BSC──ISFET的特殊工艺研究

INVESTIGATION OF SPECIAL PROCESSES FOR BSC-ISFET

本文研究了背面引线离子敏感场效应器件Ｂａｃｋｓｉｄｅｃｏｎｔａｃｔｉｏｎｓｅｎｓｉｔｉｖｅｆｉｅｌｄｅｆｆｅｃｔｔｒａｎｓｉｓｔｏｒ（ＢＳＣ－ＩＳＦＥＴ）的特殊工艺技术。重点阐述了双面光刻，各向异性腐蚀，深坑加工，腐蚀自停止等技术，实现了源漏电极从芯片背面引出，给出了扫描电镜分析照片。提出了一个合理，实用的腐蚀配方及条件：在７７℃恒温腐蚀溶液中（ＫＯＨ：ＩＰＡ：Ｈ２Ｏ＝２５．６：１６．５ｍｌ：６０ｍｌ），腐蚀约５小时３０分钟，腐蚀速率为５５μｍ／ｈ－６０μｍ／ｈ。得到了光滑、平整的坑底和坑壁，棱角分明斜度正常（５４．７°），重复性好，实验结果表明其接触电阻小于４Ω，达到ＢＳＣ－ＩＳＦＥＴ设计要求。

This paper investigates the special fabrication processes for the Back Side Contact Ion Sensitive Field Effect Transistor (BSC-ISFET),including the double-sided photolithography ,the anisotropic etching,the deep etching notch processing, the automatic etch-stop technique and etc.The technique of contacting the source-drain electrodes from the back side of the chip is realized and the SEM photopicture is shown. The optimum etching conditions are reported.The contaCting resistance is less than 4Ω.The results satisfied the design requirement of the BSC-ISFET.