CA1106477A - Overflow channel for charge transfer imaging devices - Google Patents
Overflow channel for charge transfer imaging devicesInfo
- Publication number
- CA1106477A CA1106477A CA161,619A CA161619A CA1106477A CA 1106477 A CA1106477 A CA 1106477A CA 161619 A CA161619 A CA 161619A CA 1106477 A CA1106477 A CA 1106477A
- Authority
- CA
- Canada
- Prior art keywords
- medium
- integration sites
- area
- region
- forming
- 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
- 238000012546 transfer Methods 0.000 title claims abstract description 52
- 238000003384 imaging method Methods 0.000 title claims abstract description 34
- 230000010354 integration Effects 0.000 claims abstract description 89
- 239000002800 charge carrier Substances 0.000 claims description 34
- 239000012535 impurity Substances 0.000 claims description 26
- 239000004065 semiconductor Substances 0.000 claims description 21
- 239000002184 metal Substances 0.000 claims description 20
- 239000012212 insulator Substances 0.000 claims description 19
- 238000003860 storage Methods 0.000 claims description 18
- 238000001514 detection method Methods 0.000 claims description 7
- 239000000969 carrier Substances 0.000 claims description 6
- 239000000758 substrate Substances 0.000 claims 6
- 230000004888 barrier function Effects 0.000 claims 3
- 230000005284 excitation Effects 0.000 claims 3
- 238000005036 potential barrier Methods 0.000 claims 1
- 238000009825 accumulation Methods 0.000 abstract 1
- 239000004020 conductor Substances 0.000 description 7
- 238000009792 diffusion process Methods 0.000 description 6
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 241001663154 Electron Species 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000000370 acceptor Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 230000005574 cross-species transmission Effects 0.000 description 1
- AMHIJMKZPBMCKI-PKLGAXGESA-N ctds Chemical compound O[C@@H]1[C@@H](OS(O)(=O)=O)[C@@H]2O[C@H](COS(O)(=O)=O)[C@H]1O[C@H]([C@@H]([C@H]1OS(O)(=O)=O)OS(O)(=O)=O)O[C@H](CO)[C@H]1O[C@@H](O[C@@H]1CO)[C@H](OS(O)(=O)=O)[C@@H](OS(O)(=O)=O)[C@@H]1O[C@@H](O[C@@H]1CO)[C@H](OS(O)(=O)=O)[C@@H](OS(O)(=O)=O)[C@@H]1O[C@@H](O[C@@H]1CO)[C@H](OS(O)(=O)=O)[C@@H](OS(O)(=O)=O)[C@@H]1O[C@@H](O[C@@H]1CO)[C@H](OS(O)(=O)=O)[C@@H](OS(O)(=O)=O)[C@@H]1O[C@@H](O[C@@H]1CO)[C@H](OS(O)(=O)=O)[C@@H](OS(O)(=O)=O)[C@@H]1O2 AMHIJMKZPBMCKI-PKLGAXGESA-N 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000010894 electron beam technology Methods 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 239000007943 implant Substances 0.000 description 1
- 238000005468 ion implantation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 229910052682 stishovite Inorganic materials 0.000 description 1
- 229910052905 tridymite Inorganic materials 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
- H01L27/14887—Blooming suppression
-
- 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
- H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
- H01L29/06—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions
- H01L29/10—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions with semiconductor regions connected to an electrode not carrying current to be rectified, amplified or switched and such electrode being part of a semiconductor device which comprises three or more electrodes
- H01L29/1025—Channel region of field-effect devices
- H01L29/1062—Channel region of field-effect devices of charge coupled devices
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Computer Hardware Design (AREA)
- Electromagnetism (AREA)
- Ceramic Engineering (AREA)
- Solid State Image Pick-Up Elements (AREA)
- Transforming Light Signals Into Electric Signals (AREA)
Abstract
OVERFLOW CHANNEL FOR CHARGE
TRANSFER IMAGING DEVICES
Abstract of the Disclosure A structure is described for preventing the blooming effect in charge transfer imaging devices caused by excessive charge accumulation. A drain region is provided adjacent to integration sites in order to collect the excess charge. Means are included for maintaining the proper surface potential between the drain and integrating electrodes so that excess charge will flow into the drain and not into areas under adjacent integrating or transfer electrodes.
TRANSFER IMAGING DEVICES
Abstract of the Disclosure A structure is described for preventing the blooming effect in charge transfer imaging devices caused by excessive charge accumulation. A drain region is provided adjacent to integration sites in order to collect the excess charge. Means are included for maintaining the proper surface potential between the drain and integrating electrodes so that excess charge will flow into the drain and not into areas under adjacent integrating or transfer electrodes.
Description
11~)64~7'7 Background of the Invention This invention relates to charge transfer imaging devices and in particular to a scheme designed to avoid blooming in such devices.
"Charge Transfer Device" (CTD) has come to be known as the generic description for devices which store and trans-fer charge carriers in a semiconductor medium by means of appropriate potentials applied to an array of electrodes disposed upon an insulating layer covering one surface of the medium. These devices may be of the charge coupled (CCD) or bucket brigade (sBD) type. In the sucket Brigade Device, diffused regions are provided in the semiconductor beneath each electrode and extend slightly into the area below an adjacent electrode in the charge transfer path. When an electrode is pulsed, the diffusion immediately under it is reverse biased and the channel between this diffusion and its neighbor is inverted. Thus, charge isstored in the diffusions as majority carriers and transferred through the channel regions between diffusions as minority carriers. The ssD
may be thought of as a series of IGFET devices. The CCD on the other hand stores charge in the potential wells created under depletion biased electrodes and transfers charge by creating a succession of potential wells along the semi-conductor surface. Thus, charge is stored and transferred as minority carriers and the need for "source" and "drain"
diffused regions is eliminated.
