JPH08204004A - Manufacturing method for semiconductor device - Google Patents

Abstract

PURPOSE: To easily form a fine multilayer interconnection with high reliability by, at high temperature reflow after forming a metal thin film, applying ultrasonic vibration while a silicon substrate is heated, so that a part of the metal thin film is buried in a contact hole. CONSTITUTION: An inter-layer insulation film 3 is formed on the surface of a silicon substrate 1, and on the specified area of the inter-layer insulating film 3, a contact hole 4 is formed. With the inter-layer insulation film 3 and the contact hole 4 covered, a metal thin film 8 is formed. The petal thin film 8 consists of aluminum or alloy, made of aluminum, copper or germanium, etc. Using, for example, an aluminum metal film 8, after its film-forming, in high vacuum, a silicon substrate 1 is heated and applied with ultrasonic vibration 9 at the same time, so that a part of the aluminum metal film 8 is buried in the contact hole 4. By this, at high temperature reflow, thrusting of an aluminum metal through to a diffusion layer, and formation of rough surface of wiring, etc., are prevented.

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 a method for forming a wiring including burying a conductive material in a contact hole.

[0002]

2. Description of the Related Art Miniaturization and densification of the structure of semiconductor devices are still vigorously promoted. Regarding miniaturization, at present, a semiconductor element formed with a dimension of 0.15 μm to 0.2 μm is used, and development and study of a 1 Gbit DRAM or the like based on this dimension is being studied. Regarding the densification, a method of making the semiconductor element three-dimensional as well as a planar densification by miniaturization have been studied, and some of them have already been put to practical use. In fact, the three-dimensionalization of this semiconductor element has been practically applied to a passive element such as a capacitor among semiconductor elements, together with a multilayer structure of electrode wiring or a multi-layered structure of diffusion layers. Is embodied. At present, this three-dimensionalization is being studied at the development level even for active elements such as transistors.

As described above, miniaturization and three-dimensionalization are the most effective methods for achieving high performance or multi-functionalization of semiconductor devices by high integration, high speed, etc., and are essential for future manufacturing of semiconductor devices. Has become.

On the other hand, due to such miniaturization and three-dimensionalization, the flatness of the semiconductor element is deteriorated, and it is becoming more and more difficult to form the above-mentioned multilayer wiring despite the necessity. This is because the three-dimensional structure increases the vertical dimension more than the lateral dimension of the semiconductor element, and the step difference between where the semiconductor element is present and where it is not is increased. For this,
The film thickness of the interlayer insulating film between the diffusion layer on the surface of the semiconductor substrate and the wiring or between the multilayer wiring increases, and the aspect ratio of the contact hole formed in the interlayer insulating film increases. Further, it tends to be difficult to fill the contact hole with metal.
And this tendency is more remarkable in a finer semiconductor device.

Regarding the method of connecting between the diffusion layer and the wiring or between the multilayer wiring and the method of filling the contact hole with the conductive material, aluminum metal is deposited by the sputtering method, and then heat treatment is performed in a high vacuum (hereinafter The method of forming an aluminum metal film is called the technique for burying a conductor material in a contact hole and wiring a metal at the same time, and is considered to be the most easily applied technique for mass production for the time being.

A conventional wiring forming method using this high temperature reflow method will be described below. 5A to 5C are schematic cross-sectional views in the order of steps showing the conventional technique. As shown in FIG. 5A, a diffusion layer 42 is formed in a predetermined region of the silicon substrate 41 by ion implantation of impurities and heat treatment. After this, an interlayer insulating film 43 covering the entire surface of the silicon substrate 41 is formed. This interlayer insulating film 43 is formed by CVD.
Silicon oxide film or BP by (Chemical Vapor Deposition) method
It is performed by forming an SG (silicon oxide containing boron glass and phosphorus glass) film. Then, a contact hole 44 is formed in a predetermined region of the interlayer insulating film 43 by a known photolithography technique and dry etching technique. Here, the contact hole 44 corresponds to the diffusion layer 42 described above.
Formed in the region of.

Next, a silicide layer 45 is formed on the surface of the diffusion layer 42 in the region where the contact hole is formed.
After doing so, the barrier layer 46 is formed. Here, the silicide layer 45 or the barrier layer 46 is formed by a sputtering method of a refractory metal such as titanium or titanium nitride. Next, the aluminum metal film 47 is deposited in another chamber of the sputtering apparatus equipped with the multi-chamber used for forming the silicide layer 45 and the barrier layer 46 described above.

