A novel solution on KrF pixel layer with thick photo resist (PR) by single exposure multi-focal imaging (SE MFI) technique

Zhenhai Yao; Lequn Jin; Yuhua Li; Maoqun Jiang; Fabin Huang; Min Fang; Xichen Sheng; Rongkuo Zhao; Michael Crouse; Chris Kaplan; Dongqing Zhang; Dongxiang Shi; Zhonghua Xu; Chaoqun Guo; Pieter Scheijgrond; Xiaoyang Jason Li; Stephen Hsu; Will Conley; Zhen Tang

doi:10.1117/12.2616830

26 May 2022 A novel solution on KrF pixel layer with thick photo resist (PR) by single exposure multi-focal imaging (SE MFI) technique

Zhenhai Yao, Lequn Jin, Yuhua Li, Maoqun Jiang, Fabin Huang, Min Fang, Xichen Sheng, Rongkuo Zhao, Michael Crouse, Chris Kaplan, Dongqing Zhang, Dongxiang Shi, Zhonghua Xu, Chaoqun Guo, Pieter Scheijgrond, Xiaoyang Jason Li, Stephen Hsu, Will Conley, Zhen Tang

Author Affiliations +

Proceedings Volume 12051, Optical and EUV Nanolithography XXXV; 1205109 (2022) https://doi.org/10.1117/12.2616830
Event: SPIE Advanced Lithography + Patterning, 2022, San Jose, California, United States

Abstract

Advancing technology nodes in CMOS Image Sensors (CIS) continues to drive a shrinking process to acquire higher resolution and low power consumption as well as more cost-effective production. With the sensor pixel size scaling down, a thicker photoresist (with aspect ratios greater than 10:1) is introduced to block high-energy implants with extremely localized implant profiles. Then double exposures/double focus (DE/DF) is applied to make sure the resist profile and process window is comparable or better. However, this process is a big challenge at high volume manufacturing (HVM) phase because of throughput loss. To recover it due to DE/DF, we invented SE MFI which uses two wavelengths (“colors”) generated by the KrF excimer laser to solve the problem. Due to the chromatic aberrations in the lens, the focal plane shift of different wavelength produces nearly the same result as DE/DF. However, the use of two-wavelengths brings some challenges. The first is the loss of image contrast and the second is the impact of chromatic aberrations across the slit which results in image shift and image asymmetry. In this work, we demonstrated that the use of ASML’s Tachyon KrF MFI source mask optimization (SMO) that can match the MFI SE process to DE/DF process of record (POR). We first used Tachyon Focus-Exposure Modeling plus (FEM+) to calibrate a DE resist model by using DE POR wafer data. Then we converted the DE model to a SE MFI model. At the end, we use the Tachyon MFI-SMO to optimize the SE MFI to match the DE/DF and MFI sidewall profiles through process window conditions at the center slit. We achieved making the MFI and DE/DF sidewall difference significantly smaller than other noises which can be measured on wafer at the center slit. We evaluated the chromatic aberration impact on through slit sidewall profiles also meet the specification. The through slit matching between MFI and DE/DF was further improved by through-slit mask optimization. This is done by inserting asymmetry sub resolution assist features (SRAFs). Tachyon Optical Proximity Correction plus (OPC+) can support full chip mask corrections for full-chip HVM. The above MFI technology including Tachyon optimization capability will be verified by wafer exposure via comparison between MFI and DE wafer results.

Conference Presentation

Citation Download Citation

Zhenhai Yao, Lequn Jin, Yuhua Li, Maoqun Jiang, Fabin Huang, Min Fang, Xichen Sheng, Rongkuo Zhao, Michael Crouse, Chris Kaplan, Dongqing Zhang, Dongxiang Shi, Zhonghua Xu, Chaoqun Guo, Pieter Scheijgrond, Xiaoyang Jason Li, Stephen Hsu, Will Conley, and Zhen Tang "A novel solution on KrF pixel layer with thick photo resist (PR) by single exposure multi-focal imaging (SE MFI) technique", Proc. SPIE 12051, Optical and EUV Nanolithography XXXV, 1205109 (26 May 2022); https://doi.org/10.1117/12.2616830

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available