JPH0590199A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To provide a method of manufacturing a semiconductor device by which a high-melting point metal film to be formed in a contact hole is prevented from reacting with a silicon semiconductor substrate to avoid disadvantages such as an increase in a leakage current, the flatness of a wiring layer formation surface is superior and a wiring layer is formed into a fine pattern. CONSTITUTION:A silicon oxide film 3 is first formed on a semiconductor substrate 1 and a contact hole 4 is selectively made in this film 3. Then, a polycrystalline silicon film 5 is selectively formed in this hole 4 by a vapor growth method. After that, a tungsten film 6 is selectively formed on the film 5 by a vapor growth method. In this case, the film 5 acts as a sacrifice layer and the tungsten film can avoid reacting with the substrate 1. Moreover, as the film 6 can be made thick, the flatness of a wiring layer formation surface can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device in which a diffusion layer formed on the surface of a semiconductor substrate and a wiring layer formed on the semiconductor substrate via an insulating film are electrically connected through a contact hole. Manufacturing method.

[0002]

2. Description of the Related Art Recently, there has been a demand for higher integration and higher speed of semiconductor devices, and these demands have been met by miniaturization of elements and shallow junction. Further, it is said that it is necessary to flatten the surface on which the wiring layer is formed in order to deal with multilayer wiring.

By the way, particularly in a semiconductor device provided with a shallow junction, in order to prevent the metal constituting the wiring layer from reacting with the semiconductor substrate at the time of forming the wiring layer, the semiconductor is prevented from being destroyed. A barrier metal made of a refractory metal nitride is provided between the substrate and the wiring layer. In addition, by selectively growing refractory metal in the contact holes using vapor phase epitaxy, the step difference on the wiring layer formation surface due to the contact holes is mitigated, and the step coverage of the barrier metal and the wiring layer is secured. The technology to do so has begun to be put to practical use.

3A and 3B are cross-sectional views showing, in the order of steps, a method of manufacturing a conventional semiconductor device in which a refractory metal film is provided in a contact hole.

First, as shown in FIG. 3A, arsenic (As) is selectively introduced into the surface of a P-type silicon semiconductor substrate 21 by an ion implantation method to form an N-type silicon region 22. Form. Then, a silicon oxide film 23 is formed on the entire surface, and a contact hole 24 reaching the N-type silicon region 22 from the surface of the silicon oxide film 23 is formed.

Next, tungsten, which is a refractory metal, is selectively grown on the N-type silicon region 22 exposed in the contact hole 24 by a vapor phase growth method using WF ₆ as a main source gas. , A tungsten film 25 is formed.

Then, as shown in FIG. 3B, a titanium nitride film 2 is formed as a barrier metal on the entire surface by a sputtering method.
6 is formed, and this titanium nitride film 26 is patterned so as to cover at least the contact hole 24. After that, an aluminum film 27 is formed on the entire surface by a sputtering method, and the aluminum film 27 is patterned to form a wiring layer.

[0008]

However, the above-mentioned conventional method of manufacturing a semiconductor device has the following problems. That is, in the conventional semiconductor device manufacturing method, in order to selectively grow the tungsten film, the reaction represented by the following chemical formula 1 is mainly used.

[0009]

[Chemical formula 1] 2WF ₆ + 3Si → 2W + 3SiF ₄

That is, since the growth of the tungsten film proceeds while reacting with the silicon exposed in the contact hole,
If an attempt is made to increase the film thickness of the tungsten film in order to reduce the step difference on the wiring layer formation surface due to the contact hole, the reaction between tungsten and silicon reaches the PN junction, which causes an increase in leak current.

The present invention has been made in view of the above problems, and manufactures a semiconductor device capable of improving the flatness of a wiring layer forming surface without breaking a shallow junction provided on a semiconductor substrate. The purpose is to provide a method.

[0012]

A method of manufacturing a semiconductor device according to the present invention comprises a step of forming an insulating film on a semiconductor substrate and a contact hole reaching a surface of the semiconductor substrate at a predetermined portion of the insulating film. Forming step, selectively forming a polycrystalline silicon film in the contact hole by vapor phase growth method, and selectively forming a refractory metal film on the polycrystalline silicon film by vapor phase growth method And a process.

[0013]

In the present invention, a polycrystalline silicon film is selectively formed in the contact hole by the vapor phase growth method, and then a high melting point metal such as tungsten is formed on the polycrystalline silicon film by the vapor phase growth method. Forming a high melting point metal film. That is, in the present invention, the polycrystalline silicon film is interposed between the semiconductor substrate and the refractory metal film. As a result, the polycrystalline silicon film acts as a sacrificial layer when the refractory metal film is formed, and the reaction between the refractory metal film and the semiconductor substrate can be avoided. Therefore, the thickness of the refractory metal film can be increased, so that the PN junction is not destroyed and
The flatness of the wiring layer formation surface can be improved.

[0014]

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

1A to 1C are sectional views showing a method of manufacturing a semiconductor device according to the first embodiment of the present invention in the order of steps.

First, as shown in FIG. 1A, arsenic is selectively ion-implanted into the surface of a P-type silicon semiconductor substrate 1 to form an N-type silicon region 2, and then the entire surface of the semiconductor substrate 1 is covered. A silicon oxide film 3 is formed. After that, contact holes 4 reaching the N-type silicon region 2 from the surface of the silicon oxide film 3 are selectively formed.

