Bonded wafer with thermal stress relief structure and laser scribing process

Abstract

The invention discloses a bonded wafer with a thermal stress release structure. The bonded wafer comprises a glass wafer and a silicon wafer which are jointed with each other; a thermal stress release structure for laser scribing is arranged at the position close to a bonding contact surface of the bonded wafer; the thermal stress release structure is correspondingly arranged along a drafted laser scribing track; the stress release structure of the bonded wafer provided by the invention can prevent an original bonding region close to the scribing track from cracking, improve the laser scribing yield of the bonded wafer and reduce the scribing cost. The invention further discloses a laser scribing process; the laser scribing process comprises a thermal stress release structure process step, bonding wafer and laser scribing processing steps and the like; the laser scribing process can effectively release the thermal stress in the process of laser scribing so as to inhibit a thermal crack on a bonding contact surface, the mechanical property of the bonding contact surface is greatly improved, which is beneficial to the improvement of the MEMS (micro-electromechanical system) chip property; meanwhile, the process is simple and mature and can guarantee lower cost and higher yield.

Description

technical field [0001] The invention mainly relates to the field of micromachining (MEMS), in particular to a bonded wafer with a thermal stress release structure and a laser scribing process. Background technique [0002] As more and more MEMS devices are manufactured on bonded wafers, the dicing process of bonded wafers has become a key process that affects the yield of MEMS devices. At present, the commonly used bonded wafer scribing processes mainly include mechanical scribing and laser scribing. The mechanical scribing process needs to use coolant to cool the grinding wheel, which will introduce pollutants and affect the cleanliness of MEMS device chips, so it is rarely used for dicing bonded wafers; use laser beams for non-contact processing Laser scribing has gradually become the mainstream process for bonded wafer scribing due to its advantages of high precision, high efficiency and no pollution. [0003] Currently, the commonly used ablation laser dicing process (...

AI Technical Summary

Problems solved by technology

However, when the bonded wafer is diced using the stealth laser scribing process, it is necessary to use lasers with different wavelengths for scribing each layer of different material wafers, which makes the bonded wafer scribing process complicated. The equipment investment is expensive, and the dicing cost has increased sharply [Y. Izawa, S. Tanaka, H. Kikuchi, "Debris-free In-air Laser Dicing for Multi-layer MEMS by Perforated Internal Transformation and Thermally-induced Crack Propagation", MEMS 2008 , Tucson, AZ, USA, January 13-17, 2008, pp.822-827.]

Moreover, for the invisible laser scribing process, it is quite difficult to complete free-form scribing, which limits the application of the invisible laser scribing process

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