Plasma enhanced chemical vapor deposition equipment

Abstract

The invention provides a plasma enhanced chemical vapor deposition apparatus. The plasma enhanced chemical vapor deposition equipment comprises a cavity, a radio frequency power supply located outside the cavity and used for generating a radio frequency signal for exciting plasma, and a gas distribution plate assembly located in the cavity, located below a gas inlet and used for uniformizing reaction gas entering the cavity from the gas inlet. The upper electrode is positioned below the gas distribution plate assembly, and the bottom surface of the upper electrode is a concave surface; the electrode shielding layer is suspended below the upper electrode; the lower electrode is positioned at the bottom of the cavity, is grounded and is arranged opposite to the upper electrode; the electrode shielding layer comprises a plurality of dielectric units and a plurality of metal units, and when the plasma enhanced chemical vapor deposition equipment carries out a plasma enhanced chemical vapor deposition process, the plasma density fluctuation of areas corresponding to the plurality of dielectric units and the plurality of metal units does not exceed a preset range. According to the invention, the plasma distribution uniformity and the film forming uniformity can be improved.

Description

Technical Field

[0001] The present invention relates to the field of solar cell manufacturing, and particularly to a plasma enhanced chemical vapor deposition device. Background Art

[0002] Thin film / crystalline silicon heterojunction solar cells (hereinafter referred to as heterojunction solar cells, also known as HIT or SHJ solar cells) belong to the third generation of high-efficiency solar cell technology. It combines the advantages of the first-generation crystalline silicon and the second-generation silicon thin film, and has characteristics such as high conversion efficiency and low temperature coefficient. In particular, the conversion efficiency of double-sided heterojunction solar cells can reach more than 26%, having broad market prospects.

[0003] In the manufacturing of heterojunction solar cells, a plasma enhanced chemical vapor deposition (PECVD) process needs to be carried out through a PECVD device to deposit P-type amorphous silicon, N-type amorphous silicon, and intrinsic I-type amorphous silicon thin films on a silicon wafer. Refer to Figure 1 , which shows a schematic structural diagram of a prior art PECVD device. The PECVD device includes a cavity 10, and further includes a gas distribution plate assembly 11, an upper electrode 12, a shielding layer suspension rod 14, an electrode shielding layer 13, and a lower electrode 15 arranged in the cavity 10 from top to bottom. The top of the cavity 10 includes an air inlet 100. A radio frequency power supply 16 is located outside the cavity 10 and is electrically connected to the upper electrode 12 through a radio frequency input device 102 passing through the gas distribution plate assembly 11. The upper electrode 12 can be a gas shower head in the shape of a Gaussian surface.

[0004] The electrode shielding layer 13 is suspended below the upper electrode 12 to limit the standing wave effect in the radio frequency plasma cavity and the uneven distribution of plasma density in the cavity caused by the standing wave effect. As Figure 2 shown, the electrode shielding layer 13 may include a plurality of dielectric units 130, 131, 132, 133, 134, 135, 136, 137, 138. Each dielectric unit 130, 131, 132, 133, 134, 135, 136, 137, 138 can be a ceramic plate with uniform thickness. The adjacent side surfaces of adjacent dielectric units are provided with steps that are nested with each other in an uneven manner in the overlapping region M.

[0005] When the PECVD device is performing the PECVD process, the plasma density distribution is often uneven due to other reasons such as uneven gas distribution. There is a large difference in plasma density on different dielectric units 130, 131, 132, 133, 134, 135, 136, 137, and 138 of the entire electrode shielding layer 13, and sometimes even exceeds 10%. Such a large difference in plasma density will cause the coating to be very uneven.

