CA1062355A - Charge coupled image sensor device - Google Patents
Charge coupled image sensor deviceInfo
- Publication number
- CA1062355A CA1062355A CA250,989A CA250989A CA1062355A CA 1062355 A CA1062355 A CA 1062355A CA 250989 A CA250989 A CA 250989A CA 1062355 A CA1062355 A CA 1062355A
- Authority
- CA
- Canada
- Prior art keywords
- layer
- image sensor
- sensor device
- crystalline
- electrodes
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 32
- 239000001301 oxygen Substances 0.000 claims abstract description 32
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 32
- 229910021420 polycrystalline silicon Inorganic materials 0.000 claims abstract description 19
- 239000000758 substrate Substances 0.000 claims abstract description 15
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical group O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 38
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 19
- 229910052710 silicon Inorganic materials 0.000 claims description 19
- 239000010703 silicon Substances 0.000 claims description 19
- 235000012239 silicon dioxide Nutrition 0.000 claims description 19
- 239000000377 silicon dioxide Substances 0.000 claims description 19
- 239000004065 semiconductor Substances 0.000 claims description 6
- 238000009413 insulation Methods 0.000 claims description 3
- 238000002161 passivation Methods 0.000 abstract description 5
- 230000035945 sensitivity Effects 0.000 abstract description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 4
- 229910052782 aluminium Inorganic materials 0.000 description 4
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- 239000000969 carrier Substances 0.000 description 2
- 238000005229 chemical vapour deposition Methods 0.000 description 2
- 229910052681 coesite Inorganic materials 0.000 description 2
- 229910052906 cristobalite Inorganic materials 0.000 description 2
- 230000003446 memory effect Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 229910052682 stishovite Inorganic materials 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- 229910052905 tridymite Inorganic materials 0.000 description 2
- 206010034960 Photophobia Diseases 0.000 description 1
- 229910021417 amorphous silicon Inorganic materials 0.000 description 1
- 239000012159 carrier gas Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 229910021419 crystalline silicon Inorganic materials 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000005468 ion implantation Methods 0.000 description 1
- 208000013469 light sensitivity Diseases 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
- H01L27/146—Imager structures
- H01L27/148—Charge coupled imagers
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—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
- H01L29/40—Electrodes ; Multistep manufacturing processes therefor
- H01L29/43—Electrodes ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
- H01L29/49—Metal-insulator-semiconductor electrodes, e.g. gates of MOSFET
- H01L29/4916—Metal-insulator-semiconductor electrodes, e.g. gates of MOSFET the conductor material next to the insulator being a silicon layer, e.g. polysilicon doped with boron, phosphorus or nitrogen
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—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
- H01L29/40—Electrodes ; Multistep manufacturing processes therefor
- H01L29/43—Electrodes ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
- H01L29/49—Metal-insulator-semiconductor electrodes, e.g. gates of MOSFET
- H01L29/4966—Metal-insulator-semiconductor electrodes, e.g. gates of MOSFET the conductor material next to the insulator being a composite material, e.g. organic material, TiN, MoSi2
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—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
- H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
- H01L29/68—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by only the electric current supplied, or only the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched
- H01L29/76—Unipolar devices, e.g. field effect transistors
- H01L29/762—Charge transfer devices
- H01L29/765—Charge-coupled devices
- H01L29/768—Charge-coupled devices with field effect produced by an insulated gate
- H01L29/76866—Surface Channel CCD
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Computer Hardware Design (AREA)
- Ceramic Engineering (AREA)
- Electromagnetism (AREA)
- Chemical & Material Sciences (AREA)
- Composite Materials (AREA)
- Materials Engineering (AREA)
- Solid State Image Pick-Up Elements (AREA)
- Transforming Light Signals Into Electric Signals (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A CCD image sensor having impurity-doped polycrystalline silicon electrodes and an oxygen doped polycrystalline silicon layer lying between the electrodes and overlying a photosensitive portion of a substrate so as to provide an improved passivation in that low leakage current between electrodes result and a high sensitivity to shorter wave lengths of light are obtained as compared with devices utilizing pure polycrystalline layers.
