Advantages of wet chemical spin-processing for wafer thinning and packaging applications

Silicon thinning and stress relief are increasingly significant in the back end and assembly areas of semiconductor component manufacturing. The benefits of spin-processing technology with its accompanying aqueous chemical etchants can provide increased wafer and die strength, removal of surface damage, crystal defects and microcracks from backgrinding, and the ability to process wafers <100 μm in thickness using its Bernoulli handling system. ST Microelectronics experienced a 96.5% reduction in wafer breakage and scrap of backgrind material as a result of implementing spin-processing. It was confirmed that after wet chemical etching with an SEZ Spin-Processor 101, wafer warpage had decreased by 85%, wafer strength was up to 25 times stronger than with backgrind alone, and machine uptime was calculated at 99.4%. Using spin-processing for wafer thinning and strength enhancement also allows the user to control the surface finish. A smooth or rough surface can be achieved and wafers can be processed to these specifications while providing the same strength characteristics. As the roughened surface is created with chemicals, it does not introduce propagating crystalline defects, but leaves the wafer in an optimum state for back metal adhesion and contact resistance reduction. Similar results on highly doped wafers are easily obtained