JP3038875B2 - Method for manufacturing semiconductor device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly, to a method of manufacturing a semiconductor device through a connection hole provided in an insulating film on a semiconductor substrate. The present invention relates to a method for manufacturing a wiring layer to be electrically connected.

[Conventional technology]

Conventionally, as a method of manufacturing this type of semiconductor device, there is a method of embedding tungsten by a selective vapor deposition method.

FIG. 3 is a cross-sectional view for explaining this method. An element isolation region 302 formed on the surface of a semiconductor substrate 301 made of silicon, an insulating film 304 is deposited on the conductor region 303, and a connection hole is formed at a desired position of the insulating film 304 by lithography and etching technology. Tungsten 307 is buried in the connection hole by selective vapor deposition.

However, when using the vapor deposition method for such a structure, the source gas WF ₆ reacts with the silicon forming the conductor layer 303 to form the insulating film 304 and the conductor region 303. Tungsten penetrates (enclusions) at the interface, and further penetrates to the interface between the element isolation region 302 and the semiconductor substrate 301, causing a problem that junction leakage and junction destruction occur.

In response to this problem, recently, as shown in FIG.
A crystalline or amorphous silicon film 311 is provided on the side wall of the contact hole to form an insulating film 304 during selective vapor deposition of tungsten 307.
A method of not exposing the interface between the conductor region 303 and the conductor region 303 is disclosed in, for example, JP-A-63-237441. This method will be described below. After providing an element isolation region 302 and a conductor region 303 on the surface of a semiconductor substrate 301 made of silicon, an insulating film 304 is formed. A connection hole reaching the conductor region 303 is provided at a desired position of the insulating film 304. After a silicon film is formed on the entire surface, the silicon film 311 is left only on the side wall of the connection hole by etch back. Thereafter, selective vapor deposition of tungsten is performed, and only the connection holes are filled with tungsten 307.

[Problems to be solved by the invention]

In the case of performing the selective vapor deposition on the connection hole having the silicon film formed on the side wall as described above, as shown in FIG. 5, the growth of the tungsten 307 to be buried is performed not only from the surface of the conductor region 303 but also from the silicon film. It also originates from the surface of 311. Therefore, the cavity 312 is easily generated. When the cavity 312 is generated, the connection hole is not completely filled with the tungsten 307, and in an extreme case, the tungsten 307 may be disconnected. Further, since the side wall of the connection hole is covered with the silicon film 311, the effective area at the bottom of the connection hole is reduced.

As a result, when the wiring layer (not shown) formed on the insulating film 304 is connected to the conductor region 303 through the connection hole, the contact resistance increases, and in extreme cases, the wiring layer The connection between and the conductor region 303 is opened. That is, the value of the contact resistance varies in a higher direction.

[Means for solving the problem]

The method of manufacturing a semiconductor device according to the present invention is a method of forming a wiring layer of a semiconductor device, comprising: forming a conductor region and an element isolation region on a surface of a semiconductor substrate made of silicon; A step of forming an insulating film having a connection hole with the layer, and in a selective vapor deposition of a high melting point metal, a conductive material that is less likely to be a nucleation site than the semiconductor substrate surface,
A step of surrounding the side wall of the connection hole; a step of diffusing impurities into the surface of the semiconductor substrate exposed by the connection hole; and a step of selectively vapor-depositing a high-melting metal to fill the inside of the connection hole with the high-melting metal. And forming an upper wiring layer connected to the conductor region through the connection hole on the insulating film.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

1 (a) to 1 (d) are sectional views in the order of steps for explaining a first embodiment of the present invention.

First, as shown in FIG. 1A, an element isolation region 102 and a conductor region 10 are formed on a semiconductor substrate 101 made of silicon.
After forming 3, an insulating film 1 serving as an interlayer film is formed by a vapor growth method.
04 is formed to a thickness of about 1 μm, and a connection hole 105 reaching the conductor region 103 is formed by lithography technology.

Next, as shown in FIG. 1B, titanium nitride 106 of about 150 nm is deposited on the entire surface by a reactive sputtering method.

Next, as shown in FIG. 1C, the titanium nitride 106 deposited on the insulating film 104 and the conductor region 103 is removed by anisotropic etching. By this etching, the connection hole 105
The titanium nitride 106a remains only on the side wall of the substrate. Subsequently, ions of P (phosphorus) or BF ₂ are implanted according to the conductivity type of the conductor region 103, and heat treatment is performed in a nitrogen atmosphere at about 850 ° C. This ion implantation is performed in consideration of the case where connection hole 105 is displaced from conductor region 103.

Next, as shown in FIG. 1 (d), tungsten 107 is selectively buried in the connection hole 105 by the SiH ₄ reduction method of WF ₆ gas. Subsequently, an aluminum wiring layer (not shown) connected to the conductor region 103 through the tungsten 107 in the connection hole 105 is formed on the insulating film 1 by sputtering and lithography.
Formed on 04.

