Preparation method of microcrystalline silica film layer, heterojunction solar cell and preparation method of heterojunction solar cell

Abstract

The invention provides a preparation method of a microcrystalline silica film layer, a heterojunction solar cell and a preparation method of the heterojunction solar cell. The preparation method of the microcrystalline silicon oxygen film layer comprises the following steps: firstly, feeding a monocrystalline silicon wafer deposited with intrinsic amorphous silicon into a PECVD (Plasma Enhanced Chemical Vapor Deposition) process cavity, then vacuumizing the PECVD process cavity, stabilizing the pressure of the PECVD process cavity at 1-10 mbar, then adjusting the RF (Radio Frequency) power input into the PECVD process cavity to 2000-10000 W, setting the input RF frequency to be very high frequency, and controlling the pressure of the PECVD process cavity to be 1-10 mbar. The method comprises the following steps of: preparing a PECVD (Plasma Enhanced Chemical Vapor Deposition) process cavity, stabilizing the temperature of the PECVD process cavity at 160-230 DEG C, introducing process gas into the PECVD process cavity, enabling the process gas to comprise SiH4, H2, PH3 and CO2, enabling the volume ratio of the PH3 to the SiH4 to be 1%-10%, enabling the volume ratio of the CO2 to the SiH4 to be 20%-60%, and finally depositing a microcrystalline silicon oxygen film layer with a preset thickness on the intrinsic amorphous silicon surface of the monocrystalline silicon wafer after preset deposition time. According to the invention, the film forming quality of the microcrystalline silicon-oxygen film layer can be improved, and the dark attenuation phenomenon can be effectively improved.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic manufacturing, and in particular to a method for preparing a microcrystalline silicon oxygen film layer, a heterojunction solar cell and a method for preparing the same. Background Art

[0002] Heterojunction cells use microcrystalline silicon oxygen film as the cell window layer structure, which helps to increase the optical band gap of the microcrystalline N layer, enhance light transmittance, and improve the current and photoelectric conversion efficiency of the cell. At present, the industry usually uses very high frequency (including 27M, 40M and 60MHZ) to increase the deposition rate of microcrystalline N. The higher the frequency, the faster the electron oscillation, the higher the plasma concentration, and the faster the deposition rate. In the process of making microcrystalline silicon oxygen film, CO2 is usually used as a source of oxygen. Usually, as the CO2 flow rate increases, the light transmittance increases, and the cell efficiency increases. However, the increase in CO2 flow rate will cause the film to be less dense, with holes and defective states, and the film quality is poor, which is easily invaded by oxygen in the air or water vapor. The invasion of oxygen will cause the film performance to decay, thereby causing the photoelectric conversion efficiency of the heterojunction cell to decrease. This phenomenon of increasing efficiency decline over time is called dark decay.

[0003] Therefore, how to provide a method for preparing a microcrystalline silicon oxide film layer, a heterojunction solar cell and a preparation method thereof to improve the film formation quality of the microcrystalline silicon oxide film layer and effectively improve the dark decay phenomenon has become a technical problem that needs to be solved urgently in the industry. Summary of the invention

[0004] In view of the above problems in the prior art, the present invention proposes a method for preparing a microcrystalline silicon oxide film layer, which is characterized by comprising the following steps:

[0005] The single crystal silicon wafer on which the intrinsic amorphous silicon is deposited is fed into the PECVD process chamber;

[0006] The PECVD process chamber is evacuated and its pressure is stabilized at 1-10 mbar;

[0007] The RF power input into the PECVD process chamber is adjusted to 2000-10000 watts, and the input RF frequency is set to a very high frequency;

[0008] Stabilize the temperature of the PECVD process chamber at 160-230 degrees Celsius;

[0009] Introducing process gas into the PECVD process chamber, wherein the process gas includes SiH4, H2, PH3 and CO2, wherein the volume ratio of PH3 to SiH4 is 1%-10%, and the volume ratio of CO2 to SiH4 is 20%-60%; and

[0010] A microcrystalline silicon oxide film layer with a predetermined thickness is deposited on the intrinsic amorphous silicon surface of the single crystal silicon wafer over a predetermined deposition time.

[0011] In one embodiment, the ratio of O element to Si element in the microcrystalline silicon oxide film layer is 5-80%.

