基于晶圆减薄工艺的LT减薄片制备

声表面波(SAW)滤波器因其小型化、低插损及高品质因数(Q)值等性能，已广泛应用于移动通信系统中。钽酸锂(LT)/SiO₂/Si结构克服了传统温度补偿型声表面波(TC-SAW)器件制备工艺难的问题，但需减薄该结构上的LT厚度，而减薄过程会导致晶圆表面有损伤残留，影响器件性能。针对这个问题，该文开展了基于减薄与抛光制备LT减薄片的工艺研究，分析了砂轮目数、砂轮与工作台转速、砂轮进给率等减薄参数对LT晶圆表面损伤的影响，以及抛光压力对损伤的去除效果。研究结果表明，在优化的工艺参数下，减薄抛光后晶圆表面粗糙度为0.187 nm,损伤深度小于1 nm,减薄片制备的TC-SAW谐振器的阻抗图和Smith圆图表明晶圆性能和一致性良好。

Preparation of LT Thinned Wafer Based on Wafer Thinning Process

Surface acoustic wave (SAW) filters are widely used in mobile communication systems due to their miniaturization, low insertion loss and high Q value. The LT/SiO₂/Si structure overcomes the difficulties in the preparation process of traditional temperature compensated surface acoustic wave (TC-SAW) devices, but the thickness of LT on the structure needs to be reduced, and the thinning process will lead to residual damage on the wafer surface, affecting device performance. In order to solve this problem, this paper has carried out the research on the technology of preparing LT thin film based on thinning and polishing. The influences of thinning parameters such as the number of grinding wheel mesh, the rotation speed of grinding wheel and worktable, the feed rate of grinding wheel on the surface damage of LT wafer are analyzed, as well as the removal effect of polishing pressure on the damage. The research result shows that under the optimized process parameters, the surface roughness of the wafer after thinning and polishing is 0.187 nm, and the damage depth is less than 1 nm. The impedance diagram and Smith wafer diagram of the TC-SAW resonator prepared by the thinning wafer show that the wafer has good performance and consistency.