A new fabrication process for uniform SU-8 thick photoresist structures by simultaneously removing edge bead and air bubbles

Abstract

This paper proposes a new SU-8 fabrication process to simultaneously remove edge bead and tiny air bubbles by spraying out edge bead removal (EBR) fluid over the entire surface of photoresist. In particular, the edge bead and air bubbles can cause an air gap between a film mask and a photoresist surface during UV exposure. The diffraction effect of UV light by the air gap leads to inaccurate and non-uniform SU-8 patterns. In this study, we demonstrate a simple method using EBR treatment to simultaneously eliminate the edge bead at the edge of wafer and tiny air bubbles inside SU-8. The profiles of thickness variation of SU-8 films with/without the EBR treatment are measured. The results show that the proposed EBR treatment can successfully remove the edge bead and air bubbles over the entire SU-8 films. The average pattern uniformity of SU-8 is improved from 50.5% to 11.3% in the case of 200 μm thickness. This method is simple and inexpensive, compared to a standard EBR process, because it does not require specialized equipment and it can be applied regardless of substrate geometry (e.g. circular wafer and rectangular slide glass).

Comparative study of soft thermal printing and lamination of dry thick photoresist films for the uniform fabrication of polymer MOEMS on small-sized samples

“…In this way, the edge beads can extend the boundaries, provided close contact is obtained between the sample and the surrounding pieces; however, this is only applicable to rectangular samples. Finally, advanced treatments proposed by Microchem TM , such as edge bead remover (EBR), significantly improve layer uniformity from 50% to 11.3% [15], although it can sometimes lead to de-wetting effects.…”

Maximizing derivable information from cytologic specimens for pathologic and molecular diagnostics

“…16,17 The channel, as constructed, measured 4.5 cm in length, 5 mm in width, and 100 mm in height. In the middle of the channel was a circular region designed for viewing that measured 1.5 cm in diameter.…”

Large scale three-dimensional simulations for thick SU-8 lithography process based on a full hash fast marching method

“…Inclined and vertical ultraviolet (UV) lithography of thick photoresists plays an important role in manufacturing novel and complex high aspect-ratio MEMS elements with low cost and high resolution [1][2][3][4][5][6]. For many years, lithography simulation has been employed to optimize the design of micron and sub-micron devices and related devices in integrated circuits (IC) field.…”