JPH0582968B2 - - Google Patents

Description

[Detailed Description of the Invention] [Object of the Invention] (Field of Industrial Application) The present invention relates to a method of manufacturing a semiconductor device,
In particular, the present invention relates to a method of manufacturing a semiconductor device having wiring in which a connection portion with a semiconductor or metal surface is embedded with a metal film such as tungsten.

(Prior Art) Conventionally, in a semiconductor device, for example, electrode wiring of a lower layer element and upper layer wiring have been formed by depositing metal or metal silicide by a sputtering method. This method will be explained with reference to FIG.
That is, for example, a SiO ₂ film 22 is formed as an insulating film on the N ₊ or P ₊ silicon wiring layer 21 formed on the substrate 20.
An opening 23, that is, a through hole is formed in (FIG. 4a). Thereafter, a tungsten film 24 is formed by DC magnetron sputtering (FIG. 4b). In the case of film formation using the sputtering method, the film formation rate is basically determined by the amount of sputtered particles supplied, so the growth rate is high in areas where the angle of view to the sputtered particles is large, such as at the shoulder of a step, and the pores are less likely to open. Inside the area, the growth rate is slow because the prospect angle is small. As a result, an overhang occurs as shown in FIG. 4b, and a cavity is formed in the opening.

As a method to overcome the above problems, a method has been considered in which a tungsten film is formed by chemical vapor deposition using hydrogen and tungsten hexafluoride gas. By adopting this method, no overhang occurs at the stepped portion as shown in FIG. However, the adhesion between the tungsten film 25 and the lower oxide film 22 is weak, and the tungsten film 25 cannot withstand the stress between the substrate and peels off frequently, resulting in the formation of cavities 26 as shown in the figure. The surface shape of No. 25 loses flatness and makes subsequent pattern processing difficult. Furthermore, if the tungsten film is thinned to prevent peeling, the center of the opening becomes a recess, and an insulating film is deposited on the upper layer to form a second opening directly above the opening. In this case, since the thickness of the insulating film differs locally, it is difficult to perform uniform etching, which may result in poor contact at the connection portion.

(Problems to be Solved by the Invention) The present invention has been made in consideration of the above-mentioned problems. An object of the present invention is to provide a method for manufacturing a semiconductor device in which peeling of the metal film and oxide film does not occur in a method of forming a pattern of a metal film such as tungsten that extends over the top.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention forms an insulating film on the surface of a semiconductor or metal, and exposes a part of the semiconductor or metal to the insulating film. a step of providing an aperture, then a step of depositing a first metal film having good adhesion to the insulating film on the aperture and the insulating film by a chemical vapor deposition method; forming a film on the entire surface of the first metal film by chemical vapor deposition to fill the opening; and then processing the first and second metal films into a wiring pattern. A method of manufacturing a semiconductor device is provided.

(Function) According to the present invention, a first metal having good adhesion to the insulating film is placed between the second metal film, such as tungsten, and the insulating film, which is embedded in the opening formed in the insulating film, such as an oxide film. Since the film is interposed, peeling of the metal film on the surface of the insulating film and gaps between the openings will not occur.

Further, according to the present invention, since the first and second metal films are formed by chemical vapor deposition, overhangs do not occur at stepped portions, and therefore the film thickness is sufficient to fill the openings. Even if a metal film is deposited,
The surface of the metal film can be flattened, and therefore it can be processed into a wiring pattern.

On the other hand, by forming a metal film on the side wall of the opening and reducing the size of the opening to be filled, the minimum metal film thickness required for filling is reduced, and therefore the capacitance between wirings is also reduced.

(Example) Hereinafter, an example of the method for manufacturing a semiconductor device according to the present invention will be described.

First, a first embodiment of the present invention will be described with reference to FIG. As shown in FIG. 1a, an approximately 1.2 μm Si insulating film is formed on the arsenic (A _s ) heavily doped layer 10 formed on a 5 Ωcm P-type (100) silicon substrate 16 _.
After forming the O ₂ film 11 by atmospheric pressure CVD method, it is etched at a desired location with a diameter of 0.4 μm by reactive ion etching, etc.
An opening 15 is provided. Next, 650 as shown in Figure 1 b.
Hydrogen (H ₂ ) was introduced at a partial pressure of 0.15 Torr and Tic ₄ was introduced at a partial pressure of 0.05 Torr in a reduced pressure CVD device at ℃.
Titanium (Ti) film 1 which is the first metal film with a thickness of about 200 Å
2, and after evacuating the inside of the device, hydrogen (H ₂ ) was applied at a substrate temperature of 400°C and a partial pressure of 0.2 Torr.
Tungsten hexafluoride (WF ₆ ) is introduced at 0.03 Torr to form the tungsten film 13, which is the second metal film.
The openings 15 were filled by depositing 0.2 to 0.3 μm. Thereafter, by processing the titanium film 12 and the tungsten film 13 into a desired wiring pattern, simultaneous formation of the upper layer wiring and the buried wiring is realized (FIG. 1b).

