JP2721021B2 - Deposition film formation method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for forming a deposited film, and more particularly 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.

[Prior Art] Conventionally, in an electronic device or an integrated circuit using a semiconductor, electrodes (Al) or Al
-Si and the like have been used. Here, Al is inexpensive and has high electric conductivity, and a dense oxide film is formed on the surface.
It has many advantages such as stabilization by chemically protecting the inside and good adhesion to Si.

By the way, the integration degree of integrated circuits such as LSIs has increased, and in recent years, finer wiring and multilayer wiring have become particularly necessary in recent years. It is being issued. Along with miniaturization due to an increase in the degree of integration, the surface of an LSI or the like has become increasingly uneven due to oxidation, diffusion, thin film deposition, etching, and the like. For example, an electrode or a wiring metal must be deposited on a stepped surface without disconnection or deposited in a via hole having a small diameter and a large diameter. 4Mbit and 16Mbit DRA
In an M (dynamic RAM) or the like, the aspect ratio (via hole depth / via hole diameter) of a via hole on which a metal such as Al must be deposited is 1.0 or more, and the via hole diameter itself is 1 μm or less. Therefore, a technique that can deposit Al even in a via hole having a large aspect ratio is required.

In particular, in order to reliably connect to a device under an insulating film such as SiO ₂ , Al or Al—
It is necessary to deposit Si. For this purpose, a method is required in which Al is deposited only on the surface of Si or a metal, but not on an insulating film such as SiO ₂ .

Such selective deposition or selective growth cannot meet the above-mentioned requirements by the conventionally used sputtering method.

For example, in a bias sputtering method in which a bias is applied to a substrate and deposition is performed so that Al or Al-Si is buried only in a via hole by using a sputter etching action and a deposition action on a substrate surface, an adverse effect due to charged particle damage is caused. Not only occurs, but also because the etching action and the deposition action are mixed, the deposition rate is not improved.

Separately, various types of CVD (Chemical Vapor
Deposition) method has been proposed, but plasma CVD and optical C
Since VD has a reaction in the gas phase, the surface coverage with the unevenness on the substrate surface is relatively good. However, carbon atoms contained in the raw material gas molecules are taken into the film, and in particular, in plasma CVD, damage by charged particles (so-called plasma damage) occurs as in the case of the sputtering method.

Therefore, since the film grows mainly by the surface reaction on the surface of the base, the surface coverage with irregularities such as steps on the surface is good. If the thermal CVD method is used, it can be expected that deposition in the via hole is likely to occur.

For this reason, various thermal CVD methods have been studied as a method for forming an Al film.For example, a method in which organic aluminum is dispersed in a carrier gas, transported onto a heated substrate, and a film is formed by thermally decomposing gas molecules on the substrate is used. Will be For example, Journal of Ele
Ctrochemical Society No. 131 Volume 2175 pages triisobutylaluminum as an organic aluminum gas in the example seen in _{(1984) (i-C 4 HS 9} ) 3 Al using (TIBA), film formation temperature 260 ° C., the tube pressure 0.5torr 3.4μΩ ・ c
m film is formed.

However, this method has poor surface flatness of Al,
In addition, the Al in the via hole is inappropriate, for example, it does not become dense.

JP-A-63-33569 describes a method of forming a film by heating organic aluminum in the vicinity of a substrate. In this method, Al is selectively deposited only on the metal or semiconductor surface from which the natural oxide film on the surface has been removed by CVD.
Can be deposited. In this case, a step of removing the native oxide film on the substrate surface is required before introducing TIBA. In addition, it is necessary to heat the gas, and there is a restriction that the heating must be performed near the substrate, and it is difficult to determine how close the substrate must be heated. There are also problems such as location restrictions.

In addition, on page 75 of the proceedings of the 2nd Symposium of the Electrochemical Society of Japan (July 7, 1989), there is a device that uses TIBA according to the double-wall CVD method to raise the gas temperature of TIBA above the substrate temperature. Proposed.
This method is merely a modification of the above-mentioned JP-A-63-33569.
With this method, Al can be selectively grown only on metals and semiconductors.However, it is not only difficult to accurately control the difference between the gas temperature and the substrate surface temperature, but also if the cylinder and piping are not heated. There is a disadvantage that it does not. That is, if these are to be controlled, the apparatus is complicated, and a single-wafer processing type in which deposition can be performed on only one wafer in one deposition process has to be performed. In addition, a film that cannot be said to be of high quality can be obtained only at a deposition rate of at most 500 ° / min, but the throughput required for mass production cannot be realized. Moreover, even if the film is formed by this method, it is not sufficient to meet the above-mentioned requirements, for example, the film will not be uniform and continuous unless it is thickened to some extent, the flatness of the film is poor, and the selectivity for selective growth of Al cannot be maintained for a long time. .

In the case where trimethylaluminum (TMA) is used as another organic metal, Al deposition by using plasma or light has been attempted. Since it is a mold-type device, there is still room for improvement to sufficiently improve the throughput.

As described above, even if selective growth of Al can be performed by the conventional method, there is a problem in the flatness and denseness of the Al film. Is not good.

In addition, they have not been able to reach high throughputs that can ultimately achieve commercial success.

[Problems to be Solved by the Invention] As described above, in order to provide a highly integrated and high performance semiconductor device at a low cost in the semiconductor technical field where higher integration is desired in recent years. Had much room for improvement.

[Means for Solving the Problems] In order to achieve the above object, a deposited film forming method according to the present invention includes a method for forming a film containing aluminum as a main component by a thermal CVD method. Surface (A) and non-electron donating surface (B)
Disposing a substrate having a deposited film in a space for forming a deposited film; introducing an alkyl aluminum hydride gas and hydrogen gas into the space for forming a deposited film; and 450 ° C. or higher, which is equal to or higher than the decomposition temperature of the alkyl aluminum hydride. Maintaining the electron donating surface (A) within the following range, and changing the temperature so as to lower the temperature in the early stage of film formation and then increase it, or to reduce the partial pressure of the alkyl aluminum hydride in the early stage of film formation. Changing the partial pressure so as to lower and then increase the pressure to change the deposition rate of aluminum to selectively form an aluminum film on the electron donating surface (A). It is characterized by the following.

Further, the method for forming a deposited film according to the present invention is a method for forming a film containing aluminum as a main component by a thermal CVD method, wherein an electron donating surface (A) and a non-electron donating surface (B) are used.
Disposing a substrate having a deposited film in a space for forming a deposited film; introducing a gas of alkyl aluminum hydride, a gas containing Si and a hydrogen gas into the space for forming a deposited film; and a decomposition temperature of the alkyl aluminum hydride. Maintaining the electron donating surface (A) within the range of not less than 450 ° C. and lowering the temperature in the early stage of film formation and changing the temperature so as to increase it later, or alkyl aluminum in the early stage of film formation. At least one of changing the partial pressure of the hydride to lower and then increase the partial pressure of the hydride changes the deposition rate of aluminum containing silicon to change the silicon-containing aluminum film to the electron donating surface ( A) is characterized in that it has a step of selectively forming it.

[Action] In the present invention, a gas of alkyl aluminum hydride or a gas of alkyl aluminum hydride and a gas containing silicon are provided on a substrate having an electron donating surface (A) and a non-electron donating surface (B). To form an Al or Al—Si film only on the electron donating surface (A), and change the deposition rate of Al during film formation. Therefore, a dense Al or Al-Si film can be formed at a high speed only on the electron-donating surface (A) on the substrate.

Example First, a method for forming a deposited film using an organic metal will be outlined.

The decomposition reaction of organometallics and, consequently, the deposition reaction of thin films depend on the type of metal atom, the type of alkyl bonded to the metal atom,
It changes greatly depending on the conditions such as the means for causing the decomposition reaction and the atmospheric gas.

For example, in the case of M—R ₃ (M: Group III metal, R: alkyl group), trimethylgallium Is the thermal decomposition is radical cleavage to be cut of the Ga-CH ₃ bond, triethyl gallium Is due to β-elimination in thermal decomposition And C ₂ H ₄ . Also, triethyl aluminum with the same ethyl group Is a radical decomposition in which the Al—C ₂ H ₅ bond is broken in the thermal decomposition. But iC ₄ H ₉ bound isotributyl aluminum Leaves β.

Trimethylaluminum comprising a CH ₃ group and Al (TMA)
Has a dimeric structure at room temperature The thermal decomposition is a radical decomposition in which the Al—CH ₃ group is cleaved, and reacts with the atmosphere H ₂ at a low temperature of 150 ° C. or lower to generate CH ₄ , and finally generates Al. But almost 300 ℃
At the above high temperature, even if H ₂ is present in the atmosphere, the CH ₃ group extracts H from the TMA molecule, and finally an Al—C compound is generated.

