CN102903626A - Silicon nitride coating method with silicon wafer surface cleaning function - Google Patents

Abstract

The invention relates to manufacture of crystalline silicon solar cells, in particular to a nitride coating method with a silicon wafer surface cleaning function. The nitride coating method comprises the steps of: when a silicon wafer is subjected to silicon nitride coating on a silicon nitride coating device, after the silicon wafer enters a reaction cavity, before a silicon nitride deposition is carried out, introducing cleaning gases NH3, N2 and Ar into the reaction cavity, opening an original radio frequency power supply of the silicon nitride coating device, under a reaction temperature capable of generating plasma, carrying out chemical and physical functions on the surface of the silicon wafer by active radials and charged particles in the plasma for cleaning pollutant residues on the surface of the silicon wafer; and then carrying out conventional silicon nitride deposition. The nitride coating method can be used for eliminating idler wheel mark pollution on the surface of the silicon wafer in a silicon nitride coating process, and is simple and convenient for operation.

Description

Silicon nitride film plating process with silicon wafer surface cleaning function

Technical field

The present invention relates to the manufacturing of crystal silicon solar energy battery, specifically a kind of silicon nitride film plating process with silicon wafer surface cleaning function.

Background technology

In the crystal silicon solar cell sheet production process, cleaning is a vital technique.Chain type wet clean process (making herbs into wool or etching technics) is used more universal in crystal silicon battery is produced at present.Adopt the chain type wet clean process, silicon chip in the end all has the step of oven dry the residual water on cell piece surface is removed.What generally adopt at present is with hot blast cutter oven dry silicon chip, in order to make silicon chip keep balance, has on the equipment up and down that roller clamps silicon chip when adopting hot blast cutter oven dry silicon chip, is offset even beats to guarantee that silicon chip can not produce under compressed-air actuated effect.Such design no doubt can guarantee that silicon chip can not occur to be offset or to beat in transmission process, but because there is roller contact in the cell piece front, when oven dry, stay easily the trace of roller contact, these materials of staying silicon chip surface contain the impurity of acid solution the inside in the cleaning process, the impurity such as the release material on the roller.This trace can present macroscopic rolling wheel stamp behind the silicon nitride plated film, it is more clear that this rolling wheel stamp can become behind sintering.The existence of rolling wheel stamp has had a strong impact on the outward appearance of cell piece, causes the reduction of cell piece outward appearance yield.At present oven dry place is not because the rolling wheel stamp that roller contact causes also has effective measure to eliminate.Increase the maintenance frequency of roller or shortening and change the liquid cycle and can reduce the probability that rolling wheel stamp produces, but can't thoroughly eliminate, and increase the maintenance frequency or shortening and change the liquid cycle and also can cause the rising of production cost.

Summary of the invention

The present invention wants the technical solution problem to be, silicon nitride film plating process to traditional silicon chip improves, provide a kind of silicon chip surface rolling wheel stamp of can in the silicon nitride coating process, eliminating to pollute the simple, convenient silicon nitride film plating process with silicon wafer surface cleaning function.

Silicon nitride film plating process with silicon wafer surface cleaning function of the present invention is: when on the silicon nitride filming equipment silicon chip being carried out the silicon nitride plated film, after silicon chip enters reaction cavity, before not carrying out silicon nitride deposition step, first be filled with purge gas NH3, N2, Ar to reaction cavity, open the original radio-frequency power supply of silicon nitride filming equipment, under the reaction temperature that can produce plasma, living radical in the plasma and charged particle carry out the effect of chemistry and physics, cleaning silicon chip surface contamination residue to silicon chip surface; Then, carry out conventional silicon nitride deposition.

Specifically may further comprise the steps:

Step 1, preheating, the reaction cavity that silicon chip enters the silicon nitride filming equipment carries out first constant temperature, reaches the reaction temperature of setting, and the Temperature Setting scope is 350～450 ℃;

Step 2, a constant voltage is filled with purge gas NH3, N2, Ar to reaction cavity, NH3 flow 2000～4000 sccm/min, N2 flow 10000～20000 sccm/min, Ar flow 1000～10000 sccm/min, pressure limit 0.5～1.5Torr;

Step 3, clean, radio-frequency power supply is opened, radio-frequency power scope 5000～15000W, under reaction temperature, the living radical in the plasma and charged particle carry out the effect of chemistry and physics, cleaning silicon chip surface contamination residue to silicon chip surface, scavenging period is decided on the dirty situation of silicon chip surface and production capacity, is generally 10～1200s;

Step 4 is found time, and will clean residual gas extraction chamber, for follow-up silicon nitride deposition is prepared;

Step 5, secondary constant voltage and SiN deposit pass into the required gas of silicon nitride deposition (such as NH3, SiH4, N2 etc.) and reach pressure constant state, radio-frequency power supply are opened, according to the silicon nitride deposition method generation silicon nitride film of routine.

