Kazuya Sugawa

Study of influence to transistor properties on the change of OPC pattern

Slight change of OPC pattern shape may influence transistor characteristics. So inputting the result of Litho- Simulation, Contour, to SPICE-simulator, we investigated the change of the transistor characteristic. First of all, we investigated the sensitivity of the transistor characteristics to OPC pattern change. We found that the difference of shape with Isolated, Dense pattern, and a different OPC tool caused difference after SPICE-simulation. In this investigation, we report focusing on the transient and DC analysis of transistor characteristics. Contour data was measured and averaged before input to SPICE and a change of transistor characteristic was able to be detected. We came to the conclusion that this investigation method is effective to check the influence of the transistor characteristics due to OPC pattern change. And we can adopt this method as one technique for deciding the applicability of the OPC tool and its upgrade, which were issues for MASK data processing.

Simulation method using the image filter method

We conducted an experiment to determine if the use of image filter method for simulation that calculates the distribution of light intensity on a wafer can reduce processing time in comparison to the use of the Fourier transform. The image filter table value is set by changing the value of Gaussian distribution. The image filter method was approximated with the light intensity of optical simulation that keeps accuracy within the range of the allowance. In this experiment, we examined the differences between the distributions calculated using the Fourier transform and the calculation time by varying the sizes of the image filter tables. For the experiment, we used pattern data having a line width that used in the most advanced technology. When the area of pattern data was wide, the experiment revealed that use of the image filter method reduced calculation time by approximately 50 percent or more in comparison to a simulation that used the Fourier transform. As we decreased the size of the image filter tables, the calculation time became shorter, but the differences from the distribution calculated using the Fourier transform became larger. We intend to study the possibility of simulation by expanding the area of pattern data and using the image filter method for simulation-based OPC.