JPH05121354A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a semiconductor device which has a thick high-melting-point- metal film (tungsten film) selectively formed within a contact hole and has a small and highly reliable contact electrode excellent in flatness. CONSTITUTION:A barrier metal (titanium nitride) is deposited inside a contact window, and then high melting point metal (tungsten) is deposited until the contact window is filled up completely. To be concrete, as shown by step B, a titanium nitride film 8 is formed inside the contact window 4 reaching an n-type silicon diffusion region 2, and then a tungsten film 6 is formed. Next, as shown by step C, the tungsten film 6 and the titanium nitride film 8 excluding the part in the contact window 4 are removed. Accordingly, the junction breakage by the reaction with the silicon substrate at the time of growth of a conventional tungsten film can be prevented, and also a thick tungsten film (high melting point film) can be formed easily, and besides the contact part can be planarized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to forming a highly reliable contact electrode having a fine area between a diffusion phase region formed on a semiconductor substrate and a wiring layer. The present invention relates to a method for manufacturing a semiconductor device.

[0002]

2. Description of the Related Art In order to meet the demands for higher integration and higher speeds of semiconductor devices, it is indispensable to miniaturize the elements and planarize the devices so as to cope with shallow junctions and multilayer interconnections. Therefore, in the contact formation portion, a technique for selectively growing a refractory metal by vapor phase epitaxy to alleviate the step difference of the contact window and to secure the step coverage of the wiring layer has been put into practical use.

This conventional technique will be described with reference to FIG.
FIG. 3 is a sectional view showing a process flow of the prior art,
First, as shown in step A, the P-type silicon semiconductor substrate 1
After arsenic is introduced by an ion implantation method to form the N-type silicon diffusion region 2, a silicon oxide film 3 is formed and a contact window 4 reaching the N-type silicon diffusion region 2 is formed. Next, as shown in step B, the tungsten film 6 which is a refractory metal film is exposed in the contact window 4 by a vapor phase growth method using WF ₆ as a main source gas.
It selectively grows only on the type silicon diffusion region 2. Finally, as shown in Steps C to D, the aluminum film 7 is entirely covered by the sputtering method and PR5 is performed to form a wiring layer.

[0004]

By the way, in the method of manufacturing a semiconductor device according to the above-mentioned prior art, the tungsten film 6 is used.
The following reactions are mainly used for selective growth of. 2WF ₆ + 3Si → 2W + 3SiF ₄ Therefore, it proceeds while reacting with the silicon exposed in the contact window 4, and as a result, the contact window 4
The difference in level difference occurs. If the thickness of the tungsten film 6 is increased in order to prevent the reduction of the step, there is a drawback that the reaction between tungsten and silicon reaches the PN junction and a leak current is generated.

Therefore, an object of the present invention is to provide a method of manufacturing a semiconductor device which eliminates the above-mentioned drawbacks, and more specifically, to improve the height of a tungsten film or the like without destroying a PN junction formed on a silicon substrate. It is an object of the present invention to provide a method for manufacturing a semiconductor device, which enables a thicker film of a melting point metal and can easily realize a fine and highly reliable contact electrode having excellent flatness.

[0006]

The present invention is characterized by forming a barrier metal in the contact window and then forming a refractory metal until the contact window is completely filled. To manufacture the semiconductor device. That is, the present invention is: (1) a step of selectively providing a contact window to the semiconductor element in an insulating film that covers the substrate on which the semiconductor element is formed, (2) a step of completely covering the barrier metal by a sputtering method, (3) A step of completely covering the barrier metal with a refractory metal by vapor deposition, (4) a step of removing the barrier metal and refractory metal other than in the contact window by an etch back method, (5) a wiring metal pattern −
And a step of forming wiring, the manufacturing method of the semiconductor device.

