KR20100078104A

KR20100078104A - Method for manufacturing an image sensor

Info

Publication number: KR20100078104A
Application number: KR1020080136262A
Authority: KR
Inventors: 강성현
Original assignee: 주식회사 동부하이텍
Priority date: 2008-12-30
Filing date: 2008-12-30
Publication date: 2010-07-08

Abstract

PURPOSE: A method for manufacturing an image sensor is provided to improve image quality by protecting poly silicon of a gate electrode formed on a substrate. CONSTITUTION: Poly silicon and an oxide film(80) are formed on a semiconductor substrate(10). A first photo resist pattern is formed for etching the poly silicon and the oxide film. The oxide film and the poly silicon are etched by using a first photo resist pattern. A second photo resist pattern is formed on the semiconductor substrate and the oxide film for implanting an ion. A photo diode region is formed on the semiconductor substrate by performing an ion implantation process using the second photo resist pattern as an ion implantation mask.

Description

Method for manufacturing an image sensor

This embodiment discloses a method of manufacturing an image sensor.

Recently, with the development of semiconductor manufacturing technology, semiconductor devices for converting images into electric signals have been developed. An image sensor is a representative semiconductor device for electrically converting an image. Representative image sensors include charge coupled device (CCD) devices and CMOS image devices. The CCD device includes a plurality of MOS capacitors, which are operated by moving carriers generated by light. On the other hand, the CMOS image element includes a plurality of unit pixels and CMOS logic circuit for controlling the output signal of the unit pixel.

Also, in recent years, apart from the conventional method of arranging one color of red-green-blue in one pixel (pixel), all three colors are arranged vertically in one pixel. A vertical image sensor has been developed that can realize about three times higher image quality than a horizontal image sensor.

Since a variety of colors can be expressed without a separate color filter process of the vertical image sensor, there is an advantage of increasing productivity and reducing production cost.

The conventional vertical image sensor manufacturing method can be largely divided into two stages: forming a red photodiode and a green photodiode and forming a blue photodiode.

In particular, the ion implantation process for forming the blue photodiode was performed after patterning the polysilicon on the substrate, which is followed by a variety of by-products that can occur in the polysilicon patterning process for forming the gate electrode There is a problem that can act as a defect in diode formation.

In addition, even when the photoresist is applied on the polysilicon during the ion implantation process for forming the blue photodiode, there is a problem in that the polysilicon is damaged by the ion implantation process.

The present embodiment is proposed to solve the above problems, and discloses a method of manufacturing an image sensor capable of protecting polysilicon of a gate electrode formed on a substrate by a process of implanting ions into a semiconductor substrate.

A method of manufacturing an image sensor according to the present embodiment includes forming polysilicon and an oxide film on a semiconductor substrate; Forming a first photoresist pattern for etching the polysilicon and the oxide film; Etching the oxide film and the polysilicon using the first photoresist pattern as an etching mask; Forming a second photoresist pattern for ion implantation on the semiconductor substrate and the oxide film; And forming a photodiode region on the semiconductor substrate by performing an ion implantation process using the second photoresist pattern as an ion implantation mask.

In addition, the manufacturing method of the image sensor of the embodiment comprises the steps of forming a first epitaxial layer on the semiconductor substrate, the red photodiode on the first epitaxial layer; Forming a second epitaxial layer on the first epitaxial layer, and forming a green photodiode and a first plug on the second epitaxial layer; Forming a third epitaxial layer on the second epitaxial layer and forming an isolation layer on the third epitaxial layer; Forming polysilicon for forming a gate electrode on the third epitaxial layer, and forming an oxide film on the polysilicon; Forming a first photoresist pattern on the oxide film and etching the oxide film and polysilicon; Forming a second photoresist pattern on the third epitaxial layer and the oxide film, and forming a blue photodiode on the third epitaxial layer; And forming a second plug isolated from the device isolation layer.

According to the embodiment as described above, it is possible to prevent damage to the polysilicon during the ion implantation process for forming the photodiode, thereby improving the image quality.

Hereinafter, with reference to the accompanying drawings for the present embodiment will be described in detail. However, the scope of the idea of the present invention may be determined from the matters disclosed by the present embodiment, and the idea of the invention of the present embodiment may be performed by adding, deleting, or modifying components to the proposed embodiment. It will be said to include variations.

In the following description, the word 'comprising' does not exclude the presence of other elements or steps than those listed.

And, for the detailed description of the embodiment of the present invention, each part constituting the image sensor is shown partially enlarged, which needs to be referred to.

1 to 10 are views for explaining the manufacturing method of the image sensor according to the present embodiment.

First, referring to FIG. 1, after forming a first epitaxial layer 20 on a semiconductor substrate 10, for example, a P-type semiconductor substrate, an N-type impurity such as arsenic (As) may be formed on the first epitaxial layer. Ions are implanted to form a red photodiode (R).

Subsequently, boron ions are implanted between the red photodiodes to form an insulation region (not shown).

Next, referring to FIG. 2, after forming the second epitaxial layer 30 on the first epitaxial layer 20, N-type impurity ions are implanted into the second epitaxial layer again to form a green photodiode G. ) And boron ions are implanted between the green photodiodes (G) to form an insulating region (not shown).

Subsequently, high energy ions are implanted into the second epitaxial layer 30 to form a first plug 50.

Next, referring to FIG. 3, after forming the third epitaxial layer 40 on the second epitaxial layer 30, the third epitaxial layer 40 may be formed to separate the device isolation region from the active region. The device isolation region forming process is performed to form the device isolation layer 60.

