Sensitivity enhancement of chemically amplified resists and performance study using extreme ultraviolet interference lithography

Abstract

Extreme ultraviolet lithography (EUVL, λ ¼ 13.5 nm) is the most promising candidate to manufacture electronic devices for future technology nodes in the semiconductor industry. Nonetheless, EUVL still faces many technological challenges as it moves toward high-volume manufacturing (HVM). A key bottleneck from the tool design and performance point of view has been the development of an efficient, high-power EUV light source for high throughput production. Consequently, there has been extensive research on different methodologies to enhance EUV resist sensitivity. Resist performance is measured in terms of its ultimate printing resolution, line width roughness (LWR), sensitivity [S or best energy (BE)], and exposure latitude (EL). However, there are well-known fundamental trade-off relationships (line width roughness, resolution and sensitivity tradeoff) among these parameters for chemically amplified resists (CARs). We present early proof-of-principle results for a multiexposure lithography process that has the potential for high sensitivity enhancement without compromising other important performance characteristics by the use of a "Photosensitized Chemically Amplified Resist ™ " (PSCAR ™ ). With this method, we seek to increase the sensitivity by combining a first EUV pattern exposure with a second UV-flood exposure (λ ¼ 365 nm) and the use of a PSCAR. In addition, we have evaluated over 50 different state-of-the-art EUV CARs. Among these, we have identified several promising candidates that simultaneously meet sensitivity, LWR, and EL high-performance requirements with the aim of resolving line space (L/S) features for the 7-and 5-nm logic node , respectively] for HVM. Several CARs were additionally found to be well resolved down to 12-and 11-nm HP with minimal pattern collapse and bridging, a remarkable feat for CARs. Finally, the performance of two negative tone state-of-the-art alternative resist platforms previously investigated was compared to the CAR performance at and below 16-nm HP resolution, demonstrating the need for alternative resist solutions at 13-nm resolution and below. EUV interference lithography (IL) has provided and continues to provide a simple yet powerful platform for academic and industrial research, enabling the characterization and development of resist materials before commercial EUV exposure tools become available. Our experiments have been performed at the EUV-IL set-up in the Swiss Light Source (SLS) synchrotron facility located at the Paul Scherrer Institute (PSI).

Promising Lithography Techniques for Next-Generation Logic Devices

“…Some other new techniques including nanoparticle photoresists with high sensitivity have been reported [23][24][25][26]. Lately at the 2016 SPIE Advanced Lithography conference, a good amount of papers was presented demonstrating the substantial research on Photosensitized CARs [27][28][29][30][31]. Moreover, some approaches have been introduced to improve sensitivity, LWR and local CDU from many directions [32,33].…”

Progress in EUV resists towards high-NA EUV lithography

“…The rectangular green area is defined using the threshold values (BE< 35 mJ/cm 2 , and LER < 4.6 nm for HP 16 nm; BE < 50 mJ/cm 2 and LER < 5.2 nm for HP 14 nm) that we adopted to have a quantitative definition for selection of "resists with good performance" [10]. These values are not representing the industry targets but are the threshold values that we use for quantitative comparison.…”

“…EUV interference lithography (EUV-IL) has been used to evaluate resist performance [2,[5][6][7][8][9][10][11]. One good advantage of EUV-IL is that we use the coherent light from synchrotron with the wavelength λ = 13.5 nm, so the theoretical resolution limit of this technique is 3.5 nm [12], that is much higher than the EUV scanner with 0.33NA and the future high NA (0.55NA) [3].…”

Nanolithography: Status and challenges

“…Some approaches have been presented to achieve high resolution around hp10 nm [23]. Lately at the 2016 SPIE Advanced Lithography conference, a good amount of papers was presented demonstrating the substantial research on Photosensitized Chemically Amplified Resist [24][25][26][27][28]. Over the last few years some organization like CNSE of SUNY Polytech associated with SUNY Polytech SEMATECH have supported the investigation of EUV resist materials and various EUV resists evaluation [29][30][31].…”