Fabrication Technology For Three-dimensional Symmetrical Micro-hemispherical Resonator Of MEMS Hemispherical Resonator Gyroscope

The micro-scale hemispherical resonator gyroscopes based on MEMS manufacturing technology are characterized by small size,light weight,low cost and suitable for volume production while absorbing the advantages of full-angle measurement of traditional hemispherical resonator gyroscopes.In the process of fabricating hemispherical shell structure by sacrificial layer process,whether the molds of hemispherical resonator on single crystal silicon have smooth surface and structural symmetry has decisive influence on the performance of hemispherical resonator.However,the longitudinal symmetry of hemispherical harmonics is poor while using the traditional HNA etching solution,and the comprehensive performance of hemispherical resonance gyro against horizontal and vertical acceleration is poor.Therefore,in order to fabricate the fabrication of 3d symmetric hemispherical resonator,it is urgent to carry out the research on accelerating the longitudinal corrosion rate and realizing the 3d symmetry of hemispherical resonator in the process of using HNA etching solution to fabricate the micro-hemispherical gyroscope resonator.Based on the above research purposes,the main research work and conclusions of this paper are as follows:1.Aiming at the problem that the three-dimensional symmetry of hemisphere mold is difficult to be achieved by the traditional HNA etching solution,a new method,that using SiO2 grown by thermal oxidation process as the mask layer,wasput forward,in order to accelerate the longitudinal etching rate and achieve the three-dimensional symmetry of resonator mold in the process of manufacturing the micro-hemispherical resonator mold by using HNA etching solution.According to this method,the experimentswere designed and carried out to explorethe morphologic evolution of the Si-based molds under large and small etching windows.2.The morphologic evolution of silicon samples under etching windows with large and small radius etched by HNA solution was summarized and analyzed.According to the characteristics of the etching morphology of the samples under etching windows with large and small radius,the method of measuring the etching morphology was proposed.Then,by summarizing the experimental data,the evolution of the annular bottom phenomenon of samples with large etching window and the evolution of longitudinal/lateral etching depth and etching ratewith etching window radius and etching time of the samples unider small etching window were studied in detail.3.Based on the morphology evolution of silicon molds etched by HNA solution,the complete method of fabricating the 3-D symmetrical hemispherical resonator was put forward,and some technical difficulties in practical process is optimized.Then the 3-D symmetry and surface smoothness of the samples were measured,and the parameters such as the vertical radius deviation and the sphericity devetion of the hemispherical resonator molds are obtained.Finally,by optimizing the fabricating and releasing process of hemispherical resonator,the three-dimensional symmetric hemispherical resonator was fabricated.