SOLID-STATE IMAGING DEVICE, PROCESS OF MAKING SOLID STATE IMAGING DEVICE, DIGITAL STILL CAMERA, DIGITAL VIDEO CAMERA, MOBILE PHONE, AND ENDOSCOPE

• US 20110049591A1
• Filed: 08/27/2010
• Published: 03/03/2011
• Est. Priority Date: 08/28/2009
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: NAKATANI, Toshihiro, SUZUKI, Hideyuki, MAEHARA, Yoshiki, GOTO, Takashi
• Granted Patent: US 8,378,397 B2
• Time in Patent Office: Days
• US Class Current: 257/292
• CPC Class Codes: H01L 27/14647 Multicolour imagers having a stacked pixel-element structure, e.g. npn, npnpn or MQW elements
• CPC Class Codes: H04N 23/10 for generating image signals from different wavelengths
• CPC Class Codes: H04N 25/134 based on three different wavelength filter elements
• CPC Class Codes: H04N 25/531 by controlling rolling shutters in CMOS SSIS
• CPC Class Codes: H04N 25/65 applied to reset noise, e.g. KTC noise related to CMOS structures by techniques other than CDS
• CPC Class Codes: H04N 25/77 Pixel circuitry, e.g. memories, A/D converters, pixel amplifiers, shared circuits or shared components
• CPC Class Codes: H10K 30/353 comprising blocking layers, e.g. exciton blocking layers
• CPC Class Codes: H10K 30/88 Passivation; Containers; Encapsulations
• CPC Class Codes: H10K 39/32 Organic image sensors
• CPC Class Codes: Y02E 10/549 Organic PV cells

Abstract

A solid-state imaging device includes an array of pixels, each pixel includes: a pixel electrode; an organic layer; a counter electrode; a sealing layer; a color filter; a readout circuit; and a light-collecting unit as defined herein, the photoelectric layer contains an organic p type semiconductor and an organic n type semiconductor, the organic layer further includes a charge blocking layer as defined herein, an ionization potential of the charge blocking layer and an electron affinity of the organic n type semiconductor in the photoelectric layer has a difference of at least 1 eV, and the sealing layer includes a first sealing sublayer formed by atomic layer deposition and a second sealing sublayer formed by physical vapor deposition and containing one of a metal oxide, a metal nitride, and a metal oxynitride.

Claims

1. A solid-state imaging device comprising an array of pixels, each pixel comprising:

a pixel electrode;

an organic layer which is provided above the pixel electrode and comprises a photoelectric layer generating charges in response to light received;

a counter electrode which is provided above the organic layer and common to the pixels;

a sealing layer covering the counter electrode;

a color filter provided above the sealing layer;

a readout circuit reading a signal corresponding to the charge collected by the pixel electrode; and

a light-collecting unit for leading light transmitted through the color filter to the photoelectric layer of the pixel where the color filter is located,

the photoelectric layer containing an organic p type semiconductor and an organic n type semiconductor,

the organic layer further comprising a charge blocking layer between the photoelectric layer and at least one of the pixel electrode and the counter electrode and to block charge injection from the at least one of the pixel electrode and the counter electrode to the photoelectric layer,

an ionization potential of the charge blocking layer and an electron affinity of the organic n type semiconductor in the photoelectric layer having a difference of at least 1 eV, and

the sealing layer comprising a first sealing sublayer formed by atomic layer deposition and a second sealing sublayer formed by physical vapor deposition and containing one of a metal oxide, a metal nitride, and a metal oxynitride.

2. The solid-state imaging device according to claim 1, wherein the second sealing sublayer is formed by sputtering and contains one of aluminum oxide, silicon oxide, silicon nitride, and silicon oxynitride.

3. The solid-state imaging device according to claim 1, wherein the first sealing sublayer has a thickness of 0.05 to 0.2 μ

m.

4. The solid-state imaging device according to claim 1, wherein the first sealing sublayer contains one of aluminum oxide, silicon oxide, and titanium oxide.

5. The solid-state imaging device according to claim 1, wherein each pixel further comprises a buffer layer formed by physical vapor deposition between the counter electrode and the sealing layer.

6. The solid-state imaging device according to claim 5, wherein the buffer layer contains one of silicon oxide, silicon nitride, and silicon oxynitride.

7. The solid-state imaging device according to claim 1, wherein the readout circuit comprises:

a floating diffusion node electrically connected to the pixel electrode and changing its potential in response to the potential of the pixel electrode and

an MOS transistor circuit reading out a signal in response to the potential of the floating diffusion node.

8. The solid-state imaging device according to claim 7, wherein the MOS transistor circuit comprises a reset transistor, the voltage supplied to the source terminal of the reset transistor is lower than the voltage supplied to the counter electrode so that an electric current flows from the counter electrode to the pixel electrode to collect holes in the pixel electrode, and each transistor of the MOS transistor circuit is of an n-channel MOS type.

9. The solid-state imaging device according to claim 7, wherein the MOS transistor circuit comprises a reset transistor, the voltage supplied to the source terminal of the reset transistor is higher than the voltage supplied to the counter electrode so that an electric current flows from the pixel electrode to the counter electrode to collect electrons in the pixel electrode, and each transistor of the MOS transistor circuit is of a p-channel MOS type.

10. The solid-state imaging device according to claim 7, wherein the readout circuit further comprises a protection for preventing the potential of the floating diffusion node from exceeding or falling below a prescribed threshold.

11. The solid-state imaging device according to claim 10, wherein the protection is a transistor or a diode, being connected to the floating diffusion node.

12. The solid-state imaging device according to claim 7, wherein the readout circuit further comprises a unit for reducing kTC noise.

13. The solid-state imaging device according to claim 1, wherein the light-collecting unit comprises a transparent partition wall between adjacent color filters of adjacent pixels, the partition wall having a lower refractive index than the color filters.

14. The solid-state imaging device according to claim 13, wherein the partition wall contains a fluororesin.

15. A method of fabricating the solid-state imaging device according to claim 13, comprising, in the following order:

forming red color filters and blue color filters in a Bayer array,

forming the partition walls,

forming green color filters, and

planarizing the red color filters, the blue color filters, the green color filters, and the partition walls by chemical mechanical polishing or etch-back.

16. The method of fabricating the solid-state imaging device according to claim 15, wherein the color filters are formed by dry etching.

17. A digital still camera comprising the solid-state imaging device according to claim 1.

18. A digital video camera comprising the solid-state imaging device according to claim 1.

19. A mobile phone comprising the solid-state imaging device according to claim 1.

20. An endoscope comprising the solid-state imaging device according to claim 1.