JP3261440B2 - Aluminum film formation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, a method of forming an aluminum film on a semiconductor wafer by CVD (Chemical Vap).
or Deposition).

[0002]

2. Description of the Related Art In general, a semiconductor device tends to have a multilayer wiring structure in response to recent demands for higher density and higher integration. In this case, a lower device and an upper aluminum wiring are required. Embedding technology such as a contact hole as a connection portion with the via and a via hole as a connection portion between the lower aluminum wiring and the upper aluminum wiring has become important in order to make an electrical connection between them. It is preferable to use an inexpensive and highly conductive material, for example, aluminum, for filling the contact holes and via holes, and it is highly directional to eliminate the occurrence of voids due to the technical restriction of filling holes. CVD (Chemi) with good step coverage instead of film formation by sputtering
It is desired to form a film by cal vapor deposition. Examples of such a metal thin film forming apparatus include JP-A-6-267951 and JP-A-6-267951.
An apparatus disclosed in, for example, Japanese Patent No. 283446 is known.

In order to form an aluminum-CVD film,
Generally, DMAH which is an organic metal gas is used as a processing gas.
(Dimethyl aluminum hydride) is used, and this DMAH is a substance that is extremely difficult to handle because it reacts violently with moisture and oxygen in the air and ignites.

[0004]

Therefore, at present, a technique for forming a high quality aluminum-CVD film with good mass productivity has not been sufficiently developed at present. In particular, the aluminum film, unlike other metal film formation, very easily combines with moisture and oxygen components in the air to form an oxide film that causes deterioration of characteristics, so that the film formation technology of aluminum-CVD is difficult. Of course, the management of the semiconductor wafer before and after the film formation process must also pay close attention,
Before film formation, moisture and natural oxide film adhering to the wafer surface are efficiently removed, and after film formation, the wafer temperature is efficiently lowered to the handling temperature to suppress the adhesion of the natural oxide film. There must be. In particular, regarding the adhesion of a natural oxide film after the formation of aluminum, in the current situation where the semiconductor device itself has become denser and more minute, even a slight adhesion of the natural oxide film causes deterioration of the characteristics, and this should not be eliminated as much as possible. I have to. The present invention has been devised in view of the above problems and effectively solving them. An object of the present invention is to provide a method for forming an aluminum film capable of obtaining a CVD aluminum film having good electrical characteristics and quality.

[0005]

According to a first aspect of the present invention, in order to solve the above-mentioned problems, when an aluminum film is formed on an object to be processed in a processing vessel by thermal CVD, the aluminum film in the processing vessel is formed. The configuration is such that the base pressure is set to 5 × 10 ⁻⁶ Torr or less. A second aspect of the invention is to solve the above problems, a deposition treatment chamber is formed by a C VD aluminum film with respect to the workpiece, prior to about the formation of the aluminum film to the target object When forming an aluminum film by a cluster tool device in which a plurality of processing chambers for performing processing or post-processing are connected to and blocked from a common transfer chamber so as to be able to communicate with each other, at least the film formation processing chamber, the common transfer chamber, The base pressure in the processing chamber for performing the post-processing is set to 5 × 10 ⁻⁶ Torr or less.

According to the first aspect of the present invention, the base pressure in the processing chamber is set to a high vacuum of 5 × 10 ⁻⁶ Torr or less.
Water molecules and oxygen gas molecules existing in the container can be reduced as much as possible. As a result, it is possible to minimize the attachment of a natural oxide film to the aluminum film or the like immediately before film formation and the attachment of moisture. it can. According to a second aspect of the invention, an aluminum film is formed by a cluster tool device. As a pretreatment before the aluminum film formation, moisture and a natural oxide film on the surface of the object to be processed are removed in a pretreatment processing chamber. An aluminum film is formed by CVD in a film forming chamber in which the base pressure is set to 5 × 10 ⁻⁶ Torr or less.
In this case, since the base pressure in the film forming chamber is set to 5 × 10 ⁻⁶ Torr or less as in the first invention, the natural oxide film adheres to the aluminum film immediately before the film formation, and Can be suppressed as much as possible.

The object on which the aluminum film has been formed in this way is transferred to a post-processing chamber through a common transfer chamber, where the object to be processed is cooled to a handling temperature, for example. Since the base pressure is set to 5 × 10 ⁻⁶ Torr or less also in the post-treatment processing chamber and the common transfer chamber, the aluminum film is formed in the transfer process and the post-process of the object after film formation. It is possible to minimize the attachment of the natural oxide film.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the method for forming an aluminum film according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a schematic plan view showing a cluster tool device used when performing a method of forming an aluminum film according to the present invention, and FIG. 2 is a configuration diagram showing a moisture removal processing chamber for performing a moisture removal process as a pretreatment. 3 is a configuration diagram showing an oxide film removal treatment chamber for performing a natural oxide film removal treatment on the surface of the object as a pretreatment, and FIG. 4 is a pretreatment for removing harmful gas components adhering to the surface of the object. FIG. 5 is a configuration diagram showing a gas component removal processing chamber for performing processing, FIG. 5 is a configuration diagram showing a film formation processing chamber, and FIG. FIG. In the present invention, a case where a semiconductor wafer is used as an object to be processed and an aluminum film is formed on this surface by a thermal CVD process will be described as an example.

