Vacancy-rich silicon for use with a gallium nitride epitaxial layer
AssigneeTaiwan Semiconductor Manufacturing Company, Ltd.
InventorsPu-Fang Chen, Ching Yu Chen
Life of this patent
Estimating the term…
Abstract
A manufacturing process is described to evaluate and select raw semiconductor wafers in preparation for epitaxial layer formation. The manufacturing process first produces a single crystal ingot during which a seed pulling velocity and temperature gradient are closely controlled. The resulting ingot is vacancy-rich with relatively few self-interstitial defects. Selected wafers can advance to a high-temperature nitridation annealing operation that further reduces the number of interstitials while increasing the vacancies. Substrates characterized by a high vacancy density can then be used to optimize an epitaxial layer deposition process.
Claims20
A method, comprising:
- forming a crystal ingot from a crystal melt by pulling a solid crystal from the crystal melt at a pulling velocity V, the crystal ingot having a central region and an outer radius;
- while forming the crystal ingot, adjusting a ratio of the pulling velocity V to an axial temperature gradient G(V/G), wherein adjusting the ratio V/G adjusts characteristics of self-interstitial defects that form at the outer radius and vacancy defects that form in the central region;
- selecting a vacancy-rich region of the crystal ingot, wherein the vacancy-rich region comprises an oxidation induced stacking fault ring;
- cutting vacancy-rich semiconductor wafers from the vacancy-rich region of the crystal ingot;
- and
- removing the oxidation induced stacking fault ring in the vacancy-rich semiconductor wafers.
A method, comprising:
- identifying vacancy-rich semiconductor wafers from among a group of semiconductor wafers, wherein a peripheral region of each of the vacancy-rich semiconductor wafers comprises an oxidation induced stacking fault ring;
- removing the oxidation induced stacking fault ring by applying an annealing process to the vacancy-rich semiconductor wafers;
- performing a nitridation operation that exposes the vacancy-rich semiconductor wafers to a nitrogen gas;
- and
- epitaxially growing gallium nitride on the annealed vacancy-rich semiconductor wafers.
A method, comprising:
- forming a crystal ingot from a crystal melt by pulling a solid crystal from the crystal melt at a pulling velocity V, wherein the crystal ingot comprises a central region and an outer radius;
- while forming the crystal ingot, adjusting a ratio of the pulling velocity V to an axial temperature gradient G, wherein adjusting a ratio of the pulling velocity V to the axial temperature gradient G (ratio V/G) controls self-interstitial defects that form at the outer radius and vacancy defects that form in the central region;
- determining a region of the crystal ingot that is vacancy-rich;
- cutting vacancy-rich wafers from the vacancy-rich region of the crystal ingot;
- evaluating the vacancy-rich wafers against a set of selection criteria;
- and
- removing interstitials in the vacancy-rich wafers.
Dependencies are inferred from the claim text.