JPH0831932A - Manufacture of semiconductor integrated circuit device - Google Patents

Abstract

PURPOSE:To prevent short circuit and discontinuity of an interconnection due to the collapse of the selectivity of a tungsten plug technique and to enhance the yield of a product in a semiconductor integrated circuit device which is provided with a tungsten plug in an interconnection structure. CONSTITUTION:A silicon oxide film 10 and an aluminum oxide film 12 are formed on a semiconductor substrate 1. They are etched sequentially by using a resist mask, and a contact hole 14 is formed. Then, a tungsten film 15 is buried inside the contact hole 14 by a monosilane-reduction CVD method of tungsten hexa-fluoride gas or a hydrogen-reduction CVD method. At this time, a tungsten nucleus 16 is grown also on the surface of the aluminum oxide film 12. Then, the aluminum oxide film 12 is removed by a hot phosphoric acid solution, the tungsten nucleus 16 is lifted off, and a tungsten plug is formed inside the contact hole 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor integrated circuit device, and more particularly, to forming a tungsten plug in a contact hole for connecting a semiconductor element to a wiring layer and connecting upper and lower wiring layers. The present invention relates to a technique effectively applied to a semiconductor integrated circuit device.

[0002]

2. Description of the Related Art ULS is used for forming highly reliable fine wiring.
This is an important technology for realizing I (Ultra-Large-Scale Integrated Circuits).

However, as the degree of integration of the semiconductor integrated circuit device increases, the horizontal direction of the chip is miniaturized, whereas the vertical direction is not scaled, so that the aspect ratio of the contact hole becomes large and the fine contact hole is fine. It is difficult to uniformly form the wiring to the bottom of the. Therefore, there is a problem that the contact resistance of the wiring increases and the wiring is broken due to electromigration or stress migration.

Therefore, at present, selective CVD (Chemical V
By the apor deposition method, a tungsten plug technique has been studied in which a tungsten film is selectively grown only on a semiconductor substrate exposed at the bottom of a contact hole and the inside of the contact hole is completely filled with the tungsten film.

Proceedings of 38th Seminar on Semiconductor Seminar "Fine wiring forming technology using tungsten CVD", 1992,
P185 describes a method of forming a tungsten plug by the selective CVD method.

For example, in a DRAM which is one of semiconductor integrated circuit devices, first, a MISFET in a memory cell portion and a peripheral circuit portion and an information storage capacitor element in the memory cell portion are formed, and then a silicon oxide film is deposited. An interlayer insulating film is formed. Next, using the resist formed on the interlayer insulating film as a mask, the interlayer insulating film is processed by dry etching to form a contact hole.

Next, after pre-cleaning by plasma cleaning, a CVD method using tungsten hexafluoride (WF ₆ ) gas and monosilane (SiH ₄ ) gas is used to select from the surface of the semiconductor substrate at the bottom of the contact hole. Then, a tungsten film is grown to fill the contact hole with the tungsten film. At this time, the tungsten film is not formed on the interlayer insulating film formed of the silicon oxide film.

Next, an aluminum alloy film is deposited by a sputtering method and processed to form a wiring layer.

[0009]

However, since the above-mentioned interlayer insulating film is deposited by the CVD method and contact holes are formed in the interlayer insulating film through the photoresist process and the dry etching process, metal contamination, moisture The surface of the interlayer insulating film is unstable due to adsorption of OH groups and the like, and formation of silicon dangling bonds.

Due to the unstable surface condition of the interlayer insulating film, the above-mentioned method for forming the tungsten plug cannot secure the selectivity of the tungsten film, and not only the tungsten film is buried in the contact hole but also the interlayer insulating film is formed. Tungsten nuclei grow on the surface of the film (the selectivity is lost), and the tungsten nuclei are one of the causes of the short circuit and the disconnection of the wiring.

An object of the present invention is to provide a technique capable of preventing a short circuit or a disconnection of a wiring due to the deterioration of the selectivity of the tungsten plug technique and improving the yield of products.

Another object of the present invention is to provide a technique capable of forming a tungsten plug having no tungsten nucleus generated due to the loss of selectivity without increasing the number of manufacturing steps.

