ABRUPT AND ARBITRARY PROFILE FORMATION IN SILICON USING A LOW-KINETIC-ENERGY ION-BOMBARDMENT PROCESS

We have discovered that the carrier concentration in an epitaxial silicon film formed by the low-energy ion bombardment process is easily controlled by changing the ion bombardment energy during the film growth. While maintaining the perfect crystallinity of an epitaxial silicon layer grown at a temperature as low as 350 degrees C an arbitrary-shaped carrier concentration profile has been created in the film. Formation of box-shaped profiles as well as staircase-shaped profiles having very abrupt transitions is demonstrated. Formation of such arbitrary-shaped carrier profiles in an epitaxial layer is quite essential in the design of ultrasmall-dimension devices. The stability of carrier profiles against heat treatments also has been investigated.