Acronym · Physical Design & Signoff
MDP (Mask Data Preparation)
The chain of post-tapeout steps that converts design layout into mask writer instructions, including sizing, boolean operations, OPC, mask rule checking, fracturing and jobdeck assembly.
- Also known as
- Mask data prep, Post-tapeout flow
- Type
- Acronym
- Domain
- Physical Design & Signoff, Mask data prep
Notes
Runtime for a single advanced-node layer can run to thousands of CPU hours, making MDP a real schedule item.
Overview
MDP, short for mask data preparation, is the set of steps after tapeout that turns a chip's layout database into the data that mask writing tools need to make photomasks. It covers geometric processing, resolution enhancement such as optical proximity correction, checks against mask manufacturing rules, fracturing into simple shapes, and the job deck that describes how patterns are arranged on each mask. MDP is carried out by foundries, mask shops and some large chip companies, using specialised software.
How it works
The input is the final layout, typically in GDSII or its more compact successor OASIS, standardised by SEMI as P39. Chip finishing adds structures such as seal rings and fill, and the reticle layout places one or more copies of the die with scribe lines, alignment marks and test structures. Graphics operations then derive the mask layers from the drawn layers, and resolution enhancement techniques such as optical proximity correction or inverse lithography reshape features so that they print correctly on the wafer.
Mask writers cannot draw arbitrary polygons, so fracturing breaks every shape into the simple figures a writer handles, such as rectangles and trapezoids for variable-shaped-beam writers, or into the formats used by multi-beam writers. Mask process correction compensates for distortions of the mask-making process itself, and mask rule checks catch features too small or too close for the mask shop to make. The output goes to the writer in its own format or in OASIS.MASK, the SEMI P44 form of OASIS for mask tools, with a job deck in the MALY format of SEMI P45 describing how the pieces fit together.
Data volume is the main practical problem. A 2013 white paper published by Semiconductor Engineering noted that post-OPC files at the 28 nm node already reached hundreds of gigabytes, and that the trend grows at smaller nodes, so MDP flows are tuned to keep delivery times to the mask shop predictable.
Examples
- Converting an OASIS tapeout into variable-shaped-beam writer data, with optical proximity correction applied to every critical layer.
- A mask shop receiving OASIS.MASK files with a MALY job deck and checking them against mask rules before writing.
- Fracturing a layer into a multi-beam writer format instead of variable-shaped-beam data, as current MDP tools support.
- A reticle that carries several different dies, arranged and placed through the job deck.
Why it matters
Related terms
Part of the Physical Design & Signoff glossary, with every term in the topic and the lifecycles, tools and standards that use them.
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Roles
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Last reviewed . Written by The Semiconductor Hub editorial team. The full glossary