Next, a high temperature reflow process is performed in another chamber of the above-mentioned sputtering apparatus. Here, in this high temperature reflow process, the processing temperature is 500 to 550.
The temperature is set to 0 ° C and the degree of vacuum is set to 10 ^-6 to 10 ^-9 Torr. As shown in FIG. 5B, a part of the aluminum metal film 47 flows into the contact hole 44 by this high temperature reflow, and the contact hole 44 is filled with the aluminum metal. After this, the aluminum metal film 4 is formed by the known photolithography technique and dry etching technique.
7 is processed to form the wiring 48.

As described above, the diffusion layer 42 and the wiring 48 formed on the surface of the silicon substrate 41 form the interlayer insulating film 4
Electrical connection is made through a contact hole provided in the No. 3.
In the above description of the prior art, the formation of the wiring electrically connected to the diffusion layer has been described. Here, when the lower layer wiring and the upper layer wiring, which are multilayer wirings replaced with the diffusion layers, are electrically connected, the same formation is performed.

[0010]

In the above-described conventional wiring forming method, a void 49 may partially remain in the contact hole 44 in which the aluminum metal film is buried as shown in FIG. Furthermore, penetration through the diffusion layer of aluminum metal during high temperature reflow (hereinafter referred to as aluminum spike)
May occur, or wiring irregularities 50 on the surface of the wiring 48 may be formed. These are because in the conventional method, it is necessary to raise the temperature of high temperature reflow, and as a result, the barrier effect of the barrier layer 46 against aluminum or silicon atoms is lowered and the surface of the aluminum metal film 47 is likely to occur after high temperature reflow. Is.

The void 4 generated by the formation of such a wiring
9. The aluminum spikes or the wiring irregularities 50 make it difficult to deal with the miniaturization of the semiconductor element or the multilayer wiring due to the higher integration or higher density of the semiconductor device. In particular, the reliability of the wiring formed of the aluminum metal film is significantly reduced.

An object of the present invention is to solve the above problems and facilitate the formation of highly reliable fine multilayer wiring.

[0013]

Therefore, a method of manufacturing a semiconductor device according to the present invention comprises a step of forming a contact hole in a predetermined region of an interlayer insulating film formed on the surface of a semiconductor substrate, and the interlayer insulating film. And a step of coating the contact hole to form a metal thin film, and after the metal thin film is formed, the semiconductor substrate is heated in a high vacuum and at the same time ultrasonic vibration is applied to the semiconductor substrate to form the contact. Burying a part of the metal thin film in the hole.

Here, in the manufacture of this semiconductor device,
Ultrasonic vibration of the semiconductor substrate is applied from the back surface of the semiconductor substrate, and the vibration direction of the ultrasonic vibration is set to be a direction perpendicular to the front surface of the semiconductor substrate.

Alternatively, in the step of forming the metal thin film, the metal thin film is deposited by a sputtering method while ultrasonically vibrating the semiconductor substrate in a direction parallel to the surface of the semiconductor substrate, and then the above-described series of steps is performed. That is, the step of burying a part of the metal thin film in the contact hole is performed.

The metal thin film is made of aluminum or an alloy of aluminum and copper or germanium or the like.

[0017]

Next, the present invention will be described with reference to the drawings. 1A to 1D are cross-sectional views showing a manufacturing method in the order of steps in an embodiment of the present invention. As shown in FIG. 1A, the diffusion layer 2 is formed in a predetermined region of the silicon substrate 1. After doing so, the interlayer insulating film 3 is formed. Here, this interlayer insulating film 3 is a silicon oxide film or a BPSG film with a film thickness of about 500 nm deposited by the CVD method. Next, the contact hole 4 is formed by a known photolithography technique and dry etching technique. The diameter of the contact hole 4 is set to 0.2 μm to 0.3 μm.