Another object of the present invention is to provide a technique capable of widening the process window of a tungsten plug.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0015]

Of the inventions disclosed in the present application, a representative one will be briefly described below.
It is as follows. That is, (1) In the method for manufacturing a semiconductor integrated circuit device according to the present invention, first, after forming an interlayer insulating film, the interlayer insulating film and a tungsten film to be formed later can be selectively removed without being removed. Form a possible metal oxide film. Then, the metal oxide film and the interlayer insulating film are sequentially etched using the resist as a mask to form a contact hole. Then, the contact hole is selectively filled with a tungsten film by a silicon reduction CVD method of tungsten hexafluoride gas or a hydrogen reduction CVD method of tungsten hexafluoride gas, and then the metal oxide film is removed to remove the metal in the contact hole. A tungsten plug is formed on.

(2) In the method of manufacturing a semiconductor integrated circuit device of the present invention, after the interlayer insulating film and the tungsten oxide film are sequentially deposited, the tungsten oxide film and the interlayer insulating film are sequentially etched using the resist as a mask. , Forming contact holes. Next, by a hydrogen reduction CVD method of tungsten hexafluoride gas, the contact hole is selectively filled with a tungsten film, and at the same time, the tungsten oxide film is vaporized and removed by the tungsten hexafluoride gas to remove tungsten in the contact hole. It forms a plug.

(3) In the method for manufacturing a semiconductor integrated circuit device of the present invention, after the interlayer insulating film, the titanium nitride film and the tungsten oxide film are sequentially deposited, the resist is used as a mask to form the tungsten oxide film and the titanium nitride film. Then, the interlayer insulating film is sequentially etched to form a contact hole. Next, hydrogen reduction CVD of tungsten hexafluoride gas
Method, the contact hole is selectively filled with a tungsten film, and at the same time, the tungsten oxide film is vaporized and removed by a tungsten hexafluoride gas to form a tungsten plug in the contact hole. Next, after the tungsten oxide film is completely removed, the tungsten film is continuously deposited on the titanium nitride film to form a wiring layer of the tungsten film.

[0018]

According to the above-mentioned means (1), since all the nuclei of tungsten grown due to the collapse of the selectivity are removed when the metal oxide film is removed, there is no tungsten nuclei on the interlayer insulating film. A plug can be formed.

According to the above-mentioned means (2), the contact hole can be selectively filled with the tungsten film, and at the same time, the nuclei of tungsten grown due to the loss of selectivity can be removed. A tungsten plug having no tungsten nucleus can be formed on the interlayer insulating film without increasing the number of steps.

Further, according to the above-mentioned means (3), the contact hole is selectively filled with the tungsten film and, at the same time, the nuclei of tungsten grown by the collapse of the selectivity are removed, and then the wiring layer is continuously formed. Since the tungsten film to be deposited can be deposited on the interlayer insulating film, the tungsten plug and the wiring layer having no tungsten nucleus can be formed on the interlayer insulating film without increasing the number of manufacturing steps as compared with the conventional technique.

Further, according to the above-mentioned means, since the nuclei of tungsten grown by the collapse of the selectivity can be removed, the process window of the tungsten plug narrowly limited to prevent the growth of the nuclei of tungsten is widened.

[0022]

Embodiments of the present invention will now be described in detail with reference to the drawings.

In all the drawings for explaining the embodiments, those having the same function are designated by the same reference numerals, and the repeated description thereof will be omitted.

(Embodiment 1) DR which is an embodiment of the present invention
A method for manufacturing the AM will be described with reference to FIGS.

First, as shown in FIG. 1, an n-type well 2, a p-type well 3, a field insulating film 4 and a gate insulating film 5 are sequentially formed on the main surface of the semiconductor substrate 1 by a known method, and then the semiconductor substrate is formed. A polycrystalline silicon film and a silicon oxide film 6 are sequentially deposited on 1 by a CVD method.

