Polishing system of germanium single crystal wafer for high-flatness ultrathin solar cell

Abstract

The utility model relates to a polishing system of a germanium single crystal wafer for a high-flatness ultra-thin solar cell, which comprises a rough polishing mechanism, a rough polishing mechanism and a polishing mechanism, the rough polishing mechanism comprises a rough polishing machine fixed disc, rough polishing cloth arranged on the upper end face of the rough polishing machine fixed disc, a rough polishing grinding head arranged above the rough polishing machine fixed disc, and a rough polishing ceramic disc arranged at the grinding end of the rough polishing grinding head; the semi-fine polishing mechanism comprises a semi-fine polishing machine fixed disc, semi-fine polishing cloth arranged on the upper end face of the semi-fine polishing machine fixed disc, a semi-fine polishing grinding head arranged above the semi-fine polishing machine fixed disc and a semi-fine polishing ceramic disc arranged at the grinding end of the semi-fine polishing grinding head. The fine polishing mechanism comprises a fine polishing machine fixed disc, fine polishing cloth arranged on the upper end face of the fine polishing machine fixed disc, a fine polishing grinding head arranged above the fine polishing machine fixed disc and a fine polishing ceramic disc arranged at the grinding end of the fine polishing grinding head. By means of rough polishing, surface attachments and stains can be removed, machining allowance can be rapidly removed, efficiency is improved, and size control and flatness can be gradually achieved through semi-fine polishing and fine polishing.

Description

Technical Field

[0001] This utility model relates to a polishing system, specifically a polishing system for germanium single-crystal wafers for high-flatness ultra-thin solar cells. Background Technology

[0002] Germanium not only possesses a lattice constant and coefficient of thermal expansion similar to gallium arsenide (GaAs), but also exhibits excellent high-temperature resistance and radiation resistance, making it the most ideal substrate material for multi-junction GaAs solar cells used in space. Germanium single-crystal polished wafers not only provide support in the cell structure but also participate in photoelectric conversion through epitaxial growth to fabricate the bottom cell, thus influencing the conversion efficiency of multi-junction GaAs solar cells used in space. With the development of science and technology, the mainstream thickness of germanium single-crystal polished wafers has been reduced to 140±10μm (ultra-thin). Strict requirements are placed on the geometric parameters of germanium single-crystal polished wafers, requiring a flatness TTV ≤ 5μm and a mechanical strength ≥ 6lbf.

[0003] Existing systems for polishing germanium single crystal wafers for ultra-thin solar cells are relatively simple, typically employing CMP polishing. Polishing involves coarse polishing with polyurethane coarse polishing cloth followed by fine polishing with woven fine polishing cloth. The polishing time often exceeds 60 minutes per cycle, resulting in poor wafer geometry parameters (TTV BOW), high surface defect rate, numerous haze spots and scratches on the polished wafer surface, uneven and dark surface, low strength, and poor flatness, which seriously affect the epitaxial quality of the polished wafer. Utility Model Content

[0004] The purpose of this invention is to overcome at least one of the defects in the prior art and provide a polishing system for germanium single wafers for high-flatness ultra-thin solar cells.

[0005] The objective of this utility model can be achieved through the following technical solutions:

[0006] A polishing system for high-flatness ultrathin solar cells using germanium single wafers includes:

[0007] The coarse polishing mechanism includes: a coarse polishing machine plate, a coarse polishing cloth disposed on the upper surface of the coarse polishing machine plate, a coarse polishing grinding head disposed above the coarse polishing machine plate, and a coarse polishing ceramic disc disposed at the grinding end of the coarse polishing grinding head, wherein the germanium single crystal wafer to be coarsely polished is placed in the coarse polishing ceramic disc.

[0008] The semi-finish polishing mechanism includes: a semi-finish polishing machine plate, a semi-finish polishing cloth disposed on the upper surface of the semi-finish polishing machine plate, a semi-finish polishing grinding head disposed above the semi-finish polishing machine plate, and a semi-finish polishing ceramic disc disposed at the grinding end of the semi-finish polishing grinding head. The germanium single crystal wafer that has undergone coarse polishing is placed in the semi-finish polishing ceramic disc.

