Plasma chemistries for high density plasma etching of SiC

Abstract

A variety of different plasma chemistries, including SF6, Clz, IC1 and IBr, have been examined for dry etching of 6H-Sic in high ion density plasma tools (Inductively Coupled Plasma and Electron Cyclotron Resonance). Rates up to 4,500A-min-' were obtained for SF6 plasmas, while much lower rates (G300A.min") were achieved with C12, IC1 and IBr. The FZbased chemistries have poor selectivity for Sic over photoresist masks (typically 0.4-0.5), but Ni masks are more robust, and allow etch depths 2 1 0 p in the SIC. A micromachining process (sequential etch/deposition steps) designed for Si produces relatively low etch rates (<2,000A.min*') for Sic.

Inductively coupled plasma etch damage in 4H−SiC investigated by Schottky diode characterization

“…Previous studies have concluded that inductively coupled plasma (ICP) etching has several advantages compared to RIE when etching SiC. [1][2][3][4][5][6] In an ICP equipment the plasma is generated inductively at the top of the chamber at high energies (e.g., 600 W), and a second RF supply controls the ion energy on the sample. This makes it Ti Schottky diodes have been used to investigate the damage caused by inductively coupled plasma (ICP) etching of silicon carbide.…”

Plasma roughening of polished SiC substrates

“…Following Hong et al, F-based chemistries like SF 6 ; CF 4 or CHF 3 are well suited to obtain sufficient etch rates of approximately 1=2 mm=min across wafer diameters of 2 in [5]. As Steckl and Yih [6] pointed out, care must be taken to avoid micromasking, which is not only due to the mask material (they applied a layer of gold; the scattered residues can be detected only in close neighborhood of the mask) but also to etching of the electrode (mostly consisting of aluminum, then scattered across the whole sample).…”

Dry Etching of Bulk 4H-SiC and DLC/SiC Structure

“…One attribute of this technique is the high ion energy (> 200 eV) which is useful in breaking bonds in the SiC. The second is the so-called high density plasma sources, including Electron Cyclotron Resonance (ECR) [5] and Inductively Coupled Plasma (ICP) [3][4][5]. These tools operate at lower pressure (1-2 mTorr) and lower ion energy but with higher ion fluxes (> 10 11 cm À3 ).…”