Performance Analysis And Design Of The Thermal Properties Testing Structure Of PECVD Silicon Nitride Film

With the rapid development of MEMS, the size of the devices is getting smaller. Under micro-scale, thermal properties of thin film are becoming more and more important, the thermal performance of film directly determines the stability of MEMS devices. Under the influence of size effect, thermal physical properties of thin film are very different from the bulk materials. Classical test theory has not adapted to the film thermal performance test. The classical test theory can no longer be used to test the thermal properties of thin films. In the field of IC and MEMS, silicon nitride film is always chosen as dielectric layer and the surface passivation layer. These need a silicon nitride thin film to show good thermal properties. In the view of the thermal properties of SiNx, especially its thermal conductivity, We should design corresponding test structures and analyze accurately, which is of great significance.First of all, this article simply describes the PECVD technique equipment, which be used to prepare the high frequency silicon nitride film. we studied the influence of the changes in SiH4/NH3、working pressure and substrate temperature in silicon nitride thin film(refractive index, density and deposition rate).Then we use the origin software to draw the relevant changing curve.In this paper, we briefly introduced the unique advantages of finite element simulation software COMSOL. Besides, the test model of the thermal conductivity, cantilever beam structure, is also putted forward, Meanwhile, we used COMSOL software to simulate and analyze the structure in the terms of thermal and mechanical. We learn that the longer length of the cantilever beam, the greater maximum temperature rise.In the end, this thesis mainly focuses on the preparation of silicon nitride thermal conductivity testing structure. L-edit was used to optimize the photo-mask and designed the processes about the structure of thermal conductivity test. For example, in order to avoid the climbing problem of aluminum lead, The sacrifice layer was no longer made into graph. In addition, the width of heating and measuring resistor stripe was increased, which make it easier for the preparation.In the process of experiments, we pointed out the related parameters and matters, which need serious attention. Graphics of each layer also were recorded in detail. Finally we build a test system that can provide vacuum environment, so as to accurately measure the thermal conductivity of silicon nitride.