Total-internal-reflection-based photomask for large-area photolithography

Shao-Kang Hung*, Kung Hsuan Lin, Cheng Lung Chen, Chen Hsun Chou, You Chuan Lin

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Photolithography has been widely implemented with a photomask in contact or in close proximity to the photoresist layer. The flatness of the substrates is a crucial factor to guarantee the quality of the entire patterned photoresist (PR) layer especially for large-area photolithography. However, some substrates, such as sapphire wafers, do not possess highly uniform thickness as silicon wafer does. In this work, we demonstrate that a flexible polydimethylsiloxane (PDMS) photomask with optical total-internal-reflection structure can effectively circumvent this problem for mass production. Different from conventional photomask that the light is blocked by the patterned reflective/absorbing materials, the distributions of light intensity on the PR is engineered by the geometric structure of the transparent PDMS photomask. We demonstrate that 4 in. patterned sapphire wafers can be successfully fabricated by using this PDMS photomask, which can be easily integrated into the present techniques in industry for mass production of substrates for GaN-based optoelectronic devices.

Original languageEnglish
Pages (from-to)39-44
Number of pages6
JournalOptics and Laser Technology
StatePublished - 1 May 2016

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