It was known that minority charge carriers can be generated in a semiconductor by the creation of hole elec-tron pairs through photon absorption. The charge transfer - 30 device has therefore been suggested for imaging applications wherein charge is generated and stored in the medium in proportion to light incident on the device and 1~6477 read out by merely biasing the electrodes in the proper sequence. Such a device would eliminate the need for electron beam readout and therefore allow the fabrication of more compact and inexpensive video tubes.
One significant problem associated with the use of CTDs for imaging applications is that of "blooming". This occurs when incident light is of sufficient intensity such that excessive charge carriers are generated in some integration sites (whether the diffused regions of the BBD
or depleted regions of the CCD). This excess charge will then "spill over" into adjacent sites causing undesired white areas over a substantial portion of the final display.
It is therefore the primary object of the present invention to prevent significant blooming in a charge transfer imaging device.
Summary of the Invention This and other objects are achieved in accordance with the invention wherein a drain is provided to collect excess charge carriers, which drain in a preferred embodiment is in the form of reverse biased strips of impurity regions in the semiconductor medium adjacent to all the integration sites. Means are further provided for maintaining the proper surface potential between the drain and the integration sites so that excess charge will flow into the drain rather than into areas under adjacent electrodes. This scheme may be provided for both area imaging and line imaging devices.
In accordance with an aspect of the invention there is provided in a charge transfer imaging device comprising a charge storage medium, an insulating layer covering at ~6477 least a portion of one surface of said medium, means for forming localized integration sites in said medium for the collection of mobile charge carriers generated in said medium in response to light incident on said medium, and an array of metal electrodes disposed on said layer defining at least one charge transfer path in said medium wherein said mobile charge carriers may be transferred in a direction essentially parallel to said surface out of said integration sites for detection when a suitable bias is supplied to said electrodes, wherein the improvement comprises means for forming in a region in said medium outside of said charge transfer path and adjacent to each of said integration sites a first surface potential which is attractive to said mobile charge carriers and means for forming a second surface potential in said medium in the area between each integration site and an adjoining region such that excess mobile carriers in said integration sites will transfer to said region.
Brief Description of the Drawinq These and other features of the invention will be delineated in detail in the description to follow. In the drawing:
FIG. 1 is a plan view, partially cut away, of a ~liO69~77 charge coupled area imaging device in accordance with one embodiment of the present invention;
FIG. 2 is a cross-sectional ~iew, partly schematic, along line 2-2 of FIG. i;
FIG. 3 is a cross-sectional view, partly schematic, of a charge coupled imaging device in accordance with another embodiment of the invention;
FIG. ~ is a cross-sectional view, partly schematic, of a charge coupled imaging device in accordance with a further embodiment of the present invention;
FIG. 5 is a plan vlew, partially cut away, of a charge coupled line imaging device in accordance with another embodiment of the invention; and FIGS. 6A and 6B are cross-sectional views, partially schematic, along line 6A, 6B-6A, 6B of FIG. 5.
Detailed Description of the Invention The structure of the present invention is illustrated in the p]an view of FIG. 1 which shows a charge coupled imaging device of the frame transfer and store type. Tha-t is, the device comprises an imaging area wherein the charge is collected in response to incident light and a storage and readout area shielded from light to w~ich the charge is transferred for readout in order to avoid smearing. Clearly, the invention may be applied to other CCD structures. In addition, it will be immediately apparent to those skilled in the art that the invention may be used in similar Bucket Brigade Devices.
The imaging device basically comprises a semi-conductor storage medium 10, such as silicon, an insulating layer 11, such as SiO2 overlying the medium and an array of electrodes disposed thereon to provide charge storage and transfer in the medium. In the structure shown, ., C. H. Sequin 7 1 these electrodes are actually metal fingers o~ conductors labelled ~ 2i' ~ls' ~2s' ~lr and ~2r- In all but the 3 last row of the device, each finger constitutes one row of 4 electrodes in the array. The fingers are effectively separated into individual electrodes in a row by vertical 6 strips of an impurity region 12, which form discrete colu~ns 7 of transfer regions 13 in the semiconductor mediumO This 8 impurity region will be described in more detail below.
9 In the last row o~ the array, each metal finger is an individual electrode. The third and fifth electrodes in 11 this row are coupled to ~lr by a diffused crossunder 12 (not shown). This row is designed to transfer charge to 13 the right to some output means which is usually a diffused 14 region in the semiconductor (not shown) which is reverse biased by a conductor 14 to col]ect the charge. The output 16 means may take any of a number of forms well known in the 17 art.
18 Thus, the device shown comprises a 3 x 12 array 19 of CCD electrodes and a readout row of six CCD electrodes, The first six rows comprise the imaging area and the last 21 seven rows which are shielded from light comprise the storage 22 and readout area. (The first three rows of the imaging area 23 have been cut away in FIG. 1.) During an integration period, 24 either ~li or ~2i is held at a constant potential Vp, in order to collect charge carrier packets in the transfer 26 regions under the metal fingers coupled thereto. The 27 alternate rows are held at a low rest potential Vr. The 28 entire frame is then transferred to the storage area by an 29 appropriate pulsing of conductors ~ 2i~ ~ls and ~2s 30 between Vr and Vp. Each row of charge is then transferred `
31 successively to the readout row by pulsing ~ls' ~2s and ~lr~
32 and read ou-t laterally by pulsing ~lr and ~2r The means ~i~64~
C. Ho Se~uin 7 1 for biasing these electrodes are well known in the art and
"Charge Transfer Device" (CTD) has come to be known as the generic description for devices which store and trans-fer charge carriers in a semiconductor medium by means of appropriate potentials applied to an array of electrodes disposed upon an insulating layer covering one surface of the medium. These devices may be of the charge coupled (CCD) or bucket brigade (sBD) type. In the sucket Brigade Device, diffused regions are provided in the semiconductor beneath each electrode and extend slightly into the area below an adjacent electrode in the charge transfer path. When an electrode is pulsed, the diffusion immediately under it is reverse biased and the channel between this diffusion and its neighbor is inverted. Thus, charge isstored in the diffusions as majority carriers and transferred through the channel regions between diffusions as minority carriers. The ssD
may be thought of as a series of IGFET devices. The CCD on the other hand stores charge in the potential wells created under depletion biased electrodes and transfers charge by creating a succession of potential wells along the semi-conductor surface. Thus, charge is stored and transferred as minority carriers and the need for "source" and "drain"
diffused regions is eliminated.
