JPH0559552A - Formation of deposited film - Google Patents

Abstract

PURPOSE:To form a film of Al or Al alloy on an electron donative surface by subjecting a base body having the electron donative surface consisting of a non-single crystal material and a non-electron donative surface to a surface treatment, then supplying Al-contg. gaseous raw materials and reactive gases and heating the substrate or generating plasma. CONSTITUTION:The surface of the base body formed of an electron donative material 90, such as Si wafer, and a non-electron donative material 91, such as SiO2 film, is subjected to, for example, a hydrofluoric acid treatment to terminate the surface of the non-electron donative material 91 with hydrogen atoms. An alkyl aluminum halide and gaseous H2 for reduction are added as the gaseous raw materials to the space formed of the two materials at the time of forming the pure Al film or gaseous Si2H6 is further added to the above-mentioned gaseous mixture and such gaseous mixture is added to the above-mentioned space at the time of forming the Al-Si film. The gaseous mixture is then heated to >=450 deg.C cracking temp. of the gaseous raw material or the base body is put into a CVD device to generate the plasma, by which the high-quality film 22 of the pure Al or Al-Si is stably formed on the surface of the electron donative material 90 of the base body. The high-purity film of the Al or Al-Si is also formed on the non-electron donative material 91 having the reformed surface.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for forming a metal film,
In particular, the present invention relates to a method for forming an Al deposited film which can be preferably applied to wiring of a semiconductor integrated circuit device or the like.

[0002]

2. Description of the Related Art Conventionally, in electronic devices and integrated circuits using semiconductors, aluminum (A
1) or Al-Si or the like has been used. here,
Since Al is inexpensive and has high electrical conductivity, and a dense oxide film is formed on the surface, it is chemically protected inside and stabilized, and it has good adhesion with Si. Have the advantages of.

By the way, since the degree of integration of integrated circuits such as LSI has increased, and miniaturization of wiring and multi-layer wiring have been particularly required in recent years, it has never been possible with conventional Al wiring. Strict demands are being made. LS is becoming smaller and smaller due to increased integration.
The surface of I or the like has a large degree of unevenness due to oxidation, diffusion, thin film deposition, etching or the like. For example, electrodes and wiring metals must be deposited on a stepped surface without disconnection or in via holes having a small diameter and a deep diameter. 4M
Bit or 16 Mbit DRAM (dynamic RA
In M) and the like, the aspect ratio (via hole depth ÷ via hole diameter) of a via hole in which a metal such as Al has to be deposited is 1.0 or more, and the via hole diameter itself is 1 as well.
μm or less. Therefore, there is a need for a technique capable of depositing Al even in via holes having a large aspect ratio.

Moreover, Al or the like for filling the via hole and for wiring on the insulating film must be deposited, and the deposited film must be of extremely good quality.

Recently, a CVD method using dimethyl aluminum hydride has been used as a technique for forming an Al film.
It has been proposed by the present inventors.

Although this method is effective as a future ultrafine processing technology in semiconductor manufacturing technology, there is still room for improvement in order to increase the manufacturing yield of semiconductor devices, achieve cost reduction, and achieve commercial success. Is left. For example, the following points.

A step of forming an insulating film having a 0.8 μm square contact hole on a single crystal silicon substrate and selectively depositing single crystal aluminum in the contact hole by a CVD method utilizing DMAH and hydrogen; Then W
There is a step of forming a subbing layer of a conductive material such as titanium nitride or the like on the aluminum and the insulating layer, and a method of depositing aluminum on the entire surface to form a flat multilayer wiring portion. When this method is used, aluminum can be selectively deposited in the contact hole with good reproducibility, but it cannot be said that aluminum on titanium nitride can be deposited with good reproducibility as much as aluminum in the contact hole.

Similarly, when a barrier metal such as titanium nitride is formed in the contact hole and aluminum is selectively deposited on the barrier metal, the reproducibility may be inferior to that when the barrier metal is directly deposited on the single crystal silicon. ..

Further, it has been discovered that when the heat treatment process in the semiconductor manufacturing process is repeatedly applied, the wiring is broken or short-circuited. This is particularly noticeable when forming three or more layers of wiring.

As a result of repeated experiments conducted by the inventors of the present invention, it was found that the following causes synergistically reduce the final yield.

First, one is the formation of defects during the initial deposition of aluminum. Next, there is a problem of the interface between the aluminum deposited in the contact hole and the aluminum deposited thereon. And there is the issue of stress migration.
Furthermore, there is a difference in the yield during film formation and a difference in film quality between the aluminum in the contact hole and the aluminum thereover, that is, aluminum on the insulating film.

An object of the present invention was made in view of the above-mentioned technical problems, and it is an object of the present invention to provide a method for forming a metal film which is free from Al spikes and has excellent step coverage to obtain a flat multilayer wiring.

Another object of the present invention is to provide a metal film forming method which is excellent in stress migration and durability.

Another object of the present invention is a chemistry for terminating an electron donating surface with a hydrogen atom on a substrate having an electron donating surface and a non-electron donating surface made of a non-single crystal material. After the surface treatment, the step of disposing the substrate in the space for forming the deposited film, the step of introducing a gas of alkylaluminum hydride into the space for forming the deposited film, and the decomposition temperature of the alkylaluminum hydride or higher. And maintaining the temperature of the substrate at a predetermined temperature, and selectively forming a metal film containing aluminum as a main component on the electron donative surface. To do.

Another object of the present invention is to arrange a substrate having an electron donating surface and a non-electron donating surface made of a non-single crystal material in a space for forming a deposited film of a CVD apparatus capable of generating plasma. And a step of introducing a gas of alkyl aluminum hydride into the space for forming the deposited film,
Maintaining the temperature of the electron-donating surface at a predetermined temperature equal to or higher than the decomposition temperature of the alkylaluminum hydride, and selectively forming a metal film containing aluminum as a main component on the electron-donating surface; ) A step of generating plasma in the apparatus while introducing the alkylaluminum hydride gas to form the aluminum-based metal film and the aluminum-based metal film on the non-electron-donating surface. And a plasma region including a plasma region in which the electron density of the plasma is 1 × 10 ^{8 to} 8 × 10 ¹⁰ cm ⁻³ near the surface of the substrate to form the metal film. To provide a forming method.

Another object of the present invention is to subject a substrate having an electron donating surface and a non-electron donating surface to a chemical surface treatment for terminating the electron donating surface with hydrogen atoms. After that, a step of disposing the substrate in a space for forming a deposited film, and introducing a mixed gas containing a gas of an alkylaluminum hydride into the space for forming a deposited film so that the partial pressure of the gas of the alkylaluminum hydride is 7 × 10 ^{-3 to} 9 × 10 ^-2 T
orr, and maintaining the temperature of the substrate at a predetermined temperature equal to or higher than the decomposition temperature of the alkylaluminum hydride, and selectively forming a metal film containing aluminum as a main component on the electron donative surface. Another object of the present invention is to provide a method for forming a metal film.

Another object of the present invention is a chemistry for terminating the electron-donating surface with a hydrogen atom on a substrate having an electron-donating surface and a non-electron-donating surface made of a non-single crystal material. After the surface treatment is performed, a step of arranging the substrate in a space for forming a deposited film, and introducing a gas of alkylaluminum hydride and hydrogen gas into the space for forming a deposited film, 7 × 1 partial pressure
0 ^{-3 to} 9 x 10 ^-2 Torr, and the decomposition temperature of the alkylaluminum hydride or higher and 450 ° C.
The present invention provides a method for forming a deposited film, which includes the step of maintaining the temperature of the substrate within the following range and selectively forming a metal film containing aluminum as a main component on the electron donative surface.

Another object of the present invention is to arrange a substrate having an electron donating surface and a non-electron donating surface made of a non-single crystal material in a space for forming a deposited film of a CVD apparatus capable of generating plasma. And the partial pressure of the alkylaluminum hydride gas is 7 × 10 ^{−3 to} 9 × 10 ⁻² Torr.
And a step of introducing into the space so that the substrate is maintained at a predetermined temperature higher than the decomposition temperature of alkylaluminum hydride and a metal film containing aluminum as a main component is selectively deposited on the electron donating surface. And the process of introducing alkyl aluminum hydride gas
Generating plasma in a VD apparatus to form a metal film containing aluminum as a main component on the metal film and the non-electron-donating surface, and the electron density of the plasma is 1 × 10 in the vicinity of the substrate surface. It is another object of the present invention to provide a deposited film forming method characterized in that plasma including a plasma region of ^{8 to} 8 × 10 ¹⁰ cm ⁻³ is generated to form the metal film.

(Description of Preferred Embodiments) First, a method of forming a deposited film using an organic metal will be outlined.

