Energy beam patterning of protective layers for semiconductor devices

DETAILED DESCRIPTION According to the present invention, a method for forming resist or other protective patterns on a substrate is disclosed using exposure of a layer of heat- or selected wavelength-sensitive protective material to a focused, controlled laser or other energy beam comprising electromagnetic radiation traversed over the material layer in a selected path such that portions of the material layer are cured to define a protective pattern over the substrate.
As an alternative to traditional masking techniques, the present invention may be used to form patterns of conventional configurations on substrates, such as semiconductor wafers, partial wafers or singulated devices, with at least as great precision and greater repeatability and speed, than is achievable using conventional masking techniques.
Furthermore, the present invention may be used to create protective formations over wires and other conductors during semiconductor fabrication without the use of masking techniques.
The method of the present invention involves covering at least a portion of a substrate with a layer of a heat-sensitive or selected wavelength-sensitive protective material, exposing selected portions of the material to a beam of electromagnetic radiation such as a laser beam to completely cure those portions of the material and washing away the uncured portions of the material remaining on the substrate.
A precuring step may also be employed to partially cure the entire material layer before exposure of selected portions thereof to the electromagnetic radiation beam.
The cured material remaining after developing and/or washing defines the desired protective pattern on the substrate.
In one exemplary embodiment, a layer of EPON Resin SU-8 formulated in solution as a photoresist is deposited on a substrate to a desired thickness and partially cured to a B-stage.
Portions of the partially cured resin material are subjected to a traversing laser beam having an appropriate wavelength and energy density sufficient to initiate the cure of the B-stage resin material to a C-stage