It was known that minority charge carriers can be generated in a semiconductor by the creation of hole elec-tron pairs through photon absorption. The charge transfer - 30 device has therefore been suggested for imaging applications wherein charge is generated and stored in the medium in proportion to light incident on the device and 1~6477 read out by merely biasing the electrodes in the proper sequence. Such a device would eliminate the need for electron beam readout and therefore allow the fabrication of more compact and inexpensive video tubes.
One significant problem associated with the use of CTDs for imaging applications is that of "blooming". This occurs when incident light is of sufficient intensity such that excessive charge carriers are generated in some integration sites (whether the diffused regions of the BBD
or depleted regions of the CCD). This excess charge will then "spill over" into adjacent sites causing undesired white areas over a substantial portion of the final display.
It is therefore the primary object of the present invention to prevent significant blooming in a charge transfer imaging device.
Summary of the Invention This and other objects are achieved in accordance with the invention wherein a drain is provided to collect excess charge carriers, which drain in a preferred embodiment is in the form of reverse biased strips of impurity regions in the semiconductor medium adjacent to all the integration sites. Means are further provided for maintaining the proper surface potential between the drain and the integration sites so that excess charge will flow into the drain rather than into areas under adjacent electrodes. This scheme may be provided for both area imaging and line imaging devices.
In accordance with an aspect of the invention there is provided in a charge transfer imaging device comprising a charge storage medium, an insulating layer covering at ~6477 least a portion of one surface of said medium, means for forming localized integration sites in said medium for the collection of mobile charge carriers generated in said medium in response to light incident on said medium, and an array of metal electrodes disposed on said layer defining at least one charge transfer path in said medium wherein said mobile charge carriers may be transferred in a direction essentially parallel to said surface out of said integration sites for detection when a suitable bias is supplied to said electrodes, wherein the improvement comprises means for forming in a region in said medium outside of said charge transfer path and adjacent to each of said integration sites a first surface potential which is attractive to said mobile charge carriers and means for forming a second surface potential in said medium in the area between each integration site and an adjoining region such that excess mobile carriers in said integration sites will transfer to said region.
Brief Description of the Drawinq These and other features of the invention will be delineated in detail in the description to follow. In the drawing:
FIG. 1 is a plan view, partially cut away, of a ~liO69~77 charge coupled area imaging device in accordance with one embodiment of the present invention;
FIG. 2 is a cross-sectional ~iew, partly schematic, along line 2-2 of FIG. i;
FIG. 3 is a cross-sectional view, partly schematic, of a charge coupled imaging device in accordance with another embodiment of the invention;
FIG. ~ is a cross-sectional view, partly schematic, of a charge coupled imaging device in accordance with a further embodiment of the present invention;
FIG. 5 is a plan vlew, partially cut away, of a charge coupled line imaging device in accordance with another embodiment of the invention; and FIGS. 6A and 6B are cross-sectional views, partially schematic, along line 6A, 6B-6A, 6B of FIG. 5.
Detailed Description of the Invention The structure of the present invention is illustrated in the p]an view of FIG. 1 which shows a charge coupled imaging device of the frame transfer and store type. Tha-t is, the device comprises an imaging area wherein the charge is collected in response to incident light and a storage and readout area shielded from light to w~ich the charge is transferred for readout in order to avoid smearing. Clearly, the invention may be applied to other CCD structures. In addition, it will be immediately apparent to those skilled in the art that the invention may be used in similar Bucket Brigade Devices.
The imaging device basically comprises a semi-conductor storage medium 10, such as silicon, an insulating layer 11, such as SiO2 overlying the medium and an array of electrodes disposed thereon to provide charge storage and transfer in the medium. In the structure shown, ., C. H. Sequin 7 1 these electrodes are actually metal fingers o~ conductors labelled ~ 2i' ~ls' ~2s' ~lr and ~2r- In all but the 3 last row of the device, each finger constitutes one row of 4 electrodes in the array. The fingers are effectively separated into individual electrodes in a row by vertical 6 strips of an impurity region 12, which form discrete colu~ns 7 of transfer regions 13 in the semiconductor mediumO This 8 impurity region will be described in more detail below.
9 In the last row o~ the array, each metal finger is an individual electrode. The third and fifth electrodes in 11 this row are coupled to ~lr by a diffused crossunder 12 (not shown). This row is designed to transfer charge to 13 the right to some output means which is usually a diffused 14 region in the semiconductor (not shown) which is reverse biased by a conductor 14 to col]ect the charge. The output 16 means may take any of a number of forms well known in the 17 art.
18 Thus, the device shown comprises a 3 x 12 array 19 of CCD electrodes and a readout row of six CCD electrodes, The first six rows comprise the imaging area and the last 21 seven rows which are shielded from light comprise the storage 22 and readout area. (The first three rows of the imaging area 23 have been cut away in FIG. 1.) During an integration period, 24 either ~li or ~2i is held at a constant potential Vp, in order to collect charge carrier packets in the transfer 26 regions under the metal fingers coupled thereto. The 27 alternate rows are held at a low rest potential Vr. The 28 entire frame is then transferred to the storage area by an 29 appropriate pulsing of conductors ~ 2i~ ~ls and ~2s 30 between Vr and Vp. Each row of charge is then transferred `
31 successively to the readout row by pulsing ~ls' ~2s and ~lr~
32 and read ou-t laterally by pulsing ~lr and ~2r The means ~i~64~
C. Ho Se~uin 7 1 for biasing these electrodes are well known in the art and
2 conse~uently are not shown.
