Selective etching of GaAs over Al0.2Ga0.8As semiconductor in pulsed DC BCl3/SF6 plasmas

We investigate inductively coupled plasma (ICP) deep dry etching of Al0.8Ga0.2As for photonic crystal (PC) fabrication using a Cl2/BCl3/CH4 gas mixture. On the basis of our previous report [Y. Kitabayashi et al., Jpn. J. Appl. Phys. 52, 04CG07 (2013)], we obtained a PC structure having air holes deeper than 1.5 µm and a diameter of 120 nm by adjusting the gas flow rate and increasing the process pressure. In this study, silicon nitride (SiNx) and SiO2 were both used as the mask layer. Furthermore, samples with SiNx and SiO2 masks for ICP deep dry etching were also fabricated and compared. The vertical profile of the PC structure with the SiNx mask layer displayed a rounded shape that was caused by the charge up in the mask layer. Then, a thinner mask layer was used to ease the effects of mask retardation and charge up. As a result, a PC structure with a SiNx mask layer having air holes deeper than 1.7 µm and a diameter of 190 nm was successfully fabricated.

Section: Introductionmentioning

confidence: 99%

Dry etching of Al-rich AlGaAs with silicon nitride masks for photonic crystal fabrication

Zhang¹,

Togano²,

Hashimura³

et al. 2015

“…30) In this study, DC pulse biasing was also introduced in the etching of MTJ-related materials to explore the possibility in improving the etch characteristics of the MTJ-related materials such as CoFeB, CoPt, MgO and W using an optimized CO/NH 3 gas mixture and the etch characteristics were compared with those etched by conventional RF CW biasing.…”

Section: Introductionmentioning

confidence: 99%

“…DC pulse-biasing instead of RF biasing has been investigated recently in the etching of III-V compounds to etch III-V compounds more selectively over the photoresist and more anisotropically in addition to the advantage of no need for specific matching network, low heat generation during the etching, etc. 30) In this study, DC pulse biasing was also introduced in the etching of MTJ-related materials to explore the possibility in improving the etch characteristics of the MTJ-related materials such as CoFeB, CoPt, MgO and W using an optimized CO/NH 3 gas mixture and the etch characteristics were compared with those etched by conventional RF CW biasing.…”

Section: Introductionmentioning

confidence: 99%

A study on the etching characteristics of magnetic tunneling junction materials using DC pulse-biased inductively coupled plasmas

Yang

Jeon

Yeom

2014

The etching properties of magnetic materials composing the magnetic tunnel junction (MTJ) such as CoPt, MgO, CoFeB, and CoPt/MgO/CoFeB were investigated in DC pulse biased CO/NH 3 inductively coupled plasmas (ICPs) and their etch characteristics were compared with those etched by RF CW biased ICPs. The use of DC pulse biased ICPs instead of RF CW biased ICPs improved the etch selectivity of the MTJ materials over W and also decreased the residue on the surface of the etched materials possibly due to the more stable and volatile etch product formation during the DC pulse off time and the enhanced removal of the etch products by mono-energetic ions during the DC pulse on time. When MTJ materials masked with W were etched, more anisotropic etch profile could be also observed when the MTJ materials were etched with the DC pulse biasing of 60% duty percentage compared with those etched with RF CW biasing due to the decreased redeposition of etch products on the sidewall of the etched feature in addition to the enhanced etch selectivity over W.

“…As seen in the figure, our target requires a superior technique compared with present GaAs/AlGaAs optical devices such as PCs and vertical cavity surface emitting laser (VCSEL) systems. [9][10][11][12][13][14][15] Reports on this method are very limited and thus the etching mechanism has not been substantially discussed yet. 16) Recently, we have reported that the contaminant Al suppresses etching.…”

Section: Introductionmentioning

confidence: 99%

Over 1.5 µm Deep Dry Etching of Al-Rich AlGaAs for Photonic Crystal Fabrication

Kitabayashi

Mochizuki

Ishikawa

et al. 2013

We investigate inductively coupled plasma deep dry etching of Al0.8Ga0.2As for photonic crystal (PC) fabrication using the Cl2, BCl3, and CH4 mixture. On the basis of our previous work [M. Mochizuki et al.: Jpn. J. Appl. Phys. 50 (2011) 04DG15], we explore the deeper dry etching of the PC structure, investigating the impact of gas flow rate and chemical reactions. Increasing gas flow rate and process pressure resulted in deeper etching. These conditions increased the self-bias applied on the sample, which induced the sharpening of the air hole bottom and limitation of further deep etching because of the strong contribution of physical etching. The reduction of CH4 gas suppressed the sidewall passivation, counteracting the effect of the physical etching. As a result, we obtained a PC structure having air holes with a depth larger than 1.5 µm and a diameter of 120 nm.