A CCD image sensor having impurity-doped polycrystalline silicon electrodes and an oxygen doped polycrystalline silicon layer lying between the electrodes and overlying a photosensitive portion of a substrate so as to provide an improved passivation in that low leakage current between electrodes result and a high sensitivity to shorter wave lengths of light are obtained as compared with devices utilizing pure polycrystalline layers.
Description
CRO.~S-l~EFERENCES T() E'~ET ATED PATENT
Canadian Patent ~u~ber 1,029,475, issue~ April 11, 1978, entitled '~semiconductor Device" in which the inventors are T. Matsushita, H. Hayashi, T. Aoki, H. Yamamoto and Y. Kawana assigned to the same assignee of the present invention discloses a polycrystalline silicon layer as a passivation layer formed on a semiconductor singly crystal layer in a semiconductor device.
BACKGROUND OF THE INVENTION
Field of the Invention: -This invention relates-to a solid state image sensor, especially employing a charge coupled device (CCD). The CCD device .- includes a surface CCD, a bulk CCD or a bucket brigate device (BBD).
BRIEF DESCRIPIION OF THE DRAWINGS
.: , , Figure 1 illustrates a CCD device of the prior art, ..
: ~ Figure 2 is a plan view illustrating.a frametransfer device ` of the prior art, .
Figure 3 illustrates an inter-line transfer system according to the prior art, Figure 4 illustrates a CCD device of the prior art, Figure 5 illustrates a first embodiment of the present . invention, Figure 6 illustrates a modified form of the invention, - Figure 7 is a plot of oxygen content versus resistivity characteristic, Figure 8 illustrates apparatus used to manufacture devices ',J' according to the invention,.
Figure 9 is a graph showing the oxygen concentration versus the band gap energy characteristic, r :
Figure lO is a plan view of a modified form of the invention, Figure 11 is a sectional view taken on line A-A in Figure 10, and Figure 12 is a sectional view of the apparatus shown in Figure 10 taken on sectional line B-B.
Description of the Prior Art:
Figure 1 illustrates a conventional three phase CCD
having an N-type silicon substrate 1 upon which a silicon lO dioxide layer 2 is formed and with transfer electrodes 3 formed on top of the silicon dioxide layer 2. Clock pulses 01' 02 and 03 are applied to the gate electrodes 3.
Two phase surface CCD devices are also known in which the thickness of the silicon dioxide layer 2 under each elec-trode 3 is varied in the charge transferring direction to form a step-like potential well for carriers.
: A frame transfer system or an inter-line transfer system is employed in the solid state image sensors of the prior ~ art.
: 20 A frame transfer system is illustrated in Figure 2 which has an image area 5 and a storage area 6 and includes a shift register 7. Charges generated by incident light in ; the image area 5 are simultaneously transferred to the storage area 6 and are sequentially read out from the shift register 7.
I The inter-line transfer system is illustrated in Y~ Figure 3 and has vertical image areas 8, vertical shift regis-`~ ters 9 and a horizontal shift register lO. Charges generated ;~ by the light in the image areas 8 are simultaneously trans-ferred to the vertical shift registers 9 and are sequentially ~- 30 transferred to the horizontal shift register lO. :
In Figure l charges are generated by light energy which passes through the silicon dioxide layer 2 between the t C ~ 3-r ,- . . , - ~ , ' ' .. , . . ~' -.; . . . . .
electrodes 3. Such devices have good light sensitivity but have an unstable passivation when the silicon dioxide layer 2 is exposed because of contaminating positive charges in the silicon dioxide layer. These positive charges cause a memory effect which is undesirable.
- Figure 4 illustrates another known CCD device in which pure polycrystalline silicon 11 is deposited completely over the silicon dioxide layer 2 and impurities are selectively diffused into the silicon layer 11 to form low resistivity regions lla. Aluminum is deposited on the pure polycrystalline layer 11 to form transfer electrodes 3. Such device has good passivation but the sensitivity of shorter wave length light is lowered because of the existence of the silicon layer 11.