Next, the polycrystalline silicon film and the silicon oxide film 6 are etched to form the gate electrode 7 of the MISFET, and then the silicon oxide film 6 and the gate electrode 7 are formed.
Is used as a mask to form an n-type impurity or p on the semiconductor substrate 1.
A type impurity is ion-implanted to form the n-type semiconductor region 8 of the n-channel MISFET or the p-type semiconductor region of the p-channel MISFET. Ion implantation of the n-type impurity and the p-type impurity is separately performed using a resist as a mask to form the n-type semiconductor region 8 or the p-type semiconductor region, respectively.

After that, the silicon oxide film deposited by the CVD method on the semiconductor substrate 1 is subjected to RIE (Reactive Ion Etching).
Etching is performed to form a sidewall spacer 9 on the sidewall of the gate electrode 7.

Next, after forming an information storage capacitive element (not shown) in the memory cell portion on the memory cell selection MISFET, a silicon oxide film 10 and an aluminum film 11 are sequentially deposited on the semiconductor substrate 1. Next, the aluminum film 1
1 is oxidized in an ozone atmosphere at a temperature of about 250 ° C. to change all of the aluminum film 11 into an aluminum oxide film 12. At this time, only part of the aluminum film 11 may be changed to the aluminum oxide film 12.

Next, as shown in FIG. 2, after applying a resist on the semiconductor substrate 1 and patterning it, the aluminum oxide film 12 is formed by using the resist mask 13 formed.
Then, the silicon oxide film 10 is sequentially etched to form a contact hole 14 reaching the gate electrode 7 and the n-type semiconductor region 8.

Next, as shown in FIG. 3, after removing the resist mask 13, pre-cleaning is performed, and subsequently, CVD of reducing tungsten hexafluoride gas with monosilane gas is performed.
Method or a CVD method of reducing tungsten hexafluoride gas with hydrogen gas, the tungsten film 1 is formed from the surface of the semiconductor substrate 1 at the bottom of the contact hole 14 and the gate electrode 7.
Grow 5 At this time, the selectivity collapses and the tungsten nuclei 16 grow on the surface of the aluminum oxide film 12.

Next, as shown in FIG. 4, the aluminum oxide film 12 is removed with a hot phosphoric acid solution to grow on the surface of the aluminum oxide film 12 without removing the tungsten film 15 and the silicon oxide film 10. Lifted off the nuclei 16 of the formed tungsten, and contact holes 14
The tungsten film 15 can be left only inside.

Next, a metal film 17 (aluminum alloy film or tungsten film) for forming a wiring layer is deposited on the semiconductor substrate 1, a resist mask is formed, and then the metal film 17 is processed by dry etching. A wiring layer is formed. After removing the resist mask, as shown in FIG.
The DRAM of this embodiment is completed by covering the surface of the semiconductor substrate 1 with the passivation film 18.

(Embodiment 2) A method of manufacturing a DRAM using a tungsten plug which is an embodiment of the present invention will be described with reference to FIG.

First, similar to the manufacturing method described in the first embodiment, the MI of the memory cell portion and the peripheral circuit portion is formed on the semiconductor substrate 1.
The SFET and the information storage capacitive element of the memory cell portion are sequentially formed.

Next, the silicon oxide film 1 is formed on the semiconductor substrate 1.
0, a silicon nitride film 19 and a tantalum oxide film 20 are sequentially deposited. The tantalum oxide film 20 may be deposited by the sputtering method, or the tantalum oxide film 2 is formed by oxidizing the tantalum film deposited by the CVD method or the sputtering method.
0 may be formed.

Next, after applying a resist on the semiconductor substrate 1 and patterning it, the tantalum oxide film 20 and the silicon nitride film 19 are formed using the formed resist mask.
Then, the silicon oxide film 10 is sequentially etched to form a contact hole 14 reaching the gate electrode 7 and the n-type semiconductor region 8.

Next, after removing the resist mask, pre-cleaning is performed, and then contact is made by a CVD method of reducing the tungsten hexafluoride gas with monosilane gas or a CVD method of reducing the tungsten hexafluoride gas with hydrogen or gas. A tungsten film 15 is grown from the surface of the semiconductor substrate 1 and the gate electrode 7 at the bottom of the hole 14. At this time, the selectivity collapses, and the tungsten nuclei 16 grow on the surface of the tantalum oxide film 20.

