Harris Miller

Principal Engineer for New Product Development at MicroChem Corp

Harris Miller is Principal Engineer for New Product Development at MicroChem Corp, where he brings decades of experience to the design and fabrication of image sensors, optoelectronics, LEDs, MEMS and semiconductor devices. Harris graduated from the Rochester Institute of Technology with a Bachelor of Science in Imaging Science and from the University of Lund in Sweden with a Licentiate of Technology in Chemical Engineering. Harris is also an American Fulbright Scholar and the recipient of a Small Business Innovative Research grant for Compliant, Space-based Optics. Harris currently holds many patents for the design of photoresists, CMOS and CCD image sensors, microlenses and a wide variety of wafer processing techniques.

Abstract: High Resolution DRIE and Ultra-high Aspect Ratio Plating Resist for TSV and 3D Packaging

The demands for higher density through silicon vias (TSV) for chip-scale packaging are pushing the limits of photoresists for deep reactive ion etching (DRIE). Although thermal oxide masks have been the standard for DRIE etching, photoresists are now replacing oxide in many TSV applications. For a photoresist to perform well in a Bosch-etch process it must tolerate prolonged exposures to fluorine plasma, ion bombardment and produce a deep silicon etch in the range of 400-625 μm or more. Often, thick positive i-line photoresist coatings are used to control this etch step. However, few resists can produce a high-aspect ratio pattern with straight sidewalls from either contact or reduction stepper exposures. Straight photoresist sidewalls are crucial for transferring a high resolution pattern into the silicon substrate, to avoid a heavy positive etch bias and etched sidewall degradation. This paper will explore the use of KMPR as an alternative to conventional i-line photoresists. Critical performance factors of this chemically amplified, i-line resist are metal-ion free aqueous development, high resolution DRIE processing for deep Si trenches as well as its use as a plating form for up to 9:1 aspect ratio plated structures. Results will be presented showing 980um deep TSV etched with only a 10um film thickness of KMPR and high resolution, 1.6 um diameter, 100:1 aspect ratio Si trenches produced with only a few microns of KMPR photoresist. Additional advantages of this film will be highlighted, including its post etch or post plating removal.