Also, the resistivity of the silicon layer 11 is not high enough to prevent leakage currents from occurring between the , electrodes 3. -~ SUMMARY OF THE INVENTION
:,' ~' The object of the present invention is to provide an improved CCD image sensor in which oxygen doped polycrystalline silicon is between the electrodes.
The present device has good passivation as compared ~, with devices using only a silicon dioxide layer and has low leakage current between the electrodes and a very high sensiti-.~
vity to shorter wave length light (blue) as compared with devices using pure polycrystalline layer.
The polycrystalline silicon in this invention may include amorphous silicon.
In accordance with the foregoing objects, there is .J provided:-an image sensor comprising:
, a semiconductor substrate;
an insulating layer on said substrate;
_ 4 _ transfer electrodes on said insulating layer; and an oxygen doped poly-crystalline silicon layer on said insulating layer.
Other objects, features and advantages of the inven-tion will be readily apparent from the following description of certain preferred embodiments thereof taken in conjunction with the accompanying drawings although variations and modifi-cations may be effected without departing from the spirit and scope of the novel concepts of the disclosure.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Figure 5 illustrates a first embodiment of the present invention in which a silicon dioxide layer 2 is formed on a N-type silicon substrate 1. An oxygen doped polycrystalline silicon layer 13 is formed all over the silicon dioxide layer 2.
Impurities are selectively doped into the oxygen doped poly-`~ crystalline silicon layer 13 by diffusion or ion implantation to form low resistivity regions 13a. Aluminum electrodes 14 are deposited on the regions 13a to form transfer electrodes 3. Photosensitive portions 15 exist between the electrodes 3.
', Figure 6 illustrates a modified form of the invention ~ in which an oxygen doped polycrystalline silicon layer 13 is -~ deposited over the silicon dioxide layer 2 on the substrate 1 ~ and aluminum electrodes 3 are formed over the polycrystalline , .
' silicon layer 13. In either of the embodiments illustrated 1~ in Figures 5 and 6 the photogeneration portion between the ,, electrodes 3 is covered by the silicon dioxide layer and the oxygen doped polycrystalline layer. The oxygen concentration in the polycrystalline silicon layer 13 is maintained in the range 10 to 50 atomic %.
The oxygen concentration in the polycrystalline ` silicon is plotted versus the resistivity in Figure 7. The ,., ~,l, . .:
''~' C ql '}
mean silicon grain size is 200 to 300 A. It is to be noted that the resistivity increases as ~' .~
"
., .~
.~ :
.1 - Sa -, ~. ' , ' ' . ' ' ' ' '' ' the oxygen concentration increas~s.
The polycrystalline layer 13 has a mean grain size in the range betweell 50 to 1000 A. If the grain size is less than 50 A the properties of the polycrystalline silicon will approach that of silicon dioxidc and the memory effect will appear which is undesirable. Also, it requires a low reaction temperature and, thus, the growth rate will be small. If the grain size is more than 1000 A the leakage current increases which is undesirable.
The oxygen doped polycrystalline silicon layer 13 is obtained by chemical vapor deposition (CVD) as shown in Figure 8. A reactor 21 contains the substrate 1 which is heated to the range of 600 to 750 C
for example to a temperature of 650 C. A carrier gas source (N2) 22, a silicon source (SiH4) 23 and an oxygen source (N2O,NO or NO2) 24 supply input to the reactor 21 through the valves 25, 26 and 27. SiH4 is used because it produces the desired polycrystalline silicon at a relatively low reaction temperature. If SiC14 is used it will require a higher reaction temperature such as 900 C which will result in larger grain size and larger leakage currents. The oxygen concentration is controlled by the flow ratio of the N2O and the SiH4.
As the semi-insulating silicon layer 13 covers the SiO2 layer 2 the surface state of the silicon substrate 1 is stabilized because charges in the silicon layer 13 neutralize the charges in the SiO2 layer
Canadian Patent ~u~ber 1,029,475, issue~ April 11, 1978, entitled '~semiconductor Device" in which the inventors are T. Matsushita, H. Hayashi, T. Aoki, H. Yamamoto and Y. Kawana assigned to the same assignee of the present invention discloses a polycrystalline silicon layer as a passivation layer formed on a semiconductor singly crystal layer in a semiconductor device.