Next, although not shown, by removing the tantalum oxide film 20 with a hydrofluoric acid solution, the tungsten nuclei 16 grown on the surface of the tantalum oxide film 20 are lifted off, and only the contact holes 14 are covered with tungsten. The membrane 15 can be left behind. The silicon nitride film 19 may be removed or may be used as a part of the interlayer insulating film without being removed.

As described above, when removing the tantalum oxide film 20, even if a solution or gas for etching the silicon oxide film 10 has to be used, the silicon nitride film 19 which is not etched is formed on the surface of the silicon oxide film 10. Since it is formed, the tungsten nucleus 16 can be lifted off without etching the silicon oxide film 10.

Next, similar to the first embodiment, the semiconductor substrate 1
A metal film 17 (aluminum alloy film or tungsten film) for forming a wiring layer is deposited thereon, a resist mask is formed, and then the metal film 17 is processed by dry etching to form a wiring layer. After removing the resist mask,
The DRAM of this embodiment is completed by covering the surface of the semiconductor substrate 1 with the passivation film 18.

(Embodiment 3) A method of manufacturing a DRAM using a tungsten plug according to an embodiment of the present invention will be described with reference to FIG.

First, similarly to the manufacturing method described in the first embodiment, the MI of the memory cell portion and the peripheral circuit portion is formed on the semiconductor substrate 1.
The SFET and the information storage capacitive element of the memory cell portion are sequentially formed.

Next, the silicon oxide film 1 is formed on the semiconductor substrate 1.
0 and the tungsten oxide film 21 are sequentially deposited. The tungsten oxide film 21 may be deposited by a sputtering method, or may be formed by oxidizing a tungsten film deposited by a CVD method or a sputtering method.

Next, after applying a resist on the semiconductor substrate 1 and patterning the resist, the tungsten oxide film 21 and the silicon oxide film 10 are sequentially etched using the formed resist mask to form the contact hole 1
4 is formed.

Next, after removing the resist mask, a tungsten film 15 is grown from the surfaces of the semiconductor substrate 1 and the gate electrode 7 at the bottom of the contact hole 14 by the CVD method of reducing the tungsten hexafluoride gas with hydrogen gas. . At this time, the selectivity collapses, and the tungsten nuclei 16 grow on the surface of the tungsten oxide film 21.

However, since the tungsten oxide film 21 reacts with the tungsten hexafluoride gas to become tungsten fluorinated oxide and is vaporized and removed, the tungsten nuclei grown on the surface of the tungsten oxide film 21 are lifted off. As a result, the tungsten film 15 can be left only in the contact hole 14.

Next, similar to the first embodiment, the semiconductor substrate 1
After depositing a metal film 17 (aluminum alloy film or a tungsten film) for forming a wiring layer thereon and forming a resist mask, the metal film 17 is processed by dry etching. After removing the resist mask, the surface of the semiconductor substrate 1 is covered with the passivation film 18 to complete the DRAM of this embodiment.

(Embodiment 4) A method of manufacturing a DRAM using a tungsten plug according to an embodiment of the present invention will be described with reference to FIGS.

First, as shown in FIG. 8, similarly to the manufacturing method described in the first embodiment, MISFETs in the memory cell portion and the peripheral circuit portion and the information storage capacitor element in the memory cell portion are sequentially formed on the semiconductor substrate 1. To do.

Next, the silicon oxide film 1 is formed on the semiconductor substrate 1.
0, a titanium nitride film 22 and a tungsten oxide film 21 are sequentially deposited. The tungsten oxide film 21 may be deposited by a sputtering method, or may be formed by oxidizing a tungsten film deposited by a CVD method or a sputtering method.

Next, after applying a resist on the semiconductor substrate 1 and patterning it, the tungsten oxide film 21, the titanium nitride film 22 and the silicon oxide film 10 are sequentially etched using the formed resist mask to make contact. The hole 14 is formed.

Next, after removing the resist mask, a tungsten film 15 is grown from the surfaces of the semiconductor substrate 1 and the gate electrode 7 at the bottom of the contact hole 14 by the CVD method of reducing the tungsten hexafluoride gas with hydrogen gas. . At this time, the selectivity collapses, and the tungsten nuclei 16 grow on the surface of the tungsten oxide film 21.

