GaAs Thin Wafer的強(qiáng)度提升探究

上幾天研究了一下GaAs的拋光，其實(shí)化合物半導(dǎo)體的拋光都會(huì)面臨薄晶圓強(qiáng)度小，晶圓有著天然的解離鏡像，容易裂片的問題。

圖片來源于網(wǎng)絡(luò)

如上圖，如果發(fā)生晶圓裂片，經(jīng)常四分五裂，就這能做報(bào)廢處理。

如何提高晶圓的強(qiáng)度，如上文提到的降低晶圓表面粗糙度可以提高。

如何實(shí)現(xiàn)呢？

早起大家研究的有兩種方法，第一個(gè)是通過減薄之后的拋光，把磨砂面變成鏡面，其實(shí)就是降低表面粗糙度，另外一個(gè)是腐蝕。今天找到一篇做的對(duì)比得論文，我們探究一下。

The study was done on the four-inch<100>GaAs wafers. The wafers were measured so that the total thickness variations (TTV) before and after grinding were less than 5 microns. All wafers were wax-mounted on the sapphire disk by the Logitech bonding machine.

TTV小于5um。

采用GN研磨設(shè)備。

The wet etch recipe used for this test was: 1(36.5% HCl): 4 (30% H2O2): 40 (DI), with an etch rate of about 0.3 microns per minute at room temperature.

the test wafers were loaded on the 12” Lap Master polishing machine. The wafer was rotated on the polishing pad. Polishing slurry was supplied to the pad and the removal rate was 1.2 microns per minute.

腐蝕和拋光工藝采用以上參數(shù)。

制備五個(gè)樣品

1）減到100um的毛坯wafer

2）減到105um的然后腐蝕5um，

3）減到110um，然后腐蝕10um。

4）減到115um，然后腐蝕15um。

5）減到110um，然后拋光10um。

The Wafer Strength Measurements were taken by using an AIKO material strength tester manufactured by AIKO Engineering Inc. in Japan.The accuracy of the wafer strength measurement is+/- 0.01 lbs. 應(yīng)力測(cè)試設(shè)備和精度要求。

urface roughness (Ra) [*]measurements by Chapman machine (model MP2100 non-contact measurement system)

1、3、5三個(gè)waferTTV對(duì)比，Etching的最差

拋光的5號(hào)樣品強(qiáng)度大

The lowering of surface roughness is a major factor for wafer strength improvement, the smoother is the surface, the stronger is the wafer. The smooth surface will help preventing breakage during the wafer demounting and solvent cleaning. It is very important to do polishing instead of wet etching process in the wafer thinning operation to minimize the thickness variation, and reduce the surface roughness to improve the wafer strength. By implementing the polishing process in our high volume production line the wafer breakage rate was reduced from 9.13% to 0.59%.

總的來說，多拋光，或者在拋光過程中，加入化學(xué)腐蝕的作用，比如加雙氧水等。