KR20050107027A - Method for forming contact hole and conductive structure using the same - Google Patents

Abstract

A method for forming a contact hole and a conductive structure having excellent aspect ratio is disclosed. The contact hole may form an insulating film and a metal film on a substrate including a conductive pattern, and form a photoresist pattern having a first opening defining an exposed area of the conductive pattern on the metal film. Subsequently, the metal film exposed to the photoresist pattern is first etched such that the metal polymer is adsorbed onto the photoresist pattern to form an etch mask having a second opening smaller than the first opening. Subsequently, the insulating layer exposed to the etching mask is formed by second etching. As such, the contact hole formed by using the etching mask having the high etching selectivity due to the adsorption of the metallic polymer has a high aspect ratio, does not damage the inlet, and has a vertical profile.

Description

Contact hole formation method and conductive structure formation method using the same {METHOD FOR FORMING CONTACT HOLE AND CONDUCTIVE STRUCTURE USING THE SAME}

The present invention relates to a method of forming a contact hole of a semiconductor device and a method of forming a conductive structure using the same. More particularly, a method of forming a contact hole having a very deep and small open size by applying a mask pattern having an excellent etching selectivity and a conductive structure using the same It relates to a method of forming.

In recent years, in an information society that is growing rapidly, semiconductor devices have been highly integrated in order to process large amounts of information faster with the development of various technologies.

As the semiconductor device, a DRAM device having free input and output of information and having a high capacity is widely used. In the DRAM device, each memory cell includes one access transistor and one storage capacitor.

As the degree of integration of the memory cell is required, reduction of design rules for forming capacitors having a three-dimensional shape in a reduced area and forming a multilayer and a capacitor having a high storage capacity is becoming more important. .

As described above, a contact is required to electrically connect the interlayer interconnections by forming a plurality of wires, and a deep contact hole is formed in the insulating layer to maximize the height of the storage node electrode in order to increase the capacitance of the capacitor. How to do it.

As the deep contact hole is required as described above, various limitations are revealed in the process of forming the contact hole using only the photoresist pattern alone. In particular, the ArF photoresist pattern forming process introduced as small patterns of less than 100 nm are required to have a higher photo-resistance rate in dry etching process because it has characteristics such as resistance to dry etching, thickness reduction of photoresist, and use of an organic anti-reflection film. Requires an etching selectivity of the resist.

In order to have a high etching selectivity of the photoresist pattern, a method of adsorbing a fluorocarbon polymer to the photoresist pattern is commonly used. However, the fluorocarbon polymer reacts with oxygen during the dry etching process, and a reaction such as CxFy + O ₂ → CO ₂ + CO + COFx occurs. That is, the fluorocarbon polymer may be easily removed during the dry etching process for reacting with oxygen ions or oxygen radicals to form a deep contact hole. Therefore, a problem arises in that the critical dimension of the photoresist pattern is increased or deformed during the dry etching process for forming the deep contact hole, so that the critical dimension of the contact hole formed by the method is uneven.

Accordingly, an object of the present invention for solving the above problems is to provide a method for forming a contact hole having a uniform critical dimension of an open area and a high aspect ratio.

In addition, another object of the present invention to provide a method for forming a conductive structure using the above-described contact hole forming method.

Contact hole forming method of the present invention for achieving the above object,

Forming an insulating film on a substrate including a conductive pattern; Forming a metal film on the insulating film; Forming a photoresist pattern on the metal layer, the photoresist pattern having a first opening defining a contact region of the conductive pattern; First etching the exposed metal layer while allowing the metallic polymer to be adsorbed onto the surface of the photoresist pattern, thereby forming an etching mask having a second opening having a smaller opening than the first opening; And etching the insulating film exposed to the etching mask having the second opening by adsorbing the metallic polymer to form a contact hole exposing the conductive pattern.

