JP4335981B2 - High temperature reflow sputtering method and high temperature reflow sputtering apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a high-temperature reflow sputtering technique in which a metal material is embedded in a hole formed in a substrate.
[0002]
[Prior art]
In the manufacture of a semiconductor device typified by LSI (Large Scale Integrated Circuit), a step of embedding a metal material in a minute hole is required. For example, a plug embedding process for embedding a wiring material in a contact hole provided in the electrode part to establish conduction with the underlying channel, or a process for embedding an interconnect material in an interlayer through hole in a multilayer wiring structure to perform interlayer wiring is performed. It has been broken.
Such embedding is performed by depositing a thin film in the hole. This embedding has been developed so far by the combined use of metal CVD (chemical vapor deposition) and high temperature reflow sputtering. In metal CVD, for exampleWF ₆ Typically, a tungsten film is formed by a reduction reaction (blanket tungsten). In high-temperature reflow sputtering, a target made of an aluminum alloy is typically sputtered.
[0003]
However, high-density reflow sputtering has been considered to be more advantageous than metal CVD, which increases process costs, as the density of devices and multilayer wiring increases. High-temperature reflow sputtering has an advantage that the wiring resistance can be suppressed smaller than that of metal CVD even when the diameter or width of the hole opening (hereinafter referred to as the hole width) is reduced, and is 0.25 μm to 0.18 μm. Promising for filling the hole width.
[0004]
Further, the degree of integration of the device is further increased, and in a device having a hole width of about 0.13 μm (4-megabit DRAM (Dynamic Random Access Memory) class), the plug resistance value becomes the limit when embedded with an aluminum alloy. It has also been pointed out that there is a possibility to change from an aluminum alloy to a copper alloy. Therefore, in the future, high-temperature reflow sputtering for sputtering a target made of a copper alloy must also be taken into consideration.
[0005]
FIG. 5 is a front view showing a schematic configuration of a conventional high-temperature reflow sputtering apparatus that performs such high-temperature reflow sputtering.
The sputtering apparatus shown in FIG. 5 includes a sputter chamber 2 provided with an exhaust system 21 and a sputter sputtering chamber 2.Sputtered surface 220, A target 22 provided so as to be exposed, a sputtering power source 23 for sputtering the target 22, and emitted by sputteringTarget 22A substrate holder 24 for placing the substrate 9 at a predetermined position in the sputtering chamber 2 where the material reaches, a process gas introduction system 25 for introducing a predetermined process gas into the sputtering chamber 2, and the substrate 9 at a predetermined temperature. A heater 26 provided in the substrate holder 24 is provided for heating.
[0006]
The target 22 is made of, for example, an aluminum alloy, and is attached to the sputter chamber 2 via an insulating material 221. The sputtering power source 23 is configured to apply a negative high voltage to the target 22. When a process gas such as argon is introduced into the sputter chamber 2 by the process gas introduction system 25 and a negative high voltage is applied to the target 22, it is between the substrate holder 24 that is at ground potential and the wall of the sputter chamber 2. A DC electric field is set, and sputter discharge is generated by this DC electric field. Metal material particles (usually in an atomic state, hereinafter referred to as sputtered particles) released from the target 22 by this sputtering discharge reach the substrate 9 and deposit an aluminum alloy thin film.
[0007]
On the other hand, heat from the heater 26 is given to the substrate 9 via the substrate holder 24. AndThe heater 26 is a control unit.The substrate 9 is controlled to a predetermined temperature. The thin film deposited or being deposited on the surface of the substrate 9 is fluidized (reflowed) by the heat of the substrate 9 and flows into fine holes. As a result, the aluminum alloy is buried in the hole, and the surface of the substrate 9 is flattened.
[0008]
[Problems to be solved by the invention]
Currently, there is a demand for processing the substrate so as not to exceed 450 ° C. against the background of higher density devices, more complex multilayer wiring, higher speed, higher functionality, and the like. However, in the above-described high-temperature reflow sputtering, whether it is an aluminum alloy or a copper alloy, unless the substrate is heated to a high temperature of 500 ° C. or higher, it does not fluidize sufficiently and it is difficult to sufficiently fill the hole. When reflowing is performed at a temperature exceeding 450 ° C., for example, there is a problem that a TiN film or the like formed as a barrier for the underlayer is destroyed. Further, when interlayer wiring is performed by reflowing at a temperature exceeding 450 ° C., there is a problem that thermal damage such as reflow of the wiring material of the underlying layer occurs.