[0012] In one embodiment, the flow rate range of SiH4 in the process gas is 100 sccm-1000 sccm, the flow rate range of H2 is 20000 sccm-300000 sccm, the flow rate range of PH3 is 10 sccm-100 sccm, and the flow rate range of CO2 is 100 sccm-600 sccm.

[0013] In a more specific embodiment, the volume ratio of PH3 to SiH4 is 3%-8%, the volume ratio of CO2 to SiH4 is 30%-40%, and the volume ratio of H2 to SiH4 is 180-250.

[0014] In one embodiment, the pressure for depositing the microcrystalline silicon oxide film layer is 3-8 mbar, the predetermined deposition time is 100-400 seconds, the deposition temperature is 180-220 degrees Celsius, and the predetermined thickness is 10-30 nanometers.

[0015] In one embodiment, the deposition rate of the microcrystalline silicon oxide film layer is The crystallization rate of the microcrystalline silicon oxide film layer is between 20% and 60%.

[0016] In one embodiment, the very high frequency includes 27 MHZ, 40 MHZ and 60 MHZ.

[0017] In one embodiment, the microcrystalline silicon oxide film layer is deposited on the light incident side of the heterojunction solar cell made of the single crystal silicon wafer.

[0018] The present invention also provides a method for preparing a heterojunction solar cell, including a method for preparing the microcrystalline silicon oxygen film layer.

[0019] The present invention also provides a heterojunction solar cell, comprising a single crystal silicon wafer, and also comprising a first intrinsic amorphous silicon layer, a microcrystalline silicon oxide film layer, a first transparent conductive film and a first electrode formed in sequence on the light incident surface of the single crystal silicon wafer, and also comprising a second intrinsic amorphous silicon layer, a P-type microcrystalline silicon thin film layer, a second transparent conductive film and a second electrode formed in sequence on the backlight surface of the single crystal silicon wafer, characterized in that the microcrystalline silicon oxide film layer is formed by the above-mentioned method for preparing the microcrystalline silicon oxide film layer.

[0020] Compared with the prior art which uses very high frequency and has too high oxygen concentration, resulting in the presence of holes and defects in the microcrystalline silicon oxygen film layer, poor film quality and easy dark decay, the preparation method of the microcrystalline silicon oxygen film layer of the present invention first sends a single crystal silicon wafer deposited with intrinsic amorphous silicon into a PECVD process chamber, then evacuates the PECVD process chamber and stabilizes its pressure at 1-10 mbar, then adjusts the radio frequency (RF) power input into the PECVD process chamber to 2000-10000 watts, sets the input radio frequency (RF) frequency to very high frequency, then stabilizes the temperature of the PECVD process chamber at 160-230 degrees Celsius, then introduces process gas into the PECVD process chamber, the process gas includes SiH4, H2, PH3 and CO2, wherein the volume ratio of PH3 to SiH4 is 1%-10%, and the volume ratio of CO2 to SiH4 is 20%-60%, and finally deposits a microcrystalline silicon oxygen film layer of a predetermined thickness on the intrinsic amorphous silicon surface of the single crystal silicon wafer after a predetermined deposition time. The present invention can improve the film-forming quality of the microcrystalline silicon oxide film layer and effectively improve the dark decay phenomenon. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above features and advantages of the present invention can be better understood after reading the detailed description of the embodiments of the present disclosure in conjunction with the following drawings. In the drawings, the components are not necessarily drawn to scale, and components with similar related properties or features may have the same or similar reference numerals.

[0022] Figure 1 It is a schematic flow chart of the method for preparing the microcrystalline silicon oxide film layer of the present invention. DETAILED DESCRIPTION

[0023] The following specific embodiments illustrate the implementation of the present invention, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Although the description of the present invention will be introduced in conjunction with the preferred embodiment, this does not mean that the features of this invention are limited to this implementation. On the contrary, the purpose of introducing the invention in conjunction with the implementation is to cover other options or modifications that may be extended based on the claims of the present invention. In order to provide a deep understanding of the present invention, the following description will include many specific details. The present invention can also be implemented without using these details. In addition, in order to avoid confusion or blurring the focus of the present invention, some specific details will be omitted in the description.