[0009] The fine polishing mechanism includes: a fine polishing machine plate, a fine polishing cloth disposed on the upper surface of the fine polishing machine plate, a fine polishing grinding head disposed above the fine polishing machine plate, and a fine polishing ceramic disc disposed at the grinding end of the fine polishing grinding head. The germanium single crystal wafer that has undergone semi-fine polishing is placed in the fine polishing ceramic disc.

[0010] Furthermore, the coarse polishing machine plate includes a coarse polishing worktable, a coarse polishing pad disposed on the coarse polishing worktable, and a coarse polishing cloth disposed on the coarse polishing pad.

[0011] Furthermore, the coarse polishing cloth is a JP-G-51 polishing cloth.

[0012] Furthermore, a coarse polishing fluid pipeline is also provided above the fixed plate of the coarse polishing machine.

[0013] Furthermore, the semi-finish polishing machine plate includes a semi-finish polishing worktable, a semi-finish polishing pad disposed on the semi-finish polishing worktable, and a semi-finish polishing cloth disposed on the semi-finish polishing pad.

[0014] Furthermore, the semi-finished polishing cloth is a polishing cloth of model F0JIB0-850.

[0015] Furthermore, a semi-finish polishing fluid pipeline is also provided above the fixed plate of the semi-finish polishing machine.

[0016] Furthermore, the polishing machine plate includes a polishing worktable, a polishing pad disposed on the polishing worktable, and a polishing cloth disposed on the polishing pad.

[0017] Furthermore, the polishing cloth is a 530N7501 polishing cloth.

[0018] Furthermore, a fine polishing fluid pipeline is also provided above the fixed plate of the fine polishing machine.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] (1) This utility model provides a polishing system for germanium single wafers for high-flatness ultra-thin solar cells. The system adds a semi-finish polishing mechanism to the rough polishing mechanism and the fine polishing mechanism. The rough polishing can remove surface deposits, stains and quickly remove processing allowances to improve efficiency. The semi-finish polishing mechanism and the fine polishing mechanism can gradually achieve size control and flatness. Specifically, although the rough polishing removes most of the allowances and obvious defects, it still leaves deep scratches and a certain degree of roughness. The semi-finish polishing can further reduce the depth and width of these scratches, significantly improve the surface roughness, lay a better foundation for fine polishing, and ultimately make the surface smoother after fine polishing, achieving higher quality requirements. In addition, it can more effectively remove some minor defects that may be generated during the rough polishing process, such as residual stress concentration points and micro-cracks on the surface. It can also correct the surface shape errors that may be caused by rough polishing, improve the flatness and accuracy of the surface, reduce the adverse effects caused by these defects during fine polishing, and reduce the surface defect rate of the final product.

[0021] (2) Existing technologies transition directly from rough polishing to fine polishing. Rough polishing requires removing a large amount of material to quickly approach the final dimensions, which may result in poor surface quality. Fine polishing, on the other hand, requires a longer time to remove the traces left by rough polishing. This invention, by incorporating semi-fine polishing, can share some of the workload, allowing rough polishing to focus more on quickly removing excess material and improving its efficiency. Fine polishing, however, is mainly used to achieve a high-quality final surface, thereby optimizing the entire polishing process, reducing the time spent on fine polishing, and improving production efficiency. Moreover, it reduces the costs associated with repeatedly performing rough and fine polishing to meet quality requirements, such as material, energy, and equipment wear. At the same time, the presence of semi-fine polishing makes the polishing process more stable and controllable, reducing the scrap rate caused by quality issues and further saving production costs. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the coarse polishing mechanism in the embodiment;

[0023] Figure 2 This is a schematic diagram of the semi-finishing polishing mechanism in the embodiment;

[0024] Figure 3 This is a schematic diagram of the polishing mechanism in the embodiment;

[0025] The numbers in the diagram indicate: 1-Rough polishing table; 2-Rough polishing pad; 3-Rough polishing slurry line; 4-Rough polishing cloth; 5-Germanium single crystal wafer to be rough polished; 6-Rough polishing ceramic disc; 7-Rough polishing head; 8-Semi-fine polishing table; 9-Semi-fine polishing pad; 10-Semi-fine polishing slurry line; 11-Semi-fine polishing cloth; 12-Germanium single crystal wafer after rough polishing; 13-Semi-fine polishing ceramic disc; 14-Semi-fine polishing head; 15-Fine polishing table; 16-Fine polishing pad; 17-Fine polishing slurry line; 18-Fine polishing cloth; 19-Germanium single crystal wafer after semi-fine polishing; 20-Fine polishing ceramic disc; 21-Fine polishing head. Detailed Implementation

