Plasma Etching Pre-treatment for a TEM Lamella Preparation of 3D NAND with High Aspect Ratio

The 3D NAND sample with high aspect ratio (HAR) etched by plasma was investigated. By controlling the plasma etching parameters, a relatively high etch rate could be obtained. Moreover, with appropriately controlling the etch time, we could etch top region of HAR sample with expected number of layers, which could help us to completely analyze the high aspect ratio sample with TEM cross-section analysis, especially for the middle region of 3D NAND.

Inductively Coupled Plasma Etching of Pt/Ti Electrodes in Cl-Based Plasma

Dry etching of Pt/Ti film was carried out using Cl2/Ar plasmas in an inductively coupled plasma (ICP) reactor. The influence of the various process parameters, such as RIE power, ICP power and Cl2/Ar gas mixing ratio, on the etch rate and selectivity of photoresist to Pt/Ti film were investigated systematically and optimized. It was revealed that the etch rate and the selectivity strongly depended on the key process parameters. The etch rate was found to increase dramatically with increasing of RIE power and ICP power. But by changing the ratio of Cl2 to the total gas, the maximum etch rate could be obtained at the proper ratio of 20%. The results also indicated too low or too high RIE power and the Cl2 ratio was detrimental to the selectivity. The optimized parameters of Pt/Ti dry etching for high etch rate and low selectivity of photoresist to Pt/Ti were obtained to be pressure: 10mT, RF power: 250W, ICP power: 0W, Cl2: 8sccm (standard cubic centimeters per minute), Ar: 32sccm.

ICP Etching of 4H-SiC Substrates

Due to its inert chemical nature, plasma etching is the most effective technique to pattern SiC. In this paper, dry etching of 4H-SiC substrate in Inductively Coupled Plasma (ICP) has been studied in order to evaluate the impact of process parameters on the characteristics of etching such as etch rate and trenching effect. Key process parameters such as platen power and ICP coil power prove to be essential to control the SiC etch rate. On the other hand, the ICP coil power and the working pressure mainly master the trenching effect. Our results enlighten that high etch rate with minimal trenching effect can be obtained using high ICP coil power and low working pressure.

Hexagonal Faceted SiC Nanopillars Fabricated by Inductively Coupled SF6/O2 Plasma Method

We demonstrate a top-down fabrication technique for nanometer scale silicon carbide (SiC) pillars by using inductively coupled SF6/O2 plasma etching. The obtained SiC nanopillars exhibit high anisotropy features (aspect ratio ~ 6.5) with high etch depth (>7 μm). The etch characteristics of SiC nanopillars obtained under these conditions show a high etch rate (550 nm/min) and a high selectivity (over 60 for Ni mask). We obtained hexagonal symmetry of SiC nanopillar, which might be attributed to the crystallographic structure of the SiC phase.

Fabrication of SiC Nanopillars by Inductively Coupled SF6/O2 Plasma

A top-down fabrication technique for nanometer scale silicon carbide (SiC) pillars has been demonstrated by using inductively coupled SF6/O2 plasma etching. At optimal etching conditions, the obtained SiC nanopillars exhibit high anisotropy features (aspect ratio ~ 6.5) with high etch depth (>7 μm). The etch characteristics of SiC nanopillars under these conditions show a high etch rate (550 nm/min) and a high selectivity (over 60 for Ni).

Development of Multiple-Step SOI DRIE Process for Superior Notch Reduction at Buried Oxide

A novel two step etch process using the Bosch-etch mechanism to prevent notching on an SOI wafer is presented. The first etch step is used to attain the maximum etch depth with high etch rate and stop before the buried oxide (BOX). Followed by the second etch step with lower etch rate and tuned to soft land on the BOX to etch the remaining depth. In addition to that it is tailored to also provide a tapered etch profile which is beneficial in reducing the notch if over etching occurs.