JP3008163B2 - Solid-state imaging device and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a solid-state imaging device, and more particularly to a solid-state imaging device capable of preventing smear and improving sensitivity, and a method of manufacturing the same.

[0002]

2. Description of the Related Art FIGS. 1A and 1B are sectional views of a conventional solid-state imaging device. Referring to FIG. 1A, the structure of a conventional solid-state imaging device is as follows. First and second p ^- type wells 11 and 12 are formed on an n-type substrate 10, and n ⁺ -type wells are formed in the first and second p ^- type wells 11 and 12, respectively ^.
Photodiode 14 and n ⁺ -type V as a charge transfer region
The CCD region 15 is formed, and the n ⁺ type photodiode 1
A p ⁺⁺ type surface isolation layer 16 is formed on the surface of the substrate 4, and a third p ^- type well 13 is formed below the n ⁺ type VCCD 15 so as to surround the same. the p ⁺ -type channel stop region 17 is formed between the photodiode and one of the VCCD region. Then, a gate insulating film 18 is formed on the entire surface of the substrate, and the transfer gate 1 is formed on the gate insulating film 18 in the VCCD region 15.
9, an interlayer insulating film 20, and a light shielding film 21 are sequentially formed,
A protective film 22 is formed on the entire surface of the substrate. Further protective film 2
2, a first flattening layer 23 is formed on the photodiode 14, a color filter layer 24 is formed on the first flattening layer 23 on the photodiode 14, and the first flattening layer 23 including the color filter layer 24 is formed. A second planarization layer 25 is formed thereon. A microlens 26 is formed on the second flattening layer 25 above the color filter layer 24.

In the conventional solid-state imaging device, light incident through a camera lens is focused by a microlens 26 and passes through a color filter layer 24. The light selectively transmitted through the color filter layer 24 enters the photodiode 14 and is photoelectrically converted into a charge. Therefore, the charge generated from the photodiode by the photoelectric conversion is transferred to the VCCD region 15 and then vertically transferred to an HCCD (not shown) by the clock signal of the VCCD region 15. HCC
The charge transferred to D is horizontally transferred by the HCCD clock signal, and the charge transferred horizontally by floating diffusion at the terminal of the element is sensed as a voltage, amplified, and transferred to peripheral circuits.

[0004]

However, in the conventional solid-state imaging device, as can be seen from FIG. 1B, of the light incident on the microlens 26, the light incident on the central portion of the microlens is the photodiode 14. , And is photoelectrically converted into signal charges. Light incident on the periphery of the microlens is incident on the VCCD region 15 and is a main factor causing a smear phenomenon. In the case of long-wavelength light, there is also a problem that light incident through the microlens 26 passes through the photodiode and enters the first p ⁻ -type well 11, generating undesired signal charges. there were. In addition, there is a problem that a step is formed above the photodiode and the VCCD.

An object of the present invention is to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a solid-state imaging device capable of improving the light sensitivity of a photodiode and a method of manufacturing the same. . Another object of the invention is to provide
An object of the present invention is to provide a solid-state imaging device capable of preventing smear by preventing light converging through a microlens from condensing only in a photodiode region, and a method of manufacturing the same.

[0006]

According to a first aspect of the present invention, there is provided a solid-state imaging device having a first conductive type substrate having a convex portion and a first conductive type formed in the substrate excluding the convex portion. A charge transfer region of a mold, a light detection region formed on a convex portion of the substrate and having a convex lens-shaped upper surface, a light concentration impurity region of a second conductivity type formed on an upper surface of the light detection region, and a light detection region. A gate insulating film formed on the substrate excluding the region, a transfer gate formed on the gate insulating film, a flattening layer formed on the substrate including the transfer gate, and a flattening layer on the photodiode; And a microlens formed on the substrate. The method includes the steps of: etching a substrate of a first conductivity type to form a protrusion; and ion-implanting an impurity of the first conductivity type into the substrate excluding the protrusion. To form a first conductivity type charge transfer region Forming a gate insulating film and a transfer gate sequentially on the substrate above the charge transfer region; and ion-implanting a first conductivity type impurity into the convex portion of the substrate using the transfer gate as a mask, thereby forming an upper portion. Forming a light detection region having a bulging curved surface and ion-implanting a second conductivity type high concentration impurity into the light detection region to form a second conductivity type high concentration impurity region on the surface of the light detection region; Forming a planarizing layer over the entire surface of the substrate; and forming a microlens on the planarizing layer above the photodiode.