[0024] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] In addition, the terms "upper", "lower", "left", "right", "top", "bottom", "horizontal" and "vertical" used in the following description should be understood as the directions shown in the paragraph and the related drawings. Such relative terms are only used for the convenience of description and do not mean that the device described therein must be manufactured or operated in a specific direction, and therefore should not be understood as limiting the present invention.

[0026] It is understood that although the terms "first", "second", "third", etc. may be used herein to describe various components, regions, layers and / or parts, these components, regions, layers and / or parts should not be limited by these terms, and these terms are only used to distinguish different components, regions, layers and / or parts. Therefore, the first component, region, layer and / or part discussed below may be referred to as a second component, region, layer and / or part without departing from some embodiments of the present invention.

[0027] See also Figure 1 , which is a schematic diagram of the process of preparing the microcrystalline silicon oxide film layer of the present invention. Figure 1 As shown, the method for preparing the microcrystalline silicon oxide film layer first performs step S100, where a single crystal silicon wafer deposited with intrinsic amorphous silicon is introduced into a PECVD process chamber.

[0028] Then proceed to step S110 to evacuate the PECVD process chamber and stabilize its pressure at 1-10 mbar.

[0029] Then proceed to step S120, adjust the RF power input to the PECVD process chamber to 2000-10000 watts, and set the input RF frequency to a very high frequency. The very high frequency includes 27 MHZ, 40 MHZ and 60 MHZ. In this embodiment, the very high frequency is 40 MHZ.

[0030] Then proceed to step S130 to stabilize the temperature of the PECVD process chamber at 160-230 degrees Celsius.

[0031] Then proceed to step S140, introducing process gas into the PECVD process chamber, wherein the process gas includes SiH4, H2, PH3 and CO2, wherein the volume ratio of PH3 to SiH4 is 1%-10%, and the volume ratio of CO2 to SiH4 is 20%-60%. The flow rate range of SiH4 in the process gas can be 100sccm-1000sccm, the flow rate range of H2 can be 20000sccm-300000sccm, the flow rate range of PH3 can be 10sccm-100sccm, and the flow rate range of CO2 can be 100sccm-600sccm. The volume ratio of PH3 to SiH4 can be 3%-8%, the volume ratio of CO2 to SiH4 can be 30%-40%, and the volume ratio of H2 to SiH4 is 180-250.

[0032] Then proceed to step S150, depositing a microcrystalline silicon oxide film layer of a predetermined thickness on the intrinsic amorphous silicon surface of the single crystal silicon wafer after a predetermined deposition time. The microcrystalline silicon oxide film layer is deposited on the light-incident side of the heterojunction solar cell made of the single crystal silicon wafer. The ratio of O element to Si element in the microcrystalline silicon oxide film layer is 5-80%. The pressure for depositing the microcrystalline silicon oxide film layer is 3-8 millibars (mbar), the predetermined deposition time is 100-400 seconds (s), the deposition temperature is 180-220 degrees Celsius (℃), and the predetermined thickness is 10-30 nanometers (nm). The deposition rate for depositing the microcrystalline silicon oxide film layer is The crystallization rate of the microcrystalline silicon oxide film layer is between 20% and 60%.

[0033] First embodiment:

[0034] The preparation method of the microcrystalline silicon oxide film layer in this embodiment firstly puts the single crystal silicon wafer deposited with intrinsic amorphous silicon into the PECVD process chamber; then evacuates the PECVD process chamber and stabilizes its pressure at 3-8 mbar; then adjusts the RF power input to the RF electrode in the PECVD process chamber to 5000-10000 watts, and sets the input RF frequency to 40 MHZ; then stabilizes the temperature of the PECVD process chamber at 200-220 degrees Celsius; then introduces process gas into the PECVD process chamber, the process gas includes SiH4, H2, PH3 and CO2, wherein the volume ratio of PH3 to SiH4 is 3%-8%, the volume ratio of CO2 to SiH4 is 30%, and the volume ratio of H2 to SiH4 is 20%. is 180-250, the flow rate range of SiH4 in the process gas is 500sccm-1000sccm, the flow rate range of H2 is 100000sccm-200000sccm, the flow rate range of PH3 is 50sccm-100sccm, and the flow rate range of CO2 is 150sccm-300sccm; finally, a microcrystalline silicon oxide film layer of a predetermined thickness is deposited on the intrinsic amorphous silicon surface of the single crystal silicon wafer after a predetermined deposition time, the ratio of O element to Si element in the microcrystalline silicon oxide film layer is 5-80%, the predetermined deposition time is 100-400 seconds, the deposition temperature is 200-220 degrees Celsius, the thickness of the deposited microcrystalline silicon oxide film layer is 20-30 nanometers, and the deposition speed of the deposited microcrystalline silicon oxide film layer is The crystallization rate of the microcrystalline silicon oxide film layer is between 20% and 60%.