3 The novel features of this device can best be seen
4 in the cutaway portions of FIG. 1 and in FIG. 2 which is a cross-sectional view along line 2-2 of FIG. 1. For purposes 6 of illustr~tion, the semiconductor is a p~type material, 7 although the principles described here are equally 8 applicable to an n-type medium by an appropriate reversa] of 9 the polarities shown. As shown in FIG. 1, a first region of impurities 15, of n-~ conductivity type is formed in the 11 semiconductor medium. The region extends through the entire 12 length of the imaging area in vertical strips so as to lie 13 in close proximity to every integration site in the medium.
14 This region is reverse biased by some means, illustrated schematically as a battery 16, so that the region is 16 attractive to the charge carriers, which in this example are 17 electrons. In the areas between the integration sites and 18 the region 15 lies a second region of impurities 12 of 19 p~ conductivity type previously mentioned. Since one of the functions of this region is to define the charge transfer 21 paths, the p+ region extends the full length of the device.
22 ~ince it is only the portion that lies in the imaging area 23 which is operative in terms of the features of the 2~ invention, the full pattern of the p~ region is not shown.
The function of these areas of impurities is 26 illustrated in the cross-sectional view of FIG. 2. The 27 dashed line 17 is a curve illustrating the potential created 28 at the semiconductor surface along one row of the device.
29 In this Figure, ~2i has been biased at a constant potential ~p in the in-tegration mode. Light is incident only on the 11~64~7 second integration site of this row and therefore electrons accumulate there while the first and third sites remain empty. As the second site collects charge, the potential at the surface decreases. As long as the potential at the site ~S remains greater than the threshold potential `YT
created by the impurity region 12 forming the boundary of the transfer region, the charge will be confined to the integration site. However, if the light is sufficiently intense, enough charge will be collected so that ~S is less than or equal to ~T and the charge "overflows" into the adjoining areas. Rather than the charge spilling into adjoining integration sites, however, the lmpurlty region 15 creates a potential ~D which wlll attract the excess charge.
Thus, no distortion of the picture results. The excess charge ls also prevented from overflowing into adjacent rows of integration sites (i.e., ln a directlon perpendicular to the plane of FIG. 2), since ~T is set at a higher value than the potential created by the electrodes coupled to ~li which are held at rest potential during the integration mode. Of course, during the transfer mode, when ~li is pulsed at Vp, the charge in the integration site will be permitted to ~` transfer to an adjacent row. In general, it can be seen that the first region of impurities 15 provides a drain for excess charge carriers, while the second region of impurities 12 remains the proper threshcld potential ~T at the semiconductor surface so that excess charge will transfer to the drain and not to any adjoining integration sites during integration.
Either region of impurities may be formed by 30 standard diffusion or ion implantation techniques. Advan-:~: : .
~ ~ tageouslyj one may diffuse in the impurities of the first :
region during the same step as the formation of the output .
~064~
diode diffusion and then ion implant the second region of impurities in an area which overlaps the first region. Since the first region ls much more heavily doped than the second, the first region will maintain the proper polarity. The impurities of the first region may be any of the many donor impurities known in the art, such as P or As, while the second region may comprise any of the known acceptors such as s. The doping concentration of the first region is preferably approximately 1019 cm 3, although a wide range is permissible as long as the concentration is greater than that of the second region. The doping concentration of the second region should be at least ten times that of the semiconductor medium to insure proper depletion of the surface in these areas according to the principles described above. In a typical device, where Vp = 20 volts and Vr = 2 volts, this concentration is on the order of 1016 cm 3. A determination of the doping concentrations required in accordance with the invention for any particular design is well within the capa-bilities of those skilled in the art. Consequently, a detailed description of this matter is omitted for the sake of brevity.
Many other means are available for maintaining the desired surface potential between the drain and integration sites. Two alternative embodiments are shown in FIGS. 3 and 4, which are again cross-sectional views of one row of an area imaging device which is in the inteyrating mode. In FIG. 3, the metal finger is deposited over an insulator 11 with a stepped geometry which can be formed by standard photolithographic etching techniques well known in the art.
The potential profile 17 is essentially identical to that shown in FIG. 2. The thickness of the stepped insulator is ; - 7 -)6~
C. H. Sequin 7 1 chosen so as to form the surface potential ~T in accordance 2 with the principles described above. For example, where 3 Vp = 20 volts and Vr = 2 volts, the thick portion of the 4 insulator is approximately five times that of the thin portion.
6 In FIG. 4, special threshold electrode 18 is 7 utilized to maintain the proper surface potential '~T- This 8 is a pattern of conducting material overlying the insulator 9 in the form of strips running vertically down the device in basically the same configuration as the impurity region 12 11 of FIG. 1. The strips are coupled at one end of the device 12 to a constant bias means (not shown) which is positive in 13 this example and which magnitude is chosen to ~orrn the 14 desired potential ~T at the boundaries of the integration sites for overflow into the drain. In the device, a second 16 insulator 19 is deposited over the threshold electrode to 17 insulate it from the CCD electrodes (~2i) 18 The principles of the present invention may be 19 extended to the line imaging device as shown in the plan view of FIG. 5. This device is basically the same transfer 21 and store device wherein a row of charge is integrated under 22 conductor ~1 (imaging area) and the row of charge then 23 transferred through the area under ~2 and into the area 24 under the last row comprising conductors ~lr and ~2r~ the latter three conductors overlying an area shielded from 26 incident light comprising the readout area. Again, charge 27 packets are read out by transferring laterally to some 28 output means such as 14. Diffused regions of p+ type 29 conductivity 24 (for a p-type semiconductor medium) are also provided to define the transfer channels as in the area imaging device.