In the case of TMA, light or H ₂ atmosphere high frequency (approximately 1
In restricted areas of power at 3.56MHz) plasma, C ₂ H ₆ are generated by the coupling of the crosslinking CH ₃ between two Al.

In short, even for the simplest alkyl groups CH ₃ , C ₂ H ₅ or iC ₄ H ₉ and organometallics consisting of Al or Ga, the reaction mode depends on the type of alkyl group, the type of metal atom, and the type of excitation. Since it depends on the decomposition means, in order to deposit metal atoms from an organometallic on a desired substrate, the decomposition reaction must be very strictly controlled. For example, triisobutylaluminum When depositing Al from
In the CVD method, irregularities on the order of μm are generated on the surface, and the surface morphology is inferior. In addition, hillocks are generated by heat treatment, Si surface roughness is caused by Si diffusion at the interface between Al and Si, and migration resistance is inferior, so that it is difficult to use it for a commercial-level VLSI process.

As described in detail above, the general property that the chemical properties of an organic metal greatly changes depending on the type and combination of organic substituents attached to a metal element. Becomes complicated.

Moreover, if this is applied to a highly integrated circuit such as a DRAM of 4 Mbit or more, a deposited film (wiring) which cannot be used at all even if the film forming condition setting is slightly changed.

Then, it goes without saying that an extremely high-quality deposited film can be formed. However, the film forming conditions are not extremely limited so as to complicate the apparatus, and can take a relatively versatile range. It must be a deposited film formation method.

Accordingly, the present inventors have prepared a large number of organic metals with the aim of finding conditions exceeding the level applicable to highly integrated circuits, and have prepared a large number of reaction gases, carrier gases, substrate temperatures, gas reaction states, and the like. The experiment was conducted and examined.

As a result, we focused on using alkylaluminum hydride as a source gas as a parameter that can provide highly versatile film forming conditions. As a result of further study, it was found that suitable film forming conditions applicable to highly integrated circuits are as follows.

Alkali 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 the temperature of the electron donating surface (A) as a substrate temperature But above the decomposition temperature of alkyl aluminum hydride and below 450 ° C. According to such a film forming material, firstly, Al having excellent surface flatness and denseness can be deposited in a via hole.

For example, dimethyl aluminum hydride DMAH as the alkyl aluminum hydride in the present invention
Is a substance known as an alkyl metal.However, what kind of reaction film forms an Al thin film cannot be predicted without forming a deposited film under all conditions. Was. For example, in the case where Al is deposited by photo-CVD using DMAH, the surface morphology is inferior, the resistance value is several μΩ to 10 μΩ · cm, which is larger than the bulk value (2.7 μΩ · cm), and the film quality is inferior.

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

That is, dimethyl aluminum hydride (DMAH) which is an organic metal is used as a source gas containing at least one atom serving as a constituent element of a deposited film. Or monomethyl aluminum hydride (MMAH ₂ ) And using H ₂ as a reaction gas, and selectively forming an Al film on the substrate by vapor phase growth using a mixed gas thereof. Alternatively, using a gas containing Si
Forming a Si film;

A substrate applicable to 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. . As the first substrate surface material, a material having an electron donating property is used.

 This electron donating property will be described in detail below.

An electron donating material is a material in which free electrons are present in a substrate or whether free electrons are intentionally generated. For example, a chemical reaction occurs when electrons are exchanged with a source gas molecule attached to a substrate surface. A material having a surface that is promoted. For example, metals and semiconductors generally correspond to this. Also included are those in which a thin oxide film exists on a metal or semiconductor surface. This is because a chemical reaction occurs between the substrate and the attached raw material molecules by electron transfer.

Specifically, semiconductors such as single crystal silicon, polycrystalline silicon, and amorphous silicon, and binary systems composed of a combination of Ga, In, Al as a group III element and P, As, N as a group V element Or a ternary or quaternary III-V compound semiconductor, or a metal, alloy, silicide, etc., such as tungsten, molybdenum, tantalum, tungsten silicide, titanium silicide, aluminum, aluminum silicon, titanium aluminum, titanium nitride,
Copper, aluminum silicon copper, aluminum palladium, titanium, molybdenum silicide, tantalum silicide and the like.

On the other hand, as a material forming a surface on which Al or Al-Si is not selectively deposited, that is, as a non-electron donating material, silicon oxide by thermal oxidation, CVD, etc., BSG, PSG, BPSG
Glass or oxide film, thermal nitride film, plasma CVD, decompression etc.
It is a silicon nitride film by CVD, ECR-CVD or the like.

Relative to the substrate in such a configuration, Al is deposited only in the simple thermal reaction in the reaction system of the source gas and H _2. For example
Thermal reaction in the reaction system between DMAH and H ₂ are essentially it is conceivable that. DMAH has a dimeric structure at room temperature.
As shown in the following examples, high quality Al or Al—Si can be deposited by MMAH ₂ by a thermal reaction.

Since MMAH ₂ has a low vapor pressure of 0.01 to 0.1 Torr at room temperature, it is relatively difficult to transport a large amount of raw material, and the deposition rate is an upper limit in the present invention satisfying the above-mentioned requirement of several hundred Å / min. Most preferably, DMAH with a vapor pressure of 1 Torr at room temperature is used.

FIGS. 1 (a) to 1 (e) show the inside of a via hole according to the present invention.
The state of selective growth of an Al or Al-Si film is shown.

FIG. 1 (a) is a diagram schematically showing a cross section of a substrate before forming an Al deposited film according to the present invention. 90 is a substrate made of an electron donating material, and 91 is a thin film made of a non-electron donating material.

DMAH, Si ₂ H ₆ as raw material gas and reactive gas
When the mixed gas containing H ₂ is supplied onto the substrate 1 heated under the first deposition condition, Al—Si is deposited on the substrate 90 and the first
An Al-Si continuous film is formed as shown in FIG.

Next, when the deposition of Al-Si is continued under the second deposition condition,
After the state shown in FIG. 1 (c), the Al-Si film grows to the uppermost level of the thin film 91 as shown in FIG. 1 (d). Further, when grown under the same conditions, as shown in FIG. 1 (e), the Al-Si film can grow up to 5000 ° with almost no lateral growth. This is the most characteristic point of the deposited film according to the present invention, and it can be understood how a good quality film can be formed with good selectivity.

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 has a thickness of 40
At 0 °, the resistivity is 2.7 to 3.0 μΩ · cm at room temperature, which is almost equal to the resistivity of the Al bulk, and is a continuous and flat film. In addition, film thickness 1μ
m, the resistivity is still approximately 2.7 to 3.0 at room temperature.
μΩ · cm, and a sufficiently dense film can be formed even with a thick film. The reflectance in the visible light wavelength region is also approximately 80%,
A thin film having excellent surface flatness can be effectively deposited at a high speed.

As described above in detail, in the present invention, the electron donating surface (A) is maintained at a temperature of not lower than the decomposition temperature of alkyl aluminum hydride and not higher than 450 ° C. in a mixed gas atmosphere of alkyl aluminum hydride gas and hydrogen gas. And selectively depositing Al on the electron donating surface (A), or as the above mixed gas atmosphere.
In addition to finding that Al-Si is selectively deposited by using a gas containing Si, in addition to Al or Al
-In order to increase the throughput in forming the Si film,
During the formation of the deposited film, the deposition rate is shifted from a low deposition rate to a high deposition rate. By doing so, high throughput can be achieved without deteriorating the film quality.

FIG. 2 is a schematic view showing a deposited film forming apparatus capable of depositing Al or Al-Si.

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 space for forming a deposited film which is substantially closed with respect to FIG. Quartz is preferred as a material constituting the reaction tube 2, but it may be made of metal. In this case, it is desirable to cool the reaction tube. The base holder 3 is made of metal, and is provided with a heater 4 so as to heat the mounted base. The temperature of the substrate can be controlled by controlling the heat generation temperature of the heater 4.

 The gas supply system is configured as follows.

Reference numeral 5 denotes a gas mixer, which mixes the first source gas, the second source gas, and the reaction gas and supplies them to the reaction tube 2. Reference numeral 6 denotes a source gas vaporizer provided for vaporizing an organic metal as a first source gas.

Since the organic metal used in the present invention is in a liquid state at room temperature, the carrier gas passes through the organic metal liquid into saturated vapor in the vaporizer 6 and is introduced into the mixer 5.

 The exhaust system is configured as follows.

Reference numeral 7 denotes a gate valve which is opened when exhausting a large amount of gas, such as when exhausting the inside of the reaction tube 2 before forming a deposited film.
Reference numeral 8 denotes a slow leak valve, which is used when a small volume of gas is exhausted, for example, when adjusting the pressure inside the reaction tube 2 when forming a deposited film. Reference numeral 9 denotes an exhaust unit, which includes an exhaust pump such as a turbo molecular pump.

 The transport system for the base 1 is configured as follows.

