A process for depositing silicon nitride by tubular PECVD

Abstract

The invention discloses a tubular type silicon nitride PECVD technology. Film plating is carried out twice, the temperature used for plating a first film is lower than the temperature used for plating a second film. The deposition technology provided by the invention improves the passivation anti-reflection effect of a tubular type PECVD silicon nitride film for a crystal silicon solar battery and reduces technology time.

Description

technical field [0001] The invention belongs to the technical field of photovoltaics, and in particular relates to a process for depositing silicon nitride by tubular PECVD. Background technique [0002] SiN x The film has the function of passivating the surface of the silicon wafer and anti-reflection. In the traditional preparation process of crystalline silicon solar cells, a layer of SiN is deposited on the surface of the emitter by plasma enhanced chemical vapor deposition (PECVD). x Thin films are a very important step in this. [0003] PECVD uses microwave or radio frequency to ionize the gas containing the constituent atoms of the film to form plasma locally, and the plasma is highly chemically active and easy to react, depositing the desired film on the substrate. In order to enable the chemical reaction to proceed at a lower temperature, the activity of the plasma is used to promote the reaction, so this CVD is called plasma-enhanced chemical vapor deposition (PE...

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Problems solved by technology

[0004] However, using this method to prepare SiN x film, when the temperature is low, there is a large amount of undecomposed metastable SiH in the film x , this molecule will affect the passivation characteristics of the surface; and this part of Si-H is fully decomposed when deposited at 400 ° C, and the passivation level is improved

When the temperature rises above 450°C, more hydrogen molecules will be released from the film, resulting in poor hydrogen passivation effect.

When the coating temperature is low, the coating time will be longer. At the same time, the graphite boat is easy to be heated unevenly during the coating process of the twenty-one graphite boat, resulting in chromatic aberration.

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