First, a cluster tool device for carrying out the method of the present invention will be described. As shown in FIG. 1, the cluster tool device 2 has a common transfer chamber 4 formed in an octagonal container shape from, for example, aluminum at its center, and the first and second cassette chambers 6 around the common transfer chamber 4. 8. A water removal processing chamber 10 for removing water from the wafer surface as a pretreatment, a gas component removal processing chamber 12 for removing a gas component on the wafer surface as a pretreatment, and a natural oxide film on the wafer surface as a pretreatment. Oxide film removal processing chamber 14,
The first and second film forming processing chambers 16 and 18 and a cooling processing chamber 20 for cooling a wafer as post-processing are connected via gate valves G1 to G8 which can be opened and closed, respectively.

The water removal processing chamber 10 is a processing chamber for heating a semiconductor wafer to remove moisture and the like adhering to the surface thereof as a pretreatment for film formation. This is a processing chamber in which a natural oxide film formed on the wafer surface after the above-mentioned water removal is removed by etching, and an H ₂ gas (in the case of a blanket) is used as an etching gas depending on the type of aluminum film formed in a later step.
Or BCl ₃ gas (in the case of selective). The gas component removal processing chamber 12 is a processing chamber that completely separates and removes the gas components remaining on the wafer surface as a pretreatment by heating or ultraviolet irradiation when a harmful gas is used in the etching. The chambers 16 and 18 are processing chambers for actually performing aluminum CVD film formation on the wafer surface, and the cooling processing chamber 20 is a processing chamber for cooling a wafer after film formation to a handling temperature as post-processing.

The first and second cassette chambers 6 and 8 have:
For example, gate doors GD1 and GD2 for loading and unloading a cassette C capable of accommodating 25 wafers W are provided so as to be openable and closable, and a cassette table (not shown) is moved up and down in each of the cassette chambers 6 and 8. It is provided as possible. The cassette chambers 6 and 8 can be supplied with an inert gas, for example, N ₂ gas, and can be evacuated, so that the inside can be evacuated to a high vacuum of, for example, about 5 × 10 ⁻⁶ Torr or less. Has become.

In the common transfer chamber 4, a rotation positioning mechanism 22 for positioning the wafer W loaded therein, and a transfer arm 24 composed of a multi-joint arm mechanism capable of bending, stretching and rotating while holding the wafer W. The wafers can be loaded and unloaded between the chambers by bending, stretching and rotating. In the common transfer chamber 4, a gas supply system 19 for supplying an inert gas, for example, N ₂ gas, a turbo molecular pump 21, for example,
A vacuum evacuation system 25 with a dry pump 23 interposed is connected, and the inside can be evacuated to, for example, a high vacuum. The water removal treatment apparatus 10 shown in FIG.
For example, a processing container 26 having a bottomed cylindrical shape made of aluminum is provided. The ceiling is opened, and a ceiling plate 28 can be air-tightly detached with screws 30 here. For example, an O-ring 32 for ensuring the sealing performance is interposed in the mounting portion of the ceiling plate 28.

A mounting table mounting step 34 is provided on a lower side wall in the processing container 26, and a unit mounting plate 38 made of, for example, stainless steel is detachably fixed thereto by screws 42. On the mounting plate 38, for example, a mounting table 4 made of graphite whose surface is coated with SiC.
0 is provided, and the wafer W is placed on this upper surface. For example, a carbon heater 4 entirely coated with SiC is provided on substantially the entire upper surface of the mounting table 40.
4, the wafer W can be heated to a predetermined temperature, for example, about 300 ° C.

Further, lifter pins 46 are provided which penetrate the unit mounting plate 38 and the mounting table 40 in the up and down direction and are capable of moving up and down in the up and down direction. It can be moved up and down. A terminal unit mounting hole 47 having a stepped opening is formed in the bottom 26A of the processing container 26, and a sealing member 49 is interposed therebetween so that the mounting hole 47 is airtightly closed. A terminal unit 48 is detachably attached by screws 50 from below the container bottom 26A. The terminal unit 48 includes two insulated extraction terminals 5 penetrating into and out of the container.
2 and 52 are provided, and these terminals 52 and 52 are connected to heater terminals 54 and 54 provided below the unit mounting plate 38 and electrically connected to the heater 44 by wires 56.

