JPH0758198A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To provide a manufacturing method for a semiconductor device which prevents a short circuit through residual tungsten between wirings and improves yield. CONSTITUTION:After a tungsten layer 48 is formed, etachback of the tungsten layer 48 is performed by dry etching. After the etchback is completed, an entire wafer is emmersed in an aqueous solution of 30% hydrogen peroxide at a temperature of 24 deg.C for 60 to 240 seconds. Next, an Al alloy which is to be a wiring material is deposited for a thickness of 8000Angstrom by sputtering and a wiring 50 is formed by photolithography and dry etching.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device including a step of burying tungsten in a contact hole or a via hole.

[0002]

2. Description of the Related Art In order to prevent electromigration and reduce contact resistance, a method of burying tungsten in a contact hole or a via hole and then forming a wiring has been conventionally used. This conventional method will be described with reference to FIG.

FIG. 3 is a cross-sectional view showing a method of burying tungsten in a contact hole and then forming a wiring. First, as shown in FIG. 3A, a contact hole 14 is formed in the insulating layer 12 formed on the semiconductor substrate 10.
To form. Next, as shown in FIG. 3B, an adhesion layer 16 for tungsten is formed on the inner surface of the contact hole 14 and the surface of the insulating layer 12 by the sputtering method. As the adhesion layer 16, a Ti layer, a TiN layer or the like is usually used. Next, as shown in FIG. 3C, tungsten is deposited on the surface of the semiconductor substrate 10 by the CVD method to form a tungsten layer 18. Next, the tungsten layer 18
Is etched back, and as shown in FIG. 3 (d),
A tungsten plug 20 is formed by leaving tungsten only in the contact hole 14. After that, spatter, C
Scrubber cleaning and QDR cleaning may be performed in order to remove foreign substances generated during VD, etch back, and the like. Next, as shown in FIG. 3E, an Al alloy is deposited by the sputtering method to form the wiring layer 22. Next, using photolithography, dry etching, etc.,
As shown in FIG. 3F, the wiring 24 is formed.

[0004]

In forming the tungsten layer 18 in the above steps, the insulating layer 12 and the adhesion layer 16 are formed.
Foreign matter may be present on the surface of the. What the present inventor found out about the influence of the foreign matter will be described with reference to FIG. FIG. 4 is a cross-sectional view showing foreign matter existing on the adhesion layer 16.

The present inventor has found that when a foreign substance 26 as shown in FIG. 4A is present on the surface of the adhesive layer 16 or the like,
When the entire surface of the tungsten layer 18 is etched back after the tungsten layer 18 (see FIG. 3C) is formed, as shown in FIG. 4B, the periphery of the foreign substance 26 and the adhesion layer 1 are removed.
It has been found that a tungsten residue 28 is generated between the contact layer 6 and the step 6 of the adhesion layer 16 caused by a foreign substance. It is considered that the cause of such a tungsten residue 28 is that the etch-back of tungsten is anisotropic etching performed by dry etching. Since such a tungsten residue 28 is not etched at all by dry etching during wiring formation, the tungsten residue 2
8 occurs, the wiring 30 as shown in FIG.
The formation of the above causes a short circuit between adjacent wirings, resulting in a decrease in yield. Further, it was found that the foreign matter 26 adhering to the adhesion layer 16 and the like was in a state of being glued to the adhesion layer 16 and the like by the tungsten residue 28 and could not be removed by the scrubber and QDR cleaning.

In view of the above circumstances, it is an object of the present invention to provide a method of manufacturing a semiconductor device which prevents short circuits between wirings due to a tungsten residue and improves the yield.

[0007]

A method of manufacturing a semiconductor device for achieving the above object comprises a step of forming a contact hole and / or a via hole in a semiconductor substrate, and burying tungsten in the contact hole and / or the via hole. The method is characterized by including a step, a step of cleaning the semiconductor substrate in which the tungsten is embedded with a hydrogen peroxide solution, and a step of forming wiring after the cleaning step.

Here, the concentration of hydrogen peroxide solution is 5% or more 3
It is preferably 5% or less and the cleaning time is 2 minutes or more and 4 minutes or less. Furthermore, it is preferable to use ultrasonic waves together when cleaning with hydrogen peroxide solution.

[0009]

According to the method of manufacturing a semiconductor device of the present invention, the semiconductor device having tungsten buried in the contact holes and the like is washed with hydrogen peroxide solution. This hydrogen peroxide water gently etches tungsten, and is isotropic etching unlike dry etching. Therefore, tungsten existing between the periphery of the foreign matter and the adhesion layer or in the step portion of the adhesion layer caused by the foreign matter is present. The residue can be removed. As a result, the tungsten residue that causes a short circuit between the adjacent wirings can be removed, so that the yield is improved.