The conductive structure forming method of the present invention for achieving the above-mentioned other object,

Forming an insulating film on a substrate including a conductive pattern; Forming a metal film on the insulating film; Forming a photoresist pattern on the metal layer, the photoresist pattern having a first opening defining a contact region of the conductive pattern; First etching the exposed metal layer while allowing the metallic polymer to be adsorbed onto the surface of the photoresist pattern, thereby forming an etching mask having a second opening having a smaller opening than the first opening; Forming a contact hole exposing the conductive pattern by second etching the insulating film exposed to the etching mask having the second opening by adsorbing the metallic polymer; And embedding a conductive material in the contact hole to form a conductive structure.

Conductive structure forming method of the present invention according to an embodiment for achieving the above-mentioned other object,

Forming an insulating film on a substrate including a conductive pattern; Forming a metal film on the insulating film; Forming a photoresist pattern on the metal layer, the photoresist pattern having a first opening defining a contact region of the conductive pattern; First etching the exposed metal layer while allowing the metallic polymer to be adsorbed onto the surface of the photoresist pattern, thereby forming an etching mask having a second opening having a smaller opening than the first opening; Forming a contact hole exposing the conductive pattern by second etching the insulating film exposed to the etching mask having the second opening by adsorbing the metallic polymer; Removing the etching mask; And forming a lower electrode of the capacitor electrically connected to the conductive pattern in the contact hole.

As such, the metal-halogen polymer has an excellent etching selectivity with respect to the insulating film. Therefore, by using the photoresist pattern to which the metal-halogen polymer is adsorbed as an etching mask, contact holes and contact plugs having a high aspect ratio can be formed.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Example 1

1 to 4 are cross-sectional views illustrating a method for forming a contact hole in a semiconductor device according to a first embodiment of the present invention.

Referring to FIG. 1, after forming gate electrodes (not shown) including a gate spacer of a semiconductor substrate 100, a source / drain 120 is formed by implanting impurities by applying a gate electrode as an ion implantation mask. . Although not shown in the drawing, a metal silicide film (not shown) that is an ohmic contact layer is formed in the source / drain region.

 Subsequently, an interlayer insulating layer covering the gate electrode is deposited, and then an interlayer insulating layer 130 is formed by performing a chemical mechanical polishing (CMP) process, that is, a planarization process. A metal film 132 is formed on the interlayer insulating film.

The metal layer 132 is a material that can then be dry etched and adsorbed into the opening of the photoresist pattern after forming a photoresist pattern having a first opening defining an exposed region of the source / drain 120.

That is, the metal film may be, for example, a metal film such as Ti, TiN, Al, W, TiAlN, TiSix, WSix, Co, CoSix, Cr, Ni, Cu, and the like, and in Example 1, an aluminum film is preferably formed. .

Referring to FIG. 2, an anti-reflection film 134 and a photoresist pattern 136 are formed on the aluminum film 132. The antireflection film 134 is preferably an organic antireflection film.

The photoresist pattern 136 is formed by applying a photoresist, and then performing exposure, development, cleaning, and baking processes to expose the aluminum layer 132 on the source / drain 120. It has an opening P1.

Referring to FIG. 3, the aluminium metal layer 132 exposed to the photoresist pattern 136 is dry-etched using the photoresist pattern 136 having the first opening P1 as an etching mask. The dry etching of the aluminum film 132 may be performed using an etching gas containing a Group 7 element. For example, Cl ₂ , HBr, BCl ₃ , SF _6, and NF ₃ gas may be used as the etching gas. Can be.

When the aluminum film 132 is dry-etched using the above-described etching gas, the aluminum film is etched to generate a metal-halogen polymer (AlxCl _y : P), which is a metal polymer, so that the photoresist pattern 136 having the first opening is formed. Is adsorbed on the surface. Due to the adsorption of the metal-halogen polymer (AlxCl _y ; P), the photoresist pattern 136 is formed as an etching mask 136a having a second opening P2 having a smaller exposed area of the metal film than the first opening.

Although not shown in the drawing, the metal-halogen polymer (P) adsorbed on the photoresist pattern 136 subsequently reacts with the etching gas (C _x F _y ) to etch the interlayer insulating film to generate a higher boiling point. It may be modified into a polymer (AlxF _y ; P) having. And, metal-halogen polymers, unlike fluorocarbon polymers, are not easily removed by reaction with ions or radicals in the dry etching process.