The decomposition reaction of the organic metal, and thus the thin film deposition reaction, greatly changes depending on the kind of metal atom, the kind of alkyl bonded to the metal atom, the means for causing the decomposition reaction, the atmosphere gas and the like.

For example, CH, which is the simplest alkyl group
_{Even with} an organic metal consisting of ₃ groups, C ₂ H ₅ group or iC ₄ H ₉ group and Al or Ga, the reaction form varies depending on the type of alkyl group, the type of metal atom and the method of excitation and decomposition. To deposit on the desired substrate:
The decomposition reaction must be very tightly controlled. For example, triisobutyl aluminum

[0022]

[Outer 1] In the case of depositing Al from Al, the conventional low-pressure CVD method, which is mainly based on a thermal reaction, causes unevenness of the order of μm on the surface, resulting in poor surface morphology. Further, hillocks are generated by heat treatment, Si surface is roughened by Si diffusion at the interface between Al and Si, and migration resistance is poor, which makes it difficult to use in a commercial-level VLSI process.

As described above in detail, due to the general property that the chemical properties of the organic metal greatly change depending on the type and combination of the organic substituents attached to the metal element, the CVD method using the organic metal forms the deposited film. The condition setting becomes complicated.

In addition, this is, for example, D of 4 Mbit or more.
When applied to a highly integrated circuit such as a RAM, the deposited film (wiring) cannot be used at all even if the film forming condition setting is slightly changed.

Then, it goes without saying that a deposited film of extremely good quality can be formed, but the film forming conditions are not extremely limited so that the apparatus becomes complicated, and the range is relatively versatile. It must be a method of forming a deposited film so as to obtain it.

Therefore, the present inventors prepared many organic metals with the aim of finding conditions exceeding the level applicable to high-integrated circuits, and the reaction gas, carrier gas, substrate temperature, and reaction state of gas. We conducted a number of experiments with different conditions and examined.

As a result, attention was paid to the use of alkylaluminum hydride as a raw material gas as a parameter capable of providing a versatile film forming condition. And
As a result of further studies, it was found that suitable film forming conditions applicable to the highly integrated circuit are as follows.

Alkyl aluminum hydride as a source gas, H ₂ as a reaction gas, a substrate having an electron donating surface (A) and a non-electron donating surface (B) as a substrate, and an electron donating surface (A as a substrate temperature). The temperature of () is not less than the decomposition temperature of aluminum hydride and not more than 450 ° C. According to such a film forming raw material, first, Al having excellent surface flatness and denseness can be deposited in the via hole.

Dimethylalkylaluminum hydride (DMAH) as an alkylaluminum hydride in the present invention is a substance known as an alkyl metal, but what kind of reaction mode and what kind of Al thin film is deposited is determined under all conditions. It was impossible to predict without forming a deposited film. For example D
In the example of shining MAH and depositing Al by CVD, the surface morphology is inferior and the resistance value is several μΩ to 10 μΩ · c.
m was larger than the bulk value (2.7 μΩ · cm), and the film quality was poor.

On the other hand, in the present invention, the CVD method is used to selectively deposit a good quality Al or Al-Si film as a conductive deposited film on the substrate.

That is, dimethyl aluminum hydride (DMAH), which is an organic metal, as a source gas containing at least one atom which is a constituent element of the deposited film.

[0032]

[Outside 2] Or monomethylalkylaluminum hydride (M
MAH ₂ )

[0033]

[Outside 3] In addition, H ₂ is used as a reaction gas, and an Al film is formed on the substrate by vapor phase growth using these mixed gases. Or dimethyl aluminum hydride (DMAH)
Or monomethyl aluminum hydride (MMAH
₂ ) and a gas containing Si as a source gas, and H ₂ as a reaction gas, and an Al—Si film is formed on the substrate by vapor phase growth using a mixed gas of these.

In one embodiment of the present invention, the partial pressure of the alkylaluminum hydride as the raw material gas is set to 7
It is set to x10 ^{-3 to} 9x10 ^-2 Torr. When Al is deposited under such a pressure condition, a good Al film that is particularly resistant to stress migration can be obtained.

The applicable substrate of the present invention has a first substrate surface material for forming a surface on which Al is deposited and a second substrate surface material for forming a surface on which Al is not deposited. Is. Then, a material having an electron donating property is used as the first substrate surface material.

This electron donating property will be described in detail below.

The electron-donating material is a material in which free electrons are present in the substrate or in which free electrons are intentionally generated. For example, by donating and donating electrons with source gas molecules attached on the substrate surface. A material having a surface on which a chemical reaction is promoted. For example, metals and semiconductors generally correspond to this. Those in which a thin oxide film is present on the metal or semiconductor surface are also included. This is because a chemical reaction occurs due to electron transfer between the substrate and the adhering raw material molecules.

Specifically, P, N, and I type semiconductors such as single crystal silicon, polycrystalline silicon, and amorphous silicon, II
Binary, ternary, or quaternary III-V group compound semiconductors formed by combining Ga, In, and Al as group I elements and P, As, and N as group V elements, or metals, alloys, and silicides Etc., such as Dangsten,
Molybdenum, tantalum, tungsten silicide, titanium silicide, aluminum, aluminum silicon,
It includes titanium aminium, titanium nitride, copper, aluminum silicon copper, aluminum palladium, titanium, molybdenum silicide, tantalum silicide and the like.

On the other hand, as a material for forming a surface on which Al or Al-Si is not selectively deposited, that is, a non-electron donating material, silicon oxide by thermal oxidation, CVD, sputtering, etc., BSG, PSG, BPSG
Such as glass or oxide film, thermal nitride film, plasma CVD,
A silicon nitride film or the like is formed by low pressure CVD, ECR-CVD, or the like.

On the substrate having such a structure, Al is deposited only by a simple thermal reaction in the reaction system of the source gas and H ₂ . For example, the thermal reaction in the reaction system of DMAH and H ₂ is basically performed at a substrate temperature of 160 ° C to 450 ° C.

[0041]

[Outside 4] The reaction of A causes only A on the surface having the electron donating material.
or Al-when a gas containing Si is added
It has been found that Si is deposited.

At the time of depositing pure Al, DMAH and H ₂ , Al
At the time of Si deposition, DMAH, Si ₂ H ₆ and H ₂ are used.

FIGS. 1 (a) to 1 (e) are schematic views showing the state of selective growth when DMAH and H ₂ or DMAH and Si ₂ H ₆ and H ₂ are used.

FIG. 1 (a) is a diagram schematically showing a cross section of the substrate before the formation of the Al or Al-Si deposited film. 90
Is a substrate made of an electron donating material, for example, a Si wafer. Reference numeral 91 is a thin film made of a non-electron donating material, for example, a thermally oxidized SiO ₂ film or a BSG film.

The substrate is subjected to a chemical treatment, which will be described in detail later, as a pre-deposition step to terminate the dangling bonds of surface atoms with hydrogen atom groups.

When a mixed substrate containing DMAH, Si ₂ H ₆ as a source gas and H ₂ as a reaction gas is supplied onto the substrate 1 heated within a temperature range of the decomposition temperature of DMAH or more and 450 ° C. or less. Then, Al-Si is deposited on the substrate 90, and a continuous film of Al-Si is formed as shown in FIG.

Continuing the deposition of Al-Si, FIG. 1 (c)
After that, as shown in FIG. 1D, the Al-Si film grows to the level of the uppermost part of the thin film 91. When further grown, as shown in FIG. 1E, the Al-Si film can grow up to 5000 Å with almost no lateral growth. This is the most characteristic point of the deposited film using DMAH and H ₂ or DMAH, H ₂ and Si ₂ H ₆ , and how a good quality film can be formed with good selectivity. You can understand.

As a result of analysis by Auger electron spectroscopy or photoelectron spectroscopy, contamination of impurities such as carbon and oxygen is not recognized in this film.

The resistivity of the deposited film thus formed is 2.7 to 3.0 μΩ · c at room temperature when the film thickness is 4000 Å.
The resistivity is substantially equal to that of m and Al bulk, and a continuous and flat film is formed. Further, even if the film thickness is 1 μm, the resistivity thereof is about 2.7 to 3.0 μΩ · cm at room temperature, and a sufficiently dense film can be formed even with a thick film. The reflectance in the visible light wavelength region is about 80%, and it is possible to deposit a thin film having excellent surface flatness and good stress migration property.

In the multi-layer wiring process in the VLSI, the via holes are selectively made of high quality A as shown in FIG.
The technique of embedding with 1 or Al-Si is essential. Further, after selectively depositing as shown in FIG. 1D, an electron donating material A as shown in FIG.
1 or on Al-Si and non-electron donating material. For example, Al on the thermally oxidized SiO ₂ film or CVD BSG film
Alternatively, if Al—Si can be deposited, it is possible to realize a highly reliable multi-layer wiring process in which wiring breakage or the like does not occur at the step portion.

