Dry etch processes can provide excellent profile control. The energetic ion bombardment increases the etch rate on the exposed surface relative to those regions protected by the mask, so vertical sidewalls with negligible undercutting are readily achieved. Depending on the balance between chemical and physical contributions to the dry etch, it is possible to vary the profile from isotropic/crystallographic to vertical to angled. With vertical profiles, smaller critical dimensions are achievable. The ion enhancement also removes the dependence on the pattern alignment relative to the wafer crystal planes. The proper balance of chemical etching and physical sputtering allows dry etch processes such as RIE, HDPE, RIBE and CAIBE to produce devices with small feature sizes and vertical profiles. Although some electronic damage results from the ion bombardment that permits fine features and profile control, these processes are and will remain the basis of most III-V device fabrication.
Dry etching of GaAs and related alloys, Page 1 of 2
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