JPH0541379A - Film forming apparatus - Google Patents

Abstract

PURPOSE:To form, at high throughput, Al laminated wiring which is composed of a laminated film by a barrier metal and by an Al alloy. CONSTITUTION:A film forming apparatus is provided with the following: a first chamber 1 wherein a barrier metal film is formed on a semiconductor substrate 4; a second chamber 2 wherein the barrier metal film is exposed to an atmosphere containing oxygen and its film quality is stabilized; and a third chamber 3 wherein an Al alloy film is formed on the barrier metal film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film forming technique, and more particularly to a technique for forming a laminated film of a barrier metal film, which is a wiring material of an LSI, and an Al-based conductive film with high throughput.

[0002]

2. Description of the Related Art In order to promote high integration and high speed of LSI, it is indispensable to miniaturize Al wiring together with scaling of elements. However, there is a problem that the miniaturization of the Al wiring increases its current density and causes a decrease in reliability such as disconnection failure due to electromigration or stress migration.

As a measure for improving the migration resistance of the Al wiring, an Al alloy wiring to which Cu, Si or the like is added has been put into practical use, but in recent years, as a more effective countermeasure, the lower layer (or the upper and lower layers) of the Al alloy. TiN, TiW
Al laminated wiring laid with a barrier metal such as the above has come to be used.

This barrier metal is also used for the purpose of suppressing an increase in contact resistance between the semiconductor substrate and the wiring due to precipitation of Si in the Al alloy wiring.

Regarding barrier metals such as TiN and TiW, Press Journal Co., Ltd., December 12, 1990.
"Monthly Semiconductor World 1991.
1 "P173-P174 and the like.

[0006]

The above-mentioned A is formed on a semiconductor substrate.
In order to form the laminated wiring, the barrier metal film and the Al alloy film may be continuously formed using a multi-chamber sputtering apparatus.

However, conventionally, after the barrier metal film is formed, the wafer is once taken out of the apparatus, the barrier metal film is exposed to the atmosphere, and then the wafer is carried into the apparatus again to form an Al alloy film. Various steps were required.

This is because the barrier metal film (particularly the TiN film) deposited by the sputtering method has a stoichiometric excess of Ti, and as it is, the excess Ti diffuses into the Si substrate to improve the characteristics of the device. There is a risk of deterioration, so excessive T
This is because it is necessary to oxidize i in the atmosphere to stabilize the film quality of the barrier metal.

The present invention has been made in view of the above problems, and an object thereof is to provide a technique capable of forming an Al laminated wiring composed of a laminated film of a barrier metal and an Al alloy with high throughput. Especially.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0011]

According to the present invention, there is provided a first chamber for forming a barrier metal film on a semiconductor substrate, and a second chamber for exposing the barrier metal film to an atmosphere containing oxygen to stabilize its film quality. The film forming apparatus includes a chamber and a third chamber for forming an Al-based conductive film on the barrier metal film.

[0012]

According to the above-described means, a complicated step of stabilizing the barrier metal film by taking out the wafer from the apparatus is not required between the barrier metal film forming step and the Al-based conductive film forming step. It is possible to consistently perform film formation, barrier metal film stabilization treatment, and Al-based conductive film formation in the same apparatus.

Further, this makes it possible to prevent contamination by foreign matter when the wafer is taken out of the apparatus.

[0014]

FIG. 1 is a diagram showing the overall structure of a film forming apparatus which is an embodiment of the present invention. This film forming apparatus is provided with three chambers 1, 2 and 3 which are separated from each other, and forms a barrier metal film, a barrier metal film stabilizing process, and an A
It is a sputtering apparatus capable of consistently forming an l-based conductive film.

A semiconductor wafer (substrate) 4 is provided in each of chambers 1, 2 and 3 capable of evacuating the interior to a predetermined degree of vacuum.
A wafer stage 5 for mounting the wafers is installed.

A vacuum load lock chamber 7 equipped with a robot arm 6 is installed in front of the first chamber 1, and the semiconductor wafer 4 accommodated in the wafer cassette 8 is
This vacuum load lock chamber 7, via the robot arm 6,
Then, the sheets are conveyed to the first chamber 1 one by one.

Although not shown, the first chamber 1 described above
Is provided with a sputtering mechanism for forming a barrier metal film on the semiconductor substrate 4.

