JP2000349086A - Manufacture and apparatus for semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus and a method for manufacturing a semiconductor device capable of reliably subjecting a Cu film of a wiring material of a semiconductor device to a predetermined heat treatment without changing a laser heat treatment apparatus, even if the Cu film is thick. SOLUTION: A wiring trench 12 is formed on an insulating film 11 on a semiconductor substrate 10 and then a Cu film 13 is formed. Then, the uppermost surface of the Cu film 13 is oxidized to reduce its refractive index for laser light to increase the efficiency of energy of the applied laser light. Thereafter, the laser light is applied to the Cu film 13 to melt it, whereby the Cu 13 is buried in the wiring trench 13.

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 and a technology of a manufacturing apparatus therefor, and more particularly, to a technology of forming a metal as an electrode material in a fine contact hole or a via hole and a metal as an electrode material. The present invention relates to a technique for performing heat treatment.

[0002]

2. Description of the Related Art Conventionally, an aluminum alloy has often been mainly used as a wiring material for a semiconductor element. However, in recent years, the wiring material of aluminum alloy has a concern that the operating speed may be reduced due to an increase in current density accompanying the miniaturization of wiring, particularly for a semiconductor element which requires formation of an ultra-fine pattern or ultra-high-speed operation. I have. For this reason, it has been attempted to use a wiring made of Cu or the like having high resistance to electromigration and having a lower electric resistance than aluminum. However, when forming wiring with Cu, there is no compound having a low vapor pressure and it is difficult to perform dry etching, so that a method of manufacturing with wiring having a buried structure is often used.

[0003] There are roughly two methods of fabricating a wiring having a buried structure. The first method is to form a Cu film on a patterned insulating film by a sputtering method and irradiate the film with an excimer laser beam. This is a laser melt method in which a film is melted and embedded in a wiring groove. FIGS. 8A to 8D show a process flow of this laser melt method.

[0004] First, as shown in FIG. 8A, a wiring groove 42 is formed in an insulating film 41 formed on a silicon substrate (wafer) 40, for example. Next, FIG.
As shown in FIG. 3, a Cu film 43 having a thickness of 0.3 μm is formed on the insulating film 41 by a sputtering method. Next, FIG.
As shown in the figure, the Xe-Cl excimer laser was
By irradiating and melting a part of the
Embed At this time, the melting point of Cu is 1083 ° C., and the laser irradiation temperature is 1100 ° C. or higher and 2500 ° C.

[0005] Next, as shown in FIG.
(Chemical mechanical polishing) by Cu wiring 43, 4 in wiring groove
3a, and the Cu film 43a on the other insulating film is polished. Remove.

[0006] The second method of forming a wiring having a buried structure is a plating method. First, a Cu film is formed on a patterned insulating substrate by a plating method. By plating, Cu can be buried in holes and grooves at the same time by forming a film. However, the film obtained by the plating method is the S in the plating solution.
And additives are contained in the film, and the crystal grain size is 0.1.
Since it is as small as about 2 μm, it is not enough for wiring. Therefore, some heat treatment (lamp annealing, electric furnace annealing, laser annealing) is performed to grow crystal grains to make them suitable for wiring.

[0007] In any of these methods,
When heating Cu by the energy of laser irradiation,
A relationship is established in which the energy of laser irradiation is proportional to the thickness of the Cu film.

[0008]

However, when heating Cu by laser irradiation as described above, FIG.
As shown in (2), in the melting region (1083 ° C. to 2570 ° C.), the energy of the laser irradiation is proportional to the thickness of the Cu film. Heat treatment (heating of Cu) cannot be performed.

That is, in order to increase the energy of laser irradiation, (a) a method of increasing the laser output from the laser oscillator, narrowing down the laser light, and reducing the laser light irradiation area on the Cu film. (B) Techniques such as a method of reducing the loss of a transmission optical system for transmitting laser light from the oscillator to the surface of the Cu film are required. In general, to increase the laser output from the laser oscillator, Since it is necessary to increase the size, the area occupied by the entire laser heat treatment apparatus is increased, and the running cost of the laser apparatus is undesirably increased.

[0010] Further, the laser irradiation area can be reduced by increasing the reduction magnification of the imaging lens of the laser heat treatment apparatus. However, the tact time for processing wafers per unit quantity is increased and the production efficiency is reduced. Is not preferred for reasons. Also, it is technically difficult to reduce the loss that occurs during optical transmission of the transmission optical system in the laser heat treatment apparatus, exceeding the current level.

The present invention has been made based on these circumstances. Even if the thickness of a Cu film, which is a wiring material of a semiconductor device, becomes large, the laser heat treatment apparatus can be changed without changing the portion.
It is an object of the present invention to provide a method of manufacturing a semiconductor element and a manufacturing apparatus for the semiconductor element, which can reliably perform a predetermined heat treatment on a Cu film.

