The Metal Lift-Off Process generally refers to the process of exposing a pattern into photoresist (or different material), depositing a thin film such as a metal or dielectric over the entire substrate area, and then removing or washing away the photoresist and excess metal leaving behind metal only in the designated patterned substrate area.
This process has commonly been done through a wet chemical process, but Takatori has developed a faster, more cost-effective, more environmentally-friendly alternative – Dry Metal Liftoff.
There are several methods currently used in Metal Lift-Off processes: toluene soak, negative/image reversal resist and the bi-layer method. These methods, however, produce chemical waste that requires proper disposal, often result in low yield, and offer challenges to reclaiming the often valuable waste metal.
The Dry Metal Lift-Off Process offers an efficient, high-yield process for removing unwanted metals. The process is simple. First, the substrate is laminated with an adhesive film compatible with metal required to be removed from the wafer surface. High-quality lamination is critical as wrinkles and bubbles are areas of improper adhesion. Once the film is laminated smoothly to the wafer, the adhesive film is gently peeled from the substrate at up to a 180° angle, taking with it the unwanted metal. A flash etch bath may be required to further remove particles.