The overflow protection scheme in this embodiment comprises a single rail of impurities 20 of n+ conductivity type (for a p-type medium) which is again reverse-biased by some means 21 to collect mobile charge carriers, and a single metal electrode 22 overlying the insulator in the area between the imaging area and the region of impurities. This electrode is held at a constant positive potential VT by some bias means 23. As shown in FIG. 6A, this constant bias is again chosen so that the potential at the semiconductor surface thereunder ~T is greater than the potential under adjacent electrode ~2 when held at rest potential during the integration mode so that the excess carriers will flow into region 20 and not into the readout,area of the device. As shown in FIG. 6~, when ~2 is pulsed to transfer the row of charge to the readout area, a potential greater than ~T will be established so that none of the charge is transferred to the overflow drain during readout.
Several other practical alternatives are also available for the line imaging device. For example, electrode 22 may be replaced by a horizontal strip of impurities of p~ conductivity type in the medium to provide the necessary surface potential ~T as in the area imaging device. In addition, it is possible to provide as the drain a reverse-biased metal electrode overlying the insulator together with a small region of n~ impurities in the medium at one end of the electrode. The metal electrode would create a depletion region in the medium thereunder to collect the charge while the diode at the end would allow the charge to be drawn out of the medium. Of course, the g _ . . .
6~7 integration sites may be diffused or implanted regions of impurities instead of the biased electrode structure (~
Various additional modifications and extensions will become apparent to those skilled in the art. All such deviations which basically rely on the teachings through which the invention has advanced the art are properly considered within the spirit and scope of the invention.
14 This region is reverse biased by some means, illustrated schematically as a battery 16, so that the region is 16 attractive to the charge carriers, which in this example are 17 electrons. In the areas between the integration sites and 18 the region 15 lies a second region of impurities 12 of 19 p~ conductivity type previously mentioned. Since one of the functions of this region is to define the charge transfer 21 paths, the p+ region extends the full length of the device.
22 ~ince it is only the portion that lies in the imaging area 23 which is operative in terms of the features of the 2~ invention, the full pattern of the p~ region is not shown.
The function of these areas of impurities is 26 illustrated in the cross-sectional view of FIG. 2. The 27 dashed line 17 is a curve illustrating the potential created 28 at the semiconductor surface along one row of the device.
29 In this Figure, ~2i has been biased at a constant potential ~p in the in-tegration mode. Light is incident only on the 11~64~7 second integration site of this row and therefore electrons accumulate there while the first and third sites remain empty. As the second site collects charge, the potential at the surface decreases. As long as the potential at the site ~S remains greater than the threshold potential `YT
created by the impurity region 12 forming the boundary of the transfer region, the charge will be confined to the integration site. However, if the light is sufficiently intense, enough charge will be collected so that ~S is less than or equal to ~T and the charge "overflows" into the adjoining areas. Rather than the charge spilling into adjoining integration sites, however, the lmpurlty region 15 creates a potential ~D which wlll attract the excess charge.
Thus, no distortion of the picture results. The excess charge ls also prevented from overflowing into adjacent rows of integration sites (i.e., ln a directlon perpendicular to the plane of FIG. 2), since ~T is set at a higher value than the potential created by the electrodes coupled to ~li which are held at rest potential during the integration mode. Of course, during the transfer mode, when ~li is pulsed at Vp, the charge in the integration site will be permitted to ~` transfer to an adjacent row. In general, it can be seen that the first region of impurities 15 provides a drain for excess charge carriers, while the second region of impurities 12 remains the proper threshcld potential ~T at the semiconductor surface so that excess charge will transfer to the drain and not to any adjoining integration sites during integration.
Either region of impurities may be formed by 30 standard diffusion or ion implantation techniques. Advan-:~: : .
~ ~ tageouslyj one may diffuse in the impurities of the first :
region during the same step as the formation of the output .
~064~
diode diffusion and then ion implant the second region of impurities in an area which overlaps the first region. Since the first region ls much more heavily doped than the second, the first region will maintain the proper polarity. The impurities of the first region may be any of the many donor impurities known in the art, such as P or As, while the second region may comprise any of the known acceptors such as s. The doping concentration of the first region is preferably approximately 1019 cm 3, although a wide range is permissible as long as the concentration is greater than that of the second region. The doping concentration of the second region should be at least ten times that of the semiconductor medium to insure proper depletion of the surface in these areas according to the principles described above. In a typical device, where Vp = 20 volts and Vr = 2 volts, this concentration is on the order of 1016 cm 3. A determination of the doping concentrations required in accordance with the invention for any particular design is well within the capa-bilities of those skilled in the art. Consequently, a detailed description of this matter is omitted for the sake of brevity.
Many other means are available for maintaining the desired surface potential between the drain and integration sites. Two alternative embodiments are shown in FIGS. 3 and 4, which are again cross-sectional views of one row of an area imaging device which is in the inteyrating mode. In FIG. 3, the metal finger is deposited over an insulator 11 with a stepped geometry which can be formed by standard photolithographic etching techniques well known in the art.
The potential profile 17 is essentially identical to that shown in FIG. 2. The thickness of the stepped insulator is ; - 7 -)6~
C. H. Sequin 7 1 chosen so as to form the surface potential ~T in accordance 2 with the principles described above. For example, where 3 Vp = 20 volts and Vr = 2 volts, the thick portion of the 4 insulator is approximately five times that of the thin portion.
