Hot wire surface treatment method and hot wire

Abstract

The invention provides a hot wire surface treatment method and a hot wire, and relates to the technical field of hot wire CVD. According to the surface treatment method provided by the invention, after the metal nitride layer is formed by nitriding the surface of the hot wire, the diffusion growth rate of the silicification layer on the surface of the hot wire can be delayed when the hot wire is subjected to silicon film deposition, so that the working life of the hot wire is effectively prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of CVD hot wires, and in particular to a hot wire surface treatment method and the hot wire. Background Art

[0002] Hot wire chemical vapor deposition equipment (hot wire CVD) is an advanced equipment used to prepare thin film materials. During operation, the hot wire is heated to 1600-1800℃ to catalytically crack the reaction gas on the surface of the hot wire and nearby. The generated active groups are deposited and grown on the substrate to form a thin film. Hot wire CVD is widely used in the field of solar cells and semiconductors, and can be used to prepare silicon thin film materials such as amorphous silicon and microcrystalline silicon. Compared with plasma enhanced chemical vapor deposition (PECVD) equipment, hot wire CVD equipment has lower cost, higher production capacity, and better coating quality. It has the prospect of replacing PECVD for amorphous silicon / crystalline silicon heterojunction (HJT) solar cells; and because of its low-temperature growth characteristics, it can be well used for the growth of anti-reflection passivation films on the surface of back-contact HJT cells.

[0003] The hot wire used in the hot wire CVD equipment is mainly a metal wire with a high melting point, such as tungsten, tantalum, molybdenum and their alloy materials, so that the hot wire can maintain its own structural stability when heated to 1600-1800°C. However, when using the hot wire to deposit and grow silicon film, the silicon-containing gas easily reacts with the surface of the hot wire at high temperature to form a metal silicide layer, and under high-temperature diffusion conditions, the metal silicide layer continues to diffuse into the hot wire, causing the metal silicide layer to continue to thicken, consuming the hot wire metal until it breaks brittlely.

[0004] Therefore, the hot wire is a consumable in the hot wire CVD equipment. The hot wire has a limited service life during the hot wire CVD production operation, and the hot wire must be replaced regularly. Each replacement not only causes the consumption of hot wire materials, but also causes the production process of the production line to stagnate during the replacement process. Therefore, it is urgent to provide a solution to extend the service life of the hot wire. Summary of the invention

[0005] The object of the present invention is to provide a hot wire surface treatment method and a hot wire, by nitriding the surface of the hot wire to form a protective metal nitride layer, so as to slow down the diffusion growth rate of the silicide layer on the surface of the hot wire when the silicon film is deposited, thereby effectively improving the working life of the hot wire.

[0006] In a first aspect, the present invention provides a method for treating the surface of a hot wire, wherein the surface of the hot wire is nitrided; the hot wire is a metal wire having a melting point greater than or equal to 2000°C.

[0007] The hot wire surface treatment method provided by the present invention can in-situ grow a layer of hot wire metal nitride protection film on the hot wire surface after nitriding the hot wire surface, thereby inhibiting the surface silicide of the hot wire material in a silicon-containing atmosphere, thereby greatly extending the working life of the hot wire.

[0008] Optionally, the hot wire is subjected to a high temperature nitridation treatment in a nitrogen-containing atmosphere.

[0009] Optionally, the hot wire is heated to 1100-1600° C. in a nitrogen atmosphere to perform a nitridation treatment.

[0010] Optionally, the hot wire is subjected to a high-temperature nitridation treatment in a nitrogen-containing atmosphere of 5-100 Pa.

[0011] Optionally, the nitrogen-containing atmosphere includes one of nitrogen and ammonia.

[0012] Optionally, the material of the heating wire includes one of metal tantalum, metal tungsten, metal molybdenum and alloys thereof.

[0013] Optionally, the diameter of the hot wire is 0.5-1.5 mm.

[0014] Optionally, the surface of the hot wire is subjected to nitriding treatment for 10-100 minutes.

