Antireflective structures in CdTe and CdZnTe surfaces by ECR plasma etching

Varesi

et al. 2005

Self Cite

The surface of (211)B HgCdTe has been studied by reflection high-energy electron diffraction (RHEED) and atomic force microscopy (AFM). RHEED analysis of the as-grown Hg-rich molecular beam epitaxy (MBE) (211)B HgCdTe suggests the surface reconstructs by additional Hg incorporation. The plasma-etched (211)B HgCdTe surface is crystalline but stepped and facetted. RHEED analysis indicates asymmetric pyramids (base dimensions Ϸ 0.5 ϫ 1.1 nm) are formed to minimize surface Hg concentration. The AFM examination of plasma-etched (211)B HgCdTe reveals oriented mesoscopic features.

Section: Methodsmentioning

confidence: 99%

Surface structure of plasma-etched (211)B HgCdTe

Benson

Varesi

et al. 2005

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“…A detailed description of the ECR reactor and specific etch chemistries for II-VI materials are given elsewhere. 6 For ECRetch experiments, several patterns were exposed (at equal energy densities) on a single wafer and then H 2 -development etched. The wafer was then cleaved so that each pattern could be attached to separate Si carrier wafers for ECR etching at selected times.…”

Section: Methodsmentioning

confidence: 99%

Processing and characterization of a-Si:H photoresists for a vacuum-compatible photolithography process

Jacobs

Robinson

et al. 2004

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The vision of achieving a completely in-vacuum process for fabricating HgCdTe detector arrays is contingent on the availability of a vacuumcompatible photolithography technology. One such technology for vacuum photolithography involves the use of amorphous-hydrogenated Si (a-Si:H) as a photoresist. In this work, we deposit a-Si:H resists via plasma-enhanced chemical-vapor deposition (PECVD) using an Ar-diluted silane precursor. The resists are then patterned via excimer laser exposure and development etched in a hydrogen plasma where etch selectivities between unexposed and exposed regions exceed 600:1. To determine the best conditions for the technique, we investigate the effects of different exposure environments and carry out an analysis of the a-Si:H surfaces before and after development etching. Analysis via transmission electron microscopy (TEM) reveals that the excimer-exposed surfaces are polycrystalline in nature, indicating that the mechanism for pattern generation in this study is based on melting and crystallization. To demonstrate pattern transfer, underlying CdTe films were etched (after development of the resist) in an electron cyclotron resonance (ECR) plasma, where etch selectivities of approximately 8:1 have been achieved. The significance of this work is the demonstration of laser-induced poly-Si as an etching mask for vacuum-compatible photolithography.

“…[1][2][3][4][5] The larger the hydrogen-gas percentage is, the more isotropic the etch is. This is consistent with the theory that the argon component effects a removal by sputtering, while the hydrogen component primarily reacts chemically with the HgCdTe.…”

Section: Argon To Hydrogen Concentrationmentioning

confidence: 99%

“…1 Features, such as mesas, vias, lenses, and antireflective structures have been formed in HgCdTe and related materials for infrared detector applications. 2 This chemistry has the advantage that it etches II-VI materials at a high rate without severe damage. In semiconductors, such as HgCdTe, CdZnTe, and CdTe, dienergetic-ion bombardment from the plasma maintains the stoichiometry of ternary alloys without the addition of gases, such as methane (CH 4 ), that can cause polymer deposition on the sidewall of a plasma reactor and the etched thin film.…”

Section: Introductionmentioning

confidence: 99%

“…2 The substantial erosion rate of the resist is known to be a limiting factor, preventing the achievement of even higher selectivities and the concomitant etching of deep trenches in these materials. 5 Separate measurements of the erosion rates of conventional photoresists and II-VI materials have been made under a variety of plasma conditions.…”

Section: Introductionmentioning

confidence: 99%

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Development of a high-selectivity process for electron cyclotron resonance plasma etching of II-VI semiconductors

Benson

Thomas

et al. 2002

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The erosion rate of resist during electron cyclotron resonance (ECR) plasma etching of II-VI semiconductors is the limiting factor for the selectivity (values range from 5:1 to 10:1). We have measured the erosion rates of AZ 1529, a commercially available diazonaphthoquinone (DNQ) novolak photoresist, under plasma conditions optimized for etching of the underlying semiconductor and have developed an in-situ technique to "harden" the resist by exposing it to an argon-only ECR plasma. A subsequent standard plasma process can then be used to etch the II-VI material, thereby achieving selectivity values greater than 50:1.