Sidewall Chrome Alternating ApertureSCAA Mask
The SCAA test mask allows you to evaluate subwavelength imaging, perform resist profiling and evaluate phase-shift technology with minimal pitch-dependent phase error. At 248, it offers 100 nm imaging down to 200 nm pitch. A 193 mask is being built (spring 2002), and custom masks can be designed to meet unique specifications. The SCAA test mask provides resolution to a k1 of 0.25.
SCAA Mask Concept
Introduced by Marc Levenson in 1992, Sidewall Chrome Alternating Aperture (SCAA) Mask uses a pre-patterned phase-shift reticle that is recoated with chrome and resist, then written a second time to produce a mask that offers superior imaging performance and resistance to phase and amplitude errors due to fabrication and electromagnetic effects. The SEM image below shows an example SCAA mask (photo courtesy Marc D. Levenson).
After extensive analysis and testing of SCAA Mask in simulation, PAL has adapted the technology into an effective tool for evaluating subwavelength imaging.
SCAA Mask Fabrication
shown right, a SCAA mask is manufactured by taking a chromeless mask with
an appropriate phase pattern, re-coating it with chrome and resist, and
writing the desired exposure pattern in the chrome layer. The result is
a phase-shift mask structure where all quartz walls are covered by opaque
chrome and all chrome is supported by quartz.
Over Other Types of Phase-Shift Masks
SCAA vs. asymmetric bias comparison
The table below summarizes the comparison of important litho process and manufacturing criteria for SCAA and asymmetric biased masks.
Again, other designs shown below require detailed mask engineering and OPC even after biasing the space widths.
SCAA Test Mask Modules
The SCAA mask provides the following test modules:
These modules are useful for:
Mask is available through a collaborative project with