Design And Implementation Of Tungsten Nitride Anisotropic Etching Process For High Power Devices

Tungsten nitride is a very important wide band gap semiconductor material.Compared with other semiconductor materials,the chemical properties of tungsten nitride are not active,and have a strong chemical bond,but the high bond energy also makes it more active than other semiconductor materials.Tungsten nitride is a kind of ceramic material with excellent mechanical and thermal stability properties,which can be applied to the fabrication of semiconductor.In this paper,we mainly discuss the technology of tungsten nitride anisotropic etching for high power devices in semiconductor materials.This paper mainly studies and analyzes the design and implementation of tungsten nitride anisotropic etching process for high power devices.This paper first reviewed the research background and significance of research at home and abroad,and the related issue of the semiconductor material,etching technique,nitride semiconductor materials,and elaborates the basic principle and classification of dry etching and wet etching,lay a theoretical foundation for this study.According to the characteristics of tungsten nitride anisotropy,dry etching is chosen as the main research method,and the etching process is designed.The Centura machine applied materials based on tungsten nitride thin films for graphic development,using CHF3/CF4 as the etching gas,evaluated the effect of RF power,pressure,gas flow rate and other process parameters on the etching performance,the loss of Si and SiO2 optimized recipe of the substrate has better control.Electrical test results show that in the 0-5V range,maintain a good linearity,the resistance value curve is not obvious fluctuations.During the 5V voltage of the whole chip,the resistance value of each die is concentrated in 243KQ,and keep good uniformity.Si side wall morphology of the current layer is straight at the bottom of the side wall of the W2N will leave residues in etching,cause local short-circuit,electrical test,PCM test showed abnormal structure;current layer of Si by Pre-clean in W2N before and after deposition,the side wall angle is small,the menu in the same etching the side wall the W2N can also remove and clean.Based on this mechanism,the optimization of the front layer Si is carried out,and the angle of the side wall of the Si pattern is reduced.Finally,it is confirmed that the etching process can meet the requirements of W2N etching,ensure the W2N to remove the clean case,the lower level of loss in the controllable range,and in the film uniformity.The LDMOS device in this paper is tested through manufacture procedure,the measured results show that the device can deliver 350W output power over a(485?606)MHz band at 20ms pulse width,35.7%duty cycle,36V operate voltage,with more than 17dB power gain and 52%drain efficiency.