[0012]

According to the first aspect of the present invention, after forming a wiring groove in an insulating film on a semiconductor substrate, a Cu film is formed on the insulating film. A method for manufacturing a semiconductor device, comprising irradiating a laser beam and thereafter performing a flattening process, wherein the surface of the Cu film is oxidized in advance before the Cu film is irradiated with the laser beam. It is a manufacturing method of.

According to the second aspect of the present invention,
The oxidation treatment on the surface of the Cu film is performed by subjecting the semiconductor substrate to 2
This is a method for manufacturing a semiconductor device, characterized in that lamp annealing or heating in an electric furnace is performed at a temperature of not less than 00 ° C. and not more than 500 ° C., and the resultant is exposed to an oxygen gas atmosphere.

According to the third aspect of the present invention,
A method of manufacturing a semiconductor device, characterized in that the formation of a Cu film on the insulating film is performed by sputtering Cu.

According to a fourth aspect of the present invention,
A method of manufacturing a semiconductor device, characterized in that formation of a Cu film on the insulating film is performed by plating.

According to the fifth aspect of the present invention,
A method of manufacturing a semiconductor device, characterized in that Cu is buried in a wiring groove by irradiating the Cu film with the laser beam to melt the Cu film.

Further, according to the means of the present invention,
A method for manufacturing a semiconductor element, comprising: forming a Cu film in a hole or a groove formed on the semiconductor substrate in a state suitable for buried wiring by laser annealing by irradiating the Cu film with laser light. It is.

According to the means of the invention of claim 7,
After a wiring groove is formed in an insulating film on a semiconductor substrate, a Cu film is formed on the insulating film, and the Cu film is irradiated with laser light in a semiconductor device manufacturing apparatus. Laser irradiation chamber to be
An apparatus for manufacturing a semiconductor device, comprising: a Cu film oxidation forming chamber for performing an oxidation treatment on a surface of a u film.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. 1A to 1E show a sectional structure of a wafer in a manufacturing process according to a method for manufacturing a semiconductor device of the present invention.

First, as shown in FIG. 1A, for example, a wiring groove 12 (having a width of, for example, about 0.6 μm and a depth of, for example, about 0.2 μm) is formed in an insulating film 11 formed on a silicon substrate (wafer) 10. 3 μm, with a total extension of, for example, about 50 cm).
Next, as shown in FIG. 1B, a Cu film 13 having a thickness of 0.3 μm is formed on the insulating film 11 by a sputtering method.

Next, as shown in FIG. 1C, Xe-C
The excimer laser is irradiated to a part of the Cu film 13 to melt it.
By doing so, Cu is embedded in the wiring groove. This laser
During the irradiation process, the laser beam irradiation temperature is the melting point of Cu
(1083 ° C), which is higher than about 1100 ° C.
Of reducing gas to oxidizing gas in natural atmosphere
Laser irradiation is performed while controlling the partial pressure ratio to a predetermined value. An example
For example, H as an oxidizing gas ₂When using O, reducing gas
H₂And H₂O partial pressure is about 102Pa
H in a vacuum₂Introduced so that the partial pressure of
Keep it.

Next, as shown in FIG.
By (chemical mechanical polishing), the Cu wiring 13 in the wiring groove is left, and the Cu film 13 on the other insulating film is polished and removed.

Next, as shown in FIG.
Thereby, an interlayer insulating film 14 is formed on the entire surface of the substrate. this
At this time, the temperature of the CVD process is about 350 ° C. and the process atmosphere
The partial pressure ratio of reducing gas to oxidizing gas
The CVD process is performed in a state where it is controlled to a constant value. For example, oxidation
H as a neutral gas₂O, H as reducing gas₂And H
₂O partial pressure is about 10^-1H in a vacuum of Pa₂Partial pressure of
Is about 10^-1Pa and then SiH
₄Gas and O₂By introducing gas, the interlayer insulation
SiO as the film 14₂To form

Thereafter, although not shown, a via contact hole (interlayer connection hole) is opened in the interlayer insulating film,
A second layer Cu wiring is formed thereon, and a passivation film is formed thereon to form a pad.

According to the method of forming a Cu wiring of the above-described embodiment, H ₂ in an atmosphere for heat treatment of Cu is used.
The / H ₂ O partial pressure ratio is appropriately controlled according to the processing temperature. This can prevent the formation of a high-resistance altered layer containing a Cu oxide such as CuO or Cu ₂ O, and can prevent an increase in wiring resistance.

