Based On Mass Flow Control Design Of Multi-channel Gas Distributor

In the process of chip manufacturing,the standard gas composed of a single component gas mixed according to a specific concentration is widely used in film deposition,etching,passivation and other processes.The concentration of standard gas will directly affect the yield of chip components.It can be said that the concentration determines the result of chip production.For example,during ion implantation,if the mixing ratio of standard gas is deviated,the PN junction concentration of silicon wafer will not reach the standard value,resulting in electrical drift.Moreover,in the deposition process,if the standard gas used for deposition contains impurities,conductive ions will appear on the surface of the insulating layer,resulting in short circuit.Therefore,it is very important to ensure standard gas accuracy for chip production process.At present,the standard gas configuration has weighing method and partial pressure method and mass flow method.Weighing method is a reliable method for preparing gas reference materials.However,it is only suitable for the configuration of a single component of standard gas,which cannot meet the production needs of the chip manufacturing industry.Partial pressure method can meet the needs of general measurement,but its accuracy can not reach the international standard,the current weighing method and partial pressure method are obviously not suitable for the production needs of the industry.In order to realize the high precision configuration of multi-channel input standard gas,the research is mainly done from the aspect of gas flow measurement.Through the accurate measurement of gas flow to adjust the valve opening and then adjust the gas velocity and finally get the required gas concentration.In view of the influence of the temperature of the hot gas on the measurement accuracy of the gas flow when the configuration,this design is based on the hot mass flowmeter,based on the analysis of the hot gas mass flow measurement principle,design based on the mass flow control temperature compensation sensor flow control system.The probe characteristics of different temperature and current are investigated by using the designed hot film probe,and the relationship between the optimal current temperature compensation resistance and the measuring resistance is obtained,which provides support for the subsequent flow measurement circuit design.In order to reduce the interference of noise in the sampling process,the weighted data fusion algorithm was used and compared with the mean filtering algorithm,and the error analysis effect diagram was established.The experimental results show that the gas flow measurement error based on the weighted data fusion processing algorithm is less than 0.4 %,which has a higher measurement accuracy and realizes the accurate measurement of the gas mass flow.Based on the combination of the hot gas mass flow control system,the data processing scheme of the flow signal and the temperature compensation scheme of the hot gas measurement,this design constructs the overall structure of the multi-channel gas distribution instrument with STM32 as the main control chip.The standard gas is configured in different gradient ranges,and the experiment shows that the standard gas configured has good uniformity,accuracy and stability.At present,the system has been applied to the chip manufacturing process test project of Hefei Changxin Memory Technology Co.,LTD.