A vacuum transfer chamber 9 capable of evacuating the interior to a predetermined vacuum degree is installed in the latter stage of the first chamber 1, and the first chamber 1 and the second chamber 2 are They are connected through the vacuum transfer chamber 9. Inside the vacuum transfer chamber 9, a robot arm 6 that transfers the semiconductor wafer 4 that has been processed in the first chamber 1 to the second chamber 2 is installed.

The second chamber 2 is for stabilizing the barrier metal film on the semiconductor substrate 4. Although illustration is omitted, the chamber 2 is provided with an exhaust means for exhausting the inside to a predetermined vacuum degree and a dry air supply means.

Between the second chamber 2 and the third chamber 3, there is provided a vacuum transfer chamber 10 capable of evacuating the inside to a predetermined vacuum degree, and inside the vacuum transfer chamber 10, there is provided a second transfer chamber. A robot arm 6 for transferring the semiconductor wafer 4 which has been processed in the chamber 2 to the third chamber 3 is installed.

Although not shown, the third chamber 3 is provided with a sputtering mechanism for forming an Al-based conductive film on the semiconductor substrate 4.

A vacuum unload lock chamber 11 equipped with a robot arm 6 is installed in the subsequent stage of the third chamber 3, and the semiconductor wafer 4 on which film formation has been completed is transferred via the robot arm 6 to the vacuum unload lock chamber 11. The wafers are transferred to the load lock chamber 11 and then to the wafer cassette 8 one by one.

A gate valve 12 is provided between each of the chambers 1, 2 and 3, the vacuum load lock chamber 7 and the vacuum unload lock chamber 11 for maintaining airtightness in each chamber. ..

In order to perform sputter deposition of a barrier metal film and an Al-based conductive film using the above-mentioned film deposition apparatus, first,
The semiconductor wafers 4 housed in the wafer cassette 8 are sequentially transferred to the vacuum load lock chamber 7 and then the first chamber 1 via the robot arm 6.

FIG. 2 is a sectional view showing a main part of the semiconductor wafer 4. This semiconductor wafer 4 is made of, for example, p ⁻ -type silicon single crystal, and the n-type semiconductor region 2 is formed in the active region formed by opening a part of the silicon oxide film 20.
1 and platinum silicide (PtSi _x ) on top of it
A Schottky barrier diode SBD made of the layer 22 is formed.

Next, the pressure in the first chamber 1 is adjusted to 0.5-0.5.
The barrier metal film 23 is formed on the entire surface of the semiconductor wafer 4 by sputtering by setting it to 100 mTorr (FIG. 3).

This barrier metal film 23 is made of TiN and is connected to the Schottky barrier diode SBD.
This is a barrier layer for preventing Al in the alloy wiring from diffusing into the interface between the semiconductor region 21 and the platinum silicide layer 22.

Next, the semiconductor wafer 4 is transferred to the robot arm 6
Through the vacuum transfer chamber 9 and then to the second chamber 2 where the pressure on the surface of the semiconductor wafer 4 is 10 mT.
The barrier metal film 23 is stabilized by exposing it to dry air of orr for 60 seconds.

The time for exposing the barrier metal film 23 to the dry air depends on the pressure of the dry air, but usually 5 seconds to 5 minutes is sufficient. The pressure of the dry air is set to about 0.5 to 100 m pressure in consideration of the compatibility with the sputtering film formation.

Next, the semiconductor wafer 4 is transferred to the robot arm 6
Through the vacuum transfer chamber 10 and then to the third chamber 3 to increase the pressure in the chamber 3 to 0.5 to 100 mTo.
The Al alloy film 24 is sputter-deposited on the barrier metal film 23 by setting rr (FIG. 4).

The semiconductor wafer 4 on which the Al alloy film 24 has been formed is transferred to the vacuum unload lock chamber 11,
Next, after being accommodated in the wafer cassette 8, it is conveyed to a dry etching apparatus through a photoresist film forming step, where the barrier metal film 23 and the Al alloy film 2 are formed.
By patterning 4, Al alloy wiring is formed.

FIG. 5 shows the result of evaluating the heat resistance of the Schottky barrier diode SBD after forming the Al alloy wiring by its electrical characteristics.

6 and 7 are for comparison. FIG. 6 shows the case where the barrier metal film is not stabilized, and FIG. 7 shows the case where the barrier metal film is stabilized in the atmosphere. That is the case.