The present invention passes through to increase by one in former silicon nitride deposition processing step and cleans link, can carry out first in original silicon nitride equipment the inside the clean on surface to silicon chip surface, automatically carries out follow-up silicon nitride deposition after cleaning is finished.All cleaning steps can be embedded in former silicon nitride deposition technological parameter the inside, form the complete silicon nitride deposition technique with Wafer Cleaning function.After adopting the inventive method, effectively eliminated the rolling wheel stamp that stays after the wet-cleaned, the silicon chip outward appearance is good behind the plated film, through also occurring without cleaning residual rolling wheel stamp behind the high temperature sintering.

Embodiment

Embodiment one:

Step 1 passes into N2 in the reactor of flat direct method silicon nitride filming equipment and makes silicon chip reach constant temperature, N2 range of flow 15000sccm/min; Temperature is 400 ℃ (it is consistent with this step that the following steps temperature all keeps);

Step 2 passes into purge gas NH3, N2, Ar, and the NH3 flow is 3000sccm/min, and the N2 flow is 15000sccm/min, and the Ar flow is 5000sccm/min, and controlled pressure is 1Torr;

Step 3 is opened radio-frequency power supply and is carried out the surface plasma cleaning, and radio-frequency power is 8000W, and the time is that the too short cleaning performance of 50s(is bad, the oversize production capacity that affects);

Step 4 is then closed radio-frequency power supply, and erase residual gas is extracted out, and the time be〉but 10s(such as production capacity without affecting proper extension);

Step B5 passes into silicon nitride deposition gas, and the NH3 flow is 550sccm/min, and the SiH4 flow is 1700sccm/min, N2 flow 2200sccm/min, and reaching constant voltage is 1Torr; Open radio-frequency power supply, radio-frequency power is 10000W, and the time is 66s; Carry out the silicon nitride film deposit.

Embodiment two:

Step 1 passes into N2 in the reactor of flat direct method silicon nitride filming equipment and makes silicon chip reach constant temperature, N2 range of flow 20000sccm/min; Temperature is 400 ℃ (it is consistent with this step that the following steps temperature all keeps);

Step 2 passes into purge gas NH3, N2, Ar, and the NH3 flow is 2500sccm/min, and the N2 flow is 20000sccm/min, and the Ar flow is 5000sccm/min, and controlled pressure is 1.5Torr;

Step 3 is opened radio-frequency power supply and is carried out the surface plasma cleaning, and radio-frequency power is 6000W, and the time is that the too short cleaning performance of 40s(is bad, the oversize production capacity that affects);

Step 4 is then closed radio-frequency power supply, and erase residual gas is extracted out, and the time be〉but 10s(such as production capacity without affecting proper extension);

Step 5 passes into silicon nitride deposition gas, and the NH3 flow is 550sccm/min, and the SiH4 flow is 1700sccm/min, N2 flow 2200sccm/min, and reaching constant voltage is 1Torr; Open radio-frequency power supply, radio-frequency power is 10000W, and the time is 66s; Carry out the silicon nitride film deposit.

Silicon chip product appearance behind the plated film that above-described embodiment obtains is good, through also occurring without cleaning residual rolling wheel stamp behind the high temperature sintering.

Claims (2)

1. silicon nitride film plating process with silicon wafer surface cleaning function, it is characterized in that: when on the silicon nitride filming equipment, silicon chip being carried out the silicon nitride plated film, after silicon chip enters reaction cavity, before not carrying out silicon nitride deposition step, first be filled with purge gas NH3, N2, Ar to reaction cavity, open the original radio-frequency power supply of silicon nitride filming equipment, under the reaction temperature that can produce plasma, living radical in the plasma and charged particle carry out the effect of chemistry and physics, cleaning silicon chip surface contamination residue to silicon chip surface; Then, carry out conventional silicon nitride deposition.

2. the silicon nitride film plating process with silicon wafer surface cleaning function according to claim 1 is characterized in that: its concrete steps are,

Step 1, preheating, the reaction cavity that silicon chip enters the silicon nitride filming equipment carries out first constant temperature, reaches the reaction temperature of setting, and the Temperature Setting scope is 350～450 ℃;

Step 2, a constant voltage is filled with purge gas NH3, N2, Ar to reaction cavity, NH3 flow 2000～4000 sccm/min, N2 flow 10000～20000 sccm/min, Ar flow 1000～10000 sccm/min, pressure limit 0.5～1.5Torr;

Step 3, clean, radio-frequency power supply is opened, radio-frequency power scope 5000～15000W, under reaction temperature, the living radical in the plasma and charged particle carry out the effect of chemistry and physics, cleaning silicon chip surface contamination residue to silicon chip surface, scavenging period is decided on the dirty situation of silicon chip surface and production capacity, is generally 10～1200s;

Step 4 is found time, and will clean residual gas extraction chamber, for follow-up silicon nitride deposition is prepared;

Step 5, secondary constant voltage and SiN deposit pass into the required gas of silicon nitride deposition (such as NH3, SiH4, N2 etc.) and reach pressure constant state, radio-frequency power supply are opened, according to the silicon nitride deposition method generation silicon nitride film of routine.