JPH09246211A - Vapor deposition of conductive thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform pretreatment of a substrate by a method of high safety without increasing the size of the manufacturing apparatus and specializing the apparatus by supplying organic metal gas containing halogen for surface treatment of the conductive region before performing vapor deposition of a conductive thin film on a conductive region provided on a substrate. SOLUTION: Before vapor deposition of a conductive thin film on a conductive region 3 provided in a substrate 1, organic mental gas 4 containing halogen is supplied so as to perform surface treatment of the conductive region 3. Or, in a vapor deposition process of the conductive thin film 6 on the conductive region 3 provided in a substrate 1, the organic metal gas 4 containing halogen together with a material gas 5 of the conductive thin film 6 is supplied so as to treat the surface of the conductive region 3. For instance, the conductive thin film 6 to be Al, the material gas 5 is top be Al(CH3 )2 H or the like, organic metal gas 4 containing halogen is to be Al(C2 H5 )2 Cl or the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vapor phase growth method for conductive thin films, and more particularly to a vapor phase growth method (CVD).
Method), which is characterized in pretreatment for enabling the growth of a high-quality conductive thin film for wirings and electrodes.

[0002]

2. Description of the Related Art In recent years, as semiconductor devices have been miniaturized to achieve higher speeds and higher integration, there has been a demand for a technique for producing highly reliable wiring layers or electrodes of sub-micron or smaller size. It has been proposed to use a CVD method using an organic metal instead of the method.

As described above, when a conductive thin film to be a wiring layer or an electrode is grown by the CVD method, plasma of a reactive gas containing halogen such as F and Cl is used as a substrate pretreatment. The surface of the silicon substrate exposed in the contact hole and the surface of the wiring layer exposed in the via hole are processed to remove the natural oxide film and the like.

This is because if a natural oxide film remains on the growth surface, a part that easily grows and a part that does not grow easily are mixed, and uniform initial growth cannot be performed. This is because the deterioration or deterioration of the surface morphology occurs.

As another substrate processing method, a ClF ₃ gas at 100 ° C. is supplied to the reaction chamber to perform pretreatment by a plasmaless reaction, and then CVD is performed in the same reaction chamber.
It has been proposed to grow an Al film by the method, and ClF ₃ has excellent etching selectivity between the TiN film and the BPSG film, and the improved specular reflectance of the grown Al film, that is, It has been reported that the surface morphology of the Al film is improved (if necessary, Hideki Matsuhashi et al., 1
Spring 995, 42nd Joint Lecture on Applied Physics, Proceedings, No. 2, p. 733, 29p-K-9).

As described above, when a conductive film such as an Al film is formed by a CVD method using an organic metal, the growth of Al depends on the underlying layer, preferentially grows on the conductive film, and on the oxide film. Since it is difficult for the Al film to grow, the selective growth of the Al film is increased by cleaning the underlayer surface by pretreatment, and since the natural oxide film and the like are not locally left, the growth of the Al film with improved surface morphology can be achieved. It will be possible.

[0007]

However, when plasma is used for the substrate pretreatment, it is necessary to provide a dedicated pretreatment chamber, and there is a problem that the apparatus becomes bulky.
Further, there is a problem that the substrate surface is damaged by ion bombardment by exposing the substrate to plasma.

Further, when ClF ₃ is used, it does not require a dedicated pretreatment chamber because it is plasmaless.
Since ClF ₃ is a highly corrosive gas, it is handled in a high-pressure gas cylinder container even though it is 0.5 atm at room temperature, and there is a problem that it is subject to regulations by local governments. Because it is highly corrosive,
Corrosion resistance treatment and exhaust gas treatment of the reactor become a problem, and it requires careful handling.

Therefore, it is an object of the present invention to pretreat a substrate by a highly safe method when growing a conductive thin film to be a wiring layer or an electrode without increasing the size or specializing the device. To do.

[0010]

FIG. 1 is an explanatory view of the principle configuration of the present invention, and means for solving the problems in the present invention will be described with reference to FIG. 1 (a) and 1 (b) (1) The present invention relates to a vapor phase growth method of a conductive thin film,
It is characterized in that the organic metal gas 4 containing halogen is supplied to treat the surface of the conductive region 3 before vapor-depositing the conductive thin film 6 on the conductive region 3 provided on the substrate 1.