6 In FIG. 4, special threshold electrode 18 is 7 utilized to maintain the proper surface potential '~T- This 8 is a pattern of conducting material overlying the insulator 9 in the form of strips running vertically down the device in basically the same configuration as the impurity region 12 11 of FIG. 1. The strips are coupled at one end of the device 12 to a constant bias means (not shown) which is positive in 13 this example and which magnitude is chosen to ~orrn the 14 desired potential ~T at the boundaries of the integration sites for overflow into the drain. In the device, a second 16 insulator 19 is deposited over the threshold electrode to 17 insulate it from the CCD electrodes (~2i) 18 The principles of the present invention may be 19 extended to the line imaging device as shown in the plan view of FIG. 5. This device is basically the same transfer 21 and store device wherein a row of charge is integrated under 22 conductor ~1 (imaging area) and the row of charge then 23 transferred through the area under ~2 and into the area 24 under the last row comprising conductors ~lr and ~2r~ the latter three conductors overlying an area shielded from 26 incident light comprising the readout area. Again, charge 27 packets are read out by transferring laterally to some 28 output means such as 14. Diffused regions of p+ type 29 conductivity 24 (for a p-type semiconductor medium) are also provided to define the transfer channels as in the area imaging device.
The overflow protection scheme in this embodiment comprises a single rail of impurities 20 of n+ conductivity type (for a p-type medium) which is again reverse-biased by some means 21 to collect mobile charge carriers, and a single metal electrode 22 overlying the insulator in the area between the imaging area and the region of impurities. This electrode is held at a constant positive potential VT by some bias means 23. As shown in FIG. 6A, this constant bias is again chosen so that the potential at the semiconductor surface thereunder ~T is greater than the potential under adjacent electrode ~2 when held at rest potential during the integration mode so that the excess carriers will flow into region 20 and not into the readout,area of the device. As shown in FIG. 6~, when ~2 is pulsed to transfer the row of charge to the readout area, a potential greater than ~T will be established so that none of the charge is transferred to the overflow drain during readout.
Several other practical alternatives are also available for the line imaging device. For example, electrode 22 may be replaced by a horizontal strip of impurities of p~ conductivity type in the medium to provide the necessary surface potential ~T as in the area imaging device. In addition, it is possible to provide as the drain a reverse-biased metal electrode overlying the insulator together with a small region of n~ impurities in the medium at one end of the electrode. The metal electrode would create a depletion region in the medium thereunder to collect the charge while the diode at the end would allow the charge to be drawn out of the medium. Of course, the g _ . . .
6~7 integration sites may be diffused or implanted regions of impurities instead of the biased electrode structure (~
Various additional modifications and extensions will become apparent to those skilled in the art. All such deviations which basically rely on the teachings through which the invention has advanced the art are properly considered within the spirit and scope of the invention.
Claims (22)
1. In a charge transfer imaging device comprising a charge storage medium, an insulating layer covering at least a portion of one surface of said medium, means for forming localized integration sites in said medium for the collection of mobile charge carriers generated in said medium in response to light incident on said medium, and an array of metal electrodes disposed on said layer defining at least one charge transfer path in said medium wherein said mobile charge carriers may be transferred in a direction essentially parallel to said surface out of said integration sites for detection when a suitable bias is supplied to said electrodes, wherein the improvement comprises means for forming in a region in said medium outside of said charge transfer path and adjacent to each of said integration sites a first surface potential which is attractive to said mobile charge carriers, and means for forming a second surface potential in said medium in the area between each integration site and an adjoining region such that excess mobile carriers in said integration sites will transfer to said region.
2. The device according to claim 1 wherein the storage medium is a semiconductor of a first conductivity type and the means for forming said first surface potential comprises a surface region of impurities in said medium of opposite conductivity type to said medium lying adjacent to each of said integration sites.
3. The device according to claim 1 wherein the means for forming the second surface potential in the area between the integration sites and the region comprises an area of insulator overlying the area between the integration sites and the region which is thicker than the area of insulator overlying said integration sites.
4. The device according to claim 1 wherein the means for forming the second surface potential in the area between the integration sites and the region comprises a metal electrode overlying the area between the integration sites and the region.
5. In a charge transfer area imaging device comprising a charge storage medium, an insulating layer covering at least a portion of one surface of said medium, means for forming a two dimensional array of localized integration sites in said medium for the collection of mobile charge carriers generated in said medium in response to light incident on said medium, and an array of metal electrodes disposed on said layer defining a plurality of charge transfer paths in said medium wherein said mobile charge carriers may be transferred in a direction essentially parallel to said surface out of said integration sites for detection when a suitable bias is supplied to said electrodes, wherein the improvement comprises means for forming in a region in said medium outside of said charge transfer paths and adjacent to each of said integration sites a first surface potential which is attractive to said mobile charge carriers, and means for forming a second surface potential in said medium in the area between each integration site and an adjoining region such that excess mobile charge carriers in said integration sites will transfer to said region.
6. The device according to claim 5 wherein the storage medium is a semiconductor of a first conductivity type and the means for forming said first surface potential comprises a surface region of impurities in said medium of opposite conductivity type to said medium, said surface region comprising strips lying adjacent to each column of said two dimensional array of integration sites.
7. The device according to claim 5 wherein the means for forming the second surface potential between said integration sites and said region comprises an area of insul-ator overlying the area between columns of said integration sites which is thicker than the area of insulator overlying the integration sites.
8. The device according to claim 5 wherein the means for forming the second surface potential between said integration sites and said region comprises strips of metal overlying the area between columns of integration sites.
9. In a charge transfer line imaging device comprising a charge storage medium, an insulating layer covering at least a portion of one surface of said medium, means for forming a row of localized integration sites in said medium for the collection of mobile charge carriers generated in said medium in response to light incident on said medium, and an array of metal electrodes disposed on said layer defining a charge transfer path in said medium wherein said mobile charge carriers may be transferred in a direction essentially parallel to said surface out of said integration sites for detection when a suitable bias is supplied to said electrodes, wherein the improvement comprises means for forming in a region in said medium outside of said charge transfer path and adjacent to each of said integration sites a first surface potential which is attractive to said mobile charge carriers, and means for forming a second surface potential in said medium in the area between each integration site and an adjoining region such that excess mobile charge carriers in said integration sites will transfer to said region.