As described in detail above, the selectivity of the Al film is extremely excellent in the selective growth on the electron-donating surface at a decomposition temperature of the alkylaluminum hydride or higher and 450 ° C. or lower using the alkylaluminum hydride and H ₂ . In addition, some contrivance is required to form the Al film on the thin film 91. Therefore, in view of this point, by modifying the surface of the non-electron-donating surface, an Al film is formed on the non-electron-donating surface that could not be deposited due to its selectivity before the surface modification. It is possible.

The surface modification described here is a step of supplying electrons and hydrogen to the surface of the non-electron-donating substrate.

Of course, if such a method is used, the following points in combination with the sputtering method, that is, C
After the VD process, when the wafer is transferred to another sputtering apparatus, the wafer is exposed to the atmosphere, so that the interface between the selectively grown Al film and the non-selectively formed Al film contains oxygen and the like. Needless to say, it is possible to improve the fact that a high resistance layer is formed, which causes an increase in contact resistance and it is difficult to realize a low resistance wiring.

FIGS. 2A to 2E show DMAH and H ₂ or DM on an electron donating surface made of a non-single crystal material.
It is a schematic diagram showing the selective growth when using the AH and Si ₂ H ₆ and H _2.

Generally, a non-single-crystal material is used as a base material on which Al constituting the wiring electrode is placed. Specifically, polycrystalline Si forming a gate electrode or wiring, a metal silicide material such as W silicide or Mo silicide having a polycide structure, W for preventing diffusion of Si and Al,
There are WSi ₂ , Mo and MoSi ₂ barrier metal materials.

The above-mentioned polycrystalline Si, metal silicide material, and barrier metal material are processed into a desired shape by a photolithography technique, an insulating film is deposited on the entire surface, and an opening portion is provided in a part of the insulating film to form an electrode material. Generally, embedded wiring is formed.

In one embodiment of the present invention, for example, "H ₂ SO ₄ / H ₂ O" is used as a pretreatment for depositing an Al film.
(= 1/3) and then HF / H ₂
After washing with O (= 1/200), washing with water and drying are performed again. The cleaning time of HF / H ₂ O is 60 seconds, and the final cleaning with water is 6 minutes. According to the TDS method, terminal hydrogen atoms were observed on the surfaces of the polycrystalline Si, the silicide material and the barrier metal material in the main cleaning, and it was possible to selectively deposit Al by DMAH based on the mechanism as described above.

FIG. 2 (a) is a diagram schematically showing a cross section of the substrate before the formation of the Al or Al-Si deposited film. 90
Is a substrate made of an electron donating material, for example, a Si wafer. 91 is a thin film made of a non-electron donating material, for example, a thermally oxidized SiO ₂ film or a BGS film.

Next, as shown in FIG. 2B, a polycrystalline W is selectively deposited in the openings using WF ₆ gas. Thereafter, the substrate is chemically treated as a pre-deposition step, and the surface of the W film 92 is terminated with hydrogen atom groups.

When a mixed substrate containing DMAH, Si ₂ H ₆ as a source gas and H ₂ as a reaction gas is supplied onto a substrate 90 heated within a temperature range of the decomposition temperature of DMAH or more and 450 ° C. or less. , Al-Si is deposited on the substrate 90, and an Al-Si continuous film 9 is formed as shown in FIG.
3 is formed.

Continuing the deposition of Al--Si, FIG.
2D, the Al—Si film grows to the uppermost level on the thin film 91, as shown in FIG. When further grown, as shown in FIG. 2E, the Al-Si film can grow up to 5000 Å with almost no lateral growth. This is the most characteristic point of the deposited film using DMAH and H ₂ or DMAH, H ₂ and Si ₂ H ₆ , and how a good quality film can be formed with good selectivity. You can understand.

As a result of analysis by Auger electron spectroscopy or photoelectron spectroscopy, contamination of impurities such as carbon and oxygen is not recognized in this film.

The resistivity of the deposited film thus formed is 2.7 to 3.0 μΩ · c at room temperature when the film thickness is 4000 Å.
The resistivity is substantially equal to that of m and Al bulk, and a continuous and flat film is formed. Further, even if the film thickness is 1 μm, the resistivity thereof is about 2.7 to 3.0 μΩ · cm at room temperature, and a sufficiently dense film can be formed even with a thick film. The reflectance in the visible light wavelength region is about 80%, and a thin film having excellent surface flatness can be deposited.

In the multi-layer wiring process in the VLSI, the via holes are selectively made of high quality A as shown in FIG.
The technique of embedding with 1 or Al-Si is essential. Further, after selectively depositing as shown in FIG. 2D, the electron donating material A as shown in FIG.
l or Al-Si and a non-electron donating material such as a thermally oxidized SiO ₂ film or a CVD BSG film with A
If 1 or Al-Si can be deposited, it is possible to realize a highly reliable multilayer wiring process in which wiring breakage or the like does not occur at the step portion.

As described in detail above, the selectivity of the Al film is extremely excellent in the selective growth of the alkylaluminum hydride on the electron-donating surface at the decomposition temperature or higher and 450 ° C. or lower using the alkylaluminum hydride and H ₂ . At the same time, some ingenuity is required to form the Al film on the thin film 91. Therefore, in view of this point, by modifying the surface of the non-electron-donating surface, an Al film is formed on the non-electron-donating surface that could not be deposited due to its selectivity before the surface modification. It is possible.

The surface modification described here requires a step of supplying electrons and hydrogen to the surface of the non-electron-donating substrate.

Of course, if such a method is used, the following points in combination with the sputtering method, that is, C
After the VD process, when the wafer is transferred to another sputtering apparatus, the wafer is exposed to the atmosphere, so that the interface between the selectively grown Al film and the non-selectively grown Al film contains oxygen and the like. Needless to say, it is possible to improve the point that the high resistance layer is formed, the contact resistance is increased, and it is difficult to realize the low resistance wiring.

Further, according to the present invention, it is possible to deposit Al or Al-Si as shown in FIG. 2 (f) with one CVD apparatus.

The operation of the present invention is as follows. First, DMAH and H ₂ or DMAH and Si ₂ H ₆ and H ₂
Is used to fill the via hole as shown in FIGS. After that, the non-electron-donating surface is effectively modified into an electron-donating material by modifying the surface to be an electron-donating material, Al or Al-Si surface, and the surface modification effectively becomes an electron-donating material. Al or Al-Si is uniformly deposited on the non-electron-donating material. The surface modification is to make the surface of the non-electron-donating surface as if free electrons exist and can contribute to the surface reaction. For example, there is a method of supplying free electrons to the surface by plasma treatment, ion irradiation, electron beam irradiation, or the like.
Also, if the SiO _2, there is a method of the non-electron donative surface subjected to irradiation of light having a greater energy than the forbidden band width of the SiO ₂ thereby to form a free electron.

For example, while supplying DMAH and H ₂ , RF
Generating the plasma provides electrons from the plasma onto the non-electron donating surface. When electrons are supplied to the surface, as is well known, H ₂ molecules are dissociated into H atoms and are present on the non-electron-donating surface to react with continuously flowing DMAH to deposit an Al film. Or, directly from the H ₂ plasma H
Atoms and electrons are supplied to the surface of the non-electron-donating substrate, and DM
There is a possibility of reacting with AH to form an Al film. According to the hypothesis to be described later, it is important that the DMAH is an asymmetric molecule, and the DMAH molecule is necessary for the reaction group CH ₃ for causing a surface reaction on the surface of the surface-modified substrate, and for sustaining the reaction. Having the essential genetic groups H (to form a surface equivalent to the modified surface) allows reactive deposition and continued reaction on the substrate surface.

When performing the surface modification in the above plasma, the electron density in the plasma in the vicinity of the substrate surface is 1 × 10 ^{8 to} 8 × 10 ¹⁰ cm ⁻³ , more preferably 5 × 10 ⁸ to 2 in the vicinity of the substrate surface. It is × 10 ⁹ cm ^-3 . The plasma power density is preferably 0.04 to 0.4 W / cm ³ . The vicinity of the substrate surface includes a region within 1 cm from the substrate surface. Specifically, the electron density in the center of the plasma is 1 × 10 ¹⁰ cm ⁻³ and the vicinity of the substrate surface is 1 × 10 ⁸ cm ⁻³ . The well-known TDS method and H
There are EELS methods, and the electron density of the present invention is determined by these measuring methods.

FIG. 3 is a schematic diagram showing an example of a deposited film forming apparatus to which the present invention can be applied.

