Production method of polycrystalline silicon chips

Abstract

The invention provides a production method of polycrystalline silicon chips. The production method includes: preparing polycrystalline silicon ingots; cutting the polycrystalline silicon ingots into polycrystalline silicon chips. The steps for cutting the polycrystalline silicon into silicon chips include: cutting the polycrystalline silicon ingots into silicon blocks along the growing direction of the crystal lattice; stacking at least two silicon blocks and aligning and bonding the two bigger side faces of the two silicon blocks along a length direction; cutting the silicon blocks into silicon strips along a direction vertical to the length direction of the silicon blocks; and cutting the silicon strips into silicon chips along a growing direction of the crystal lattice. With the production method of polycrystalline silicon, the existing cutting method that the polycrystalline silicon blocks are cut along a direction vertical to the crystal lattice growth direction is changed into a cutting method that the polycrystalline silicon blocks are cut along a direction parallel to the crystal lattice growth direction, so that crystal particles of single silicon chips are expanded and amplified, distribution density of defects such as crystal boundary and dislocation is decreased and inner quality factors of battery pieces are improved.

Description

technical field [0001] The invention relates to the technical field of semiconductor processing, and more specifically, relates to a production method of a polycrystalline silicon wafer. Background technique [0002] Silicon is a very important semiconductor material, widely used in diodes, light emitting devices, solar cells and other fields. In the fast-growing photovoltaic industry, high efficiency and low cost have always been the two main points of competition, and crystalline silicon, as the current main solar cell material, has always occupied an absolute advantage due to its high efficiency and stability. [0003] At present, the entire solar polysilicon cell industry is in the period of reducing costs and innovating the processing technology of each link to improve the conversion efficiency of solar cells and other important internal quality factors. Ingot technology to avoid the generation of microcrystalline defects, even using quasi-single crystal ingot technolo...

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Problems solved by technology

[0004] Known from the internal structure of polycrystalline silicon ingots, the crystal growth process is mainly a process in which crystal nuclei are formed from the bottom of the crucible and gradually grow up with changes in the thermal field. In the existing future, try to increase the single crystal lattice area on each silicon wafer. Reduce the distribution density of defects such as grain boundaries and dislocations, and adopt single crystal ingot technology in the polycrystalline ingot casting process, that is, in the initial stage of ingot batching, lay a layer of single crystal material on the bottom of the crucible to induce crystal growth, also known as seed crystal , and do not make it penetrate during the melting stage of the silicon material, but retain the seed crystal at the bottom of the crucible as the crystal nucleus to start crystal growth. With the change of the thermal field process, the crystal grows from bottom to top in the vertical direction, through directional solidification Finally, a polycrystalline silicon ingot with super large crystal grains can be obtained, and then the polycrystalline silicon ingot is processed into slices. The existing slice process is to cut the polycrystalline silicon ingot into equal sizes along the horizontal and vertical directions on the upper end surface of the polycrystalline silicon ingot. The small cuboid is cut into the required silicon slices along the sides of the small cuboid parallel to the bottom surface by wire cutting. However, when cutting the small cuboid, it is perpendicular to the growth direction of the crystal, resulting in grain boundaries and The distribution density of defects such as dislocations is large, and the presence of conductive impurities in the densely packed grain boundaries makes the leakage current of the cell large, thus affecting the electrical performance

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