10. The device according to claim 9, wherein the storage medium is a semiconductor of a first conductivity type and the means for forming said first surface potential comprises a surface region of impurities in said medium of opposite conductivity type to said medium, said surface region comprising a strip lying adjacent to said row of integration sites.
11. The device according to claim 9 wherein the means for forming the second surface potential in the area between the integration sites and the region comprises an area of insulator overlying the area between the row of integration sites and the region which is thicker than the area of insulator overlying the integration sites.
12. The device according to claim 9 wherein the means for forming the second surface potential in the area between the integration sites and the region comprises a metal strip overlying the area between said row of integra-tion sites and said region.
13. In a charge transfer imaging device comprising a semiconductor charge storage medium of a first conductivity type, an insulating layer covering at least a portion of one surface of said medium, means for forming localized integra-tion sites in said medium for the collection of mobile charge carriers generated in said medium in response to light incident on said medium, and an array of metal electrodes disposed on said layer defining at least one charge transfer path in said medium wherein said mobile charge carriers may be transferred in a direction essentially parallel to said surface out of said integration sites for detection when a suitable bias is supplied to said electrodes, wherein the improvement comprises a first surface region of impurities of opposite conductivity type to said medium in a region of said medium outside of said charge transfer path and adjacent to each of said integration sites, said first surface region forming a first surface potential which is attractive to said mobile charge carriers when a suitable bias is supplied thereto, and means for forming a second surface potential in the medium in the area between said integration sites and said first surface region such that excess mobile charge carriers in said integration sites will transfer to said first surface region.
14. The device according to claim 13 wherein the means for forming a second surface potential in the medium in the area between the integration sites and the first surface region comprises an area of insulator overlying the area between the integration sites and the first surface region which is thicker than the area of insulator overlying said integration sites.
15. The device according to claim 13 wherein the means for forming a second surface potential in the medium in the area between the integration sites and the first surface region comprises a metal electrode overlying the area between the integration sites and the first surface region.
16. In a charge transfer area imaging device comprising a semiconductor charge storage medium of a first conductivity type, an insulating layer covering at least a portion of one surface of said medium, means for forming a two dimensional array of localized integration sites in said medium for the collection of mobile charge carriers generated in said medium in response to light incident on said medium, and an array of metal electrodes disposed on said layer defining a plurality of charge transfer paths in said medium wherein said mobile charge carriers may be transferred in a direction essentially parallel to said surface out of said integration sites for detection when a suitable bias is supplied to said electrodes, wherein the improvement comprises a first surface region of impurities of opposite conductivity type to said medium in a region of said medium outside of said charge transfer paths and adjacent to each of said integration sites compris-ing strips lying adjacent to each column of said two dimensional array of integration sites, said first surface region forming a first surface potential which is attractive to said mobile charge carriers when a suitable bias is supplied thereto, and means for forming a second surface potential in the medium in the area between said integration sites and said first surface region such that excess mobile charge carriers in said integration sites will transfer to said first surface region.
17. The device according to claim 16 wherein the means for forming a second surface potential in the medium in the area between the integration sites and the first surface region comprises an area of insulator overlying the area between columns of said integration sites which is thicker than the area of insulator overlying the integration sites.
18. The device according to claim 16 wherein the means for forming a second surface potential in the medium in the area between the integration sites and the first surface region comprises strips of metal overlying the area between columns of integration sites.
19. In a charge transfer line imaging device comprising a semiconductor charge storage medium of a first conductivity type, an insulating layer covering at least a portion of one surface of said medium, means for forming a row of localized integration sites in said medium for the collection of mobile charge carriers generated in said medium in response to light incident upon said medium, and an array of metal electrodes disposed on said layer defining a charge transfer path in said medium wherein said mobile charge carriers may be transferred in a direction essentially parallel to said surface out of said integration sites for detection when a suitable bias is supplied to said electrodes, wherein the improvement comprises a first surface region of impurities of opposite conductivity type to said medium in a region of said medium outside of said charge transfer path and adjacent to each of said integration sites comprising a strip lying adjacent to said row of integration sites, said first surface region forming a first surface potential which is attractive to said mobile charge carriers when a suitable bias is supplied thereto, and means for forming second surface potential in the medium in the area between said integration sites and said first surface region such that excess mobile charge carriers in said integra-tion sites will transfer to said first surface region.
20. The device according to claim 19 wherein the means for forming a second surface potential in the medium in the area between the integration sites and the first surface region comprises an area of insulator overlying the area between the row of integration sites and the first surface region which is thicker than the area of insulator overlying the integration sites.
21. The device according to claim 19 wherein the means for forming a second surface potential in the medium in the area between the integration sites and the first surface region comprises a metal strip overlying the area between said row of integration sites and said first surface region.
