A Study on Batch Etching Process for Wafer Thinning
Date Issued
2007
Date
2007
Author(s)
Zhan, Jing-Pou
DOI
zh-TW
Abstract
Thin Wafer is becoming the main stream in the semi-conductor industry. The most widely used technology is grinding process; the advantage of the process is better TTV values and faster production. On the other hand, the disadvantage of the process is that grinding requires mechanical method to remove the material, which means during the process it will grow a sub-surface damage (SSD) layer and residual stress. It gives more trouble for the post-decomposition process. SSD will also cause the wafer to be feebler and easily to break. When the wafer grind to 200 μm, Warp starts to become an issue; If applying the grinding process to further thin the wafer, the residual stress will meet its limit.
This research is base on the recent technology of grinding process, and then apply the batch etching method to improve the wafer thining. In the past, after the wafer grinding process, a batch etching was still applied. But its main purpose was to remove a layer with the residual stress of warp. This etching process was not used to thin the wafer; usually it only etched a few μm. This research is targeting a 50 μm etched on the wafer. First of all, applying the chemical etching method to improve the thinning process and also achieve the purpose of removing residual stress.
This research cuts the wafer into small piece of chips and then gives different treatment on the chips to figure out the process parameters. Taguchi Method was applied to explore the process parameters, system characteristics, and find out the best process parameters. Using the recent etch equipment to make effective adjustment, in the design phase, the primary target was to achieve a 100 μm thin wafer. Once it is successfully achieved, the next challenge would be the limitation of etching process.
When the wafer thickness is lower than 200 μm, usually its interior strength would not be able to support itself through the post-decomposition process. No matter it is etching in acid, cleaning by water, drying by spin, or carrying, it is easily to cause fractal on wafer. There for, this research specifically designs a vacuum chuck to hold the thin wafer on the acid-prof jig. Use the jig to support the thin wafer, so it would not break during the post-deposition process. This auxiliary device ultimately achieve the batch etching process.
Subjects
矽晶圓
薄化
濕式蝕刻
批次式蝕刻
真空治具
Silicon Wafer
Thinning
Wet Chemical Etching
Batch Etching
Vacuum Jig
Type
thesis
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