Inductively coupled plasma etching of bulk, single-crystal Ga2O3

Abstract

High ion density dry etching of bulk single-crystal β-Ga2O3 was carried out as a function of source power (100–800 W), chuck power (15–400 W), and frequency (13.56 or 40 MHz) in inductively coupled plasma (ICP) systems using Cl2/Ar or BCl3/Ar discharges. The highest etch rate achieved was ∼1300 Å min−1 using 800 W ICP source power and 200 W chuck power (13.56 MHz) with either Cl2/Ar or BCl3/Ar. This is still a comfortably practical set of conditions, where resist reticulation does not occur because of the effective He backside cooling of the sample in the tool and the avoidance of overly high powers in systems capable of 2000 W of source power. The etching is ion-assisted and produces anisotropic pattern transfer. The etched surface may become oxygen-deficient under strong ion-bombardment conditions. Schottky diodes fabricated on these surfaces show increased ideality factors (increasing from 1.00 to 1.29 for high power conditions) and reduced barrier heights (1.1 on reference diodes to 0.86 eV for etched surfaces). This electrically active damage is dependent on ion energy and flux during the etching. An obvious strategy is to reduce plasma powers toward the end of an etch sequence to reduce the disruption to the Ga2O3 surface.

Control and understanding of metal contacts to β-Ga2O3 single crystals: a review

“…While fabricating Ga 2 O 3 based devices, plasma treatments are used in deep etching for patterning, surface cleaning, resist/dielectric layer removing. In those cases, the plasma-induced damage is unavoidable, which degrades the device performance [48,58,143,144]. Thus, an additional process for minimizing the plasma-induced surface damage is crucial to realize suitable device performance.…”

Synergistic properties of β-Ga2O3 nanowire arrays

“…Growing large-scale arrays of β-Ga2O3-based cylindrical structures with uniform morphology is still a huge challenge. At this point, there are few reports on the fabrication of β-Ga2O3 nanowire arrays by inductively coupled plasma etching [19][20][21][22][23][24][25][26][27]; the nanowires synthesized using the chemical vapor deposition technique using hydrogen [28]; the monoclinic, vertically oriented β-Ga2O3 nanowires obtained by hydrothermal method and annealed [29] (Fig. 1).…”

A Selective Etching Route for Large-Scale Fabrication of β-Ga2O3 Micro-/Nanotube Arrays

“…At present, the inductively coupled plasma (ICP) etching technology for the preparation of GaN nanowire (NW) arrays is mature, but there are few reports on the preparation of β-Ga 2 O 3 NW arrays by ICP etching. The existing reports mainly study the etching process conditions of β-Ga 2 O 3 films and single crystal [18][19][20]. The etching behavior of Ga 2 O 3 is completely different from that of GaN, more similar to Al 2 O 3 [21].…”