[0007]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. 2A and 2B are cross-sectional views of a solid-state imaging device according to an embodiment of the present invention. Referring to FIG. 2A, in the solid-state imaging device of the present invention, first and second p ⁻ -type wells 31 and 32 are formed on an n-type substrate 30, and the first p ⁻ -type well 31 is A photodiode 34 having a swelling curved upper surface is formed, and a VCCD region 35 serving as a charge transfer region is formed in the second p ⁻ -type well 32. Photodiode 34
A p ⁺⁺ type surface isolation layer 36 is formed on the bulged upper surface, and a gate insulating film 38, a transfer gate 39, and a light shielding film 41 are formed on the substrate except for the bulged upper surface of the photodiode. An interlayer insulating film 40 is formed between the gate 39 and the light shielding film 41. A protective film 42 is formed over the entire surface of the substrate, a first planarization layer 43 is formed on the protective film 42, and a color filter layer 44 is formed on the first planarization layer 43 above the photodiode. First planarization layer 4 including color filter layer 44
A second flattening layer 45 is formed on 3, and a microlens 46 is formed on the second flattening layer 45 above the color filter layer.

In the solid-state image pickup device of the present invention having the above-described structure, the photodiode 34 has a shape like a microlens formed by swelling the upper surface. The light receiving area for receiving the light increases. Further, since the photodiode is formed in the shape of a convex lens, the distance between the microlens and the photodiode is reduced, and the light focused through the microlens 46 is transmitted to the photodiode 34 as shown in FIG. In addition to focusing only light, long-wavelength light also enters only the photodiode region, so that a conventional smear phenomenon or the like can be prevented. In addition, since the upper surface of the photodiode is formed in a convex lens shape and the step between the photodiode and the upper part of the VCCD region is improved, the subsequent process is easy.

FIG. 3 to FIG. 5 are views showing the manufacturing process of the solid-state imaging device of the present invention having the above structure. As shown in FIG.
First and second p ⁻ -type wells 31 and 3 are formed on an n-type substrate 30.
2 are sequentially formed, a substance for microlenses is applied to the entire surface of the substrate, and is patterned to leave the substance 51 for microlenses only on the substrate on the first p ⁻ -type well 31. At this time, the first p ⁻ -type well 31 is formed by implanting p ⁻ -type impurities into the substrate 30 by primary ion implantation, and the second p ⁻ -type well 32 is formed.
Is formed by implanting a p ^- type impurity into the portion other than the first p ^- type well 31 by secondary ion implantation. The second p ^- type well 32 has a larger junction than the first p ^- type well 31. With depth.

When the microlens material 51 is heated at a temperature of 100 to 200 ° C., a microlens 52 is formed on the substrate above the first p ⁻ -type well 31 as shown in FIG. . When the substrate on which the microlenses 52 are formed is dry-etched so that all the microlenses 52 are etched, the substrate has lens-shaped convex portions 30-1 as shown in FIG. At this time, the projection 30-1 of the substrate is a portion where a photodiode is to be formed in a subsequent process.

As shown in FIG. 3D, a p ⁺ type channel stop 37 for separating pixels from each other is formed.
Next, as shown in FIG.
Then, a third p ^-- type well 33 and an n ⁺ -type VCCD 35 are formed by ion-implanting p ^-- type impurities and n ⁺ -type impurities.

As shown in FIG. 4 (F), a gate insulating film 38 composed of an oxide film and a nitride film is formed on the substrate except for the projection 30-1, and a polysilicon film is deposited on the entire surface of the substrate and patterned. Transfer gate 3 on the gate insulating film 38
9 is formed.

[0013] As shown in FIG. 4 (G), the n ⁺ -type impurity ions are implanted to form the n ⁺⁺ type photodiode 34 to the convex portion 30-1 of the substrate transfer gate 39 as a mask, then the transfer gate Using the mask 39 as a mask, p ⁺⁺ -type impurities are ion-implanted into the photodiode 34 to form a p ⁺⁺ -type surface isolation layer 36 on the surface of the photodiode 34.

As shown in FIG. 5H, the photodiode 3
An interlayer insulating film 40 is formed on the transfer gate 39 excluding the swollen upper surface of the substrate 4, and a metal film is deposited and patterned over the entire surface of the substrate to form a light shielding film 4 on the insulating film 40.
Form one.

As shown in FIG. 5I, a protective film 42 is formed by depositing a nitride film over the entire surface of the substrate.
Is formed, and a color filter layer 44 is formed on the first flattening layer 43 above the photodiode 34.

