Semiconductor device electrode and method of forming a protective layer therefor

Abstract

The application discloses a semiconductor device electrode and a preparation method of a protective layer thereof, and comprises a metal electrode and a HoFCVD device, wherein the metal electrode is covered with a protective layer on the surface by deposition with the HoFCVD device. The application utilizes silicon nitride or silicon oxynitride which has good weather resistance and chemical stability, and is covered on the electrode to play a role in isolating the moisture, ultraviolet rays, chemical reagents and the like in the external environment, thereby protecting the electrode. The silicon nitride or silicon oxynitride film layer has a reduction of reflection, and when specifically applied to a solar cell, the absorption capacity of the cell to sunlight can be improved, and the photoelectric conversion efficiency is improved. The TCO layer only plays a role in increasing the conductivity, and the thinning of the TCO can greatly reduce the manufacturing cost of the heterojunction solar cell. The application can be applied to the protection of most semiconductor device electrodes, and mass industrial production and large-scale application of the protective film layer can be realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor processing, in particular to a semiconductor device electrode and a preparation method of a protective layer thereof. BACKGROUND

[0002] The electrode of a semiconductor device is a bridge for physical and electrical connection between the device and an external circuit, and plays a role in controlling the inflow or outflow of current and applying a control voltage / signal to the device, and is an indispensable component of the semiconductor device. The electrode of a semiconductor device is usually made of a metal material, such as aluminum, copper, silver, nickel, etc., which utilizes the high conductivity of these metal materials to meet the functional requirements of the electrode for collecting electrons / holes and leading out the device.

[0003] As an interface between the inside and outside of a semiconductor device, these electrodes generally have poor weather resistance and are easily eroded by water vapor, acetic acid and other chemical reagents during long-term use. Once the metal electrode is eroded by the external environment, the performance of the electrode will be degraded, affecting the ability of the electrode to collect electrons / holes, and thus leading to a decrease in the performance of the semiconductor device and shortening its service life.

[0004] Currently, the protection of the electrode of a semiconductor device is mostly achieved by sputtering or coating a temporary protective layer on the surface of the metal electrode, and then etching, or by using the protective layer or shell during packaging to achieve simple physical protection of the metal electrode. For example, in the manufacturing process of a MEMS (Micro-Electro-Mechanical System) semiconductor device, a layer of aluminum (Al) is sputtered on the surface of the electrode (such as TiW / Au) as a temporary protective layer, and then the sacrificial layer is etched. After etching is completed, the aluminum layer is selectively removed with a phosphoric acid solution, so that the underlying electrode is not damaged. This method is complicated and requires the use of etching liquid, which can easily damage the semiconductor device. In the process of manufacturing a solar cell, after the metal grid lines of the cell sheet are manufactured, the glass, back plate, adhesive and aluminum frame used in the packaging process play a protective role for the metal electrode. This method does not specifically protect the metal electrode, but only uses glass, back plate, adhesive and aluminum frame as a protective layer, which is easily penetrated by water vapor and subjected to ultraviolet radiation in an environment with large changes in temperature and humidity, accelerating the aging of the protective layer and causing the metal electrode to be eroded, increasing the series resistance of the solar cell, and thus reducing the photoelectric conversion efficiency of the solar cell.

[0005] Therefore, we propose a semiconductor device electrode and a preparation method of a protective layer thereof to solve the problems raised in the background. SUMMARY

[0006] The purpose of the present application is to provide a semiconductor device electrode and a preparation method of a protective layer thereof to solve the problems raised in the background.

[0007] To achieve the above object, the present application provides the following technical solutions: a semiconductor device electrode, comprising: a metal electrode, a protective layer on the surface of the metal electrode being deposited by a HoFCVD device;

[0008] The protective layer on the connection part of the metal electrode and the external circuit is punched to make the metal electrode normally connected with the external circuit;

[0009] The protective layer is a protective film structure with optical regulation and weather resistance, which is made of silicon nitride or silicon oxynitride or a combination of both;

[0010] When the protective layer is made of silicon nitride or silicon oxynitride alone, it can be composed of multiple sub-layers.

[0011] Preferably, the thickness of the protective layer is 100-200 nm.

[0012] Preferably, the metal electrode is made of aluminum, copper, silver or nickel material.

[0013] Preferably, the metal electrode is fixedly arranged on the surface of a TCO layer, the TCO layer covers a P-type amorphous silicon layer, the P-type amorphous silicon layer covers an intrinsic amorphous silicon layer, and the intrinsic amorphous silicon layer covers a crystalline silicon substrate.

[0014] A protective layer preparation method for a semiconductor device electrode, the method being as follows:

[0015] S1, placing the semiconductor device with the completed metal electrode on a carrier plate, the metal electrode facing the hot wire direction;

[0016] S2, sending the carrier plate with the semiconductor device to a HoFCVD device, the HoFCVD device having an automatic feeding structure, a Load cavity, a heating cavity, a process cavity, an Unload cavity and an automatic unloading structure;

[0017] S3, depositing silicon nitride or silicon oxynitride in the process cavity by introducing H2, SiH4, NH3, O2 or H2, SiH4, NH3, N2O or H2, hexamethyldisilazane, NH3, N+O.