[0006] Therefore, how to provide a plasma enhanced chemical vapor deposition device to improve the uniformity of plasma distribution and film formation has become a technical problem that needs to be solved urgently in the industry. Summary of the invention

[0007] In view of the above problems in the prior art, the present invention proposes a plasma enhanced chemical vapor deposition device, comprising:

[0008] a cavity, including an air inlet located at a top thereof;

[0009] A radio frequency power source, located outside the cavity, for generating a radio frequency signal for exciting the plasma;

[0010] A gas distribution plate assembly, located in the cavity and below the gas inlet, for uniformly distributing the reaction gas entering the cavity from the gas inlet;

[0011] an upper electrode, located in the cavity and below the gas distribution plate assembly, the bottom surface of the upper electrode being a concave surface;

[0012] an electrode shielding layer suspended below the upper electrode; and

[0013] A lower electrode, located at the bottom of the cavity and electrically connected to the ground, and arranged opposite to the upper electrode;

[0014] The electrode shielding layer includes a plurality of dielectric units and a plurality of metal units. When the plasma enhanced chemical vapor deposition device performs a plasma enhanced chemical vapor deposition process, the plasma density fluctuations in the regions corresponding to the plurality of dielectric units and the plurality of metal units do not exceed a predetermined range.

[0015] In one embodiment, the region corresponding to the plurality of metal units is the region of the electrode shielding layer that is closest to the air outlet.

[0016] In one embodiment, the plurality of metal units are located in a middle region of the electrode shielding layer.

[0017] In one embodiment, the upper electrode is a gas shower head, and the concave surface is a Gaussian surface or a stepped concave surface.

[0018] In one embodiment, the predetermined range is 2%-3%.

[0019] In one embodiment, each of the plurality of dielectric units is a square unit with a side length of 5-10 cm.

[0020] In one embodiment, each of the plurality of metal units is a square unit with a side length of 5-10 cm.

[0021] In one embodiment, adjacent dielectric units, or adjacent electrolyte units and metal units, or adjacent metal units overlap each other.

[0022] In one embodiment, adjacent sides of adjacent dielectric units, or adjacent electrolyte units and metal units, or adjacent metal units are provided with steps that are nested with each other in a concave-convex manner in the overlapping area.

[0023] In one embodiment, adjacent sides of adjacent dielectric units, or adjacent electrolyte units and metal units, or adjacent metal units are provided with grooves and protrusions that are nested with each other in a concave-convex manner in the overlapping area.

[0024] In one embodiment, the gas distribution plate assembly, the upper electrode, the electrode shielding layer, and the lower electrode are all square.

[0025] Compared with the prior art in which the electrode shielding layer is composed of a plurality of dielectric units, resulting in a lower plasma density at the edges or in the middle, the electrode shielding layer of the present invention includes a plurality of dielectric units and a plurality of metal units. When the plasma enhanced chemical vapor deposition process is carried out in the plasma enhanced chemical vapor deposition equipment, the plasma density fluctuation in the corresponding areas of the plurality of dielectric units and the plurality of metal units does not exceed a predetermined range. The present invention can improve the plasma distribution uniformity and the film formation uniformity. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] After reading the detailed description of the embodiments of the present disclosure in conjunction with the following drawings, the above features and advantages of the present invention can be better understood. In the drawings, the components are not necessarily drawn to scale, and components with similar relevant characteristics or features may have the same or similar reference numerals.

[0027] Figure 1 FIG. is a schematic structural diagram of an embodiment of a prior art plasma enhanced chemical vapor deposition equipment.

[0028] Figure 2 is Figure 1 a cross-sectional structural diagram of the electrode shielding layer 13 in

[0029] Figure 3Schematic diagram of the composition structure of the first embodiment of the plasma enhanced chemical vapor deposition equipment of the present invention.

[0030] Figure 4 is Figure 3 the schematic cross-sectional structure of the electrode shielding layer 13' in

[0031] Figure 5 Schematic diagram of the composition structure of the second embodiment of the plasma enhanced chemical vapor deposition equipment of the present invention.

[0032] Figure 6 is Figure 5 the schematic cross-sectional structure of the electrode shielding layer 13'' in Detailed implementation manners

[0033] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments to more clearly understand the purpose, features and advantages of the present invention. It should be understood that the aspects described below with reference to the accompanying drawings and specific embodiments are only exemplary and should not be construed as imposing any limitation on the protection scope of the present invention. Unless the context clearly indicates otherwise, the singular forms "a" and "the" include plural referents. The terms "first", "second" and similar terms used in this specification and the claims do not denote any order, quantity or importance, but are only used to distinguish different components.

