Browse Prior Art Database

Infrared Photo Detectors Produced by Cluster Beam Deposition Of Aluminum Films On Silicon

IP.com Disclosure Number: IPCOM000121006D
Original Publication Date: 1991-Jul-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 3 page(s) / 138K

Publishing Venue

IBM

Related People

Lu, TM: AUTHOR [+3]

Abstract

A technique is described whereby large-scale integration (LSI), high- sensitivity and high-resolution infrared photo detectors are produced by means of cluster beam deposition of aluminum films on silicon.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 51% of the total text.

Infrared Photo Detectors Produced by Cluster Beam Deposition Of Aluminum
Films On Silicon

      A technique is described whereby large-scale integration
(LSI), high- sensitivity and high-resolution infrared photo detectors
are produced by means of cluster beam deposition of aluminum films on
silicon.

      Typically, diodes of metal/p-Si can be used as high-efficient
photo detectors to detect light with a wavelength of approximately 1
mm, provided that their Schottky barrier height is from 0.2 to 0.4 eV
and the metal contact is thin, Z 100 o, and uniform over the entire
contact area.  The advantage of using Si rather than Cd Hg Te as the
active substrate is the ability of integrating a large number of
diodes on a chip.  The result is better sensitivity and resolution of
the image.  In addition, there is better control of the Si
crystalline quality as well as a large set of silicides which offer a
wide range of selection of Schottky barrier height.

      Near-noble metal silicides have been studied for infrared
detector applications, such as the Schottky barrier height of IrSi,
PtSi, RhSi and Pd2Si on p-type Si [1].  The result was 0.17, 0.23,
0.3 and 0.36 eV, respectively.  A typical diode structure, as shown
in the figure, consists of a thin silicide contact to p-Si covered
with an anti-reflective coating connected to the outside circuitry by
an interconnecting wire [2].

      By using silicide contacts in the detector, two major
difficulties have been encountered.  The first problem is how to
overcome the native oxide on the surface of the Si, which tends to
retard silicide formation, resulting in a non-uniform reaction and
non-uniform silicide/Si interface.  To resolve this problem, it is
possible to deposit an ultra-thin layer of a chemically reactive
metal, such as Ti or Er, onto the Si surface before the deposition of
Pt or Pd.  The purpose of depositing the Ti or Er is to dissolve away
the oxide for silicide reaction.  However, it is known that during
near-noble metal silicide formation, metal atoms are the diffusing
species.  The Ti-O or Er-O product will be transported to the surface
where it is found to have caused adhesion problems to the
subsequently deposited anti- reflective coating.  The second problem
is how to produce a thin and uniform silicide film with a homogeneous
interface to Si.  Grain boundaries in the polycrystalline silicide
film reduce quantum efficiency and sensitivity and resolution of
images.  Although single-crystal silicide films are ideal,
difficulties existed in fabricating a single-crystal film of PtSi or
Pd2Si on (100) Si.  Only preferred oriented films have been made [3].

      The concept described herein utilizes cluster ion beam
deposition methods to produce thin and uniform Al films on (100) Si
for applications in infrared detection.  By using cluster ion beam
deposition, a single crystal Al film can be deposited of uniform
thickness (Z 100o) on (100) Si.  The ...