Bi-state varactor phase modulation network and process for constructing same

• US 3,914,708 A
• Filed: 01/14/1974
• Issued: 10/21/1975
• Est. Priority Date: 11/09/1972
• Status: Expired due to Term

• Current Assignee: Harry L. Stover, Hayden M. Leedy
• Original Assignee: Harry L. Stover, Hayden M. Leedy
• Inventors: Stover, Harry L., Leedy, Hayden M.
• Primary Examiner(s): Lawrence, James W.
• Assistant Examiner(s): Nussbaum, Marvin
• Application Number:
  US05/432,923
• Time in Patent Office: 645 Days
• Field of Search: 333/31A,31R,98R 332/16R,29R,3R,3V 307/320
• US Class Current: 332/105
• CPC Class Codes: H01L 21/00 Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
• CPC Class Codes: H01L 29/00 Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor H01L31/00 - H01L33/00, H10K10/00, H10N take precedence; details other than of semiconductor bodies or of electrodes thereof H01L23/00; devices consisting of a plurality of solid state components formed in or on a common substrate H01L27/00
• CPC Class Codes: H03C 7/027 using diodes
• CPC Class Codes: H03K 17/74 by the use, as active elements, of diodes by the use of more than one type of semiconductor device H03K17/567; by the use of tunnel diodes H03K17/58; by the use of negative resistance diodes H03K17/70

Abstract

Disclosed is a bi-state varactor diode phase modulation network and process for fabricating the diode wherein conductivity type determining ions are implanted in an epitaxial layer of a semiconductor body to form a desired impurity profile and a varactor PN junction therein. During this ion implantation in which both N and P type ions are separately and independently accelerated into the semiconductor body, an N type impurity profile is initially established within the active epitaxial region and thereafter, a very shallow P region is formed at the epitaxial layer surface. The N type impurity concentration increases going away from the PN junction over a first region of the epitaxial layer and at a controlled slope up to a point of a maximum impurity concentration. Thereafter, the N type impurity concentration decreases over an adjacent, second region of the epitaxial layer and also at a controlled slope to a point of minimum impurity concentration. When a suitable range of bias voltage is applied to the varactor to reverse bias its PN junction, the concentration of carriers in the above first and second regions of the epitaxial layer is such that the junction capacitance of the varactor may be switched at frequencies at least up to about 100 gigahertz (GHz) and on a relatively steep slope between two substantially constant values of junction capacitance. Alternatively, a Schottky barrier junction may be used instead of a PN junction.

Claims

1. A low distortion high frequency phase modulation network for introducing a phase change into microwave or millimeter wave signals and having a bistate frequency switching capability at least in excess of approximately 100 gigahertz comprising:

a. conductive means including input and output ports for receiving said signals and for propagating reflected signals, b. a terminating impedance or short connected across said input and output ports, c. a bistate varactor diode connected in parallel with said terminating impedance or short and spaced therefrom an adjustable phase difference theta , and d. means for biasing said varactor diode at one or another of its two relatively stable capacitance states, whereby said varactor diode will either approximate a series resonant condition or an antiresonant condition and thereby cause a predetermined phase delay in signals reflected on said conductive means in accordance with the resonant state of said varactor diode, whereby said varactor diode may be rapidly switched between said capacitance states at frequencies up to and including 100 gigahertz or higher.

2. The phase modulator defined in claim 1 wherein said bistate varactor diode includes an equivalent series connection comprising an equivalent inductance L, and an equivalent series resistance Rs, and a voltage dependent equivalent junction capacitance Cj, all connected in parallel with said terminating impedance or short whereby the terminating reactance jX is equal to jZO tan theta , where

3. The phase modulator defined in claim 1 wherein said varactor diode includes:

a. a semiconductor structure including a layer of one conductivity type semiconductive material having a rectifying junction adjacent one edge thereof; and

b. said layer characterized by an impurity profile which varies in impurity concentration at predetermined and controlled levels and depths beneath said rectifying junction and at controlled slopes between said predetermined impurity concentration levels so that when increasing levels of reverse bias are applied to said rectifying junction, the mobility of charge carriers in said layer causes the capacitance thereacross to change from one relatively stable value of capacitance to another.

4. The diode defined in claim 3 wherein the impurity concentration varies in a first region from approximately 1017 atoms per cubic centimeter toward a maximum level of approximately 8 X 1017 atoms per cubic centimeter, and the impurity concentration varies across a second region from said maximum level to a minimum level of impurity concentration between 1015 and 1016 atoms per cubic centimeter.

5. The diode defined in claim 4 wherein said layer includes therein an opposite conductivity type region which forms a PN junction with said first region.

6. The diode defined in claim 4 wherein a Schottky barrier junction is formed at the surface of said first region.

7. The diode defined in claim 5 wherein said second region is implanted with N-type ions selected from the group consisting of arsenic and phosphorous ions to tailor the doping profile therein, and said opposite conductivity type region is formed by implanted P-type boron ions of a concentration on the order of 1021 atoms per cubic centimeter to form a heavily doped P-type region.

8. The diode defined in claim 6 wherein the impurity concentration varies in said first region from approximately 1017 atoms per cubic centimeter toward a maximum level of approximately 8 X 1017 atoms per cubic centimeter, and the impurity concentration varies across said second region from said maximum level to a minimum level of impurity concentration between 1015 and 1016 atoms per cubic centimeter.

9. A low distortion high frequency phase modulation network for introducing a phase change into microwave or millimeter wave signals including:

a. conductive means including a pair of ports for receiving signals and for propagating reflected signals, b. a terminating impedance connected across said ports, c. a bistate varactor diode connected in parallel with said terminating impedance and spaced therefrom an adjustable phase difference theta , said bistate varactor diode having two relatively constant capacitance plateaus in its capacitance voltage characteristic corresponding respectively to separate ranges of bias voltage for which said varactor diode draws no or negligible current, said varactor diode operative for switching between said plateaus at frequencies up to and including 100 GHz, and d. means for biasing said varactor diode at one or another of its two relatively constant capacitance plateaus, whereby said varactor diode will either approximate a series resonant condition or an anti-resonant condition and thereby cause a predEtermined phase delay in signals reflected to said ports in accordance with the resonant state of said varactor diode.