The Study Of Silicon’s Recycle Process In Semicondor Manufacturing

In semiconductor manufacturing field, the dimension of silicon increase a lot in order to improve output and reduce cost, 300 mm silicon have been the mail material, and the critical dimension goes to 10 nm, this requires the better planarization of bare silicon. Test wafer is used for the equipment and process monitor, it’s built by bare silicon deposit different film which is similar with real process, after use, generally the test wafer can only be used once, after that, it generated lots of defect and damage, and has to be scrapped, to recycle test wafer will help to reduce the running cost of semiconductor manufacturing.CMP(Chemical Mechanical Planarization) is a key process in silicon polish, it contains both chemical and mechanical function, some factory used CMP to recycle test wafer directly, the test wafer polished by using alkaline slurry, and then cleaned by ultrapure water, but there are various film used on test wafer, with this method, the different film can’t be remove completely, but generate many new defect.In this thesis, the author will be build a test wafer recycle flow, remove the surface film first by wet etch, then polish the wafer and make the surface condition is good to match the requirement, the wet etch and CMP process will be analyzed, by multiple experiments, improvement solutions are proposed:1. By analyzing the theory and process, build a test wafer recycle model that removing the surface film by wet etch and then CMP polish.2. Studied the recycle flow by design multiple of engineering experiment, compare the different result of process, get a most optimized process parameter which could deliver the best recycle result.3. CMP is important step in the recycle flow, the polish equipment parameter setting impact the recycle result, the concentration of slurry has an obvious effect on polish ratio, and in this thesis, the relation of them is studied. Typical defects post polish which is scratch and particle contamination is also studied and solved, finally get a fully recycle flow can be used in mass production.