Since the organometallic gas 4 containing halogen has reactivity and high safety, the conventional MO gas is not used.
Using the VPE device (organic metal vapor phase growth device) as it is, the surface of the conductive region 3 provided on the substrate 1 can be treated by simple handling.

(2) Further, in the vapor phase growth method of the conductive thin film 6, the present invention is characterized in that in the step of vapor phase growing the conductive thin film 6 on the conductive region 3 provided on the substrate 1, the conductive thin film 6 is formed. The organometallic gas 4 containing halogen is supplied together with the raw material gas 5 of 1. to treat the surface of the conductive region 3.

As described above, the organic metal gas 4 containing halogen, that is, the etching gas and the source gas 5 for the conductive thin film 6 are simultaneously supplied to etch the conductive region 3 provided on the substrate 1 by etching. It is also possible to grow the conductive thin film 6 while cleaning, and in particular, when growing the conductive thin film 6 on the surface of the conductive region 3 exposed in the via hole provided in the interlayer insulating film, the conductivity deposited on the surface of the interlayer insulating film. Since the deposition rate of the conductive thin film 6 is low, the etching action is predominant, and the conductive thin film 6 is deposited only on the conductive region 3.

(3) Further, in the present invention, in the above (1) or (2), the halogen-containing organometallic gas 4 contains at least one of the metal elements constituting the conductive thin film 6. Characterize.

Organometallic gas 4 containing such a halogen
Is safer than ClF _{3 and the} like, and contains at least one of the metal elements that form the conductive thin film 6, so that an organic metal gas containing halogen in the MOVPE device during deposition of the conductive thin film 6 Conductive thin film 6 even if 4 remains
The conductive thin film 6 without affecting the composition of
When the raw material gas 5 is simultaneously supplied, the composition of the conductive thin film 6 to be deposited can be stabilized.

(4) Further, the present invention is characterized in that in any of the above (1) to (3), the conductive thin film 6 is either Al or an Al alloy containing Al as a main component. To do.

As a material for forming such a wiring layer, A
An Al alloy containing 1 or Al as a main component is typical.

[0018] (5) Further, the present invention, the above (1) to (4) in any of the organometallic gas 4 containing halogen, the R C _x H _y, R 'and C _x' H _y ' And then A
lR _u R ′ _v Cl _w F _z (where u, v, w and z are integers and u + v + w + z = 3).

Thus, the organometallic gas containing halogen 4
AlR as _{u R 'v Cl w F z} , i.e., the raw material of the organic Al gas containing a halogen, the number Torr~ tens T at room temperature
Since it has a vapor pressure of about orr and is low in corrosiveness and toxicity, it is easy to handle and treat the exhaust gas, and the Al-CVD apparatus, that is, the MOVPE apparatus can be used as it is.

(6) Further, in the present invention according to the above (5), u = 2, v = 0, w = 1 and z = 0, or
One of u = 2, v = 0, w = 0, and z = 1.

Thus, the organometallic gas 4 containing halogen
Is an Al element in which the halogen element is 1 and R is 2.
_{R u R 'v Cl w F} z is the most readily available, and, the handling is simple.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION First, a schematic structure of a vapor phase growth apparatus (MOVPE apparatus) used for carrying out the present invention will be described with reference to FIG. See FIG. 2. This vapor phase growth apparatus comprises an organometallic gas supply system and a reaction chamber system. First, Al (C) for growing an Al layer is used.
H ₃ ) ₂ H, that is, the DMAH supply system monitors the vessel 11 containing the DMAH 12, the MFC (mass flow controller) 13 supplying hydrogen gas for bubbling the DMAH 12, and the pressure gauge 15 for the pressure of the vaporized DMAH gas. Pressure control valve 16, D for adjusting the pressure by
An MFC 14 that supplies hydrogen gas for transporting MAH gas while adjusting the flow rate, a valve 17 that switches to an exhaust system (vent) when DMAH gas is not needed, a case where DMAH gas is not used, for example, Al (C ₂ H ₅ ) ₂ Cl, that is, when the DEAC gas is supplied to clean the surface of the semiconductor substrate 32, the MFC 19 and the valve 18 for supplying the hydrogen gas for adjusting the balance of the total flow rate are provided. Chamber 3 which constitutes a reaction chamber system via
0 is supplied.