The lower ends of the lead-out terminals 52, 52 are connected to a heater power supply 60 via wirings 58, 58 detachably mounted by screws 62. It is supposed to. The terminal unit 48 and the unit mounting plate 38
Are integrally connected by connecting connecting rods 64 and 66 extending from opposite sides with screws 68. Therefore, by removing the screw 42 fixing the unit mounting plate 38 to the container side and the screw 50 fixing the terminal unit 48 to the bottom 26A side, the mounting table 40 including the heater 44 is removed.
And the terminal unit 48 can be integrally removed from the container 26. Further, a cooling jacket 70 for flowing, for example, cooling water and cooling the same is provided in the mounting table mounting step 34 of the container 26. A gas introduction nozzle 72 for introducing an inert gas, for example, N ₂ gas, into the container and an exhaust port 73 for exhausting the atmosphere in the container are provided on the side wall of the container 26.
The exhaust port 73 is provided with an on-off valve 80,
An exhaust system 78 provided with a turbo molecular pump 74, a dry pump 76, and the like is connected so that the inside of the processing container 26 can be evacuated to a high vacuum of, for example, 5 × 10 ⁻⁶ Torr or less. A wafer transfer port 82 is provided on the other side wall, and communicates with the common transfer chamber 4 here.
The gate valve G3 for shutting off is provided.

Next, referring to FIG.
4 will be described. As shown in FIG. 3, the oxide film removal processing chamber 14 is configured as an RIE (Reactive Ion Etching) plasma apparatus, and has a processing container 84 formed into a bottomed cylindrical body by, for example, aluminum. Inside, a mounting table 88 made of a conductive material such as aluminum, which is supported on the container bottom 84A via an insulating material 86, is provided, and constitutes a lower electrode. A high-frequency power source 1 for generating plasma of 13.56 MHz, for example, is connected to the mounting table 88 via a power supply line 102 on the way of an open / close switch 98 and a matching box 100.
04. On the upper surface of the mounting table 88, for example, an electrostatic chuck 90 made of polyimide having a conductive foil embedded therein is provided.
2 and a high-voltage DC power supply 96 via an open / close switch 94, and when necessary, attracts and holds the wafer W on the electrostatic chuck surface by Coulomb force. Further, a focus ring 106 is provided on the periphery of the upper surface of the mounting table 88 so as to surround the periphery of the wafer W on the same plane, so that uniformity of plasma processing in the wafer surface is ensured. ing.

The mounting table 88 and the electrostatic chuck 9
The lifter pins 108 are provided so as to be able to penetrate vertically and penetrate in the vertical direction, and lift and lower the wafers W when loading and unloading the wafers W. An extendable bellows 110 is provided on the lower surface of the mounting table 88 in a gas-tight manner through a bellows hole 112 provided in the container bottom 84A.
10, so that the lifter pin 108 can be moved up and down while maintaining the airtightness in the processing container 84. In addition, a ceiling plate 116 is provided airtightly on a ceiling portion of the processing container 84 via a sealing member 114.
The ceiling plate 116 is provided with a shower head 120 having a diffusion plate 118 therein to constitute an upper electrode. On the lower surface of the shower head 120, a gas ejection surface 124 having a large number of ejection holes 122 is provided. On the side wall of the shower head 120, a cooling jacket 126 for cooling the head portion by flowing, for example, cooling water is provided.

An H ₂ gas supply system 130 used when H ₂ gas is used as an etching gas and a BCl ₃ gas supply system used when BCl ₃ gas is used as an etching gas are provided at a gas inlet 128 above the shower head 120. 32 are connected, and each system is connected to the H through a mass flow controller 134 and an on-off valve 136 on the way.
₂ gas source 138 and BCl ₃ gas source 140 are connected. Here, using H ₂ gas as the etching gas in forming a blanket aluminum layer in a later step, when forming the selective aluminum film, using BCl ₃ gas. In addition, as the carrier gas, for example, an Ar gas source 15
Ar gas from No. 4 is used, and although not shown, N ₂ for purging can also be supplied. In addition, the processing container 8
An exhaust port 142 is provided in the peripheral portion of the bottom portion 84A of the fuel cell 4, and a turbo molecular pump 146 and a dry pump 148 are provided in the exhaust port 142 in the same way as in the water removal treatment chamber 10 shown in FIG. Vacuum evacuation system 150 is provided,
The inside of the container can be evacuated to a high degree of vacuum of, for example, 5 × 10 ⁻⁶ Torr or less. Further, the processing container 84
The gate valve G5 for communicating with and shutting off the common transfer chamber 4 is provided in the side wall of the wafer.

Next, the gas component removal processing chamber 12 will be described with reference to FIG. This gas component removal processing chamber 12
Is the harmful gas adhering to the wafer surface as described above,
For example, it separates and removes BCl ₃ , and has exactly the same configuration as the previous water removal treatment chamber 10 shown in FIG. 2 except that an ultraviolet irradiation unit is provided. In the following, the same portions are denoted by the same reference numerals, and the description thereof will be omitted. The ultraviolet irradiation means 156 will be described.

