Silicon-based product and oxidation process thereof
Through the oxidation process of silicon-based products using different gases for oxidation treatment in three stages, the problems of minority life and fragmentation rate in high-temperature long-term processes are solved, and shorter oxidation time and lower fragmentation rate are achieved.
Patent Information
- Application Number
- CN202411591244.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-08
- Publication Date
- 2025-02-25
AI Technical Summary
The existing high-temperature long-term manufacturing process cannot take into account the low-slave lifespan and fragmentation rate of silicon-based products.
Three-stage oxidation process is adopted: ozone is introduced in the initial oxidation stage, water and oxygen are introduced in the second oxidation stage, and oxygen and hydrogen are introduced in the third oxidation stage to shorten the oxidation time and repair lattice distortion.
Effectively shortens the oxidation time, reduces the fragmentation rate, and extends the nucleus life of silicon-based products.
Smart Images
Figure CN119521829A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of silicon-based product oxidation, and in particular to a silicon-based product and an oxidation process thereof. Background Art
[0002] TOPCon solar cells are the mainstream product of crystalline silicon solar cells at present or for a long time in the future; the boron diffusion process is an indispensable part of the TOPCon cell manufacturing process and is the physical basis for forming PN junctions and separating carriers.
[0003] At present, the mainstream boron diffusion oxidation process in the industry is the dry oxygen process. That is, oxygen (O2) is introduced during the entire oxidation process. This method and process usually requires processing at a high oxidation temperature of ≥1030℃ and a long oxidation time of ≥1h to ensure that the prepared oxide layer is uniform and dense, so as to obtain a higher minority carrier lifetime.
[0004] However, the high oxidation temperature and long oxidation time of the dry oxygen process will lead to negative effects such as increased hidden cracks in the battery cells and shortened life of quartz devices. Therefore, automated loading and unloading during the preparation process will result in a high fragmentation rate. Summary of the invention
[0005] In view of this, the present invention provides a silicon-based product and an oxidation process thereof to solve the problem that the existing high-temperature and long-time process cannot take into account both the minority carrier lifetime and the fragmentation rate.
[0006] In a first aspect, the present invention provides an oxidation process for a silicon-based product, comprising:
[0007] In the initial oxidation stage, ozone is introduced during the heating process for treatment;
[0008] In the second oxidation stage, water and oxygen are introduced for treatment at the early stage of constant temperature oxidation;
[0009] In the third step, oxidation, oxygen and hydrogen are introduced for treatment at the end of constant temperature oxidation.
[0010] Beneficial effects: The present invention first performs ozone oxidation, and ozone has a higher oxidizing property than oxygen. This method can allow the surface of the silicon-based product to begin to quickly grow an oxide layer (SiO2) at a relatively low temperature (i.e., under the temperature conditions during the heating process). The present invention then performs wet oxygen oxidation, and wet oxygen has a faster oxidation rate, so it can simultaneously reduce the process temperature and shorten the process time, thereby alleviating problems such as hidden cracks caused by high-temperature processes and reducing the fragmentation rate of silicon-based products. The present invention finally introduces oxygen and hydrogen in the later stage of constant temperature oxidation. Since the Si / SiO2 interface gradually moves toward the inside of the silicon wafer, the dry oxygen (O2) introduced in the later stage of constant temperature oxidation can grow a denser oxide layer at the Si / SiO2 interface, protecting the inside of the silicon wafer while reducing the possibility of pollution caused by H2O in the early stage of constant temperature oxidation; at the same time, the introduction of hydrogen can accelerate the diffusion of doped atoms to SiO2, making it easier to meet the high square resistance process requirements, and hydrogen can provide body passivation and surface passivation for silicon-based products, repair the lattice distortion in the body of silicon-based products, and alleviate the problem of reduced minority carrier lifetime caused by high-temperature processes. Therefore, the present invention uses different gases for oxidation treatment in three stages, which can effectively shorten the process time required for oxidation and repair the lattice distortion in the silicon-based product, thereby achieving the effect of simultaneously reducing the fragmentation rate and extending the minority carrier lifetime of the silicon-based product.
[0011] In an optional embodiment, the temperature of the isothermal oxidation is 1000-1050°C.
[0012] In an optional embodiment, the treatment time of the initial oxidation stage is 500-2000s;
[0013] And / or, the gas flow rate in the initial oxidation stage is 3000-30000 sccm, wherein the content of ozone is 50-100%.
[0014] The treatment time of the second oxidation stage is 1000-5000s;
[0015] And / or, in the second oxidation stage, the gas flow rate is 5000-50000 sccm, wherein the water content accounts for 1%-50%.
