KR20100078381A

KR20100078381A - Method of manufacturing image sensor

Info

Publication number: KR20100078381A
Application number: KR1020080136634A
Authority: KR
Inventors: 황선재
Original assignee: 주식회사 동부하이텍
Priority date: 2008-12-30
Filing date: 2008-12-30
Publication date: 2010-07-08

Abstract

The present invention relates to the fabrication of an image sensor, which is divided into a pixel region and a device region, in particular in semiconductor technology. Sequentially forming an insulating film and a first planarization film on the entire surface of the lower insulating film including a wiring pattern, forming a mask pattern for a via contact on the first planarization film, and using the mask pattern Forming a first via exposing the pad protection layer, forming a color filter, a second planarization film on the color filter, and a microlens on the second planarization film in a pixel area on the first planarization film; And etching the first via further by using the first planarization layer etched by the mask pattern as a mask. The invention is characterized in that the shipment consists of forming a second via.

Description

Method of manufacturing image sensor

TECHNICAL FIELD The present invention relates to semiconductor technology, and more particularly to a method of manufacturing an image sensor.

In general, an image sensor is a semiconductor device that converts an optical image into an electrical signal, and is largely a charge coupled device (CCD) and a CMOS (Complementary Metal Oxide Silicon) image sensor. It is divided into (Image Sensor) (CIS).

The CMOS image sensor forms an image by sequentially detecting an electrical signal of each unit pixel by a switching method by forming a photodiode and a MOS transistor in the unit pixel.

On the other hand, in the image sensor, in order to increase the light sensitivity, the fill factor of the photodiode in the total area of the image sensor is increased, or the path of the light incident to an area other than the photodiode is changed to focus on the photodiode. Giving techniques are used.

1 is a cross-sectional view showing an image sensor according to the prior art.

A photodiode exists in the semiconductor substrate, and an area in which the photodiode exists is defined as a pixel region.

There are several gate electrodes in the pixel region, including the transfer gate. An interlayer insulating film corresponding to pre-metal dielectic (PMD) is formed on the entire surface where the photodiode and the transfer gate are formed. Each layer having a multilayer structure of the interlayer insulating film includes a metal wiring. The interlayer insulating film also includes a via contact to complete the connection between the metal wires.

After the uppermost metal wiring 10 is formed in the above structure, a passivation layer 11 for protecting the underlying structure is formed on the entire lower interlayer insulating film including the uppermost metal wiring 10. Subsequently, a planarization film 13 is formed on the passivation layer, and in the pixel region, a color filter 14, another planarization film on the color filter 14, and a microlens 15 are provided on the planarization film.

Meanwhile, in the related art, via formation etching for pad opening is performed in order to prevent pad attack due to a fluorine component and a developing solution used during the process of forming the color filter 14 and the microlens 15. After the process, a photoresist or plasma-enhanced tetraethoxysilane (PE-TEOS) thin film was deposited to serve as a protective film.

However, the fluorine component remains in the via forming etching process, which causes a defect in the uniformity of the thin film of 10 to 30 nm. As a result, the attack of the metal pad occurred due to the developing solution used during the color filter or microlens formation process.

As a result, there is a possibility of a defect in the appearance of the metal pad, which also affected the overall yield of the image sensor.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing an image sensor suitable for eliminating attack of a metal pad caused by a developing solution used during a color filter or microlens forming process.

A feature of the image sensor manufacturing method according to the present invention for achieving the above object is, in the manufacture of an image sensor divided into a pixel region and a device region, a metal wiring, a protective film and a pad protective film laminated on the lower insulating film Forming a pattern, sequentially forming an insulating film and a first planarization film on the entire surface of the lower insulating film including the metal wiring pattern, and forming a mask pattern for via contact on the first planarization film And forming a first via exposing the pad protection layer using the mask pattern, a color filter in a pixel region on the first planarization layer, a second planarization layer on the color filter, and the Forming a microlens on a second planarization film, and using the first planarization film etched by the mask pattern as a mask for the first ratio A further etch, would comprising a step of forming a second blank (2nd Via) to expose the metal film.

According to the present invention, the silicon nitride film remains as a pad protective film even after the via forming etching process for opening the metal pad, thereby eliminating the occurrence of attack of the metal pad by the developing solution used during the formation process of the color filter or the microlens. This helps to improve the yield of the image sensor.

Other objects, features and advantages of the present invention will become apparent from the detailed description of the embodiments with reference to the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a configuration and an operation of an embodiment of the present invention will be described with reference to the accompanying drawings, and the configuration and operation of the present invention shown in and described by the drawings will be described as at least one embodiment, The technical idea of the present invention and its essential structure and action are not limited.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the image sensor manufacturing method according to the present invention.

