Orthogonal Functional Method for Optical Proximity Correction of Thermal Processes in Optical Lithography

Abstract

The patterning of very small features is a difficult challenge for current lithography technology. The thermal process is an easy and simple solution involving no any additional processes. This process is one of extension techniques for 248 nm KrF and 193 nm ArF lithography equipment and chemically amplified resists (CARs). However, thermal effects are severe, thus, more critical approaches are needed for small pattern formation. In this paper, thermal processes are described and modelled for evaluating property changes in 248 and 193 nm CARs. The simulated results agree well with experimental results. Those processes can be used to shrink not only contact hole patterns but also space patterns. For the optical proximity correction (OPC) of thermal effects, an orthogonal functional method is introduced. These orthogonal functions depend on pattern types such as contact holes and spaces. By using this method, underbaked postexposure bake and thermal reflow are performed for the below-45-nm contact hole pattern for a 248 nm KrF CAR and the 32 nm contact hole pattern for a 193 nm ArF CAR. Thus, an orthogonal functional method is useful for carrying out the OPC for thermal effects.

Sensitivity of Process Parameters on Pattern Formation of Litho–Cure–Litho–Etch Process

“…During the curing process, [10][11][12]27,28) the thermal-shrink trace can be modelled as a surface evolution of pattern profile depending on thermal rates. Since the curing temperature is below the glass transition temperature of resist, the curing phenomena with the low-dissolution-rate is…”

Advanced Lithography Simulation for Various 3-Dimensional Nano/Microstructuring Fabrications in Positive- and Negative-Tone Photoresists

“…[7][8][9] This simulator is a scale-up of the macroscale lithography simulator. In moving-mask lithography, various profile shapes correspond to various aerial images.…”

“…The simulation results of the negative CAR and the positive CAR were the aerial images, the PAG concentrations after the exposure process, the cross-linked polymer concentrations after PEB, the dissolution rate concentrations for the development, and the pattern profiles. [6][7][8][9] The simulation results in Figures 3(1f), (1h), (2f), and (2h) agree well with the experiment results for the 75.5-nm L/S pattern profile in Figure 3(1e), 11 the 20-m L/S pattern profile in Figure 3(1g), 12 the 75-nm L/S pattern profile in Figure 3(2e), 13 and the 10-m L/S pattern profile in Figure 3(2g), 14 respectively. For the 75.5-nm (L/S = 1:1) pattern formation in Figures 3(1e) and (1f), the experiment conditions that corresponded to the simulation conditions were the 193-nm wavelength, the 90-nm ARC thickness, the 210-nm resist thickness, the 6% attenuated phase-shifting mask (Att-PSM), the 0.75 numerical aperture (NA), the annular illumination with the outer 0.89 and the inner 0.55 , the 26.2-mJ/cm 2 exposure dose, the soft bake (SB) at 105 C within 60 sec, PEB at 105 C for 60 sec, and development for 60 sec.…”

Analysis of irradiance distribution in optical proximity printing of micro annulus apertures

“…Similar phenomenon was also observed in other lithography processes and various methods were investigated to control or to correct such errors. [13][14][15][16][17][18][19][20][21][22][23][24][25] Nevertheless, such effect results in distortion of pattern in the micro fabrication process. It is therefore an important issue to investigate the distortion of pattern transfer in the proximity printing process.…”