The configuration of the DEAC supply system is also DMAH.
The configuration is substantially the same as that of the supply system, in which the DMAH 11 in the DMAH supply system is replaced with the DEAC 22, and similarly, the DMAH 11 is supplied to the chamber 30 which constitutes the reaction chamber system via the pipe 20.

The reaction chamber system includes a chamber 30, a carbon susceptor 31 for holding and fixing the semiconductor substrate 32 provided in the chamber 30, an RF coil 33 for heating the semiconductor substrate 32, and introduced gas and reaction. It is composed of an exhaust port 34 for exhausting the product.

When the substrate pretreatment is performed in such a vapor phase growth apparatus, the valve 27 supplies the DEAC gas to the pipe 20, and the valve 17 switches the DMAH gas to the exhaust system (vent). , An Al film is deposited, the valve 27 switches the DEAC gas to the exhaust system (vent), and the valve 17 controls the DM gas.
AH gas is supplied to the pipe 20.

Further, when the Al film is grown while supplying the DEAC gas, the valve 17 and the valve 27 are both connected to the pipe 2
The DEAC gas and the DMAH gas may be simultaneously supplied into the chamber 30 by switching to the 0 side.

Next, a first embodiment of the present invention will be described with reference to FIG. See FIG. 3A. First, a base insulating film made of an SOG (spin on glass) film 42 is provided on a silicon substrate 41, and then a TiN film 43 serving as a barrier metal is deposited on the entire surface by a sputtering method. Using the vapor phase growth apparatus shown, the temperature of the container 21 is set to 10 to 50 ° C., for example, 20 ° C., and the H ₂ gas supplied from the MFC 23 is 100 to 10 ° C.
The pressure in the chamber 30 is controlled to 10 sccm, for example, 400 sccm.
The substrate temperature is 200 to
The natural oxide film formed on the surface of the TiN film 43 is removed by performing a treatment for 10 to 600 seconds, for example, 60 seconds in the DEAC gas 44 atmosphere under the condition of 300 ° C., for example, 300 ° C.

In this case, AES (Auger electron spectroscopy)
When the surface of the TiN film 43 after the DEAC process is measured by the method, the Al deposited on the surface of the TiN film 43 after that is measured.
-Cl that becomes a factor that deteriorates the surface morphology of the CVD film
It was confirmed that no exist.

Next, referring to FIG. 3B, the introduced gas is switched to DMAH, the temperature of the container 11 is set to 0 to 50 ° C., for example, 20 ° C., and the H ₂ gas supplied from the MFC 13 is 10 to 2000 sccm, for example. The pressure in the chamber 30 is 10 to 3000 Pa, for example, 2 sccm.
70 Pa, the substrate temperature is 100 to 400 ° C., for example,
1 in a DMAH gas 45 atmosphere at 200 ° C.
The Al layer 46 having a thickness of 30 to 1000 nm is deposited by processing for 60 minutes, for example, 10 minutes, and patterned to form a wiring layer. Before patterning, a TiN film may be provided on the Al layer 46 as an antireflection film and a barrier metal by a sputtering method.

In this case, the natural oxide film locally formed on the surface of the TiN film 43 has been removed by the pretreatment by DEAC, and since Cl does not exist on the surface of the TiN film 43, the surface of the TiN film 43 is not removed. The Al layer 46 grows uniformly, and the height difference of the unevenness on the surface is 400 Å (40
Since the surface morphology is significantly improved, the patterning accuracy using the photolithography process is improved, and the wiring layer of submicron or less can be patterned with high accuracy.

As described above, in the present invention, since the DEAC having low corrosiveness is used and the plasma reaction is not used, a dedicated pretreatment chamber becomes unnecessary, and the conventional MOVPE apparatus can be used as it is. Therefore, the manufacturing cost can be reduced.

Next, a second embodiment of the present invention will be described with reference to FIG. See FIG. 4A. First, the TiN film 53 / Al layer 54 / TiN film 55 is formed on the silicon substrate 51 through the underlying insulating film made of the SOG film 52 by the same process as in the first embodiment.
After providing a conductive film layer having a layered structure and forming a wiring layer by patterning, an interlayer insulating layer made of a SiO ₂ film 56 is provided on the wiring layer.