That is, the ceiling portion 28 of the processing container of the gas component removal processing chamber 12 has a large-diameter ultraviolet transmitting hole 158.
The transmission hole 158 has a transparent plate 16 made of a material transparent to ultraviolet rays, for example, quartz.
0 is provided in an airtight manner via a seal member 166. A lamp housing box 162 is attached to and fixed to the upper surface of the ceiling by a screw 164 via a pressing member 168 so as to cover the entire upper part of the transmission plate 160. An ultraviolet lamp 170 is housed in the lamp housing box 162, and the semiconductor wafer W provided on the mounting table 40 is moved to the lamp 170.
At the same time, the wafer is heated to a predetermined temperature, for example, about 300 ° C. by a heater 44 provided on the mounting table 40 so as to excite Cl ions or the like adhering to the wafer surface, thereby irradiating the wafer surface with ultraviolet rays UV. It can be separated from. In this case, the N ₂ gas and the H ₂ gas can be supplied from the gas introduction nozzle 72 into the processing container 26 as needed. In addition, an on-off valve 80,
A vacuum evacuation system 78 provided with a turbo molecular pump 74, a dry pump 76, and the like is connected so that the inside of the processing container 26 can be evacuated to a high vacuum of, for example, 5 × 10 ⁻⁶ Torr or less. The common transfer chamber 4 is connected to the wafer transfer port 82 provided on the side wall of the processing container 26 via the gate valve G4.

Next, based on FIG.
8 will be described. Since both the film formation processing chambers 16 and 18 are configured in exactly the same way, the first film formation processing chamber 16 will be described as a representative here as an example, and the structure of the second film formation processing chamber 18 will be described. Omitted. The film formation processing chamber 16 has a heat C
It is configured as a VD film forming apparatus, and has a processing container 172 formed into a cylindrical shape by, for example, aluminum.
A feed line insertion hole 174 is formed at the center of the bottom 172A of the processing container 172, and a peripheral portion is provided with a vacuum pumping system such as a turbo molecular pump 176 and a vacuum pumping system 179 provided with a dry pump 178. A connected exhaust port 180 is provided, and the inside of the container is, for example, 5 ×
It can be evacuated to a high vacuum of 10 ^-6 Torr or less.

A disk-shaped mounting table 182 made of, for example, alumina is provided in the processing container 172.
A cylindrical leg portion 184 extending downward is provided at the center of the lower surface of the base 82.
The lower end of the leg portion 184 is hermetically attached and fixed to the periphery of the feeder line insertion hole 174 of the container bottom portion 172A using a bolt 188 or the like with a sealing member 186 such as an O-ring interposed therebetween. You.

A resistance heating element 190 made of, for example, carbon coated with SiC is embedded in the entire upper surface of the mounting table 182, and a semiconductor wafer W as an object to be processed mounted on the upper surface side is mounted thereon. It can be heated to a desired temperature. On the upper surface of the mounting table 182, there is provided a thin ceramic electrostatic chuck 192 in which a conductive plate (not shown) such as copper is embedded, and the Coulomb force generated by the electrostatic chuck 192 causes The upper surface holds the wafer W by suction. still,
Instead of the electrostatic chuck 192, a mechanical clamp may be used to hold the wafer W, or it may not be provided. An insulated lead wire 194 is connected to the resistance heating element 190.
Is drawn out through the inside of the cylindrical leg 184 and through the feeder line insertion hole 174, and is connected to the feeder 198 via the open / close switch 196. Further, an insulated lead wire 200 is connected to a conductive plate (not shown) of the electrostatic chuck 192, and this lead wire 200 is also drawn out through the inside of the cylindrical leg portion 184 and the feeder line insertion hole 174, It is connected to a high-voltage DC power supply 204 via an open / close switch 202.

A plurality of lifter holes 206 are provided at predetermined positions in the periphery of the mounting table 182 and the electrostatic chuck 192 so as to penetrate in the vertical direction. The wafer lifter pins 208 are accommodated therein, and the lifter pins 208 are moved up and down by a lifting mechanism (not shown) when loading / unloading the wafer W.
The wafer W is lifted or lowered. Generally, three such wafer lifter pins 208 are provided corresponding to the peripheral portion of the wafer.

A ceiling plate 212 integrally provided with a shower head 210 is hermetically attached to the ceiling of the processing vessel 172 via a sealing member 214 such as an O-ring. Mounting table 182
Are provided so as to face each other so as to cover substantially the entire upper surface of the. The shower head 210 is for introducing a processing gas into the processing container 172 in a shower shape.
A number of injection holes 216A for ejecting the processing gas are formed on the injection surface 216 on the lower surface of the nozzle 10.

