Simulation of resist exposure and development on topographic substrates

The application of software tools in the development of new processes and novel device structures has become a dominant feature in the microelectronics industry. The use of these tools enables technologists to advance optical lithography to submicron levels of IC fabrication, i.e. 64 Mbit DRAMs. In this work, 2D modelling and simulation of optical microlithography on topographic substrates is investigated. A new program called SLITS (simulation lithography on topographic.substrates) has been developed which calculates 2D latent and relief images. The latent image is calculated by solving the Helmholtz equation using finite element analysis. To generate the relief images, new boundary detection and air/resist movement algorithms, which are not features of any traditional lithographic simulator have been designed and implemented. Relief images produced by SLITS and an earlier program ANKAN for a resist on planar substrate are compared and analysed. We also have investigated notching effects in a photoresist layer on non-planar substrates and the effect of prebake temperature on linewidth.