Here, 1 is a substrate for forming an Al-Si film. The substrate 1 is placed on a substrate holder 3 provided inside a reaction tube 2 for forming a substantially closed space for forming a deposited film with respect to FIG. Quartz is preferable as a material forming the reaction tube 2, but it may be made of metal. In this case, it is desirable to cool the reaction tube. The substrate holder 3 is made of metal, and the heater 4 is provided so as to heat the substrate to be placed. The heat generation temperature of the heater 4 is controlled to control the substrate temperature.

The gas supply system 56 is constructed as follows.

In the present invention, it is preferable to utilize a supply system using a reduced pressure bubbling method to change the partial pressure ratio of DMAH. FIG. 4 shows a gas supply device by the reduced pressure bubbling method.

The hydrogen gas supplied from the supply gas line 110 has a desired flow rate through the supply gas main line 108 by the flow rate regulator 101 and the bubbler 1 containing DMAH and the like therein.
Send to 04. Hydrogen gas containing DMAH is introduced into the reaction tube 106 via the pressure regulator 105. 1 atm,
Since the vapor pressure of DMAH at room temperature is known to be about 2 Torr, the total pressure in the reaction tube is P _TOT , the partial pressure of _DMAH is P _DMAH , and the pressure inside the bubbler 104 is P _B. The relationship between the partial pressure of DMAH and the pressure inside the bubbler satisfies the following formula.

P _DMAH = P _TOT × 2 / P _B Based on this equation, the above-mentioned predetermined DMAH partial pressure can be obtained to achieve the object of the present invention. For example, when the total pressure (P _TOT ) in the reaction chamber is set to 1.5 Torr, the pressure regulator 105 adjusts the pressure (P _B ) inside the bubbler 104 to 100 Torr.
According to the above formula, the partial pressure of DMAH introduced into the reaction chamber (P _DMAH ) is 3 × 10 ^-2 Torr. In this way, it is possible to increase the partial pressure about 10 times as compared with the case where the bubbler internal pressure (P _B ) is 1 atm. By performing the same adjustment, the bubbler internal pressure (P _B ) is changed from 760 Torr to 14
The DMAH partial pressure is changed to 4. Torr to 4.
It can be varied from 0 × 10 ^{−3 to} 2.1 × 10 ⁻¹ Torr.

On the contrary, as a method of gradually decreasing the DMAH partial pressure, as shown in FIG. 4, the pressure inside the bubbler is brought close to 1 atm, and a part of the hydrogen gas from the supply gas line 110 is made to flow to the supply gas bypass line 109. , DMAH and hydrogen gas from the feed gas main line 108 and the reaction tube 106
The simultaneous partial introduction of the above-mentioned to gradually decreases the partial pressure of DMAH. The DMAH partial pressure can be controlled by the hydrogen flow rate of the main line 108 and the hydrogen flow rate of the bypass line 109.

The exhaust system is constructed as follows.

Reference numeral 7 is a gate bubble, which is opened when a large amount of gas is exhausted, such as when the inside of the reaction tube 2 is exhausted before the deposition film is formed. Reference numeral 8 is a sloree valve, which is used when exhausting a small volume such as when adjusting the pressure inside the reaction tube 2 when forming a deposited film. An exhaust unit 9 is composed of an exhaust pump such as a turbo molecular pump.

The transport system for the substrate 1 is constructed as follows.

Reference numeral 10 denotes a substrate transfer chamber capable of accommodating the substrate before and after the deposited film is formed, and the valve 11 is opened to exhaust the substrate. Reference numeral 12 denotes an exhaust unit for exhausting the transfer chamber, which is composed of an exhaust pump such as a turbo molecular pump.

The valve 13 is opened only when the substrate 1 is transferred between the reaction chamber and the transfer space.

An electrode 16 as a plasma generating means is installed around the reaction tube 2, and an AC power source 14 is connected to the electrode 16 to generate plasma.

As shown in FIG. 3, in the gas generating chamber for generating the first raw material gas, H ₂ or Ar (or another carrier gas as a carrier gas is used for liquid DMAH kept at room temperature). Bubbling with (inert gas) produces gaseous DMAH, which is transported to the mixer 14. H ₂ as a reaction gas is transported to the mixer through another route. The flow rate of the gas is adjusted so that the partial pressure of each gas becomes a desired value.

MMAH ₂ may be used as the first source gas, but DM gas sufficient to have a vapor pressure of 1 Torr at room temperature is used.
AH is most preferred. Also, DMAH and MMAH ₂
You may mix and use.

As the gas containing Si as the second source gas when forming the Al--Si film, Si ₂ H ₆ and S are used.
iH ₄ , Si ₃ H ₆ , Si (CH ₃ ) ₄ , SiCl ₄ , SiH
₂ Cl and SiH ₃ Cl can be used. Above all,
Si ₂ H _{6 which} is easily decomposed at a low temperature of 200 to 300 ° C. is most desirable. Gas such as Si ₂ H ₆ diluted with H ₂ or Ar is DMAH transported from another system to the mixer and supplied to the reaction tube 2.

When a gas is used for surface modification, a gas containing Si or a gas containing Ti such as TiCl ₄ is used for DMAH or S.
There is a method of transporting the gas containing i from a system different from the pipe to the mixer and supplying it to the reaction vessel 2.

In the case of depositing Al, DMAH and H ₂ , A
In the case of depositing l-Si, the mixed gas containing DMAH, Si ₂ H ₆ and H ₂ is at least the decomposition temperature of DMAH and 4
When supplied onto the substrate 1 heated within a temperature range of 50 ° C. or less, Al—Si is deposited on the substrate 90, and FIG.
A continuous film of Al or Al-Si is formed as shown in FIG.

When Al or Al-Si is continuously deposited under the above conditions, the Al or Al-Si film is formed on the uppermost part of the thin film 91 as shown in FIG. 1 (b) through the state of FIG. 1 (c). Grow to a level. The selectively deposited pure Al film is a single crystal.

Here, after performing the above-mentioned "surface modification step" of causing a surface reaction on the non-electron-donating surface while continuing to supply DMAH and Si ₂ H ₆ , DMAH and S
i ₂ H ₆ is continuously supplied to deposit Al or Al—Si in a shape as shown in FIG.

As described above, the substrate temperature is preferably not lower than the decomposition temperature of the source gas containing Al and not higher than 450 ° C., but specifically, the substrate temperature is from 200 to 450.
℃ is desirable, and if the deposition is performed under these conditions, DMAH
The partial pressure is 7 × 10 ^{−3 to} 9 × 10 ⁻² Tor of the pressure in the reaction vessel.
When r, the deposition rate is very large, 1000 Å / min to 3000 Å / min, and a sufficiently high deposition rate can be obtained as an Al-Si deposition technique for VLSI.

More preferably, the substrate temperature is 270 ° C. to 35.
The temperature is 0 ° C., and the Al—Si film deposited under these conditions has a strong orientation, and even if the heat treatment at 450 ° C. and 1 hour is performed tens of times, the Al—S film on the Si single crystal or Si polycrystalline substrate is used.
Good quality Al-
It becomes a Si film. In addition, such an Al-Si film has excellent electromigration resistance.

In other words, as the surface modification step here, H ₂ plasma is generated by Rf in the reaction tube in the H ₂ atmosphere, H atoms and electrons are supplied from the plasma to the non-electron donating surface, and When the electron donating surface is effectively modified to be an electron donating surface, the deposition as shown in FIG. 1 (e) is possible.
In addition to the excitation electrode 16 as the plasma generation electrode, the ground electrode 1
6'and 16 '' are provided. In the surface modification step, high frequency power of approximately 13.56 MHz is applied to the electrode 16 to generate plasma. The excitation electrode 16 is the ground electrode 1
Since it is sandwiched by 6'and 16 '', the excitation electrode 16
The electric lines of force from the two ends to the ground electrodes 16 ″ and 16 ′, and the plasma damage to the substrate 1 is extremely small. DMAH and H ₂ or DMAH and H ₂ and Si ₂ H ₆ are provided after selectively depositing Al or Al-Si on the electron donating surface on a substrate having an electron donating surface and a non-electron donating surface. Plasma is generated as it is. Electrons and hydrogen atoms are supplied from the plasma onto the non-electron-donating surface for surface modification. After the surface modification, the plasma is stopped and the deposition is continued.

When the plasma power and electron density are high, D
MAH is excited and decomposed, and large nuclei containing Al as a main component are generated in the surface modification step, and the surface morphology is significantly deteriorated. If the plasma power and the electron density are too small, the supply of electrons and hydrogen atoms will be insufficient, and the effect of surface modification will be greatly diminished. The pressure of the reaction tube at the time of surface modification is 0.1 to 5 Torr, the applied plasma power is 0.04 to 0.4 W / cm ^{−3 in} the apparatus of FIG. 4, and the surface modification time is 10 sec or more. The electron density in the vicinity is 5 × 10 ⁸ to 2 × 10 ⁹ cm ⁻³ .

