Abstract:

Au microgratings with small pitches and high aspect ratios are desired for high-sensitivity X-ray interferometry imaging. We use Au bottom-up filling (BUF) in Si templates to realize high-aspect-ratio Au microgratings. Void-free BUF in low-aspect-ratio gratings is first demonstrated to show BUF progression, and the mechanism of bismuth-stimulated BUF is explained by simulations. Fine tuning of process parameters is needed as a function of grating feature sizes; void-free BUF becomes more challenging when the aspect ratio increases as truncated BUF can occur. Progress to void-free filling of gratings with 2.1-µm-wide and 150-µm-deep trenches (aspect ratio > 70) is reported.

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