KR19990076166A - Solid state imaging device manufacturing method - Google Patents

Abstract

The present invention is to provide a method for manufacturing a solid-state image pickup device for improving the resolution by forming light-shielding sidewalls on both sides of the polygate so that light does not penetrate the vertical charge transfer region, to form a light receiving region in a predetermined region on the substrate surface Forming a first polygate on the substrate with a first insulating film interposed therebetween; forming a second polygate on the first polygate with a second insulating film interposed therebetween; After forming a third insulating film on the surface of the second polygate, depositing a light blocking material on the entire surface including the substrate, patterning the light blocking material, and forming the third insulating film on both sides of the first and second polygates. Forming sidewalls with the gaps formed therebetween, and forming a light shielding layer on the fourth insulating film after forming a fourth insulating film on the entire surface including the sidewalls. It characterized by comprising.

Description

Solid state imaging device manufacturing method

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charge coupled device (CCD), and more particularly, to a method for manufacturing a solid state imaging device suitable for removing smear phenomenon by forming silicide on both sides of a polygate.

In general, a solid state image pickup device includes a photodiode region PD for converting a signal of light into electrical signal charge, and a vertical charge transfer region VCCD for shifting photoelectrically converted signal charges formed in a direction perpendicular to the photodiode region. And a horizontal charge transfer region HCCD transferring signal charges transferred through the vertical charge transfer region VCCD to the sensing amplifier SA.

In the solid state image pickup device, the signal charge generated by the photoelectric conversion in the photodiode region is moved to the horizontal charge transfer region by the vertical charge transfer region, and the transferred signal charge is applied to the clock signal applied to the polygate (not shown). Is transmitted to the sensing amplifier.

As shown in FIG. 2, the solid state image pickup device includes a photodiode according to a clock signal applied by overlapping the first polygate 13 and the second polygate 15 on the vertical charge transfer region VCCD. The signal charge of the region PD is transferred to the horizontal charge transfer region HCCD.

At this time, although not shown in the drawing, a light shielding layer is formed so that light is not transmitted to a region other than the photodiode region PD, and a microlens (not shown) is formed on the photodiode region PD to condense the light. .

Hereinafter, a conventional solid state imaging device manufacturing method will be described with reference to the accompanying drawings.

3A to 3D are cross-sectional views taken along line II ′ of FIG. 2, illustrating a conventional method of manufacturing a solid state image pickup device.

As shown in FIG. 3A, after the photodiode region PD is formed in a predetermined region on the surface of the substrate 11, the oxide-nitride-oxide-oxide structure is formed on the substrate 11 including the photodiode region PD. 1 An insulating film 12 is formed.

After the polysilicon layer is formed on the first insulating layer 12, the polysilicon layer 13 is patterned to remain in a predetermined region on the substrate 11 using a photolithography process to form the first polygate 13.

As shown in FIG. 3B, the second insulating film 14 is grown on the surface of the first polygate 13 using an oxidation process.

Thereafter, a polysilicon layer for forming a second polygate is formed on the entire surface of the substrate 11 including the second insulating layer 14, and then a second insulating layer on the first polygate 13 is formed by using a photolithography process. The second polygate 15 is formed with the 14 interposed therebetween.

As shown in FIG. 3C, after the third insulating film 16 is grown on the surface of the second polygate 15 through an oxidation process, the fourth insulating film is formed on the entire surface of the substrate 11 including the third insulating film 16. (17), a high temperature low pressure dielectric (HLD) is deposited.

After that, as shown in FIG. 3D, a light shielding layer 18 is formed on the high temperature low pressure dielectric film 17 to prevent light from being transmitted to a region other than the photodiode region PD. The solid state imaging device manufacturing process is completed.

However, the conventional solid-state imaging device manufacturing method as described above, even if a light shielding layer is formed to prevent light from being transmitted to the vertical charge transfer region, the light is not irradiated vertically, but is irradiated obliquely or by reflection and refraction by the light blocking layer. The high temperature low pressure dielectric film penetrates into the vertical charge transfer region under the first polygate to cause smear phenomenon.

Here, the smear phenomenon refers to a phenomenon in which signal charge is transferred to the vertical charge transfer region and the tail is pulled in the vertical direction on the screen, which may cause a decrease in resolution.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and provides a solid state image pickup device manufacturing method suitable for preventing sidewall light from penetrating into the vertical charge transfer region by forming sidewalls on both sides of the first polygate and the second polygate. Its purpose is to.