Next, a titanium silicide layer 5 is formed on the surface of the diffusion layer 2 in the region where the contact hole 4 is formed.
The titanium silicide layer 5 is formed by a collimated sputtering method or the like. After this, the titanium nitride layer 6 having a film thickness of 10 nm to 50 nm is formed by the CVD method. Here, when forming the titanium nitride layer 6 by this CVD method, TiCl ₄ or a mixed gas of alkyl Ti and NH ₃ or N ₂ H ₂ is used as a reaction gas,
N ₂ or H ₂ gas is used as the atmosphere gas.
The film forming temperature is set at 350 to 600 ° C. After forming this titanium nitride layer 6, a titanium layer 7 having a film thickness of 10 nm to 20 nm is formed so as to cover this layer. The titanium layer 7 is deposited by a CVD method using a mixed gas of TiCl ₄ and H ₂ or a plasma excited CVD method. When the diameter of the contact hole is large, the titanium layer 7 can be deposited so as to cover the titanium nitride layer 6 even if the sputtering method is used.

Next, as shown in FIG. 1B, an aluminum metal film 8 is formed on the titanium layer 7 described above. The thickness of the aluminum metal film 8 is set to about 500 nm and is formed by the sputtering method.

Next, the aluminum metal film 8 is subjected to a high temperature reflow process using a processing apparatus described later. This processing is performed in another chamber in the above-described aluminum metal film sputtering apparatus. Here, in this high temperature reflow process, the processing temperature is set to 350 to 450 ° C. and the degree of vacuum is set to 10 ⁻⁶ to 10 ⁻⁹ Torr. Then, during the high temperature reflow, the ultrasonic vibration 9 shown in FIG. 1C is applied to the silicon substrate 1. Thus, FIG. 1 (c)
As shown in FIG.
And the contact hole 4 is completely filled with the aluminum metal film. After this, the aluminum metal film 8 is processed by the known photolithography technique and dry etching technique to form the wiring 10.

Next, the high temperature reflow processing apparatus of the present invention and the processing method thereof will be described in detail with reference to FIG. FIG. 2 is a sectional view of this processing apparatus. As shown in FIG. 2, the substrate holding plate 22 is provided so as to adhere to the soaking plate 21, and the silicon substrate 23 is placed on the substrate holding plate 22. Then, the silicon substrate 23 is fixed by suction with a vacuum chuck, and the inside of the high vacuum chamber 24 filled with Ar gas is evacuated through the exhaust port 25. Here, the high vacuum chamber 24 is generated by this vacuum exhaust.
The degree of vacuum inside is set and maintained at 10 ⁻⁶ to 10 ⁻⁹ Torr.

Further, the soaking plate 21 is heated by the heating source 26, and the silicon substrate 23 is held at a predetermined temperature through the substrate holding plate 22. Here, a heater or a heating lamp is used as the heating source 26, and the temperature of the silicon substrate 23 is maintained at a set temperature of 350 to 500 ° C.

Further, ultrasonic waves are generated by the ultrasonic oscillator 27 and transmitted to the holder 29 through the transmission shaft 28, and ultrasonic vibration is applied to the silicon substrate 23. Here, the frequency of this ultrasonic vibration is set to 1 MHz to 10 MHz, and its amplitude is set to about 1 μm. The vibration direction of this ultrasonic vibration is set to be the vertical direction in the cross-sectional view of the processing apparatus shown in FIG. 2, that is, the direction perpendicular to the surface of the silicon substrate 23.

In this way, the above-mentioned high temperature reflow of the aluminum metal film is performed by the high temperature reflow processing apparatus having a mechanism of heating the silicon substrate in a high vacuum and vibrating ultrasonically. By this method, the temperature of high temperature reflow is lowered. For example, when the temperature is 550 ° C. in the conventional technique, the temperature required by the method of the present invention is lowered to 350 to 400 ° C. By lowering the processing temperature in this way, deterioration of the diffusion layer due to aluminum spikes or the like, or increase in electrical resistance in the contact hole can be prevented. Furthermore, the processing time for high temperature reflow is also shortened. For example, with the conventional technique, the processing time of 2 minutes is about 1 minute.

In the above embodiments, the case where the aluminum metal film 8 is formed by the sputtering method has been described, but it is noted that the same effect can be obtained even if the aluminum metal film 8 is formed by the aluminum CVD method. I'll do it.

Next, a second embodiment of the present invention will be described with reference to FIGS.
It will be described based on. Here, FIG. 3 is a cross-sectional view showing the manufacturing method of the second embodiment of the present invention in the order of steps, and FIG. 4 is a cross-sectional view of the continuous film forming apparatus used in the manufacturing method of the second embodiment.

