USH134H - Buried junction enhanced Schottky barrier device - Google Patents

Buried junction enhanced Schottky barrier device Download PDF

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Publication number
USH134H
USH134H US06/643,139 US64313984A USH134H US H134 H USH134 H US H134H US 64313984 A US64313984 A US 64313984A US H134 H USH134 H US H134H
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United States
Prior art keywords
metal
substrate
transition metal
diode
type silicon
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Abandoned
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US06/643,139
Inventor
Lyn H. Skolnik
Sven A. Roosild
Freeman D. Shepherd, Jr.
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United States Department of the Air Force
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United States Department of the Air Force
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Priority to US06/643,139 priority Critical patent/USH134H/en
Assigned to UNITED STATES OF AMERICA AS REPRESENTED BY THE SECRETARY OF THE AIR FORCE reassignment UNITED STATES OF AMERICA AS REPRESENTED BY THE SECRETARY OF THE AIR FORCE ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: SHEPHERD, FREEMAN D. JR., SKOLNIK, LYN H., ROOSILD, SVEN A.
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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
    • H10F30/00—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors
    • H10F30/20—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices having potential barriers, e.g. phototransistors
    • H10F30/21—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices having potential barriers, e.g. phototransistors the devices being sensitive to infrared, visible or ultraviolet radiation
    • H10F30/22—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices having potential barriers, e.g. phototransistors the devices being sensitive to infrared, visible or ultraviolet radiation the devices having only one potential barrier, e.g. photodiodes
    • H10F30/227—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices having potential barriers, e.g. phototransistors the devices being sensitive to infrared, visible or ultraviolet radiation the devices having only one potential barrier, e.g. photodiodes the potential barrier being a Schottky barrier
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
    • H10D8/00—Diodes
    • H10D8/60—Schottky-barrier diodes 
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
    • H10F30/00—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors
    • H10F30/20—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices having potential barriers, e.g. phototransistors
    • H10F30/21—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices having potential barriers, e.g. phototransistors the devices being sensitive to infrared, visible or ultraviolet radiation
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
    • H10F71/00—Manufacture or treatment of devices covered by this subclass
    • H10F71/131—Recrystallisation; Crystallization of amorphous or microcrystalline semiconductors
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates generally to infrared detector devices, and in particular to such a detector utilizing a completely submersed Schottky barrier junction.
  • Such an interface is commonly referred to as a Schottky barrier device and acts in a similar fashion to a p-n semiconductor junction.
  • Such Schottky barrier devices are well known and have been extensively reported and utilized.
  • the present invention contemplates a completely submersed Schottky barrier junction in order to enhance collection efficiency of photogenerated carriers.
  • Using a buried active back-to-back thin junction allows collection of carriers generated with momentum vectors in both the forward and reverse directions.
  • the quantum efficiency and sensitivity of the infrared detector is substantially enhanced.
  • thicker Schottky metalliations can be used to enhance spectral absorption of incident infrared lights.
  • FIGS. 1, 2 and 3 illustrate various stages in the formation of the buried Schottky barrier IRCCD device of the present invention.
  • FIG. 1 shows a p-type silicon substrate.
  • the substrate has at this stage been oxidized for n+ contacts, guard rings and an n channel. After the n+ material has been diffused in the substrate the oxides are removed. The channel oxide is then grown. A polysilicon gate (CCD transfer gate) is then defined and polysilicon is deposited for the gate.
  • CCD transfer gate CCD transfer gate
  • a window is now defined for the electrode or transition metal, which is preferrably platinum, but could be other metals such as iridium or palladium for example.
  • the deposited metal which is the order of 50 to 100 Angstroms thick, is then sintered to form the metal silicide diode. Thereafter, the unreacted metal is removed, a ring is now etched around the diode to expose the p-type silicon substrate and n+ diffusions.
  • a p-type polysilicon layer is now deposited over the exposed substrate.
  • the added layer is then laser or thermally annealed so that a single layer epitaxial layer regrows over the diode, forming a back-to-back p-Si/MSi/p-Si diode structure.
  • aluminum can be overcoated over either the front or back surface of the structure, but not both, to further enhance optical absorption via optical reflection.
  • the key feature of this invention is the formation of single crystal silicon on both sides of the Schottky sensing electrode via laser or thermal annealing, and the associated advantages of having an embedded electrode for sensing.

