A new self-limiting process for the production of thin submicron semiconductor films

Abstract

This paper describes a new anodic etching technique for the fabrication of device quality, self-limited, thin submicron semiconductor films. The technique relies upon the creation of a thin slightly damaged surface layer in the semiconductor by low dosage ion implantation. Evidence is presented to show that the lifetime of holes in this layer is drastically reduced causing the etching rate to decrease by a factor of several thousand when the damaged layer is exposed to the anodic etching solution.

The Fabrication of Thin, Freestanding, Single‐Crystal, Semiconductor Membranes

“…Attempts to bypass these problems by starting with a heavily n-type doped wafer and implanting a p-type impurity into it to create a thin, compensated, surface region that was effectively, lightly doped led, in 1982, to the discovery of another selflimited anodic etching technique (76). Attempts to bypass these problems by starting with a heavily n-type doped wafer and implanting a p-type impurity into it to create a thin, compensated, surface region that was effectively, lightly doped led, in 1982, to the discovery of another selflimited anodic etching technique (76).…”

“…Damage limited etching.--One of the problems that prevented van Dijk and de Johnge's technique from being used to produce membranes of silicon less than 1 ~m thick was that outdiffusion and autodoping phenomena prevented the growth of suitably thin, lightly doped epitaxial layers on heavily doped substrates. Attempts to bypass these problems by starting with a heavily n-type doped wafer and implanting a p-type impurity into it to create a thin, compensated, surface region that was effectively, lightly doped led, in 1982, to the discovery of another selflimited anodic etching technique (76). The authors attempted to etch an implanted silicon wafer that had not been annealed, and found that the dissolution rate of the implanted layer was markedly less than that of the unimplanted material (see Fig.…”

“…Membranes can be made from wafers implanted with either donor or acceptor ions, or ions that are entirely neutral in the semiconductor, such as silicon ions into a silicon wafer. Moreover, the final thickness of the membrane is related to the projected range of the implanted ions: in silicon, preliminary measurements (76) indicated that the membrane thickness was approximately equal to the projected range, while in GaAs, it was approximately twice the projected range of the implanted ion (77).…”