Method for reducing occurrence rate of pore piece in crystal pulling process, single-crystal crystal bar and application of single-crystal crystal bar

Abstract

The invention provides a method for reducing the occurrence rate of pore pieces in the crystal pulling process, a single crystal bar and application, and relates to the technical field of single crystal pulling, in the charging process, a quartz crucible is filled with a large-size silicon material and a small-size silicon material according to the weight ratio of (0-3): (1-4), gaps between the silicon materials and gaps between the silicon materials and the quartz crucible are reduced, and the occurrence rate of pore pieces is reduced; therefore, only a small amount of bubbles or even no bubbles are solidified in the single crystal in the crystal pulling process, so that the number of silicon wafers with air holes after slicing is reduced, and the occurrence rate of the air hole wafers is further reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of single crystal pulling, and in particular relates to a method for reducing the occurrence rate of pore sheets in a crystal pulling process, a single crystal rod and applications. Background Art

[0002] The main steps of pulling single crystal silicon using the CZ method include loading, evacuating, chemical reaction, stabilizing, seeding, shoulder release, shoulder rotation, equal diameter, finishing, cooling, etc. The single crystal silicon wafers produced normally through the above steps should be uniform and complete. However, when bubbles solidify in the single crystal during the crystal pulling process, silicon wafers with pores, i.e. porous wafers, will be produced after slicing.

[0003] Porous sheets have voids on the surface of silicon wafers, which is a fatal defect for chip manufacturing processes that require fine processing. Therefore, they cannot be used in any devices and can only be scrapped. Porous sheets will also be considered unqualified products, and porous sheets will reduce the product qualification rate.

[0004] During the crystal pulling process, polysilicon material and dopants are loaded into a quartz crucible, and the heater in the single crystal furnace is turned on to heat up, causing the silicon material to melt and become molten silicon. However, due to the gaps between the silicon materials and the silicon materials and the walls of the quartz crucible, a large number of bubbles will be mixed in the molten silicon. At the same time, the viscosity of the molten silicon is high and is affected by its internal pressure, so the bubbles are not easy to remove, resulting in these bubbles entering the crystal during the crystal pulling process and forming pores inside the crystal rod, forming porous sheets after slicing. Summary of the invention

[0005] In view of this, the present invention provides a method for reducing the occurrence rate of pore sheets during a crystal pulling process.

[0006] It is also necessary to provide a single crystal ingot.

[0007] It is also necessary to provide a silicon wafer.

[0008] It is also necessary to provide a chip.

[0009] The technical solution adopted by the present invention to solve its technical problem is: A method for reducing the occurrence rate of pores in a crystal pulling process, wherein during the charging process, the weight ratio of large-sized silicon materials to small-sized silicon materials is improved to reduce the gaps between silicon materials and silicon materials and between silicon materials and a quartz crucible, thereby reducing the amount of bubbles generated; Among them: the weight ratio of large-size silicon material to small-size silicon material is 0-3:1-4.

[0010] Preferably, the weight ratio of the large-size silicon material to the small-size silicon material is 1-3:1-4.

[0011] Preferably, the weight ratio of the large-size silicon material to the small-size silicon material is 1-2:1-3.

[0012] Preferably, the difference in particle size between the large-sized silicon material and the small-sized silicon material is 1 cm-10 cm.

[0013] Preferably, when silicon materials are loaded into the quartz crucible, small-sized silicon materials are loaded first, and then large-sized silicon materials are loaded.

[0014] Preferably, when silicon material is loaded into the quartz crucible, small-sized silicon material is first loaded at the bottom of the quartz crucible, and large-sized silicon material and small-sized silicon material are loaded in layers and staggered at the R corner of the quartz crucible and the lower part of the straight arm of the quartz crucible, and large-sized silicon material is loaded on the straight wall of the quartz crucible.

[0015] A single crystal ingot is obtained by pulling using the method for reducing the occurrence rate of pore sheets during the crystal pulling process as described above.

[0016] A silicon wafer is obtained by cutting the single crystal ingot as described above.

[0017] A chip is made from the silicon wafer as described above.

[0018] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method for reducing the occurrence rate of pore sheets during a crystal pulling process. During the charging process, large-sized silicon materials and small-sized silicon materials are loaded into a quartz crucible in a weight ratio of 0-3:1-4, and the gaps between the silicon materials and the silicon materials and the quartz crucible are reduced to reduce the amount of bubbles generated, so that only a small amount of bubbles or even no bubbles are solidified in the single crystal during the crystal pulling process, thereby reducing the number of silicon wafers with pores after slicing, thereby reducing the occurrence rate of pore sheets and improving the product qualification rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the structure of a quartz crucible.