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  • Light Receiving Elements (AREA)
  • Electrodes Of Semiconductors (AREA)

Abstract

A Schottky barrier device having a completely submersed Schottky barrier junction to enhance the collection efficiency of photogenerated carriers. A method is also disclosed for manufacturing the device.

Description

STATEMENT OF GOVERNMENT INTEREST
The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.
BACKGROUND OF THE INVENTION
The present invention relates generally to infrared detector devices, and in particular to such a detector utilizing a completely submersed Schottky barrier junction.
When a metal is brought into intimate contact with a semiconductor surface, the resulting metallic semiconductor surface exhibits current rectifying characteristics. Such an interface is commonly referred to as a Schottky barrier device and acts in a similar fashion to a p-n semiconductor junction. Such Schottky barrier devices are well known and have been extensively reported and utilized.
It is also known to build up an array of Schottky barrier devices for infrared sensing, and combining the array with a charge coupled diode readout system for achieving an infrared camara device vidicon system. Such a Schottky diode array is disclosed in U.S. Pat. No. 3,902,066, issued to Sven A. Roosild et al. on Aug. 26, 1975.
Present Schottky infrared charge coupled diode (IRCCD) arrays have low quantum efficiencies (sensitivities) thus limiting their applications for certain thermal imaging scenarios.
It is therefore an object of the present invention to provide an improved Schottky IRCCD device of improved sensitivity and quantum efficiency.
It is a further object of the present invention to provide a method for manufacturing such a device.
SUMMARY OF THE INVENTION
The present invention contemplates a completely submersed Schottky barrier junction in order to enhance collection efficiency of photogenerated carriers. Using a buried active back-to-back thin junction allows collection of carriers generated with momentum vectors in both the forward and reverse directions. Thus, the quantum efficiency and sensitivity of the infrared detector is substantially enhanced. In addition, thicker Schottky metalliations can be used to enhance spectral absorption of incident infrared lights.
BRIEF DESCRIPTION OF THE DRAWING
The foregoing and other advantages, objects and features of this invention will become apparent from the following description when read in conjunction with the accompanying drawing in which:
FIGS. 1, 2 and 3 illustrate various stages in the formation of the buried Schottky barrier IRCCD device of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows a p-type silicon substrate. The substrate has at this stage been oxidized for n+ contacts, guard rings and an n channel. After the n+ material has been diffused in the substrate the oxides are removed. The channel oxide is then grown. A polysilicon gate (CCD transfer gate) is then defined and polysilicon is deposited for the gate.
Referring now to FIG. 2 of the drawings, a window is now defined for the electrode or transition metal, which is preferrably platinum, but could be other metals such as iridium or palladium for example. The deposited metal, which is the order of 50 to 100 Angstroms thick, is then sintered to form the metal silicide diode. Thereafter, the unreacted metal is removed, a ring is now etched around the diode to expose the p-type silicon substrate and n+ diffusions.
As shown in FIG. 3 of the drawings, a p-type polysilicon layer is now deposited over the exposed substrate. The added layer is then laser or thermally annealed so that a single layer epitaxial layer regrows over the diode, forming a back-to-back p-Si/MSi/p-Si diode structure.
At this point aluminum can be overcoated over either the front or back surface of the structure, but not both, to further enhance optical absorption via optical reflection.
The key feature of this invention, as described above, is the formation of single crystal silicon on both sides of the Schottky sensing electrode via laser or thermal annealing, and the associated advantages of having an embedded electrode for sensing.
Although the invention has been described with reference to a particular embodiment, it will be understood to those skilled in the art that the invention is capable of a variety of alternative embodiments within the spirit and scope of the appended claims. For example, the invention applies to all possible metallic Schottky electrodes and is not restricted to either platinum silicide or iridium silicide electrodes.

Claims (10)

