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PMMA Positive Resists

Part of the Kayaku Advanced Materials Line
Photoresists & Specialty Chemicals

PMMA (polymethyl methacrylate) is a versatile polymeric material that is well-suited for many imaging and non-imaging microelectronic applications. PMMA resists are simply PMMA polymer dissolved in a solvent like anisole (safe solvent). Exposure causes scission of the polymer chains. PMMA is most commonly used as a high resolution positive resist for direct write e-beam offering extremely high-resolution, ease of handling and excellent film characteristics. PMMA is also used as a protective coating for wafer thinning, as a bonding adhesive and as a sacrificial layer.

Material attributes:

  • Positive tone
  • E-beam and X-ray imageable
  • Wide range of film thicknesses
  • Resist developers and strippers
  • Excellent adhesion to most substrates

Material uses:

  • Wafer thinning
  • Protective coatings
  • PHEMT
  • Multi-layer T-gate processes
  • Other direct-write e-beam processes

Copolymer resists are based on a mixture of PMMA and ~8.5% methacrylic acid. Copolymer MMA (8.5) MAA is commonly used in combination with PMMA in bi-layer lift-off resist process where independent control of CD size and shape of each resist layer is required. Standard copolymer resists are formulated in ethyl lactate and are available in a wide range of film thicknesses. All PMMA and copolymer resists are available in package sizes from 500ml to 20 liters.

Material uses:

  • Multi-layer T-gate processes
  • Other direct write e-beam processes

Material attributes:

  • Compatible with multi-layer processes
  • Excellent adhesion to most substrates

Schematic of a T-gate illustrating various product layers