As in the above embodiment, the width is about 0.6 μm, the depth is about 0.3 μm, and the total extension is about 50 cm.
A voltage was applied between both ends of the Cu wiring 13a buried in the wiring groove 12 in the longitudinal direction, and a current flowing through the voltage was measured to obtain a resistance value of about 47 KΩ.
(Substantially the original low resistance value of Cu). This is two orders of magnitude lower than the resistance of a Cu wiring formed to the same size as the above by the conventional method of forming a Cu wiring was about 5.7 MΩ.

FIGS. 2A to 2E show a modification of the above embodiment. In the above embodiment, a 0.3 μm thick Cu film is formed on an insulating film by a sputtering method. However, in this case, a Cu film is formed by a plating method. Therefore, except for FIG. 2B and FIG. 2C, other parts are the same as FIG. 1A to FIG. 1E. The description is omitted.

In FIG. 2B, a Cu film 1 is formed on the insulating pattern 11 'patterned by the method shown in FIG.
Next, as shown in FIG. 2C, a Cu film 13 'is buried in holes and grooves by laser annealing to make it suitable for wiring.

Next, a semiconductor device manufacturing apparatus used in each of the above embodiments will be described. FIG. 3 is a plan view showing a configuration of a semiconductor device manufacturing apparatus according to an embodiment of the present invention.

The inside of the sealed space is kept at a vacuum, and a transfer robot 19 is built in the inside of the sealed space.
An unloader 21, a heating chamber 23 with a built-in ceramic heater 22, a Cu film oxidation forming chamber 24, and a laser beam irradiation chamber 25 are installed to form a multi-chamber. The transfer robot 19 has a support shaft (not shown) to which an arm for holding a rotatable wafer that expands and contracts is attached, and this arm has a structure capable of entering and exiting each of the chambers 23, 24, and 25.

An XY table 31 is built in the laser beam irradiation chamber 25. The XY table 31 has an optical system 30 for uniformizing the spatial intensity distribution of the laser beam and the transmission mirror 2.
9a is mounted. The transmission mirror 29a is provided at a position for receiving the laser beam from the laser oscillator 26 via the transmission mirrors 29b to 29d and the optical element (variable attenuator) 28.

With these configurations, the wafers after the Cu film formation are transferred to the transfer robot 19 in the vacuum chamber 20 one by one by the loader / unloader 21 in the wafer cassette. The transfer robot 19 transfers the wafer into the heating chamber 23 for forming a Cu oxide film. In the heating chamber 23, the wafer is heated to 400 ° C. by the ceramic heater 22.

Next, the transfer robot 19 is operated to transfer the heated wafer to the Cu oxide film forming chamber 24,
Oxygen gas is sealed in the u oxide film forming chamber 24, and a very surface layer of Cu is oxidized to a predetermined level.

Thereafter, the transfer robot 19 is operated to transfer the wafer 25 from the Cu oxide film forming chamber 24 to the laser beam irradiation chamber. In the laser beam irradiation chamber 25, the laser beam emitted from the laser oscillator 26 to the wafer passes through an optical element 28 (variable attenuator) for controlling the laser intensity and transmission mirrors 29a to 29d, and a laser beam spatial intensity distribution uniforming optics. The light is collected and irradiated by the system 30. In this irradiation, since the laser irradiation beam size on the wafer is 2.0 mm square, the wafer is scanned by the XY table 19 so as to cover the entire surface of the wafer.

As for the laser light irradiation, assuming that the output of one pulse of the laser oscillator 26 is 300 mJ, the transmission loss of the transmission optical system is 50%, and the irradiation size of the laser light to the wafer is 2.0 mm. The laser irradiation energy density on the wafer is 3.75 J / cm ² at the maximum.
Here, as shown in FIG. 8, if the heat treatment is to be performed to the upper limit of the melting region in the normal Cu, the Cu film thickness becomes 2.5
Up to μm is possible. Therefore, the thickness of the Cu film is 2.
For a film thickness greater than 5 μm, the size of the laser irradiation on the wafer must be reduced.

However, in the method according to the invention, C
Since only the very surface layer of the u film was oxidized, the reflectance spectrum was measured by 5 ° reflection with a spectrophotometer. As a result, FIG.
The Cu reflectance spectrum up to 90 nm is shown in FIG.
According to the present invention, the reflectivity of the Cu film was lowered as shown in the reflection spectrum obtained by exposing the surface layer of Cu to an oxygen atmosphere after heating at ℃.

Thus, the oscillation wavelength 308n of the laser beam
The absorption rate of the Cu film with respect to m is 65%, and the absorption rate is 8 when the Cu film is oxidized by exposure to an oxygen atmosphere after heating at 400 ° C.
0%. That is, in the formation of an oxide film at 400 ° C., the reflectance is reduced to 20%, so that it is possible to perform a heat treatment up to a Cu film thickness of 3.2 μm at 3.75 J / cm ² under the same conditions.