First, as described in the first embodiment, the diffusion layer 2 is formed in a predetermined region of the silicon substrate 1. Then, the interlayer insulating film 3 is formed. Here, this interlayer insulating film 3 has a film thickness of 5 deposited by the CVD method as in the first embodiment.
It is a silicon oxide film or a BPSG film having a thickness of about 00 nm. Next, the contact hole 4 is formed by a known photolithography technique and dry etching technique. The diameter of the contact hole 4 is set to 0.2 μm.

Next, a titanium silicide layer 5 is formed on the surface of the diffusion layer 2 in the region where the contact hole is formed. The titanium silicide layer 5 is formed by a collimated sputtering method or the like. After this, the titanium nitride layer 6 having a thickness of about 20 nm is formed by the CVD method. After forming the titanium nitride layer 6, a titanium layer 7 having a thickness of about 10 nm is formed so as to cover this layer. here,
The titanium layer 7 is deposited by a CVD method using a mixed gas of TiCl ₄ and H ₂ or a plasma excited CVD method.

Next, aluminum metal is deposited by sputtering. In this film formation, as shown in FIG. 3A, ultrasonic vibration 9a is applied to the silicon substrate 1 during sputtering of aluminum metal. Here, the vibration frequency and amplitude of this ultrasonic vibration 9a are set to 5 MHz and 2 μm, respectively, and the direction of the vibration is set to be parallel to the surface of the silicon substrate. By doing so, the ultrasonic vibration described above is applied to the attached aluminum atoms 11 that have reached the titanium layer 7 by sputtering as shown in FIG. Then, the easiness of movement of the surface of the attached aluminum atoms 11 is increased, and the step coverage of the aluminum metal film is improved. The aluminum atoms 11a that do not reach the titanium layer 7 go straight without being disturbed by the atmospheric gas (mainly Ar gas).

By doing so, the aluminum metal film 8 is deposited on the titanium layer 7 with good coverage as shown in FIG. 3 (b). Here, the film thickness of the aluminum metal film 8 is 300 n.
It is set to about m.

Next, the aluminum metal film 8 is subjected to a high temperature reflow treatment. This process is performed in the same high vacuum chamber as the above-mentioned aluminum metal film sputtering apparatus. Here, in this high temperature reflow process, the processing temperature is 350.
It is set to ~ 400 ° C and the degree of vacuum is 10 ^-6 to 10 ^-9 To.
It is set to rr. Then, during this high temperature reflow, the ultrasonic vibration 9 is applied to the silicon substrate 1 as described in the first embodiment. Thus, as shown in FIG. 1C, part of the aluminum metal film 8 flows into the contact hole 4, and the contact hole 4 is completely filled with the aluminum metal film. After this, the aluminum metal film 8 is processed by the known photolithography technique and dry etching technique to form the wiring 10.

Next, the film forming continuous processing apparatus of the present invention and the processing method thereof will be described in detail with reference to FIG.
As shown in FIG. 4, the substrate electrode 22a is provided so as to adhere to the soaking plate 21, and the silicon substrate 23 is placed on the substrate electrode 22a. And this silicon substrate 23
Is fixed by suction with a vacuum chuck, and the high vacuum chamber 24 filled with Ar gas is evacuated through an exhaust port 25. Here, the degree of vacuum in the high vacuum chamber 24 is maintained at 10 ^-9 Torr or higher by this vacuum exhaust.

Next, Ar gas is introduced into the high vacuum chamber 24 through the inlet 31. And the heating source 26
Thus, the soaking plate 21 is heated, and the silicon substrate 23 is set to a predetermined temperature through the substrate electrode 22a. here,
As the heating source 26, a heating lamp that is capable of rapid heating and rapid cooling is used, and the temperature of the silicon substrate 23 is maintained at a set temperature of 150 ° C.

Further, ultrasonic waves are generated by the ultrasonic oscillator 27 and transmitted to the holder 29 through the transmission shaft 28, and ultrasonic vibration is applied to the silicon substrate 23. Here, the frequency of this ultrasonic vibration is set to 1 MHz to 10 MHz, and its amplitude is set to about 1 μm. The vibration direction of this ultrasonic vibration is set to the left and right directions in the sectional view of the processing apparatus shown in FIG. 4, that is, the direction parallel to the surface of the silicon substrate 23.

