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.

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