A COMPARISON OF THE REACTION-DIFFUSION KINETICS BETWEEN POLYMER AND NON-POLYMER PHOTORESISTS

 

Shuhui Kang, Kristopher Lavery, Kwang-Woo Choi,Vivek M. Prabhu,

Wen-li Wu, Eric K. Lin

 

Presenter: Shuhui Kang

Mentor: Vivek M. Prabhu

Polymers Division, MSEL

100 Bureau Dr., Stop 8541

Bldg 224, Rm. A327

Phone: (301)-975 4602

Fax: (301) 975-3928

Email: skang@nist.gov

 

Sigma Xi Member:  Yes

Category:  Materials

 

Abstract

Over the past 30 years, microelectronics technology has been one of the main driving forces responsible for the continuous prosperity of U. S. economy.  The primary driver for continued advances in this technology is through the advancement of photolithography and electronics material known as photoresist, which is used to “print” a pre-designed pattern on silicon chips. Increased pattern resolution results in smaller features and faster and cheaper computer chips.  The main obstacle limiting pattern transfer as the feature size becomes smaller and smaller is the line-edge-roughness (LER) produced in photoresists which are traditionally polymeric materials. It has been recently postulated that sub-22 nm photolithography with polymeric photoresists has reached a materials design barrier due to its large molecular weight and distribution.  Instead using a monodispersed low molecular weight photoresist material called “molecular glass” could provide a smaller LER because of its smaller pixel size compared to the radius of gyration of the polymer photoresist, therefore produce better feature fidelity and higher resolution in the same lithographic process. In this work, the deprotection reaction-diffusion kinetics, a critical issue related to LER, was studied for both polymeric photoresist and molecular glass photoresist and a comparison was made between them to elucidate effects of molecular architecture on photoresist performance.   We have determined the mechanism of reaction, photoacid trapping behavior, and diffusivity by measuring and comparing the reaction kinetics parameters as a function of temperature.  These results provide a quantitative approach to predict line-space features, crucial for design for resolution-enhancement features.