[0034] Refer to Figures 3 to 4 , Figure 3 which is the schematic diagram of the composition structure of the first embodiment of the plasma enhanced chemical vapor deposition (PECVD) equipment of the present invention, Figure 4 is Figure 3 the schematic cross-sectional structure of the electrode shielding layer 13' in Figure 3As shown in the figure, the first embodiment of the PECVD device of the present invention includes a cavity 10, and further includes a gas distribution plate assembly 11, an upper electrode 12, a shielding layer suspension rod 14, an electrode shielding layer 13', and a lower electrode 15 arranged in the cavity 10 from top to bottom. A radio frequency power supply 16 is located outside the cavity 10 and is used to generate a radio frequency signal for exciting plasma. The top of the cavity 10 includes an air inlet 100, and the radio frequency power supply 16 is electrically connected to the upper electrode 12 through a radio frequency input device 102 passing through the gas distribution plate assembly 11. The upper electrode 12 is located in the cavity 10 and below the gas distribution plate assembly 11, and the bottom surface of the upper electrode 12 is a concave surface, and the concave surface can be a Gaussian surface or a stepped concave surface. The electrode shielding layer 13' is suspended below the upper electrode 12, and specifically can be suspended and connected through the shielding layer suspension rod 14. The shielding layer suspension rod 14 can be a metal rod, and its two ends are respectively fixed on the upper electrode 12 and the electrode shielding layer 13' through metal bolts or screws. The lower electrode 15 is located at the bottom of the cavity 10 and is electrically connected to the ground, and is arranged opposite to the upper electrode 12. The gas distribution plate assembly 11, the upper electrode 12, the electrode shielding layer 13', and the lower electrode 15 are all square. The electrode shielding layer 13' arranged below the upper electrode 12 can limit the standing wave effect in the radio frequency plasma cavity and the uneven distribution of plasma density in the cavity caused by the standing wave effect.

[0035] As Figure 4 shown, the electrode shielding layer 13' may include a plurality of dielectric units 131', 132', 133', 134', 135', 136', 137' and a plurality of metal units 130', 138'. Each dielectric unit 131', 132', 133', 134', 135', 136', 137' can be a ceramic plate with uniform thickness, and each metal unit 130', 138' can be an aluminum plate with uniform thickness. Adjacent dielectric units 131', 132', 133', 134', 135', 136', 137' or between adjacent electrolyte units and metal units 130' and 131', 137' and 138' or between adjacent metal units 130' and 130', 138' and 138' overlap with each other.

[0036] The adjacent side surfaces of adjacent dielectric units 131’, 132’, 133’, 134’, 135’, 136’, 137’ are provided with steps that are mutually concave-convex nested and fitted in the overlapping region M. Similarly, steps that are mutually concave-convex nested and fitted are provided in the overlapping region M between the adjacent side surfaces of the same adjacent electrolyte units and metal units 130’ and 131’, 137’ and 138’, and between adjacent metal units 130’ and 130’, 138’ and 138’. In other embodiments, grooves and protrusions that are mutually concave-convex nested and fitted are provided in the overlapping region M on the adjacent side surfaces between adjacent dielectric units 131’, 132’, 133’, 134’, 135’, 136’, 137’, adjacent electrolyte units and metal units 130’ and 131’, 137’ and 138’, or between adjacent metal units 130’ and 130’, 138’ and 138’, that is, a concave-convex fitting structure is formed.

[0037] When the plasma enhanced chemical vapor deposition equipment performs a plasma enhanced chemical vapor deposition process, the plasma density fluctuations in the corresponding regions of the plurality of dielectric units 131’, 132’, 133’, 134’, 135’, 136’, 137’ and the plurality of metal units 130’, 138’ do not exceed a predetermined range. The predetermined range is 2% - 3%. More specifically, the predetermined range can be, for example, 2%, 2.5% or 3%. By replacing the dielectric unit in the region with a lower plasma density with a metal unit, the plasma density in this region can be increased. The regions corresponding to the plurality of metal units 130’, 138’ are the regions where the electrode shielding layer 13’ is closest to the air extraction port. Each dielectric unit 131’, 132’, 133’, 134’, 135’, 136’, 137’ can be a square unit with a side length of 5 - 10 cm, and each metal unit 130’, 138’ can be a square unit with a side length of 5 - 10 cm.