BACKGROUND OF THE INVENTION
Field of the Invention: -This invention relates-to a solid state image sensor, especially employing a charge coupled device (CCD). The CCD device .- includes a surface CCD, a bulk CCD or a bucket brigate device (BBD).
BRIEF DESCRIPIION OF THE DRAWINGS
.: , , Figure 1 illustrates a CCD device of the prior art, ..
: ~ Figure 2 is a plan view illustrating.a frametransfer device ` of the prior art, .
Figure 3 illustrates an inter-line transfer system according to the prior art, Figure 4 illustrates a CCD device of the prior art, Figure 5 illustrates a first embodiment of the present . invention, Figure 6 illustrates a modified form of the invention, - Figure 7 is a plot of oxygen content versus resistivity characteristic, Figure 8 illustrates apparatus used to manufacture devices ',J' according to the invention,.
Figure 9 is a graph showing the oxygen concentration versus the band gap energy characteristic, r :
Figure lO is a plan view of a modified form of the invention, Figure 11 is a sectional view taken on line A-A in Figure 10, and Figure 12 is a sectional view of the apparatus shown in Figure 10 taken on sectional line B-B.
Description of the Prior Art:
Figure 1 illustrates a conventional three phase CCD
having an N-type silicon substrate 1 upon which a silicon lO dioxide layer 2 is formed and with transfer electrodes 3 formed on top of the silicon dioxide layer 2. Clock pulses 01' 02 and 03 are applied to the gate electrodes 3.
Two phase surface CCD devices are also known in which the thickness of the silicon dioxide layer 2 under each elec-trode 3 is varied in the charge transferring direction to form a step-like potential well for carriers.
: A frame transfer system or an inter-line transfer system is employed in the solid state image sensors of the prior ~ art.
: 20 A frame transfer system is illustrated in Figure 2 which has an image area 5 and a storage area 6 and includes a shift register 7. Charges generated by incident light in ; the image area 5 are simultaneously transferred to the storage area 6 and are sequentially read out from the shift register 7.
I The inter-line transfer system is illustrated in Y~ Figure 3 and has vertical image areas 8, vertical shift regis-`~ ters 9 and a horizontal shift register lO. Charges generated ;~ by the light in the image areas 8 are simultaneously trans-ferred to the vertical shift registers 9 and are sequentially ~- 30 transferred to the horizontal shift register lO. :
In Figure l charges are generated by light energy which passes through the silicon dioxide layer 2 between the t C ~ 3-r ,- . . , - ~ , ' ' .. , . . ~' -.; . . . . .
electrodes 3. Such devices have good light sensitivity but have an unstable passivation when the silicon dioxide layer 2 is exposed because of contaminating positive charges in the silicon dioxide layer. These positive charges cause a memory effect which is undesirable.
- Figure 4 illustrates another known CCD device in which pure polycrystalline silicon 11 is deposited completely over the silicon dioxide layer 2 and impurities are selectively diffused into the silicon layer 11 to form low resistivity regions lla. Aluminum is deposited on the pure polycrystalline layer 11 to form transfer electrodes 3. Such device has good passivation but the sensitivity of shorter wave length light is lowered because of the existence of the silicon layer 11.
Also, the resistivity of the silicon layer 11 is not high enough to prevent leakage currents from occurring between the , electrodes 3. -~ SUMMARY OF THE INVENTION
:,' ~' The object of the present invention is to provide an improved CCD image sensor in which oxygen doped polycrystalline silicon is between the electrodes.
The present device has good passivation as compared ~, with devices using only a silicon dioxide layer and has low leakage current between the electrodes and a very high sensiti-.~
vity to shorter wave length light (blue) as compared with devices using pure polycrystalline layer.
The polycrystalline silicon in this invention may include amorphous silicon.