[0015] In a second aspect, the present invention further provides a heating wire produced by any of the above-mentioned optional surface treatment methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a scanning electron microscope image of the cross section of the hot wire after the hot wire is treated in Example 1 of the present invention after the accelerated silicide aging treatment;

[0017] Figure 2 This is a scanning electron microscope picture of the cross section of the blank example hot wire of the present invention after accelerated siliconization aging treatment. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be the common meanings understood by people with general skills in the field to which the present invention belongs.

[0019] The present invention provides a method for treating the surface of a hot wire, wherein a hot wire metal nitride layer is formed on the surface of the hot wire by nitriding the surface of the hot wire, thereby protecting the hot wire and delaying the silicide of the metal surface of the hot wire. Specifically, the hot wire used can be a hot wire that has been used for a period of time in a hot wire CVD device and has not reached the replacement requirement, or it can be a newly purchased and unused hot wire.

[0020] Specifically, when the hot wire is nitrided, the nitrogen-containing atmosphere used includes one of nitrogen and ammonia. In fact, nitrogen and ammonia on the hot wire surface and nearby at 1100-1600°C can catalytically decompose to produce active nitrogen atoms, and there are no other impurity elements, which can prevent impurity elements from entering the hot wire and affecting the formation of the nitride layer.

[0021] Specifically, when the hot wire is subjected to surface nitridation treatment, the hot wire to be nitrided can be installed in the hot wire CVD device in advance, and the hot wire is subjected to nitridation treatment in advance before the subsequent silicon film deposition operation. In this way, the continuity of the use of the hot wire CVD device can be improved, and the need to use additional equipment to perform surface treatment on the hot wire is avoided, thereby improving the convenience of use of the treatment method provided by the present invention.

[0022] In some embodiments, when the surface of the hot wire is subjected to nitridation treatment, the hot wire is subjected to high-temperature nitridation treatment in a nitrogen-containing atmosphere of 5-100Pa. By performing the treatment in a low-pressure environment, the activity of active nitrogen atoms produced by cracking can be increased, and the nitrogen atoms can be promoted to diffuse to the surface of the hot wire. At the same time, the low-pressure environment can also help the nitrogen-containing atmosphere to be evenly distributed around the hot wire, thereby improving the uniformity of the generated hot wire metal nitride layer and reducing the incorporation of impurities.

[0023] Specifically, the present invention also provides a hot wire obtained by surface treatment according to any of the above embodiments, which includes a hot wire substrate and a hot wire metal nitride layer infiltration-formed on the surface of the hot wire substrate. The hot wire metal nitride layer can effectively delay the penetration of silicon atoms on the surface of the hot wire, thereby increasing the service life of the hot wire.

[0024] In fact, when the hot wire with the surface nitrided is installed in the hot wire CVD equipment to grow amorphous silicon film at 1600-1800°C, the hot wire metal nitride layer on the surface of the hot wire has good stability and will not decompose to pollute the amorphous silicon film.

[0025] Example 1

[0026] This embodiment 1 provides a hot wire surface treatment method, comprising the following steps:

[0027] S1. Use a pure tantalum wire with a diameter of 1 mm as the hot wire to be nitrided, and install it in the equipment chamber of the hot wire CVD. After exhausting the equipment chamber, introduce pure ammonia as the nitrogen-containing gas, and control the pressure in the equipment chamber to be 10Pa;

[0028] S2. Start the hot wire CVD equipment and supply power to the hot wire, so that the surface temperature of the hot wire rises to 1200° C. and keeps the temperature for 60 minutes, then cools to room temperature and takes out the hot wire after surface nitriding treatment.

[0029] Example 2 to Example 4

[0030] Embodiments 2 to 4 provide a hot wire surface treatment method, which differs from Embodiment 1 in the type of nitrogen-containing gas, pressure, hot wire temperature, and insulation time, as shown in Table 1 below.