The shower head 210 is mounted on the ceiling plate 212.
Is provided with a gas introduction port 218 for introducing a processing gas, and a supply passage 220 for flowing the processing gas is connected to the introduction port 218. In the shower head 210, a first diffusion plate 224 having a large number of diffusion holes 222 is provided for the purpose of diffusing the processing gas supplied from the supply passage 220. A plate 226 is provided for each.

A cooling jacket 228 through which, for example, a coolant flows to cool the wall surface is provided on the side wall of the processing container 172.
Is provided, and hot water of, for example, about 50 ° C. is made to flow as a coolant. Also, this container 172
A part of the side wall of the wafer is provided with a wafer loading / unloading port 230,
Here, the gate valve G6 for communicating with and shutting off the common transfer chamber 4 is provided.

On the other hand, the processing gas used for aluminum CVD is obtained by evaporating DMAH, but low-viscosity DMAH is contained in the tank 232 as a raw material liquid, and is supplied to the supply passage 22.
0 is immersed in the raw material liquid 234. Further, on the liquid surface in the tank 232, an end of a pressure-feeding pipe 238 connected to an Ar cylinder 236 filled with Ar gas at a pressure of, for example, about 3 kgf / cm 2 is positioned, and the viscosity of the gas is increased by the Ar gas pressure. It is designed to pump a low raw material liquid.

In the middle of the supply passage 220, a liquid mass flow controller 240 and a vaporizer 242 using H ₂ gas as a vaporizing gas and a carrier gas are sequentially provided, and the liquid DMAH is vaporized therein to process the processing vessel 172. It is designed to be supplied inside. In the supply passage 220 downstream of the vaporizer 242, for example, a tape heater 244 (shown by a broken line in the drawing) for preventing reliquefaction is provided, and this is heated to a predetermined temperature, for example, about 60 ° C. ing. Alternatively, the stock solution of DMAH may be heated to, for example, about 80 ° C., the viscosity may be reduced in the same manner as described above, and the DMAH may be pumped in this state.

Next, the cooling processing chamber 20 for performing post-processing will be described with reference to FIG. This cooling processing chamber 20
This processing chamber performs a post-process of cooling the wafer W heated by the film forming process in the film forming process chamber 16 or 18 to the handling temperature. This cooling processing chamber 20
Has a processing container 246 molded into a cylindrical shape with a bottom, for example, made of aluminum. A cooling table 248 made of, for example, aluminum is provided inside the processing container 246, and the wafer W is placed on the upper surface thereof. I am getting it. The cooling stand 248 is provided with a cooling jacket 250 for flowing a cooling medium, for example, cooling water at 25 ° C., for example, to cool the cooling water.
It is designed to cool to about ° C. Further, the cooling table 248 is provided with lifter pins 252 which can be moved up and down through the cooling table 248. When the wafer W is loaded and unloaded, the lifter pin 252 is raised and lowered to lift or lower the wafer W. Or

In the processing container 246, the ceiling plate 25
4 is hermetically attached via a seal member 256 so as to be detachable, and an exhaust port 258 is provided in the periphery of the container bottom 246A. The exhaust port 258 has a vacuum provided with a turbo molecular pump 260 and a dry pump 262. Exhaust system 2
64 is connected so that the inside of the container can be evacuated to a high degree of vacuum of, for example, 5 × 10 ⁻⁶ Torr or less. A gas nozzle 266 for supplying an inert gas, for example, an Ar gas, is formed on one side wall of the processing container 246, and a wafer loading / unloading port 268 is provided on the other side wall. The above-mentioned gate valve G8 for communicating and shutting off is provided.

Next, the method of the present invention performed using the cluster tool device configured as described above will be described. First, the overall flow of the semiconductor wafer W will be described with reference to FIG. First, since the aluminum film easily reacts with air or moisture to form an oxide film, the cassette chamber 6 is formed.
8, each processing chamber 10, 12, 14, 1 including the common transfer chamber 4.
When not used, 6, 18 and 20 are maintained at a high vacuum of, for example, 5 × 10 ⁻⁶ Torr or less as a base pressure to prevent the formation of a natural oxide film. Such a high degree of vacuum can be achieved by driving a turbo molecular pump and a dry pump connected to the respective exhaust systems.

When an unprocessed semiconductor wafer W is loaded from the outside into the first cassette chamber 6 through the gate door 1 with the unprocessed semiconductor wafer W accommodated in the cassette C, it is sealed and the first
The inside of the cassette chamber 6 is evacuated to the above-mentioned base pressure or lower. When the base pressure of 5 × 10 ^-6 Torr is reached,
The gate valve G1 is opened, the transfer arm 24 in the common transfer chamber 4 maintained at a base pressure of 5 × 10 ⁻⁶ Torr in advance is extended, and one unprocessed wafer W is taken out. To detect and align the orientation flat of the wafer. The wafer W after the alignment is preliminarily 5 × 10 ⁻⁶ Torr through the gate valve G3 that has been opened using the transfer arm 24.
The wafer W is conveyed into the moisture removal processing chamber 10 at a base pressure of r, where the wafer W is heated to vaporize and remove moisture adhering to the wafer surface.

