Abstract: Disclosed is a system for etching thin damage sensitive layers with a plasma. The invention finds particular application for etching damage sensitive thin films such as Gallium Arsenide on Aluminum Gallium Arsenide. Damage to sensitive thin films is avoided by lowering the DC bias of the cathode. The low DC bias is achieved by increasing the frequency of the power source producing the plasma. A reduced etch rate, suitable for etching thin layers, is achieved by pulsing the RF power source between a high power and a low power at a selected duty cycle.

Abstract: An embedded attenuated phase shift mask (“EAPSM”) includes an etch stop layer that can be plasma etched in a process that is highly selective to the underlying quartz substrate. Selectivity to the underlying quartz maintains a desired 180 degree phase shift uniformly across the active mask area. Conventional plasma etching techniques can be utilized without damage to the underlying quartz substrate. Alternatively, the etch stop layer comprises a transparent material that can remain intact in the mask structure.

Abstract: An embedded attenuated phase shift mask (“EAPSM”) includes an etch stop layer that can be plasma etched in a process that is highly selective to the underlying quartz substrate. Selectivity to the underlying quartz maintains a desired 180 degree phase shift uniformly across the active mask area. Conventional plasma etching techniques can be utilized without damage to the underlying quartz substrate. Alternatively, the etch stop layer comprises a transparent material that can remain intact in the mask structure.