Manufacturing of 8 million Q-factor micro hemispherical resonator gyroscopes via patterned coating technology

As the core sensitive element of high-precision inertial navigation systems, the Q-factor and frequency splitting of the micro hemispherical resonator gyroscope (mHRG) are critical determine the performance of the inertial measurement unit (IMU). However, the continuous films formed by traditional coating processes introduce significant damping, leading to a substantial decrease in the Q-factor and severely restricting the improvement of the mHRG's accuracy. In this paper, a patterned coating solution based on magnetron sputtering physical vapor deposition is proposed. High-precision patterned deposition of Ti/Pt thin films on the three - dimensional complex curved surface of the shell has been successfully achieved. The performance of the packaged device was characterized. The results indicate that the Q-factor loss rate of the mHRG after patterned coating is less than 14%, and the measured Q-factor is as high as over 8 ×10⁶. The circumferential Q-factor uniformity is better than 1%, and the frequency splitting is controlled within 1 mHz. All indicators outperform those of the traditional coating process. Mechanism analysis indicates that the patterned design significantly reduces the additional damping caused by the friction at the grain boundaries of the thin film and at the film-substrate interface by greatly reducing the coverage area of the thin film, which is the key to achieving a high Q-factor. Based on the harmonic error analysis theory, this paper establishes a correlation model between the film pattern and the circumferential uniformity of the device as well as frequency splitting, ensuring the uniformity of various performance parameters of the gyroscope in its working mode. Model calculations and experimental results have verified that this patterned film can significantly enhance the Q-factor, and is effective in suppressing the circumferential Q-factor non-uniformity and frequency splitting, providing key process support and theoretical basis for high-performance mHRG. We proposed a patterned coating process using magnetron sputtering and 3D masks. -Prepared mHRG has Q-factor>8M, outperforming traditional full-coat devices. -Clarified the principle by which patterned thin films reduce thin film damping. -The thin film patterns based on the harmonic error theory ensure uniformity.