[0009]
The invention of the present application has been made to solve such a problem, and a high-temperature reflow sputtering method capable of embedding a wiring material in the inner surface of a fine hole while keeping the temperature of the substrate relatively low. The purpose is to provide.
[0010]
[Means for Solving the Problems]
  In order to solve the above problems, the invention according to claim 1 of the present application is a high-temperature reflow sputtering method in which aluminum or an aluminum alloy is embedded in a fine hole formed in a substrate,
A first step of thinly forming a base thin film of aluminum or aluminum alloy on the side surface and bottom surface of the hole, and after the first step, a thin film of aluminum or aluminum alloy is further deposited and reflowed into the hole. A second step of embedding aluminum or aluminum alloy in the
In the first step, the substrate is heated at a first temperature capable of preventing breakage of the base thin film to be created, and in the second step, the substrate is heated at a second temperature higher than the first temperature. While performing reflow while heating, in the first step, the sputtered particles of aluminum or aluminum alloy released from the target are ionized, and the ionized sputtered particles are accelerated by an electric field perpendicular to the substrate to be perpendicular to the substrate. It has a configuration in which a large amount of light is incident.
  In order to solve the above-mentioned problems, the invention according to claim 2 has a structure in which, in the structure of claim 1, the first temperature is a temperature in a range from room temperature to 150 ° C. or less.
  In order to solve the above-mentioned problems, a third aspect of the invention is that a thin film of a metal material is formed by sputtering on the surface of a substrate on which fine holes are formed, and the substrate is heated to reflow the thin film so that the metal is in the holes. A high-temperature reflow sputtering apparatus that buryes material and flattens holes,
Sputtering chamber equipped with an exhaust system, a target provided to expose the surface to be sputtered in the sputtering chamber, a sputtering power source for sputtering the target, and sputtered particles released from the target by sputtering reach A substrate holder for placing the substrate at a predetermined position in the sputtering chamber, and a heater for heating the substrate placed at the predetermined position;
  The substrate holder includes a pressurization gas introduction system for introducing a pressurization gas into the recess, and an electrostatic adsorption mechanism for adsorbing the substrate to the substrate holder by static electricity. And
  The heater heats the substrate at a low first temperature at which the base thin film is prevented from being interrupted in the first step of forming the base thin film of the metal material on the side and bottom surfaces of the hole, and after the first step In the second step, the substrate is heated at a second temperature higher than the first temperature to further reflow the metal material thin film to be deposited in the hole,
  Further, ionizing means for ionizing the sputtered particles, and electric field setting means for setting the electric field perpendicular to the substrate and accelerating the ionized sputtered particles to enter the substrate vertically are provided, In the first step, it is possible to create the base thin film by ionization sputtering,
  The electrostatic adsorption mechanism and the pressurizing gas introduction system do not operate in the first step but operate in the second step.
  In order to solve the above problem, according to a fourth aspect of the present invention, in the configuration of the third aspect, the electrostatic adsorption mechanism operates prior to the pressurizing gas introducing means in the second step. It has the structure of being a thing.
  In order to solve the above problem, the invention according to claim 5 is the configuration according to claim 3 or 4, wherein the target is made of aluminum or an aluminum alloy, and the first temperature is from room temperature to 150 ° C. or less. It has a configuration that there is.
  In order to solve the above problem, the invention according to claim 6 is the configuration according to claim 1 or 2, wherein the second step is performed.The second temperature in is 300 ° C. or higher and 450 ° C. or lower.It has the structure of.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
FIG. 1 is a plan view showing a schematic configuration of a high-temperature reflow sputtering apparatus according to an embodiment of the present invention. The apparatus of the present embodiment is a multi-chamber type apparatus, and a separation chamber 1 disposed in the center,Separation chamber 1A plurality of processing chambers 2, 3, 4, 5, 6 and two load lock chambers 7 provided around the chamber are arranged. Each of the chambers 1, 2, 3, 4, 5, 6, and 7 is a vacuum container that is evacuated by a dedicated or dual-purpose exhaust system. Further, gate valves 10 are respectively provided at connection points of the chambers 2, 3, 4, 5, 6, and 7 with respect to the separation chamber 1.
[0012]
A conveyance mechanism 11 is provided in the separation chamber 1. The transport mechanism 11 takes out the substrates 9 one by one from one load lock chamber 7 and sends them to the respective processing chambers 2, 3, 4, 5, 6 for sequential processing. And after finishing the last process, it returns to the other load lock chamber 7. FIG.
