Proximity effect (electron beam lithography)

About: Proximity effect (electron beam lithography) is a research topic. Over the lifetime, 940 publications have been published within this topic receiving 8508 citations.

Softbake and Post-exposure Bake Optimization for Process Window Improvement and Optical Proximity Effect Tuning

Abstract: We have shown that process effects induced by extending the softbake (SB) and post-exposure bake (PEB) temperature in the process flow of chemically amplified photoresists can lead to significant improvements in depth-of-focus (DOF) and exposure latitude (EL) and small geometry printing capability (resolution). Through careful optimization of SB and PEB temperature, dense line and space structures of 160 nm and below can be printed with substantially big process margin, using binary masks and 248 nm lithography under the half annular illumination mode. Besides, we have also shown that the optical proximity effect, namely the non-linearity, proximity bias and line-end shortening in specific is tunable by changing the SB and PEB temperatures. The main objective of this study is to demonstrate how, using 248 nm lithography with binary masks and with a moderate resolution enhancement technique (RET); the process latitude can be improved besides minimizing the impact from optical proximity effect.

Advanced Mask Process Modeling for 45-nm and 32-nm Nodes

Abstract: As tolerance requirements for the lithography process continue to shrink with each new technology node, the contributions of all process sequence steps to the critical dimension error budgets are being closely examined, including wafer exposure, resist processing, pattern etch, as well as the photomask process employed during the wafer exposure. Along with efforts to improve the mask manufacturing processes, the elimination of residual mask errors via pattern correction has gained renewed attention. The portfolio of correction tools for mask process effects is derived from well established techniques commonly used in optical proximity correction and in electron beam proximity effect compensation. The process component that is not well captured in the correction methods deployed in mask manufacturing today is etch. A mask process model to describe the process behavior and to capture the physical effects leading to deviation of the critical dimension from the target value represents the key component of model-based correction and verification. This paper presents the flow for generating mask process models that describe both shortrange and long-range mask process effects, including proximity loading effects from etching, pattern density loading effects, and across-mask process non-uniformity. The flow is illustrated with measurement data from real test masks. Application of models for both mask process correction and verification is discussed.

Method and apparatus for electron beam lithography

Abstract: PROBLEM TO BE SOLVED: To precisely correct the radiation amount for removing the effect of the proximity effect while avoiding degradation of the throughput. SOLUTION: An electron beam lithographic apparatus draws a graphic on a sample by directly radiating an electron beam to the same region on the sample. An interpolation circuit 55 determines the radiation time of the electron beam for drawing the graphic. A shot time conversion circuit 56 determines the shot time for each shot so that the remaining time obtained when dividing the radiation time by the number of shots is compensated with a single shot. COPYRIGHT: (C)2004,JPO

The effect of acceleration voltage on linewidth control with a variable‐shaped electron beam system

Abstract: Variable‐shaped electron beam systems offer high throughput in electron beam lithography. However, excessive heating of resist on low thermal conductivity substrates and the proximity effect act to degrade the linewidth of photomasks. The effect of acceleration voltage (15, 20, and 30 kV) and electron beam size (0.5–4 μm⧠) linewidth was investigated in positive (RE5000P) and negative (CMS) resist. An acceleration voltage of 20 kV is seen to be suitable for mask fabrication in patterns with features larger than 1 μm from the viewpoint of linewidth accuracy and pattern quality.

An electron emissive mask for an electron beam image projector, its manufacture, and the manufacture of a solid state device using such a mask

Abstract: The mask part 41 includes a substrate 1, a patterning means 40 and a photoemissive layer 6. The patterning means 40 includes a mask pattern 2, 3 of apertures 3 and masking areas 2 and a modifying layer 4. Ultraviolet radiation 56 is patterned by patterning means 40 before effecting electron emission 60 from the photoemissive layer 6. There is electron emission from over the apertures 3 and the masking areas 2 as the masking areas are partially transparent to incident ultraviolet radiation. The ultraviolet transmitted by the apertures and the masking areas is modified in intensity dependent on the thickness R of the modifying layer. The resuting electron emission 60 is in a patterned beam which forms a proximity effect corrected electron image of the mask pattern in the electron sensitive resist layer 63. The masking areas 2 of chromium and the modifying layer 4 of resist may be made by modifications of known methods of chromium deposition and resist exposure and development. The use of the mask in the manufacture of a solid state device allows a single exposure of a resist layer 63 to form a proximity effect corrected image of the mask pattern 2, 3 in the resist layer 63.