2015
DOI: 10.1116/1.4936112
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Deep germanium etching using time multiplexed plasma etching

Abstract: There is a growing need for patterning germanium for photonic and photovoltaics applications. In this paper, the authors use a time multiplexed plasma etch process (Bosch process) to deep etch a germanium substrate. They show that germanium etching presents a strong aspect ratio dependent etching and that patterns present scallops mostly on the upper part (aspect ratio below 0.8). Passivation layers are formed during the passivation step by neutrals' deposition and are reinforced during the etching step by the… Show more

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Cited by 13 publications
(11 citation statements)
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“…The cell singulation occurs by means of plasma etching through the 170‐μm active wafer (Figure 1F). The etching is performed using a Bosch process that consists in alternating etching steps (13 s, SF 6 /O 2 ) and passivation steps (7 s, C 4 F 8 ) for 45 min (average etch rate is >3.8 μm/min for 20‐μm‐wide trenches) 16 . The SiO x layer acts as an etch‐stop layer and can be removed by etching after the cell singulation occurs in case the front‐contacted cells are used as stand‐alone devices.…”
Section: Fabrication and Characterization Methodsmentioning
confidence: 99%
“…The cell singulation occurs by means of plasma etching through the 170‐μm active wafer (Figure 1F). The etching is performed using a Bosch process that consists in alternating etching steps (13 s, SF 6 /O 2 ) and passivation steps (7 s, C 4 F 8 ) for 45 min (average etch rate is >3.8 μm/min for 20‐μm‐wide trenches) 16 . The SiO x layer acts as an etch‐stop layer and can be removed by etching after the cell singulation occurs in case the front‐contacted cells are used as stand‐alone devices.…”
Section: Fabrication and Characterization Methodsmentioning
confidence: 99%
“…Then, an antireflective coating (ARC) made of SiNXHY/SiOXHY is deposited by plasmaenhanced chemical vapor deposition (PECVD). Besides increasing optical absorption of the cell, such ARC permits a passivation effect, which can limit perimeter recombination rate [9]. The ARC is then opened on metallization to access the electrical contacts.…”
Section: Devices Fabricationmentioning
confidence: 99%
“…The contact layer was etched using a NH 4 OH/H 2 O 2 /H 2 O solution and the samples were singulated either by full saw-dicing (reference samples, samples with holes, and one sample with isolation area etched by plasma) or plasma etching (one sample with isolation area etched by plasma). In the latter case, 125 µm of germanium is etched using a time multiplexed plasma etching process with 60 cycles of SF 6 /O 2 and C 4 F 8 plasmas to mimic a complete dicing by plasma etching while avoiding exposing the back side metal to the etching process [5]. To limit the surface recombination, a last step was done on the cells with via holes.…”
Section: Methodsmentioning
confidence: 99%