# US 2014/0191290 A1 · Solid-state imaging element > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0191290 A1 - Document ID: US20140191290A1 - Status: Published application - Kind: A1 - Application number: 14/240,186 - Filed: 2012-07-24 - Published: 2014-07-10 - Earliest claimed: 2011-08-24 - Assignees: Sharp Kabushiki Kaisha - Inventors: Daisuke Funao; Takefumi Konishi - Web page: https://patentgrep.com/patent/US20140191290A1 ## CPC - H10F 39/18: Complementary metal-oxide-semiconductor [CMOS] image sensors; Photodiode array image sensors - H10F 39/802: {Geometry or disposition of elements in pixels, e.g. address-lines or gate electrodes} - H10F 39/80377: {characterised by the channel of the transistor, e.g. channel having a doping gradient} - H10F 39/807: {Pixel isolation structures} - H10F 39/813: {Electronic components shared by multiple pixels, e.g. one amplifier shared by two pixels} - H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION ## Abstract Provided is a solid-state imaging element that effectively reduces 1/f noise from a signal output from a source-follower transistor. The solid-state imaging element includes a first conductivity type substrate 10, a photodiode in which carriers are accumulated in a second conductivity type accumulation region, the second conductivity type being different from the first conductivity type, a source-follower transistor 15 which has a gate electrode 151 electrically connected to a floating diffusion region accumulated with the carriers read out from the photodiode and which is provided with a second conductivity type buried channel, and an element separator 21 which is provided around an active region of the photodiode and the source-follower transistor 15. The buried channel of the source-follower transistor 15 is formed away from a sidewall of the element separator 21. ## Claims ### Claim 1 A solid-state imaging element comprising: a first conductivity type substrate; a photodiode which is formed on the substrate, and in which carriers generated by photoelectric conversion are accumulated in a second conductivity type accumulation region, the second conductivity type being different from the first conductivity type; a source-follower transistor which is formed on the substrate, and which has a gate electrode electrically connected to a floating diffusion region accumulated with the carriers read out from the photodiode and which is provided with a second conductivity type buried channel; and an element separator which is formed on the substrate, and which is provided around an active region of at least the photodiode and the source-follower transistor, wherein the buried channel of the source-follower transistor is formed away from a sidewall of the element separator, the buried channel of the source-follower transistor is formed within a channel formation region provided by injecting a second conductivity type impurity into a surface of the first conductivity type substrate, a concentration of a first conductivity type impurity injected into a side region of the element separator is at a level of canceling a second conductivity type region included in the channel formation region, and the first conductivity type impurity is injected into an outermost surface of the channel formation region of the source-follower transistor. ### Claim 2 (canceled) ### Claim 3 (depends on 1) The solid-state imaging element according to claim 1, wherein the concentration of the first conductivity type impurity injected into the side region of the element separator is at least two times the concentration of the second conductivity type impurity injected into the second conductivity type region included in the channel formation region of the source-follower transistor. ### Claim 4 (canceled) ### Claim 5 (depends on 1) The solid-state imaging element according to claim 1, wherein the first conductivity type impurity is also injected into a lower region of the element separator. ### Claim 6 (depends on 3) The solid-state imaging element according to claim 3, further comprising: a transfer transistor which is formed on the substrate, and which has the accumulation region as a source and the floating diffusion region as a drain; and a reset transistor which is formed on the substrate, and which has the floating diffusion region as a source and a predetermined potential as a drain. ### Claim 7 (depends on 6) The solid-state imaging element according to claim 6, wherein the reset transistor is provided with a second conductivity type buried channel. ### Claim 8 (depends on 6) The solid-state imaging element according to claim 6, wherein a separation direction of the source and the drain of the transfer transistor is different from a separation direction of the source and the drain of the source-follower transistor. ### Claim 9 (depends on 1) The solid-state imaging element according to claim 1, further comprising: a selection transistor in which the drain is shared with the source of the source-follower transistor or the source is shared with the drain of the source-follower transistor. ### Claim 10 (depends on 9) The solid-state imaging element according to claim 9, wherein the selection transistor is provided with a second conductivity type buried channel. ### Claim 11 (depends on 1) The solid-state imaging element according to claim 1, wherein the element separator is an STI including at least one of an oxide and a nitride. ### Claim 12 (depends on 1) The solid-state imaging element according to claim 1, wherein a gate electrode of at least one transistor provided with the buried channel is formed such that an end part of the gate electrode recedes from a position immediately above the element separator. ### Claim 13 (depends on 1) The solid-state imaging element according to claim 1, wherein a gate insulating film that is provided immediately below a gate electrode of at least one transistor provided with the buried channel is formed such that a thickness of a portion near the element separator is larger than a thickness of a portion away from the element separator. ### Claim 14 (depends on 5) The solid-state imaging element according to claim 5, further comprising: a transfer transistor which is formed on the substrate, and which has the accumulation region as a source and the floating diffusion region as a drain; and a reset transistor which is formed on the substrate, and which has the floating diffusion region as a source and a predetermined potential as a drain. ### Claim 15 (depends on 14) The solid-state imaging element according to claim 14, wherein the reset transistor is provided with a second conductivity type buried channel. ### Claim 16 (depends on 14) The solid-state imaging element according to claim 14, wherein a separation direction of the source and the drain of the transfer transistor is different from a separation direction of the source and the drain of the source-follower transistor. ### Claim 17 (depends on 1) The solid-state imaging element according to claim 1, further comprising: a transfer transistor which is formed on the substrate, and which has the accumulation region as a source and the floating diffusion region as a drain; and a reset transistor which is formed on the substrate, and which has the floating diffusion region as a source and a predetermined potential as a drain. ### Claim 18 (depends on 17) The solid-state imaging element according to claim 17, wherein the reset transistor is provided with a second conductivity type buried channel. ### Claim 19 (depends on 17) The solid-state imaging element according to claim 17, wherein a separation direction of the source and the drain of the transfer transistor is different from a separation direction of the source and the drain of the source-follower transistor.