[0026] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0027] Example

[0028] This embodiment describes a polishing system for germanium single-wafer crystals used in high-flatness ultra-thin solar cells. The specific structure is shown in [link to specific description]. Figure 1-3 ,include:

[0029] The coarse polishing mechanism includes: a coarse polishing machine plate, a coarse polishing cloth 4 disposed on the upper surface of the coarse polishing machine plate, a coarse polishing grinding head 7 disposed above the coarse polishing machine plate, and a coarse polishing ceramic disk 6 disposed at the grinding end of the coarse polishing grinding head 7. The germanium single crystal wafer to be coarsely polished is placed in the coarse polishing ceramic disk 6.

[0030] The semi-finish polishing mechanism includes: a semi-finish polishing machine plate, a semi-finish polishing cloth 11 disposed on the upper surface of the semi-finish polishing machine plate, a semi-finish polishing grinding head 14 disposed above the semi-finish polishing machine plate, and a semi-finish polishing ceramic disc 13 disposed at the grinding end of the semi-finish polishing grinding head 14, wherein the germanium single crystal wafer that has undergone coarse polishing is placed in the semi-finish polishing ceramic disc 13.

[0031] The fine polishing mechanism includes: a fine polishing machine plate, a fine polishing cloth 18 disposed on the upper surface of the fine polishing machine plate, a fine polishing grinding head 21 disposed above the fine polishing machine plate, and a fine polishing ceramic disc 20 disposed at the grinding end of the fine polishing grinding head 21. The germanium single crystal wafer that has undergone semi-fine polishing is placed in the fine polishing ceramic disc 20.

[0032] In this embodiment, the coarse polishing machine plate includes a coarse polishing worktable 1, a coarse polishing pad 2 disposed on the coarse polishing worktable 1, and a coarse polishing cloth 4 disposed on the coarse polishing pad 2. The coarse polishing cloth 4 is a JP-G-51 polishing cloth. A coarse polishing fluid pipeline 3 is also disposed above the coarse polishing machine plate.

[0033] In this embodiment, the semi-finish polishing machine platen includes a semi-finish polishing worktable 8, a semi-finish polishing pad 9 disposed on the semi-finish polishing worktable 8, and a semi-finish polishing cloth 11 disposed on the semi-finish polishing pad 9. The semi-finish polishing cloth 11 is a polishing cloth of model F0JIB0-850. A semi-finish polishing slurry pipeline 10 is also disposed above the semi-finish polishing machine platen.

[0034] In this embodiment, the polishing machine platen includes a polishing worktable 15, a polishing pad 16 disposed on the polishing worktable 15, and a polishing cloth 18 disposed on the polishing pad 16. The polishing cloth 18 is a 530N7501 polishing cloth. A polishing fluid pipeline 17 is also disposed above the polishing machine platen.

[0035] Working principle:

[0036] The system provided in this embodiment adds a semi-finishing polishing mechanism to the roughing and finishing polishing mechanisms. Roughing removes surface deposits and stains, and quickly removes machining allowances, improving efficiency. The semi-finishing and finishing polishing mechanisms can gradually achieve dimensional control and flatness improvement. Specifically, although roughing removes most of the allowances and obvious defects, it still leaves deep scratches and a certain degree of roughness. Semi-finishing polishing can further reduce the depth and width of these scratches, significantly improving surface roughness and laying a better foundation for finishing polishing. Ultimately, the finished surface is smoother and meets higher quality requirements. In addition, it can more effectively remove some minor defects that may occur during roughing, such as residual stress concentration points and microcracks on the surface. It can also correct surface shape errors that may be caused by roughing, improve surface flatness and precision, reduce the adverse effects of these defects during finishing polishing, and lower the surface defect rate of the final product.