[0020] In the figure: a quartz crucible 10 , a bottom 100 , an R corner 200 , and a straight wall 300 . DETAILED DESCRIPTION

[0021] The technical solutions and technical effects of the embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings of the present invention.

[0022] A method for reducing the occurrence rate of pores in a crystal pulling process, wherein during the charging process, the weight ratio of large-sized silicon materials to small-sized silicon materials is improved to reduce the gaps between silicon materials and silicon materials and between silicon materials and a quartz crucible, thereby reducing the amount of bubbles generated; Among them: the weight ratio of large-size silicon material to small-size silicon material is 0-3:1-4.

[0023] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method for reducing the occurrence rate of pore sheets during a crystal pulling process. During the charging process, large-sized silicon materials and small-sized silicon materials are loaded into a quartz crucible in a weight ratio of 0-3:1-4, and the gaps between the silicon materials and the silicon materials and the quartz crucible are reduced to reduce the amount of bubbles generated, so that only a small amount of bubbles or even no bubbles are solidified in the single crystal during the crystal pulling process, thereby reducing the number of silicon wafers with pores after slicing, thereby reducing the occurrence rate of pore sheets and improving the product qualification rate.

[0024] Furthermore, the weight ratio of the large-size silicon material to the small-size silicon material is 1-3:1-4; when the large-size silicon material ratio is higher, the gaps between the silicon materials and the silicon materials, and between the silicon materials and the wall of the quartz crucible are larger, and the amount of bubbles in the silicon melt will also be larger, which will not only increase the incidence of pore sheets, but also when the bubbles in the silicon melt increase, it will cause broken edges during the single crystal growth stage, causing the crystal to lose its single crystal structure and become polycrystalline, resulting in a decrease in the crystallization rate; when the small-size silicon material ratio is higher, the gaps between the silicon materials and the silicon materials, and between the silicon materials and the wall of the quartz crucible are smaller, and the amount of bubbles in the silicon melt will be smaller, but the small-size silicon material has a larger contact area with the wall of the quartz crucible, which may cause part of the silicon material to stick to the side wall of the quartz crucible during the material smelting process, and the weight of the silicon material itself may pull and deform the side wall of the quartz crucible, or even cause edge collapse. If severe deformation or severe edge collapse occurs, there is a risk of silicon leakage.

[0025] Furthermore, the weight ratio of the large-size silicon material to the small-size silicon material is 1-2:1-3.

[0026] Furthermore, the difference in particle size between the large-sized silicon material and the small-sized silicon material is 1 cm-10 cm.

[0027] Furthermore, the particle size of the large-sized silicon material is 6 cm-12 cm, and the particle size of the small-sized silicon material is 2 cm-5 cm.

[0028] Furthermore, the shapes of the large-sized silicon material and the small-sized silicon material are not necessarily uniform and regular spheres, and there may also be blocks with irregular edges.

[0029] Please see Figure 1 Furthermore, the quartz crucible 10 includes a bottom 100, an R angle 200, and a straight wall 300 from bottom to top, and the bottom 100, the R angle 200, and the straight wall 300 are integrally formed.

[0030] Furthermore, when the silicon material is filled into the quartz crucible, the small-sized silicon material is filled first, and then the large-sized silicon material is filled.

[0031] Furthermore, when silicon material is filled into the quartz crucible, small-sized silicon material is first filled into the bottom 100 of the quartz crucible, and large-sized silicon material and small-sized silicon material are filled in a layered and staggered manner at the R corner 200 of the quartz crucible and the lower part of the straight arm 300 of the quartz crucible, and large-sized silicon material is filled into the straight wall 300 of the quartz crucible.

[0032] Specifically, according to the various characteristics of different positions of the quartz crucible and different depths of the silicon melt, small-sized silicon materials are first loaded into the bottom 100 of the quartz crucible to reduce the amount of bubbles generated in the deep silicon melt, and large-sized silicon materials are loaded into the straight wall 300 of the quartz crucible to make point contact between the silicon materials and the quartz crucible, thereby reducing the possibility of silicon materials hanging on the edge. At the same time, if large-sized silicon materials hang on the edge, they are more likely to rely on their own weight to break away from the quartz crucible wall, thereby avoiding the collapse and deformation of the quartz crucible. The R corner 200 of the quartz crucible and the lower part of the straight arm 300 are loaded in a layered and staggered manner with large-sized silicon materials and small-sized silicon materials, so that the small-sized silicon materials can fill the gaps between the large-sized silicon materials, thereby minimizing the amount of bubbles.