When the contact resistance with the silicon substrate was measured, it was 1×10 ^-6 Ωcm ² and the current-voltage characteristics showed good ohmic properties.

In the above embodiment, the titanium film 12 was formed as the first metal film, but a tungsten-silicon alloy film may be formed instead. In the above embodiment, after forming the openings 15 at desired locations in the _{SiO 2} film 11 as shown in FIG. Partial pressure on semiconductor substrate
Hydrogen (H ₂ ) at 0.06 Torr, SiH ₄ at 0.12 Torr,
It is formed by introducing tungsten hexafluoride (WF ₆ ) at 0.001 Torr and depositing a 500 Å tungsten-silicon alloy film with an excessive silicon content. After this, the partial pressure is changed as in the first embodiment.
By introducing hydrogen (H ₂ ) at 0.2 Torr and tungsten hexafluoride (WF ₆ ) at 0.03 Torr, the second
A tungsten film 13 with a thickness of 0.3 μm is deposited as a metal film. If wiring is processed after this, the same effect as in the case of the titanium film described above can be obtained.

As mentioned above, if the method according to the present invention is used, there will be no film peeling or unevenness of the Si _{O 2} film 11 due to film peeling, and there will be no gaps in the openings 15 such as through holes or contact holes, and the holes can be opened with good reliability. I was able to embed part 15.

Next, as a second embodiment of the present invention, a manufacturing method including a step of forming an opening in a Si _{O 2} film and then forming a metal layer reacted with a fluoride gas in the opening is performed. This will be explained using figures.

First, as shown in Figure 2a, arsenic (As) is applied to a 5Ωcm P-type (100) silicon substrate 1 at 30KeV in a 3×10 ¹⁵
After implanting cm ^-2 and performing heat treatment at 900°C for 40 minutes to form the N ⁺ diffusion layer 2, the substrate temperature was increased to 400°C using tungsten hexafluoride (WF ₆ ) and argon (Ar).
A tungsten wiring layer 3 of about 500 Å is formed by chemical vapor deposition at a temperature of 0.2 Torr.
Next, using S _i H ₄ and N ₂ O under a pressure of 0.35 Torr, approx.
A _{SiO 2} film 11 is deposited as an insulating film with a thickness of 1.2 μm, and then an opening 15 with a diameter of 0.4 μm is formed by reactive ion etching or the like. After that, the temperature of the substrate 1 is
A polycrystalline silicon film 4 with a thickness of 0.1 μm is deposited on the openings 15 and 4 using low pressure chemical vapor deposition (CVD) at 600°C.
It is deposited on the S _i O ₂ film 11 . Thereafter, as shown in FIG. 2b, the entire polycrystalline silicon 4 is anisotropically etched by reactive ion etching using a chlorine gas such as BBr ₃ -C ₂ to form a silicon film 4a on the side wall of the opening 15. leave. Next, tungsten hexafluoride (WF ₆ ), which is a tungsten fluoride gas, and argon (Ar) were heated at a pressure of 0.2 Torr and a substrate 1 temperature of 400°C.
The silicon film 4a is used to reduce tungsten hexafluoride (WF ₆ ), and the side wall silicon film 4a is reduced.
are all replaced with a tungsten film 5 as shown in FIG. 2c. When all of the 0.1 μm silicon film 4a reacts with tungsten hexafluoride (WF ₆ ), a tungsten film 5 of about 500 Å is formed.

After that, reduced pressure CVD is performed as shown in Figure 2d.
Temperature of the substrate is 400℃ inside the device and partial pressure is applied.
Hydrogen (H ₂ ) at 0.06 Torr, S _i H ₄ at 0.12 Torr,
Tungsten hexafluoride (WF ₆ ) was introduced at a pressure of 0.001 Torr, and a tungsten-silicon alloy film 12 with an excess silicon content of 500 Å was formed as the first metal film, followed by hydrogen (H ₂ ) at a partial pressure of 0.2 Torr. Tungsten hexafluoride (WF ₆ ) is introduced at 0.03 Torr to deposit a 0.1 μm second metal film, here the tungsten film 13. Then, the laminated films 12 and 13 are patterned.

According to this embodiment, the thickness of the tungsten-silicon alloy film 12, which is the first metal film, and the tungsten film 13, which is the second metal film, can be made thinner by the thickness of the metal film 5. Etching is easy, and there is no peeling of the film or unevenness of the S _i O ₂ film 11 due to peeling of the film, and no gaps are found in the openings 15, so the openings 15 can be reliably etched. I was able to embed it.