[0037] Furthermore, existing technologies transition directly from rough polishing to fine polishing. Rough polishing requires removing a significant amount of material to quickly approach the final dimensions, which can lead to poor surface quality. Fine polishing, on the other hand, takes a considerable amount of time to remove the marks left by rough polishing. This invention, by incorporating semi-fine polishing, can distribute some of the workload, allowing rough polishing to focus more on quickly removing excess material, while fine polishing is primarily used to achieve a high-quality final surface. This optimizes the entire polishing process, reduces fine polishing time, and improves production efficiency. Moreover, it reduces the costs associated with repeatedly performing rough and fine polishing to meet quality requirements, such as material, energy, and equipment wear. Simultaneously, the presence of semi-fine polishing makes the polishing process more stable and controllable, reducing the scrap rate due to quality issues and further saving production costs.

[0038] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of this utility model without departing from its technical solution shall still fall within the protection scope of this utility model.

Claims

1. A polishing system for germanium single-wafer wafers for high-flatness ultra-thin solar cells, characterized in that, It includes: The rough polishing mechanism includes: a rough polishing machine chuck, a rough polishing cloth (4) arranged on the upper end face of the rough polishing machine chuck, a rough polishing head (7) arranged above the rough polishing machine chuck, and a rough polishing ceramic disc (6) arranged on the grinding end of the rough polishing head (7). The germanium single crystal wafer to be rough polished is placed in the rough polishing ceramic disc (6); The semi-precision polishing mechanism includes: a semi-precision polishing machine chuck, a semi-precision polishing cloth (11) arranged on the upper end face of the semi-precision polishing machine chuck, a semi-precision polishing head (14) arranged above the semi-precision polishing machine chuck, and a semi-precision polishing ceramic disc (13) arranged on the grinding end of the semi-precision polishing head (14). The germanium single crystal wafer after rough polishing is placed in the semi-precision polishing ceramic disc (13); The precision polishing mechanism includes: a precision polishing machine chuck, a precision polishing cloth (18) arranged on the upper end face of the precision polishing machine chuck, a precision polishing head (21) arranged above the precision polishing machine chuck, and a precision polishing ceramic disc (20) arranged on the grinding end of the precision polishing head (21). The germanium single crystal wafer after semi-precision polishing is placed in the precision polishing ceramic disc (20).

2. The polishing system of a high flatness, ultra-thin single crystal germanium wafer for solar cells according to claim 1, wherein The rough polishing machine chuck includes a rough polishing workbench (1) and a rough polishing pad (2) arranged on the rough polishing workbench (1). The rough polishing cloth (4) is arranged on the rough polishing pad (2).

3. The polishing system of a high flatness, ultra-thin single crystal germanium wafer for solar cells according to claim 1, wherein, The rough polishing cloth (4) is a polishing cloth of model JP-G-51.

4. The polishing system of a high flatness, ultra-thin single crystal germanium wafer for solar cells according to claim 1, wherein, A rough polishing grinding liquid pipeline (3) is further arranged above the rough polishing machine chuck.

5. The polishing system of a high flatness, ultra-thin single crystal germanium wafer for solar cells according to claim 1, wherein, The semi-precision polishing machine chuck includes a semi-precision polishing workbench (8) and a semi-precision polishing pad (9) arranged on the semi-precision polishing workbench (8). The semi-precision polishing cloth (11) is arranged on the semi-precision polishing pad (9).

6. The polishing system of a high flatness, ultra-thin single crystal germanium wafer for solar cells according to claim 1, wherein, The semi-precision polishing cloth (11) is a polishing cloth of model F0JIB0-850.

7. The polishing system of a high flatness, ultra-thin single crystal germanium wafer for solar cells according to claim 1, wherein, A semi-precision polishing grinding liquid pipeline (10) is further arranged above the semi-precision polishing machine chuck.

8. The polishing system of a high flatness, ultra-thin single crystal germanium wafer for solar cells according to claim 1, wherein, The precision polishing machine chuck includes a precision polishing workbench (15) and a precision polishing pad (16) arranged on the precision polishing workbench (15). The precision polishing cloth (18) is arranged on the precision polishing pad (16).

9. The polishing system of a high flatness, ultra-thin single crystal germanium wafer for solar cells according to claim 1, wherein, The precision polishing cloth (18) is a polishing cloth of model 530N7501.

10. The polishing system of a high flatness, ultra-thin, single crystal germanium wafer for solar cells of claim 1, wherein, A precision polishing grinding liquid pipeline (17) is further arranged above the precision polishing machine chuck.

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