MDP in a Nutshell: Understanding Mask Data Preparation

ABSTRACT

When an IC design has been physically verified and is past the application of resolution enhancement technologies, such as optical and process correction (OPC), the design is ready to move on to the next step on the way to wafer manufacturing. That step is creation of photomasks, the "negatives" that guide the patterns of light used in wafer photolithography. Mask data preparation (MDP) is the process that readies the circuit design data for delivery to mask writing machines. Never clearly perceived as part of either of the larger IC design or manufacturing communities, mask data preparation has been traditionally orphaned between them.

The race to smaller feature sizes has pushed the photolithographic process into the territory of sub-wavelength feature patterning. Sub-wavelength patterning requires manufacturing processes capable of creating design features smaller than the wavelength of the light used to expose them. Over the past few years, the expanding effects of smaller feature sizes have led to development of techniques for adapting and enhancing mask designs to ensure that the patterns will print accurately. This has forced process technology to use subwavelength and low K1 lithography as well as adding RET and OPC to the design. Adding enhancements has in turn expanded the volume of design data by as much as one or two orders of magnitude.