In accordance with the foregoing objects, there is .J provided:-an image sensor comprising:
, a semiconductor substrate;
an insulating layer on said substrate;
_ 4 _ transfer electrodes on said insulating layer; and an oxygen doped poly-crystalline silicon layer on said insulating layer.
Other objects, features and advantages of the inven-tion will be readily apparent from the following description of certain preferred embodiments thereof taken in conjunction with the accompanying drawings although variations and modifi-cations may be effected without departing from the spirit and scope of the novel concepts of the disclosure.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Figure 5 illustrates a first embodiment of the present invention in which a silicon dioxide layer 2 is formed on a N-type silicon substrate 1. An oxygen doped polycrystalline silicon layer 13 is formed all over the silicon dioxide layer 2.
Impurities are selectively doped into the oxygen doped poly-`~ crystalline silicon layer 13 by diffusion or ion implantation to form low resistivity regions 13a. Aluminum electrodes 14 are deposited on the regions 13a to form transfer electrodes 3. Photosensitive portions 15 exist between the electrodes 3.
', Figure 6 illustrates a modified form of the invention ~ in which an oxygen doped polycrystalline silicon layer 13 is -~ deposited over the silicon dioxide layer 2 on the substrate 1 ~ and aluminum electrodes 3 are formed over the polycrystalline , .
' silicon layer 13. In either of the embodiments illustrated 1~ in Figures 5 and 6 the photogeneration portion between the ,, electrodes 3 is covered by the silicon dioxide layer and the oxygen doped polycrystalline layer. The oxygen concentration in the polycrystalline silicon layer 13 is maintained in the range 10 to 50 atomic %.
The oxygen concentration in the polycrystalline ` silicon is plotted versus the resistivity in Figure 7. The ,., ~,l, . .:
''~' C ql '}
mean silicon grain size is 200 to 300 A. It is to be noted that the resistivity increases as ~' .~
"
., .~
.~ :
.1 - Sa -, ~. ' , ' ' . ' ' ' ' '' ' the oxygen concentration increas~s.
The polycrystalline layer 13 has a mean grain size in the range betweell 50 to 1000 A. If the grain size is less than 50 A the properties of the polycrystalline silicon will approach that of silicon dioxidc and the memory effect will appear which is undesirable. Also, it requires a low reaction temperature and, thus, the growth rate will be small. If the grain size is more than 1000 A the leakage current increases which is undesirable.
The oxygen doped polycrystalline silicon layer 13 is obtained by chemical vapor deposition (CVD) as shown in Figure 8. A reactor 21 contains the substrate 1 which is heated to the range of 600 to 750 C
for example to a temperature of 650 C. A carrier gas source (N2) 22, a silicon source (SiH4) 23 and an oxygen source (N2O,NO or NO2) 24 supply input to the reactor 21 through the valves 25, 26 and 27. SiH4 is used because it produces the desired polycrystalline silicon at a relatively low reaction temperature. If SiC14 is used it will require a higher reaction temperature such as 900 C which will result in larger grain size and larger leakage currents. The oxygen concentration is controlled by the flow ratio of the N2O and the SiH4.
As the semi-insulating silicon layer 13 covers the SiO2 layer 2 the surface state of the silicon substrate 1 is stabilized because charges in the silicon layer 13 neutralize the charges in the SiO2 layer
2.
As the oxygen doped silicon layer 13 covers the photosensitive portions 15 of the substrate the sensitivity to the shorter wave length light (blue) increases as compared to devices u6ing pure polycrystalline silicon because the band gap energy in the oxygen doped polycrystalline -. ~ . ' . . ' ' ' ' ' - ' ,~
,, , ' : ~ .
silicon is larger than that of the pure polycrystalline silicon.
The oxygen concentration in atomic ~, is plotted in Figure 9 versus the band gap energy distribution. Polycrystalline silicon containing 36 to 49 atomic % oxygen has a wider band gap by 0,2 to 0. 4 electron volts than that of pure silicon.
The existence of the layer 13 improves the insulation between the electrodes 3 and the substrate 1 even when they are pin holes in the silicon dioxide layer 2.