[0038] See Figures 5 to 6 , Figure 5 is a schematic structural diagram of the composition of the second embodiment of the PECVD device of the present invention. Figure 6 is Figure 5 a cross-sectional structural diagram of the electrode shielding layer 13” in Figure 5 As shown in

[0039] As Figure 6As shown, the electrode shielding layer 13” may include a plurality of dielectric units 130”, 131”, 132”, 133”, 135”, 136”, 137”, 138” and a plurality of metal units 134”. The plurality of metal units 134” are located in the middle region of the electrode shielding layer 13”. Each of the dielectric units 130”, 131”, 132”, 133”, 135”, 136”, 137”, 138” may be a ceramic plate with a uniform thickness, and each of the metal units 134” may be an aluminum plate with a uniform thickness. Each of the dielectric units 130”, 131”, 132”, 133”, 135”, 136”, 137”, 138” may be a square unit with a side length of 5 - 10 cm, and each of the metal units 134” may be a square unit with a side length of 5 - 10 cm.

[0040] The adjacent dielectric units 130”, 131”, 132”, 133”, 135”, 136”, 137”, 138” or between the adjacent electrolyte units and metal units 133” and 134”, 134” and 135” or between the adjacent metal units 134” and 134” overlap with each other. When the plasma enhanced chemical vapor deposition equipment performs the plasma enhanced chemical vapor deposition process, the plasma density fluctuations in the corresponding regions of the plurality of dielectric units 130”, 131”, 132”, 133”, 135”, 136”, 137”, 138” and the plurality of metal units 134” do not exceed a predetermined range, and the predetermined range is 2% - 3%.

[0041] The adjacent sides of the adjacent dielectric units 130”, 131”, 132”, 133”, 135”, 136”, 137”, 138” are provided with steps that are nested with each other in a concave-convex manner in the overlapping region M. Similarly, the adjacent sides of the adjacent electrolyte units and metal units 130” and 131”, 137” and 138” are provided with steps that are nested with each other in a concave-convex manner in the overlapping region M. In other embodiments, the adjacent sides of the adjacent dielectric units 131”, 132”, 133”, 134”, 135”, 136”, 137”, the adjacent electrolyte units and metal units 133” and 134”, 134” and 135” or the adjacent metal units 134” and 134” are provided with grooves and protrusions that are nested with each other in a concave-convex manner in the overlapping region M.

[0042] In Figure 5In the second embodiment of the PECVD device of the present invention shown, since the metal unit 134” is located in the middle region of the electrode shielding layer 13”, the metal unit 134” is electrically connected to the upper electrode 12 through the shielding layer suspender 14. By adjusting the middle height of the upwardly concave surface at the bottom of the upper electrode 12, for example, reducing or increasing its middle height, the air flow below the upper electrode 12 can be adjusted, thereby further optimizing the film formation uniformity in the middle region.

[0043] In the PECVD device, the air extraction volume at the air extraction port is greater than that in other regions, resulting in the plasma density in the region closest to the air extraction port being less than that in other regions. Figure 3 In the first embodiment of the PECVD device of the present invention, the dielectric unit in the region closest to the air extraction port in the prior art is replaced with a metal unit, so that the plasma density fluctuations in the corresponding regions of the plurality of dielectric units and the plurality of metal units do not exceed a predetermined range. Figure 5 The second embodiment of the PECVD device of the present invention is an improvement for the case where the plasma density in the middle region of the electrode shielding layer is less than that in other regions, that is, the dielectric unit in the middle region of the electrode shielding layer in the prior art is replaced with a metal unit, so that the plasma density fluctuations in the corresponding regions of the plurality of dielectric units and the plurality of metal units do not exceed a predetermined range.

