, boron precipitation is prone to occur, resulting in product abnormalities. Summary of the invention
[0006] Technical issues solved
[0007] The purpose of the present invention is to make up for the deficiencies of the prior art and to provide a boron diffusion manufacturing process method that is not prone to forming difficult-to-etch silicon oxide and is not prone to boron precipitation.
[0008] Technical Solution
[0009] To achieve the above object, the present invention provides the following technical solution: A boron diffusion manufacturing process method, 1. comprising the following steps:
[0010] Step 1: Fabricate the required structure of the front layer on the lightly doped N-type substrate silicon, or first fabricate a lightly doped N-type epitaxial layer on the heavily doped N+ type substrate silicon, and then fabricate the required structure of the front layer on the N-type epitaxial layer;
[0011] Step 2: thermal oxidation growth or chemical vapor deposition of a blocking insulating dielectric film, wherein the blocking insulating dielectric film includes silicon oxide and silicon nitride;
[0012] Step 3: selectively removing the aforementioned blocking insulating dielectric film by wet etching or dry etching to form a boron diffusion window;
[0013] Step 4: forming a layer of sacrificial insulating dielectric film of silicon oxide on the surface of the silicon wafer by thermal oxidation growth or chemical vapor deposition;
[0014] Step 5: releasing boron from a solid boron source at high temperature, or decomposing boron from a boron-containing special gas, and introducing an auxiliary gas to deposit boron or a boron-containing substance on the surface of the silicon wafer, while further forming a layer of a silicon oxide insulating dielectric film containing a high concentration of boron on the surface of the silicon wafer, and the silicon oxide insulating dielectric film containing a high concentration of boron is formed on the upper surface of the silicon oxide sacrificial insulating dielectric film;
[0015] Step 6: removing the silicon oxide insulating dielectric film containing a high concentration of boron and at least a portion of the silicon oxide sacrificial insulating dielectric film pre-grown or deposited in step 4 by wet etching;
[0016] Step 7: Silicon wafer cleaning;
[0017] Step 8: Place the silicon wafer in a furnace tube with auxiliary gas, and perform boron push processing at high temperature to form the impurity concentration and junction depth distribution required for boron doping.
[0018] Preferably, in step 1, the resistivity of the lightly doped N-type substrate or the lightly doped N-type epitaxial layer is above 0.1Ω.cm, and the boron doping concentration is above 5x10 13 Atom / cm 3 above;
[0019] Preferably, in step 2, the thickness of the blocking insulating dielectric film is greater than 1000 Å.
[0020] Preferably, in step 4, the thickness of the sacrificial insulating dielectric film is 100-1000 Å.
[0021] Preferably, in step 5, the boron-containing special gas includes BF3, BCl3, BBr3, B2H6, or similar compound gases, the auxiliary gas includes O2 and N2, and the boron deposition temperature is 800-1100°C.
[0022] Preferably, in step 6, the silicon oxide insulating dielectric film is wet etched by HF or BOE solution, and the BOE solution is a mixture of HF acid and NH4F.
[0023] Preferably, in step 7, the cleaning is performed using an APM mixed solution, an HPM mixed solution, an SPM mixed solution, and dilute HF.
[0024] Preferably, in step 8, the auxiliary gas includes N2 and O2, and the boron pushing temperature is above 850°C.
[0025] Beneficial effects of the present invention:
[0026] The present invention proposes a boron diffusion manufacturing process method, in which a layer of silicon oxide sacrificial insulating dielectric film is pre-formed on the surface of a silicon wafer, and in the subsequent boron deposition step, a silicon oxide insulating dielectric film containing high concentration of boron is formed on the silicon oxide sacrificial insulating dielectric film, and finally the silicon oxide insulating dielectric film containing high concentration of boron on the sacrificial silicon oxide insulating dielectric film can be removed smoothly by wet etching. The problem that the silicon oxide insulating dielectric film containing high concentration of boron is difficult to remove in the prior art is solved, and the precipitation of high concentration of boron can also be suppressed, and the method can be widely used in the manufacture of power semiconductor chips and photovoltaic diodes such as Schottky diodes, fast recovery diodes, and rectifier diodes. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 It is a schematic diagram of the overall steps of the present invention. DETAILED DESCRIPTION
[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0029] like Figure 1 As shown, the present invention proposes a boron diffusion manufacturing process method, 1. comprising the following steps:
[0030] Step 1: Fabricate the required structure of the front layer on the lightly doped N-type substrate silicon, or first fabricate a lightly doped N-type epitaxial layer on the heavily doped N+-type substrate silicon, and then fabricate the required structure of the front layer on the N-type epitaxial layer; in step 1, the resistivity of the lightly doped N-type substrate or the lightly doped N-type epitaxial layer is above 0.1Ω.cm, and the boron doping concentration is 5x10 13 Atom / cm 3 above.
[0031] Step 2: thermal oxidation growth or chemical vapor deposition of a blocking insulating dielectric film, wherein the blocking insulating dielectric film comprises silicon oxide and silicon nitride; in step 2, the thickness of the blocking insulating dielectric film is above 1000 Å.
[0032] Step 3: selectively removing the aforementioned blocking insulating dielectric film by wet etching or dry etching to form a boron diffusion window;
[0033] Step 4: forming a layer of sacrificial insulating dielectric film of silicon oxide on the surface of the silicon wafer by thermal oxidation growth or chemical vapor deposition; in step 4, the thickness of the sacrificial insulating dielectric film is 100-1000A.