The horizontal axis of each figure represents the heat treatment time at 450 ° C., and the vertical axis represents the Vf value and Vr value, which are the electrical characteristics of the Schottky barrier diode SBD. Here, Vf is a bias voltage (forward voltage) applied to the Schottky barrier diode SBD when a predetermined forward current is obtained, and Vr is a bias voltage applied when a predetermined reverse current is obtained. (Reverse voltage).

As is apparent from FIG. 5, the pressure is 10 mTo.
In the present example in which the barrier metal film was stabilized by exposing it to rr dry air for 60 seconds, the Schottky barrier diode SBD did not deteriorate even after heat treatment at 450 ° C. for 10 hours.

On the other hand, as is apparent from FIG. 6, when the barrier metal film is not stabilized, the Schottky barrier diode SBD deteriorates by heat treatment at 450 ° C. for 5 hours.

Further, as is clear from a comparison between FIG. 5 and FIG. 7, the heat resistance of the Schottky barrier diode SBD which has been subjected to the stabilization treatment of the present embodiment shows that the barrier metal film is stabilized in the atmosphere. It was no better than the heat resistance of.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the embodiments and various modifications can be made without departing from the scope of the invention. Needless to say.

Although TiN is used as the barrier metal in the above-mentioned embodiment, it can be applied to the case where TiW is used.

It can also be applied to the case of forming an Al laminated wiring having a three-layer structure in which barrier metals are laminated on and under an Al alloy.

[0041]

The effects obtained by the typical ones of the inventions disclosed in this application will be briefly described as follows.
It is as follows.

(1) According to the present invention, it is possible to consistently perform the barrier metal film deposition, the barrier metal film stabilization treatment, and the Al-based conductive film deposition in the same apparatus. The Al laminated wiring can be formed with high throughput.

(2) According to the present invention, when the barrier metal film is stabilized, the semiconductor wafer is not taken out of the apparatus as in the conventional case. Therefore, contamination of the semiconductor wafer by foreign matter can be prevented. it can.

[Brief description of drawings]

FIG. 1 is a diagram showing an overall configuration of a film forming apparatus that is an embodiment of the present invention.

FIG. 2 is a cross-sectional view of an essential part of a semiconductor substrate for explaining a film forming method of this example.

FIG. 3 is a cross-sectional view of an essential part of a semiconductor substrate for explaining a film forming method of this example.

FIG. 4 is a cross-sectional view of an essential part of a semiconductor substrate for explaining a film forming method of this example.

FIG. 5 is a graph showing the heat resistance of the Schottky barrier diode obtained by the film forming method of this example in terms of its electrical characteristics.

FIG. 6 is a graph showing the heat resistance of a Schottky barrier diode obtained by a film forming method in which the barrier metal film is not stabilized, in terms of its electrical characteristics.

FIG. 7 is a graph showing the heat resistance of a Schottky barrier diode obtained by a conventional film forming method in terms of its electrical characteristics.

[Explanation of symbols]

 1 chamber 2 chamber 3 chamber 4 semiconductor wafer (substrate) 5 wafer stage 6 robot arm 7 vacuum load lock chamber 8 wafer cassette 9 vacuum transfer chamber 10 vacuum transfer chamber 11 vacuum unload lock chamber 12 gate valve 20 silicon oxide film 21 semiconductor region 22 Platinum silicide layer 23 Barrier metal film 24 Al alloy film SBD Schottky barrier diode

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shuji Ogishi, 2326 Imai, Ome, Tokyo, Hitachi Device Development Center (72) Inventor, Daisuke Okada 2326, Imai, Ome, Tokyo Hitachi, Ltd. Device Development (72) Inventor Yuji Tanitsuda 2326 Imai, Ome, Tokyo Metropolitan area Device Development Center, Hitachi, Ltd. (72) Inventor Shinichi Kabaya 2326 Imai, Ome city, Tokyo Hitachi, Ltd. Device Development center

Claims (3)

[Claims] 1. A first chamber for forming a barrier metal film on a substrate, a second chamber for exposing the barrier metal film to an atmosphere containing oxygen to stabilize its film quality, and the barrier metal. A film forming apparatus comprising: a third chamber for forming an Al-based conductive film on the film. 2. The atmosphere containing oxygen has a pressure of 0.
5. It is 5-100 mTorr, It is characterized by the above-mentioned.
The film forming apparatus described. 3. The film forming apparatus according to claim 1, wherein the barrier metal film is a TiN film.