[0016] The treatment time of the third oxidation stage is 500-2000s;
[0017] And / or, in the third oxidation stage, the gas flow rate is 3000-30000 sccm, wherein the content of hydrogen is ≤20%.
[0018] Beneficial effect: The present invention can generate an oxide layer in a shorter time, further shorten the oxidation time, and reduce the fragmentation rate.
[0019] The oxidation process is carried out under a protective atmosphere.
[0020] In an optional embodiment, the protective atmosphere comprises nitrogen.
[0021] In a second aspect, the present invention further provides an oxide layer prepared by the above process.
[0022] At the same time, the present invention also provides a silicon-based product having the above-mentioned oxide layer thereon.
[0023] In an optional embodiment, the silicon-based product is a solar cell, preferably a TOPCon cell. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0025] Figure 1 This is a process flow chart of Example 1 of the present invention.
[0026] Figure 2 This is a process flow chart of Example 2 of the present invention. DETAILED DESCRIPTION
[0027] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are 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 those skilled in the art without creative work are within the scope of protection of the present invention.
[0028] Example 1
[0029] A boron diffusion and oxidation process for silicon-based products, such as Figure 1 As shown, including:
[0030] 1. Enter the boat, place the silicon wafer to be diffused and oxidized by boron on the silicon nitride paddle, and place it in the quartz tube by the boat pushing mechanism.
[0031] 2. Evacuate the furnace, reduce the gas pressure in the furnace tube and raise the temperature to 800℃.
[0032] 3. Leak detection: Check the tightness of the furnace tube.
[0033] 4. Temperature-rising source deposition: At 850°C, N2 / O2 / BCl3 were introduced for deposition diffusion. The deposition diffusion time was 500s, the gas flow rate was 4000sccm, the N2 content accounted for 60%, the O2 content accounted for 30%, and the BCl3 content accounted for 10%.
[0034] 5. Pushing: At 950°C, nitrogen is introduced for pushing, and the pushing time is 600s.
[0035] 6. Temperature oxidation: The temperature is raised to 1030°C, and ozone and nitrogen are introduced throughout the process for 1000s of preliminary oxidation. The gas flow rate is 10000sccm, the ozone content accounts for 90%, and the rest is nitrogen.
[0036] 7. Preliminary stage of constant temperature oxidation: At 1030°C, nitrogen, oxygen and water are introduced for 2500s of the second step of oxidation, with a gas flow rate of 30000sccm, an oxygen content of 65%, a water content of 30%, and the rest being nitrogen.
[0037] 8. Late stage of constant temperature oxidation: At 1030°C, nitrogen, oxygen and hydrogen are introduced for 1000s of the third step of oxidation, with a gas flow rate of 10000sccm, an oxygen content of 90%, a hydrogen content of 5%, and the rest being nitrogen.
[0038] 9. Cooling: Only nitrogen is introduced and the temperature drops to 850°C.
[0039] 10. Exiting the boat: Break the vacuum, and the silicon nitride paddle will bring the silicon wafers that have been diffused by boron and oxidized out of the furnace tube.
[0040] Example 2
[0041] An oxidation process for silicon-based products, such as Figure 2 As shown, including:
[0042] 1. Enter the boat, place the silicon wafer to be oxidized on the silicon nitride paddle, and place it in the quartz tube by the boat pusher mechanism.
[0043] 2. Evacuate the furnace, reduce the gas pressure in the furnace tube and raise the temperature to 800℃.
[0044] 3. Leak detection: Check the tightness of the furnace tube.
[0045] 4. Temperature oxidation: The temperature is raised to 1030°C, and ozone and nitrogen are introduced throughout the process for 1000s of preliminary oxidation. The gas flow rate is 10000sccm, of which the ozone content accounts for 90% and the rest is nitrogen.
[0046] 5. Preliminary stage of constant temperature oxidation: At 1030°C, nitrogen, oxygen and water are introduced for 2500s of the second step of oxidation, with a gas flow rate of 30000sccm, of which the oxygen content accounts for 65%, the water content accounts for 30%, and the rest is nitrogen.
[0047] 6. Late stage of constant temperature oxidation: At 1030°C, nitrogen, oxygen and hydrogen are introduced for 1000s of the third step of oxidation with a gas flow rate of 10000sccm, of which the oxygen content accounts for 90%, the hydrogen content accounts for 5%, and the rest is nitrogen.
[0048] 7. Cooling: Only nitrogen is introduced and the temperature drops to 850°C.
[0049] 8. Exiting the boat: Break the vacuum, and the silicon nitride paddle will bring the oxidized silicon wafers out of the furnace tube.
