Order of Multiple Implants in a Process Affects Results

Introduction

When an implant occurs there will be some level of damage to the crystal structure of the silicon. If this damage is not annealed out then any subsequent implant will have a different penetration depth compared with the crystal that has no damage. The reason this occurs is due to the crystallographic nature of silicon. This means that there are some “channels” along certain crystallographic directions where ions can move much more freely.

When damage to the crystal occurs the material becomes amorphous and these channels no longer exist. If these effects are not modelled or taken into account then significant error could result.