As the transport mechanism 11, an articulated robot having an arm for placing and holding the substrate 9 at the tip is preferably used. It is preferable to provide two arms so that the two substrates 9 can be moved independently at the same time because the transfer efficiency is improved.
The separation chamber 1 is evacuated by an exhaust system (not shown) and is always 10^-7-10^-8A vacuum pressure of about Torr is maintained. Therefore, a mechanism that can operate under this vacuum pressure is adopted as the transport mechanism 11.
[0013]
Next, the configuration of the sputtering chamber 2 will be described with reference to FIG. FIG. 2 is a schematic front view showing the configuration of the sputtering chamber 2 shown in FIG.
The sputter chamber 2 includes an exhaust system 21 that exhausts the inside and a sputter chamber 2.Sputtered surface 220Provided to exposeTarget 22A sputtering power source 23 for sputtering the target 22, a substrate holder 24 for placing the substrate 9 at a predetermined position in the sputtering chamber 2 where the material of the target 22 released by sputtering reaches, A process gas introduction system 25 for introducing a predetermined process gas into the substrate 9 and a heater 26 provided in the substrate holder 24 so as to heat the substrate 9 to a predetermined temperature are provided.
[0014]
The sputter chamber 2 is an airtight container formed of stainless steel or the like, and is electrically grounded. A gate valve 10 is provided in the sputter chamber 2, and the substrate 9 is carried into and out of the atmosphere via the transfer chamber 1 and the load lock chamber 7.
The exhaust system 21 includes a plurality of stages of vacuum pumps 211 such as a turbo molecular pump and a cryopump.^-9It is configured to be able to exhaust to about Torr. The exhaust system 21 is provided with an exhaust speed regulator 212 (not shown) such as a variable orifice, and can exhaust at a predetermined exhaust speed.
[0015]
The target 22 is attached to the sputter chamber 2 via an insulating material 221. In this embodiment, the target 22 is made of aluminum or an aluminum alloy.
The sputtering power source 23 applies a negative high voltage of about −500 to −700 V to the target 22. Due to this negative high voltage, a DC electric field is set between the target 22 and the substrate holder 24 and the like, and sputter discharge occurs.
[0016]
A magnet mechanism 222 is provided behind the target 22. The magnet mechanism 222 achieves magnetron discharge. Specifically, the magnet mechanism 222 surrounds the center magnet 223 and the center magnet 223.CircumferentialThe peripheral magnet 224 includes a central magnet 223 and a plate-like yoke 225 to which the peripheral magnet 224 is fixed. Between the center magnet 223 and the peripheral magnet 224, an arch-shaped magnetic force line 226 that penetrates the target 22 is set. Electrons are confined in a region surrounded by the magnetic force lines 226 and the sputtering target surface 220 of the target 22, and neutral gas molecules are ionized with high efficiency. For this reason, sputter discharge is maintained efficiently, and many sputtered particles are released, so that a high deposition rate can be obtained.
Further, the direction of the DC electric field set by the sputtering power source 23 is perpendicular to the surface to be sputtered 220 of the target 22. Accordingly, the magnetic field and the electric field are orthogonal to each other in the vicinity of the top of the arched magnetic field line 226, and a magnetron discharge is achieved. That is, electrons move in a magnetron motion and circulate around the center axis of the target 22 to further improve the efficiency of sputtering discharge.
[0017]
A process gas necessary for the sputter discharge is introduced by the process gas introduction system 25. The process gas introduction system 25 connects a gas cylinder 250 that stores a predetermined gas, and the gas cylinder 250 and the sputter chamber 2.Piping 251Provided aboveValve 252AndFlow rate regulator 253Etc. In addition, when sputter discharge is maintained only by ionization of sputtered particles emitted from the target 22, the process gas may not be introduced.
[0018]
A heater 26 such as a radiant heating method is provided inside the substrate holder 24. As the heater 26, for example, a radiation heating lamp of about 1 kW can be used. As another configuration of the heater 26, a resistance heating type heater may be embedded in the substrate holder 24.
[0019]
Further, a recess 240 is formed on the substrate placement surface of the substrate holder 24, and the substrate holder 24 has a gas introduction path 241 for introducing a pressurizing gas into the recess 240. Further, a gas introduction system 242 for boosting is connected to the gas introduction path 241. As gas for pressurization,Ar, hydrogen or heliumIs used.
