Comparing ICP and ECR Etching of HgCdTe, CdZnTe, and CdTe

Benson

Smith

2010

Inductively coupled plasmas (ICP) are the high-density plasmas of choice for processing HgCdTe and related compounds. Real-time examination of the ICP plasmas used to process HgCdTe would be desirable. In this preliminary study, the feasibility of using optical emission spectroscopy (OES) of ICP plasma used for processing HgCdTe has been examined. We have examined the utility of OES as a real-time diagnostic tool for HgCdTe device fabrication. In this preliminary study it has been found that mercury and cadmium can be detected but are dependent on several factors: sample area, material composition, etch rate, sample temperature, photoresist area, and plasma power. Furthermore, we found strong correlation between the amount of hydrogen detected by OES for samples with photoresist versus samples without photoresist while processing with hydrogen-based plasma. Hydrogen emission intensity decreased dramatically in samples with photoresist, contrary to the theory that photoresist adds hydrogen to the plasma effluent. It appears that hydrogen complexes with photoresist, reducing the global amount of hydrogen during the process. Furthermore, this phenomena may help to explain macroloading issues whereby additional photoresist area slowed HgCdTe, CdTe, and photoresist etch rates.

Section: Resultsmentioning

confidence: 99%

“…This hydrocarbon effluent may aid in volatilization of Cd from the chamber walls, as no intentional Cd was present on these silicon samples. [8][9][10]14,18 In order to verify that macroloading occurs, a second set of experiments was performed, as shown in Fig. 6a and b.…”

Section: Resultsmentioning

confidence: 99%

Effects of HgCdTe on the Optical Emission of Inductively Coupled Plasmas

Benson

Smith

2010

“…5,8,[11][12][13]15 However, to better control the compound semiconductor removal rate an unbalanced plasma etch can be used. If one of the semiconductor's constituents is removed more slowly than the others, this will limit the removal rate for the entire compound.…”

Section: Discussion and Resultsmentioning

confidence: 99%

Plasma Passivation Etching for HgCdTe

Benson

Smith

2009

Inductively coupled plasmas (ICP) are the high-density plasmas of choice for the processing of HgCdTe and related compounds. Most dry plasma process works have been performed on HgCdTe for pixel delineation and the p-to-ntype conversion of HgCdTe. We would like to use the advantages of ''dry'' plasma processing to perform passivation etching of HgCdTe. Plasma processing promises the ability to create small vias, 2 lm or less with excellent uniformity across a wafer, good run-to-run uniformity, and good etch rate control. In this study we developed processes to controllably etch CdTe, the most common passivation material used for photovoltaic-based HgCdTe devices. We created a process based on xenon gas that allows for the slow controllable CdTe etch at only 0.035 lm/min, with smooth morphology and rounded corners to promote further processing.

“…Both systems have been previously described. 27 XPS data were collected using a 16-channel detector, with a spherical capacitor analyzer at a take-off angle of 25 deg with respect to the sample surface plane. The emission from incident 1486.6 eV monochromatic Al K a x-rays was collected using a high-resolution energy analyzer with pass energy of 2.95 eV.…”

Section: Methodsmentioning

confidence: 99%

Plasma-Cleaned InSb (112)B for Large-Area Epitaxy of HgCdTe Sensors

Jaime-Vasquez

Martinka

et al. 2008

Self Cite

Plasma etching of (112)B InSb to prepare this semiconductor for the heteroepitaxy deposition of CdTe and initial studies of CdTe epilayers grown by molecular beam epitaxy (MBE) on InSb (112)B substrates cleaned with various plasma treatments are presented. X-ray diffraction rocking curve maps of the MBE CdTe epilayers on 3-inch InSb (112)B substrates have full-width at half-maxima (FWHM) values in the range of 20 arcsec to 30 arcsec. An etch pit density analysis of the 3-inch CdTe epilayers reveals a defect density of 1.0 · 10 7 cm -2 and 7.7 · 10 5 cm -2 at the center and edge of the wafer, respectively. Evaluation of a standard HgCdTe annealing process suggests that the removal of the InSb substrate is likely to be needed prior to any postgrowth annealing in Hg overpressure. Finally, we present a low-energy helium plasma exposure of wet-etched InSb (112)B substrates that provides a uniform epi-ready surface that is nearly stoichiometric, and free of oxide and residual contaminants.