[0034] Step 5: Release boron from the solid boron source at high temperature, or decompose boron from the boron-containing special gas, and introduce auxiliary gas to deposit boron or boron-containing substances on the surface of the silicon wafer, and further form a layer of silicon oxide insulating dielectric film containing high concentration of boron on the surface of the silicon wafer, and the silicon oxide insulating dielectric film containing high concentration of boron is formed at a local position of the silicon oxide sacrificial insulating dielectric film; in step 5, the boron-containing special gas includes BF3, BC13, BBr3, B2H6, or similar compound gas, the auxiliary gas includes O2 and N2, and the boron deposition temperature is 800-1100℃.
[0035] Step 6: Remove the silicon oxide insulating dielectric film containing a high concentration of boron and at least part of the silicon oxide sacrificial insulating dielectric film pre-grown or deposited in step 4 by wet etching; in step 6, the silicon oxide insulating dielectric film is wet etched by HF or BOE liquid, and the BOE liquid is a mixture of HF acid and NH4F.
[0036] Step 7: silicon wafer cleaning; in step 7, APM mixed solution, HPM mixed solution, SPM mixed solution and dilute HF are used for cleaning.
[0037] Step 8: Place the silicon wafer in a furnace tube with auxiliary gas, and perform boron push processing at high temperature to form the impurity concentration and junction depth distribution required for boron doping. The auxiliary gas in step 8 includes N2 and O2, and the boron push temperature is above 850℃.
[0038] The boron diffusion manufacturing process proposed in this embodiment forms a layer of silicon oxide sacrificial insulating dielectric film on the silicon wafer before boron deposition, so that the silicon oxide insulating dielectric film containing high concentration of boron formed in the subsequent steps is formed on the upper surface of the silicon oxide sacrificial insulating dielectric film, and finally removes at least part of the silicon oxide sacrificial insulating dielectric film and all the silicon oxide insulating dielectric films containing high concentration of boron thereon by wet etching. Or remove all the silicon oxide sacrificial insulating dielectric films and all the silicon oxide insulating dielectric films containing high concentration of boron. The difficulty is much less than the difficulty of removing the silicon oxide insulating dielectric film containing high concentration of boron formed by boron deposition in the conventional process after boron advancement. Therefore, the problem of difficulty in removing silicon oxide generated during high concentration boron doping in the prior art is solved, especially when pattern doping is performed.
[0039] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.
Claims
1. A boron diffusion manufacturing process, characterized in that: The steps include: Step 1: Fabricate the required structure of the front layer on the lightly doped N-type substrate silicon, or first fabricate a lightly doped N-type epitaxial layer on the heavily doped N+ type substrate silicon, and then fabricate the required structure of the front layer on the N-type epitaxial layer; Step 2: thermal oxidation growth or chemical vapor deposition of a blocking insulating dielectric film, wherein the blocking insulating dielectric film includes silicon oxide and silicon nitride; Step 3: selectively removing the aforementioned blocking insulating dielectric film by wet etching or dry etching to form a boron diffusion window; Step 4: forming a layer of sacrificial insulating dielectric film of silicon oxide on the surface of the silicon wafer by thermal oxidation growth or chemical vapor deposition; Step 5: releasing boron from a solid boron source at high temperature, or decomposing boron from a boron-containing special gas, and introducing an auxiliary gas to deposit boron or a boron-containing substance on the surface of the silicon wafer, while further forming a layer of a silicon oxide insulating dielectric film containing a high concentration of boron on the surface of the silicon wafer, and the silicon oxide insulating dielectric film containing a high concentration of boron is formed on the upper surface of the silicon oxide sacrificial insulating dielectric film; Step 6: removing the silicon oxide insulating dielectric film containing a high concentration of boron and at least a portion of the silicon oxide sacrificial insulating dielectric film pre-grown or deposited in step 4 by wet etching; Step 7: Silicon wafer cleaning; Step 8: Place the silicon wafer in a furnace tube with auxiliary gas, and perform boron driving processing at high temperature to form the impurity concentration and junction depth distribution required for boron doping.
2. A boron diffusion manufacturing process according to claim 1, characterized in that: In step 1, the resistivity of the lightly doped N-type substrate or the lightly doped N-type epitaxial layer is above 0.1Ω.cm, and the boron doping concentration is 5x10 13 Atom / cm 3 above.
3. The boron diffusion manufacturing process according to claim 1, characterized in that: In step 2, the thickness of the blocking insulating dielectric film is above 1000A.
4. The boron diffusion manufacturing process according to claim 1, characterized in that: In step 4, the thickness of the sacrificial insulating dielectric film is 100-1000A.
5. The boron diffusion manufacturing process according to claim 1, characterized in that: In step 5, the boron-containing special gas includes BF3, BCl3, BBr3, B2H6, the auxiliary gas includes O2 and N2, and the boron deposition temperature is 800-1100℃.
6. The boron diffusion manufacturing process according to claim 1, characterized in that: In step 6, the silicon oxide insulating dielectric film is wet etched by HF or BOE solution, where the BOE solution is a mixture of HF acid and NH4F.
7. The boron diffusion manufacturing process according to claim 1, characterized in that: In step 7, the cleaning is performed using APM mixed solution, HPM mixed solution, SPM mixed solution and dilute HF.
8. The boron diffusion manufacturing process according to claim 1, characterized in that: In step 8, the auxiliary gas includes N2 and O2, and the boron advancement temperature is above 850°C.