Trench photosensor for a CMOS imager
2 Assignments
0 Petitions
Accused Products
Abstract
A trench photosensor for use in a CMOS imager having an improved charge capacity. The trench photosensor may be either a photogate or photodiode structure. The trench shape of the photosensor provides the photosensitive element with an increased surface area compared to a flat photosensor occupying a comparable area on a substrate. The trench photosensor also exhibits a higher charge capacity, improved dynamic range, and a better signal-to-noise ratio. Also disclosed are processes for forming the trench photosensor.
53 Citations
209 Claims
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1-123. -123. (Cancelled)
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124. A method of sensing photons comprising:
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receiving said photons into a trench, said trench disposed in a doped layer of a first conductivity type formed in a semiconductor substrate;
activating a diode formed in said substrate adjacent said trench by absorbing said photons, said diode including a first doped region of a second conductivity type formed in a sidewall and bottom of said trench;
receiving charges from said first doped region into a second doped region of said second conductivity type formed in said doped layer; and
resetting a charge level of said second doped region by receiving charges from said second doped region into a conductive signal line. - View Dependent Claims (125, 126, 127, 128, 129, 130)
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131. A method of sensing light comprising:
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receiving said light through an aperture in a surface of a semiconductor substrate;
absorbing said light into an internal surface of said semiconductor substrate, said internal surface defining a cavity within said semiconductor substrate;
energizing an electron of said semiconductor substrate with said absorbed light; and
activating a switching device using said energized electron. - View Dependent Claims (132, 133, 134, 135, 136, 137)
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138. A method of sensing photon flux comprising:
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receiving a first plurality of photons at a bottom surface of a trench photo-capacitor and forming a first plurality of photo-electrons;
receiving a second plurality of photons at a side surface of said trench photo-capacitor and forming a second plurality of photo-electrons; and
generating an output signal related to said first and second pluralities of photo-electrons. - View Dependent Claims (139, 140)
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141-144. -144. (Cancelled)
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145. A method of controlling photo-generated charge carriers comprising:
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receiving a flux of photons at a photo-active surface of a photosensor;
photo-generating charge carriers with said flux of photons;
storing said charge carriers in a trench capacitor;
conducting said charge carriers through a transfer gate channel to a floating diffusion node, said floating diffusion node being electrically coupled to a transistor gate;
conducting said charge carriers from said floating diffusion node to said transistor gate; and
conducting said charge carriers from said transistor gate through a reset gate channel to a supply conductor. - View Dependent Claims (146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166)
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167. A method of signaling to a photosensor to control operation of said photosensor, said method comprising:
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during a first time interval receiving a reset signal at a reset gate disposed above a reset gate channel, said reset gate channel being disposed within a substrate, said reset gate conducting a current between a floating diffusion node disposed within said substrate and a source of reset potential, said reset sample and hold circuit adapted to sample a voltage of said floating diffusion node during said second time interval;
during a second time interval receiving a reset value sample and hold signal at a reset sample and hold circuit coupled, said floating diffusion node being coupled to a gate of a source follower transistor and to a trench capacitor;
during a third time interval, receiving a photo-gate sample and hold signal at a photo-gate disposed above the photo-active surface of said photosensor said photo-active surface being disposed within said trench capacitor; and
during a fourth time interval receiving a signal value sample and hold signal at a signal sample and hold circuit, said signal sample and hold circuit being adapted to sample a voltage of said floating diffusion node during said fourth time interval. - View Dependent Claims (168, 169)
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170. A method of converting an optical signal to an electrical signal comprising:
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receiving said optical signal at a surface of a photoreceptor;
absorbing said optical signal through said surface of said photoreceptor;
energizing a plurality of electrons with said optical signal in relation to an intensity of said optical signal;
storing said plurality of energized electrons in a substantially concave distribution within a substrate and thereby adjusting an electrical potential of a corresponding substantially concave region within said substrate, said substrate supporting said photoreceptor; and
adjusting an electrical output signal of an output circuit in relation to a magnitude of said electrical potential. - View Dependent Claims (171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188)
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189. A method of capturing an image comprising:
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receiving said image at an array of pixel devices, said pixel devices including a plurality of apertures disposed in a surface of a substrate and a plurality of cavities disposed within said substrate beneath said plurality of apertures respectively;
charging a plurality of capacitors to a respective plurality of electrical potentials, said capacitors being disposed adjacent said plurality of cavities respectively, said plurality of electrical potentials related light flux of said image at said respective apertures;
receiving charge from said plurality of capacitors at a respective plurality of transistors;
receiving a plurality of electrical signals from said plurality of transistors respectively; and
recording said plurality of electrical signals to capture said image. - View Dependent Claims (190, 191, 192, 193)
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194. A method for operating a digital image acquisition system comprising:
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receiving an optical image at a CMOS image sensor array, said array including a plurality of photosensors and a respective plurality of controllable transistors, said plurality of photosensors including a respective plurality of trench capacitors, each said trench capacitor having a photosensitive region on a wall thereof;
sensing a plurality of charge values stored on said plurality of trench capacitors respectively; and
producing a plurality of output signals related to said plurality of charge values respectively. - View Dependent Claims (195, 196, 197, 198)
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- 199. (canceled).
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200. A method of forming a photo sensor comprising:
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excavating a trench within a semiconductor substrate, said trench having a substantially vertical internal surface region;
performing a first ion implantation into said substantially vertical internal surface region at a first ion implantation angle;
performing a second ion implantation into said substantially vertical internal surface region at a second ion implantation angle.
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Specification