However, since the tungsten oxide film 21 reacts with the tungsten hexafluoride gas and becomes tungsten fluorinated oxide, which is vaporized and removed, the tungsten nuclei 16 grown on the surface of the tungsten oxide film 21 are lifted off. .

Next, as shown in FIG. 9, even after the tungsten oxide film 21 is completely removed, the tungsten film 23 used as the wiring layer is continuously formed by the CVD method of reducing the tungsten hexafluoride gas with hydrogen gas. Titanium nitride film 22
Deposit on the surface of. In the hydrogen reduction CVD method, the tungsten film 23 is hard to be deposited on the surface of the silicon oxide film 10, but it can be deposited on the surface of the titanium nitride film 22, so that the titanium nitride film 22 serves as an adhesive layer and the tungsten film 23 serves as the semiconductor substrate. Can be deposited over the entire surface.

Next, after forming a resist mask, the tungsten film 23 is processed by dry etching to form a wiring layer. After removing the resist, the surface of the semiconductor substrate 1 is covered with a passivation film to complete the DRAM of this embodiment.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the embodiments and various modifications can be made without departing from the scope of the invention. Needless to say.

For example, although the aluminum oxide film is used as the film for lifting off the nuclei of tungsten in the first embodiment, a metal oxide film such as a tungsten oxide film, a titanium oxide film, a molybdenum oxide film or a copper oxide film, or a metal oxide film of these metals is used. The same effect can be obtained by using a laminated metal oxide film composed of a combination of films.

Although the aluminum oxide film is used as the film for lifting off the nuclei of tungsten in the first embodiment,
The same effect can be obtained by using a metal film such as a molybdenum film or a silicon nitride film.

In the fourth embodiment, the titanium nitride film is used as the adhesive layer when forming the tungsten film to be the wiring layer, but the same effect can be obtained by using the aluminum film or the tungsten silicide film.

In the above embodiment, the method of manufacturing the semiconductor integrated circuit device having the tungsten plug formed in the contact hole for connecting the semiconductor substrate and the wiring layer or the gate electrode and the wiring layer has been described. The method is also applicable to a method of manufacturing a semiconductor integrated circuit device having a tungsten plug formed in a contact hole connecting a lower wiring layer made of a metal film (aluminum alloy film or a tungsten film) and an upper wiring layer.

Further, in the above embodiment, the method of manufacturing the DRAM has been described, but the MOS having the tungsten plug is used.
It is also applicable to LSI and bipolar LSI.

[0062]

The effects obtained by the typical ones of the inventions disclosed in this application will be briefly described as follows.
It is as follows.

According to the present invention, since all the nuclei of tungsten grown due to the collapse of the selectivity can be removed, it is possible to form a tungsten plug without a nucleus of tungsten on the interlayer insulating film, and the selectivity of the tungsten plug technology is deteriorated. The resulting wiring short circuit and disconnection are prevented, and the product yield is improved.

Further, according to the present invention, since the formation of the tungsten plug and the removal of the nuclei of the grown tungsten due to the collapse of the selectivity can be performed at the same time, the selectivity is destroyed without increasing the manufacturing process as compared with the prior art. It is possible to form a tungsten plug having no tungsten nucleus generated by the above.

Further, according to the present invention, since the formation of the tungsten plug and the removal of the nuclei of the tungsten grown due to the collapse of the selectivity are simultaneously performed, the wiring layer can be continuously formed, so that the manufacturing method as compared with the prior art is improved. It is possible to form a tungsten plug and a wiring layer having no tungsten nucleus generated due to the loss of selectivity without increasing the number of steps.

Further, according to the present invention, since the nuclei of tungsten that have grown due to the loss of selectivity can be removed, the conditions for forming the tungsten plug, which is narrowly limited to prevent the growth of tungsten nuclei, become wider.

[Brief description of drawings]

FIG. 1 is a fragmentary cross-sectional view of a semiconductor substrate showing a manufacturing process of a DRAM which is an embodiment of the present invention.

