Inter-metal dielectric layer structure and its forming method

Abstract

An inter-metal dielectric (IMD) layer structure and its forming method are disclosed. The IMD layer structure is formed between a first conducting layer and a second conducting layer and includes a first dielectric layer overlying the first conducting layer, a glass layer overlying the first dielectric layer, an etching stop layer overlying the glass layer, and a second dielectric layer overlying the etching stop layer under the second conducting layer. The etching rate of the etching stop layer is relatively low so that it can prevent the glass layer etched out. Therefore, a long-time etching can be used to obtain a better through hole profile.

Dependencies are inferred from the claim text.