For example, aluminum fluorine (AlF ₃ ) is reacted with oxygen (O ₂ ) to form aluminum oxide (Al ₂ O ₃ ) and fluorine aluminum oxide compound (Al _x F _y O _z ). The aluminum oxide thus formed is not easily evaporated during the dry etching process because the boiling point is high at 3000 ° C., so that the aluminum oxide remains in the photoresist pattern to increase the etching selectivity of the photoresist pattern.

Referring to FIG. 4, a source disposed between the gate electrodes 110 may be formed by etching the interlayer insulating layer 130 exposed by the metal halogen polymer P and exposed to the etching mask 136a having the second opening P2. A contact hole 140 is formed to expose the drain 120. Due to the formation of the contact hole 140, the interlayer insulating layer is formed of the interlayer insulating layer pattern 130a.

That is, since the above-described metal-halogen polymer is present on the surface of the photoresist pattern having the first opening p2, when the contact hole having a high aspect ratio is formed in the interlayer insulating layer, the etching selectivity of the photoresist pattern is further improved. You can.

Example 2

5 to 11 are cross-sectional views illustrating a method for forming a contact plug in a semiconductor device according to a second exemplary embodiment of the present invention.

Referring to FIG. 5, an interlayer insulating film 230 is formed on a semiconductor substrate 200 including a conductive pattern 210. Herein, copper, aluminum, tungsten, silver, gold, platinum, or the like may be used as a material constituting the conductive pattern 210, but the conductive pattern 210 of the present invention is preferably a tungsten pattern.

As an insulating material for forming the interlayer insulating film 230, SiO ₂ , SiON, siloxane SOG, silicate SOG, PSG, PEOX, P-TEOS, USG and FSG, HSG materials can be used, but the interlayer insulating film of the second embodiment 230 is an FSG film.

Referring to FIG. 6, a photoresist pattern 236 having a titanium film 232, an antireflection film 234, and a first opening P1 is formed on the interlayer insulating film 230. The photoresist pattern 236 having the first opening exposes the titanium film 232 corresponding to the position where the conductive pattern 210 is formed.

Referring to FIG. 7, the anti-reflection film 234 and the titanium film 232 exposed to the photoresist pattern 236 are dry-etched using the photoresist pattern 236 having the first opening as an etching mask. In the dry etching of the titanium film 232, Cl ₂ , HBr, BCl ₃ , SF _6, and NF ₃ gas, which is an etching gas containing a Group 7 element, may be used, and preferably, NF ₃ gas is used. Do.

When the titanium film 232 is dry-etched using the above-described etching gas, the titanium film 232 is etched to generate metal-halogen polymer (TiF ₃ ; p). The metal-halogen polymer (TiF ₃ ; p) thus generated is adsorbed on the surface of the photoresist pattern 236 having the first openings to etch the second openings p2 having the photoresist pattern 236 smaller than the first openings. It forms with the mask 236a.

In this case, the titanium film 232 is formed of a titanium pattern 232a by the etching process.

When the metal-halogen polymer (TiF ₃ ) remaining on the surface of the photoresist pattern 236 forms a contact hole 240 having a high aspect ratio in the interlayer insulating layer 230, an etching selection of the photoresist pattern 236 is performed. It serves to improve rain. A more detailed description of the metal-halogen polymer (p) will be omitted in order to avoid duplication because it is described in detail in Example 1 above.

Referring to FIG. 8, a contact for exposing the conductive pattern 210 by etching the interlayer insulating layer 230 exposed to the etch mask 236a having the second opening p2 adsorbed by the metal halide polymer p is adsorbed. The hole 240 is formed. Due to the formation of the contact hole 240, the interlayer insulating film 230 is formed of the interlayer insulating film pattern 230a. The contact hole 240 thus formed has a vertical profile and has an excellent aspect ratio.

Referring to FIG. 9, an ashing strip process is performed to remove the photoresist pattern on which the polymer is adsorbed, that is, the etching mask 236a and the antireflection pattern 234a. In this case, in order to more easily remove the etching mask 236a in which the polymer is present, it is preferable to provide fluorine gas during the ashing process. Thereafter, it is preferable to perform a dry cleaning process or a wet cleaning process.

