Exploration and prevention of photo resist burning in a high current ion implanter

The current generation of ion implanters an capable of beam currents as high as 20 mA of Arsenic. Although this represents a big improvement in the implanter´s through-put, often it can´t be utilized because the photo resist begins to bubble and burn at ~15 mA of beam current. Screening experiments were used to explore I-line and G-line type photo resists with different solvents. Various beam currents and beam energies were used to look at the different affects of resist burning. In all cases, the in-situ particle sensor was able to detect the resist burning events as soon as they began. A residual gas analyzer (RGA) also detected the resist burning events, in real-time, and captured the occurrence of a xylene peak in the worst cases. The case in which no resist burning was observed used a high temperature deep UV treatment and an optical edge bead removal process. This paper will discuss the characteristics of photo resist burning and the applications of deep UV treatment and edge bead removal to prevent it