| Summary: | 碩士 === 國立交通大學 === 工學院半導體材料與製程設備學程 === 104 === This paper is mainly investigate DSP clean acid , the DSP clean is a single wafer clean process .Adding a wafer rinse step before chemical DSP (Diluted Sulfuric Acid and Peroxide Mixture) direct dispensing can effectively eliminate the instant ESD (Electro-static Discharging) caused damaged on the post metal etch clean process . The ESD damage may occur on the very moment when the first DSP chemical hit the spot on the dry wafer surface. Adding water rinse can avoid the direct hitting of DSP on the wafer surface to avoid the very short time electrochemical reaction of DSP and the metal lines.
The potential electrochemistry issue can cause the yield fail on the post clean of metal dry etch . These failed sites are easily to be neglected since there may be only one or very few failed sites on the wafer. But if we gather the failed sites from different wafers, we can see a ring type distribution 90 mm from wafer center.
The partition check were done after metal dry etch, metal dry etch scrubber and metal dry etch clean to make sure the occurrence is on which step. The electrochemistry issue was observed after metal dry etch clean. The failure site of that die will be failed on the yield test.
From the experiment result, the electrochemistry defects matched the chemical boom swing setting positions. With pre DI water step, the electrochemistry can be avoided. The mechanism could be the single point discharging issue when the dry water surface was hit by the chemical (Conductor). The failed sits could be the burned out metal lines or the minor metal corrosion. The wafer surface was suspected to be charged somewhere in metal line or some well, and the conductor contact in a small area caused the discharging to occur in a very short time. Pre DI water dispense can disperse the wafer surface charging condition and to avoid the direct ESD occurrence.
The pre DI water rinse recipe can effectively reduce the electrochemistry effect .The obvious difference between the adding of new process, the electrochemistry effect almost disappeared.
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