Next, a via hole 57 is formed in the SiO ₂ film 56 in order to make a contact with a wiring layer for making a multilayer wiring, and then the DEAC of the first embodiment is formed.
Similar to the treatment, the temperature of the container 21 is set to 10 to 50 ° C., for example, 20 ° C., and the H ₂ gas supplied from the MFC 23 is 100 to 1000 sccm, for example, 400 sccc.
The pressure in the chamber 30 is 10 to 3000 Pa, for example, 270 Pa, and the substrate temperature is 200 to 300 ° C., for example, 300 ° C. in the DEAC gas 58 atmosphere. After being processed for 600 seconds, for example, 60 seconds, T exposed in the via hole 57
The natural oxide film formed on the surface of the iN film 55 is removed.

Next, referring to FIG. 4B, the introduced gas is switched to DMAH, the temperature of the container 11 is set to 0 to 50 ° C., for example, 20 ° C., and the H ₂ gas supplied from the MFC 13 is 10 to 2000 sccm, for example. The pressure in the chamber 30 is 10 to 3000 Pa, for example, 2 sccm.
70 Pa, the substrate temperature is 100 to 400 ° C., for example,
Al is deposited from the DMAH gas 59 under the condition of 200 ° C.

In this case, Al hardly grows on the insulating film and preferentially grows on the conductive region. However, the natural oxide film formed on the surface of the TiN film 55 exposed in the via hole 57 is not formed. Since it has been removed by the pretreatment by DEAC, the growth preferentially occurs in the via hole 57 and the Al plug 60 is formed.

Therefore, even if the diameter of the via hole 57 becomes smaller due to the miniaturization of the wiring layer, the Al plug 60 can be embedded with sufficient contactability, and a connection failure or the like due to insufficient embedding of Al occurs. Will be prevented.

Next, although not shown, as in the first embodiment, a TiN film / Al layer / TiN film 3 is formed.
By depositing and patterning a conductive film having a layered structure, the TiN film 53 / Al layer 5 is formed through the Al plug 60.
The upper wiring layer connected to the lower wiring layer made of the 4 / TiN film 55 may be formed, and thereafter, the same steps may be repeated depending on the required number of wiring layers.

In the second embodiment, since an unnecessary growth on the insulating film does not occur, a removal process such as an etch-back process is unnecessary, and even if it grows to some extent, the etch-back time is shortened. Therefore, the throughput can be improved and the manufacturing cost can be reduced.

In the description of each of the above embodiments, after the DEAC process is performed, MDAH is used to remove Al.
Although the layer is grown, the DEAC gas and the DMAH gas may be simultaneously supplied to the chamber 30 to grow the Al layer.

In this case, the etching of the natural oxide film and the conductive thin film by the DEAC gas and the film formation by the DMAH gas are carried out at the same time, but the film formation is predominant by controlling the flow rate ratio of both. It is sufficient to form a film on the exposed portion of the TiN film where Al deposition preferentially occurs, and the etching becomes dominant on the surface of the insulating film where Al deposition does not originally occur. Without this, a pure plug-like buried conductive layer can be formed.

Further, in the above description of each embodiment, the removal of the natural oxide film formed on the surface of the TiN film is targeted, but the present invention is limited to the removal of the natural oxide film on the surface of the TiN film. The present invention is also applicable to the case where an ohmic electrode is formed in a semiconductor region exposed through a contact hole.

That is, since DEAC is a gas that does not etch the SiO ₂ film but etches Si, DEAC treatment is performed after a contact hole is formed in the underlying insulating layer or the interlayer insulating film. The silicon surface exposed in the hole is etched, the natural oxide film of silicon formed on the exposed surface is removed by this etching, and an ohmic electrode such as an Al alloy can be surely buried inside the contact hole.

When the ohmic electrode is provided through the contact hole, a TiN film is provided on the entire surface as a barrier metal, DEAC is performed, and then DMA is performed.
The ohmic electrode and the wiring layer connected to the ohmic electrode may be simultaneously formed by growing an Al layer using H and patterning it.

