Insulator Ion Implantation Process
The formation of SiO2 by ion implantation occurs in the manner shown in the following figure
- The phases shown correspond to
- (a) Ions initially accumulate according to Gaussian distribution. Damage from implant amorphizes silicon in the region of highest impact.
- (b) Concentration reaches stoichiometric proportions to form SiO2.
- (c) Oxide layer grows outward, consuming silicon.
- (d) After annealing, damaged (amorphous) layers become polycrystalline.
Notice that, in order to form the abrupt interface between oxide and silicon, we need to implant a large dose of oxygen. This result can be seen in the chart below. Also notice that if the dose is too great, the surface crystalline layer can be lost.