[0035] The efficiency attenuation of the heterojunction solar cell formed by the first embodiment after being placed for 720 hours is only 0.2%, which is significantly improved compared with the efficiency attenuation of 0.7% of the heterojunction solar cell in the prior art after being placed for 720 hours.

[0036] Second embodiment:

[0037] The preparation method of the microcrystalline silicon oxide film layer in this embodiment firstly sends a single crystal silicon wafer deposited with intrinsic amorphous silicon into a PECVD process chamber; then the PECVD process chamber is evacuated and its pressure is stabilized at 3-8 mbar; then the radio frequency RF power input to the radio frequency electrode in the PECVD process chamber is adjusted to 5000-10000 watts, and the input radio frequency RF frequency is set to 40 MHZ; then the temperature of the PECVD process chamber is stabilized at 200-220 degrees Celsius; then process gas is introduced into the PECVD process chamber, and the process gas includes SiH4, H2, PH3 and CO2, wherein the volume ratio of PH3 to SiH4 is 3%-8%, the volume ratio of CO2 to SiH4 is 35%, and the volume ratio of H2 to SiH4 is 180-250, the flow rate range of SiH4 in the process gas is 500sccm-1000sccm, the flow rate range of H2 is 100000sccm-200000sccm, the flow rate range of PH3 is 50sccm-100sccm, and the flow rate range of CO2 is 175sccm-350sccm; then, a microcrystalline silicon oxide film layer of a predetermined thickness is deposited on the intrinsic amorphous silicon surface of the single crystal silicon wafer for a predetermined deposition time, the ratio of O element to Si element in the microcrystalline silicon oxide film layer is 5-80%, the predetermined deposition time is 100-400 seconds, the deposition temperature is 200-220 degrees Celsius, the thickness of the deposited microcrystalline silicon oxide film layer is 20-30 nanometers, and the deposition rate of the deposited microcrystalline silicon oxide film layer is 2- The crystallization rate of the microcrystalline silicon oxide film layer is between 20% and 60%.

[0038] The efficiency attenuation of the heterojunction solar cell formed by the second embodiment after being placed for 720 hours is only 0.3%, which is significantly improved compared with the efficiency attenuation of 0.7% of the heterojunction solar cell in the prior art after being placed for 720 hours.

[0039] The present invention also discloses a method for preparing a heterojunction solar cell, comprising: Figure 1 The preparation method of the microcrystalline silicon oxygen film layer.

[0040] The present invention further discloses a heterojunction solar cell, comprising a single crystal silicon wafer, a first intrinsic amorphous silicon layer, a microcrystalline silicon oxide film layer, a first transparent conductive film and a first electrode formed in sequence on a light incident surface of the single crystal silicon wafer, and a second intrinsic amorphous silicon layer, a P-type microcrystalline silicon thin film layer, a second transparent conductive film and a second electrode formed in sequence on a backlight surface of the single crystal silicon wafer, wherein the microcrystalline silicon oxide film layer is formed by Figure 1 The microcrystalline silicon oxide film layer is formed by the preparation method.

[0041] In summary, the preparation method of the microcrystalline silicon oxide film layer of the present invention firstly sends the single crystal silicon wafer deposited with intrinsic amorphous silicon into the PECVD process chamber, then evacuates the PECVD process chamber, and stabilizes its pressure at 1-10 mbar, then adjusts the RF power input into the PECVD process chamber to 2000-10000 watts, sets the input RF frequency to very high frequency, and then stabilizes the temperature of the PECVD process chamber at 160-230 degrees Celsius, and then introduces process gas into the PECVD process chamber, wherein the process gas includes SiH4, H2, PH3 and CO2, wherein the volume ratio of PH3 to SiH4 is 1%-10%, and the volume ratio of CO2 to SiH4 is 20%-60%, and finally deposits a microcrystalline silicon oxide film layer of a predetermined thickness on the intrinsic amorphous silicon surface of the single crystal silicon wafer after a predetermined deposition time. The present invention can improve the film quality of the microcrystalline silicon oxide film layer and effectively improve the dark decay phenomenon.