After modifying the non-electron-donating surface, Al is non-selectively applied onto the electron-donating surface and the non-electron-donating surface.
Deposit. At this time, selectively deposited Al or A
l-Si and non-selectively deposited Al or Al-S
No carbon was detected at the i interface. After the surface modification process,
The deposition may be continued without stopping the plasma. Al or A deposited with plasma applied
The l-Si film quality was almost the same type as the film deposited without application of plasma. Further, the plasma power density applied during surface modification is smaller than the plasma power used in general plasma CVD, reactive ion etching, etc., and deposits on the surface of the reaction tube hardly occur.

In the apparatus of FIG. 3, 13.5 is required for plasma generation.
Although a high frequency power supply of 6 MHz was used, direct current or commercial frequency or microwave (for example, 2.45 GHz) discharge may be used.

Alternatively, a metal ultrathin film having an electron donating property may be formed on the non-electron donating surface.

The selective growth is determined by whether or not the reaction for forming the desired film occurs on the surface of the substrate.

Conventionally, the difference in whether selective growth occurs or not has been explained by the difference in adsorption points on the surface of the substrate. When the deposition selectivity occurs due to the difference in the adsorption points, for example, if the growth time is lengthened or the deposition temperature is lengthened, the deposition selectivity is impaired.

As an example of conventional selective growth, Si or W is S
There is a report that it grows on the surface of the i substrate, while it does not deposit on SiO ₂ .

However, in these examples of selective growth, it is known that when the growth time is long or the deposition temperature is long, nuclei of Si or W are generated on SiO ₂ and the selectivity of deposition is impaired. ing.

In order to apply the selective growth to the VLSI process, it is necessary that the deposited film has good film quality as well as good selectivity. That is, the formation of nuclei or the like should not occur on the surface that is not desired to be deposited.

In the Al deposition according to the present invention, it is deposited on the surface of the electron donating substrate, but Al is deposited on the non-electron donating substrate.
There is no nucleation and the selectivity is good.

The Al deposition reaction can be expressed by the equation (1) as a whole. With equation (1) alone, it is difficult to predict whether selective growth will occur. The reason why the present invention has very good selectivity is that the reaction of the formula (1) is considered microscopically.
It can be understood.

It can also be seen that single crystal Al is deposited on a single crystal Si substrate as described in the examples below. The reaction of equation (1) will be described for Al deposition on a single crystal Si substrate.

In general, cleaning with an ammonia system or treatment with a sulfuric acid-based chemical is performed, and finally, dipping in a dilute hydrofluoric acid solution and then cleaning with pure water. In such a cleaning step, the Si surface is in a state of being terminated with H atoms as shown in FIG.

On the other hand, on the surface of SiO ₂ , bonds of Si and O are closed and not terminated by H atoms or the like.

[0109]

[Outside 5] To form an electric double layer.

The substrate is heated in the deposition space and DMAH and H
_{When 2} is supplied, H ₂ dissociates on the Si surface to become H atoms and terminates on unbonded Si on the Si surface.

Here, the demand point is that H atoms are terminated on the Si surface instead of H ₂ molecules.

DMAH is said to have a dimer structure at room temperature, but is heated and adsorbed as a monomer on the substrate. As shown in FIG. 5A, the CH ₃ group is adsorbed on the substrate surface side.

It is said that the Al—CH ₃ bond is weakened by the presence of free electrons on the surface where free electrons are present. Further, it is known in the field of chemistry that a CH ₃ group originally reacts with an H atom at an activation energy of zero to react with an H atom to produce CH ₄ by the reaction of FIG. 5B (hereinafter referred to as methanation reaction). Has been. Terminate H atom on Si surface is

[0114]

[Outside 6] Furthermore, the methanation reaction is more likely to occur due to the catalytic action of free electrons existing on the surface.

The CH ₃ group reacts with the H ₂ molecule to give CH _3.
Yields ₄ , but CH ₃ + H (atoms) → CH ₄ and CH ₃ + 1 /
In the reaction of 2H ₂ (molecule) → CH ₄ , the methanation reaction with H atom occurs because the reaction rates are different by one digit or more. Figure 5
After the reactions (A) and (B), Al is deposited on Si which is an electron donating substrate. At this time, the important point is the source gas D
That is, the MAH has a CH ₃ group that easily reacts selectively with the termination atom on the surface of the substrate. When Al is deposited through (A) and (B) of FIG. 5, H atoms are terminated on the Al surface as shown in (C) of FIG. This is the same state as the initial state in FIG. Also, A
Since free electrons still exist in l, the H ₂ molecule dissociates into H atoms on the surface, so that the Al surface can be H terminated.

Thereafter, Al deposition continuously occurs due to the adsorption of DMAH and the methanation reaction.

First, the Si surface, which is terminated by H atoms, is genetically maintained after Al deposition. H atoms that terminate the Al surface after Al deposition are DMAH
The H atom in DMAH can be referred to as a genetic group capable of maintaining a terminated state. DM
The CH ₃ group in AH can be referred to as a selectively reactive group that selectively reacts with the surface termination atoms.

In summary, the Al deposition reaction is caused by the selective reaction between the terminal H atom on the surface and the CH ₃ group in DMAH. The termination H atom is supplied by the electron-donating substrate containing free electrons. It is the dissociation of H ₂ molecules on the surface and the free electrons on the surface of the electron-donating substrate that causes the methanation reaction.

Now, the surface of a non-electron-donating substrate such as SiO ₂ is generally not terminated with H atoms. Further, since there are no free electrons, even if a large amount of H ₂ molecules are supplied, they cannot be dissociated to form a terminated state. Moreover, since there are no free electrons, the Al—CH ₃ bond is not weakened, and the CH ₃ + H → CH ₄ reaction does not occur. Therefore, since there is no terminal H atom for Al deposition and no free electrons that cause a reaction, Al deposition does not occur on the non-electron-donating substrate.

Unlike the conventionally known reaction based on the difference of adsorption points, in the case of the DMAH + H ₂ system, it is supported by the two factors of the involvement of the terminate H atom and the free electron in the Al deposition reaction. The selectivity of is very good. Since H atoms remain in the terminated state on the Al surface after Al deposition, the Al selective growth may have a directional property, and the Al selective growth does not occur in the lateral direction as shown in FIG. 1E but grows in the vertical direction. It was also possible.

It has been clarified that it is the termination state of the surface and the free electrons that cause the reaction that cause the above-mentioned reaction. As a structure of the DMAH molecule itself, a CH ₃ group is formed around the Al atom. The feature is that different groups such as H atom are bonded. DMAH can be referred to as an asymmetric molecule in the sense that different CH ₃ groups and H atoms are bonded to the growing atoms constituting the deposited film, Al in this case.

Considering again Al growth on single crystal Si, it has already been described that the chemical treatment of the Si surface results in termination with H atoms, but the point to be noted here is that the termination H on single crystal Si is It means that they are regularly arranged in a plane. Therefore, Al deposited on the single crystal Si becomes a single crystal.

In the case where a metal such as Al is used as the electron-donating substrate containing free electrons, a surface H-terminate resulting from H atomization of H ₂ molecules due to the presence of free electrons or a case having d-electrons such as W As a result of dissociative adsorption of H atoms in the surface, H-terminated on the surface as well, as shown in FIG.
By the same reaction as in (B) and (C), Al is deposited only on the electron donating substrate.

In the field of organometallic chemistry, although there have been many studies on decomposition of organometals and reactions using organometals as catalysts, it has been publicly known that metal atoms in organometals are deposited on a desired substrate. No point is mentioned. The reaction according to the present invention has free electrons, and
It focuses on genetically maintaining the terminated state on the surface of the substrate, which is fundamentally different from the conventional decomposition and reaction of organic metal.

Al or Al-Si according to the present invention
The film obtained by the film forming method is dense, has extremely low content of impurities such as carbon, has a resistivity comparable to that of bulk, and has a high surface flatness. Reduction of hillocks during heat treatment Improvement of electromigration resistance Reduction of iron pits in contact area Improvement of wiring patternability by improving surface smoothness Improvement of resistance in via holes and contact resistance Reduction of heat treatment during wiring process It has various effects.

According to the method of the present invention, the deposited film is first selectively formed in the concave portion even on a substrate having a mixture of an electron donating material and a non-electron donating material and unevenness on the order of μm or submicron. After that, a uniform Al film can be formed on the entire surface of the substrate in the same film forming apparatus.

In the process of forming the multi-layer wiring of the VLSI,
The reduction in the thickness of the metal thin film in the uneven portion reduces the reliability of the wiring forming process.
According to the -Si film deposition method, a highly reliable Al, Al-Si film can be formed without a film thickness reduction or the like at the uneven portion.

