Pellicle

A pellicle is a protective cover which can be applied to a photomask or reticle intended for use in a projection printer or wafer/mask stepper.

The pellicle is constructed of a thin transparent membrane attached to a metal frame.  This assembly is then permanently attached to the photomask or reticle, so that the membrane is held at a fixed distance from the photomask or reticle surface.

Any contaminate that originates from the clean room environment will end up on the surface of the pellicle, instead of on the photomask.  During the printing process, the image of this contamination will not generate a defect on the wafer, since it will be out of focus at the wafer surface.

With pellicle use, the danger of contaminating the photomask surface is significantly reduced, and printing yield can therefore be significantly increased.

Each pellicle is built to match a particular mask stepper or printer.  Therefore, the manufacturer's name and the model number of the machine must be provided when your order is placed.