JP2905648B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a method for manufacturing a semiconductor device, and more particularly to an improved method for preventing silicon precipitation in a contact hole during sintering of aluminum alloy wiring. The present invention relates to a method for manufacturing a semiconductor device.

[0002]

2. Description of the Related Art FIG. 3 is a sectional view of a contact portion of a conventional semiconductor device having a single-layer aluminum wiring.

Referring to FIG. 3, an n ⁺ layer 2 is formed on a main surface of a silicon substrate 1. An oxide film 3 is formed on a silicon substrate 1. In the oxide film 3, the n ⁺ layer 2
A contact hole 4 for exposing a part of the surface is formed. An aluminum wiring layer 5 containing silicon is provided on silicon substrate 1 so as to be connected to n ⁺ layer 2 through contact hole 4. At the interface where the n ⁺ layer 2 and the aluminum wiring layer 5 are in contact with each other, P-type silicon 4 (referred to as silicon deposition) that has been subjected to solid phase epitaxial growth is deposited.

Next, a conventional method for forming an aluminum alloy wiring will be described. Referring to FIG. 3, silicon substrate 1
The n ⁺ layer 2 is formed in the main surface of the substrate by ion implantation. An oxide film 3 is formed on a silicon substrate 1. By selectively etching oxide film 3, contact hole 4 for exposing a part of the surface of n ⁺ layer 2 in oxide film 3 is opened. Then, on the silicon substrate 1,
An aluminum wiring 5 containing silicon is deposited by a sputtering method. The aluminum wiring 5 is patterned. Aluminum wiring 5
After patterning, a semiconductor device is formed through various heat treatment processes such as a hydrogen sintering process.

At the time of the above-mentioned heat treatment step, for example,
Hydrogen sintering, i.e.,
After heating for about 1 hour to 1 hour, 0.3 to 0.5% by weight of silicon (1 to 2%) contained in the aluminum wiring 5
Is solid-dissolved in the aluminum wiring 5, and silicon 6 undergoes solid phase epitaxial growth at the interface between the n ⁺ layer 2 and the aluminum wiring 5 in the contact hole 4, thereby depositing silicon 6. Since the silicon 6 has P-type characteristics, a pn junction is formed at the interface between the n ⁺ layer 2 and the silicon 6. Therefore, the conductive characteristics can be obtained only from one direction, and the product yield is reduced due to poor contact resistance.

[0006] Silicon deposition is particularly prominent in contact holes having a diameter of 1.3 µm or less. Therefore,
Conventionally, as shown in FIG. 4, a barrier metal 7 such as TiN is coated on the bottom and side walls of the contact hole 4 to form an ohmic contact between the aluminum wiring 5 and the n ⁺ layer 2. In addition, the occurrence of contact resistance failure was suppressed.

[0007]

In a conventional semiconductor device, as shown in FIG. 4, silicon deposition is prevented by forming a barrier metal 7. However, there has been a problem that the production cost is increased due to the introduction of a sputtering apparatus and the throughput is reduced due to an increase in the number of steps.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and it is possible to prevent silicon dissolved in aluminum alloy wiring from growing in solid-phase epitaxial growth in a contact hole. Improved to
It is an object to provide a method for manufacturing a semiconductor device.

[0009]

In the method of manufacturing a semiconductor device according to the present invention, first, a silicon substrate provided with a conductive region is prepared. An oxide film is formed on the silicon substrate. A contact hole for exposing a part of the surface of the conductive region is formed in the oxide film.
An aluminum alloy wiring containing silicon is formed on the silicon substrate so as to be connected to the conductive region through the contact hole. 350 ° C. above silicon substrate
Inserted into a heat treatment furnace maintained at a temperature of
Below, it is called low-temperature insertion. ), The temperature in the heat treatment furnace is 425 ° C. to 4 ° C.
The temperature is raised to 50 ° C, and at that temperature the aluminum alloy wiring
Perform sinter processing.

[0010]

According to the method of manufacturing a semiconductor device of the present invention, a silicon substrate on which an aluminum alloy wiring is formed is inserted at a low temperature.
As a result, the silicon dissolved in the aluminum alloy wiring is fixed on the oxide film, so that the movement of silicon into the contact hole is suppressed, and the silicon contributing to solid phase epitaxial growth in the contact hole is reduced.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

Referring to FIG. 1, n ⁺ layer 2 is formed on the main surface of silicon substrate 1 by ion implantation. An oxide film 3 is formed on a silicon substrate 1. Oxide film 3 is selectively etched, thereby opening contact hole 4 for exposing a part of the surface of n ⁺ layer 2. Through the contact hole 4 so as to be connected to the n ⁺ layer 2,
Aluminum alloy wiring 5 containing silicon is formed on silicon substrate 1 by sputtering. The aluminum alloy wiring 5 is patterned. Next, a hydrogen sintering process is performed. The hydrogen sintering is performed, for example, at a temperature of 425 to 450 ° C.

