SOLID-STATE IMAGING DEVICE AND METHOD FOR MANUFACTURING SAME

• US 20100025791A1
• Filed: 07/29/2009
• Published: 02/04/2010
• Est. Priority Date: 08/01/2008
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Ogawa, Masaaki, Sugiyama, Hitoshi
• Granted Patent: US 7,767,485 B2
• Time in Patent Office: Days
• US Class Current: 257/432
• CPC Class Codes: H01L 2224/05009 Bonding area integrally formed with a via connection of the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/05099 Material
• CPC Class Codes: H01L 2224/05548 Bonding area integrally formed with a redistribution layer on the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/0557 the external layer being disposed on a via connection of the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/13 of an individual bump connector
• CPC Class Codes: H01L 24/05 of an individual bonding area
• CPC Class Codes: H01L 27/14618 Containers
• CPC Class Codes: H01L 27/14621 Colour filter arrangements
• CPC Class Codes: H01L 27/14623 Optical shielding
• CPC Class Codes: H01L 27/14625 Optical elements or arrangements associated with the device
• CPC Class Codes: H01L 27/1464 Back illuminated imager structures
• CPC Class Codes: H01L 27/14683 Processes or apparatus peculiar to the manufacture or treatment of these devices or parts thereof not peculiar thereto H01L21/00
• CPC Class Codes: H01L 27/14685 Process for coatings or optical elements
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details

Abstract

An interconnect layer is formed on a lower face of a silicon wafer, a support substrate is adhered over a lower face of the interconnect layer, and a thickness reduction of the silicon wafer is performed from an upper face side. Next, a photodiode is formed in an upper face of the silicon wafer, and a microlens is formed at a position corresponding to the photodiode. An adhesive layer is formed on the silicon wafer in a region not covering the microlens, a low refractive index layer having a lower refractive index than the microlens is formed in a region covering the microlens, and a glass substrate is adhered to the silicon wafer by the adhesive layer. The support substrate is removed from the interconnect layer, and a solder ball is bonded to a lower face of the interconnect layer. Thereafter, a CMOS image sensor is manufactured by dicing the silicon wafer.

Claims

1. A solid-state imaging device, comprising:

a semiconductor substrate including a photodiode formed in an upper face;

a microlens provided on the semiconductor substrate at a position corresponding to the photodiode;

an adhesive layer provided on the semiconductor substrate not to cover the microlens;

a low refractive index layer provided on the semiconductor substrate to cover the microlens, the low refractive index layer formed from a low-refractive-index material having a refractive index lower than a refractive index of a material forming the microlens;

a transparent substrate covering the adhesive layer and the low refractive index layer, the transparent substrate adhered to the semiconductor substrate by the adhesive layer;

an interconnect layer provided on a lower face of the semiconductor substrate; and

an external connection member bonded to a lower face of the interconnect layer.

2. The device according to claim 1, wherein the transparent substrate contacts both an upper face of the adhesive layer and an upper face of the low refractive index layer.

3. The device according to claim 1, wherein the adhesive layer has a frame-like configuration and the low refractive index layer has a rectangular parallelepiped configuration surrounded by the adhesive layer.

4. The device according to claim 3, wherein

a sensor unit and a peripheral circuit unit are set in the semiconductor substrate, the sensor unit receiving light and converting the light into an electrical signal, the peripheral circuit unit driving the sensor unit and processing the electrical signal output by the sensor unit, and

the adhesive layer is disposed in an outer circumferential side portion of a region directly above the peripheral circuit unit, and the low refractive index layer is disposed in a region directly above the sensor unit and in a region directly above an inner circumferential side portion of the peripheral circuit unit.

5. The device according to claim 1, wherein the low refractive index layer contacts the microlens.

6. The device according to claim 1, wherein the refractive index of the low-refractive-index material is not greater than 1.4.

7. The device according to claim 6, wherein the refractive index of the low-refractive-index material is not greater than 1.3.

