Imprint is just one small step in device fabrication. Device fabrication is a
method that converts a starting state (blank substrate) to a finishing state
(device). There is a method or process that induces the transition.
The schematic to the right shows 3 levels of detail. The top sequence shows
the top level of the fabrication process. The start state is a Single Sided
Polished (SSP) wafer with a given flatness, the finish state is a completed
wafer. The fabrication process has properties of the number of device layers,
the device size and the device yield
The second level shown on the right is a single layer of the fabrication
process.
The imprint process is an element of the fabrication process, that must be
compatible with all surrounding states and processes. The third level on the
right shows the imprint step. There are methods (imprint process) and
properties (materials and patterns), that allows transitions between
intermediate fabrication states. This formalism allows the interfaces between
process steps, and requirements to be clearly appreciated. It also
emphasizes the importance to imprint of the starting state (substrate flatness,
topography and cleanliness) and the finishing state (substrate etch resistance
and cleanliness).
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defined topography. The layer 4 process or Imprint Cell Process consists of deposition, imprint etch and strip.
The key properties include the line width control and defect density after pattern etch and resist strip. The line
width control is primarily a function of the mold and the etch uniformity. The final state is a patterned SiO2 layer.
The final sequence isolates the imprint process where the start state is a spin planarized wafer with a known
surface flatness, the finishing state is an imprinted wafer ready for etch. The key properties are that there are no
repeating defects, a defect density lower than the Layer 4 target, residual layer thickness and the overlay of the
imprint pattern.
