Controlled MoS₂ layer etching using CF₄ plasma

Abstract

A few-layered molybdenum disulfide (MoS2) thin film grown by plasma enhanced chemical vapor deposition was etched using a CF4 inductively coupled plasma, and the possibility of controlling the MoS2 layer thickness to a monolayer of MoS2 over a large area substrate was investigated. In addition, damage and contamination of the remaining MoS2 layer surface after etching and a possible method for film recovery was also investigated. The results from Raman spectroscopy and atomic force microscopy showed that one monolayer of MoS2 was etched by exposure to a CF4 plasma for 20 s after an initial incubation time of 20 s, i.e., the number of MoS2 layers could be controlled by exposure to the CF4 plasma for a certain processing time. However, XPS data showed that exposure to CF4 plasma induced a certain amount of damage and contamination by fluorine of the remaining MoS2 surface. After exposure to a H2S plasma for more than 10 min, the damage and fluorine contamination of the etched MoS2 surface could be effectively removed.

Emerging nanofabrication and quantum confinement techniques for 2D materials beyond graphene

“…Additionally, RIE processes are largely anisotropic in nature. Some popular plasma species for etching TMDCs include O 2 , 41-44 CF 4 , 41,45 and SF 6 . 46 Fluorinated plasma species (and other halogen species) are popular etching plasmas due to their high electronegatively.…”

Applications of Plasma in Energy Conversion and Storage Materials

“…Raman spectroscopic mapping confirms no D band in the planes of the resultant graphene, indicating etching only selectively occurs at the edges. In most cases, the plasma etching is used to thin down graphene (in basal plane) and other layered materials with controlled thickness, which enables studies on the layer‐dependent properties of 2D materials. Xiao et al demonstrated a soft and high throughput RF plasma etching of MoS 2 in SF 6 /N 2 (4.5:1) plasma .…”

Topography preserved microwave plasma etching for top-down layer engineering in MoS2and other van der Waals materials

“…Though various etching schemes have been explored, [19][20][21][22][23][24][25][26][27][28][29] a scalable and controllable thickness reduction down to the mono-or few-layer regimes starting from arbitrary thickness and area has not been demonstrated. Methods utilizing material chemistry exploit either harsh chemicals 19 or reactive plasma environment, are material specific.…”

“…Methods utilizing material chemistry exploit either harsh chemicals 19 or reactive plasma environment, are material specific. [21][22][23]28 Physical etching involves high temperature annealing, 25,27 laser assisted thermal ablation 20 or plasma environments, 24,26,29 results in degraded electrical properties. Postetch electrical characterization has not been performed in most cases, except for a few.…”