Etch profile control of via opening

The invention relates to etch profile control of a via opening. A method includes forming a source/drain contact over a source/drain region; forming an etch stop layer over the source/drain contact, and forming an interlayer dielectric (ILD) layer over the etch stop layer; performing a first etch process to form a via opening extending through the ILD layer and a recess in the etch stop layer; oxidizing a sidewall of the recess in the etch stop layer; after oxidizing the sidewalls of the recess in the etch stop layer, performing a second etch process to extend the via opening down to the source/drain contact; and forming a source/drain via in the via opening after performing the second etching process. 本申请涉及通孔开口的蚀刻轮廓控制。一种方法，包括：在源极/漏极区域之上形成源极/漏极接触件；在源极/漏极接触件之上形成蚀刻停止层，并且在蚀刻停止层之上形成层间电介质(ILD)层；执行第一蚀刻工艺，以形成延伸穿过ILD层的通孔开口以及蚀刻停止层中的凹部；氧化蚀刻停止层中的凹部的侧壁；在氧化蚀刻停止层中的凹部的侧壁之后，执行第二蚀刻工艺以使通孔开口向下延伸到源极/漏极接触件；以及在执行第二蚀刻工艺之后，在通孔开口中形成源极/漏极通孔。