Non-damaging chemical photoresist strip process for copper/low-k interconnects

Photoresist removal using traditional plasma ash chemistries can cause severe degradation of low-k dielectric properties including increases in k-value and changes in critical dimensions. Restoration processes using silyating agents, for example, hexamethydisilazane (HMDS) have been used to partially restore the dielectric properties of films which have been exposed to a plasma ash. However, these processes do not fully restore the k-value of the as-deposited low-k film and as a result, the non-damaging photoresist removal has become a key challenge in ultra low-k integration. We present, herein, the photoresist strip results on CVD organosilicate glass (OSG), low-k films using ozone-saturated, deionized water (DIO₃) in a batch spray processor. This process yields no changes in the low-k dielectric properties or changes in critical dimensions. In addition, we also demonstrate the use of corrosion inhibitors to eliminate copper corrosion during the ozone process