Next, the wafer W from which water has been removed is carried into the oxide film removal processing chamber 14 which is maintained at a base pressure of 5 × 10 ⁻⁶ Torr in advance through the gate valve G5, and is etched therein. Removes the natural oxide film adhering to the wafer surface. Here, when a selective aluminum film is formed in a subsequent step, for example, a BCl ₃ gas is used as an etching gas, and when a blanket aluminum film is formed, for example, an H ₂ gas is used as an etching gas. When BCl ₃ gas is used as an etching gas, Cl ions and B ions, particularly Cl ions, have an adverse effect on the electrical characteristics of the aluminum film, so that these ions must be completely removed from the wafer surface. Then, the wafer W after the etching using the BCl ₃ gas is carried into the gas component removal processing chamber 12 which has been preliminarily set to the base pressure of 5 t: 10 ⁻⁶ Torr through the gate valve G4. Excites Cl ions by heating and irradiation with ultraviolet rays, and separates them from the wafer surface to eliminate them. The preprocessing for the wafer is completed as described above.

The wafer W from which the gas components have been removed in this manner is then placed in the first or second film forming chamber 16 or 18 which has been previously set to a base pressure of 5 × 10 ⁻⁶ Torr by a gate valve. Introduced via G6 or G7. The reason for providing the two film-forming processing chambers 16 and 18 as described above is as follows.
This is to improve the throughput in view of the time required for the film forming process. When H ₂ gas is used as the etching gas instead of BCl ₃ gas in the oxidation removal processing chamber 14, the wafer is directly passed through the first or second wafer without passing through the gas component removal processing chamber 12. It will be carried into the film formation processing chamber. For the wafer carried into the film formation processing chamber 16 or 18, for example, a gas obtained by vaporizing DMAH (dimethyl aluminum hydride) is used as a processing gas, and an aluminum film is formed at a predetermined temperature by CVD processing here. Will be.

Next, the wafer W after the formation of the aluminum film is preliminarily supplied to the gate valve G8 at 5 × 10 ^-6 Torr.
, And is cooled to a predetermined handling temperature as a post-process. Then, the processed wafer W is then transferred to the cassette C in the second cassette chamber 8 maintained at a base pressure of 5 × 10 ⁻⁶ Torr in advance via the gate valve G2.
Will be accommodated. In this way, unprocessed wafers are sequentially flown and processed, and during a film forming process requiring a relatively long processing time, the throughput is improved by using the vacant film forming processing chamber.

Next, specific processing in each processing chamber will be described individually. First, the water removal process will be described with reference to FIG. In FIG. 2, the wafer W mounted on the mounting table 40 is heated by energizing a heater 44 embedded in the mounting table 40 from a heater power supply 60. The heating temperature of the wafer W at this time is, for example, 400 ° C.
The internal atmosphere is an inert N ₂ gas atmosphere, and the pressure is set to, for example, about 5 × 10 ⁻⁶ Torr. The water on the wafer surface is vaporized by the heating, and the vaporized water is removed by suction by the exhaust system 78. The processing time depends on, for example, the processing temperature, but is set to about 180 seconds when the processing temperature is about 400 ° C. Before processing
As described above, the inside of the processing container 26 is
The base pressure is maintained at × 10 ⁻⁶ Torr to prevent a natural oxide film from adhering to the surface of the loaded wafer. During the processing period, a coolant is caused to flow through the cooling jacket 90 provided in the processing container 26 to prevent the temperature of the processing container 26 from excessively rising, thereby maintaining safety.

Next, the oxide film removing process will be described with reference to FIG. 3, the wafer W placed on the mounting table 88 is suction-held on the mounting surface by Coulomb force generated from the electrostatic chuck 90, and in this state, the lower part is supplied while supplying the etching gas from the shower head 120. 13.56 M from the high frequency power supply 104 to the mounting table 88 as an electrode
A high frequency voltage of Hz is applied, plasma is generated between the high frequency voltage and the shower head 120 as the upper electrode, and a plasma etching process is performed. Here, as described above, a BCl ₃ gas is used as an etching gas when forming a selective aluminum film in a post-process, and an H ₂ gas is used as an etching gas when forming a blanket aluminum film.

At this time, the etching conditions are BCl ₃ , A
When flowing r gas, BCl ₃ gas is supplied at 400 SCCM.
About 100 SCCM of Ar gas and about 100 SCCM of H ₂ gas when flowing, and the process pressure is set to about 40 m to 150 mTorr, the wafer temperature is set to 60 ° C. or less, and the etching process is performed for about 60 to 240 seconds. . In this case, a coolant is caused to flow through the cooling jacket 126 to cool the shower head 120 so that the shower head 120 is not excessively heated. Also, here, before the processing, the inside of the processing container 84 is maintained at the base pressure of 5 × 10 ⁻⁶ Torr by the vacuum exhaust system 150 as described above.
The natural oxide film is prevented from adhering to the surface of the loaded wafer.

