Microwave Induced Plasma (MIP) is an advanced decapsulation tool developed by Jiaco Instruments. The goal of this thesis is to optimise the current MIP system. There are two directions: 1. Improve the etching rate. 2. Find selectivity between different materials (Si, SiO2, SiN). The experiments are divided into two parts in total, improved cavity and CF4-based MIP machine etching selectivity experiment. The cavity experimental results demonstrate that high input power is the route to optimising MIP efficiency. Etch experiments demonstrate that the CF4/O2 gas recipe is effective in achieving etch selectivity and that temperature is a key factor influencing these etch selectivities.