More than one million micro-electronic field effect transistors (e.g., complementary metal-oxide-semiconductor (CMOS) field effect transistors) are fabricated on a substrate (e.g., semiconductor wafer) to form an integrated circuit. During the fabrication process of the integrated circuit, a photoresist is deposited, exposed, and developed to create a mask utilized to etch the underlying layers.
To produce the integrated circuit, implanting ions into various portions of the integrated circuit is necessary. During ion implantation, wafers are bombarded by a beam of electrically charged ions, called dopants. Implantation changes the properties of the material where the dopants are implanted in order to achieve a particular electrical performance. These dopants are accelerated to an energy that will permit them to penetrate (i.e., implant) the film to a desired depth. During implantation, high-dose or high-energy ions may implant in the photoresist layer and cause a hard, crust-like layer to form on the surface of the photoresist layer. The crust layer is difficult to remove using conventional stripping processes. Moreover, if the crust layer or underlying photoresist is not removed, the residual photoresist becomes a contaminant during subsequent processes. Thus, an improved method for stripping a photoresist is still in great demand.