[0018] Preferably, the HoFCVD device controls the length of the hot wire so that the hot wire is distributed only in the area where the film needs to be plated, avoiding the deposition of film layers in the area where the film does not need to be plated.

[0019] Preferably, the HoFCVD device increases the surface area of the hot wire by increasing the diameter of the hot wire.

[0020] Preferably, the HoFCVD device increases the molecular pump pumping speed to maintain the ratio of the process cavity volume (L) to the molecular pump pumping speed (L / s) ≤0.25.

[0021] Preferably, the HoFCVD equipment is equipped with a cooling and heating system for the carrier plate and a temperature control device to intelligently control the temperature of the carrier plate and deposit a protective layer within the range of room temperature to 200°C.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] 1. Utilizing the excellent weather resistance and chemical stability of silicon nitride or silicon oxynitride, covering the electrodes can isolate them from the corrosion of external environment such as water vapor, ultraviolet rays, and chemical reagents, thus protecting the electrodes.

[0024] 2. Silicon nitride or silicon oxynitride films have anti-reflection properties. Specifically for solar cells, they can improve the cell's ability to absorb sunlight and increase photoelectric conversion efficiency. In addition, due to the design of the outermost silicon nitride or silicon oxynitride film, which acts as an anti-reflection layer, the TCO layer of heterojunction solar cells can be appropriately thinned, so that the TCO layer only plays the role of increasing conductivity. The thinning of the TCO layer will significantly reduce the manufacturing cost of heterojunction solar cells.

[0025] 3. Using HoFCVD coating technology, silicon nitride or silicon oxynitride films can be deposited on metal electrodes within the range of room temperature to 200℃, avoiding damage to semiconductor devices caused by high temperatures;

[0026] 4. By controlling the hot wire arrangement, hot wire selection, gas flow control, and maintaining the ratio of the equipment process chamber volume to the vacuum pumping speed, the above-mentioned optically modulated and weather-resistant film can be rapidly prepared at a speed of up to 4 nm / s.

[0027] 5. It can be applied to the electrode protection of most semiconductor devices, and the process is simple, does not require the use of etching solution, is safe and efficient. Combined with the coating principle of HoFCVD equipment and the control of key parameters of the equipment, the mass industrial production and large-scale application of this protective film can be realized. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention.

[0029] In the figure: 1. TCO layer; 2. P-type amorphous silicon layer; 3. Intrinsic amorphous silicon layer; 4. Crystalline silicon substrate; 5. Silver electrode; 6. Protective layer. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Please see Figure 1 The present invention provides a technical solution: a method for preparing a semiconductor device electrode and its protective layer, comprising: a metal electrode and a protective layer 6, wherein the protective layer 6 is deposited on the metal electrode, and holes are punched in the protective layer 6 at the connection points between the metal electrode and the external circuit to ensure normal communication between the metal electrode and the external circuit.

[0032] Protective layer 6 is a protective film structure with optical control and weather resistance, made of silicon nitride or silicon oxynitride or a combination of both.

[0033] The thickness of the protective layer 6 is 100-200nm, and the thickness of the anti-reflection protective layer 6 is preset according to the required thickness of the metal electrode 5 of the semiconductor device.

[0034] If the protective layer 6 is made of a single silicon nitride or silicon oxynitride, it can be composed of multiple sublayers.

[0035] Metal electrodes are commonly used electrodes in semiconductor devices and are made of materials such as aluminum, copper, silver, and nickel. In this embodiment, silver electrode 5 is used.

[0036] Silver electrode 5 is fixedly disposed on the surface of TCO layer 1. TCO layer 1 covers P-type amorphous silicon layer 2. P-type amorphous silicon layer 2 covers intrinsic amorphous silicon layer 3. Intrinsic amorphous silicon layer 3 covers crystalline silicon substrate 4.

[0037] During fabrication, the semiconductor device with the completed silver electrode 5 is placed on a carrier plate and then fed into a hot-wire CVD equipment for the deposition of the protective layer 6. After deposition, a laser is used to drill holes in the areas where welding is required. Then, the external circuit is connected to the silver electrode 5 at the drilled area to form a conductive path.

[0038] The specific steps for CVD deposition of protective layer 6 are as follows:

[0039] S1. Place the semiconductor device with the completed silver electrode 5 on the carrier plate, with the silver electrode 5 facing the hot wire direction.

[0040] S2. The carrier board holding the semiconductor devices is sent to the HoFCVD equipment. The HoFCVD equipment has automated loading, a Load chamber (a transition chamber connecting the atmosphere and the high vacuum chamber), a heating chamber (for heating the sample cell), a process chamber (for depositing a protective layer), an Unload chamber (a discharge chamber, a transition chamber connecting the atmosphere and the high vacuum chamber), and automated unloading.