[0050] Example 3
[0051] An oxidation process for a silicon-based product, comprising:
[0052] 1. Enter the boat, place the silicon wafer to be oxidized on the silicon nitride paddle, and place it in the quartz tube by the boat pusher mechanism.
[0053] 2. Evacuate the furnace, reduce the gas pressure in the furnace tube and raise the temperature to 800℃.
[0054] 3. Leak detection: Check the tightness of the furnace tube.
[0055] 4. Temperature-raising oxidation: The temperature is raised to 1050°C, and ozone is introduced throughout the process for 2000s of preliminary oxidation. The gas flow rate is 30000sccm, and the ozone content accounts for 100%.
[0056] 5. Preliminary stage of constant temperature oxidation: At 1050°C, oxygen and water are introduced for 5000s of second step oxidation, with a gas flow rate of 50000sccm, in which the oxygen content accounts for 50% and the water content accounts for 50%.
[0057] 6. Late stage of constant temperature oxidation: At 1050°C, oxygen and hydrogen are introduced for 2000s of the third step of oxidation with a gas flow rate of 30000sccm, in which the oxygen content accounts for 80% and the hydrogen content accounts for 20%.
[0058] 7. Cooling: Only nitrogen is introduced and the temperature drops to 850°C.
[0059] 8. Exiting the boat: Break the vacuum, and the silicon nitride paddle will bring the oxidized silicon wafers out of the furnace tube.
[0060] Example 4
[0061] An oxidation process for a silicon-based product, comprising:
[0062] 1. Enter the boat, place the silicon wafer to be oxidized on the silicon nitride paddle, and place it in the quartz tube by the boat pusher mechanism.
[0063] 2. Evacuate the furnace, reduce the gas pressure in the furnace tube and raise the temperature to 800℃.
[0064] 3. Leak detection: Check the tightness of the furnace tube.
[0065] 4. Temperature oxidation: The temperature is raised to 1000°C, and ozone and nitrogen are introduced throughout the process for 500s of initial oxidation. The gas flow rate is 3000sccm, of which the ozone content accounts for 50% and the rest is nitrogen.
[0066] 5. Preliminary stage of constant temperature oxidation: At 1000°C, oxygen and water are introduced for 1000s of second step oxidation, with a gas flow rate of 5000sccm, in which the oxygen content accounts for 99% and the water content accounts for 1%.
[0067] 6. Late stage of constant temperature oxidation: At 1000°C, oxygen and hydrogen are introduced for 500s of the third step of oxidation, with a gas flow rate of 3000sccm, in which the oxygen content accounts for 99% and the hydrogen content accounts for 1%.
[0068] 7. Cooling: Only nitrogen is introduced and the temperature drops to 850°C.
[0069] 8. Exiting the boat: Break the vacuum, and the silicon nitride paddle will bring the oxidized silicon wafers out of the furnace tube.
[0070] Comparative Example 1
[0071] An oxidation process for a silicon-based product, comprising:
[0072] 1. Enter the boat, place the silicon wafer to be oxidized on the silicon nitride paddle, and place it in the quartz tube by the boat pusher mechanism.
[0073] 2. Evacuate the furnace, reduce the gas pressure in the furnace tube and raise the temperature to 800℃.
[0074] 3. Leak detection: Check the tightness of the furnace tube.
[0075] 4. Oxidation: Raise the temperature to 1050°C, introduce oxygen, and perform oxidation for 12500s. The gas flow rate is 30000sccm, and the oxygen content is 100%.
[0076] 5. Cooling: Only nitrogen is introduced and the temperature drops to 850°C.
[0077] 6. Exiting the boat: Break the vacuum, and the silicon nitride paddle will bring the oxidized silicon wafers out of the furnace tube.
[0078] Comparative Example 2
[0079] An oxidation process for a silicon-based product, comprising:
[0080] 1. Enter the boat, place the silicon wafer to be oxidized on the silicon nitride paddle, and place it in the quartz tube by the boat pusher mechanism.
[0081] 2. Evacuate the furnace, reduce the gas pressure in the furnace tube and raise the temperature to 800℃.
[0082] 3. Leak detection: Check the tightness of the furnace tube.
[0083] 4. Heating: Raise the temperature to 1050°C and introduce nitrogen throughout the process.
[0084] 5. Preliminary stage of constant temperature oxidation: At 1050°C, nitrogen, oxygen and water are introduced for 6000s of second step oxidation with a gas flow rate of 50000sccm, in which the oxygen content accounts for 50% and the water content accounts for 50%.
