Raytheon Company

Hughes Aircraft Company

Santa Barbara Research Center

Joan K Chia

Charles A Cockrum

Kenneth Kosai

Robert P Ginn

Stephen H Propst

Chao Huang

James F Kreider

This invention pertains to a method for processing readout integrated circuits, and to a readout integrated circuit (10) that is processed in accordance with the method. The method includes a first step of providing a plurality of individual readout circuits each having a substrate (12) and at least one layer (14) constructed to have active circuitry that overlies a first surface (12a) of the substrate. Each of the readout integrated circuits has an associated amount of non-flatness or bowing due at least in part to a first force exerted on the substrate by the at least one layer of circuitry. A next step sorts the plurality of readout integrated circuits into a plurality of groups (A, B, C), wherein members of a group have a similar amount of non-flatness. A next step of the method determines, for each group, a thickness of compensating layer (18) and then applies the compensating layer on a second surface (12b) of the substrate so as to exert a second force on the substrate to counteract the first force and to reduce the amount of non-flatness. In a presently preferred embodiment of the invention the step of applying includes a step of sputtering a layer comprised of Si.sub.3 N.sub.4 upon the second surface. The step of sorting includes the steps of operating an interferometer to generate a pattern of fringes for indicating a degree of non-flatness of each of the readout integrated circuits; and counting the fringes and sorting the readout integrated circuits as a function of the number of fringes.

Readout backside processing for hybridization

A mercury-cadmium-telluride (HgCdTe) photoresponsive layer (14) having the composition Hg.sub.1-x Cd.sub.x Te is formed on a substrate (12) such that x increases from the surface (14a) of the photoresponsive layer (14) toward the substrate (12). This causes the bandgap in the photoresponsive layer (14) to increase from the surface (14a) toward the substrate (12), thereby urging minority carriers which are photogenerated in the photoresponsive layer (14) to move toward and be trapped at the surface (14a). Laterally spaced first and second ohmic contacts (16,18) are electrically connected to the photoresponsive layer (14) at a predetermined distance (z.sub.c) below the surface (14a) such that the photogenerated minority carriers trapped at the surface (14a) are urged away from the contacts (16,18) by the increasing bandgap. An electrically floating photoresponsive layer (24) of opposite conductivity type may be formed between the substrate (12) and the photoresponsive layer (14) to form a Heterojunction Interface Trap.

Photoresponsive device including composition grading and recessed

Metallic contacts to compound semiconductor devices which employ a native oxide for passivation are provided. The metallic contacts of the invention comprise at least two metal layers: a first layer making non-rectifying contact with the semiconductor surface and providing a diffusion barrier and a second layer thereon comprising an easily oxidizable metal. A low resistivity metal layer may optionally be interposed between the two metal layers for improved conductivity. The metallic contact is formed prior to passivation. The diffusion barrier layer prevents diffusion of potentially deleterious materials into the semiconductor, while exposed portions of the oxidizable metal form an insulating oxide during anodic passivation in an electrolyte. The insulating oxide prevents disruption of the electric field distribution in the electrolyte, thereby eliminating passivating oxide and device non-uniformities commonly encountered in the formation of prior art metallic contacts and providing more uniform semiconductor oxide thickness.

Anodizable metallic contacts to mercury cadmium telleride

Growing community of inventors

Santa Barbara, CA, United States of America

Joan K Chia