As for the oxide film on the surface of the Cu film,
Cu-CM after forming Cu film oxide film and after laser heat treatment
P (Chemical Mechanical1 Pol)
FIGS. 6 and 7 show the results of XPS analysis of the surface after the ising) treatment.

FIG. 6 shows the case where the surface layer of the Cu film was oxidized as in the present invention. The peak of the component ratio of CuO was observed, from which it was also seen that the Cu film was oxidized.

FIG. 7 shows that even when the oxidized Cu film is subjected to laser heat treatment and then subjected to the CMP treatment, the peak of CuO is not observed. It is determined that the film does not cause any particular increase in the resistance value of the wiring.

Therefore, according to the configuration and method of the present invention, the laser irradiation energy intensity with respect to the target heat treatment temperature of the Cu film can be reduced, and even when the Cu film thickness is large, the specifications of the laser heat treatment apparatus can be reduced. A desired heat treatment can be performed without any change.

In a normal case or when the Cu film thickness is small, the laser irradiation area can be widened.
The tact time of wafer processing can be shortened.

Although a Cu film is used in each of the above embodiments, it goes without saying that a Cu alloy film is included in the Cu film.

[0044]

According to the method for manufacturing a semiconductor device and the apparatus for manufacturing the same according to the present invention, it is possible to provide a method for improving the energy efficiency in heat treatment, which is intended in a laser heat treatment apparatus.

[Brief description of the drawings]

1A to 1E are cross-sectional structural views of a wafer in a manufacturing process according to a method for manufacturing a semiconductor device of the present invention.

FIGS. 2A to 2E are cross-sectional structural views of a wafer in a manufacturing process according to a modified example of the method for manufacturing a semiconductor device of the present invention.

FIG. 3 is a plan view showing a configuration of a semiconductor device manufacturing apparatus according to an embodiment of the present invention.

FIG. 4 shows a wavelength of 700 nm before oxidation of a Cu layer;
Graph of Cu reflectance spectrum up to 90 nm.

FIG. 5 is a graph of a reflection spectrum obtained by heating a Cu layer at 400 ° C. and then oxidizing a very surface layer of Cu.

FIG. 6 shows an XPS analysis result when a surface layer of a Cu film is extremely oxidized.

FIG. 7 shows a CM film subjected to laser heat treatment of a Cu film having an oxidized surface layer.
XPS analysis result when P processing was performed.

8 (a) to 8 (d) are cross-sectional structural views of a wafer by a process flow of a conventional laser melt method.

FIG. 9 is a graph showing a relationship between a Cu film thickness and an energy density related to laser irradiation.

[Explanation of symbols]

10, 10 '... silicon substrate, 11, 11' ... insulating film,
12, 12 '... wiring groove, 13, 13' ... Cu film, 23 ...
Heating chamber, 24 ... Cu film oxidation forming chamber, 25 ...
Laser light irradiation chamber

Claims (7)

[Claims] 2. A semiconductor device comprising: forming a wiring groove in an insulating film on a semiconductor substrate; forming a Cu film on the insulating film; irradiating the Cu film with a laser beam; The method of manufacturing a semiconductor device according to claim 1, wherein the surface of the Cu film is oxidized before the laser light is irradiated on the Cu film. 2. The oxidation treatment of the surface of the Cu film, wherein the semiconductor substrate is heated to a temperature of 200 ° C. or more and 500 ° C. or less by lamp annealing or an electric furnace and exposed to an oxygen gas atmosphere. Item 2. A method for manufacturing a semiconductor device according to Item 1. 3. The method according to claim 1, wherein the forming of the Cu film on the insulating film is performed by
2. The method according to claim 1, wherein the sputtering is performed by sputtering u.
A method for manufacturing a semiconductor device as described in the above. 4. The method according to claim 1, wherein the Cu film is formed on the insulating film by plating. 5. The method of manufacturing a semiconductor device according to claim 3, wherein said Cu film is irradiated with said laser beam to melt said Cu film to bury Cu in a wiring groove. 6. The method according to claim 1, wherein the Cu film is formed in a hole or a groove formed on the semiconductor substrate in a state suitable for buried wiring by laser annealing by irradiating the Cu film with laser light. A method for manufacturing a semiconductor device according to claim 4. 7. An apparatus for manufacturing a semiconductor device, comprising: forming a wiring groove in an insulating film on a semiconductor substrate, forming a Cu film on the insulating film, and irradiating the Cu film with laser light. An apparatus for manufacturing a semiconductor device, comprising: a laser beam irradiation chamber for irradiating a laser beam to a substrate; and a Cu film oxidation forming chamber for previously oxidizing the surface of the Cu film.