[0020]
In the apparatus of this embodiment, the substrate 9 isStatic electricityAn electrostatic chucking mechanism 243 for chucking onto the substrate holder 24 is provided. The electrostatic adsorption mechanism 243 includes a pair of adsorption electrodes 246 embedded in a dielectric block 244 provided as a part of the substrate holder 24, and an adsorption power source 247 that applies a DC voltage between the pair of adsorption electrodes 246. And is composed mainly of.
The dielectric block 244 is made of a dielectric material such as alumina and is bonded to the metal holder main body 245 with good adhesion. The dielectric block 244 and the holder body 245 are joined using an adhesive or the like, but if a cushioning material such as a thin carbon sheet is interposed therebetween, the two are joined with good adhesion, and the thermal conductivity is good. To be kept.
[0021]
The suction power supply 247 is configured to apply a voltage of, for example, about 300 to 1 kV between the pair of suction electrodes 246. This voltage causes dielectric polarization in the dielectric block 244 and induces static electricity on the surface. Due to this static electricity, the substrate 9 is electrostatically attracted to the dielectric block 244. As a result, the adhesion of the substrate 9 to the substrate holder 24 is improved, and the pressurization gas leakage from the recess 240 is effectively prevented. For this reason, a sufficient differential pressure is formed between the atmosphere in the sputter chamber 2 and the recess 240, and the recess 240 is maintained at a predetermined high pressure while maintaining the sputter chamber 2 at a predetermined vacuum pressure. . Therefore, the heat from the heater 26 is efficiently transmitted to the substrate 9 via the substrate holder 24, and the substrate 9 can be rapidly heated.
[0022]
A supplementary description will be given of the shape of the recess 240 formed on the substrate placement surface of the substrate holder 24. FIG. 3 is a schematic plan view for explaining the shape of the recess 240 of the substrate holder 24 shown in FIG.
As shown in FIGS. 2 and 3, in the apparatus according to the present embodiment, the concave portion 240 is formed by an annular convex portion extending along the periphery and small cylindrical convex portions scattered inside the annular convex portion. Has been. The outlet 248 of the gas introduction path 241 isNear the center of the substrate holder 24The gas introduced into the concave portion 240 from the outlet 248 diffuses through the cylindrical convex portions and fills the concave portion 240.
[0023]
Such a configuration of the recess 240 serves to increase the area of the substrate placement surface that directly contacts the substrate 9. That is, if the concave portion 240 has a simple shape such as a circular shape in plan view, the area of the portion of the substrate placement surface that directly contacts the substrate 9 is reduced. For this reason, the substrate 9 may not be sufficiently adsorbed when adsorbed by the electrostatic adsorption mechanism 243. However, if the area of the portion directly in contact with the substrate 9 is increased by forming the concave portion 240 as in the present embodiment, the overall adsorption force increases, and the substrate 9 can be adsorbed sufficiently reliably.
[0024]
The high-temperature reflow sputtering apparatus according to this embodiment is characterized mainly by ionization means 27 for ionizing sputtered particles emitted from the target 22 by sputtering and sputtered particles ionized by setting an electric field perpendicular to the substrate 9. And an electric field setting means 28 for accelerating the incidence of light vertically on the substrate 9.
[0025]
The ionization means 27 is adapted to ionize sputtered particles with high-frequency energy, and includes an ionization electrode 271 provided in the sputtering chamber 2 and a high-frequency power source 272 that supplies high-frequency energy to the ionization electrode 271. .
The ionization electrode 271 is provided so as to surround the flight space of sputtered particles from the target 22 to the substrate 9. As the ionization electrode 271, for example, a metal mesh formed in a cylindrical shape or a coil shape is used.
As the high frequency power supply 272, for example, a power supply having a frequency of about 13.56 MHz and an output of about 1 kW is used. The high frequency electric field set in the sputter chamber 2 by the ionization electrode 271 forms a plasma P ′ by high frequency discharge separately from the plasma P by sputter discharge. The neutral sputtered particles emitted from the target 22 collide with ions and electrons in the plasma P ′ when passing through the plasma P ′ and are ionized (hereinafter referred to as ionized sputtered particles).
[0026]
On the other hand, the electric field setting means 28 is configured to set an electric field perpendicular to the substrate 9 in the sputtering chamber 2 and to cause the ionized sputtered particles to enter the substrate 9 perpendicularly. As the electric field setting means 28, in this embodiment, a high frequency power supply 281 for a substrate that applies a high frequency voltage to the substrate holder 24 and applies a negative self-bias voltage to the substrate 9 by the interaction between the high frequency and the plasma P ′ is adopted. ing. As the substrate high-frequency power supply 281, for example, a power supply having a 13.56 MHz output of about 300 W can be used.