[0044] The plasma enhanced chemical vapor deposition device of the present invention includes a cavity, a radio frequency power supply located outside the cavity and used to generate an excitation plasma radio frequency signal, a gas distribution plate assembly located inside the cavity and below the air inlet and used to evenly distribute the reaction gas entering the cavity from the air inlet, an upper electrode located below the gas distribution plate assembly and having a concave bottom surface, an electrode shielding layer suspended below the upper electrode, and a lower electrode located at the bottom of the cavity and grounded and disposed opposite to the upper electrode; the electrode shielding layer includes a plurality of dielectric units and a plurality of metal units. When the plasma enhanced chemical vapor deposition process is carried out by the plasma enhanced chemical vapor deposition device, the plasma density fluctuations in the corresponding regions of the plurality of dielectric units and the plurality of metal units do not exceed a predetermined range. The present invention can improve the plasma distribution uniformity and the film formation uniformity.

[0045] The above embodiments are provided for those skilled in the art to implement or use the present invention. Those skilled in the art can make various modifications or changes to the above embodiments without departing from the inventive concept of the present invention. Therefore, the protection scope of the present invention is not limited by the above embodiments, but should be the maximum scope that conforms to the innovative features mentioned in the claims.

Claims

1. A plasma enhanced chemical vapor deposition device, comprising: A cavity, including an air inlet located at its top; A radio frequency power supply, located outside the cavity, for generating a radio frequency signal to excite plasma; A gas distribution plate assembly, located inside the cavity and below the air inlet, for evenly distributing the reaction gas entering the cavity from the air inlet; An upper electrode, located inside the cavity and below the gas distribution plate assembly, the bottom surface of the upper electrode being concave; An electrode shielding layer, suspended below the upper electrode; And A lower electrode, located at the bottom of the cavity and electrically connected to the ground, arranged opposite to the upper electrode; It is characterized in that the electrode shielding layer includes a plurality of dielectric units and a plurality of metal units, and when the plasma enhanced chemical vapor deposition device performs a plasma enhanced chemical vapor deposition process, the plasma density fluctuations in the corresponding regions of the plurality of dielectric units and the plurality of metal units do not exceed a predetermined range.

2. The plasma enhanced chemical vapor deposition apparatus according to claim 1, wherein The region corresponding to the plurality of metal units is the region of the electrode shielding layer closest to the air extraction port.

3. The plasma enhanced chemical vapor deposition apparatus according to claim 1, characterized in that The plurality of metal units are located in the middle region of the electrode shielding layer.

4. The plasma enhanced chemical vapor deposition apparatus according to claim 1, wherein The upper electrode is a gas shower head, and the concave surface is a Gaussian surface or a stepped concave surface.

5. The plasma enhanced chemical vapor deposition apparatus according to claim 1, wherein The predetermined range is 2% - 3%.

6. The plasma enhanced chemical vapor deposition apparatus according to claim 1, wherein Each dielectric unit in the plurality of dielectric units is a square unit with a side length of 5 - 10 cm, and each metal unit in the plurality of metal units is a square unit with a side length of 5 - 10 cm.

7. The plasma enhanced chemical vapor deposition apparatus according to claim 1, wherein Adjacent dielectric units, or adjacent electrolyte units and metal units, or adjacent metal units overlap each other.

8. The plasma enhanced chemical vapor deposition apparatus according to claim 7, wherein Adjacent sides of adjacent dielectric units, adjacent electrolyte units and metal units, or adjacent metal units are provided with steps that are mutually concave-convex nested and matched in the overlapping region.

9. The plasma enhanced chemical vapor deposition apparatus according to claim 7, wherein Adjacent sides of adjacent dielectric units, adjacent electrolyte units and metal units, or adjacent metal units are provided with mutually concave-convex nested and matched grooves and protrusions in the overlapping region.

10. The plasma enhanced chemical vapor deposition apparatus according to claim 1, wherein The gas distribution plate assembly, the upper electrode, the electrode shielding layer, and the lower electrode are all square.

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