Reference numeral 10 denotes a substrate transfer chamber capable of housing a substrate before and after forming a deposited film, and is evacuated by opening a valve 11.
Reference numeral 12 denotes an exhaust unit for exhausting the transfer chamber, which is constituted by 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.

As shown in FIG. 2, in a gas generation chamber 6 for generating a first raw material gas, H ₂ or Ar (or other non-magnetic) as a carrier gas is supplied to a liquid DMAH maintained at room temperature. Bubbling with active gas) and gaseous DM
AH is produced and transported to the mixer 5. H ₂ as a reaction gas is transported to the mixer 5 from another route. The flow rate of each gas is adjusted so that its partial pressure becomes a desired value.

MMAH ₂ may be used as the first source gas, but DMAH sufficient for the vapor pressure to be 1 Torr at room temperature is most preferable.
It may also be used by mixing DMAH and MMAH _2.

The gas containing Si as the second source gas when forming the Al—Si film includes Si ₂ H ₆ , SiH ₄ , Si ₃ H ₈ , Si (C
H ₃ ) ₄ , SiCl ₄ , SiH ₂ Cl ₂ , and SiH ₃ Cl can be used. In particular, Si ₂ H _{6 which} is easily decomposed at a low temperature of 200 to 300 ° C. is most preferable. A gas such as Si ₂ H ₆ diluted with H ₂ or Ar is transported to the mixer 5 from a separate system from the DMAH and supplied to the reaction tube 2.

When the apparatus shown in FIG. 2 is used, a total pressure of 1.5 Torr DMAH partial pressure 1.5 × 10 ^-4 Torr Si partial pressure 2.0 × 10 ^-6 Torr Ai-Si film is made electron-donating under a substrate temperature of 160 ° C. to 450 ° C. It can be selectively deposited only on the material surface. Even if the film thickness is 400mm, it is continuous, and the resistivity is 2.7-3.0μ which is almost equal to the bulk value of Al.
Ω · cm. When the substrate temperature is 270 ° C-350 ° C, the deposition rate is
It is 100-800 ° / min, and higher deposition rates require higher deposition rates.

To achieve high-speed deposition, raise the substrate temperature,
It is conceivable to increase the AH partial pressure. For example, substrate temperature
A deposition rate of 0.2 to 0.5 μm / min can be realized at 330 ° C. and a DMAH partial pressure of 10 ⁻² to 10 ⁻³ Torr. However, if the deposition rate is too high, the surface will have poor surface flatness. For example, the reflectance is about 10 to 30% of Al or Al-
It becomes a Si film. As described above, a film having poor surface flatness is caused by a large surface migration of metal atoms or molecules at a high temperature. It is considered that the surface flatness is deteriorated. That is, the most important reason is that a film having poor surface flatness is formed in the initial stage of the deposition, and this has an adverse effect until later.

In the present invention, as a means for shifting from a low deposition rate to a high deposition rate at the time of deposition film formation, for example, using a method of changing the substrate temperature during deposition, the source gas partial pressure, at a substantially high deposition rate, and Al or high quality, excellent flatness
A method for obtaining an Al-Si deposited film is provided.

In this way, a high-quality flat deposition film having a substantially high deposition rate can be obtained.

In the formation of a deposited film by the surface chemical reaction according to the present invention, the condition of low substrate temperature and low deposition rate under low source gas partial pressure can be considered as a continuous and high quality film even if it is a thin film without contamination from the reaction tube. It is said.

According to the findings of the present inventors, good quality Al or Al-Si
The substrate is formed at a substrate temperature of 160 to 450 ° C., preferably 270 to 350 ° C., with good selectivity.

Therefore, the first deposition step in the present invention, that is, the deposition film formation step at a low deposition rate, is performed at a total pressure of 10 ^{−3 to} 760 Torr, preferably 5 × 10 ^{−2 to} 5 Torr, a substrate temperature of 270 to 350 ° C. Preferably 270-300
° C., DMAH partial pressure, 1.3 × 10 ^-5 ~ 1.3 × 10 ^-3 times the total pressure, preferably appropriately selected from the conditions of 1.3 × 10 ^-5 ~ 1.3 × 10 ^-4 times, continuous membrane What is necessary is just what is formed. In the second deposition step of the present invention, that is, as a deposition film formation step at a high deposition rate, the substrate temperature is 270 to 350 ° C. at a total pressure of 10 ^{−3 to} 760 Torr, preferably 5 × 10 ^{−2 to} 5 Torr. Preferably 300-350
° C, DMAH partial pressure shall be 1.3 × 10 ^{-5 to} 1.3 × 10 ^-3 times the total pressure.

To raise the substrate temperature, instead of using only a heater, irradiate the wafer surface with a W lamp or Xe lamp,
The substrate temperature may be raised rapidly. Heating with a lamp is effective in rapidly raising the substrate temperature,
Since a device such as a window is complicated, it is more desirable to raise the substrate temperature using a heater used for heating the substrate.

Preferably, it is appropriately selected from the conditions of 1.3 × 10 ^{−4 to} 1.3 × 10 ⁻³ times, and it is sufficient that a deposited film is formed at a deposition rate higher than the deposition rate in the first deposition step. For example, under the same total pressure, the substrate temperature is fixed and DM
The temperature may be increased by increasing the partial pressure of AH, or the substrate temperature may be increased while the partial pressure of DMAH is constant. Of course, both the substrate temperature and the partial pressure may be increased under the same total pressure.

Specifically, the first deposition step is to deposit a continuous film of 100 to 200 ° C. in the range of the substrate temperature of 270 to 300 ° C. under the above-mentioned pressure conditions, and then set the substrate temperature to 300 to 350 ° C. and set the deposition rate to It is preferable to increase the thickness to 0.1 to 1 μm / min.
The deposited film thus formed is a good quality film with surface migration suppressed.

When the deposition conditions are changed as described above, a continuous flat and high-quality film of 100 to 200 ° is formed under the first deposition condition in a deposition time of 1 to 5 minutes, and under the deposition conditions of I2, the film is already continuous and flat. Al (or Al-Si) is formed.
Even when Al (or Al-Si) is deposited at a high deposition rate of 1 to 1 μm / min, a flat and high-quality thin film can be formed.

An Al film having a thickness of 1 μm can be sufficiently formed with a deposition time of 1 to 5 minutes under the first condition and a deposition time of 1 to 3 minutes under the second condition.

In the apparatus shown in FIG. 2, Al-Si can be deposited on only one substrate in one deposition.

The method according to the present invention is applicable to a large number of low-pressure CVD apparatuses. Since the Al-Si deposition according to the present invention uses a surface reaction on the surface of the heated electron donating substrate, if the substrate is heated only by a hot wall type reduced pressure CVD method, D
The Al-Si containing 0.5 to 2.0% of Si by adding a Si source gas such as MAH and H ₂ and Si ₂ H ₆ can be rotated at a high deposition.

When using a low pressure CVD system, the reaction tube pressure is 0.05 to 760 Torr.
r, desirably 0.1 to 0.8 Torr. As a first deposition condition, the substrate temperature is 270 to 350 ° C., preferably 270 to 3 ° C.
00 ° C., the partial pressure of DMAH is 1.3 × 10 ^{−5 to} 1.3 of the partial pressure of the reaction tube pressure.
× 10 ⁻³ times, preferably 1.3 × 10 ^{−5 to} 1.3 × 10 ⁻⁴ times.
As the second deposition conditions, the substrate temperature is 270 to 350 ° C., preferably 300 to 350 ° C., and the DMAH partial pressure is the partial pressure of the reaction tube pressure.
1.3 × 10 ^{-5 to} 1.3 × 10 ^-3 times, desirably 1.3 × 10 ^{-4 to} 1.3 ×
10 ^-3 times. The Si ₂ H ₆ partial pressure, together with the first and second deposition conditions, is in the range of 1 × 10 ⁻⁷ to 1 × 10 ⁻⁴ times the reactor pressure,
Al-Si is deposited at a high rate only on the electron donating surface.

FIG. 3 is a schematic view showing a deposited film forming apparatus to which the present invention can be applied.

57 is a substrate for forming an Al-Si film. 50 is an outer reaction tube made of quartz which forms a space for forming a deposited film which is substantially closed with respect to the surroundings, and 51 is a quartz outer tube which is installed to separate a gas flow in the outer reaction tube 50. Inner reaction tube,
Reference numeral 54 denotes a metal flange for opening and closing the opening of the outer reaction tube 50, and the base 57 is installed in a base holder 56 provided inside the inner reaction tube 51. Note that the base holder 56 is desirably made of quartz.

In addition, the present apparatus can control the substrate temperature by the heater unit 59. The pressure inside the reaction tube 50 can be controlled by an exhaust system connected via a gas exhaust port 53.