1 is a plan view of a general solid state imaging device

2 is a layout diagram of a solid state image pickup device showing a first polygate and a second polygate formed on a vertical charge transfer region;

3A through 3D are cross-sectional views illustrating a method of manufacturing a conventional solid-state imaging device according to line II ′ of FIG. 2.

4A to 4D are cross-sectional views illustrating a method of manufacturing a solid state image pickup device of the present invention.

Explanation of symbols for main parts of the drawings

11 substrate 12 first insulating film

13 first polygate 14 second insulating film

15 second polygate 16 third insulating film

17: fourth insulating film 18: light shielding layer

21 shading material 21a side wall

A solid-state imaging device manufacturing method of the present invention for achieving the above object comprises the steps of forming a light receiving region in a predetermined region on the substrate surface, and forming a first polygate with a first insulating film on the substrate; And forming a second polygate on the first polygate with a second insulating film interposed therebetween, forming a third insulating film on the surface of the second polygate, and then applying a light blocking material to the entire surface including the substrate. Forming a sidewall with the third insulating film interposed between the first and second polygates by patterning the light blocking material; and forming a fourth insulating film on the entire surface including the sidewall. And forming a light shielding layer on the fourth insulating film.

Hereinafter, a solid state image pickup device manufacturing method of the present invention will be described with reference to the accompanying drawings.

4A to 4D are process cross-sectional views for explaining the method for manufacturing a solid state image pickup device of the present invention.

As shown in FIG. 4A, after a light receiving region, that is, a photodiode region PD is formed in a predetermined region on the surface of the substrate 11, an oxide film-nitride film- is formed on the substrate 11 including the photodiode region PD. A first insulating film 12 having a laminated structure of oxide films is formed.

After the polysilicon layer is formed on the first insulating layer 12, the polysilicon layer 13 is patterned to remain only in a predetermined portion on the substrate 11 through a photolithography process.

After the second insulating film 14 is grown on the surface of the first polygate 13 through an oxidation process, a polysilicon layer for forming the second polygate is formed on the entire surface of the substrate 11 including the second insulating film 14. Form.

Subsequently, the polysilicon layer is patterned through a photolithography process to form a second polygate 15 on the first polygate 13 with the second insulating layer 14 interposed therebetween.

When the second insulating film 14 is grown, the third insulating film 16 is grown on the surface of the second polygate 15 using an oxidation process in the same manner.

Thereafter, as illustrated in FIG. 4B, a light blocking material 21 capable of blocking light may be deposited on the entire surface of the substrate 11 including the third insulating layer 16.

In this case, a tungsten silicide layer is used as the light blocking material 21.

The sidewalls 21a are formed on both sides of the first polygate 13 and the second polygate 15 by an etchback process with the second insulating layer 14 and the third insulating layer 14 interposed therebetween.

Here, any material capable of blocking light may be used in addition to the tungsten silicide layer used as the sidewall 21a.

Thereafter, as shown in FIG. 4C, after depositing the high temperature low pressure dielectric film as the fourth insulating film 17 on the entire surface of the substrate 11 including the sidewall 21a, as shown in FIG. 4D, the fourth insulating film ( Forming a light shielding layer 18 to prevent light transmission on the surface 17), the solid-state imaging device manufacturing process according to the present invention is completed.

As described above, the solid-state imaging device manufacturing method of the present invention has the following effects.

By forming sidewalls that block light transmission on both sides of the first polygate and the second polygate, the horizontally irradiated light does not penetrate into the vertical charge transfer region, thereby preventing smearing, thereby improving resolution.

Claims (3)

Forming a light receiving region in a predetermined region within the substrate surface; Forming a first polygate on the substrate with a first insulating film interposed therebetween; Forming a second polygate on the first polygate with a second insulating film interposed therebetween; Forming a third insulating film on the surface of the second polygate, and then depositing a light blocking material on the entire surface including the substrate; Patterning the light blocking material to form sidewalls on both sides of the first and second polygates with the third insulating film interposed therebetween; And forming a light shielding layer on the fourth insulating film after forming a fourth insulating film on the entire surface including the sidewalls. The method of claim 1, The light blocking material is a solid-state imaging device manufacturing method characterized in that to apply all materials that can block the light other than the tungsten silicide layer or the tungsten silicide layer. The method of claim 1, And the second insulating film and the third insulating film are formed by an oxidation process.