2A through 2E are cross-sectional views illustrating an image sensor manufacturing process according to the present invention.

The image sensor of the present invention is divided into a pixel region in which a photodiode is formed and an element region around the pixel region.

In the above structure, as shown in FIG. 2A, an interlayer insulating film 100 corresponding to the lower insulating film including the lower metal wiring is formed, and a metal film connected to the lower metal wiring on the interlayer insulating film 100 ( 110, the passivation layer 120 is formed on the metal layer 110, and the pad passivation layer 130 is sequentially formed on the passivation layer 120. Subsequently, a first mask pattern 140 for upper metal wiring is formed on the pad protection layer 130. Here, the upper metal wiring may be a metal pad for electrical connection with an external device. The protective film 120 is formed of Ti / TiN, and the pad protective film 130 is formed of silicon nitride (SiN). For example, the passivation layer 120 is formed by depositing Ti / TiN to a thickness of 5 to 36 nm, the metal layer 110 forms an aluminum / copper alloy to a thickness of 640 nm, and the pad passivation layer 130 forms a silicon nitride layer. Deposit 30nm thick. Meanwhile, Ti / TiN may be further deposited on the lower portion of the metal film 110 to a thickness of 10 to 22 nm.

Next, the metal layer 110, the passivation layer 120, and the pad passivation layer 130 are etched using the first mask pattern 140.

Accordingly, as shown in FIG. 2B, an upper metal wiring pattern in which the etched metal film 110a, the passivation layer 120a, and the pad passivation layer 130a are stacked is formed. Here, the upper metal wiring pattern may be a metal pad pattern. Subsequently, the insulating layer 150 and the first planarization layer 160 including the upper metal wiring patterns 110a, 120a, and 130a may be sequentially formed on the entire surface of the interlayer insulating layer. Here, the first planarization film is formed of silicon nitride film (SiN).

Subsequently, as illustrated in FIG. 2C, a second mask pattern 170 for via contact is formed on the first planarization layer 160. Next, a first via is formed to expose the pad protective layer 130b etched using the second mask pattern 170. In this case, the passivation layer (Ti / TiN) 120a is not exposed. After forming the primary via, the thickness of the pad protective layer 130b may be 20 nm or less.

Subsequently, as shown in FIG. 2D, the color filter! 80, the second planarization film on the color filter 180, and the second planarization film are formed in the pixel region on the first planarization film 160a including the primary vias. The microlens 190 is formed.

Subsequently, as illustrated in FIG. 2E, the first via is further etched using the first planarization layer 160a etched by the second mask pattern 170 to expose the etched metal layer 110a. Form a 2nd Via.

As an example, the etching for forming the primary via may be performed for about 15 seconds using H ₂ PO ₄ as an etching solution, and the etching for the primary via is performed for about 30 seconds, and the pad protective layer 130b and the protective layer are left. (120a is etched at the same time.

While the preferred embodiments of the present invention have been described so far, those skilled in the art may implement the present invention in a modified form without departing from the essential characteristics of the present invention.

Therefore, the embodiments of the present invention described herein are to be considered in descriptive sense only and not for purposes of limitation, and the scope of the present invention is shown in the appended claims rather than the foregoing description, and all differences within the scope are equivalent to the present invention. Should be interpreted as being included in the

1 is a cross-sectional view showing an image sensor according to the prior art.

2A to 2E are cross-sectional views illustrating an image sensor manufacturing process according to the present invention.

Claims

In the manufacture of an image sensor divided into a pixel region and an element region,

Forming a metal wiring pattern on which a metal film, a protective film, and a pad protective film are stacked on the lower insulating film;

Sequentially forming an insulating film and a first planarization film on an entire surface of the lower insulating film including the metal wiring pattern;

Forming a mask pattern for a via contact on the first planarization layer;

Forming a first via exposing the pad protective layer using the mask pattern;

Forming a color filter, a second planarization film on the color filter, and a micro lens on the second planarization film in a pixel area on the first planarization film;

And etching the first via further by using the first planarization layer etched by the mask pattern as a mask to form a second via which exposes the metal layer.

The method of claim 1, wherein the pad protective layer and the first planarization layer are formed of a silicon nitride layer, and the protective layer is formed of Ti / TiN.

The method of claim 1, wherein the forming of the metallization pattern is performed.

Forming a lower insulating film including a lower metal wiring on a semiconductor substrate provided with a photodiode;

Sequentially depositing a metal on the lower insulating film, the Ti / TiN on the metal, and the silicon nitride on the Ti / TiN;

Forming a mask pattern on the silicon nitride;

And etching the metal, the Ti / TiN, and silicon nitride by using the mask pattern.