Silicon Production Applications of Ion Implantation

Ion implantation techniques have found a wide range of applications in the processing of semiconductors. This selective low temperature doping technique has been readily incorporated into the existing technology of silicon wafer fabrication for both discrete devices and integrated circuits. The development of reliable production equipment capable of providing higher doping rates has increased by several orders of magnitude the range of doses which can be implanted at production throughputs. Most applications take advantage of the compatibility with existing process techniques, such as photoresist masking, or make use of unique capabilities such as implanting through thin surface layers of silicon dioxide or silicon nitride. Precise dose and energy control result in better control of process variables, permitting yield optimization for various product specifications. As circuit complexity and performance have increased in LSI manufacturing, some products now receive 4 to 6 different implants at various stages in the process flow. Reproducibility for process control and reliable operation of the equipment in the production environment have become increasingly important.