A matching unit 282 is provided between the high frequency power supply 281 for the substrate and the substrate holder 24. Further, when both the substrate 9 and the substrate holder 24 are conductors, a predetermined capacitor is provided in the high-frequency transmission path, and a high-frequency voltage is applied to the substrate 9 via the capacitor.
[0027]
When a high-frequency voltage is applied to the substrate 9 through a capacitance such as a capacitor, electrons and positive ions in the plasma P ′ act on the charge and discharge of the capacitance, and negative self-force is applied to the substrate 9 due to the difference in mobility between the electrons and positive ions. A bias potential is generated. The space potential of the plasma P ′ is almost the ground potential or a positive potential of about 20 volts, and the potential gradually decreases toward the substrate 9 between the substrate 9 where the negative self-bias potential is generated and the plasma P ′. An electric field is set. The direction of the electric field is perpendicular to the substrate 9, and positively ionized sputtered particles are accelerated by the electric field and are incident on the substrate 9 in a large amount almost perpendicularly.
[0028]
Next, returning to FIG. 1, the configuration of another processing chamber will be described.
One of the other processing chambers is configured as an etching chamber 3 that cleans the substrate 9 by sputter etching before film formation. A natural oxide film or a protective film may be formed on the surface of the substrate 9 carried into the apparatus. If such a film is formed as it is, there is a problem that the electrical characteristics of the thin film to be produced are deteriorated or the adhesion of the thin film is deteriorated. Therefore, prior to film formation, the surface of the substrate 9 is sputter-etched to remove the natural oxide film and the protective film.
The etching chamber 3 includes means for introducing a gas for sputter etching such as argon, means for forming a plasma by supplying high-frequency energy to the introduced gas, and extracting positive ions from the plasma to the substrate 9. And means for setting an electric field to be incident. Positive ions in the plasmaOf substrate 9When incident on the surface, the natural oxide film and protective film on the surface are removed by sputter etching. As a result, the clean surface of the original material of the substrate 9 is exposed.
[0029]
Another one of the other processing chambers is configured as a preheat chamber 4 for preheating the substrate 9 before film formation. The preheat chamber 4 includes a substrate holder (not shown) similar to the substrate holder 24 described above. A heater such as a radiant heating method is provided in the substrate holder so that the substrate 9 placed on the substrate holder can be heated to a predetermined temperature. In addition, the substrate 9 is electrostatically attracted to the substrate holder to improve the thermal conductivity, or a gas for improving the thermal conductivity is supplied to the gap between the substrate holder and the substrate 9.There are things to do.
The main purpose of the preheating is to degas, that is, to release the stored gas of the substrate 9 by heating. If this degassing is not performed, a rapid gas release occurs from the substrate 9 during the high-temperature reflow sputtering in the sputtering chamber 2, and this gas release causesInside the thin filmA cavity is created. When such a cavity is generated, the wiring resistance may increase, or in the worst case, it may cause a circuit defect such as disconnection. The heating temperature of the substrate 9 for degassing is about 400 to 500 ° C., and the heating time is about 60 to 180 seconds.
[0030]
Further, another one of the other processing chambers is configured as a barrier film creation chamber 5 for creating a barrier film as a base film for the high-temperature reflow sputtering film. As the barrier film, a titanium film is usually employed and is formed by sputtering. Therefore, the barrier film creation chamber 5 is configured to perform sputtering using a titanium target. The configuration is substantially the same as that of the sputtering chamber shown in FIG. 2 except that a titanium target is used. However, the temperature of the substrate 9 during sputtering is about 400 ° C.
[0031]
Further, another one of the other processing chambers is configured as an antireflection film forming chamber 6 for forming an antireflection film to be laminated on the high temperature reflow sputtering film. The antireflection film is for preventing reflected light from the substrate 9 when the substrate 9 is exposed in a later lithography process. As the antireflection film, a titanium nitride film is usually employed and is formed by sputtering. The antireflection film creation chamber 6 is configured to perform sputtering by using a target made of titanium and introducing nitrogen gas. The configuration is substantially the same as the sputtering chamber shown in FIG. 2 except that a titanium target is used and nitrogen gas is introduced.
In the antireflection film forming chamber 6, titanium nitride formed by reacting with nitrogen on the surface of the titanium target is released by sputtering, or titanium released from the target reacts with nitrogen to become titanium nitride. A titanium nitride thin film is deposited on the surface of the substrate 9. During the film formation, the substrate 9 is not heated by the heater and is at a temperature of about 30 ° C.
