Effects of Reactive Ion Etching Parameters on Etching Rate and Surface Roughness of 4H-SiC

Zehong Wan; Enkang Cui; Shengtao Yu; Yu Lei; Chengqun Gui; Shengjun Zhou

doi:10.3788/LOP202158.1922002

Journals >Laser & Optoelectronics Progress >Volume 58 >Issue 19 >Page 1922002 > Article

Laser & Optoelectronics Progress
Vol. 58, Issue 19, 1922002 (2021)

Effects of Reactive Ion Etching Parameters on Etching Rate and Surface Roughness of 4H-SiC

Zehong Wan¹, Enkang Cui¹, Shengtao Yu², Yu Lei², Chengqun Gui¹, and Shengjun Zhou^1、2、*

Author Affiliations

¹The Institute of Technological Science, Wuhan University, Wuhan , Hubei 430072, China

²School of Power and Mechanical Engineering, Wuhan University, Wuhan , Hubei 430072, China

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DOI: 10.3788/LOP202158.1922002 Cite this Article Set citation alerts

Zehong Wan, Enkang Cui, Shengtao Yu, Yu Lei, Chengqun Gui, Shengjun Zhou. Effects of Reactive Ion Etching Parameters on Etching Rate and Surface Roughness of 4H-SiC[J]. Laser & Optoelectronics Progress, 2021, 58(19): 1922002 Copy Citation Text

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Schematic illustration of experimental flow (Step 1: 4H-SiC substrate cleaning; Step 2: photoresist spin coating; Step 3: exposure; Step 4: development; Step 5: coating; Step 6: lift-off; Step 7: RIE; Step 8: mask removing and 4H-SiC substrate cleaning)

Fig. 1. Schematic illustration of experimental flow (Step 1: 4H-SiC substrate cleaning; Step 2: photoresist spin coating; Step 3: exposure; Step 4: development; Step 5: coating; Step 6: lift-off; Step 7: RIE; Step 8: mask removing and 4H-SiC substrate cleaning)

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Schematic illustration of step height measurement. (a) Step height h1 between mask and 4H-SiC substrate after lift-off; (b) step height h2 between the mask and 4H-SiC etched surface after RIE etching; (c) step height h3 between 4H-SiC unetched surface and 4H-SiC etched surface after mask removal

Fig. 2. Schematic illustration of step height measurement. (a) Step height

h_{1}

between mask and 4H-SiC substrate after lift-off; (b) step height

h_{2}

between the mask and 4H-SiC etched surface after RIE etching; (c) step height

h_{3}

between 4H-SiC unetched surface and 4H-SiC etched surface after mask removal

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Fig. 3. SEM images of different photoresists after exposure and development. (a) S1818 photoresist; (b) AR-N4340 photoresist; (c) ROL-7133 photoresist; (d) AZ2070 photoresist

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Fig. 4. Influence of exposure mode on photolithography. (a) Schematic illustration of exposure; (b) optical microscopy image of graphic photoresist in micro-force contact exposure mode; (c) optical microscopy image of graphic photoresist in soft contact exposure mode

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Fig. 5. Optical microscopy images of patterned photoresist with different exposure time and development time.(a)‒(c) Exposure time is 5, 10, and 20 s, respectively, and development time is kept at 20 s; (d)‒(e) exposure time is kept at 20 s, and development time is 16 and 20 s, respectively

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Fig. 6. Optical microscopy images of etching masks obtained after coating and lift-off of 4H-SiC substrates with poor and good lithographic quality. (a) Poor lithographic quality; (b) good lithographic quality

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Fig. 7. SEM images of 4H-SiC substrate after etching. (a) C-face; (b) Si-face

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Fig. 8. Influence of etching time. (a)‒(c) Height difference

h_{3}

measured by step profiler; (d)‒(f) SEM images of SiC with etching time of 200, 400, and 600 s, respectively; (g) etching rate of 4H-SiC substrate; (h) etching rate of Ni mask; (i) RIE etching selection ratio of Ni to 4H-SiC

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Fig. 9. Schematic illustration of actually measured step height. (a) Step height

h_{1}

after lift-off; (b) step height

h_{2}

after RIE etching; (c) step height

h_{3}

after removal of mask

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Fig. 10. Influence of etching time after process improvement. (a) Etching rate of 4H-SiC substrate; (b) etching rate of Ni mask; (c) RIE etching selection ratio of Ni to 4H-SiC; (d)‒(f) SEM images of SiC after etching 200, 400, and 600 s, respectively

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Fig. 11. Effect of O₂ content on 4H-SiC etching rate and surface RMS roughness

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Fig. 12. Effect of chamber pressure on 4H-SiC etching rate and surface RMS roughness

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Fig. 13. Effect of RF power on 4H-SiC etching rate and surface RMS roughness