In the conventional sputtering method, since it is difficult to form a film uniformly on the uneven portion, it is necessary to add a step to the opening cross section of the insulating film by a method such as reflowing by high temperature heat treatment. I was there.

However, the provision of the slope to the opening portion is a step which is contrary to the miniaturization technique because it requires an unnecessary area.

According to the present invention, Al and Al--Si are buried in a via hole having a vertical cross section, and the Al film formed thereafter has excellent flatness.
It is ideal as a wiring metal deposition method of I.

The chemical treatment before the deposition of the substrate is as follows.

A) Washing with "NH ₄ OH + H ₂ O ₂ + H ₂ O", followed by "washing with water" and subsequent "HF / H ₂ O"
= 1/40 ”followed by“ water washing ”or b)“ H ₂ SO ₄ / H ₂ O ₂ = 3/1 ”washing followed by“ water washing ”and then“ HF / H ₂ O = A pre-deposition chemical treatment in which a 1/40 "wash followed by a" + water wash "is used.

In this pretreatment, the surface of the substrate was
It becomes a state terminated with F atoms, and most of the F atoms are removed by the last washing with water, and a stable state in which H atoms are terminated is created on the surface of the substrate. Deposition was carried out on the substrate subjected to such pretreatment according to the examples described below.

(Example 1) The procedure for forming an Al film is as follows.

The surface of the single crystal Si substrate is thermally oxidized, and openings are formed by patterning. Selected CV using WF ₆
By the D method, a thin polycrystalline W film is formed only in the opening.

Then, the above-mentioned chemical treatment was performed.

Using the apparatus shown in FIG. 3, the inside of the reaction tube 2 is exhausted to about 1 × 10 ⁻⁸ Torr by the exhaust equipment 9.
However, Al is deposited even if the degree of vacuum in the reaction tube 2 is worse than 1 × 10 ⁻⁸ Torr.

After the Si wafer on which the W film is formed as described above is washed as described above, the transfer chamber 10 is released to atmospheric pressure and the Si wafer is loaded into the transfer chamber. The transfer chamber was evacuated to approximately 1 × 10 ^-6 Torr, and then the gate valve 13
Open and mount the wafer on the wafer holder 3.

After mounting the wafer on the wafer holder 3,
The gate valve 13 is closed, and the degree of vacuum in the reaction chamber 2 is about 1 ×.
Evacuate to 10 ^-8 Torr.

In this embodiment, DMA is applied from the first gas line.
Supply H. H ₂ was used as the carrier gas for the DMAH line. The second gas line is for H ₂ .

H ₂ is caused to flow from the second gas line and the opening degree of the slow leak valve 8 is adjusted to bring the pressure in the reaction tube 2 to a predetermined value. The typical pressure in this example is approximately 1.5.
Torr. After that, the heater 4 is energized to heat the wafer. After the wafer temperature reaches the specified temperature, DMAH
DMAH is introduced into the reaction tube through the line. The total pressure is about 1.5 Torr, and the DMAH partial pressure is about 1.5 x 1
0 ^-4 Torr. When DMAH is introduced into the reaction tube 2, Al is deposited. This Al film is referred to as a first Al film.

After the lapse of a predetermined deposition time, the high frequency (13:56 MH) was maintained without stopping the supply of DMAH.
z) A voltage is applied from the power supply to the excitation electrode 16 to generate H ₂ plasma. It should be noted that since similar ring-shaped electrodes are provided at both ends of the ring-shaped electrode to which RF is applied and are held at the ground potential, plasma shaping is possible. RF power was 20 W, electron density was 1 × 10 ⁹ cm ⁻³ near the substrate surface, and electron temperature was 6.5 near the substrate surface.
A plasma of ev was generated. That is, this step of supplying hydrogen atoms and electrons from the plasma to the substrate is the surface modification step. After the plasma irradiation for 1 minute, by stopping the supply of RF and continuing the supply of DMAH and H ₂ ,
Al is deposited on the already deposited Al film and the SiO ₂ film. The supply of DMAH is stopped after a predetermined deposition time has elapsed. The Al film deposited in this process is referred to as a second Al film.

In the temperature range of 160 ° C.-450 ° C. in the above sample, A was deposited on the SiO ₂ film in the first Al film deposition step.
l is not deposited, Al having the same film thickness as SiO ₂ is deposited only on the exposed portion of Si, and in the _second Al film deposition step,
Al is deposited on the Al film and SiO ₂ at almost the same deposition rate. Next, the heating of the heater 4 is stopped and the wafer is cooled. After stopping the supply of H ₂ gas and exhausting the inside of the reaction vessel,
The wafer is transferred to the transfer chamber, only the transfer chamber is brought to atmospheric pressure, and then the wafer is taken out. The above is the outline of the Al film forming procedure.

Next, the sample preparation in this example will be described.

A Si substrate (N type 1-2 Ωcm) was heated to 1000 by hydrogen combustion system (H ₂ : 41 / M, O ₂ : 21 / M).
Thermal oxidation was carried out at a temperature of ° C.

The film thickness was 7,000Å ± 500Å and the refractive index was 1.46. A photoresist is applied to the entire surface of this Si substrate, and a desired pattern is baked by an exposure device. The pattern is 0.25 μm x 0.25 μm to 100 μ
It is such that various holes of m × 100 μm are opened.
After developing the photoresist, reactive ion etching (RI
E) was used to etch the underlying SiO ₂ using the photoresist as a mask to partially expose the base Si. In this way, 0.25 μm × 0.25 μm to 100 μm × 1
130 samples having SiO ₂ holes of various sizes of 00 μm were prepared. Next, a W barrier metal of about 500 Å was formed by the CVD method using WF ₆ . 130 samples thus prepared were set at 13 substrate temperatures, and Al was deposited according to the above-described procedure on 10 samples at each substrate temperature.

First Al film deposition step, surface modification step, second step
The conditions of the Al film deposition step are as follows. Total pressure 1.5 Torr DMAH partial pressure 1.5 × 10 ⁻⁴ Torr during the first Al film deposition step Total pressure 1.5 Torr DMAH partial pressure 1.5 × 10 ⁻⁴ Torr RF power 20 W surface electron during surface modification step Density 1 × 10 ⁹ cm ⁻³ Plasma irradiation time 1 minute Total pressure 1.5 Torr DMAH partial pressure 1.5 × 10 ⁻⁴ Torr during the second Al film deposition step.

A deposited by changing the substrate temperature to 13 levels
The l-film was evaluated using various evaluation methods. The results are shown in Table 1.

[0149]

[Table 1]

In the above sample, Al was selectively deposited in the first Al deposition step in the temperature range of 160 ° C. to 450 ° C. only on the exposed Si portion to the same thickness as SiO ₂ . Further, in the second Al deposition step, Al was deposited at the same deposition rate on both the SiO ₂ surface and the Al film deposited in the first deposition step.

There was no difference between the selected Al film on Si and the Al film deposited on SiO ₂ after the surface modification process in film quality such as resistivity, reflectance, and hillock generation density after the heat treatment process.

Further, no resistance increase occurred at the interface between the first Al film and the second Al film.

(Example 2) In the pre-deposition treatment, as described above, "H ₂ SO ₄ / H ₂ O ₂ = 3/1" + "water washing" + "H"
F / H ₂ O = 1/40 ”+“ water washing ”was performed. On this occasion,
Final water washing time: Al was deposited in the same procedure as in Example 1 except that T was changed as follows.

The results are shown below.

[0155]

[Table 2]

The above results indicate that the surface of the substrate was terminated with H atoms and F atoms during the HF cleaning in the pretreatment, and the one with insufficient final water washing (T = 0 min) had many F atoms. The upper native oxide film is formed thicker than the other samples. When the final washing time is 3 to 15 minutes, the bond is broken only in the F atom, the situation in which the H atom contributing to the reaction is terminated becomes strong, and Al selectively grows.

If the final rinsing time is too long, the terminal H atom is broken or the natural oxide film is further decomposed by O ₂ , CO ₂ etc. dissolved in pure water by leaving it in pure water for a long time. Grow thick. The same was true when cleaning with ammonia / hydrogen peroxide solution was performed. After the selective deposition, the surface can be modified by plasma in the same manner as in Example 1, and then Al can be further deposited on the entire surface of the substrate to form the wiring.

Example 3 A 1 μm square quadrangular contact hole was formed in a single crystal wafer having an n ⁺ surface to have an aspect ratio of 1 or more. 1 such wafer
I prepared two. The number of contact holes formed on one wafer is 500,000.

Selective deposition and non-selective deposition were performed on this sample by the same film forming method as in Example 1 to form an Al film. The samples (1) to (12) were made different only in plasma electron density (DP) as film forming conditions.

