Ford Microelectronics, Inc.

Other

David G McIntyre

Zachary J Lemnios

Dennis A Williams

Milton Feng

Robert Kaliski

Chung-Lim Lau

Chris R Ito

A (GaAs-resident) application specific monolithic microwave integrated circuit (ASMMIC) is fabricated through the use of footprints that include a portion of the metallization through which the circuit components within the wafer are to be interconnected. The metallization is a three layers structure, the first two layers of which include strategically arranged reactance circuit components (MIM) capacitors. A first of the three metal layers is formed on a first surface of the substrate which contains a plurality of semiconductor device regions and conductive material for ohmic contact to the regions, so that portions of the first metal layer are in ohmic contact with the conductive material. The first metal layer provides the bottom plate of the MIM capacitors. A dielectric layer, which serves as the dielectric insulator of the MIM capacitors, is formed on second portions of the first metal layer. A second, intermediate metal layer is selectively formed on the second portions of the first metal layer, to provide top plate segments of MIM capacitors. Personalization of the footprint is effected by an air bridge metal layer interconnecting the first and second metal layers and thereby semiconductor device regions of the semiconductor structure with capacitive reactance elements formed by the first and second metal layers.

Three metal personalization of application specific monolithic microwave

`Unintentionally` doped P type GaAs is grown on silicon by a metal organic chemical vapor deposition process in which the molecular ratio of arsenic to gallium in the growth ambient is reduced to a value that is sufficiently low to cause the creation of donor (As) site vacancies in the grown GaAs layer, which become occupied by acceptor (carbon) atoms in the metal organic compound, thereby resulting in the formation of a buffer GaAs layer having a P type majority carrier characteristic. Preferably, the silicon substrate has its growth surface inclined from the [100] plane toward the [011] direction is initially subjected to an MOCVD process (e.g. trimethyl gallium, arsine chemical vapor deposition) at a reduced temperature (e.g. 425.degree. C.) and at atmospheric pressure, to form a thin (400 Angstroms) nucleation layer. During this growth step the Group V/Group III mole ratio (of arsenic to gallium) is maintained at an intermediate value. The temperature is then ramped to 630.degree. C. and gas content adjusted to reduce the V/III mole ratio to a value less than 5.0, so as to grow a buffer layer of GaAs is grown on the nucleation layer. Because the molecular ratio of arsenic to gallium in the metal organic/arsine ambient is at a substantially reduced value, the resulting GaAs buffer layer tends to be depleted of arsenic atoms at numerous crystal sites, which allows for the substitution of acceptor (carbon) atoms from the metal organic compound, so that the buffer GaAs layer is P type.

Growth of P type Group III-V compound semiconductor on Group IV

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Colorado Springs, CO, United States of America

David G McIntyre