Method for reducing particles in furnace tube of chemical vapor deposition technology

Abstract

The invention discloses a method for reducing particles in furnace tube of a chemical vapor deposition technology. In the cooling step after the film forming process of the chemical vapor deposition technology, a circulation purifying technology is adopted to process the furnace tube, nitrogen gas and nitrous oxide are introduced into the furnace tube at the same time, thus the DCS (dichlorosilane, SiH2Cl2), which is attached to the wall of the gas discharging pipe in the film forming process, carries out reactions with the nitrous oxide, the DCS is converted into an oxidation layer, and finally the oxidation layer is discharged out of the system from the gas discharging pipe; wherein the circulation purifying technology specifically comprises the following steps: reducing the pressure in the furnace tube to a base pressure, simultaneously introducing nitrogen gas and nitrous oxide into the furnace tube, maintaining the pressure for a while, then reducing the pressure in the furnace tube to a base pressure for another time, then simultaneously introducing nitrogen gas and nitrous oxide into the furnace tube for another time, maintaining for a while, reducing for the pressure in the furnace tube to a base pressure again, and circularly repeating the processes mentioned above. The method can reduce the particles in furnace tube of the chemical vapor deposition technology, and at the same time the operation period of the technology and equipment output are not influenced.

Description

technical field [0001] The invention belongs to a manufacturing process method of a semiconductor integrated circuit, in particular to a chemical vapor deposition furnace tube process, in particular to a method for improving chemical vapor deposition furnace tube process particles. Background technique [0002] The nitrogen oxide layer and oxide layer in the traditional chemical vapor deposition furnace tube process are usually formed by using excess gas (NH 3 Ammonia or N 2 O laughing gas), so as to avoid the increase of particles caused by film formation. However, more and more existing processes need to utilize the characteristics of the silicon-rich process, which can not only increase the etch barrier capability but also greatly increase the charge storage capacity in the SONOS flash memory device process, and ultimately greatly increase the sassafras, write window. However, the introduction of rich silicon has brought serious particle problems, more than doubling th...

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Problems solved by technology

However, more and more existing processes need to utilize the characteristics of the silicon-rich process, which can not only increase the etch barrier capability but also greatly increase the charge storage capacity in the SONOS flash memory device process, and ultimately greatly increase the sassafras, write window

However, the introduction of rich silicon has brought serious particle problems, which more than doubles the maintenance frequency of furnace tubes, and even causes damage to the exhaust stack valve of low-pressure equipment in processes with high silicon content.

[0003] The main reason for the series of problems caused by the analysis of silicon-rich process phenomena is that the flow rate of DCS (dichlorodihydrosilane) has been greatly improved in the process, making it relatively NH 3 The proportion of (ammonia) has increased a lot, resulting in the fact that DCS (dichlorodihydrosilane) cannot be completely reacted during the actual film formation, and a large amount of residual gas needs to be pumped away

However, the high-temperature DCS (dichlorodihydrogensilane) gas is very easy to adhere to the exhaust pipe opening and the pipe of the furnace tube after rapid cooling, making it impossible to clean it completely

Therefore, after a long period of accumulation, there will be more serious particle problems

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