Figures 10, 11 and 12 illustrate a second embodiment of the invention applied to a two phase CCD device employing the inter-line transfer system. FigurelO is a plan view illustrating the substrate 1 upon which are formed a silicon dioxide layer 2 as illustrated in ~igures 11 and 12 which are respectively sectional vie~staken on llne A-A in Figure 10 and line B-B in Figure 10. The illustrated embodiment is applied to a two phase CCD device employing inter-line transfer system using image areas 8 and shift registers 9. Oxygen dopes polycrystalline layer 13 illustrated in Figure 11 and 10 is formed over the silicon dioxide layer 2. Impurity doped polycrystalline layer electrodes 3 on a silicon dioxide layer 2 are formed, and an oxygen doped polycrystalline silicon layer 13 is formed over the silicon layer 3. Photogenerated carriers originate beneath a photosensitive portion 15 and are transferred beneath the electrodes 3 in the A-A direction. There are provided step-like potentials beneath the electrodes 3 to prevent the reverse flow of the charges. Channel stoppers 33 illustrated in Figure 11 are also provided. The charges are sequentially transferred in vertical shift registers 9 in the B-B direction. Aluminum electrode layers 34 may cover the oxygen doped polycrystalline silicon layer 13 except over the ~ . . . . .
: - '' "' ' ~
photosensitive regions 15.
It is seen that this inventioll provides a new and novel CCD
device and altllough it has been described with respect to preferred embodiments it is not to be so limited as changes and modifications may be made which are within the full intended scope as defined by the appended claims.
.. . .
. . . -. .
.~ .
,.
, ......... .
s~
,, .
, .. . 8 , . , ~ .
As the oxygen doped silicon layer 13 covers the photosensitive portions 15 of the substrate the sensitivity to the shorter wave length light (blue) increases as compared to devices u6ing pure polycrystalline silicon because the band gap energy in the oxygen doped polycrystalline -. ~ . ' . . ' ' ' ' ' - ' ,~
,, , ' : ~ .
silicon is larger than that of the pure polycrystalline silicon.
The oxygen concentration in atomic ~, is plotted in Figure 9 versus the band gap energy distribution. Polycrystalline silicon containing 36 to 49 atomic % oxygen has a wider band gap by 0,2 to 0. 4 electron volts than that of pure silicon.
The existence of the layer 13 improves the insulation between the electrodes 3 and the substrate 1 even when they are pin holes in the silicon dioxide layer 2.
Figures 10, 11 and 12 illustrate a second embodiment of the invention applied to a two phase CCD device employing the inter-line transfer system. FigurelO is a plan view illustrating the substrate 1 upon which are formed a silicon dioxide layer 2 as illustrated in ~igures 11 and 12 which are respectively sectional vie~staken on llne A-A in Figure 10 and line B-B in Figure 10. The illustrated embodiment is applied to a two phase CCD device employing inter-line transfer system using image areas 8 and shift registers 9. Oxygen dopes polycrystalline layer 13 illustrated in Figure 11 and 10 is formed over the silicon dioxide layer 2. Impurity doped polycrystalline layer electrodes 3 on a silicon dioxide layer 2 are formed, and an oxygen doped polycrystalline silicon layer 13 is formed over the silicon layer 3. Photogenerated carriers originate beneath a photosensitive portion 15 and are transferred beneath the electrodes 3 in the A-A direction. There are provided step-like potentials beneath the electrodes 3 to prevent the reverse flow of the charges. Channel stoppers 33 illustrated in Figure 11 are also provided. The charges are sequentially transferred in vertical shift registers 9 in the B-B direction. Aluminum electrode layers 34 may cover the oxygen doped polycrystalline silicon layer 13 except over the ~ . . . . .
: - '' "' ' ~
photosensitive regions 15.
It is seen that this inventioll provides a new and novel CCD
device and altllough it has been described with respect to preferred embodiments it is not to be so limited as changes and modifications may be made which are within the full intended scope as defined by the appended claims.