Next, the gas component removing process will be described with reference to FIG. In FIG. 4, the wafer W placed on the mounting table 40 is heated by the heater 44 to a predetermined temperature, for example, about 300 ° C., and at the same time, for example, the wavelength is emitted from the ultraviolet lamp 170 of the ultraviolet irradiation means 156 located thereabove. The UV light of 254 nm is emitted, and this UV light passes through the transmission plate 160 and irradiates the wafer surface. With the synergistic effect of heating by the heater 44 and irradiation of ultraviolet rays,
BCl ₃ molecules, B ions, C attached to the wafer surface
Gas components such as L ions are excited to a higher energy order,
This is equal to or more than the bonding energy with the wafer surface, is separated from the wafer surface, is sucked from the exhaust system 78 and is eliminated.

At this time, the inside of the processing container 26 is set to an H ₂ gas or N ₂ gas atmosphere, and the process pressure is 5 m to 15 m.
It is maintained at about 0 mTorr. Although the process time depends on the process temperature and the intensity of ultraviolet UV, when the wavelength is 254 nm and the light intensity is 30 mW / cm ² as described above, the process is performed for about 180 seconds. Also, before the processing, the inside of the processing chamber 26 is maintained at a base pressure of 5 × 10 ⁻⁶ Torr by the vacuum exhaust system 78 as described above, and a natural oxide film adheres to the surface of the loaded wafer. Is preventing that.

Next, a process for forming an aluminum film will be described with reference to FIG. In FIG. 5, the wafer W mounted on the mounting table 182 is suction-held by Coulomb force from the electrostatic chuck 192. In this state, the wafer W is heated to a predetermined process temperature, for example, 200 ° C. by the resistance heating element 190, and at the same time, DMAH is used as a processing gas.
Vaporized gas from the shower head 210 to the processing vessel 172.
, And a CVD film of aluminum is formed on the wafer surface. At this time, the process pressure is maintained at, for example, about 2 Torr, and the DMAH is, for example, 100 SCC in gaseous terms.
Supply about M.

When supplying the processing gas, a low-viscosity raw material liquid 234 is pressure-fed from a tank 232 and is supplied to a vaporizer 2.
At 42, the vaporized gas is vaporized by the H ₂ gas which is both a vaporized gas and a carrier gas, and the generated vaporized gas is introduced into the processing vessel 172 as described above. During the film formation, a coolant of, for example, about 50 ° C. is caused to flow through the cooling jacket 228 provided on the side wall of the processing container 172, and the coolant is cooled to a safe temperature. Here, before the processing, the inside of the processing container 172 is 5 × 10 ⁻⁶ Torr by the evacuation system 179 as described above.
Is maintained at the base pressure of the substrate, thereby preventing the natural oxide film from adhering to the surface of the loaded wafer. After the film formation, the vacuum is again applied to a base pressure of 5 × 10 ⁻⁶ Torr. Therefore, it is possible to minimize the attachment of the natural oxide film to the aluminum film immediately after the film formation.

Next, a wafer cooling process which is a post-process will be described with reference to FIG. In FIG. 6, the cooling stand 248
The wafer W placed immediately above the film forming process has a temperature of about 200 ° C., and is passed through a cooling jacket 250 provided on a cooling stand 248 to a temperature of, for example, about 25 ° C., so that the temperature of the wafer W is about 50 ° C. The wafer W is cooled until the temperature reaches the handling temperature. In this case, the inside of the processing container 246 is set to a pressure, for example, an inert gas atmosphere of, for example, about 1 Torr, for example, an Ar gas atmosphere to suppress generation of an oxide film. Here, before the processing, the inside of the processing chamber 246 is maintained at a base pressure of 5 × 10 ⁻⁶ Torr by the vacuum exhaust system 264 as described above, and the natural oxide film adheres to the aluminum film of the loaded wafer. Is suppressed as much as possible.

When a predetermined process is completed in each of the processing chambers, the inside of the processing container is replaced with the inert gas of 5 ×.
It is evacuated to a base pressure of 10 ^-6 Torr, and is transferred to the next processing chamber via the common transfer chamber 4 or to the second cassette chamber 8 when all processing is completed. As described above, the inside of the common transfer chamber 4 is always 5 × 10 ⁻⁶ Torr by the evacuation system 25 (see FIG. 1).
, The natural oxide film hardly adheres to the wafer surface during the transfer. When forming an aluminum film on the wafer surface in this way,
Since the surrounding atmosphere of the wafer is constantly maintained in a high vacuum state of 5 × 10 ⁻⁶ Torr except during the processing from the pre-processing to the post-processing, a natural oxide film which causes the characteristic deterioration on the wafer surface is obtained. Can be prevented from adhering, and in particular, after the aluminum film is formed, the natural oxide film can be suppressed from adhering to this aluminum film as much as possible. Therefore, it becomes possible to obtain a CVD aluminum film having good electric characteristics.

