Lithography

Patterning features on a wafer through lithography is a fundamental building block in creating MEMS. IMT offers both experience and the following technologies for MEMS lithography:  steppers, contact masks and shadow masking.

IMT offers both precision and repeatability. Our automated steppers can achieve precision layer to layer alignment and resolve submicron resolution features. Automation allows us to deliver mistake free exposure which insures repeatable processes resulting in volume production.

Similar to semiconductors, manufacturing MEMS is about stacking multiple layers of 2D structures on top of each other to fabricate 3D devices. Depending on the complexity of the device, the ability to tightly control the critical dimensions and layer-to-layer alignment are fundamental considerations for building MEMS. IMT offers several technologies depending on design requirements.

Photolithography and Grey Scale Lithography:

Tight CD and overlay controls are critical to building complex MEMS. Many programs require 15 to 20 mask layers, some > 30. IMT offers the following tool and process capabilities:

      • I-line 5x reduction steppers with sub-micron resolution
      • Standard 1x contact aligners
      • CD control: +/- 0.1 µm on 5x stepper, +/- 0.3 µm on 1x aligner
      • Overlay: +/- 0.15 µm on 5x stepper, +/- 3 µm on 1x aligner
      • Positive and negative tone, liftoff stencil
      • Thick resists, with resist options of thicknesses ranging from .75 µm to 80 µm and above, polyimide (including photo-imageable)
      • Front to backside alignment tolerance: +/- 1 µm

Shadow Masking:

For less precision metal deposition, shadow masking can also be used for depositing metals or metal stacks. IMT can make higher precision silicon shadow masks or stainless steel shadow masks.