Finally, a second flattening layer 45 is formed on the first flattening layer 43 including the color filter layer 44,
The microlens 4 is formed on the second flattening layer 45 on the color filter layer 44 by a normal microlens forming process.
When 6 is formed, the solid-state imaging device according to the embodiment of the present invention is manufactured.

[0017]

According to the present invention, the following effects can be obtained. 1. By forming the photodiode in a microlens shape, the light receiving area of the photodiode can be made larger than that of a conventional solid-state imaging device, and the light sensitivity can be improved. 2. The step in the upper part of the photodiode and the VCCD can be improved and the subsequent process can be easily performed. 3. By forming the photodiode in a swelling form, the distance between the microlens and the photodiode can be further reduced in the conventional solid-state imaging device. Therefore, by causing all the light focused on the microlens including the long wavelength light to enter only the photodiode, the occurrence of the smear phenomenon can be completely suppressed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a conventional solid-state imaging device.

FIG. 2 is a cross-sectional view of the solid-state imaging device according to one embodiment of the present invention.

FIG. 3 is a manufacturing process diagram of the solid-state imaging device of the present invention in FIG. 2;

FIG. 4 is a manufacturing process diagram of the solid-state imaging device of the present invention in FIG. 2;

FIG. 5 is a manufacturing process diagram of the solid-state imaging device of the present invention in FIG. 2;

[Explanation of symbols]

30 silicon substrate, 31-33 p-type well, 34
Photodiode, 35 ... Charge transfer area (VCCD),
36 ... p ⁺⁺ type surface isolation layer, 37 ... p ⁺ type channel stop region, 38 ... gate insulating film, 39 ... transfer gate, 40 ... interlayer insulating film, 41 ... light shielding film, 42 ... protective film, 43, 45 ... Flattening layer, 44 ... color filter layer,
46 ... Micro lens.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-3313 (JP, A) JP-A 64-35966 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 27/14 H01L 27/148 H01L 31/10

Claims (7)

(57) [Claims] A first conductive type charge transfer region formed in a semiconductor substrate; a gate insulating film formed on the charge transfer region; a transfer gate formed on the gate insulating film; A light detection region formed on a semiconductor substrate and having a portion protruding in a convex lens shape, and an insulating film interposed in a state where the portion of the light detection region protruding in a convex lens shape is exposed almost above the transfer gate. A light-shielding film formed by: a second conductive type surface separation layer formed on the upper surface of the photodetection region; and a micro-layer formed by interposing an insulating layer on the second conductive type surface separation layer. A lens, wherein the semiconductor substrate has a first conductivity type semiconductor layer having a projection below the light detection region, and a second conductivity type semiconductor formed on the first conductivity type semiconductor layer. Equipped with layers A solid-state imaging device, characterized in that. 2. The apparatus according to claim 1, further comprising a color filter layer formed above the light detection area.
The solid-state imaging device according to any one of the preceding claims. 3. The solid-state imaging device according to claim 1, wherein an upper surface of the light detection region is formed higher than the charge transfer region. 4. A step of forming a projection by etching a substrate of the first conductivity type, and ion-implanting impurities of the first conductivity type into the substrate excluding the projection to form a charge transfer region of the first conductivity type. Forming a gate insulating film and a transfer gate sequentially on the substrate above the charge transfer region; ion-implanting a first conductivity type impurity into a convex portion of the substrate using the transfer gate as a mask; Forming a photodetection region having a curved surface with bulging; ion-implanting a second conductive type high concentration impurity into the photodetection region to form a surface isolation layer on the surface of the photodetection region; Forming a flattening layer over the photodiode, and forming a microlens on the flattening layer above the photodiode. 5. The step of forming a projection on the substrate includes the step of applying a substance for microlenses on the substrate and the step of patterning the substance for microlenses to apply the substance for microlenses only to a portion corresponding to a light detection region. Leaving step, heat-flowing the material for microlenses to form microlenses on the substrate, dry-etching the substrate to remove the microlenses, and forming protrusions in the portions where the microlenses have been removed 5. The method for manufacturing a solid-state imaging device according to claim 4, comprising: 6. The method according to claim 4, further comprising, after the step of forming a transfer gate, forming a light-shielding film on the substrate excluding the light detection region. . 7. The solid-state imaging device according to claim 4, further comprising a step of forming a color filter layer on the flattening layer above the light detection area after performing the step of forming the flattening layer. Manufacturing method.