In this embodiment, the nucleation site in the vapor phase growth of tungsten is a conductor region as compared with titanium nitride 106a.
The silicon constituting 103 is overwhelmingly large. Therefore, the growth of the tungsten 107 from the side wall of the connection hole 105 is unlikely to occur, and the generation of a cavity in the grown tungsten 107 is suppressed. Further, the insulating film 104 and the conductor region 103
Interface is separated by titanium nitride 106a,
Penetration (encroachment) of the tungsten 107 into the interface is eliminated, and junction leakage can be reduced. Furthermore, since the side wall of the connection hole 105 is surrounded by the titanium nitride 106a, which is a conductive material, the effective diameter of the connection hole 105 does not decrease, and the factor that increases the contact resistance is eliminated.

2 (a) to 2 (e) are sectional views in the order of steps for explaining a second embodiment of the present invention.

First, as shown in FIG. 2A, an element isolation region 202 and a conductor region 20 are formed on a semiconductor substrate 201 made of silicon.
After forming 3, an insulating film 2 to be an interlayer film by a vapor growth method.
04 is formed, and the conductor region 203 is formed by lithography technology.
Is formed.

Next, as shown in FIG. 2B, a titanium 208 of, for example, about 200 nm is deposited by a sputtering method.

Next, as shown in FIG. 2C, the titanium 208 deposited on the insulating film 204 and the conductor region 203 is removed by anisotropic etching. Due to this etching, titanium 208a remains only on the side wall of connection hole 205. Subsequently, the P, or ion implantation BF ₂ or the like according to the conductivity type of the conductor region 203.

Next, as shown in FIG. 2D, lamp annealing is performed in an ammonia atmosphere at about 700 ° C. By this treatment, titanium nitride 206a is formed on the surface of titanium 208a, and titanium silicide 209 is formed on the interface between titanium 208a and conductive region 203. At the same time, the impurities by the above-described ion implantation are activated.

Next, as shown in FIG. 2 (e), molybdenum 210 is embedded in the connection hole 205 by the H ₂ reduction method of MoF ₆ . Subsequently, the connection hole 20 is formed by sputtering and lithography.
An aluminum wiring layer (not shown) connected to the conductor region 203 via the molybdenum 210 in 5 is formed on the insulating film 204.

In the present embodiment, other than the surface of the film covering the side wall of the connection hole 205 is formed of titanium 208a, and since titanium silicide 209 is formed at a portion where the film and the conductor region 203 are in contact, A buried connection hole having a lower contact resistance is formed.

〔The invention's effect〕

As described above, according to the present invention, a conductive material that does not easily generate nuclei of a refractory metal during the selective vapor deposition of a refractory metal is formed on the side wall of the connection hole, so that there is no void, encroachment, etc. Realizing a buried connection hole,
It becomes possible to obtain a buried connection hole having a low resistance and a stable value of contact resistance, thereby suppressing the occurrence of junction leakage.

[Brief description of the drawings]

1 (a) to 1 (d) are sectional views in the order of steps for explaining a first embodiment of the present invention, and FIGS. 2 (a) to 2 (e) show a second embodiment of the present invention. FIG. 3 is a sectional view for explaining a conventional method of manufacturing a semiconductor device; FIG. 4 is a cross-sectional view for explaining another conventional method of manufacturing a semiconductor device; FIG. 5 is a cross-sectional view for explaining a problem of a conventional method of manufacturing a semiconductor device. 101, 201, 301 ... semiconductor substrate, 102, 202, 302 ... element isolation region, 103, 203, 303 ... conductor region, 104, 204, 304 ... insulating film, 105, 205, 305 ... connection hole, 106, 106a, 206, 206a ...
Titanium nitride, 107,307 …… Tungsten, 208,208a ……
Titanium, 209 ... Titanium silicide, 210 ... Molybdenum, 311
... silicon film, 312 ... hollow.

Continuation of the front page (56) References JP-A-3-280533 (JP, A) JP-A-3-21016 (JP, A) JP-A-2-194637 (JP, A) JP-A-2-83977 (JP) JP-A-2-47830 (JP, A) JP-A-63-237551 (JP, A) JP-A-62-112366 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB Name) H01L 21/28 H01L 21/3205

Claims (4)

(57) [Claims] 1. A method for forming a wiring layer of a semiconductor device, comprising: forming a conductor region and an element isolation region on a surface of a semiconductor substrate made of silicon; and forming a connection hole with an upper wiring layer on the conductor region. Forming an insulating film having: a step of surrounding the side wall of the connection hole with a conductive material that is less likely to become a nucleation site than the surface of the semiconductor substrate in the selective vapor deposition of a refractory metal; A step of diffusing impurities into the exposed surface of the semiconductor substrate; a step of embedding the inside of the connection hole with the high melting point metal by selective vapor deposition of a high melting point metal; and Forming the upper wiring layer connected to the conductor region. 2. The method of manufacturing a semiconductor device according to claim 1, wherein said conductive material comprises only titanium nitride. 3. The surface of the conductive material at a portion of the bottom surface of the connection hole that connects to the surface of the semiconductor substrate is made of titanium silicide, and that is connected to the titanium silicide and covers a side wall of the connection hole. 2. The method of manufacturing a semiconductor device according to claim 1, wherein said material comprises titanium nitride. 4. The method according to claim 1, wherein the refractory metal is tungsten, titanium, or molybdenum.