Photoresist adhesion effect of resist reflow process

Abstract

Making a sub-100 nm contact hole pattern is one of the difficult issues in semiconductor process. Compared with another fabrication process, resist reflow process is a good method to obtain very high resolution contact hole. However it is not easy to predict the actual reflow result by simulation because very complex physics and/or chemistry are involved in resist reflow process. We must know accurate physical and chemical constant values and many fabrication variables for better prediction. We made resist reflow simulation tool to predict approximate resist reflow as functions of pitch, temperature, time, array, and so on. We were able to see the simulated top view, side view and the changed hole size. We used Navier-Stokes equation for resist reflow. We had varied the reflow time, temperature, surface tension, and 3-dimensional volume effect for old model. However the photoresist adhesion is another very important factor that was not included in the old model. So the adhesion effect was added on Navier-Stokes equation and found that there was a distinctive difference in reflowed resist profile and the contact hole width compared to the case of no adhesion effect.