The source gas is supplied to the first gas in the same manner as in the apparatus shown in FIG.
A gas system, a second gas system, a third gas system, and a mixer (all are not shown).
It is introduced into the reaction tube 50 from 52. As shown by an arrow 58 in FIG. 3, the raw material gas reacts on the surface of the substrate 57 when passing through the inside of the inner reaction tube 51, and deposits Ai-Si on the surface of the substrate. The gas after the reaction is supplied to the inner reaction tube 51 and the outer reaction tube.
The gas is exhausted from the gas exhaust port 53 through the gap formed by the gas exhaust port 50.

When the base is taken in and out, the base is lowered together with the base holder 56 and the base 57 by an elevator (not shown) of the metal flange 54, and is moved to a predetermined position to mount and remove the base.

By using such an apparatus and forming a deposited film under the conditions described above, high-quality Al-
Si films can be formed simultaneously.

According to the present invention, a continuous and dense Al-Si is formed in the initial stage of deposition, so that even if Al-Si is deposited under a high-speed deposition condition of 0.2 to 1 μm / min, the film quality such as surface flatness is increased. Does not deteriorate, and a high-quality Al-Si film can be effectively deposited at a high speed.

The Al-Si film obtained even when deposited at high speed is dense,
The content of impurities such as carbon is extremely small, the resistivity is comparable to that of bulk, and the surface flatness is extremely high. Al deposited
-Si film is deposited at high speed but has the following characteristics.

Reduction of hillocks Improvement of electromigration resistance Reduction of alloy pits in contact area Improvement of surface flatness Improvement of resistance in via hole and contact resistance Lower temperature of heat treatment during wiring process High quality Al-Si film Since the deposition can be performed at a high speed, the throughput in the VLSI process is dramatically improved. In a low-pressure CVD apparatus as shown in FIG. 2, Al-Si can be simultaneously deposited on 100 to 200 4-inch wafers, but the effect of high-speed deposition greatly contributes to an improvement in throughput. In the future VLSI, the wafer to be used will be 6 to 8 inches. When the wafer diameter increases to 6 inches or 8 inches, the decompression CV as shown in Fig. 2
It becomes difficult to practically use the D apparatus because the diameter of the reaction tube becomes large. However, the sheet-like CVD apparatus as shown in FIG. 2 is very advantageous for increasing the diameter of the wafer because the size of the entire apparatus does not change much even if the diameter of the wafer increases. But,
High-speed deposition of 0.2 to 1 μm / min cannot be realized by Al-Si deposition by the conventional CVD method, and even if a high-quality deposited film is formed, it has been difficult to use it practically. But,
By using the deposition method according to the present invention, high-quality Al-Si can be deposited at a high speed of 0.2 to 1 μm / min. The significance of the invention is extremely large.

(Example 1) First, the procedure of Al film formation is as follows.

Using the apparatus shown in FIG. 2, the inside of the reaction tube 2 is evacuated to approximately 1 × 10 ⁻⁸ Torr by the exhaust equipment 9. However, reaction tube 2
Even if the degree of vacuum inside is lower than 1 × 10 ⁻⁸ Torr, Al is deposited.

After cleaning the Si wafer, the transfer chamber 10 is released to the atmospheric pressure, and the Si wafer is loaded into the transfer chamber. The transfer chamber is evacuated to approximately 1 × 10 ⁻⁶ Torr, and then 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 reaction chamber 2 is evacuated until the degree of vacuum in the reaction chamber 2 becomes approximately 1 × 10 ⁻⁸ Torr.

In this embodiment, DMAH is supplied from the first gas line.
Carrier gas DMAH line with H _2. The second gas line and for H _2.

Flow H ₂ from the second gas line and use the slow leak valve 8
The pressure inside the reaction tube 2 is adjusted to a predetermined value by adjusting the opening of the reaction tube 2.
The typical pressure in this embodiment is approximately 1.5 Torr. Thereafter, the heater 4 is energized to heat the wafer. After the wafer temperature reaches a predetermined temperature, DMAH is introduced into the reaction tube from the DMAH line. The total pressure is approximately 1.5 Torr, and the DMAH partial pressure is approximately 1.5 × 10 ₋₄ Torr. When DMAH is introduced into the reaction tube 2, Al is deposited.

 The above is the first deposition step.

After forming a continuous Al film of about 100 to 200 ° in the first deposition step,
High-speed deposition is performed in a second deposition step. The conditions of the second deposition step are such that the total pressure is approximately 1.5 Torr and the partial pressure of DMAH is approximately 1 × 10 ⁻³ Torr. After a predetermined deposition time has elapsed, the supply of DMAH is stopped. Next, heating of the heater 4 is stopped, and the wafer is cooled.
After the supply of H ₂ gas is stopped and the inside of the reaction tube is evacuated, the wafer is transferred to a transfer chamber, and 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, preparation of a sample in this embodiment will be described.

Si substrate (N type 1-2 Ωcm) was converted to hydrogen combustion system (H ₂ : 4 l / M,
(O ₂ : 2 l / M) at a temperature of 1000 ° C.

The thickness was 7000 ± 500 ° and the refractive index was 1.46. A photoresist is applied to the entire surface of the Si substrate, and a desired pattern is baked by an exposure machine. The pattern is 0.25μm
Various kinds of holes of × 0.25 μm to 100 μm × 100 μm are formed. After developing the photoresist, reactive ion etching (RIE) is used to mask the underlying S
The iO ₂ was etched to partially expose the substrate Si. In this way, samples were prepared 130 sheets having 0.25μm × 0.25μm~100μm × 100μm various sizes SiO ₂ pores of,
The substrate temperature was set in 13 ways, and at the respective substrate temperatures, 10 samples were each subjected to the above-described procedure in the first deposition step, and the total pressure was 1.5 Torr, the DMAH partial pressure was 1.5 × 10 ⁻⁵ Torr, and the second deposition step was An Al film was deposited under the conditions of a total pressure of 1.5 Torr and a partial pressure of DMAH of 1.5 × 10 ⁻³ Torr.

The Al film deposited by changing the substrate temperature to 13 levels was evaluated using various evaluation methods. Table 1 shows the results.

In the above sample, Al was not deposited on SiO ₂ in the temperature range of 160 ° C. to 450 ° C., but Al was deposited only on portions where SiO ₂ was opened and Si was exposed. Note that the same selective deposition property was maintained when Al was deposited at 2 μm in the above temperature range.

When the substrate temperature in the first and second deposition steps exceeded 300 ° C., high-speed deposition of 0.5 to 1.0 μm / min was possible,
Slightly worse than when the surface reflectance is 300 ° C. or less. It is considered that the high temperature in the first deposition step is due to the poor flatness of the ultrathin Al film deposited in the first deposition step.

(Example 2) By the same procedure as in Example 1, the total pressure is 1.5 Torr DMAH partial pressure 1.0 × 10 ⁻⁵ Torr during the first deposition step. The substrate temperature is 270 ° C. or 300 ° C. The total pressure is during the second deposition step. Under the condition of 1.5 Torr DMAH partial pressure of 1.0 × 10 ^-3 Torr, Al was deposited by changing the substrate temperature in the second deposition step to several levels higher than that in the first deposition step.
Table 2 shows the results of various evaluations of the film.

There was no difference in the results obtained when the substrate temperature in the first deposition step was 270 ° C., 300 ° C.

As in Example 1, when the substrate temperature in the second deposition step exceeded 300 ° C., high-speed deposition of 0.5 to 1.0 μm / min was possible. The difference from Example 1 was that even when the substrate temperature in the second step was 330 ° C. or 350 ° C., an Al film with a high surface flatness having a reflectivity of 80 to 95% could be formed.

As in Example 1, Al was selectively deposited only on Si.
The selectivity was maintained even when Al was deposited up to 2 μm.

(Example 3) only the carrier gas DMAH by the same procedure as that in Example 1 and Ar instead of H _2, was Al deposition. From the second gas line
Supplying the H _2. As a result, Al was not deposited on SiO _{2 in} the temperature range of 160 ° C. to 450 ° C. as in Table 1 of Example 1, and Al was formed only in the portion where SiO ₂ was opened and Si was exposed. Was deposited. Note that the same selective deposition property was maintained when Al was deposited at 2 μm in the above temperature range.

When the substrate temperature in the first and second deposition steps exceeded 300 ° C., high-speed deposition of 0.5 to 1.0 μm / min was possible,
The surface reflectivity is slightly worse. It is considered that the high temperature in the first deposition step is due to the poor flatness of the ultrathin Al film deposited in the first deposition step.

(Example 4) only the carrier gas DMAH by the same procedure as that in Example 2 and Ar instead of H _2, was Al deposition. The second gas line was supplied H _2. When the substrate temperature in the first deposition step was 270 ° C. and 300 ° C., there was no difference in the obtained results. The film quality obtained is almost the same as in Table 2.