What is claimed is:
1. A method for manufacturing a buried junction enhanced Schottky barrier device comprising the steps of:
(a) oxidizing a p-type silicon substrate for contacts, guard rings and an n channel;
(b) diffusing n+ material in defined areas in the front surface of said substrate;
(c) removing oxides from said substrate;
(d) defining and depositing a polysilicon charge transfer gate and gate electrode;
(e) defining an area for the transition metal of said device;
(f) depositing said transition metal and sintering said metal to form a metal-silicon diode;
(g) removing unreacted portions of said metal;
(h) etching a ring around said diode to expose said p-type substrate and n+ diffusions;
(i) depositing p-type silicon over exposed areas of said substrate and said metal silicon diode; and
(j) annealing said device whereby a single layer epitaxial film regrows over said diode to form a back-to-back p-type silicon/metal/p-type silicon diode structure.
2. A method according to claim 1 wherein said transition metal is platinum.
3. A method according to claim 1 wherein said transition metal is iridium.
4. A method according to claim 1 wherein said transition metal is palladium.
5. A method according to claim 1 wherein said transition metal is nickel.
6. A method according to claim 1 and including the additional step of:
overcoating the front surface of said device with aluminium to enhance its optical absorption characteristics.
7. A method according to claim 1 and including the additional step of:
overcoating the back surface of said device with aluminum to enhance its optical absorption characteristics.
8. A buried junction Schottky barrier device comprising:
a semiconductor substrate;
a metal deposited on said substrate to form a first metal-semiconductor interface;
a semiconductor material disposed over the exposed surface of said metal to form a second metal-semiconductor interface; and
means for deriving signals from said first and second metal-semiconductor interface.
9. Apparatus as defined in claim 8 wherein said metal is platinum and said semiconductor substrate is p-type silicon.
10. Apparatus as defined in claim 8 and further comprising:
a layer of aluminum disposed over a surface of said substrate to enhance optical absorption of said apparatus.
US06/643,139 1984-08-22 1984-08-22 Buried junction enhanced Schottky barrier device Abandoned USH134H (en)

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Application Number Priority Date Filing Date Title
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USH134H true USH134H (en) 1986-09-02

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5013682A (en) * 1986-10-22 1991-05-07 Texas Instruments Incorporated Method for selective epitaxy using a WSI mask
FR2682815A1 (en) * 1991-10-18 1993-04-23 Thomson Composants Militaires Photosensitive detector with enhanced resolution

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4169231A (en) 1977-09-22 1979-09-25 Hughes Aircraft Company Buried channel to surface channel CCD charge transfer structure
US4194133A (en) 1975-09-05 1980-03-18 U.S. Philips Corporation Charge coupled circuit arrangements and devices having controlled punch-through charge introduction
US4199691A (en) 1978-06-16 1980-04-22 Rca Corporation CCD Multiple channel network
US4206371A (en) 1978-10-27 1980-06-03 Rca Corporation CCD with differently doped substrate regions beneath a common electrode
US4206470A (en) 1977-09-01 1980-06-03 Honeywell Inc. Thin film interconnect for multicolor IR/CCD
US4208668A (en) 1977-03-29 1980-06-17 Siemens Aktiengesellschaft Charge coupled device with buried zones in a semiconductor substrate for use especially as a light sensor
US4210922A (en) 1975-11-28 1980-07-01 U.S. Philips Corporation Charge coupled imaging device having selective wavelength sensitivity
US4488038A (en) 1982-04-12 1984-12-11 At&T Bell Laboratories Phototransistor for long wavelength radiation

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4194133A (en) 1975-09-05 1980-03-18 U.S. Philips Corporation Charge coupled circuit arrangements and devices having controlled punch-through charge introduction
US4210922A (en) 1975-11-28 1980-07-01 U.S. Philips Corporation Charge coupled imaging device having selective wavelength sensitivity
US4208668A (en) 1977-03-29 1980-06-17 Siemens Aktiengesellschaft Charge coupled device with buried zones in a semiconductor substrate for use especially as a light sensor
US4206470A (en) 1977-09-01 1980-06-03 Honeywell Inc. Thin film interconnect for multicolor IR/CCD
US4169231A (en) 1977-09-22 1979-09-25 Hughes Aircraft Company Buried channel to surface channel CCD charge transfer structure
US4199691A (en) 1978-06-16 1980-04-22 Rca Corporation CCD Multiple channel network
US4206371A (en) 1978-10-27 1980-06-03 Rca Corporation CCD with differently doped substrate regions beneath a common electrode
US4488038A (en) 1982-04-12 1984-12-11 At&T Bell Laboratories Phototransistor for long wavelength radiation

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5013682A (en) * 1986-10-22 1991-05-07 Texas Instruments Incorporated Method for selective epitaxy using a WSI mask
FR2682815A1 (en) * 1991-10-18 1993-04-23 Thomson Composants Militaires Photosensitive detector with enhanced resolution

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Owner name: UNITED STATES OF AMERICA AS REPRESENTED BY THE SEC

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNORS:SKOLNIK, LYN H.;ROOSILD, SVEN A.;SHEPHERD, FREEMAN D. JR.;REEL/FRAME:004366/0686;SIGNING DATES FROM 19840730 TO 19840813

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