.. . .
. . . -. .
.~ .
,.
, ......... .
s~
,, .
, .. . 8 , . , ~ .
Claims (11)
1. An image sensor comprising:
a semiconductor substrate;
an insulating layer on said substrate;
transfer electrodes on said insulating layer; and an oxygen doped poly-crystalline silicon layer on said insulating layer.
a semiconductor substrate;
an insulating layer on said substrate;
transfer electrodes on said insulating layer; and an oxygen doped poly-crystalline silicon layer on said insulating layer.
2. An image sensor according to claim 1, in which said silicon layer lies between said electrodes and overlies a photo-sensitive portion.
3. An image sensor device comprising:
a semiconductor substrate of a first conductivity type, an insulating layer on a major surface of said substrate, an oxygen doped poly-crystalline layer on said insulating layer and a plurality of electrodes formed on spaced regions of said oxygen doped poly-crystalline layer.
a semiconductor substrate of a first conductivity type, an insulating layer on a major surface of said substrate, an oxygen doped poly-crystalline layer on said insulating layer and a plurality of electrodes formed on spaced regions of said oxygen doped poly-crystalline layer.
4. An image sensor device according to claim 3 wherein the oxygen concentration in said oxygen doped poly-crystalline region is in the range of 10 to 50 atomic per cent.
5. An image sensor device according to claim 4 wherein the mean grain size of said poly-crystalline layer is in the range of 50 to 1000 Angstroms.
6. An image sensor device according to claim 3 wherein said spaced regions of oxygen doped poly-crystalline region layer under said plurality of electrodes have lower resistivity than the remaining portions of said oxygen doped poly-crystalline layer.
7. An image sensor device according to claim 6 wherein the oxygen concentration in said oxygen doped poly-crystalline , region is in the range of 10 to 50 atomic per cent.
8. An image sensor device according to claim 7 wherein the mean grain size of said poly-crystalline layer is in the range of 50 to 1,000 Angstroms.
9. A image sensor device according to claim 1 wherein said insulation layer is silicon dioxide.
10. A image sensor device according to claim 4 wherein said insulation layer is silicon dioxide.
11. A image sensor device according to claim 4 wherein the oxygen content of said poly-crystalline layer is in the range of 36 to 49 atomic per cent.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP50052735A JPS51128285A (en) | 1975-04-30 | 1975-04-30 | Solid photographing unit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1062355A true CA1062355A (en) | 1979-09-11 |
Family
ID=12923174
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA250,989A Expired CA1062355A (en) | 1975-04-30 | 1976-04-26 | Charge coupled image sensor device |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS51128285A (en) |
| CA (1) | CA1062355A (en) |
| DE (1) | DE2618964C2 (en) |
| FR (1) | FR2309982A1 (en) |
| GB (1) | GB1518459A (en) |
| NL (1) | NL7604557A (en) |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3826926A (en) * | 1972-11-29 | 1974-07-30 | Westinghouse Electric Corp | Charge coupled device area imaging array |
| JPS5824951B2 (en) * | 1974-10-09 | 1983-05-24 | ソニー株式会社 | Kougakusouchi |
-
1975
- 1975-04-30 JP JP50052735A patent/JPS51128285A/en active Pending
-
1976
- 1976-04-26 GB GB1688176A patent/GB1518459A/en not_active Expired
- 1976-04-26 CA CA250,989A patent/CA1062355A/en not_active Expired
- 1976-04-28 NL NL7604557A patent/NL7604557A/en not_active Application Discontinuation
- 1976-04-29 DE DE19762618964 patent/DE2618964C2/en not_active Expired
- 1976-04-30 FR FR7613049A patent/FR2309982A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS51128285A (en) | 1976-11-09 |
| DE2618964A1 (en) | 1976-11-11 |
| FR2309982B1 (en) | 1979-08-31 |
| NL7604557A (en) | 1976-11-02 |
| DE2618964C2 (en) | 1984-06-14 |
| GB1518459A (en) | 1978-07-19 |
| FR2309982A1 (en) | 1976-11-26 |
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