FIG. 2 is a cross-sectional view of essential parts of a semiconductor substrate showing a manufacturing process of a DRAM which is an embodiment of the present invention.

FIG. 3 is a fragmentary cross-sectional view of a semiconductor substrate showing a manufacturing process of a DRAM which is an embodiment of the present invention.

FIG. 4 is a cross-sectional view of essential parts of a semiconductor substrate showing a manufacturing process of a DRAM which is an embodiment of the present invention.

FIG. 5 is a fragmentary cross-sectional view of a semiconductor substrate showing a manufacturing process of a DRAM which is an embodiment of the present invention.

FIG. 6 is a fragmentary cross-sectional view of a semiconductor substrate showing a manufacturing process of a DRAM which is another embodiment of the present invention.

FIG. 7 is a fragmentary cross-sectional view of a semiconductor substrate showing a manufacturing process of a DRAM which is another embodiment of the present invention.

FIG. 8 is a fragmentary cross-sectional view of a semiconductor substrate showing a manufacturing process of a DRAM which is another embodiment of the present invention.

FIG. 9 is a fragmentary cross-sectional view of a semiconductor substrate showing a manufacturing process of a DRAM which is another embodiment of the present invention.

[Explanation of symbols]

 1 semiconductor substrate 2 n-type well 3 p-type well 4 field insulating film 5 gate insulating film 6 silicon oxide film 7 gate electrode 8 n-type semiconductor region 9 sidewall spacer 10 silicon oxide film 11 aluminum film 12 aluminum oxide film 13 resist mask 14 Contact hole 15 Tungsten film 16 Tungsten nucleus 17 Metal film 18 Passivation film 19 Silicon nitride film 20 Tantalum oxide film 21 Tungsten oxide film 22 Titanium nitride film 23 Tungsten film

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01L 21/3205

Claims (6)

[Claims] 1. A method of manufacturing a semiconductor integrated circuit device, wherein a tungsten plug is formed in a contact hole connecting a semiconductor element and a wiring layer or between upper and lower wiring layers, wherein a metal oxide film is formed on an interlayer insulating film. A step of forming a contact hole by etching the metal oxide film and the interlayer insulating film, a step of selectively burying a tungsten film in the contact hole by a CVD method,
A method of manufacturing a semiconductor integrated circuit device, comprising the step of selectively removing the metal oxide film. 2. The semiconductor integrated circuit device according to claim 1, wherein the metal oxide film is an aluminum oxide film, a tantalum oxide film, a tungsten oxide film, a titanium oxide film, a molybdenum oxide film, or a copper oxide film. Manufacturing method. 3. The method of manufacturing a semiconductor integrated circuit device according to claim 1, wherein the CVD method is a silicon reduction CVD method of tungsten hexafluoride gas or a hydrogen reduction CVD method of tungsten hexafluoride gas. . 4. A method of manufacturing a semiconductor integrated circuit device, comprising forming a tungsten plug in a contact hole connecting a semiconductor element and a wiring layer, the method comprising forming a tungsten oxide film on an interlayer insulating film, A step of etching the tungsten film and the interlayer insulating film to form a contact hole, and selectively burying the tungsten film in the contact hole and removing the tungsten oxide film by a hydrogen reduction CVD method of tungsten hexafluoride gas A method of manufacturing a semiconductor integrated circuit device, comprising: 5. A method of manufacturing a semiconductor integrated circuit device, wherein a tungsten plug is formed in a contact hole connecting a semiconductor element and a wiring layer, the step of forming an adhesive layer and a tungsten oxide film on an interlayer insulating film. A step of etching the tungsten oxide film, the adhesive layer, and the interlayer insulating film to form a contact hole, and selectively burying the tungsten film in the contact hole by a hydrogen reduction CVD method of tungsten hexafluoride gas. A method for manufacturing a semiconductor integrated circuit device, comprising the steps of: after removing the tungsten oxide film, successively depositing a tungsten film on the adhesive layer by a hydrogen reduction CVD method of tungsten hexafluoride gas. . 6. The method of manufacturing a semiconductor integrated circuit device according to claim 5, wherein the adhesive layer is a titanium nitride film, an aluminum film or a tungsten silicide film.