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. 2021 Feb 17;11:3997. doi: 10.1038/s41598-021-83546-w

Figure 2.

Figure 2

Scanning electron micrograph of TSV holes (a) and trenches (b) fabricated with the optimized deep reactive ion etching. The width of the hole presents non-negligible bowing effect, going from a minor diagonal size of 1 µm at the top, ~ 1.15 µm in the middle and 0.8 µm at the bottom. Scanning electron micrograph of the Michelangelo-processed TSV hole with an AR of 28:1 (c). After KOH etching, bowing in drastically reduced, giving a slightly wider but constant 1.1 µm minor diagonal width at the top and middle of the TSV, dropping to 1 µm at the bottom. Particular of the surface roughness of the TSV after Michelangelo process (d).