[0031] Table 1 Type, pressure, heating wire temperature and insulation time of nitrogen-containing gas in Examples 1 to 4

[0032] Nitrogen-containing gas Pressure / Pa Heating wire temperature / ℃ Insulation time / min Example 1 Pure Ammonia 10 1200 60 Example 2 Pure Nitrogen 80 1200 60 Example 3 Pure Ammonia 20 1500 30 Example 4 Pure Ammonia 8 1400 40

[0033] Performance Testing

[0034] A pure tantalum wire with a diameter of 1 mm was used as a blank example, and an accelerated silicidation aging test was carried out with the hot wires prepared in Examples 1 to 4, including: the hot wires were respectively installed in hot wire CVD equipment of the same specifications and models, and after aging treatment for 5 hours at a silane pressure of 10 Pa (10 times the conventional HJT solar cell amorphous thin film growth conditions) and a hot wire temperature of 1700°C, the weight gain of the hot wire before and after the aging test was weighed, and the weight gain of the hot wire was divided by the total surface area of ​​the hot wire to calculate the weight gain per unit surface area of ​​the hot wire after the accelerated silicidation aging test, which was used as an indicator to measure the degree of silicidation of the hot wire. The results are shown in Table 2 below.

[0035] The hot wire treated in Example 1 and the hot wire in the blank example were cross-sectioned and scanned by a scanning electron microscope. Figure 1 and Figure 2 shown.

[0036] Table 2 Accelerated siliconization aging test results

[0037] <![CDATA[Weight gain per unit surface area / mg·cm 2 > Example 1 2.1 Example 2 2.6 Example 3 2.8 Example 4 2.1 Blank example 5.5

[0038] from Figure 1 and Figure 2 It can be seen that Figure 1 The thickness of the tantalum silicide layer in Figure 2This indicates that the present invention can inhibit the silicification penetration ability of the hot wire surface during long-term use by nitriding the hot wire surface. At the same time, the data in Table 2 also show that the weight gain of the hot wire with nitrided surface after the present invention is significantly less than that of the blank after accelerated aging, which indicates that it is difficult for silicon element to penetrate into the hot wire, and the surface silicification of the hot wire is significantly inhibited. Compared with the blank, the degree of silicification is reduced by 50-60%.

[0039] Although the embodiments of the present invention are described in detail above, it is obvious to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations are within the scope and spirit of the present invention as described in the claims. Moreover, the present invention described herein may have other embodiments and may be implemented or realized in a variety of ways.

Claims

1. A hot wire surface treatment method, characterized in that: The surface of the hot wire is nitrided; the hot wire is a metal wire with a melting point greater than or equal to 2000°C.

2. The hot wire surface treatment method according to claim 1, characterized in that: The hot wire is subjected to high temperature nitriding treatment in a nitrogen-containing atmosphere.

3. The hot wire surface treatment method according to claim 2, characterized in that: The hot wire is heated to 1100-1600°C in a nitrogen atmosphere for nitriding treatment.

4. The hot wire surface treatment method according to claim 2, characterized in that: The hot wire is subjected to high temperature nitriding treatment in a nitrogen atmosphere of 5-100Pa.

5. The hot wire surface treatment method according to any one of claims 2 to 4, characterized in that: The nitrogen-containing atmosphere includes one of nitrogen and ammonia.

6. The hot wire surface treatment method according to claim 1, characterized in that: The material of the heating wire includes one of metal tantalum, metal tungsten, metal molybdenum and alloys thereof.

7. The hot wire surface treatment method according to claim 1 or 6, characterized in that: The diameter of the hot wire is 0.5-1.5 mm.

8. The hot wire surface treatment method according to claim 1, characterized in that: The surface of the hot wire is nitrided for 10-100 minutes.

9. A hot wire obtained by the surface treatment method according to any one of claims 1 to 8, characterized in that: The heating wire comprises a heating wire substrate and a heating wire metal nitride layer infiltrated on the surface of the heating wire substrate.

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