Photosensor and photo IC equipped with same

• US 7,935,934 B2
• Filed: 12/26/2008
• Issued: 05/03/2011
• Est. Priority Date: 01/15/2008
• Status: Active Grant

• Current Assignee: LAPIS Semiconductor Co., Ltd. (ROHM Co., Ltd.)
• Original Assignee: Oki Semiconductor Company Limited (ROHM Co., Ltd.)
• Inventors: Komatsubara, Hirotaka
• Primary Examiner(s): Porta; David P
• Assistant Examiner(s): Baker; David S
• Application Number:
  US12/344,400
• Publication Number:
  US 20090179156A1
• Time in Patent Office: 858 Days
• Field of Search: 250/372
• US Class Current: 250/372
• CPC Class Codes: G01J 1/02 Details
• CPC Class Codes: G01J 1/0204 Compact construction
• CPC Class Codes: G01J 1/0209 Monolithic
• CPC Class Codes: G01J 1/1626 Arrangements with two photodetectors, the signals of which are compared
• CPC Class Codes: G01J 1/429 applied to measurement of ultraviolet light using counting tubes G01T
• CPC Class Codes: H01L 31/103 the potential barrier being of the PN homojunction type

Abstract

The photosensor comprises an insulating layer formed over the silicon substrate; an ultraviolet photosensitive element formed over the insulating layer and having a first diffusion layer, a second diffusion layer provided spaced away from the first diffusion layer, and a third diffusion layer connected with the first diffusion layer and the second diffusion layer respectively; and a visible light photosensitive element formed over the insulating layer with being spaced away from the ultraviolet photosensitive element, and having a fourth diffusion layer, a fifth diffusion layer provided spaced away from the fourth diffusion layer, and a sixth diffusion layer connected with the fourth diffusion layer and the fifth diffusion layer respectively.

Claims

1. A photosensor comprising:

a silicon substrate;

an insulating layer formed over the silicon substrate;

an ultraviolet photosensitive element formed over the insulating layer and having a first diffusion layer having a first conductivity type, a second diffusion layer provided spaced away from the first diffusion layer and having a second conductivity type opposite to the first conductivity type, and a third diffusion layer connected with the first diffusion layer and the second diffusion layer respectively and having the first conductivity type; and

a visible light photosensitive element formed over the insulating layer with being spaced away from the ultraviolet photosensitive element, said visible light photosensitive element having a fourth diffusion layer having a third conductivity type, a fifth diffusion layer provided spaced away from the fourth diffusion layer and having a fourth conductivity type opposite to the third conductivity type, and a sixth diffusion layer connected with the fourth diffusion layer and the fifth diffusion layer respectively and having the third conductivity type,

wherein the thickness of the third diffusion layer of the ultraviolet photosensitive element is smaller than that of the sixth diffusion layer of the visible light photosensitive element.

2. The photosensor according to claim 1, wherein the thickness of the third diffusion layer of the ultraviolet photosensitive element is smaller than the thicknesses of the first and second diffusion layers of the ultraviolet photosensitive element.

3. The photosensor according to claim 1, wherein thickness of the sixth diffusion layer of the visible light photosensitive element is larger than the thicknesses of the fourth and fifth diffusion layers of the visible light photosensitive element.

4. The photosensor according to claim 1, further including an element isolation layer which is formed over the insulating layer and surrounds the ultraviolet photosensitive element and the visible light photosensitive element.

5. The photosensor according to claim 1, wherein an impurity concentration of the third diffusion layer of the ultraviolet photosensitive element and an impurity concentration of the sixth diffusion layer of the visible light photosensitive element are different from each other.

6. The photosensor according to claim 1, wherein the first conductivity type and the third conductivity type are different conductivity types.

7. The photosensor according to claim 1, wherein the first conductivity type and the third conductivity type are of the same conductivity type.

8. A photo IC equipped with the photosensor according to claim 1, wherein a peripheral circuit for controlling the ultraviolet photosensitive element and the visible light photosensitive element is formed over the insulating layer.