As in the case of the first or second embodiment, when the substrate temperature in the second deposition step exceeds 300 ° C., 0.5 to 1.0
High speed deposition of μm / min was possible. The difference from Example 1 and Example 2 is that the substrate temperature in the second step was 330 ° C. and 350 ° C.
The point is that an Al film having a high surface flatness having a reflectance of 80 to 95% was formed even at a temperature of ° C.

As in Example 1 and Example 2, Al was selectively deposited only on Si. The selectivity was maintained even when Al was deposited at 2 μm.

In the above sample, Al was not deposited on SiO ₂ in the temperature range of 160 ° C. to 450 ° C., but Al was deposited only on portions where SiO ₂ was opened and Si was exposed. Note that the same selective deposition property was maintained when Al was deposited at 2 μm in the above temperature range.

Example 5 An Al film was formed on a substrate (samples 5-1 to 5-179) having the following configuration using the low-pressure CVD apparatus shown in FIG.

Preparation of Sample 5-1 A thermally oxidized SiO ₂ film as a non-electron-donating second substrate surface material was formed on a single-crystal silicon as an electron-donating first substrate surface material. Patterning was performed by a photolithography process as shown in Example 1 to partially expose the single crystal silicon surface.

At this time, the thickness of the thermally oxidized SiO ₂ film was 7000 °, and the size of the exposed portion of the single crystal silicon, that is, the size of the opening was 3 μm × 3 μm. Thus, Sample 5-1 was prepared. (Hereinafter, such a sample is referred to as “thermally oxidized SiO ₂ (hereinafter abbreviated as T-SiO ₂ ) / single-crystal silicon”).

Preparation of Samples 5-2 to 5-179 Sample 5-2 was an oxide film (hereinafter abbreviated as SiO ₂ ) formed by normal pressure CVD / single crystal silicon Sample 5-3 was boron doped by normal pressure CVD Oxide film (hereinafter abbreviated as BSG) / single-crystal silicon, Sample 5-4 is phosphorus-doped oxide film (hereinafter abbreviated as PSG) / single-crystal silicon formed by atmospheric pressure CVD, Sample 5-5 is an atmospheric pressure CVD Sample 5-6 is a phosphorous and boron doped oxide film (hereinafter abbreviated as BSPG) / single crystal silicon. Sample 5-6 is a nitride film (hereinafter abbreviated as PS: N) / single crystal silicon formed by plasma CVD. Sample 5 -7 is a thermal nitride film (hereinafter abbreviated as TS: N) /
Sample 5-8 is a nitride film (hereinafter abbreviated as LP-S: N) / monocrystalline silicon formed by low-pressure DCVD. Sample 5-9 is a nitride film (hereinafter ECR-SiN) formed by an ECR device. Abbreviation) / single-crystal silicon. Further, Samples 5-11 to 5-179 shown in Table 3 were prepared by combining the first substrate surface material having an electron donating property and the second substrate surface material having a non-electron donating property.

Single-crystal silicon (single-crystal S
i), polycrystalline silicon (polycrystalline Si), amorphous silicon (amorphous Si), tungsten (W), molybdenum (M
o), tantalum (Ta), tungsten silicide (WS
i), titanium silicide (TiSi), aluminum (A
l), aluminum silicon (Al-Si), titanium aluminum (Ai-Ti), titanium nitride (Ti-N), copper (Cu), aluminum silicon copper (Al-Si-Cu), aluminum palladium (Al-Pd) ), Titanium (Ti), molybdenum silicide (Mo-Si), tantalum silicide (Ta-S
i) was used. These samples were placed in the reduced pressure CVD apparatus shown in FIG. 3, and an Al film was formed in the same batch.

 The deposition conditions are as follows.

During the first deposition step, the total pressure is 0.3 Torr, the DMAH partial pressure is 3 × 10 ⁻⁶ Torr, and the substrate temperature is 270 ° C. During the second deposition step, the total pressure is 0.3 Torr, the DMAH partial pressure is 10 × ⁴ Torr, and the substrate temperature is 330 ° C.

As a result of forming a film under these conditions, in all of the samples 5-1 to 5-179 subjected to patterning, deposition of Al occurs only on the surface of the electron-donating first substrate, and a depth of 7000 ° The opening of the hole was completely filled. Table 2 shows the film quality of the Al film.
There was no difference from that at 0 ° C., and the deposition rate in the second deposition step was very high, approximately 0.7 μm / min, for all substrates.

Example 6 An Al film was deposited in the same procedure as in Example 2, except that MMAH ₂ was used instead of DMAH.

The substrate used was the Si wafer shown in Example 1 on which the SiO ₂ thin film was patterned.

 The deposition process conditions are as follows.

During the first deposition step, the reaction tube pressure is 1.5 Torr MMAH ₂ partial pressure 5 × 10 ⁻⁵ Torr The substrate temperature is 270 ° C. During the second deposition step, the reaction tube pressure is 1.5 Torr MMAH ₂ partial pressure 1.0 × 10 ⁻³ Torr .

As in Example 2, the Al film was able to fill the opening of SiO ₂ at 7000 °, and the film quality of Al was not different from that of the second deposition step shown in Table 2 where the substrate temperature was 330 ° C.

The deposition rate of Al in the second deposition step is approximately 0.7 μm
There was no difference from using DMAH / min and DMAH.

In the above sample, Al was not deposited on SiO ₂ in the temperature range of 160 ° C. to 450 ° C., but Al was deposited only on portions where SiO ₂ was opened and Si was exposed. Note that the same selective deposition property was maintained when Al was deposited at 2 μm in the above temperature range.

Example 7 First, the procedure for depositing Al-Si is as follows.

Using the apparatus shown in FIG. 2, the inside of the reaction tube 2 is evacuated to approximately 1.0 × 10 ₋₈ Torr by the exhaust equipment 9. Even if the degree of vacuum in the reaction tube 2 is lower than 1.0 × 10 ₋₈ Torr, Al—Si is formed.

After cleaning the Si wafer, the transfer chamber 10 is released to the atmospheric pressure, and the Si wafer is loaded into the transfer chamber. The transfer chamber is approximately 1.0 × 10 _-6 Torr
After that, 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 evacuated until the degree of vacuum in the reaction chamber 2 becomes approximately 1.0 × 10 ₋₈ Torr.

In this embodiment, the first gas line is used for DMAH. DMAH
Ar was used as the carrier gas for the line. The second gas line
The third gas line for H _{2 is} for Si ₂ H ₆ .

Flow H ₂ from the second gas line and use the slow leak valve 8
Is adjusted so that the pressure in the reaction tube 2 becomes a desired value.
The typical pressure in this embodiment is approximately 1.5 Torr. Thereafter, the heater 4 is energized to heat the wafer. After the wafer temperature reaches a desired temperature, DMAH is introduced into the reaction tube from the DMAH line. The total pressure is approximately 1.5 Torr, and the DMAH partial pressure is approximately 1.5 × 10 ⁻⁵ Torr. The partial pressure of Si ₂ H ₆ is 2 × 10 ⁻⁷ Torr. When Si ₂ H ₂ and DMAH are introduced into the reaction tube 2, Al—Si is deposited. The above is the first deposition step.

After forming a continuous Al-Si film of about 100-200 ° in the first deposition step, high-speed deposition is performed in the second deposition step.

The second deposition process condition is that the total pressure is approximately 1.5 Torr and the partial pressure of DMAH is approximately 1.0 × 10 ⁻³ Torr. Si ₂ H ₆ partial pressure is 1.5 × 10 ^-5 Tor
r. DMAH and Si ₂ H ₆ after a predetermined deposition time
Stop supplying. Next, heating of the heater 4 is stopped, and the wafer is cooled. After the supply of H ₂ gas is stopped and the inside of the reaction tube is evacuated, the wafer is transferred to the transfer chamber, and only the transfer chamber is set to the atmospheric pressure, and then the wafer is taken out. The above is the outline of the Al film formation.

 Next, preparation of a sample in this embodiment will be described.

Si substrate (N type 1-2 Ωcm) was converted to hydrogen combustion system (H ₂ : 4 l / M,
(O ₂ : 2 l / M) at a temperature of 1000 ° C.

The thickness was 7000 ± 500 ° and the refractive index was 1.46. A photoresist is applied to the entire surface of the Si substrate, and a desired pattern is baked by an exposure machine. The pattern is 0.25μm ×
Various holes of 0.25 μm to 100 μm × 100 μm are formed. After developing the photoresist, the underlying SiO ₂ was etched by reactive ion etching (RIE) using the photoresist as a mask, thereby partially exposing the substrate Si.
Thus, 0.25 μm × 0.25 μm to 100 μm × 100 μm
Prepare 130 samples with SiO ₂ holes of various sizes, set the substrate temperature in 13 ways, and at each substrate temperature
At the time of the first deposition step according to the procedure described above for the ten samples, the total pressure is 1.5 Torr, the DMAH partial pressure is 1.5 × 10 ⁻⁵ Torr, and the Si ₂ H ₆ partial pressure is 2.0 × 10 ⁻⁷ Torr. An Al—Si film was deposited under the conditions of a total pressure of 1.5 Torr DMAH partial pressure of 1.0 × 10 ⁻³ Torr Si ₂ H ₆ partial pressure of 1.5 × 10 ⁻⁵ Torr.

