Profile and Morphology Control during Etching of SiC Using Electron Cyclotron Resonant Plasmas

Abstract

The profiles and surface morphologies of etched SiC can be effectively controlled using electron cyclotron resonant plasmas. When high bias (100 V) is applied to the substrate, etching is anisotropic and smooth surfaces result, with the exception of trenches which form at the base of the sidewall features. In contrast, etching at low bias (8 V) is more isotropic with no apparent trenching, but results in textured etched surfaces and jagged sidewall features. However, the etched surfaces and sidewall features can be smoothed by subjecting the samples to a high bias pretreatment prior to etching at lower bias. Etching isotropy is strongly dependent on both the applied bias and the proximity of the sample to the ECR source. A combination of high and low bias etching has been employed for micromachining cantilever structures from single‐crystal SiC.

Etching of 4H-SiC using a NF3 inductively coupled plasma

“…Fortunately, a similar phenomenon has been noticed as the bias power was varied at relatively large DC bias. 11,17 Those previous observations are similar to the current one because the DC bias at 150 W is much larger than the one at 50 W, as shown in Table II. This is further supported by the variations in the surface roughness as the bias power was increased from 100 W to 150 W, as shown in Table I.…”

“…The surface roughness considerably decreases by about 0.299 nm with increasing the bias power from 100 W to 150 W. This behavior contrasts with the one observed in C 2 F 6 /O 2 chemistry 10 but is similar to the one noticed in an electroncyclotron resonance CF 4 plasma. 17 Effect of the source power on the etch responses are contained in Table II. The source power effect was examined at two different bias powers, 50 W Other source power, pressure, and gas ratio were set to 800 W, 6 mtorr, and 0.6, respectively.…”

Etching profile of silicon carbide in a NF3/CH4 inductively coupled plasma

“…Microtrentching occurs at the base of the profile, as illustrated in Fig. 8, which is similar to previously observed ones [3,7,12,13]. The formation of microtrentching is typically attributed to enhanced ion bombardment by increased ion flux at the foot of the sidewall due to the depletion of ions impinging on the wall at low angles [14,15].…”

Comparison of F2 plasma chemistries for deep etching of SiC

“…[4][5][6][7][8][9][10][11][12][13] With the advent of high density plasma sources, including electron cyclotron resonance (ECR), inductively coupled plasma (ICP), and Helicon, much higher SiC etch rates have been reported. [14][15][16][17][18][19][20][21][22][23][24][25] The key advantage of these sources is decoupling of ion energy and ion flux, so that relatively low ion energies can be employed. This reduces the electrode sputtering problem and in addition the plasma chemistries for high density sources generally involve gases that do not A number of F 2 -based plasma chemistries (NF 3 , SF 6 , PF 5 , and BF 3 ) were investigated for high rate etching of SiC.…”