Characterization of photoresist films exposed to high-dose implantation conditions

Alternative approaches are now required to fulfill the strict requirements of photoresist (PR) dry strip process after high-dose implantation. A better understanding of the PR degradations induced by the ion bombardment during the implantation is thus required. In this study, in-depth characterizations of PR films after arsenic and phosphorus-high-dose implantation have been made. The influence of the dopant species (As or P) as well as the implantation energy has been investigated. The experimental results have then been confronted to simulations performed with stopping and range of ions in matter (SRIM). The experimental results show the formation of a “crust layer” enriched in carbon and depleted in oxygen and hydrogen whose density, hardness, and elastic modulus are higher than the nonimplanted PR (pristine). SRIM simulations confirm that the PR degradation is mainly due to crosslinking phenomenon. Chemical analyses have revealed that the dopants are present in their elemental and oxidized forms in the PR and that they are also linked to the PR carbon atoms. The knowledge of the dopants' chemical environment is key information to understand the presence of residues after dry strip processes and develop alternative processes to avoid their formation.