Subsequently, the titanium pattern 232a existing on the interlayer insulating film pattern 230a is removed. The titanium pattern 232a may be removed by performing an etch back process or a chemical mechanical polishing process.

Although not shown in the drawings, the metal pattern may not be removed when the metal wiring is formed after the contact hole forming process.

Referring to FIG. 10, the barrier layer 242 having a uniform thickness is continuously formed on the top surface of the contact hole 240 and the interlayer insulating pattern 230a exposing the conductive pattern 210. Here, the first barrier film 242 serves to prevent the metal material constituting the metal wiring from being diffused into the interlayer insulating film when the metal wire is formed, and the Ti, Ta, W, TiN, TaN, It is formed of a material such as WN, WCN, TiSiN, TaSiN, WSiN or a combination thereof.

In addition, the barrier film may be formed by applying a chemical vapor deposition (CVD), sputter deposition, physical vapor deposition (PVD), ALD, E-beam evaporation, electroless chemical deposition, electrochemical deposition.

11 and 12, a contact hole 240 in which the barrier film 242 is formed is buried, and a metal film 244 covering the top surface of the interlayer insulating film pattern 230a is formed. The metal film 244 may be formed using chemical vapor deposition (CVD), physical vapor deposition (PVD), ALD, E-beam evaporation, electroless chemical deposition, electro chemical deposition, or the like. Subsequently, since the metal film 244 has a non-uniform thickness, a chemical mechanical polishing (CMP) process is performed to expose the top surface of the interlayer insulating pattern 236a to form the metal wiring 244a.

Next, although not shown in the drawings, a passivation film (not shown) may be further formed to protect the metal wiring 244 from various contaminations caused by an external environment, a subsequent process, or the like.

Example 3

12 to 14 are cross-sectional views illustrating a method of forming the lower electrode of the semiconductor device according to the third exemplary embodiment of the present invention.

Since the method for forming the contact hole shown in FIG. 12 is described in detail in the second embodiment, it is omitted to avoid duplication.

As shown in FIG. 13, an ashing strip process is performed to remove the photoresist pattern on which the polymer is adsorbed, that is, the etching mask 336a and the antireflection pattern 334a. In this case, in order to more easily remove the etching mask 336a in which the polymer is present, it is preferable to provide fluorine gas during the ashing process. Thereafter, it is preferable to perform a dry cleaning process or a wet cleaning process.

Subsequently, the contact hole 340 exposing the contact plug 244a and the lower metal layer 342 having a uniform thickness are continuously formed on the upper surface of the titanium pattern 232a. The lower metal layer 342 may be formed by sputter deposition, physical vapor deposition (PVD), ALD, or the like.

As shown in FIG. 14, after the insulator is buried in the contact hole 340 in which the lower metal layer 342 is formed, a chemical mechanical smoke process is performed to expose the top surface of the interlayer insulating pattern 330a. The lower metal pattern 342 existing only in the 340 is formed.

Subsequently, a wet etching process of removing the insulation existing in the interlayer insulating pattern 333a and the contact hole 340 is performed to form the lower electrode 342 of the capacitor electrically connected to the doped pattern.

As described above, according to the present invention, a deep contact hole may be formed in the interlayer insulating layer by using a photoresist pattern adsorbed with a metal-halide polymer as an etching mask.

That is, the photoresist pattern may form a contact hole having an excellent critical dimension and a high aspect ratio because the photoresist pattern does not have a problem of opening or deforming the critical dimension of the photoresist pattern during a dry etching process for forming a deep contact hole. have.

Due to the formation of the contact hole having the above-described structure, it is possible to form the lower electrode of the contact plug and the capacitor, which are electrically connected to the conductive pattern and have an excellent profile. Therefore, the effect that the productivity and reliability of manufacturing a semiconductor device can be improved can be expected.

As described above, although described with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified without departing from the spirit and scope of the invention described in the claims below. And can be changed.

1 to 4 are process cross-sectional views showing a method for forming a contact hole in a semiconductor device according to a first embodiment of the present invention.