[0085] 6. Late stage of constant temperature oxidation: At 1050°C, nitrogen, oxygen and hydrogen are introduced for 2000s of the third step of oxidation with a gas flow rate of 30000sccm, in which the oxygen content accounts for 80% and the hydrogen content accounts for 20%.
[0086] 7. Cooling: Only nitrogen is introduced and the temperature drops to 850°C.
[0087] 8. Exiting the boat: Break the vacuum, and the silicon nitride paddle will bring the oxidized silicon wafers out of the furnace tube.
[0088] Comparative Example 3
[0089] An oxidation process for a silicon-based product, comprising:
[0090] 1. Enter the boat, place the silicon wafer to be oxidized on the silicon nitride paddle, and place it in the quartz tube by the boat pusher mechanism.
[0091] 2. Evacuate the furnace, reduce the gas pressure in the furnace tube and raise the temperature to 800℃.
[0092] 3. Leak detection: Check the tightness of the furnace tube.
[0093] 4. Temperature-raising oxidation: The temperature is raised to 1050°C, and ozone and nitrogen are introduced throughout the process for 2000s of preliminary oxidation. The gas flow rate is 30000sccm, of which the ozone content accounts for 100%.
[0094] 5. Preliminary stage of constant temperature oxidation: At 1050°C, oxygen and water are introduced for 5000s of second step oxidation, with a gas flow rate of 50000sccm, in which the oxygen content accounts for 50% and the water content accounts for 50%.
[0095] 6. Late stage of constant temperature oxidation: At 1050°C, oxygen is introduced for 2000s of the third step of oxidation with a gas flow rate of 30000sccm, in which the oxygen content accounts for 100%.
[0096] 7. Cooling: Only nitrogen is introduced and the temperature drops to 850°C.
[0097] 8. Exiting the boat: Break the vacuum, and the silicon nitride paddle will bring the oxidized silicon wafers out of the furnace tube.
[0098] The oxidation temperature and duration were statistically analyzed using the preparation processes of the embodiment and the comparative example, and the thickness of the oxide layer, the fragmentation rate, and the minority carrier lifetime of the silicon wafer after oxidation were tested.
[0099] Oxide layer thickness: detected by laser ellipsometer;
[0100] Minority carrier lifetime of silicon wafer after oxidation: minority carrier lifetime tester - sinton equipment test lifetime;
[0101] Fragmentation rate: Automatic loading and unloading, and self-counting.
[0102] The detection results of the above detection method are shown in Tables 1 and 2 below.
[0103] Table 1
[0104]
[0105] Table 2
[0106]
[0107] From Table 1 and Table 2 above, we can see that: in the early stage of oxidation, the introduction of ozone helps to increase the oxidation rate of silicon wafers. In the later stage of oxidation, the introduction of hydrogen helps to increase the minority carrier lifetime of silicon wafers. The combined process of ozone, water vapor and hydrogen helps to reduce the fragmentation rate of silicon wafers.
[0108] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.
Claims
1. An oxidation process for silicon-based products, characterized in that: include: In the initial oxidation stage, ozone is introduced during the heating process for treatment; In the second oxidation stage, water and oxygen are introduced for treatment at the early stage of constant temperature oxidation; In the third step, oxidation, oxygen and hydrogen are introduced for treatment at the end of constant temperature oxidation.
2. The process according to claim 1, characterized in that The temperature of isothermal oxidation is 1000-1050℃.
3. The process according to claim 1 or 2, characterized in that The treatment time of the initial oxidation stage is 500-2000s; And / or, the gas flow rate in the initial oxidation stage is 3000-30000 sccm, wherein the content of ozone is 50-100%.
4. The process according to any one of claims 1 to 3, characterized in that The treatment time of the second oxidation stage is 1000-5000s; And / or, in the second oxidation stage, the gas flow rate is 5000-50000 sccm, wherein the water content is 1%-50%.
5. The process according to any one of claims 1 to 4, characterized in that The treatment time of the third oxidation stage is 500-2000s; And / or, in the third oxidation stage, the gas flow rate is 3000-30000 sccm, wherein the content of hydrogen is ≤20%.
6. The process according to any one of claims 1 to 5, characterized in that The oxidation process is carried out under a protective atmosphere.
7. The process according to claim 6, characterized in that The protective atmosphere includes nitrogen.
8. An oxide layer, characterized in that The method is prepared by the process described in any one of claims 1 to 7.
9. A silicon-based product, characterized in that: The oxide layer according to claim 8 is provided thereon.
10. The silicon-based product according to claim 9, characterized in that: The silicon-based product is a solar cell, preferably a TOPCon cell.