The Al-Si film deposited by changing the substrate temperature to 13 levels was evaluated using various evaluation methods. The results were the same as in Table 1.

Al-Si is formed on SiO ₂ in the temperature range of 160 ° C. to 450 ° C. In the sample without deposition, Al-Si was deposited only on the portion where SiO ₂ is opening and Si is exposed. Note that the same selective deposition property was maintained when Al-Si was deposited at 2 μm in the above-mentioned temperature range.

When the substrate temperature in the first and second deposition steps exceeded 300 ° C., high-speed deposition of 0.5 to 1.0 μm / min was possible,
The surface reflectivity is slightly worse.

It is considered that the high temperature in the first deposition step is caused by poor flatness of the ultra-thin Al-Si film deposited in the first deposition step.

(Example 8) By the same procedure as that of Example 7, during the first deposition step, the total pressure is 1.5 Torr DMAH partial pressure 1.0 × 10 ⁻⁵ Torr Si ₂ H ₆ partial pressure 1.5 × 10 ⁻⁷ Torr Substrate temperature 270 ° C. Alternatively, at the time of the second deposition step at 300 ° C., the substrate temperature in the second deposition step is raised to 13 levels under the condition that the total pressure is 1.5 Torr, the DMAH partial pressure is 1.0 × 10 ⁻³ Torr, and the Si ₂ H ₆ partial pressure is 1.5 × 10 ⁻⁵ Torr. The results of various evaluations of the Al—Si film deposited while changing were the same as those in Table 2.

There was no difference in the results obtained when the substrate temperature in the first deposition step was 270 ° C. and 300 ° C.

As in Example 1, when the substrate temperature in the second deposition step exceeded 300 ° C., high-speed deposition of 0.5 to 1.0 μm / min was possible. The difference from Example 1 was that even when the substrate temperature in the second step was 330 ° C. or 350 ° C., an Al—Si film having a high surface flatness and a reflectivity of 80-95% could be formed.

As in Example 1, Al-Si was selectively deposited only on Si.

The selectivity was maintained even when Al-Si was deposited up to 2 μm.

(Example 9) In the same procedure as in Example 8, the total pressure is 1.5 Torr DMAH, the partial pressure is 1.0 × 10 ^-5 Torr, the substrate temperature is 270 ° C., and the total pressure is 1.5 Torr DMAH during the first deposition step. The partial pressure is 1.0 × 10 ^-3 Torr The substrate temperature is 330 ° C., and the partial pressure of Si ₂ H ₆ is 3 × 10 ^-4 of the DMAH partial pressure in each step.
The deposition was performed by changing the ratio from 2 times to 0.2 times.

The Si content (wt%) in the formed Al-Si film is 0.005%
From 5% to 5% almost in proportion to the partial pressure of Si ₂ H ₆ . With respect to resistivity, carbon content, average wiring life, deposition rate, hillock density, and generation of spikes, the same results as in Example 1 were obtained. However, in the sample having a Si content of 4% or more, a precipitate supposed to be Si was formed in the film, the surface morphology was deteriorated, and the reflectance was 65% or less. The reflectance of the sample having a Si content of less than 4% was 80 to 95%, which was the same as in Example 8. As in the case of Example 8, selective deposition by the substrate surface material was also confirmed in all regions.

(Example 10) In the same procedure as in Example 7, only the carrier gas of DMAH was changed to H _2.
, But _Ar, and Al-Si deposition was performed.

From the second gas line, and supplies the H _2.

The obtained results were 160 ° C. to 4 ° C. as in Table 1 of Example 1.
Al-Si does not deposit on SiO ₂ in the temperature range of 50 ° C,
Al-Si was deposited only in portions where SiO ₂ was opened and Si was exposed. Note that the same selective deposition property was maintained when Al-Si was deposited at 2 μm in the above-mentioned temperature range.

When the substrate temperature in the first and second deposition steps exceeded 300 ° C., high-speed deposition of 0.5 to 1.0 μm / min was possible,
The surface reflectivity is slightly worse.

It is considered that the high temperature in the first deposition step is caused by poor flatness of the ultra-thin Al-Si film deposited in the first deposition step.

The same procedure as Example 11 Example 8, the carrier gas of DMAH only H ₂
Instead, Ar was used, and Al—Si deposition was performed.

The second gas line was supplied H _2.

When the substrate temperature in the first deposition step was 270 ° C. or 300 ° C., there was no difference in the obtained results. The obtained film quality is almost the same as in Table 2.

As in the case of Example 7 or Example 8, when the substrate temperature in the second deposition step exceeds 300 ° C, 0.5 to 1.
High-speed deposition of 0 μm / min was possible. The difference from Examples 7 and 8 is that the substrate temperature in the second step was 330 ° C., 35 ° C.
The point is that even at 0 ° C., an Al—Si film having a high surface flatness having a reflectance of 80 to 95% was formed.

As in Example 7 and Example 8, Al-Si was selectively deposited only on Si. The selectivity was maintained even when Al-Si was deposited at 2 m.

(Example 12) In the same procedure as in Example 9, only the carrier gas of DMAH was changed to H _2.
Instead, Ar was used, and Al—Si deposition was performed.

The second gas line was supplied H _2.

 The deposition conditions are as follows.

In the first deposition step, the total pressure is 1.5 Torr, the partial pressure of DMAH is 1.0 × 10 ⁻⁵ Torr, and the substrate temperature is 270 ° C. In the second deposition step, the total pressure is 1.5 Torr, the partial pressure of DMAH is 1.0 × 10 ⁻³ Torr, and the substrate temperature is 330 ° C. The Si ₂ H ₆ partial pressure was set to 3 × 10 ^-4 of the DMAH partial pressure in each process.
The deposition was carried out by changing from 2 times to 0.2 times.

As in Example 9, the Si content (wt%) in the formed Al-Si film changed from 0.005% to 5% almost in proportion to the Si ₂ H ₆ partial pressure. Example 1 concerning resistivity, carbon content, average wiring life, deposition rate, hillock density, and spike generation
The same result was obtained. However, in the sample having a Si content of 4% or more, a precipitate supposed to be Si was formed in the film, the surface morphology was deteriorated, and the reflectance was 65% or less. The reflectance of the sample having a Si content of less than 4% was 80 to 95%, which was the same as in Example 8. As in the case of Example 7, the selective deposition by the substrate surface material was also confirmed in all regions.

(Example 13) Using a low-pressure CVD apparatus shown in FIG. 3, a substrate (samples 5-1 to 5-179) having the following configuration was formed on Al-Si.
A film was formed.

Preparation of Sample 5-1 A thermally oxidized SiO ₂ film as a non-electron-donating second substrate surface material was formed on a single-crystal silicon as an electron-donating first substrate surface material. Patterning was performed by a photolithography process as shown in Example 7 to partially expose the single crystal silicon surface.

At this time, the thickness of the thermally oxidized SiO ₂ film was 7000 °, and the size of the exposed portion of the single crystal silicon, that is, the size of the opening was 3 μm × 3 μm. Thus, Sample 5-1 was prepared. (Hereinafter, such a sample is referred to as “thermally oxidized SiO ₂ (hereinafter abbreviated as T-SiO ₂ ) / single-crystal silicon”).

Preparation of Samples 5-2 to 5-179 Sample 5-2 was an oxide film (hereinafter abbreviated as SiO ₂ ) formed by normal pressure CVD / single crystal silicon Sample 5-3 was boron doped by normal pressure CVD Oxide film (hereinafter abbreviated as BSG) / single-crystal silicon, Sample 5-4 is phosphorus-doped oxide film (hereinafter abbreviated as PSG) / single-crystal silicon formed by atmospheric pressure CVD, Sample 5-5 is an atmospheric pressure CVD Sample 5-6 is a phosphorous and boron doped oxide film (hereinafter abbreviated as BSPG) / single crystal silicon. Sample 5-6 is a nitride film (hereinafter abbreviated as PS: N) / single crystal silicon formed by plasma CVD. Sample 5 -7 is a thermal nitride film (hereinafter abbreviated as TS: N) /
Sample 5-8 is a nitride film (hereinafter abbreviated as LP-S: N) / monocrystalline silicon formed by low-pressure DCVD. Sample 5-9 is a nitride film (hereinafter ECR-SiN) formed by an ECR device. Abbreviation) / single-crystal silicon. Further, Samples 5-11 to 5-179 shown in Table 3 were prepared by combining the first substrate surface material having an electron donating property and the second substrate surface material having a non-electron donating property. Single-crystal silicon (single-crystal Si), polycrystalline silicon (polycrystalline Si), amorphous silicon (amorphous Si), tungsten (W), molybdenum (Mo), tantalum (T
a), tungsten silicide (WSi), titanium silicide (TiSi), aluminum (Al), aluminum silicon (Al-Si), titanium aluminum (Ai-Ti), titanium nitride (Ti-N), copper (Cu), Aluminum silicon copper (Al-Si-Cu), aluminum palladium (Al-
Pd), titanium (Ti), molybdenum silicide (Mo-S
i), tantalum silicide (Ta-Si) was used. These samples were placed in the reduced pressure CVD apparatus shown in FIG. 3, and an Al—Si film was formed in the same badge.