In this embodiment, when the hydrogen sintering process is performed ,
At a temperature of 425 ° C. or lower, preferably 350 to 400
The wafer subjected to the above-described processing is inserted into a sinter furnace maintained at a temperature of ℃, and heat-treated at a temperature of 425 ℃ or less. Thereafter, the furnace temperature is increased at a rate of, for example, 5 ° C./min.
After the furnace temperature is stabilized at 425 ° C. to 450 ° C., hydrogen sintering is performed, and then the wafer is pulled out. Hereinafter, this method is referred to as low-temperature insertion hydrogen sintering.

When the low-temperature insertion hydrogen sintering is performed,
First, when inserted into a wafer furnace at 350 to 400 ° C., a small amount of 0.3% by weight or less of solid-dissolved silicon moves toward the contact hole 4 and undergoes solid-phase epitaxial growth, as shown in FIG. Then, nuclei grow as polycrystals on oxide film 3. This is the silicon nodule 8.

The silicon nodules 8 have a characteristic that, with a certain size of silicon nodule 8 as a boundary, those having a size larger than that grow, and those having a size smaller than that grow to melt and disappear.

According to the embodiment, since the wafer is inserted into the furnace at a low temperature, many small silicon nodules 8 remain on the oxide film 3. FIG. 2A shows a silicon nodule 8.
FIG. 4 is a diagram showing a state in which a lot of nuclei remain on the oxide film 3 as nuclei. Thereafter, when the wafer temperature is raised to the processing temperature of the hydrogen sintering, many nuclei of the silicon nodules 8 grow, and the solid solution silicon on the oxide film 3 is fixed. Therefore, the absolute amount of dissolved silicon that contributes to solid phase epitaxial growth decreases,
Temperature at which solid phase epitaxial growth is likely (425 to 450
C.) does not cause silicon deposition in the contact hole 4.

If the wafer is inserted into the furnace at the hydrogen sintering temperature (425 to 450 ° C.) as in the conventional method, the heating causes no small silicon nodules 8 to remain on the oxide film 3 and the large silicon nodules 8 remain. Only a small amount remains. FIG.
(B) is a diagram showing such a situation. According to the conventional method, melt a lot of small silicon nodules 8
Thus , during the hydrogen sintering process, it moves to the contact hole 4 and contributes to solid phase epitaxial growth. Therefore, silicon deposition easily occurs in the contact hole 4.

[0018]

As described above, according to the method of manufacturing a semiconductor device according to the present invention, since the silicon substrate on which the aluminum alloy wiring is formed is inserted at a low temperature , silicon dissolved in the aluminum alloy wiring is formed on the oxide film. And the movement of silicon into the contact hole is suppressed, and the amount of silicon contributing to solid phase epitaxial growth is reduced. As a result, silicon does not precipitate in the contact hole. According to the method according to the present invention, the processing can be performed only by the conventional sinter furnace, and there is no need to introduce a device such as a sputtering device. Therefore, a semiconductor device can be manufactured at low cost and low throughput.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a method of manufacturing a semiconductor device according to one embodiment of the present invention.

FIG. 2 is a diagram showing a comparison of the difference in the state of silicon nodule generation between the present embodiment and a conventional example.

FIG. 3 is a cross-sectional view illustrating a conventional method for manufacturing a semiconductor device.

FIG. 4 is a cross-sectional view showing a method for improving a conventional semiconductor device manufacturing method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Silicon substrate 2 n ⁺ layer 3 Oxide film 4 Contact hole 5 Aluminum alloy wiring containing silicon 8 Silicon nodule

Continuation of the front page (56) References JP-A-3-91240 (JP, A) JP-A-2-45925 (JP, A) JP-A-5-190489 (JP, A) JP-A-3-131102 (JP) JP-A-2-256272 (JP, A) JP-A-2-119222 (JP, A) JP-A 1-238013 (JP, A) JP-A-63-310115 (JP, A) 55-73868 (JP, A) JP-A-54-22767 (JP, A) JP-A-1-145834 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 21/28 H01L 21/3205

Claims (1)

(57) [Claims] A step of preparing a silicon substrate provided with a conductive region; a step of forming an oxide film on the silicon substrate; and exposing a part of the surface of the conductive region in the oxide film. forming a contact hole for the through contact holes, on the silicon substrate so as to be connected to the conductive area, 350 forming an aluminum alloy wiring, the silicon substrate including silicon Maintained at a temperature of ℃ ~ 400 ℃
425 ° C. to 45 ° C.
The temperature was raised to 0 ° C.
Performing a semiconductor device treatment .