The present invention will be described in detail below. According to the present invention, a barrier metal is formed in a contact window, and then,
The feature is that a refractory metal is formed until the contact window is completely filled. By forming this barrier metal, reaction with a silicon substrate during conventional tungsten film (refractory metal film) growth is performed. In addition to preventing the junction breakdown due to, the tungsten film (high melting point metal film) can be easily thickened and the contact portion can be flattened. In the present invention, the barrier metal is not particularly limited, but titanium nitride is preferable, and the refractory metal is preferably tungsten.

[0008]

Embodiments of the present invention will be described in detail below with reference to FIGS. 1 and 2. (Embodiment 1) FIG. 1 is a sectional view showing a process flow of a semiconductor device according to a first embodiment of the present invention. First, as shown in process A, arsenic is formed on a P-type silicon semiconductor substrate 1. A silicon oxide film 3 is deposited as an insulating film on the entire surface of the N-type silicon diffusion region 2 formed by ion implantation, and a contact window 4 is opened by a photoetching method.

Next, as shown in step B, a titanium nitride film 8 is formed as a barrier metal on the silicon oxide film 3 and the contact window 4 by sputtering to have a film thickness of 500 to 1800 angstroms. A tungsten film 6 as a refractory metal is formed by vapor phase epitaxy until the contact window 4 is completely covered. Thereafter, as shown in step C, the tungsten film 6 on the silicon oxide film 3 other than the contact window 4 is removed by etching with CF ₄ gas, and the titanium nitride film 8 on the silicon oxide film 3 is also removed.
Are removed by etching with Cl-based gas.

Finally, as shown in steps D to E, an aluminum film 7 is formed by a sputtering method, PR5 is performed, and
A contact electrode and a wiring layer are formed. The contact electrode thus formed has the advantage that the contact window 4 is completely filled with the barrier metal and the refractory metal, so that there is no step due to the contact window 4 and the wiring can be miniaturized.

(Embodiment 2) FIG. 2 is a sectional view showing a process flow of a semiconductor device according to a second embodiment of the present invention. First, like the first embodiment, steps A to C are performed. As shown, contact portions are formed. In addition, these steps A to C
Are the same as those in the first embodiment, and will be omitted. In the second embodiment, as shown in steps D to F, the aluminum film 7 is formed by the sputtering method, PR5 is performed, and the contact electrode and the wiring portion are removed by isotropic etching.

After that, a titanium film 9 and a platinum film 10 are formed by a continuous sputtering method, PR5 and the titanium film 9 and the platinum film 10 on PR5 are removed by a lift-off method, and finally,
PR11 is applied and gold 12 wiring is formed by a plating method. In the second embodiment, since the wiring is formed by the plating method, gold can be easily patterned and can be used as the wiring.

[0013]

As described in detail above, according to the present invention, after forming the barrier metal in the contact window, the refractory metal is formed until the contact window is completely filled. The refractory metal film can be made thicker without destroying the PN junction formed in the second step, and further, there is an effect that a fine and highly reliable contact electrode excellent in flatness can be easily realized. Further, the present invention also has an advantage that the wiring layer can be formed by using the plating method.

[Brief description of drawings]

FIG. 1 is a sectional view showing a process flow of a semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a process flow of a semiconductor device according to a second embodiment of the present invention.

FIG. 3 is a sectional view showing a process flow of a conventional semiconductor device.

[Explanation of symbols]

 1 P-type semiconductor silicon substrate 2 N-type silicon diffusion region 3 Silicon oxide film 4 Contact window 5 PR 6 Tungsten film 7 Aluminum film 8 Titanium nitride film 9 Titanium film 10 Platinum film 11 PR 12 Gold

Claims (1)

[Claims] 1. A step of selectively providing a contact window to a semiconductor element on an insulating film covering a substrate on which a semiconductor element is formed, (2) a step of covering the entire surface of a barrier metal by a sputtering method, (3) the above A step of entirely covering the refractory metal on the barrier metal by vapor deposition, (4) a step of removing the barrier metal and refractory metal other than in the contact window by an etch back method, (5) a pattern of the wiring metal And a step of forming wiring, the manufacturing method of the semiconductor device.