[0032]
Next, while explaining the operation of the high temperature reflow sputtering apparatus of the embodiment according to the above configuration, an embodiment of the invention of the high temperature reflow sputtering method will be described.
In FIG. 1, a predetermined number of substrates 9 are moved to oneLoad lock chamber 7And is accommodated in a cassette 71 in the load lock chamber 7. The transport mechanism 11 takes out one substrate 9 from the one load lock chamber 7 and first sends it to the etching chamber 3. In the etching chamber 3, the natural oxide film and the protective film on the surface are removed as described above. Next, the transport mechanism 11 sends the substrate 9 to the preheat chamber 4. The substrate 9 is preheated in the preheat chamber 4 and degassed.
Thereafter, the transport mechanism 11 sends the substrate 9 to the barrier film creation chamber 5. In the barrier film creation chamber 5, as described above, a titanium target is sputtered to form a titanium thin film on the surface of the substrate 9 as a barrier film.
[0033]
Next, the transport mechanism 11 sends the substrate 9 to the sputter chamber 2. In the sputtering chamber 2, high-temperature reflow sputtering is performed as follows to create an aluminum film on the surface of the substrate 9 and embed it.
The operation in the sputter chamber 2 is a major feature of the method of the embodiment. The first major feature is that the process is performed in two steps with different substrate temperatures. That is, in the first step, the substrate 9Low temperatureIn the second step, the temperature of the substrate 9 is kept high. The second major feature is that in the first step, film formation is performed in the hole with a bottom coverage rate by ionization sputtering.
[0034]
More specifically, after the substrate 9 is placed on the substrate holder 24 by the transport mechanism 11, the gate valve 10 is closed. In the substrate holder 24Heater 26Is always operating, but the electrostatic adsorption mechanism 243 and the pressure-increasing gas introduction system 242 are not operating. Therefore, the heat transfer from the substrate holder 24 is inefficient and the temperature rise of the substrate 9 when placed on the substrate holder 24 is small. For example, the substrate 9 remains heated to about 100 ° C.
The first step is performed in this low temperature state. That is, the process gas gas system 25 is operated, and argon gas as a process gas is introduced into the sputtering chamber 2. Of the process gas introduction system 25Flow rate regulator 253Therefore, the flow rate of the argon gas is adjusted to about 10 to 30 cc / min, and the exhaust speed is adjusted by the exhaust speed adjuster 212 of the exhaust system 21 to keep the pressure in the sputter chamber 2 at about 1 to 3 mTorr.
[0035]
In this state, the sputtering power source 23 is operated to cause sputtering discharge in the argon gas to sputter the target 22. The voltage applied to the target 22 is about 600V. At the same time, the high frequency power supply 272 of the ionization means 27 and the high frequency power supply 281 of the electric field setting means 28 are operated. High frequency power of 13.56 MHz and 500 W is applied to the ionization electrode 271, and high frequency power of 13.56 MHz and 100 W is applied to the substrate holder 24 from a high frequency power supply 281.
The ionized sputtered particles generated when passing through the plasma P ′ formed by the ionizing means 27 are accelerated by the electric field set by the electric field setting means 28 and are incident on the substrate 9 at an angle close to vertical. As a result, it becomes easy to reach the bottom and side surfaces of the fine holes formed on the surface of the substrate 9, and an aluminum thin film is formed with sufficient coverage on the bottom and side surfaces.
[0036]
Next, the second step is performed. First, the electrostatic attraction mechanism 243 is operated to electrostatically attract the substrate 9 to the substrate holder 24. Thereafter, the pressurization gas introduction system 242 is operated to introduce Ar gas, hydrogen gas, or helium gas into the recess 240 on the surface of the substrate holder 24 to increase the pressure in the recess 240 to about 10 Torr. Note that if the electrostatic adsorption mechanism 243 and the pressurization gas introduction system 242 are operated simultaneously, or if the pressurization gas introduction system 242 is operated first, the gas flows between the substrate 9 and the substrate holder 24, and the substrate 9. May float and electrostatic adsorption may not operate sufficiently.
[0037]
When the electrostatic adsorption mechanism 243 and the boosting gas introduction system 242 are operated in this way, the heat of the substrate holder 24 given by the heater 26 is efficiently transferred to the substrate 9 and the temperature of the substrate 9 rises. Although the electrostatic adsorption mechanism 243 and the pressure-increasing gas introduction system 242 may be operated at all times and the temperature control may be performed by controlling the electric power supplied to the heater 26, there is a drawback that the temperature responsiveness of the substrate 9 is not good. . The temperature control of the substrate 9 by turning on / off the electrostatic adsorption mechanism 243 and the gas introduction system 242 for boosting is excellent in terms of responsiveness.
