US PATENT SUBCLASS 257 / 655
WITH SPECIFIED IMPURITY CONCENTRATION GRADIENT

Current as of: June, 1999
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257 /   HD   ACTIVE SOLID-STATE DEVICES (E.G., TRANSISTORS, SOLID-STATE DIODES)

655WITH SPECIFIED IMPURITY CONCENTRATION GRADIENT {2}
656  DF  .~> With high resistivity (e.g., "intrinsic") layer between p and n layers (e.g., PIN diode)
657  DF  .~> Stepped profile

DEFINITION

Classification: 257/655

WITH SPECIFIED IMPURITY CONCENTRATION GRADIENT:

(under the class definition) Subject matter wherein the active solid-state device includes at least one region of semiconductor material with a specified profile or gradient of impurity doping concentration.

(1) Note. Examples of impurity concentration gradients include reverse gradient profiles (i.e., wherein the doping concentration is lighter toward the semiconductor surface or away from a pn junction) or a radial concentration profile).

SEE OR SEARCH THIS CLASS, SUBCLASS:

101, for light emitting devices with specified dopant concentration or concentration profile.

219, through 221, for charge transfer field effect majority signal carrier devices with impurity concentration variations (e.g., in the device channel).

335, through 343, for short channel IGFETs with graded dopant concentration in the active channel region that decreases with distance from the source region.

548, for integrated circuits with pn junction isolation having at least three regions of alternating conductivity types with dopant concentration gradients decreasing from the surface of the semiconductor. 596, and 597, for a voltage variable capacitance device with specified dopant profile (e.g., retrograde dopant profile).

929, for a pn junction isolated integrated circuit with isolation walls having minimum dopant concentration at an intermediate depth in an epitaxial layer.