In this case, the device isolation layer may be formed by an STI process.

Next, referring to FIG. 4, polysilicon 70 for forming a gate electrode is formed on the third epitaxial layer 40, and an oxide film 80 having a predetermined thickness is formed on the polysilicon 70. Vapor deposition.

In this case, the oxide film 80 serves as a blocking layer for polysilicon in a subsequent high energy ion implantation process, and may be formed to have a thickness in the range of 1000 to 2000 microns.

Next, referring to FIG. 5, a photoresist pattern 90 corresponding to a gate electrode to be formed on the oxide film 80 is coated, and the oxide film (using the photoresist pattern 90 as an etching mask) is applied. 80) and the polysilicon 70 are etched.

After the etching process of the oxide layer 80 and the polysilicon 70 is performed, a cleaning process of removing the photoresist pattern 90 is performed. As a result, a gate electrode 71 having a shape as shown in FIG. 6 is formed, and an oxide film 80 is formed on an upper surface of the gate electrode 71.

Here, the cleaning process of removing the photoresist pattern 90 may be rinsed 140 with DI. This DI rinse may be performed before or after forming the photoresist pattern, and may be subjected to an ashing process to remove residues of the photoresist.

For example, when oxygen gas (O ₂ ) is flowed and heated to a temperature of 110 to 130 ° C., oxygen gas and carbon (C) of the PR component react to vaporize with carbon monoxide (CO), carbon dioxide (CO ₂ ), or the like. Can be removed.

Next, referring to FIG. 7, a photoresist pattern 100 for forming a blue photodiode is formed on the third epitaxial layer 40 and the gate electrode.

Here, a part of the photoresist pattern 100 is positioned on the oxide film 80 formed on the upper surface of the gate electrode 71, and the photoresist pattern 100 coated on the oxide film 80 is formed. A portion of the oxide film 80 may be exposed.

When the upper surface of the gate electrode 71 is completely covered by the photoresist pattern 100, a portion of the photoresist may remain on the surface of the third epitaxial layer 40. The photoresist pattern 100 may be formed to expose a portion of the upper surface of the oxide film 80.

That is, the photoresist pattern 100 is formed on a portion of the upper surface of the gate electrode 71, and a portion of the upper surface of the gate electrode 71 may be exposed before the ion implantation process.

Then, using the photoresist pattern 100 as an ion implantation mask, a blue photodiode B '(see FIG. 8) is formed on the surface of the third epitaxial layer 40. After the ion implantation process for forming the blue photodiode B 'is performed, the photoresist pattern formed on the oxide film 80 is removed.

Next, referring to FIG. 9, an etching process for removing the oxide film 80 formed on the upper surface of the gate electrode 71 is performed. An etching process for removing the oxide film 80 is performed by using hydrogen peroxide (H _2). O ₂ ) may be performed by a cleaning process using.

In addition, spacers are formed on both sides of the gate electrode 71, and P-type impurity ions are implanted into the surface of the third epitaxial layer 40 so that P-type impurity ions are implanted on the blue photodiode B ′. The cover layer 110 may be formed.

Next, referring to FIG. 10, high energy P-type impurity ions are implanted in the second plug formation process by using a mask covering a portion of the device isolation layer 60 and a portion of the peripheral region as an ion implantation mask. The second plug 120 is connected to the P + type first plug 50 or to the P + type green photodiode G.

Then, although not shown, a general subsequent process is followed to produce the image sensor.

Claims

Forming a polysilicon and an oxide film on the semiconductor substrate;

Forming a first photoresist pattern for etching the polysilicon and the oxide film;

Etching the oxide film and the polysilicon using the first photoresist pattern as an etching mask;

Forming a second photoresist pattern for ion implantation on the semiconductor substrate and the oxide film; And

And forming a photodiode region on the semiconductor substrate by performing an ion implantation process using the second photoresist pattern as an ion implantation mask.

The method of claim 1,

And the second photoresist pattern is formed to expose a portion of the oxide film and a semiconductor substrate in a region in which the photodiode is to be formed.

The method of claim 1,

The oxide film is a manufacturing method of the image sensor, characterized in that formed in a thickness in the range of 1000 to 2000Å.

Forming a first epitaxial layer on the semiconductor substrate, and forming a red photodiode on the first epitaxial layer;

Forming a second epitaxial layer on the first epitaxial layer, and forming a green photodiode and a first plug on the second epitaxial layer;

Forming a third epitaxial layer on the second epitaxial layer and forming an isolation layer on the third epitaxial layer;

Forming polysilicon for forming a gate electrode on the third epitaxial layer, and forming an oxide film on the polysilicon;

Forming a first photoresist pattern on the oxide film and etching the oxide film and polysilicon;

Forming a second photoresist pattern on the third epitaxial layer and the oxide film, and forming a blue photodiode on the third epitaxial layer; And

And forming a second plug isolated from the device isolation layer.

The method of claim 4, wherein

And after the etching process of the oxide film and the polysilicon using the first photoresist pattern is performed, a cleaning process using a DI rinse is performed.

The method of claim 4, wherein

After the ion implantation process for forming the blue photodiode is performed, a process for removing the second photoresist pattern and an etching process for removing the oxide layer are further performed. Way.

The method of claim 4, wherein

The forming of the oxide film may include forming the oxide film to a thickness in a range of 1000 to 2000 kV.