[0038]
The heater 26 is controlled by a heater control unit (not shown), and the temperature of the substrate 9 is maintained at a predetermined temperature higher than the temperature of the first step. This temperature is about 300 to 450 ° C. While maintaining this temperature, sputtering is continued, the deposited or deposited aluminum film is reflowed, and the hole is embedded. In the second step, the ionization means 27 and the electric field setting means 28 may or may not be operated.
[0039]
In this way, after high-temperature reflow sputtering is performed in the sputtering chamber 2, the substrate 9 is transferred to the antireflection film forming chamber 6. Then, an antireflection film made of titanium nitride is formed on the surface. Thereafter, the substrate 9 is cooled as necessary, and then transferred to the other load lock chamber 7.
[0040]
Now, in the operation described above, the operations of the ionization means 27 and the electric field setting means 28 in the first step of the high-temperature reflow sputtering are based on the following knowledge of the inventors. This point will be described in detail below with reference to FIG. FIG. 4 is a diagram for explaining the effect of the method and apparatus of the embodiment.
[0041]
First, the structure divided into the first and second two-stage processes described above contributes to the production of a high-quality high-temperature reflow sputtering film having no voids. That is, if sputtering is performed at a high temperature (for example, 500 ° C.) from the beginning without dividing into two stages, as shown in FIG. 4A, a melted thin film (hereinafter referred to as a reflow thin film) 91 is not embedded in the hole 90. A cavity 92 called a void is generated. This is considered to be because the wettability (affinity) of the reflow thin film 91 with respect to the inner surface of the hole 90 is not sufficient, and the reflow thin film 91 is retained by the surface tension.
[0042]
On the other hand, as described above, when the film is formed at a low temperature in the first step, the thin film 93 to be deposited is not melted greatly and is thinly deposited on the inner surface and the periphery of the hole 90 (hereinafter, this thin film is used as a base). Referred to as thin film 93). Then, when the film is formed while reflowing at a higher temperature in the subsequent second step, the reflow thin film 91 is melted on the base thin film 93, so that the wettability is high and the above-mentioned void 92 is not generated. (FIG. 4B). The temperature in this first step is preferably from room temperature to about 150 ° C. when aluminum or aluminum alloy is embedded. When the temperature is higher than 150 ° C., the base thin film 93 is interrupted, causing the void 92 to be generated.
[0043]
As described above, the configuration in which the base thin film 93 is formed in advance in the first and second steps is effective for preventing the generation of the void 92. However, even in this case, the substrate 9 is formed in the second step. It is necessary to heat to about 500 degreeC. If the temperature of the substrate 9 is set to about 300 ° C. in the second step, a void 92 is also generated inside the hole 90 (FIG. 4C). This is considered to be because the speed at which the reflow thin film 91 diffuses on the base thin film 93 depends on the temperature, and the diffusion becomes insufficient at a low temperature.
[0044]
However, according to the inventor's research, it has been found that when the coverage in the hole 90 of the base thin film 93 is increased, film formation without the generation of voids 92 can be performed without increasing the temperature so much. That is, as shown in FIG. 4C, when the base thin film 93 is formed by normal sputtering, the base thin film 93 is deposited on the side surface and bottom surface of the hole 90 only thinner than the surface around the hole 90. On the other hand, as described above, when the sputtered particles are ionized, the sputtered particles easily reach the hole 90 and the film thickness on the side surface and the bottom surface of the hole 90 is increased. When the base thin film 93 in the hole 90 is thus thickened, the reflow thin film 91 is sufficiently diffused even at a relatively low temperature of about 300 ° C., and as shown in FIG. Become.
[0045]
Based on such knowledge, the sputter chamber 2 in the apparatus of this embodiment includes an ionization means 27 and an electric field setting means 28. In the method of this embodiment, the sputtered particles are ionized in the first step to form the substrate 9. So that it is incident vertically.
Note that the high-temperature reflow sputtering is used for, for example, Al flattening on a tungsten film in addition to the above-described filling and filling of interlayer through holes.