Next, as shown in FIG. 1B, SiH ₂
A polycrystalline silicon film 5 is selectively formed only on the N-type silicon region 2 exposed in the contact hole 4 by a vapor phase growth method using a gas mixture of Cl ₂ , HCl and N ₂ . The polycrystalline silicon film forming conditions at this time are, for example,
Temperature 650 to 750 ℃, reactor pressure 100 to 200T
The partial pressure of orr, SiH ₂ Cl ₂ and HCl is 2 to 5 T, respectively.
orr. The thickness of the polycrystalline silicon film 5 is, eg, 0.1 to 0.3 μm. Next, arsenic is introduced into the polycrystalline silicon film 5 by using the ion implantation method. After that, by a vapor phase growth method using WF ₆ as a main source gas, tungsten, which is a refractory metal, is selectively grown only on the polycrystalline silicon film 5 until the contact hole 4 is filled, and thus the tungsten film 6 is formed. To get

Next, as shown in FIG. 1C, an aluminum film 7 is formed on the entire surface by a sputtering method, and the aluminum film 7 is patterned to form a wiring layer. In this way, the semiconductor device is completed.

In this embodiment, the polycrystalline silicon film 5 is used.
Serves as a sacrificial layer during the growth of tungsten, and the reaction between tungsten and the silicon semiconductor substrate can be avoided.
Therefore, the tungsten film can be made sufficiently thick, and it is not necessary to separately provide a barrier metal layer. Further, since it is possible to suppress a step on the wiring layer forming surface due to the contact hole, it is possible to miniaturize the wiring layer.

2A to 2C are sectional views showing a method of manufacturing a semiconductor device according to the second embodiment of the present invention in the order of steps. The present embodiment is applied to the case where contact holes having different depths are provided.

First, as shown in FIG. 2A, arsenic is selectively ion-implanted into the surface of a P-type silicon semiconductor substrate 11 to form an N-type silicon region 12, and then a silicon oxide film 13 is formed on the entire surface. To form. After that, a polycrystalline silicon film is formed on the silicon oxide film 13 by using the vapor phase growth method, the polycrystalline silicon film is patterned, and then impurities are introduced into the polycrystalline silicon film by the ion implantation method. , A resistance element 18 having a predetermined resistivity is formed.

Next, as shown in FIG. 2B, after the BPSG film 19 is formed on the entire surface by a vapor phase growth method, a heat treatment is performed to perform a reflow treatment to flatten the surface of the BPSG film 19. Then, by anisotropic dry etching, this B
First contact holes 14 reaching the N-type silicon region 12 from the surface of the PSG film 19 are selectively formed. next,
Similar to the first embodiment, the polycrystalline silicon film 15 is selectively formed only in the first contact hole 14. At this time, the position of the upper surface of the polycrystalline silicon film 15 is set to the resistance element 1
8 so as to be aligned with the position of the upper surface. When the polycrystalline silicon film 15 becomes thicker, a polycrystalline silicon film doped with arsenic in advance is formed.

Next, as shown in FIG. 2C, a second contact hole reaching the resistance element 18 from the surface of the BPSG film 19 is selectively formed by anisotropic dry etching. After that, similarly to the first embodiment, tungsten is selectively grown until the first contact hole 14 and the second contact hole are filled, and the tungsten film 16 is obtained. Then, an aluminum film 17 is formed on the entire surface by a sputtering method, and the aluminum film 17 is patterned to form a wiring layer.

In the present embodiment, even when the contact holes having different depths are provided, the thickness of the polycrystalline silicon film interposed between the semiconductor substrate and the tungsten film is appropriately controlled, so that Similar to the first embodiment, excellent flatness can be obtained, and the wiring layer can be formed in a fine pattern.

[0025]

As described above, according to the present invention,
After the polycrystalline silicon film is selectively formed in the contact hole, the refractory metal film is selectively formed on the polycrystalline silicon film, so that the high melting point can be achieved without breaking the shallow junction provided in the silicon substrate. The metal film can be made thicker, and the wiring layer can be formed in a fine pattern on the surface having excellent flatness.

[Brief description of drawings]

1A to 1C are cross-sectional views showing a method of manufacturing a semiconductor device according to a first exemplary embodiment of the present invention in the order of steps.

2A to 2C are cross-sectional views showing a method of manufacturing a semiconductor device according to a second exemplary embodiment of the present invention in the order of steps.

3A and 3B are cross-sectional views showing a conventional method of manufacturing a semiconductor device in the order of steps.

[Explanation of symbols]

 Semiconductor substrates 2, 12, 22; N-type silicon regions 3, 13, 23; Silicon oxide films 4, 14, 24; Contact holes 5, 15, 25; Polycrystalline silicon films 6, 16; Tungsten Films 7, 17, 27; Aluminum film 18; Resistive element 19; BPSG film 26; Titanium nitride film

Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H01L 21/90 D 7353-4M

Claims (1)

[Claims] 1. A step of forming an insulating film on a semiconductor substrate, a step of forming a contact hole reaching a surface of the semiconductor substrate at a predetermined portion of the insulating film, and a step of forming a contact hole in the contact hole by a vapor phase growth method. A method of manufacturing a semiconductor device, comprising: a step of selectively forming a polycrystalline silicon film; and a step of selectively forming a refractory metal film on the polycrystalline silicon film by a vapor phase growth method.