Process and productivity improvements during high pressure photoresist outgassing

Beam neutralization during high current ion implantation has historically posed a challenge for process engineers. Minimizing dose errors may require significant implant process limits such as decreased beam currents and/or maximum pressure limitations, or the use of pressure compensation algorithms. Threshold Activated Dose Control (TADC), a new dose algorithm, can enhance high-pressure operation by using a constant, pressure-compensated beam current to control dosing when the pressure exceeds a predetermined threshold. With TADC, beam currents can be increased without running into pressure limitations and without added interruptions, which can lead to shorter implant times and increased throughput. In addition, the sensitivity of dose to the accuracy of the pressure compensation setting (PCOMP) can be decreased with TADC. As a consequence, repeatability and uniformity may be improved for these implants. This paper presents a description of the algorithm and system requirements. The method was introduced into a high-volume manufacturing environment and qualified with extensive device splits. Reductions in implant times of up to a factor of three were realized with no degradation in process performance.