[0033] A single crystal ingot is obtained by pulling using the method for reducing the occurrence rate of pore sheets during the crystal pulling process as described above.

[0034] A silicon wafer is obtained by cutting the single crystal ingot as described above.

[0035] A chip is made from the silicon wafer as described above.

[0036] The use of the present invention is described by the following examples. Embodiment 1:

[0037] An 8-inch boron-doped crystal rod is pulled with a diameter of 200mm. 150Kg of small-sized silicon material is fully loaded into a quartz crucible. The particle size of the small-sized silicon material is about 3-4cm. The argon flow rate is 40slm-80slm, the furnace pressure is 5Kpa-15Kpa, the crystal rod speed is 10rpm-20rpm, and the crucible speed is 0.8rpm-2.5rpm. Then, the process of evacuating, chemically treating, stabilizing, seeding, shouldering, shoulder rotation, equalizing diameter, finishing, and cooling the pulled crystal rod is performed, and the pulled crystal rod is sliced ​​to obtain silicon wafers. Embodiment 2:

[0038] An 8-inch boron-doped crystal rod is pulled with a diameter of 200mm. 30Kg of large-size silicon material and 120Kg of small-size silicon material are loaded in a quartz crucible. The small-size silicon material is loaded first and the large-size silicon material is loaded later. The particle size of the small-size silicon material is about 3-4cm, and the particle size of the large-size silicon material is about 8-10cm. The argon flow rate is 40slm-80slm, the furnace pressure is 5Kpa-15Kpa, the crystal rod speed is 10rpm-20rpm, and the crucible speed is 0.8rpm-2.5rpm. Then, the process of evacuating, chemicalizing, stabilizing, seeding, shouldering, shoulder rotation, equalizing diameter, finishing, and cooling is carried out to pull the crystal rod. The pulled crystal rod is sliced ​​to obtain silicon wafers. Embodiment 3:

[0039] An 8-inch boron-doped crystal rod is pulled with a diameter of 200mm. 50Kg of large-size silicon material and 100Kg of small-size silicon material are loaded in a quartz crucible. The small-size silicon material is loaded first and the large-size silicon material is loaded later. The particle size of the small-size silicon material is about 3-4cm, and the particle size of the large-size silicon material is about 8-10cm. The argon flow rate is 40slm-80slm, the furnace pressure is 5Kpa-15Kpa, the crystal rod speed is 10rpm-20rpm, and the crucible speed is 0.8rpm-2.5rpm. Then, the crystal rod is pulled by evacuating, chemically treating, stabilizing, seeding, shouldering, shoulder rotation, equalizing diameter, finishing, and cooling. The pulled crystal rod is sliced ​​to obtain silicon wafers. Embodiment 4:

[0040] Pull an 8-inch boron-doped crystal rod with a diameter of 200 mm. Load 50 kg of large-size silicon material and 100 kg of small-size silicon material in a quartz crucible. First, load the small-size silicon material at the bottom 100 of the quartz crucible. Then, load the large-size silicon material and the small-size silicon material in layers and in an alternating manner at the R corner 200 of the quartz crucible and the lower part of the straight arm 300 of the quartz crucible. The large-size silicon material is loaded at the straight wall 300 of the quartz crucible, and the particle size of the small-size silicon material is 200 mm. The diameter of the large-sized silicon material is about 3-4cm, and the particle size of the large-sized silicon material is about 8-10cm. The argon flow rate is 40slm-80slm, the furnace pressure is 5Kpa-15Kpa, the crystal rod speed is 10rpm-20rpm, and the crucible speed is 0.8rpm-2.5rpm. Then the crystal rod is pulled by evacuation, material processing, stabilization, crystal seeding, shoulder release, shoulder rotation, equal diameter, finishing, cooling and other processes. The pulled crystal rod is sliced ​​to obtain silicon wafers.

[0041] Comparative Example 1: An 8-inch boron-doped crystal rod is pulled with a diameter of 200mm. 120Kg of large-size silicon material and 30Kg of small-size silicon material are loaded in a quartz crucible. The small-size silicon material is loaded first and the large-size silicon material is loaded later. The particle size of the small-size silicon material is about 3-4cm, and the particle size of the large-size silicon material is about 8-10cm. The argon flow rate is 40slm-80slm, the furnace pressure is 5Kpa-15Kpa, the crystal rod speed is 10rpm-20rpm, and the crucible speed is 0.8rpm-2.5rpm. Then, the crystal rod is pulled by evacuation, chemical reaction, stabilization, seeding, shoulder release, shoulder rotation, equal diameter, finishing, and cooling. The pulled crystal rod is sliced ​​to obtain silicon wafers.