The contact resistance between the tungsten wiring layer 3 and the highly concentrated arsenic (As) doped silicon layer 2 is 5×10 ^-7 Ω.
cm ² and showed good ohmic properties.

As explained above, according to the present invention, the metal film does not peel off, so that wiring pattern processing can be performed reliably. Furthermore, since the surface is flat, process reliability is also excellent. For example, even if a CVD oxide film is formed on the entire surface, through holes are formed over the contact holes, and an upper wiring layer is further provided, contact failure with the lower wirings 12 and 13 will not occur. Furthermore, if the metal film 5 is formed on the side wall of the opening 15, the thickness of the metal film required for embedding can be reduced, making it easy to pattern the wiring and reducing the capacitance between the wirings.

In the second embodiment described above, even when the tungsten wiring layer 3 is not formed, that is, even when the S _i O ₂ film 11 is formed directly on the N ⁺ diffusion layer 2,
A similar effect can be obtained. In this case, the final structure obtained is shown in FIG. Here, the same parts as in FIG. 2 are indicated by the same symbols.

In each of the above examples, titanium or a tungsten-silicon alloy was used as the first metal, and tungsten was used as the second metal, but the present invention is not limited to these, and titanium (Ti) was used as the first metal. , zirconium (Zr), hafnium (Hf), niobium (Nb), tantalum (Ta), and their silicides (alloys with silicon), nitrides,
Alternatively, it may be a silicide of molybdenum (Mo) or tungsten (W), and the same effect can be obtained even if the second metal is molybdenum (Mo) or a silicide thereof in addition to tungsten (W). It will be done. Further, in the embodiment shown in FIGS. 2 and 3, tungsten is used as the metal formed on the side wall of the opening 15, but molybdenum may also be used.

Further, the lower layer of the _Si O ₂ film 11 is made of an N ⁺ or P ⁺ silicon substrate, titanium, zirconium, hafnium, niobium, tantalum, chromium, molybdenum, tungsten and their silicides or nitrides, or nickel, palladium, It may be a metal film mainly composed of platinum and silicides thereof, or aluminum or copper.

〔Effect of the invention〕

As described above, according to the present invention, when filling an opening such as a contact hole or a through hole formed in an insulating film with a metal film such as tungsten, an insulating film is formed between the metal film and the insulating film. Since the first metal film having good adhesion to the film is interposed, the metal film does not peel off and pattern processing can be performed reliably.

Furthermore, since no gaps are formed in the openings, the flatness is also good.

On the other hand, by forming a metal film on the side wall of the opening and reducing the area of the opening to be filled, the minimum metal film thickness required for filling is reduced, making patterning easier and reducing the capacitance between interconnects. Decrease.

[Brief explanation of drawings]

FIG. 1 is a process sectional view showing an embodiment of the present invention;
2 and 3 are process sectional views showing another embodiment of the present invention, and FIGS. 4 and 5 are process sectional views showing a conventional example. 1, 16, 20... silicon substrate, 2, 10,
21...N ⁺ or P ⁺ diffusion layer, 3... Lower metal wiring, 11, 22... Insulating film, 12... First metal film, 13... Second metal film, 15, 23... Opening Part, 4, 4a... Conductor film, 5... Metal film, 2
4,25...Metal film.

Claims (1)

[Claims] 1. A step of forming an SiO ₂ film on the surface of a semiconductor or metal, and providing an opening in the SiO ₂ film so that a part of the semiconductor or metal is exposed; depositing a silicon film on the opening and the SiO ₂ film by chemical vapor deposition, leaving the silicon film self-aligned with the sidewall of the opening by anisotropic etching;
Thereafter, a step of replacing the silicon film with a tungsten or molybdenum metal film by reacting with a tungsten or molybdenum fluoride gas, and then a step of replacing the silicon film with a tungsten or molybdenum metal film, and then applying titanium, zirconium, hafnium, niobium, tantalum on the opening and the SiO ₂ film. and a step of depositing a first metal film composed of any of these silicides, nitrides, tungsten, or molybdenum silicides by chemical vapor deposition, and then a step of depositing tungsten or molybdenum and any of these silicides. forming a second metal film made of one of silicides on the entire surface of the first metal film by chemical vapor deposition to fill the opening; 1. A method for manufacturing a semiconductor device, comprising the step of processing a metal film into a wiring pattern according to step 2. 2 The metal under the SiO ₂ film is titanium, zirconium,
Either hafnium, niobium, tantalum, chromium, molybdenum, tungsten and their silicides or nitrides, or nickel, palladium, platinum and their silicides, or metals whose main components are aluminum or copper. Claim 1
A method for manufacturing a semiconductor device according to section 1.