22. In a charge-coupled radiant energy sensor comprising a substrate, and a row of charge-coupled device charge storage locations, each location for storing charges at the substrate in response to radiant energy excitation, each such location including electrode means insulated from the substrate and at a potential to create a potential well for the storage of charge and electrode means at a potential to create a barrier to the flow of charge from said potential well, the improvement comprising: a bus embedded in the substrate extending in the row direction and located alongside of said row, said bus at a potential to act as a drain for charge signal; and means including an electrode over at least the region of the substrate between the row and the bus and extending along the length of the bus, and means for applying a potential to said electrode for creating a potential barrier at the substrate between said row and said bus at a level lower than that of the barriers at said storage locations but still sufficiently high to permit substantial charge to accumulate at a location in response to radiant energy excitation, whereby when more than this amount of charge signal is produced at a location due to radiant energy excitation, it flows to said bus in prefer-ence to flowing over said barrier at said location.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US27033872A | 1972-07-10 | 1972-07-10 | |
| US270,338 | 1988-11-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1106477A true CA1106477A (en) | 1981-08-04 |
Family
ID=23030921
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA161,619A Expired CA1106477A (en) | 1972-07-10 | 1973-01-19 | Overflow channel for charge transfer imaging devices |
Country Status (9)
| Country | Link |
|---|---|
| JP (1) | JPS5222495B2 (en) |
| BE (1) | BE802002A (en) |
| CA (1) | CA1106477A (en) |
| DE (1) | DE2334116C3 (en) |
| FR (1) | FR2197287B1 (en) |
| GB (1) | GB1413092A (en) |
| IT (1) | IT991964B (en) |
| NL (1) | NL165607C (en) |
| SE (1) | SE382148B (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS49131525A (en) * | 1973-04-05 | 1974-12-17 | ||
| US3866067A (en) * | 1973-05-21 | 1975-02-11 | Fairchild Camera Instr Co | Charge coupled device with exposure and antiblooming control |
| JPS5140790A (en) * | 1974-10-04 | 1976-04-05 | Oki Electric Ind Co Ltd | |
| JPS5732547B2 (en) * | 1974-12-25 | 1982-07-12 | ||
| DE2813254C2 (en) * | 1978-03-28 | 1979-12-06 | Siemens Ag, 1000 Berlin Und 8000 Muenchen | One-dimensional CCD sensor with overflow device |
| JPS5847378A (en) * | 1981-09-17 | 1983-03-19 | Canon Inc | Image pickup element |
| JPS60244064A (en) * | 1984-05-18 | 1985-12-03 | Nec Corp | Solid-state image pickup device |
| JPS60163876U (en) * | 1985-03-06 | 1985-10-31 | 富士通株式会社 | semiconductor imaging device |
| GB2181012B (en) * | 1985-09-20 | 1989-09-13 | Philips Electronic Associated | Imaging devices comprising photovoltaic detector elements |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1566558A (en) * | 1968-03-20 | 1969-05-09 | ||
| IE34899B1 (en) * | 1970-02-16 | 1975-09-17 | Western Electric Co | Improvements in or relating to semiconductor devices |
| FR2101023B1 (en) * | 1970-08-07 | 1973-11-23 | Thomson Csf |
-
1973
- 1973-01-19 CA CA161,619A patent/CA1106477A/en not_active Expired
- 1973-07-02 SE SE7309285A patent/SE382148B/en unknown
- 1973-07-04 NL NL7309340A patent/NL165607C/en not_active IP Right Cessation
- 1973-07-04 GB GB3178373A patent/GB1413092A/en not_active Expired
- 1973-07-05 FR FR7324749A patent/FR2197287B1/fr not_active Expired
- 1973-07-05 DE DE19732334116 patent/DE2334116C3/en not_active Expired
- 1973-07-05 IT IT5127473A patent/IT991964B/en active
- 1973-07-06 BE BE133191A patent/BE802002A/en not_active IP Right Cessation
- 1973-07-10 JP JP48077186A patent/JPS5222495B2/ja not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| SE382148B (en) | 1976-01-12 |
| NL165607C (en) | 1981-04-15 |
| DE2334116A1 (en) | 1974-01-31 |
| NL165607B (en) | 1980-11-17 |
| IT991964B (en) | 1975-08-30 |
| FR2197287A1 (en) | 1974-03-22 |
| FR2197287B1 (en) | 1976-05-28 |
| JPS4946625A (en) | 1974-05-04 |
| JPS5222495B2 (en) | 1977-06-17 |
| BE802002A (en) | 1973-11-05 |
| DE2334116C3 (en) | 1983-11-10 |
| NL7309340A (en) | 1974-01-14 |
| GB1413092A (en) | 1975-11-05 |
| DE2334116B2 (en) | 1977-06-30 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US3896485A (en) | Charge-coupled device with overflow protection | |
| US3866067A (en) | Charge coupled device with exposure and antiblooming control | |
| US4168444A (en) | Imaging devices | |
| US4593303A (en) | Self-aligned antiblooming structure for charge-coupled devices | |
| US3863065A (en) | Dynamic control of blooming in charge coupled, image-sensing arrays | |
| US3896474A (en) | Charge coupled area imaging device with column anti-blooming control | |
| US4155094A (en) | Solid-state imaging device | |
| US4485315A (en) | Blooming suppression in a CCD imaging device | |
| US4527182A (en) | Semiconductor photoelectric converter making excessive charges flow vertically | |
| JP3200436B2 (en) | CCD imager and driving method thereof | |
| US4873561A (en) | High dynamic range charge-coupled device | |
| US3771149A (en) | Charge coupled optical scanner | |
| US3864722A (en) | Radiation sensing arrays | |
| US5130774A (en) | Antiblooming structure for solid-state image sensor | |
| EP0544260A1 (en) | Antiblooming structure for CCD image sensor | |
| US5118631A (en) | Self-aligned antiblooming structure for charge-coupled devices and method of fabrication thereof | |
| US4686555A (en) | Solid state image sensor | |
| US4975777A (en) | Charge-coupled imager with dual gate anti-blooming structure | |
| CA1106477A (en) | Overflow channel for charge transfer imaging devices | |
| JPH0454987B2 (en) | ||
| US4974043A (en) | Solid-state image sensor | |
| EP0059547B1 (en) | Clock controlled anti-blooming for virtual phase ccd's | |
| EP0275180A2 (en) | Solid state imager device | |
| US5442208A (en) | Charge-coupled device having charge reset | |
| EP0069649B1 (en) | Self-aligned antiblooming structure for charge-coupled devices and method of fabrication thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |