KR20070036528A - Image sensor and method for manufacturing the same - Google Patents

Abstract

The present invention is to provide an image sensor and a method of manufacturing the same, which can prevent the diffusion of the material forming the metal wiring while removing the noise of the image sensor including the metal wiring, for this purpose is formed on the substrate, An interlayer insulating film having a trench formed therein, a first diffusion barrier film formed along the inner surface of the trench, a metal interconnection formed to fill the trench, and a second diffusion barrier interposed between the metal interconnection and the first diffusion barrier layer. It provides an image sensor that includes.

Image sensor, metallization, diffusion barrier, tantalum oxide, noise.

Description

Image sensor and manufacturing method thereof {IMAGE SENSOR AND METHOD FOR MANUFACTURING THE SAME}

1 is a cross-sectional view for explaining a metal wiring forming method of an image sensor according to an embodiment of the prior art.

Figure 2 is a cross-sectional view for explaining a metal wiring forming method of the image sensor according to another embodiment of the prior art.

3 is a cross-sectional view showing an image sensor having a metal wiring according to a preferred embodiment of the present invention.

4A through 4E are cross-sectional views illustrating a method of forming metal wirings of an image sensor according to a preferred embodiment of the present invention.

-Explanation of symbols for the main parts of the drawings-

210: substrate

211: first interlayer insulating film

213: first diffusion barrier

215: oxygen plasma process

216: second diffusion barrier

217: physical sputtering process

218: metal wiring

219 metal capping layer

220: second interlayer insulating film

223: via hole

224 trench

The present invention relates to an image sensor and a method of manufacturing the same, and more particularly, to an image sensor having a copper metal wiring and a method for forming metal wiring of the image sensor.

Recently, many attempts have been made to reduce the interlayer thickness between metal wires in order to reduce noise in manufacturing an image sensor. One of them is to form copper (Cu) wiring using a damascene process. This is because copper maintains excellent wiring characteristics even at a thin thickness because copper has lower electrical conductivity than aluminum (Al).

However, since the formation of the wiring using copper generally uses a damascene process, an etching stop layer must be interposed when the metal wiring is formed. Usually, since the etch stop film uses a material having a refractive index different from that of the intermetallic dielectrics (IMD), this may also act as noise of the image sensor. Therefore, recently, a method of removing an etch stop film has been proposed to remove such noise. As such, there are two methods of removing the etch stop layer. For example, (1) minimizing the number by eliminating the formation of the etch stop film where the etch stop film is unnecessary, and (2) completely removing the etch stop film and using a metal capping layer instead.

1 is a cross-sectional view for explaining a metal wiring forming method of the image sensor according to the method of ①, Figure 2 is a cross-sectional view for explaining a metal wiring forming method of the image sensor according to the method of ②. Hereinafter, a method of forming metal wirings of an image sensor according to the related art will be described with reference to FIGS. 1 and 2.

Referring to Figure 1, the metal wire forming method of the image sensor according to an embodiment of the prior art is as follows. First, the first interlayer insulating film 11 is formed on the substrate 10 with the lower metal wiring 13 interposed therebetween, and then the etch stop film (on the first interlayer insulating film 11 including the lower metal wiring 13) is formed. 14) is deposited. Then, after the second interlayer insulating layer 15 is deposited on the etch stop layer 14, the upper metal wiring 19 is buried in via holes (not shown) and trenches (not shown) formed through a dual damascene process. do. In this case, the lower metal wiring 13 is formed so that the trench is buried on the diffusion barrier 12 that is first deposited along the inner surface of the trench (not shown) formed in the first interlayer insulating film 11. In addition, the upper metal wiring 19 is formed so that the via holes and the trenches are buried in the diffusion barrier layer 18 deposited along the inner surface of the via holes and the trenches formed in the second interlayer insulating layer 15.

However, according to the method of ① as shown in FIG. 1, although the number of the etch stop films is reduced, there is a problem in that the noise stop films cannot be completely removed.

Referring to FIG. 2, a metal wire forming method of an image sensor according to another embodiment of the prior art is as follows. First, the first interlayer insulating layer 21 is formed on the substrate 20 via the lower metal interconnection 23, and then the metal capping layer 24 is formed on the lower metal interconnection 23. Thereafter, the second interlayer insulating layer 25 without the etch stop layer is deposited on the first interlayer insulating layer 21 to cover the metal capping layer 24, and then the via hole 27 formed through a dual damascene process. And to form a trench 28. In this case, the lower metal wiring 23 is formed so that the trench is buried on the diffusion barrier 22 that is first deposited along the inner surface of the trench (not shown) formed in the first interlayer insulating layer 21.

However, according to the method of ② as shown in FIG. 2, since the etch stop film does not exist, the probability that the via hole 27 is misaligned with the lower metal wiring 23 is significantly formed. As such, in the misaligned portion, a damage (see 'A' portion) is applied to the first interlayer insulating layer 21 at the bottom of the via hole 27 and at the same time, the diffusion barrier layer is formed on both side walls of the lower metal wiring 23. Damage to (22) is also caused to cause diffusion of copper constituting the lower metal wiring 23. In particular, the conventional diffusion barrier 22 is made of Ta or TaN, which is easily etched by the fluoride gas used during the etching of the interlayer insulating film, thereby easily causing damage.

Such diffusion of copper causes a fatal problem including leakage current in a semiconductor device including an image sensor.

The present invention proposed to solve the problems of the prior art as described above, to provide an image sensor and a method of manufacturing the same that can prevent the diffusion of the material forming the metal wiring while removing the noise of the image sensor including the metal wiring. There is a purpose.

According to an aspect of the present invention, there is provided an interlayer insulating film formed on a substrate and having a trench formed therein, a first diffusion barrier film formed along an inner surface of the trench, and the trench embedded therein. Provided is an image sensor including a formed metal wiring, and a second diffusion blocking film interposed between the metal wiring and the first diffusion blocking film.

According to another aspect of the present invention, a trench is formed by etching a portion of an interlayer insulating film deposited on a substrate, and a first diffusion is performed along a step of an upper portion of the interlayer insulating film including the trench. Depositing a barrier layer, forming a second diffusion barrier layer on a surface of the first diffusion barrier layer, and forming the second diffusion barrier layer on a bottom surface of the trench such that the second diffusion barrier layer remains only on an inner wall of the first diffusion barrier layer And removing a second diffusion barrier layer, depositing a metal wiring in which the trench is buried, and planarizing the metal wiring so that a step with the interlayer insulating layer is removed.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the technical idea of the present invention. In addition, in the drawings, the thicknesses of layers and regions are exaggerated for clarity, and in the case where the layers are said to be "on" another layer or substrate, they may be formed directly on another layer or substrate or Or a third layer may be interposed therebetween. Also, throughout the specification, the same reference numerals denote the same components.

Example

3 is a cross-sectional view illustrating an image sensor having a metal wiring according to a preferred embodiment of the present invention.

Referring to FIG. 3, an image sensor according to a preferred embodiment of the present invention is formed on a substrate 210 and has an interlayer insulating film 211 having trenches (not shown) and a first diffusion formed along an inner surface of the trench. The barrier layer 213 includes a metal line 218 formed to fill the trench, and a second diffusion barrier 216 interposed between the metal line 218 and the first diffusion barrier 213. In addition, the metal capping layer 219 may be further included on the metal wire 218. Usually, the metal capping layer 219 is formed of tungsten (W) or cobalt (Co), and the metal wiring 218 is formed of copper.

Here, the first diffusion barrier 213 is formed of any one of Ta, TaN single layer and Ta / TaN laminated layer, and the second diffusion barrier 216 is formed of tantalum oxide formed by oxidizing them. Preferably, the second diffusion barrier 216 is formed only on the inner wall of the first diffusion barrier 213. Since the specific resistance of tantalum oxide constituting the second diffusion barrier 216 is very high, when the second diffusion barrier 216 is present on the upper portion of the first diffusion barrier 213, that is, at the bottom of the trench, the metal wiring 218 may be formed. This is because the contact resistance is increased. As a result, the second diffusion barrier 216 of the trench bottom is removed.

In addition, the second diffusion barrier 216 is formed to a thickness of 1 ~ 10nm.

That is, according to a preferred embodiment of the present invention, the first diffusion barrier layer formed of any one of Ta, TaN single layer and Ta / TaN laminated layer to prevent diffusion of the material forming the metal wiring 218, preferably copper ( By interposing the second diffusion barrier 216 made of tantalum oxide between the metal interconnection 213 and the metal interconnection 218, the first diffusion barrier 213 at the bottom of the via hole in the misaligned region with the metal interconnection 218 may be damaged. Even if it is possible to completely prevent the diffusion of the metal wiring 218 material. This is because the second diffusion barrier 216 made of tantalum oxide has a lower etching rate and a higher diffusion preventing rate of copper than Ta or TaN.

4A to 4E are cross-sectional views illustrating a method of forming metal wirings of an image sensor according to an exemplary embodiment of the present invention.

First, as shown in FIG. 4A, an interlayer insulating film 211 (hereinafter, referred to as a first interlayer insulating film) is deposited on the substrate 210. In this case, the first interlayer insulating film 211 is formed of an oxide-based material. For example, the first interlayer insulating film 211 may be a high density plasma (HDP) oxide film, a boron phosphorus silicate glass (BPSG) film, a phosphorus silicate glass (PSG) film, a plasma enhanced tetra orthysilicate (peteos) film, or plasma enhanced PECVD. Single layer film or lamination thereof using any one of Chemical Vapor Deposition (USG) film, USG (Un-doped Silicate Glass) film, Fluorinated Silicate Glass (FSG) film, Carbon Doped Oxide (CDO) film and Organic Silicate Glass (OSG) film It is formed into a laminated film.

Subsequently, a portion of the first interlayer insulating film 211 is etched by performing a mask process and an etching process to form a trench (not shown). Then, the first diffusion barrier layer 213 is deposited along the stepped portion of the first interlayer insulating layer 211 including the trench. For example, the first diffusion barrier 213 is deposited in the form of any one of Ta, TaN single layer, and Ta / TaN stacked layer.

Subsequently, as illustrated in FIG. 4B, an oxygen (O ₂ ) plasma process 215 is performed on the entire structure on which the first diffusion barrier layer 213 is deposited to oxidize the surface of the first diffusion barrier layer 213. As a result, tantalum oxide is formed on the surface of the first diffusion barrier layer 213 as the second diffusion barrier layer 216. Tantalum oxide has a property of not being easily etched into a fluoride gas used in etching a material, for example, silicon oxide, that forms the first interlayer insulating film 211. Accordingly, even if the first diffusion barrier 213 at the bottom of the via hole 223 (see FIG. 4E) formed through misalignment is damaged, diffusion of the material of the metallization 218 can be completely prevented.

Subsequently, as illustrated in FIG. 4C, a physical sputtering process 217 is performed to remove the second diffusion barrier 216 at the bottom of the trench (not shown). As a result, only the first diffusion barrier 213 remains at the bottom of the trench. This is to reduce the contact resistance of the metal wiring 218 (see FIG. 4D) to be subsequently buried in the trench.

Subsequently, as shown in FIG. 4D, the metal wiring 218 is deposited to fill the trench (not shown). Preferably, copper is deposited.

Subsequently, the first interlayer insulating layer 211 is formed as a planarization stop layer so that the first and second diffusion barrier layers 213 and 216 (see FIG. 4C) and the metal wiring 218 protruding from the first interlayer insulating layer 211 are removed. One planarization process is carried out. Preferably, the chemical mechanical polishing (CMP) process is performed to form the metal wiring 218 embedded only in the trench.

