Masking Properties of Silicon Dioxide

• One of the most important properties of silicon dioxide is its ability to mask impurities during high-temperature diffusion.

• The diffusivities of antimony, arsenic, boron and phosphorous in silicon dioxide are all orders of magnitude smaller than their corresponding values in silicon. Thus silicon dioxide can be used effectively to mask these elements.

• Relative deep diffusion can take place in unprotected regions of silicon, whereas no significant impurity penetration will occur in regions covered by silicon dioxide.

Fig. 4 Diffusion masking oxide. [3]