[0041] S3. H2, SiH4, NH3, O2 or H2, SiH4, NH3, N2O or H2, hexamethyldisilazane (HMDS), NH3, N+O are introduced into the process chamber to deposit silicon nitride or silicon oxynitride.

[0042] To enable the HoFCVD equipment to produce the aforementioned protective layer 6 efficiently, quickly, and in large quantities, the following improvements were made to the HoFCVD equipment:

[0043] Increase the effective coating area by controlling the length of the hot wire so that the hot wire is distributed only in the area where coating is needed, thus avoiding the deposition of film in areas where coating is not needed.

[0044] Increasing the surface area of ​​the hot wire, by increasing the diameter of the hot wire, ensures that the process gas is completely decomposed, improves gas utilization, increases gas flow rate, and further improves the coating rate. However, if the surface area of ​​the hot wire increases to the point that its ability to decompose the process gas exceeds the amount of process gas introduced, the two become mismatched, wasting the hot wire's decomposition capacity. Therefore, it is necessary to further increase the gas flow rate.

[0045] Increasing the pumping speed of the molecular pump leads to increased gas flow and pressure, resulting in more side reactions that affect film deposition. Therefore, it is necessary to maintain the chamber gas pressure at a certain value, which necessitates increasing the pumping speed of the molecular pump.

[0046] Maintaining a process chamber volume (L) / molecular pump speed (L / s) ratio ≤0.25 allows for a coating speed ≥4nm / s. Keeping this ratio below 0.25 ensures sufficient process gas within the process chamber while closely matching the hot filament decomposition rate, thereby increasing the coating speed to as high as 4nm / s.

[0047] To reduce the impact of heat radiation from the hot wire on the uncontrollable substrate temperature, a cooling and heating system and a temperature control device are introduced through the carrier plate to implement intelligent temperature control of the carrier plate, thereby achieving the deposition of a protective layer 6 within the range of room temperature to 200℃.

[0048] Working principle: Covering the silver electrode 5 of the heterojunction cell with a protective layer 6 has the following functions: silicon nitride (SiNx) and silicon oxynitride (SiNxOy) have good weather resistance and chemical stability. Covering the silver electrode 5 can isolate it from the corrosion of water vapor, ultraviolet rays, chemical reagents and other external environments, thus protecting the metal electrode.

[0049] Silicon nitride (SiNx) and silicon oxynitride (SiNxOy) have excellent anti-reflection properties. When covered above the silver electrode 5, they can enhance light transmittance, increase the absorption of sunlight by the cell, and play an anti-reflection role. This allows for a suitable reduction in the thickness of the TCO layer 1 of the heterojunction cell, so that the original TCO layer 1 of the heterojunction cell only plays the role of increasing conductivity. The reduction of the TCO layer 1 will significantly reduce the manufacturing cost of heterojunction solar cells.

[0050] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

[0051] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a protective layer for an electrode of a semiconductor device, characterized in that, Includes the following steps: S1. Place the semiconductor device with the completed metal electrode fabrication onto the carrier plate, with the metal electrode facing the hot wire direction; S2. The carrier board on which the semiconductor devices are placed is sent to the HoFCVD equipment. The HoFCVD equipment has an automated feeding structure, a Load chamber, a heating chamber, a process chamber, an Unload chamber, and an automated unloading structure. S3. H2, SiH4, NH3, O2 or H2, SiH4, NH3, N2O or H2, hexamethyldisilazane, NH3, N+O are introduced into the process chamber to deposit silicon nitride or silicon oxynitride to form a protective layer on the metal electrode. The thickness of the protective layer is 100-200nm. The deposition temperature of the HoFCVD process chamber is from room temperature to 200°C, the deposition rate is 1–4 nm / s, the hot filament temperature is 1800–2200°C, and the HoFCVD equipment increases the molecular pump pumping speed to maintain the ratio of process chamber volume (L) / molecular pump pumping speed (L / s) ≤0.

25. The protective layer serves multiple functions, including electrode protection, optical anti-reflection, and allows for thinning of the transparent conductive oxide (TCO) layer. The protective layer has through holes at the metal electrode connection points to expose the metal electrodes for electrical connection.

2. The method for preparing a protective layer for a semiconductor device electrode according to claim 1, characterized in that, The HoFCVD device controls the length of the hot filament so that it is distributed only in the area where coating is required.

3. The method for preparing a protective layer for a semiconductor device electrode according to claim 1, characterized in that, The HoFCVD device increases the surface area of ​​the hot wire by increasing the diameter of the hot wire.

4. The method for preparing a protective layer for a semiconductor device electrode according to claim 1, characterized in that, The HoFCVD equipment is equipped with a cooling and heating system for the carrier plate, a temperature control device, and intelligent temperature control for the carrier plate.

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