Subsequently, as shown in FIG. 4E, metal is deposited on the first interlayer insulating film 211 including the metal wiring 218 and then patterned to form a metal capping layer 219 on the metal wiring 218. do. For example, the metal capping layer 219 is formed of cobalt or tungsten.

Next, a second interlayer insulating film 220 is deposited on the first interlayer insulating film 211 to cover the metal capping layer 219. In this case, the second interlayer insulating film 220 is also formed of the same material as the first interlayer insulating film 211.

Subsequently, the via hole 223 and the trench 224 are formed in the second interlayer insulating film 220 by performing a dual damascene process.

Subsequently, although not shown in the drawings, as in the above-mentioned prior art, metal wirings for filling the via holes 223 and the trenches 224 are formed. In this case, the diffusion barrier layer may be deposited along the inner surfaces of the via hole 223 and the trench 224 before the metal wiring is formed.

Although the technical idea of the present invention has been described in detail according to the above preferred embodiment, it should be noted that the above-described embodiment is for the purpose of description and not of limitation. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical idea of the present invention.

As described above, according to the present invention, the first diffusion barrier layer formed of any one of Ta, TaN single layer and Ta / TaN laminated layer to prevent diffusion of a material forming the metal wiring of the image sensor, preferably copper; By interposing the second diffusion barrier layer of tantalum oxide between the metal interconnections, even if the first diffusion barrier layer at the bottom of the via hole in the misaligned region with the metal interconnection is damaged, diffusion of the metal interconnection material can be completely prevented.

In addition, since the etch stop film that may act as noise in the image sensor including the metal wiring is not required, the noise of the image sensor can be removed.

Therefore, the noise of the image sensor including the metal wiring is removed, and at the same time, the diffusion of the material forming the metal wiring is prevented.

Claims (14)

An interlayer insulating film formed on the substrate and having a trench formed therein; A first diffusion barrier formed along the inner surface of the trench; A metal wiring formed to fill the trench; And A second diffusion barrier layer interposed between the metal wiring and the first diffusion barrier layer Image sensor comprising a. The method of claim 1, The second diffusion barrier layer is formed on the inner wall of the first diffusion barrier layer, respectively. The method according to claim 1 or 2, The first diffusion barrier layer is formed of any one of Ta, TaN single layer and Ta / TaN laminated film. The method of claim 3, wherein The second diffusion barrier layer is formed of tantalum oxide. The method of claim 4, wherein The second diffusion barrier is an image sensor formed to a thickness of 1 ~ 100nm. The method of claim 4, wherein The image sensor further comprises a metal capping layer formed on the metal wiring. Etching a portion of the interlayer insulating film deposited on the substrate to form a trench; Depositing a first diffusion barrier along a step of an upper portion of the interlayer insulating layer including the trench; Forming a second diffusion barrier on the surface of the first diffusion barrier; Removing the second diffusion barrier layer formed on the bottom of the trench such that the second diffusion barrier layer remains only on an inner sidewall of the first diffusion barrier layer; Depositing a metal wiring in which the trench is embedded; And Planarizing the metal wiring so that a step with the interlayer insulating film is removed; Image sensor manufacturing method comprising a. The method of claim 7, wherein And forming the second diffusion barrier layer using an oxygen plasma process. The method of claim 8, The oxygen plasma process is performed for 10-30 seconds in an O ₂ plasma at a temperature of 100 ~ 600 ℃. The method according to claim 7 or 8, The first diffusion barrier layer is formed of any one of Ta, TaN single layer and Ta / TaN laminated film. The method of claim 10, The second diffusion barrier layer is formed of tantalum oxide. The method of claim 11, The tantalum oxide is an image sensor manufacturing method to form a thickness of 1 ~ 100nm. The method of claim 11, Removing the second diffusion barrier layer formed on the bottom of the trench using a physical sputtering process. The method of claim 11, And forming a metal capping layer on the metal wiring.

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