In the above description of the embodiment, DEAC is used in the substrate pretreatment process.
Not limited to DEAC, but Al (CH ₃ ) ₂ C
1, Al (CH ₃ ) ₂ F, or Al (C ₂ H ₅ ) ₂
May be used F, furthermore, the R C _x H _y, the R 'C
_x 'H _y', i.e., an alkyl group, a vinyl group, or, when a phenyl _{group, AlR u R 'v Cl w} F z ( where
u, v, w, z are integers, and u + v + w + z = 3)
Alternatively, an organic metal containing halogen represented by

The conductive thin film to be grown is not limited to Al, but may be an Al alloy containing Al as a main component, and the gas for growing Al is not limited to DMAH and may be Al ( C ₂ H ₅ ) ₂ H and Al (CH
₃ ) Other organic metals such as ₃ may be used, and further, a conductive thin film having high electromigration resistance such as Cu may be used.

Further, although the semiconductor device using the silicon substrate as the substrate has been described, it is not limited to the semiconductor device using the silicon substrate, and the SOS or SOI type semiconductor device using the sapphire substrate is used. Further, it is also applicable to a dielectric base transistor using a ferroelectric substrate, an optical IC using a ferroelectric substrate, or the like.

[0047]

According to the present invention, the conductive thin film is vapor-deposited after the pretreatment of the substrate using the organometallic gas containing halogen, which is relatively safe. It is possible to grow a conductive thin film having excellent surface morphology by using the phase growth apparatus as it is, which contributes to high integration of semiconductor devices and the like, and also contributes to reduction of manufacturing cost.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a principle configuration of the present invention.

FIG. 2 is an explanatory diagram of a vapor phase growth apparatus used for carrying out the present invention.

FIG. 3 is an explanatory diagram of the first embodiment of the present invention.

FIG. 4 is an explanatory diagram of a second embodiment of the present invention.

[Explanation of symbols]

1 Substrate 2 Base Insulating Film 3 Conductive Region 4 Organic Metal Gas Containing Halogen 5 Source Gas 6 Conductive Thin Film 11 Container 12 DMAH 13 MFC 14 MFC 15 Pressure Gauge 16 Pressure Control Valve 17 Valve 18 Valve 19 MFC 20 Piping 21 Container 22 DEAC 23 MFC 24 MFC 25 Pressure gauge 26 Pressure control valve 27 Valve 28 Valve 29 MFC 30 Chamber 31 Carbon susceptor 32 Semiconductor substrate 33 RF coil 34 Exhaust port 41 Silicon substrate 42 SOG film 43 TiN film 44 DEAC 45 DMAH 46 Al layer 51 Silicon Substrate 52 SOG Film 53 TiN Film 54 Al Layer 55 TiN Film 56 SiO ₂ Film 57 Via Hole 58 DEAC 59 DMAH 60 Al Plug

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location H01L 21/306 H01L 21/302 P

Claims (6)

[Claims] 1. A conductive layer characterized in that an organic metal gas containing halogen is supplied to treat the surface of the conductive region before vapor-depositing a conductive thin film on the conductive region provided on a substrate. Thin film vapor deposition method. 2. In the step of vapor-depositing a conductive thin film on a conductive region provided on a substrate, an organic metal gas containing halogen is supplied together with a raw material gas of the conductive thin film to supply the surface of the conductive region. A method for vapor-phase growth of a conductive thin film, which comprises: 3. The vapor phase of the electroconductive thin film according to claim 1, wherein the organometallic gas containing halogen contains at least one of the metal elements constituting the electroconductive thin film. How to grow. 4. The vapor phase of the conductive thin film according to claim 1, wherein the conductive thin film is made of Al or an Al alloy containing Al as a main component. How to grow. 5. The halogen-containing organometallic gas is R
The C _x H _y, 'the C _x' R H _y 'case of a, AlR _u R'
_v Cl _w F _z (where u, v, w and z are integers, and
It is represented by u + v + w + z = 3), The vapor phase growth method of the electroconductive thin film of any one of Claim 1 thru | or 4 characterized by the above-mentioned. 6. The u, v, w, and _z in the AlR _u R ′ _v Cl _w F z are u = 2, v = 0, w = 1, and z.
= 0 or u = 2, v = 0, w = 0, and z = 1
The vapor phase growth method for a conductive thin film according to claim 5, wherein