[0042] Comparative Example 2: When 150 kg of large-sized silicon material is fully loaded into the quartz crucible, the large-sized silicon material will exceed the upper edge of the quartz crucible after loading, provided that the total loading amount remains unchanged at 150 kg. If the crystal pulling experiment is continued, the material block will touch the heat shield, thus damaging the heat field components and failing to obtain a crystal rod.

[0043] The silicon wafers obtained in Examples 1-4 and Comparative Example 1 were processed into polished wafers, and the polished wafers were tested for pores using a pore detection device of model IIM-3000 (the detection range of IIM-3000 is ≥20 μm). The results of pore detection are shown in Table 1.

[0044] Table 1

[0045] Among them: the crystallization rate refers to the yield of silicon single crystals, that is, the weight of the single crystal rod after the crystal pulling is completed / the total amount of material input.

[0046] It can be seen from the results in Table 1 above that, under the condition of a certain crystallization rate, when the weight ratio of large-size silicon material to small-size silicon material is 0-3:1-4, the pore incidence is basically 0%; when the weight ratio of large-size silicon material to small-size silicon material is 1-3:1-4, not only the pore incidence is basically 0%, but also the silicon material hanging rate is greatly reduced; when the weight ratio of large-size silicon material to small-size silicon material is 1-2:1-3, not only the pore incidence is basically 0%, but also the silicon material hanging rate is 0%; when the weight ratio of large-size silicon material to small-size silicon material is 1-2:1-3, and the small-size silicon material is loaded at the bottom of the quartz crucible first, the large-size silicon material and the small-size silicon material are loaded in a layered and staggered manner at the R corner of the quartz crucible and the lower part of the straight arm of the quartz crucible, the large-size silicon material is loaded on the straight wall of the quartz crucible, the pore incidence is 0%, the hanging rate is 0%, and the crystallization rate reaches 78.6%.

[0047] What is disclosed above is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of rights of the present invention. A person skilled in the art can understand that all or part of the processes of the above embodiments and equivalent changes made according to the claims of the present invention still fall within the scope of the invention.

Claims

1. A method for reducing the occurrence rate of pores in a crystal pulling process, characterized in that: During the charging process, the weight ratio of large-sized silicon materials to small-sized silicon materials is improved to reduce the gaps between silicon materials and between silicon materials and quartz crucibles, thereby reducing the amount of bubbles generated; Among them: the weight ratio of large-size silicon material to small-size silicon material is 0-3:1-4.

2. The method for reducing the occurrence rate of pores in the crystal pulling process according to claim 1, characterized in that: The weight ratio of the large-size silicon material to the small-size silicon material is 1-3:1-4.

3. The method for reducing the occurrence rate of pores in the crystal pulling process according to claim 1, characterized in that: The weight ratio of the large-size silicon material to the small-size silicon material is 1-2:1-3.

4. The method for reducing the occurrence rate of pores in a crystal pulling process according to any one of claims 1 to 3, characterized in that: The difference in particle size between the large-sized silicon material and the small-sized silicon material is 1 cm-10 cm.

5. The method for reducing the occurrence rate of pore sheets during crystal pulling according to any one of claims 1 to 3, characterized in that: When filling the quartz crucible with silicon material, first fill the small-sized silicon material and then fill the large-sized silicon material.

6. The method for reducing the occurrence rate of pores in the crystal pulling process according to claim 3, characterized in that: When filling silicon material into the quartz crucible, small-sized silicon material is first filled at the bottom of the quartz crucible, and large-sized silicon material and small-sized silicon material are filled in a layered and staggered manner at the R corner of the quartz crucible and the lower part of the straight arm of the quartz crucible. Large-sized silicon material is filled on the straight wall of the quartz crucible.

7. A single crystal ingot, characterized in that: The crystal is pulled by using the method for reducing the occurrence rate of pore sheets during the crystal pulling process as described in any one of claims 1 to 6.

8. A silicon wafer, characterized in that: It is obtained by cutting the single crystal ingot as described in claim 7.

9. A chip, characterized in that: It is made using the silicon wafer as claimed in claim 8.

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