FEA thermal investigation on plasma etching induced heating during wafer thinning process

In this work, finite element analysis (FEA) was used to predict transient heating and temperature distribution on the wafer surface during plasma etching process as backgrind (BG) tape degradation after plasma stress relief was observed. The wafer surface temperature during plasma process was measured using temperature indicator strips and used as input temperature for FEA analysis. A series of parametric studies were performed to analyse the effect of different silicon thickness and different wafer contact on electro static chuck (ESC) to understand the temperature distribution during the plasma process. The thermal behaviour of BG tape was also characterised using differential scanning calorimetry (DSC). Perfect wafer contact on ESC predicted 99.1 degC after 0.1s. With presence of air gaps, temperature increases to 105 degC and based on DSC analysis, melting is likely to occur. Therefore FEA & DSC analysis has demonstrated to be a potential technique for BG tape selection