5 to 11 are cross-sectional views illustrating a method for forming a contact plug in a semiconductor device according to a second exemplary embodiment of the present invention.

12 to 14 are cross-sectional views illustrating a method of forming the lower electrode of the semiconductor device according to the third exemplary embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

100: substrate 120: source / drain

130: interlayer insulating film 130a: interlayer insulating pattern

132: metal film 134: antireflection film

136: photoresist pattern 136a: etching mask

140: contact hole p: polymer

Claims (19)

(a) forming an insulating film on the substrate including the conductive pattern; (b) forming a metal film on the insulating film; (c) forming a photoresist pattern on the metal film, the photoresist pattern having a first opening defining a contact region of the conductive pattern; (d) first etching the exposed metal film while allowing the metallic polymer to be adsorbed onto the surface of the photoresist pattern, thereby forming an etching mask having a second opening having a smaller opening than the first opening; (e) forming a contact hole exposing the conductive pattern by second etching the insulating film exposed by the etching mask. The method of claim 1, further comprising forming an anti-reflection film after the step (a). The method of claim 2, wherein the anti-reflection film is an organic anti-reflection film. The method of claim 1, wherein the metal film is any one selected from the group consisting of Ti, TiN, Al, W, TiAlN, TiSix, WSix, Co, CoSix, Cr, Ni, and Cu films. The method of claim 4, wherein the metal film is a Ti film or an Al film. The method of claim 1, wherein the first etching is a dry etching process. The method of claim 6, wherein the etching gas applied to the dry etching process comprises at least one selected from the group consisting of Cl ₂ , HBr, BCl ₃ , SF _6, and NF ₃ gas. The method of claim 1, wherein the metallic polymer is a metal-halogen polymer. The method of claim 8, wherein the metal-halogen polymer is a metal-fluorine polymer, a metal-chloride polymer, or a metal-bromide polymer. The method of claim 1, wherein after the step (e), the etching mask to which the metallic polymer is adsorbed is removed by an ashing strip process. The method of claim 10, wherein fluorine gas is provided during the ashing strip process. The method of claim 10, wherein after the ashing strip process, a dry cleaning process or a wet cleaning process is performed. The method of claim 10, wherein after the step (e), the metal film is removed. The method of claim 13, wherein the metal film is removed by performing an etch back process or a chemical mechanical polishing process. (a) forming an insulating film on the substrate including the conductive pattern; (b) forming a metal film on the insulating film; (c) forming a photoresist pattern on the metal film, the photoresist pattern having a first opening defining a contact region of the conductive pattern; (d) dry etching the exposed metal film while allowing the metallic polymer to be adsorbed onto the surface of the photoresist pattern, thereby forming an etching mask having a second opening having a smaller opening than the first opening; (e) forming a contact hole through which the metallic polymer is adsorbed to etch the insulating film exposed to the etching mask having the second opening to expose the conductive pattern; And (f) embedding a conductive material in the contact hole. The method of claim 15, wherein the metal film is any one selected from the group consisting of Ti, TiN, Al, W, TiAlN, TiSix, WSix, Co, CoSix, Cr, Ni, and Cu. The method of claim 15, wherein the etching gas applied to the dry etching comprises at least one selected from the group consisting of Cl ₂ , HBr, BCl ₃ , SF _6, and NF ₃ gas. The method of claim 15, wherein the metallic polymer is a metal-halogen polymer and the metal-halogen polymer is a metal-fluoride polymer, a metal-chloride polymer, or a metal-bromide polymer. (a) forming an insulating film on the substrate including the conductive pattern; (b) forming a metal film on the insulating film; (c) forming a photoresist pattern on the metal film, the photoresist pattern having a first opening defining a contact region of the conductive pattern; (d) first etching the exposed metal film while allowing the metallic polymer to be adsorbed onto the surface of the photoresist pattern, thereby forming an etching mask having a second opening having a smaller opening than the first opening; (e) forming a contact hole exposing the conductive pattern by second etching the insulating film exposed to the etching mask having the second opening by adsorbing the metallic polymer; (f) removing the etching mask; And (g) forming a lower electrode of the capacitor electrically connected to the conductive pattern in the contact hole.