In this way, the substrate electrode 22a is set to the ground potential and a high negative voltage is applied to the cathode 32. Then, the aluminum target 33 is sputtered with Ar ions, and the aluminum metal sputtering described with reference to FIG. 3A is performed.

The high temperature reflow process in the second embodiment is continuously performed after the aluminum metal film is formed by the above-described aluminum metal sputtering method in the film forming continuous processing apparatus. In this case, the method is exactly the same as that described in the first embodiment. In this case, the power supply for sputtering is stopped and no voltage is applied to the substrate electrode 22a and the cathode 32.

As described above, in the second embodiment, the deposition process of the aluminum metal film and the high-temperature reflow are continuously performed, whereby the film formation processing time of the aluminum metal film used for the wiring is significantly shortened. .

In the above embodiments, the case where the metal thin film is made of aluminum has been described, but the same effect can be obtained even when the metal thin film is made of an alloy of aluminum and copper or an alloy of aluminum and germanium. Touch.

Further, in the above embodiments, the formation of the wiring electrically connected to the diffusion layer was mainly described, but the same effect can be obtained when the wiring of the lower layer and the wiring of the upper layer in the multilayer wiring are connected. Also mention.

[0040]

As described above, according to the method of manufacturing a semiconductor device of the present invention, ultrasonic vibration is applied while heating the silicon substrate during high temperature reflow after the metal thin film is formed. Will be completely embedded in the metal thin film. Therefore, no void is generated in the contact hole in which the metal thin film is embedded. Furthermore, the temperature of this high-temperature reflow is 150 to 150 times that of the conventional technique.
It can be lowered by about 200 ℃. Therefore, it is possible to prevent the penetration of aluminum metal into the diffusion layer during the high temperature reflow, and the formation of the wiring irregularities on the surface of the wiring.
This is because the decrease in temperature secures the barrier effect of the barrier layer against aluminum or silicon atoms and suppresses local melting of aluminum.

As described above, the present invention facilitates the formation of highly reliable fine multi-layered wiring and promotes high integration or high density of semiconductor devices.

[Brief description of drawings]

1A to 1D are cross-sectional views in order of a process, illustrating a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of a high temperature reflow processing apparatus used in the first embodiment of the present invention.

3A to 3D are sectional views in order of the steps, for explaining the second embodiment of the present invention.

FIG. 4 is a cross-sectional view of a film forming continuous processing apparatus used in a second embodiment of the present invention.

5A to 5C are cross-sectional views in order of processes, illustrating a conventional technique.

[Explanation of symbols]

 1,23,41 Silicon substrate 2,42 Diffusion layer 3,43 Interlayer insulating film 4,44 Contact hole 5 Titanium silicide layer 6 Titanium nitride layer 7 Titanium layer 8,47 Aluminum metal film 9,9a Ultrasonic vibration 10,48 Wiring 11 Adhered Aluminum Atoms 11a Aluminum Atoms 21 Soaking Plate 22 Substrate Holding Plate 22a Substrate Electrode 24 High Vacuum Chamber 25 Exhaust Port 26 Heating Source 27 Ultrasonic Oscillator 28 Transmission Shaft 29 Holder 31 Inlet 32 Cathode 33 Target 45 Silicide Layer 46 Barrier Layer 49 void 50 uneven wiring

Claims (4)

[Claims] 1. A step of forming a contact hole in a predetermined region of an interlayer insulating film formed on a surface of a semiconductor substrate, and a step of coating the interlayer insulating film and the contact hole to form a metal thin film. After forming the metal thin film, heating the semiconductor substrate in a high vacuum and applying ultrasonic vibration to the semiconductor substrate at the same time to embed a part of the metal thin film in the contact hole. And a method for manufacturing a semiconductor device. 2. The ultrasonic vibration of the semiconductor substrate is applied from the back surface of the semiconductor substrate, and the vibration direction of the ultrasonic vibration is perpendicular to the surface of the semiconductor substrate. A method for manufacturing a semiconductor device as described above. 3. The step of depositing the metal thin film, wherein the metal thin film is deposited by a sputtering method while ultrasonically vibrating the semiconductor substrate in a direction parallel to the surface of the semiconductor substrate. Item 2. A method of manufacturing a semiconductor device according to item 1. 4. The method of manufacturing a semiconductor device according to claim 1, wherein the metal thin film is made of aluminum or an alloy of aluminum and copper or germanium.