 The deposition conditions are as follows.

During the first deposition step, total pressure 0.3 Torr DMAH partial pressure 3 × 10 ^-6 Torr Si ₂ H ₆ partial pressure 1.0 × 10 ^-7 Torr Substrate temperature 270 ° C. During the second deposition step, total pressure 0.3 Torr DMAH partial pressure 1 × 10 ⁻⁴ Torr Si ₂ H ₆ partial pressure 3 × 10 ⁻⁶ Torr The substrate temperature is 330 ° C.

As a result of forming a film under these conditions, in all of the samples 5-1 to 5-179 subjected to patterning, deposition of Al-Si occurs only on the surface of the electron-donating first substrate, and an opening of 7000 ° The part was completely filled. The properties of the Al-Si film are not different from those in Table 2 where the substrate temperature in the second deposition step is 330 ° C., and the deposition rate in the second deposition step is approximately 0.7 μm / Minutes were very fast.

Example 14 An Al—Si film was deposited using MMAH ₂ instead of DMAH in the same procedure as in Example 8.

As the substrate, a Si wafer patterned with the SiO ₂ thin film shown in Example 7 was used.

 The deposition process conditions are as follows.

During the first deposition step, the reaction tube pressure is 1.5 Torr MMAH ₂ partial pressure 5.0 × 10 ^-5 Torr Si ₂ H ₆ partial pressure 1.0 × 10 ^-6 Torr Base temperature 270 ° C. During the second deposition step, the reaction tube pressure is 1.5 Torr MMAH ₂ partial pressure 1 × 10 ⁻³ Torr Si ₂ H ₆ partial pressure 1.0 × 10 ⁻⁵ Torr.

As in Example 8, the Al-Si film can fill the opening of SiO ₂ at 7000 °, and the film quality of Al-Si is different from that of the second deposition step shown in Table 2 where the substrate temperature is 330 ° C. There was no.

In addition, the deposition rate of Al-Si in the second deposition step is approximately 0.1.
There was no difference from 7 μm / min when DMAH was used.

(Example 15) Example 8 the same procedure was carried out deposition of Al-Si film by using SiH ₄ instead of Si ₂ H _6.

The substrate used was the Si wafer shown in Example 1 on which the SiO ₂ thin film was patterned.

 The deposition conditions are as follows.

During the first deposition step, the reaction tube pressure is 1.5 Torr DMAH partial pressure 1.0 × 10 ^-5 Torr Si ₂ H ₆ partial pressure 5.0 × 10 ^-7 Torr Substrate temperature 270 ° C. During the second deposition step, the reaction tube pressure is 1.5 Torr DMAH Partial pressure 1.0 × 10 ⁻³ Torr Si ₂ H ₆ partial pressure 5.0 × 10 ⁻⁵ Torr The substrate temperature is 330 ° C.

As in Example 8, the Al-Si film can fill the opening of SiO ₂ at 7000 °, and the film quality of Al-Si is the same as that of the substrate temperature of 330 ° C. in the second deposition step in Table 2. There were no differences.

In addition, the deposition rate of Al-Si in the second deposition step is approximately 0.1.
There was no difference from the case of using Si ₂ H ₆ which was as large as 7 μm / min.

(Example 16) A sample in which an Al film was formed by the same method as in Example 1 was prepared. The crystallinity of the Al film selectively deposited on Si at the same substrate temperature as in Table 1 was determined by X-ray diffraction and scanning μ-RHEED.
Evaluation was performed using a microscope.

Scanning μ-RHEED microscopes use Extended Abstracts of t
he 21th Conference on Solid State Devices and Mate
rials (1989) p.217 and Japanese Journal of Applie
d Physics vol.28.No.11 (1989 L2075.). Conventional RHEED (Reflection High Energy El
In the ectron diffraction (reflection high-speed electron beam diffraction) method, an electron beam is incident on the sample surface at a shallow angle of 2 to 3 °, and the crystallinity of the sample surface is evaluated from a diffraction pattern generated by the diffracted electron beam. However, the electron beam diameter is
Since it is between 100 μm and several hundred μm, only average information on the surface of the material could be obtained. The scanning μ-RHEED microscope can observe an electron beam diffraction pattern from a specific minute area on the sample surface by narrowing the electron beam diameter to 0.1 μm. In addition, an electron beam is two-dimensionally scanned on the surface of the material, and a change in the intensity of the diffraction spot on the diffraction pattern is used as an image signal, and a two-dimensional image of the material surface due to the change in the intensity of the diffraction spot (scanning μ-RHEED Image) can be obtained. At this time, when a scanning μ-RHEED image using different diffraction spots A and C on the diffraction pattern is observed as shown in FIG. 4, even if the lattice plane parallel to the sample surface is aligned with (100), for example, In the plane, rotating crystal grain boundaries can be distinguished and imaged. Here, the diffraction spot A is a diffraction spot on a line (line 1) where a plane where a diffraction pattern is generated and a sagittal plane formed by an incident electron beam are orthogonal, and a diffraction spot C
Are diffraction spots not on line l. As shown in FIG.
If the lattice plane parallel to the sample surface is, for example, (100), but the crystal grains x and y rotate in plane with each other,
In the scanning μ-RHEED image using the diffraction spot A, both the crystal grains x and y are displayed as regions with high intensity. On the other hand, in the scanning μ-RHEED image using the diffraction spot C, only the crystal grain x is displayed as a region having a high intensity. Therefore, scanning μ-RHEE using diffraction spots A and C as shown in FIG.
By observing the D image, it is possible to identify whether the crystal in the observation region is a polycrystal including in-plane rotation or a single crystal. Extended Abstracts of the 21th Confe shown earlier
rence on Solid State Devices and Materials (1989)
p.217 and Japanese Journal of Applied Physics vo
In l.28.No.11 (1989 L2075.), for a Cu thin film, for example, even if the lattice plane parallel to the sample surface is {100},
It is clear that crystal grains including in-plane rotation exist in the 0 ° crystal grains.

First, the Al film selectively deposited on the exposed Si surface at the substrate temperature shown in Table 1 was evaluated.

When the crystal orientation of the surface of the Si substrate is the (111) plane, as shown in FIG.
Only the diffraction peak indicating 0) was observed. Next, the crystallinity of the selectively deposited Al film was evaluated using a scanning μ-RHEED microscope. As shown in FIG. 7, after a region where Al is selectively deposited is identified by a scanning secondary electron image (FIG. 7 (a)) showing a surface shape, a [001] direction is applied to the Al (100) plane. Diffraction spots 200 (corresponding to diffraction spot A in FIG. 4) and diffraction spots 6 on the diffraction pattern generated when an electron beam is incident from FIG.
Scan μ-RHEE using 20 (corresponding to diffraction spot C in FIG. 4)
D images (FIGS. 7 (b) and 7 (c)) were observed.
As shown schematically in FIGS. 7 (b) and (c), there is no change in brightness on the selectively deposited Al film, and the selectively deposited Al is an Al (100) single crystal. Was confirmed.

When the exposed surface of the Si was not linear but was a via hole, the Al which was selectively deposited regardless of the diameter of the via hole was also an AL (100) single crystal. When the substrate temperature range was from 250 ° C. to 330 ° C., the selectively deposited Al became a single crystal.

Also, the Si (111) plane is 1 °, 2 °, 3 °
°, 4 °, 5 ° Al films selectively deposited on off-angle Si (111) substrates differ in temperature from 250 ° C. to 330 ° C. as in the case of deposition on Si (111) substrates. Under this temperature condition, an Al (100) single crystal was deposited.

When the crystal orientation of the surface of the Si base is the (100) plane, the X-ray diffraction shows that, as shown in FIG.
Only a diffraction peak indicating (111) was observed. Ninth
The figure shows the scanning secondary electron image when Al is selectively deposited only on the exposed surface of Si on the substrate where SiO ₂ is patterned in a line shape and Si (100) is exposed in a line shape (FIG. 9 (a) ) And scanning μ-RHEED images (FIGS. 9 (b) and (c)). Scanning μ-RHEED images used 333 diffraction spots (FIG. 9B) and 531 diffraction spots (FIG. 9C). It was confirmed that the selectively deposited Al film was an Al (111) single crystal. When the substrate temperature was in the range of 250 ° C. to 330 ° C., the selectively deposited Al film became a single crystal.