When the concentration of the hydrogen peroxide solution is less than 5%, the removal rate of tungsten becomes very slow and it takes a long time for cleaning, while the concentration of the hydrogen peroxide solution is 35%.
If it exceeds the range, the removal rate of tungsten becomes too fast, so that the tungsten in the contact hole may also be removed. Therefore, the concentration of the hydrogen peroxide solution is preferably 5% or more and 35% or less. Further, if the cleaning time is less than 2 minutes, the tungsten residue cannot be sufficiently removed, while if it exceeds 4 minutes, the effect of removing the tungsten residue is the same. Therefore, the cleaning time is preferably 2 minutes or more and 4 minutes or less.

Further, when ultrasonic waves are used together when cleaning with a hydrogen peroxide solution, the tungsten residue is well removed and the yield is further improved.

[0012]

EXAMPLE An example of a method of manufacturing a semiconductor device according to the present invention will be described below. FIG. 1 is a cross-sectional view showing a process when an evaluation experiment is performed by a simple process using a wiring short circuit check test pattern. First, as shown in FIG. 1A, a base oxide film 42 is formed on a wafer 40 by a CVD method.
Formed 6000 angstroms. Next, FIG.
As shown in (b), a Ti layer 44 of 500 angstrom and a TiN layer 46 of Ti and TiN laminated films, which will be a barrier layer and an adhesion layer of tungsten, are sequentially formed by a continuous sputtering method.
Of 1000 angstrom was formed. Next, 1 μm of tungsten is deposited on the Ti layer 44 and the TiN layer 46 by the CVD method.
m, and a tungsten layer 48 was formed as shown in FIG. WF ₆ , SiH ₄ , as source gas,
It was performed at a substrate temperature of 400 ° C. using a mixed gas of H ₂ . Next, as shown in FIG. 1D, the tungsten layer 48 was etched back by dry etching using SF ₆ gas. After the etching back was completed, cleaning with hydrogen peroxide was performed. In this embodiment, a plurality of wafers are used, and the entire wafer is immersed in hydrogen peroxide solution having a concentration of 30% and a temperature of 24 ° C. for 60 seconds, 120 seconds, 180 seconds, 240 seconds, and 60 seconds, respectively.
It was immersed for 0 seconds. For comparison, a wafer was also prototyped that was not washed with hydrogen peroxide and was only washed with a scrubber. Next, an Al alloy as a wiring material is sputtered
After depositing 00 angstrom, a wiring 50 was formed by photolithography and dry etching as shown in FIG.

Table 1 shows the measurement results of the yield of the short circuit of the wiring of 1.0 μm line and space and the increase / decrease of foreign matter before and after cleaning. This measurement result is an average value of 5 wafers that have been washed with hydrogen peroxide for 180 seconds, and the size and number of foreign particles are inspected by a laser surface inspection device to be 0.5 μm.
The above foreign substances were counted. As shown in Table 1, the number of foreign matters hardly changed in the scrubber cleaning, whereas the number of foreign matters decreased in the hydrogen peroxide solution cleaning. As a result, the wiring short-circuit yield was improved by 20% or more.

[0014]

[Table 1] ─────────────────────────── Hydrogen peroxide water cleaning Scrubber cleaning ───────────── ─────────────── Wiring short 82.1% 61.7% Yield Foreign matter before and after cleaning 215-33 Number change ────────────── ────────────── Figure 2 shows the relationship between the yield of short circuit of 1.0 μmL & S wiring and the cleaning time.

As shown in FIG. 2, when the cleaning time exceeds 2 minutes, the yield of short circuit of the wiring becomes almost constant.

[0016]

As described above, according to the method of manufacturing a semiconductor device of the present invention, after the tungsten is buried in the contact and the via hole, the semiconductor device is washed with hydrogen peroxide solution before the wiring is formed. Is sufficiently removed, the short circuit of the wiring can be reduced, and the yield is greatly improved.

[Brief description of drawings]

1A and 1B show a wiring short-circuit check test pattern in order to show an effect of a method for manufacturing a semiconductor device of the present invention.
It is sectional drawing which shows the process at the time of performing an evaluation experiment by a simple process.

FIG. 2 is a graph showing a relationship between a yield of a short circuit of a wiring and a cleaning time according to an embodiment of a method for manufacturing a semiconductor device of the present invention.

[Fig. 3] Tungsten is buried in a contact hole,
It is sectional drawing which shows the conventional method of forming wiring after that.

FIG. 4 is a cross-sectional view showing a foreign substance existing on an adhesion layer.

[Explanation of symbols]

 40 Wafer 42 Base Oxide Film 44 Ti Layer 46 TiN Layer 48 Tungsten Layer 50 Wiring

Claims (2)

[Claims] 1. A step of forming a contact hole and / or a via hole in a semiconductor substrate, a step of embedding tungsten in the contact hole and / or the via hole, and a step of cleaning the semiconductor substrate in which the tungsten is embedded with hydrogen peroxide solution. And a step of forming wiring after the cleaning step, the method of manufacturing a semiconductor device. 2. The hydrogen peroxide solution has a concentration of 5% or more and 35% or more.
The method of manufacturing a semiconductor device according to claim 1, wherein the cleaning is performed for 2 minutes or more and 4 minutes or less.