Chemically Amplified Resist Approaches for E-beam Lithography Mask Fabrication
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Chemically Amplified Resist Approaches for E-beam Lithography Mask Fabrication J.R. Maldonado, Etec Systems, an Applied Materials Company, Hayward, CA; M. Angelopoulos, IBM TJ Watson Research Center, Yorktown Heights, NY; W. Huang, IBM Corp., Hopewell Junction, NY; R. L. Brainard and J. M. Guevremont, Shipley, Marlborough, MA; Z. Tan, IBM Corporation, San Jose, CA ABSTRACT This paper describes stable, high sensitivity (5-10 µC/cm2 at 50 kV) e-beam resist systems utilizing chemical amplification suitable for mask fabrication for device generations below 100 nm. In particular, two resist systems with improved performance for mask fabrication developed in a joint program by Etec, IBM and Shipley will be described: a Si- doped version of the IBM KRS-XE resist (now commercially available) developed at IBM Research, and a new MANA resist developed at Shipley. Commercialization issues for mask e-beam resists also will be discussed. INTRODUCTION The thrust by device manufacturers to extend optical lithography with wavelengths ± 2°C). To address this issue, one can either design a hot plate that has very small variation throughout the whole surface area or design a resist that can tolerate the large variation of hot plate temperatures. As reported before, KRS-XE appears to be extremely robust in rfegards to baking temperature. The improved KRS-XE formulation appears to retain the bake latitudes. As shown in Fig. 10, the contrast curves of KRS-XE between PAB of 90°C and 120°C are very close to each other. The CDs are basically constant within the same PAB range, as shown in the SEM pictures (Fig. 11) and CD vs. PAB temperature plot (Fig. 12). With PAB fixed at 110°C/60s, both the dose (Fig. 13) and CD (Figs. 14, 15) are insensitive to PEB temperature between the range of 90°C and 110°C and there is a small difference between PEB and no PEB. The PEB performance of etch improved KRS-XE makes hot plates with improved temperature uniformity unnecessary during resist processing.
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Contrast % Film Thickness Remaining
120 100 80
90 C 100 C 110 C 120 C
60 40 20 0 1
10
100
Dose (uC/cm2)
Fig. 10: Contrast curves of etch improved formulation (Si loading C) exposed at 75 kV with PAB temperatures from 90°C to 120°C (no PEB).
75 KeV exposure No PEB Develop 0.263N TMAH, 60 sec
Fig. 11: 100nm SEM images of etch improved formulation (Si loading C) exposed at 75 kV with PAB temperatures from 90°C to 120°C (no PEB).
Exposure Latitude CD of the 100nm L/S (nm)
130 90 C PAB: 18% 100 C PAB: 20%
120
110 C PAB: 18% 120 C PAB: 21%
Contrast: Varying PEB
110 100
90 C 100 C 110 C 120 C
90 80 14
15
16
17
18
19
20
21
22
1
Dose (uC/cm2)
10
100
Dose (uC/cm2)
Fig. 12: Exposure latitude plot (CD of the 100nm images vs. dose) of etch improved formulation (Si loading C) exposed at 75 kV with PAB temperatures from 90°C to 120°C (no PEB).
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Fig. 13: Contrast curves of etch improved formulation (Si loading C) exposed at 75 kV with PEB temperatures from 90°C to 120°C (PAB 110°C).
CD of the 100nm L/S
120 90 C PEB: 15%
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