Further, 50 wirings connecting 5,000 contact holes were formed on each wafer by photolithography, and open / short inspection of the wirings was performed.

As a result, the number of wirings having no defect is set to (M).

[0162]

[Outside 7]

Example 4 Two samples each prepared in Example 3 were prepared. 600 ° C. in N ₂ atmosphere
The mixture was heated at, and almost all the adsorbed hydrogen was desorbed.

Then, one sample was subjected to HF treatment and washed with water. After that, an Al film was formed in the same manner as in Example 3 and an open / short inspection was performed.

[0165]

[Outside 8]

As described above, according to the first to fourth embodiments, A in a via hole having an extremely fine and large aspect ratio is formed.
l or Al-Si deposition and fine Al or Al
-Si wiring is possible, and therefore it is effective as a hyperfine processing technology for highly integrated circuits, and the manufacturing yield thereof can be further improved.

(Example 5) The procedure for forming an Al film is as follows.

Using the apparatus shown in FIG. 3, the inside of the reaction tube 2 is exhausted to about 1 × 10 ⁻⁸ Torr by the exhaust equipment 9.
However, Al is deposited even if the degree of vacuum in the reaction tube 2 is worse than 1 × 10 ⁻⁸ Torr.

After the Si wafer is cleaned (that is, chemically treated) as described above, the transfer chamber 10 is released to the atmospheric pressure and the Si
The wafer is loaded into the transfer chamber. The transfer chamber is approximately 1 × 10 ^-6 T
After exhausting to orr, the gate valve 13 is opened and the wafer is mounted on the wafer holder 3.

After mounting the wafer on the wafer holder 3,
The gate valve 13 is closed, and the degree of vacuum in the reaction chamber 2 is about 1 ×.
Evacuate to 10 ^-8 Torr.

In the present embodiment, DMA is applied from the first gas line.
Supply H. H ₂ was used as the carrier gas for the DMAH line. For the second gas line H ₂ .

H ₂ is caused to flow from the second gas line and the opening degree of the slow leak valve 8 is adjusted to bring the pressure in the reaction tube 2 to a predetermined value. The typical pressure in this example is approximately 1.5.
Torr. After that, the heater 4 is energized to heat the wafer. After the wafer temperature reaches the specified temperature, DMAH
DMAH is introduced into the reaction tube through the line. The total pressure is about 1.5 Torr, and the DMAH partial pressure is about 2 × 10 ^-2.
Torr. When DMAH is introduced into the reaction tube 2, Al
Is deposited. This Al film is referred to as a first Al film.

After the predetermined deposition time has elapsed, the high frequency (13:56 MH) is maintained without stopping the DMAH supply.
z) A voltage is applied from the power supply to the excitation electrode 16 to generate H ₂ plasma. It should be noted that since similar ring-shaped electrodes are provided at both ends of the ring-shaped electrode to which RF is applied and are held at the ground potential, plasma shaping is possible. RF power was 20 W, electron density was 1 × 10 ⁹ cm ⁻³ near the substrate surface, and electron temperature was 6.5 near the substrate surface.
A plasma of ev was generated. That is, this step of supplying hydrogen atoms and electrons from the plasma to the substrate is the surface modification step. After the plasma irradiation for 1 minute, by stopping the supply of RF and continuing the supply of DMAH and H ₂ ,
Al is deposited on the already deposited Al film and the SiO ₂ film. The supply of DMAH is stopped after a predetermined deposition time has elapsed. The Al film deposited in this process is referred to as a second Al film.

In the temperature range of 160 ° C.-450 ° C. in the above sample, A was deposited on the SiO ₂ film in the first Al film deposition step.
l is not deposited, Al having the same film thickness as SiO ₂ is deposited only on the exposed portion of Si, and in the _second Al film deposition step,
Al is deposited on the Al film and SiO ₂ at almost the same deposition rate. Next, the heating of the heater 4 is stopped and the wafer is cooled. After stopping the supply of H ₂ gas and exhausting the inside of the reaction vessel,
The wafer is transferred to the transfer chamber, only the transfer chamber is brought to atmospheric pressure, and then the wafer is taken out. The above is the outline of the Al film forming procedure.

Next, sample preparation in this example will be described.

A Si substrate (N type 1 to ₂ Ωcm) was formed by a hydrogen combustion method (H ₂ : 41 / M, O ₂ : 21 / M) at 1000
Thermal oxidation was carried out at a temperature of ° C.

The film thickness was 7,000Å ± 500Å and the refractive index was 1.46. A photoresist is applied to the entire surface of this Si substrate, and a desired pattern is baked by an exposure device. The pattern is 0.25 μm x 0.25 μm to 100 μ
It is such that various holes of m × 100 μm are opened.
After developing the photoresist, reactive ion etching (RI
E) was used to etch the underlying SiO ₂ using the photoresist as a mask to partially expose the base Si. In this way, 0.25 μm × 0.25 μm to 100 μm × 1
130 samples having SiO ₂ holes of various sizes of 00 μm were prepared, the substrate temperature was set to 13 and Al was deposited on each of the 10 samples at the respective substrate temperatures according to the above-mentioned procedure.

First Al film deposition step, surface modification step, second step
The conditions of the Al film deposition step are as follows. Total pressure 1.5 Torr DMAH partial pressure 2 × 10 ⁻² Torr during first Al film deposition step Total pressure 1.5 Torr DMAH partial pressure 1.5 × 10 ⁻⁴ Torr RF power 20 W Surface electron density 1 during surface modification step × 10 ⁹ cm ^-3 Plasma irradiation time 1 minute Total pressure 1.5 Torr DMAH partial pressure 2 × 10 ^-2 Torr during the second Al film deposition step.

The Al film selectively deposited by changing the substrate temperature to 13 levels was evaluated by various evaluation methods. The results are shown in Table 2.

[0180]

[Table 3]

Next, based on Example 5 described above, Al was deposited by setting the substrate temperature to 270 ° C. and changing the partial pressure of DMAH.

The results are as follows

[0183]

[Outside 9]

Here, in order to evaluate the stress migration resistance, a sample further processed from that of Example 1 was used. It is made of Al (0.5μm thick) on the insulating film.
Is patterned to a width of 0.8 μm and a silicon nitride film is deposited (FIG. 5). Then, this was left under a temperature condition of 200 ° C., and the time until the Al film was cut was measured.

FIG. 6 is a schematic diagram showing the sample.

Reference numeral 200 is a Si substrate, 201 is a silicon oxide film having openings, 202 is an Al film, and 203 is a silicon nitride film.

As described above, when the partial pressure of DMAH is set to 7 × 10 ^{−3 to} 9 × 10 ⁻² Torr, Al can be deposited at a high deposition rate, and an Al film having good stress migration resistance can be obtained. Could be formed.

The interface characteristics between the selectively deposited Al film and the Al film non-selectively deposited by the plasma treatment were also excellent. It is considered that this is because incorporation of impurities and the like is hardly seen because the deposition rate is high.

In the above sample, Al was selectively deposited in the first Al deposition step in the temperature range of 160 ° C. to 450 ° C. only in the exposed Si portion to the same thickness as SiO ₂ . This film was a single crystal. Further, in the second Al deposition step, SiO
₂ Al was deposited at the same deposition rate on both the surface and the Al film deposited in the first deposition step.

There was no difference between the selected Al film on Si and the Al film deposited on SiO ₂ after the surface modification process in film quality such as resistivity, reflectance and hillock generation density after the heat treatment process.

Further, the resistance did not increase at the interface between the first Al film and the second Al film.

(Example 6) In the deposition pretreatment in Example 5, as described above, "H ₂ SO ₄ / H ₂ O ₂ = 3/1".
+ “Washing” + “HF / H ₂ O = 1/40” + “Washing” were performed. At this time, Al was deposited in the same procedure as in Example 1 except that the final washing time T was changed as follows.

The results are shown below.

[0194]

[Table 4]

The above results indicate that the surface of the substrate is terminated with H atoms and F atoms during the HF cleaning in the pretreatment, and the one with insufficient final water washing (T = 0 min) has many F atoms. The upper native oxide film is formed thicker than the other samples, and growth of the single crystal is hindered. When the final washing time is 3 to 15 minutes, the bond is broken only in the F atom, and the H atom contributing to the reaction is terminated.
Single crystal Al grows selectively.

If the final rinsing time is too long, the terminal H atoms are broken off from the bonds, or left in pure water for a long time to dissolve the natural oxide film further due to O ₂ , CO _2, etc. dissolved in the pure water. It grows thick and prevents single crystallization during the main Al deposition. The same was true when RCA cleaning was performed. After the selective deposition, the surface was modified by plasma in the same manner as in Example 1, and then Al was further deposited on the entire surface of the substrate to form the wiring.

