One or more techniques or systems for ion implantation are provided herein. A pressure control module is configured to maintain a substantially constant pressure within an ion implantation or process chamber. Pressure is maintained based on an attribute of an implant layer, pressure data, feedback, photo resist (PR) outgassing, a PR coating rate, a space charge effect associated with the implant layer, etc. By maintaining pressure within the process chamber, effects associated with PR outgassing are mitigated, thereby mitigating neutralization of ions. By maintaining charged ions, better control over implantation of the ions is achieved, thus allowing ions to be implanted at a desired depth.