[0046]
【The invention's effect】
  As described above, according to the invention of each claim of the present application, since the film thickness of the base thin film in the hole becomes sufficiently thick, the voids can be formed even if the temperature does not exceed 500 ° C. in the second step. High temperature reflow sputtering can be performed. For this reason, it becomes suitable for manufacture of the next-generation device in which miniaturization and high functionality progress. Claims3According to the invention, in addition to the above effects, the temperature of the substrate is increased by the operation of the electrostatic adsorption mechanism and the pressure-increasing gas introduction system. Claims4According to the invention, in addition to the above effect, there is an effect that there is no fear that the electrostatic adsorption of the substrate becomes insufficient.
[Brief description of the drawings]
FIG. 1 is a plan view showing a schematic configuration of a high-temperature reflow sputtering apparatus according to an embodiment of the present invention.
2 is a schematic front view showing a configuration of a sputtering chamber 2 shown in FIG. 1. FIG.
3 is a schematic plan view for explaining the shape of a recess 240 of the substrate holder 24 shown in FIG.
FIG. 4 is a diagram for explaining the effect of the method and apparatus of the embodiment.
FIG. 5 is a front view showing a schematic configuration of a conventional high-temperature reflow sputtering apparatus.
[Explanation of symbols]
1 Transfer chamber
10 Gate valve
11 Transport mechanism
2 Sputter chamber
21 Exhaust system
22 Target
23 Sputtering power supply
24 Substrate holder
240 recess
242 Gas introduction system for pressurization
243 Electrostatic adsorption mechanism
25 Process gas introduction system
26 Heater
3 Etching chamber
4 Preheat chamber
5 Barrier film creation chamber
6 Antireflection film creation chamber
7 Load lock chamber
9 Board
90 holes
91 Reflow thin film
92 Void
93 Base thin film

Claims (6)

A high-temperature reflow sputtering method in which aluminum or an aluminum alloy is embedded in fine holes formed in a substrate,
A first step of thinly forming a base thin film of aluminum or aluminum alloy on the side surface and bottom surface of the hole, and after the first step, a thin film of aluminum or aluminum alloy is further deposited and reflowed into the hole. A second step of embedding aluminum or aluminum alloy in the
In the first step, the substrate is heated at a first temperature capable of preventing breakage of the base thin film to be created, and in the second step, the substrate is heated at a second temperature higher than the first temperature. While performing reflow while heating, in the first step, the sputtered particles of aluminum or aluminum alloy released from the target are ionized, and the ionized sputtered particles are accelerated by an electric field perpendicular to the substrate to be perpendicular to the substrate. A high-temperature reflow sputtering method, wherein a large amount of light is incident.   The high-temperature reflow sputtering method according to claim 1, wherein the first temperature is a temperature in a range from room temperature to 150 ° C. or less. This is a high-temperature reflow sputtering system that creates a thin film of metal material by sputtering on the surface of a substrate on which fine holes are formed, heats the substrate, reflows the thin film, embeds the metal material in the holes, and flattens the holes. And
Sputtering chamber equipped with an exhaust system, a target provided to expose the surface to be sputtered in the sputtering chamber, a sputtering power source for sputtering the target, and sputtered particles released from the target by sputtering reach A substrate holder for placing the substrate at a predetermined position in the sputtering chamber, and a heater for heating the substrate placed at the predetermined position;
The substrate holder includes a pressurization gas introduction system for introducing a pressurization gas into the recess, and an electrostatic adsorption mechanism for adsorbing the substrate to the substrate holder by static electricity. And
The heater heats the substrate at a low first temperature at which the base thin film is prevented from being interrupted in the first step of forming the base thin film of the metal material on the side and bottom surfaces of the hole, and after the first step In the second step, the substrate is heated at a second temperature higher than the first temperature to further reflow the metal material thin film to be deposited in the hole,
Further, ionizing means for ionizing the sputtered particles, and electric field setting means for setting the electric field perpendicular to the substrate and accelerating the ionized sputtered particles to enter the substrate vertically are provided, In the first step, it is possible to create the base thin film by ionization sputtering,
The high-temperature reflow sputtering apparatus, wherein the electrostatic adsorption mechanism and the pressurizing gas introduction system do not operate in the first step but operate in the second step.   4. The high-temperature reflow sputtering apparatus according to claim 3, wherein the electrostatic adsorption mechanism operates in the second step prior to the pressurizing gas introduction unit.   5. The high-temperature reflow sputtering apparatus according to claim 3, wherein the target is made of aluminum or an aluminum alloy, and the first temperature is from room temperature to 150 ° C. or less. 3. The high-temperature reflow sputtering method according to claim 1 , wherein the second temperature in the second step is 300 ° C. or higher and 450 ° C. or lower .

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