[0042] The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be apparent to those skilled in the art, and the universal principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein, but should be granted the widest scope consistent with the principles and novel features disclosed herein. The above embodiments are provided to persons familiar with the art to implement or use the present invention, and persons familiar with the art may make various modifications or changes to the above embodiments without departing from the inventive concept of the present invention, and thus the scope of protection of the present invention is not limited by the above embodiments, but should be the maximum scope of the innovative features mentioned in the claims.

Claims

1. A method for preparing a microcrystalline silicon oxide film layer, characterized in that: The following steps are involved: The single crystal silicon wafer deposited with intrinsic amorphous silicon is fed into a PECVD process chamber; The PECVD process chamber is evacuated and its pressure is stabilized at 1-10 mbar; The RF power input into the PECVD process chamber is adjusted to 2000-10000 watts, and the RF frequency input is set to a very high frequency; Stabilize the temperature of the PECVD process chamber at 160-230 degrees Celsius; Introducing process gas into the PECVD process chamber, wherein the process gas includes SiH4, H2, PH3 and CO2, wherein the volume ratio of PH3 to SiH4 is 1%-10%, and the volume ratio of CO2 to SiH4 is 20%-60%; as well as A microcrystalline silicon oxide film layer with a predetermined thickness is deposited on the intrinsic amorphous silicon surface of the single crystal silicon wafer over a predetermined deposition time.

2. The method for preparing a microcrystalline silicon oxide film layer according to claim 1, characterized in that: The ratio of O element to Si element in the microcrystalline silicon oxide film layer is 5-80%.

3. The method for preparing a microcrystalline silicon oxide film layer according to claim 1 or 2, characterized in that: The flow range of SiH4 in the process gas is 100sccm-1000sccm, the flow range of H2 is 20000sccm-300000sccm, the flow range of PH3 is 10sccm-100sccm, and the flow range of CO2 is 100sccm-600sccm.

4. The method for preparing a microcrystalline silicon oxide film layer according to claim 3, characterized in that: The volume ratio of PH3 to SiH4 is 3%-8%, the volume ratio of CO2 to SiH4 is 30%-40%, and the volume ratio of H2 to SiH4 is 180-250.

5. The method for preparing a microcrystalline silicon oxide film layer according to claim 3 or 4, characterized in that: The pressure for depositing the microcrystalline silicon oxygen film layer is 3-8 mbar, the predetermined deposition time is 100-400 seconds, the deposition temperature is 180-220 degrees Celsius, and the predetermined thickness is 10-30 nanometers.

6. The method for preparing a microcrystalline silicon oxide film layer according to claim 3 or 4, characterized in that: The deposition rate of the microcrystalline silicon oxide film layer is The crystallization rate of the microcrystalline silicon oxide film layer is between 20% and 60%.

7. The method for preparing a microcrystalline silicon oxide film layer according to claim 3 or 4, characterized in that: The very high frequency includes 27MHZ, 40MHZ and 60MHZ.

8. The method for preparing a microcrystalline silicon oxide film layer according to claim 1 or 2, characterized in that: The microcrystalline silicon oxygen film layer is deposited on the light incident side of the heterojunction solar cell made of the single crystal silicon wafer.

9. A method for preparing a heterojunction solar cell, characterized in that: A method for preparing a microcrystalline silicon oxide film layer comprising the steps of any one of claims 1 to 8.

10. A heterojunction solar cell, comprising a single crystal silicon wafer, and further comprising a first intrinsic amorphous silicon layer, a microcrystalline silicon oxide film layer, a first transparent conductive film and a first electrode formed in sequence on a light incident surface of the single crystal silicon wafer, and further comprising a second intrinsic amorphous silicon layer, a P-type microcrystalline silicon thin film layer, a second transparent conductive film and a second electrode formed in sequence on a backlight surface of the single crystal silicon wafer, characterized in that: The microcrystalline silicon oxide film layer is formed by the method for preparing a microcrystalline silicon oxide film layer according to any one of claims 1 to 8.

Images