8. The device according to claim 1, wherein the refractive index of the material forming the microlens is not less than 1.5.

9. The device according to claim 1, wherein the refractive index of the material forming the microlens is not less than 1.5, and the refractive index of the low-refractive-index material is not greater than 1.4.

10. The device according to claim 1, wherein the transparent substrate is a glass substrate.

11. The device according to claim 1, wherein the external connection member is a solder ball.

12. The device according to claim 1, wherein the device is a CMOS image sensor.

13. A method for manufacturing a solid-state imaging device, comprising:

forming an interconnect layer on a lower face of a semiconductor substrate;

adhering a support substrate over a lower face of the interconnect layer;

performing a thickness reduction of the semiconductor substrate from an upper face side;

forming a photodiode in an upper face of the semiconductor substrate;

forming a microlens on the semiconductor substrate at a position corresponding to the photodiode;

forming an adhesive layer on the semiconductor substrate in a region not covering the microlens and forming a low refractive index layer on the semiconductor substrate in a region covering the microlens, the low refractive index layer made of a low-refractive-index material having a refractive index lower than a refractive index of a material forming the microlens;

adhering a transparent substrate to the semiconductor substrate by the adhesive layer to cover the adhesive layer and the low refractive index layer;

removing the support substrate; and

bonding an external connection member to a lower face of the interconnect layer.

14. The method according to claim 13, wherein a thickness of the semiconductor substrate prior to the thickness reduction is not less than 100 microns, and a thickness of the semiconductor substrate after the thickness reduction is not greater than 10 microns.

15. The method according to claim 13, further comprising

forming an impurity diffusion region in the lower face of the semiconductor substrate,

the forming the impurity diffusion region and the forming the interconnect layer forming:

a drive circuit and a signal processing circuit in a region where a peripheral circuit unit is to be formed, and a transfer transistor and an amplifier transistor in a region where a sensor unit is to be formed.

16. The method according to claim 13, wherein an upper face of the low refractive index layer is formed at substantially the same height as an upper face of the adhesive layer in the forming the adhesive layer and the low refractive index layer.

17. The method according to claim 13, wherein the forming the adhesive layer and the low refractive index layer includes:

forming the adhesive layer on the semiconductor substrate, and

forming the low refractive index layer in a space partitioned by the adhesive layer.

18. A method for manufacturing a solid-state imaging device, comprising:

forming an interconnect layer on a lower face of a semiconductor wafer;

adhering a support substrate over a lower face of the interconnect layer;

performing a thickness reduction of the semiconductor wafer from an upper face side;

forming a photodiode in an upper face of the semiconductor wafer;

forming a microlens on the semiconductor wafer at a position corresponding to the photodiode;

forming an adhesive layer on the semiconductor wafer in a region not covering the microlens and forming a low refractive index layer on the semiconductor wafer in a region covering the microlens, the low refractive index layer made of a low-refractive-index material having a refractive index lower than a refractive index of a material forming the microlens;

adhering a transparent substrate to the semiconductor wafer by the adhesive layer to cover the adhesive layer and the low refractive index layer;

removing the support substrate;

bonding an external connection member to a lower face of the interconnect layer; and

dicing the semiconductor wafer into a plurality of semiconductor substrates.

19. The method according to claim 18, wherein the forming the adhesive layer and the low refractive index layer includes:

forming the adhesive layer on the semiconductor wafer in a lattice configuration, and

forming the low refractive index layer by pouring the low-refractive-index material into a space partitioned by the adhesive layer.

20. The method according to claim 18, wherein the forming the adhesive layer and the low refractive index layer includes:

coating the low-refractive-index material over an entire surface of the semiconductor wafer;

forming the low refractive index layer by forming a groove in a lattice configuration in a coating layer made of the low-refractive-index material; and

forming the adhesive layer by pouring an adhesive into the groove.