Etching process for producing substantially undercut free silicon on insulator structures
AssigneePlasma-Therm LLC
InventorsJohn F. Donohue, David J. Johnson, Michael W. Devre
Life of this patent
Estimating the term…
Abstract
A method of anisotropically plasma etching a silicon on insulator substrate wherein undercutting is substantially eliminated by utilizing as a finishing etch step a reactive ion etching process wherein the ion density is reduced in order to limit ion charging through different size recesses in order to uniformly etch in a vertical direction.
Claims27
A method of preventing undercut at a silicon-insulator interface during etching of a silicon substrate comprising etching a silicon substrate by reactive ion etching employing plasma, wherein ion density is reduced, thereby providing a vertical etch of sidewalls formed during the etching.
A method of preventing undercut at a silicon-insulator interface during etching of a silicon substrate comprising:
- a) anisotropic plasma etching by contacting a reactive etching gas with the silicon to remove material from the surface of the silicon and provide etched surfaces;
- b) polymerizing and depositing at least one polymer forming compound on the exposed surfaces of the silicon thereby creating a temporary coating layer by introducing the compound into the plasma;
- and
- c) reactive ion etching having a reduced ion density of less than about 10.sup.9 ions/cm.sup.3, wherein reactive ions are provided in plasma for impinging on the surface of the silicon.
A method of etching that avoids undercut of a silicon substrate comprising, comprising reactive ion etching a silicon substrate at sufficient ion velocity, ion density, ion mass, bias, power and pressure to attain an ion density less than about 10 ions/cm.sup.3.
A method etching that avoids undercut of a silicon substrate comprising, etching a silicon substrate by reactive ion etching employing plasma at reduced ion density.
Dependencies are inferred from the claim text.