A voltage variable capacitor (10) has as the base substrate a silicon wafer with a layer of high resistivity semiconductor material on top of the substrate. An insulating layer (16) of a metal oxide having a dielectric constant greater than the dielectric constant of the semiconductors (12), such as zirconium titanate, is formed on top of the high resistivity layer, and a metal electrode (18) is formed on the insulating layer (16). When the electrode is energized, a depletion layer (20) is formed in the high resistivity layer. By varying the voltage applied to the electrode, the capacitance of the device is altered.

Voltage variable capacitor.

A semiconductor device (10), comprising a semiconductor substrate (12) having a layer of semiconductor material (14) deposited, coated or grown epitaxially as a single crystal or polysilicon on the surface of the substrate. The layer of material is also a semiconductor material, having a higher resistivity than the substrate it is deposited on. A dielectric layer (16) of a metal oxide is formed on the high resistivity layer (14), which is then covered with an amorphous layer (18) of a metal oxide dielectric. Zirconium titanate may be used as a metal oxide dielectric layer. A metal electrode (20) is formed on the amorphous layer (18) to form a Metal Insulator Semiconductor device. In an alternative configuration, the amorphous layer (18) may instead be placed between the high resistivity layer (14) and the dielectric layer (16), or a second amorphous layer (22) may be added between the high resistivity layer and the dielectric layer. When the device is electrically energized, a depletion region is formed in the high resistivity layer, creating a voltage variable capacitor.

Voltage variable capacitor having amorphous dielectric film

A zener diode in which the anode region of a first conductivity material is formed by diffusion in a semiconductor body, a cathode region of a second conductivity material is formed by diffusion in the semiconductor body, and the two regions are bridged by a third region extending through the two regions, the third region being a shallow layer of ion implanted doping material of said first conductivity type. In one embodiment, the anode and cathode regions are spaced-apart; in a second embodiment the cathode region is formed within the anode region. The ion implanted layer has a concentration that peaks below the surface, thus establishing the breakdown point for the avalanching of the zener diode below the surface and removed from surface contaminants such as found in the oxide surface layer.

Zener diode incorporating an ion implanted layer establishing the breakdown point below the surface

A semiconductor varactor diode of the hyperabrupt junction type, typically having a PNN+ configuration, is disclosed. The impurity concentration in the intermediate N-type portion is grown in by the molecular beam epitaxy process to provide the hyperabrupt profile. Also, the N-type background doping in the P-type zone is minimized by the same epitaxial process to reduce the level of impurity compensation needed.

Method of making a hyperabrupt varactor diode utilizing molecular beam epitaxy

Disclosed are new high frequency ion implanted passivated semiconductor devices and a planar fabrication process therefor wherein initially an ion implantation and PN junction passivation mask is formed on one surface of a semiconductor crystal. Thereafter, one or more conductivity type determining ion species are implanted through an opening in the mask and into the semiconductor crystal to form active device regions including a PN junction, all of which are bounded by an annular, higher resistivity unimplanted region of the semiconductor crystal. The PN junction thus formed terminates beneath the implantation and passivation mask, and the semiconductor crystal is then annealed to remove ion implantation damage and to electrically activate the ion implanted regions, while simultaneously controlling the lateral movement of the PN junction beneath the passivation mask. Such annealing does not adversely affect the conductivity and passivation characteristics of either the higher resistivity annular region or the passivation mask, and the resultant device structure exhibits a small degradation in high frequency performance relative to comparable state of the art unpassivated devices. Devices fabricated with the present new passivated geometry have a structure with sufficient mechanical strength to allow direct mounting into high frequency circuits (of the microwave waveguide-cavity type) without the use of additional package arrangements.

Ion implantation process for fabricating high frequency avalanche devices

In the method of the present invention, a lightly doped layer of semiconductive material is epitaxially grown on a relatively highly doped substrate so as to provide a relatively sharply defined transition in conductivity between the epitaxial layer and the original substrate material. Further, additional dopant material of the same conductivity type is implanted into the layer by particle bombardment thereby to provide a conductivity profile in which conductivity decreases with depth through the layer substantially down to the essentially uniform conductivity of the original epitaxial material. A dopant providing conductivity of the opposite type is diffused into a relatively shallow portion of the epitaxial layer so as to form a diode junction in the layer. In the diode so formed, the depth of the depletion region varies as a predictable function of the controlled conductivity profile in the epitaxial layer. Since the substrate provides a region of high conductivity just beyond the epitaxial layer, the Q of the device is relatively high.

Diode having a voltage variable capacitance characteristic and method of making same

: The final report is made on the fabrication of MOS transistors by ion implantation. Two different n-channel depletion mode MOS transistors were fabricated. These transistors are to be used to compare surface states of the ion implanted units with surface states of conventional diffused devices. (Author)

Carl H Guild

Papers

Diode having a voltage variable capacitance characteristic and method of making same

Ion implanted mos device.