Also, the Si (100) plane is 1 °, 2 °, 3 °
°, 4 °, 5 ° Al films selectively deposited on different off-angle Si (100) substrates also have a substrate temperature in the range of 250 ° C. to 330 ° C., similarly to the case where the Al film is deposited on the Si (111) substrate. Under these temperature conditions, an Al (111) single crystal was deposited.

(Example 17) The crystallinity of the Al film selectively deposited on the exposed Si surface by the method shown in Example 2 was evaluated using an X-ray diffraction method and a scanning μ-RHEED microscope. there were.

When the crystal orientation of the Si substrate surface was the (111) plane, only a diffraction peak indicating Al (100) was observed from the X-ray diffraction, as shown in FIG. When the selectively deposited Al film was observed with a scanning μ-RHEED microscope, it was found to be an Al (100) single crystal as in Example 1.

Also, the Si (111) plane is 1 °, 2 °, 3 °
The Al film deposited on the off-angle Si (111) substrate at different angles of 4 °, 4 °, and 5 ° also has the first and second substrate temperatures of 250 ° C. to 330 ° C., similarly to the case where the Al film is deposited on the Si (111) substrate. ° C
Under the temperature conditions in the range, an Al (100) single crystal was deposited.

When the crystal orientation of the surface of the Si base is the (100) plane, the X-ray diffraction shows that, as shown in FIG.
Only a diffraction peak indicating (111) was observed. When the selectively deposited Al film was observed with a scanning μ-RHEED microscope, it was found to be an Al (100) single crystal as in Example 1.

In the second substrate temperature range shown in Table 2, the substrate temperature was 270 ° C.
In the temperature range from to 330 ° C., the deposited Al film became a single crystal.

Also, the Si (100) plane is 1 °, 2 °, 3 °
The Al film deposited on the off-angle Si (100) substrate having different off-angles of 4 ° and 4 ° also has a second substrate temperature in the range of 270 ° C. to 330 ° C., similarly to the case where the Al film is deposited on the Si (111) substrate. Under these temperature conditions, an Al (111) single crystal was deposited.

(Example 18) The crystallinity of an Al film selectively deposited by the method of Example 3 was evaluated. As in the case of the first embodiment, the first and second
Under the temperature condition of the substrate temperature of 250 ° C. to 330 ° C., Si
An Al (100) single crystal was deposited on the (111) substrate, and an Al (111) single crystal was deposited on the Si (100) substrate.

Example 19 The crystallinity of an Al film selectively deposited by the method of Example 4 was examined. As in the case of Example 1, when the second substrate temperature in Table 2 is in the range of 270 ° C. to 330 ° C., Al (100) single crystal on the Si (111) substrate and Al on the Si (100) substrate (11
1) Single crystals were deposited.

(Example 20) The crystallinity of the Al film selectively deposited by the LP-CVD method shown in Example 5 was as follows.

From the scanning μ-RHEED microscopic observation by the same observation method as in Example 16, when the first base material was Si (111),
The second base material is T-SiO ₂ , SiO ₂ , BSG, PSG, BPSG, P-Si
In each of the cases of N, T-SiN, LP-SiN, and ECR-SiN, Al selectively deposited was Al (100). When the first base material is Si (100), the second base material is T-Si
O ₂ , SiO ₂ , BSG, PSG, BPSG, P-SiN, T-SiN, LP-SiN, ECR-S
In each case of iN, the selectively deposited Al film is Al (111)
Met.

When the first substrate material is TiN, the second substrate material is _{T-SiO 2, SiO 2,} BSG, PSG, BPSG, P-SiN, T-SiN, LP-SiN,
In each case of ECR-SiN, the selectively deposited Al film is oriented to Al (111) by X-ray diffraction measurement, and conventional reflection high-speed electron diffraction using an electron beam with an acceleration voltage of 80 kV or 100 kV. From the pattern observation, diffraction spots relating to Al (111) were strongly observed.

[Effects of the Invention] As described above, according to the present invention, a low-resistance, dense, and flat Al or Al-Si film can be selectively and rapidly deposited on a substrate.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an element for film formation in a deposited film forming method according to the present invention, FIG. 2 is a schematic view showing an example of a deposited film forming apparatus to which the present invention can be applied, and FIG. FIG. 4 is a schematic diagram illustrating another example of a possible deposited film forming apparatus, FIG. 4 is a schematic diagram illustrating a scanning μ-RHEED, FIG. 5 is a schematic diagram illustrating the results of crystal grain observation using a scanning μ-RHEED image, FIG. 6 is an X-ray diffraction pattern on a Si (111) substrate, FIG. 7 is a diagram showing a scanning secondary electron image and a scanning μ-RHEED image of an Al film selectively deposited on the Si (111) substrate, FIG. 8 shows an X-ray diffraction pattern on a Si (100) substrate, and FIG. 9 shows a scanning secondary electron image and a scanning μ-RHEED image of an Al film selectively deposited on the Si (100) substrate. . DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Reaction tube, 3 ... Substrate holder, 4 ... Heater,
5: Mixer, 6: Vaporizer, 7: Gate valve, 8: Slow leak valve, 9: Exhaust unit, 10: Transfer chamber, 11 ...
Valve, 12 ... exhaust unit, 50 ... quartz outer reaction tube, 51
... Inner reaction tube made of quartz, 52 ... Source gas inlet, 53 ... Gas exhaust outlet, 54 ... Metal flange, 56 ... Base holder, 57 ... Base, 58 ... Gas flow, 59 ... Heater section.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location H01L 21/285 301 H01L 21/285 301M 21/3205 21/88 N

Claims (10)

(57) [Claims] In a method of forming a film mainly composed of aluminum by a thermal CVD method, a substrate having an electron donating surface (A) and a non-electron donating surface (B) is deposited. Disposing in a space for forming a film, introducing an alkyl aluminum hydride gas and hydrogen gas into the space for forming a deposited film, and within a temperature range not lower than the decomposition temperature of the alkyl aluminum hydride and not higher than 450 ° C. Maintaining the electron donating surface (A) and changing the temperature so as to lower the temperature in the early stage of film formation and then increase it, or to lower the partial pressure of alkyl aluminum hydride and then increase it in the early stage of film formation. The deposition rate of aluminum is changed by at least one of changing the partial pressure to change the aluminum film. The deposited film forming method characterized by comprising the step of selectively forming a donative surface (A). 2. The method according to claim 1, wherein said alkyl aluminum hydride is dimethyl aluminum hydride. 3. The method according to claim 1, wherein said alkyl aluminum hydride is monomethyl aluminum hydride. 4. The method according to claim 1, wherein the electron donating surface is a metal or a silicide thereof. 5. An electron donating surface comprising: tungsten;
Molybdenum, tantalum, tungsten silicide, titanium silicide, aluminum, aluminum silicon,
Titanium aluminum, titanium nitride, copper, aluminum silicon copper, aluminum palladium, titanium,
The method according to claim 1, wherein the method is selected from molybdenum silicide and tantalum silicide. 6. A deposition film forming method for forming a film containing aluminum as a main component by a thermal CVD method, wherein a substrate having an electron donating surface (A) and a non-electron donating surface (B) is deposited. Disposing in a space for forming a film, introducing an alkyl aluminum hydride gas and a gas containing silicon and hydrogen gas into the space for forming a deposited film, and 450 ° C. or higher, which is higher than the decomposition temperature of the alkyl aluminum hydride. Maintaining the electron donating surface (A) within the following range, and changing the temperature so as to lower the temperature in the early stage of film formation and then increase it, or to reduce the partial pressure of the alkyl aluminum hydride in the early stage of film formation. By changing the partial pressure to lower and then increase, the aluminum containing silicon is deposited. The deposited film forming method characterized by comprising the step of selectively forming by changing the rate of aluminum film containing silicon on electron donative surface (A). 7. The method according to claim 6, wherein the alkyl aluminum hydride is dimethyl aluminum hydride. 8. The method according to claim 6, wherein the alkyl aluminum hydride is monomethyl aluminum hydride. 9. The method according to claim 6, wherein the electron donating surface is a surface of a metal or a silicide thereof. 10. An electron donating surface comprising: tungsten, molybdenum, tantalum, tungsten silicide,
The method according to claim 6, wherein the method is selected from titanium silicide, aluminum, aluminum silicon, titanium aluminum, titanium nitride, copper, aluminum silicon copper, aluminum palladium, titanium, molybdenum silicide, and tantalum silicide.