Example 7 A rectangular contact hole of 1 μm square was formed on a single crystal wafer having an n ⁺ surface so that the aspect ratio was 1 or more. 1 such wafer
I prepared two. The number of contact holes formed on one wafer is 800,000.

Selective deposition and non-selective deposition were performed on this sample by the same film forming method as in Example 5 to form an Al film. The samples (1) to (12) were made different only in plasma electron density (DP) as film forming conditions.

Further, 50 wirings connecting 10,000 contact holes were formed on each wafer by photolithography, and the open / short inspection of the wirings was conducted.

As a result, the number of wirings having no defect is set to (M).

[0201]

[Outside 10]

Example 8 Two samples each prepared in Example 7 were prepared. 600 ° C. in N ₂ atmosphere
The mixture was heated at, and almost all the adsorbed hydrogen was desorbed.

Then, one sample was subjected to HF treatment and washed with water. Then, an Al film was formed in the same manner as in Example 7 and an open / short inspection was performed.

[0204]

[Outside 11]

Example 9 A sample similar to that of Example 7 was prepared, and the yield was evaluated under the same conditions as in Example 7 while changing the DMAH partial pressure.

As a result, under the condition that the DMAH partial pressure is 7 × 10 ^{−3 to} 9 × 10 ⁻² Torr, the sample (2) (that is, the plasma electron density 8 × 10 ⁷ cm ⁻³ ) and the sample (1
1) (namely, plasma electron density 1 × 10 ¹¹ cm ⁻³ ), the value of M was improved to about (M =) 40.

According to this embodiment, it is possible to form a metal film containing Al as a main component, which has a high resistance against stress abrasion and has a good film quality, at a high deposition rate.

Example 10 In the same manner as in Example 1, a sample having contact holes formed in SiO ₂ on single crystal Si was prepared.

In the same manner as in Example 1, a thin polycrystalline tungsten (W) film was formed in the contact hole by the selective deposition method using WF ₆ .

Chemical surface treatment was performed in the same manner as in Example 1 to terminate unbonded hands on the W film surface with hydrogen.
After that, the partial pressure condition of DMAH was set to A in the same manner as in Example 5.
When the 1-layer film was formed, the properties of the finished sample were superior to those of Examples 1 and 5. In particular, it is possible to provide a highly reliable semiconductor device that has a high probability of being produced with excellent migration resistance, is highly reproducible.

[0211]

According to the present invention, contactability is improved when connecting a non-single crystal electrode such as a gate electrode, a barrier metal or a polysilicon electrode to an Al wiring.
A deposited film having excellent reproducibility can be formed.

Further, according to the present invention, by controlling the plasma, the reliability is improved even in the deposition of the Al film on the non-electron donating surface.

Further, according to the present invention, the deposition rate of the Al film can be improved by controlling the partial pressure of the organic metal.

[Brief description of drawings]

FIG. 1 is a schematic diagram for explaining how a metal film is formed according to the present invention.

FIG. 2 is a schematic diagram for explaining a state of forming a metal film according to the present invention.

FIG. 3 is a schematic view showing an example of a metal film forming apparatus suitable for application of the present invention.

FIG. 4 is a schematic diagram showing a gas supply system for a metal film forming apparatus, which is preferable for application of the present invention.

FIG. 5 is a schematic diagram for explaining a mechanism of selective growth of Al.

FIG. 6 is a schematic diagram showing a sample for stress migration evaluation.

[Explanation of symbols]

 90 base 91 insulating film 92, 93 metal film

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H01L 21/285 301 L 7738-4M 21/3205

Claims (16)

[Claims] 1. A substrate having an electron-donating surface and a non-electron-donating surface made of a non-single crystal material is subjected to a chemical surface treatment for terminating the electron-donating surface with hydrogen atoms. After that, a step of disposing the substrate in a space for forming a deposited film, a step of introducing a gas of alkylaluminum hydride into the space for forming a deposited film, and a step of controlling the temperature to a predetermined temperature equal to or higher than the decomposition temperature of the alkylaluminum hydride. A step of maintaining the temperature of the substrate and selectively forming a metal film containing aluminum as a main component on the electron-donating surface. 2. The deposited film forming method according to claim 1, wherein the alkyl aluminum hydride is dimethyl aluminum hydride. 3. The deposited film forming method according to claim 1, wherein the alkylaluminum hydride is monomethylaluminum hydride. 4. The deposited film forming method according to claim 1, wherein the chemical surface treatment includes a cleaning step with ammonia and hydrogen peroxide solution. 5. The deposited film forming method according to claim 1, wherein the chemical surface treatment includes a cleaning step with sulfuric acid and hydrogen peroxide solution. 6. The deposited film forming method according to claim 1, wherein the chemical surface treatment includes a cleaning step with hydrofluoric acid. 7. The deposited film forming method according to claim 6, wherein the chemical surface treatment further includes a washing step with water. 8. A step of arranging a substrate having an electron-donating surface and a non-electron-donating surface made of a non-single crystal material in a space for forming a deposited film of a CVD apparatus capable of generating plasma, and an alkylaluminum. A step of introducing a gas of hydride into the space for forming the deposited film, maintaining the temperature of the electron-donating surface at a predetermined temperature equal to or higher than the decomposition temperature of the alkylaluminum hydride, and forming a metal film containing aluminum as a main component. Selectively forming on the electron-donating surface, and (d) plasma is generated in the apparatus while introducing the alkylaluminum hydride gas, and the metal film containing aluminum as a main component and the non-electron-donating material. Forming a metal film containing aluminum as a main component on the surface of the substrate, the electron density of the plasma being near the surface of the substrate. A method for forming a deposited film, characterized in that plasma including a plasma region of 1 × 10 ^{8 to} 8 × 10 ¹⁰ cm ⁻³ is generated to form the metal film. 9. The deposited film forming method according to claim 1, wherein the alkyl aluminum hydride is dimethyl aluminum hydride. 10. The method for forming a deposited film according to claim 1, wherein the electron density of the plasma is 5 × 10 ^{8 to} 2 × 10 ⁹ cm ⁻³ near the surface of the substrate. 11. A substrate having an electron-donating surface and a non-electron-donating surface is subjected to a chemical surface treatment for terminating the electron-donating surface with hydrogen atoms, and then used for forming a deposited film. The step of disposing the substrate in the space, and introducing a mixed gas containing a gas of alkylaluminum hydride into the space for forming the deposited film so that the partial pressure of the gas of the alkylaluminum hydride is 7 × 10 ^{−3 to} 9 × 10.
^-2 Torr, maintaining the temperature of the substrate at a predetermined temperature higher than the decomposition temperature of the alkylaluminum hydride, and selectively forming a metal film containing aluminum as a main component on the electron-donating surface. And a method for forming a metal film. 12. The method for forming a metal film according to claim 1, wherein the metal film is pure aluminum. 13. The method for forming a metal film according to claim 1, wherein the metal film contains silicon atoms. 14. The method of claim 1, wherein the alkyl aluminum hydride is dimethyl aluminum hydride. 15. A substrate having an electron-donating surface and a non-electron-donating surface made of a non-single crystal material is subjected to a chemical surface treatment for terminating the electron-donating surface with hydrogen atoms. After that, a step of disposing the substrate in a space for forming a deposited film,
The gas of alkyl aluminum hydride and hydrogen gas are introduced into the space for forming the deposited film, and the partial pressure of the gas of alkyl aluminum hydride is 7 × 10 ^{−3 to} 9 × 10 ^−2.
In the step of forming Torr, the temperature of the substrate is maintained within the range of not lower than the decomposition temperature of the alkylaluminum hydride and not higher than 450 ° C., and a metal film containing aluminum as a main component is selectively formed on the electron donative surface. And a step of forming the deposited film. 16. A step of arranging a substrate having an electron-donating surface and a non-electron-donating surface made of a non-single crystal material in a space for forming a deposited film of a CVD apparatus capable of generating plasma, and an alkylaluminum. Introducing a gas of hydride into the space so that the partial pressure thereof is 7 × 10 ^{−3 to} 9 × 10 ⁻² Torr, and maintaining the substrate at a predetermined temperature equal to or higher than the decomposition temperature of the alkylaluminum hydride to remove aluminum. A step of selectively depositing a metal film as a main component on the electron-donating surface; and a plasma is generated in the CVD device while introducing a gas of alkylaluminum hydride to generate a metal film and the non-electron-donating material. A step of forming a metal film containing aluminum as a main component on the surface,
And the electron density of the plasma is 1 × 1 near the substrate surface.
A deposited film forming method, characterized in that a plasma containing a plasma region of 0.8 to ⁸ × 10 ¹⁰ cm ⁻³ is generated to form the metal or film.