Inductively Coupled Plasma Etching for Large Format HgCdTe Focal Plane Array Fabrication

Authors: Smith, E.P.G.; Venzor, G.M.; Newton, M.D.; Liguori, M.V.; Gleason, J.K.; Bornfreund, R.E.; Johnson, S.M.; Benson, J.D.; Stoltz, A.J.; Varesi, J.B.; Dinan, J.H.; Radford, W.A.

Source: Journal of Electronic Materials, Volume 34, Number 6, June 2005 , pp. 746-753(8)

Publisher: Springer

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Abstract:

Inductively coupled plasma (ICP) using hydrogen-based gas chemistry has been developed to meet requirements for deep HgCdTe mesa etching and shallow CdTe passivation etching in large format HgCdTe infrared focal plane array (FPA) fabrication. Large format 2048 × 2048, 20-μm unit-cell short wavelength infrared (SWIR) and 2560 × 512, 25-μm unit-cell midwavelength infrared (MWIR) double-layer heterojunction (DLHJ) p-on-n HgCdTe FPAs fabricated using ICP processing exhibit >99% pixel operability. The HgCdTe FPAs are grown by molecular beam epitaxy (MBE) on Si substrates with suitable buffer layers. Midwavelength infrared detectors fabricated from 4-in. MBE-grown HgCdTe/Si substrates using ICP for mesa delineation and CdTe passivation etching demonstrate measured spectral characteristics, RoA product, and quantum efficiency comparable to detectors fabricated using wet chemical processes. Mechanical samples prepared to examine physical characteristics of ICP reveal plasma with high energy and low ion angle distribution, which is necessary for fine definition, high-aspect ratio mesa etching with accurate replication of photolithographic mask dimensions.

Keywords: HGCDTE; DRY ETCHING; INDUCTIVELY COUPLED PLASMA (ICP); LARGE FORMAT; MIDWAVELENGTH INFRARED (MWIR); SHORT-WAVELENGTH INFRARED (SWIR); MOLECULAR BEAM EPITAXY (MBE); LIQUID PHASE EPITAXY (LPE)

Document Type: Research article

Publication date: 2005-06-01