In the above embodiment, the base pressure is set to 5 × 10
^The case where the pressure is set to ^-6 Torr has been described as an example, but any pressure value below this pressure may be set as the base pressure. FIG. 7 is a graph showing the relationship between the base pressure of the chamber and the resistance value of the via.
It is found that the via resistance value is extremely low by setting the value to ^-6 Torr or less. In particular, considering the time required for evacuation to reach the base pressure and the effect of suppressing the formation of a natural oxide film, the base pressure is set to approximately 1 × 10 ⁻⁶ To.
It is preferable to set to about rr.

In the above embodiment, the film forming chamber in the cluster tool apparatus has been described as an example. However, the method of the present invention can be applied to a case where the film forming chamber is used alone instead of the cluster tool apparatus. Of course you can. Further, the present invention is not limited to the case where the film is formed on a semiconductor wafer, and is of course applicable to the case where the film is formed on another object to be processed, for example, an LCD substrate or a glass substrate.

As described above, according to the method for forming an aluminum film of the present invention, the following excellent functions and effects can be obtained. When forming an aluminum film by CVD, the base pressure in the processing vessel is set to 5 × 10 ^−6.
Since the pressure is set to be equal to or less than Torr, a natural oxide film adhering to the aluminum film of the object to be processed can be largely suppressed, and therefore, a CVD aluminum film having good electric characteristics and quality can be obtained. Also, a plurality of processing chambers for performing pre-processing and post-processing when forming an aluminum film are combined into a cluster tool device, and at least a film forming processing chamber, a common transfer chamber, and a processing chamber for post-processing are formed. Since the base pressure is set to 5 × 10 ⁻⁶ Torr or less, a natural oxide film adhering to the aluminum film of the object to be processed can be further reduced.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing a cluster tool device used when performing a method for forming an aluminum film according to the present invention.

FIG. 2 is a configuration diagram illustrating a moisture removal processing chamber for performing a moisture removal process as a pretreatment.

FIG. 3 is a configuration diagram showing an oxide film removal processing chamber for performing a natural oxide film removal process on the surface of a processing object as a pretreatment.

FIG. 4 is a configuration diagram showing a gas component removal processing chamber for performing a removal process of a harmful gas component adhering to the surface of an object to be processed as a pretreatment.

FIG. 5 is a configuration diagram illustrating a film formation processing chamber.

FIG. 6 is a configuration diagram illustrating a cooling processing chamber for performing cooling processing on a target object after film formation as a post-processing.

FIG. 7 is a graph showing a relationship between a base pressure of a chamber and a resistance value of a via.

[Explanation of symbols]

 2 Cluster tool device 4 Common transfer room 6 First cassette room 8 Second cassette room 10 Moisture removal treatment room (pretreatment room) 12 Gas component removal treatment room (pretreatment room) 14 Oxide film removal treatment room (pretreatment room) 16 First film formation processing chamber 18 Second film formation processing chamber 20 Cooling processing chamber (post-processing chamber) 24 Transfer arm 44 Heater 48 Terminal unit 156 Ultraviolet irradiation means 170 Ultraviolet lamp 172 Processing container 179 Vacuum exhaust system 270 Airtight Box 272 Clean gas introduction port 274 Gas exhaust port W Semiconductor wafer (workpiece)

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shigetoshi Hosaka 2381 Kita Shimojo, Fujii-machi, Nirasaki-shi, Yamanashi Prefecture Inside Tokyo Electron Yamanashi Co., Ltd. (72) Inventor Toru Ikeda 6-5 Hiyoshidai, Tomisato-cho, Inba-gun, Chiba Prefecture -11 (56) References JP-A-6-41747 (JP, A) JP-A-61-166970 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C23C 16/00- 16/56 H01L 21/205 H01L 21/285

Claims (2)

(57) [Claims] 1. An aluminum film is applied to an object to be processed by CV.
A cluster tool in which a film forming processing chamber for forming a film by D and a plurality of processing chambers for performing pre-processing or post-processing related to film formation of an aluminum film on the object to be processed can be connected to and blocked from a common transfer chamber. When an aluminum film is formed by the apparatus, the base pressures of at least the film forming processing chamber, the common transfer chamber, and the processing chamber for performing the post-processing are set to 5 × 10 ⁻⁶ Torr or less, respectively. A method for forming an aluminum film. The processing chamber wherein performing the post-processing method of forming an aluminum film of claim 1, wherein the cooling the object to be processed after the aluminum deposition.