Thin film deposition method and thin film deposition system

Abstract

To form a tungsten-containing amorphous alloy film having tensile stress.SOLUTION: A film deposition method comprises steps of: forming a tungsten-containing amorphous alloy film on a substrate; and heating the substrate at a temperature without crystallizing the alloy film.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present disclosure relates to a film forming method and a film forming system.

Background Art

[0002] Patent Document 1 discloses a method for manufacturing a W-containing film, comprising a step of forming a W (tungsten)-containing film precursor on a substrate, a step of forming an insulating film on the W-containing film precursor, a step of performing heat treatment after forming the insulating film to modify the W-containing film precursor into a W-containing film, and a step of removing the insulating film.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The technology according to the present disclosure forms an amorphous alloy film containing tungsten and having tensile stress.

Means for Solving the Problems

[0005] One aspect of the present disclosure is a film forming method including: a first step of forming an amorphous film containing tungsten on a substrate without performing heating and cooling; and a second step of heating the substrate at a temperature at which the film does not crystallize to form the film having tensile stress.

Effects of the Invention

[0007] [Figure 1] This figure shows the relationship between the film stress of a tungsten silicide film formed by sputtering and the flow rate of Ar gas used as the sputtering gas. [Figure 2] This figure shows the relationship between the electrical resistivity of a tungsten silicide film formed by sputtering and the flow rate of Ar gas used as the sputtering gas. [Figure 3] This is a plan view showing a schematic configuration of the wafer processing system as a film deposition system according to this embodiment. [Figure 4] This is a longitudinal cross-sectional view showing the general configuration of the film deposition apparatus. [Figure 5] This is a longitudinal cross-sectional view showing a schematic configuration of the load lock device. [Figure 6] This is a flowchart illustrating an example of a film deposition process using wafer processing system 1. [Figure 7] This figure shows the results of tests conducted to evaluate the change in film stress due to heating of a tungsten silicide film. [Modes for carrying out the invention]

[0008] In the manufacturing process of semiconductor devices, a tungsten silicide (WSi) film may be formed on a substrate such as a semiconductor wafer (hereinafter referred to as "wafer") for use as a hard mask (HM) for etching. WSi films have a higher selectivity for etching silicon oxide (SiO2) films compared to silicon (Si) films and titanium nitride films, and can be made thinner, making them advantageous for microfabrication. Furthermore, by making WSi films amorphous, roughness caused by crystals and grain boundaries can be reduced when processed into HM (High Mould).

[0009] By the way, for HM films, not just WSi films, it is generally required that the internal stress be tensile stress rather than compressive stress. This is because if the stress is compressive, distortion (wiggling) may occur in the pattern when processed into HM.

[0010] When WSi films are formed by sputtering, it is sometimes possible to change the film stress of the WSi film to tensile stress by increasing the flow rate, i.e., the pressure, of the sputtering gas (working gas). Specifically, this can be done as follows:

[0011] Figure 1 shows the relationship between the film stress of a WSi film formed by sputtering and the flow rate of Ar gas used as the sputtering gas. In Figure 1, the horizontal axis represents the Ar gas flow rate, and the vertical axis represents the film stress. Figure 2 shows the relationship between the electrical resistivity of a WSi film formed by sputtering and the flow rate of Ar gas used as the sputtering gas. In both Figures 1 and 2, the horizontal axis represents the Ar gas flow rate. In Figure 1, the vertical axis represents the film stress of the WSi film, and in Figure 2, the vertical axis represents the electrical resistivity of the WSi film. Figures 1 and 2 show the results when the W concentration of the formed WSi film is 80%.

[0012] As shown in Figure 1, when the W concentration of the formed WSi film is 80%, if the Ar gas flow rate during film formation is 50 sccm or less, the film stress of the WSi film is compressive stress, but if it is 150 sccm, the film stress is tensile stress. However, as shown in Figure 2, when the Ar gas flow rate during film formation is 50 sccm or less, the electrical resistivity of the WSi film is low, but when it is 150 sccm, the electrical resistivity is high. A high electrical resistivity of the WSi film means that the density of the WSi film is low, and a low density leads to a low selectivity ratio as described above. Also, if the flow rate of sputtering gas such as Ar gas during film formation is high, the WSi film will not be amorphous. The points mentioned above are also true for tungsten (W)-containing alloy films other than WSi films.

[0013] Therefore, the technology according to the present disclosure forms an amorphous alloy film having a tensile stress and containing W.

[0014] Hereinafter, the film forming method and film forming system according to the present embodiment will be described with reference to the drawings. In the present specification and the drawings, elements having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

[0015] <Wafer Processing System> FIG. 3 is a plan view showing an outline of the configuration of a wafer processing system 1 as a film forming system according to the present embodiment.

[0016] The wafer processing system 1 has, for example, as shown in the figure, a carrier station 10 where a carrier C capable of accommodating a plurality of wafers K is carried in and out, and a processing station 11 provided with a plurality of film forming apparatuses 40 described later for performing a film forming process on the wafer K under reduced pressure, which are integrally connected. The carrier station 10 and the processing station 11 are connected via load lock apparatuses 12 and 13 as two heating apparatuses.

[0017] The load lock apparatuses 12 and 13 have a housing forming load lock chambers 12a and 13a configured to be able to switch the interior between an atmospheric pressure state and a vacuum state. The load lock apparatuses 12 and 13 are provided so as to connect an atmospheric pressure transfer device 20 and a vacuum transfer device 30 described later. In the present embodiment, the load lock apparatuses 12 and 13 also function as heating apparatuses for heating the wafer K. The same applies to the load lock apparatus 13. Details of the configuration of the load lock apparatus 12 will be described later.

[0018] ]<( The carrier station 10 has an atmospheric pressure transfer device 20 and a carrier mounting table 21. Note that the carrier station 10 may be further provided with an aligner (not shown) for adjusting the orientation of the wafer K.

[0019] The atmospheric pressure transport device 20 has a housing that forms an atmospheric transport chamber 22 in which the interior is under atmospheric pressure. The atmospheric transport chamber 22 is connected to the load lock chambers 12a and 13a of the load lock devices 12 and 13 via gate valves G1 and G2. Inside the atmospheric transport chamber 22, there is a transport mechanism 23 that transports wafers K between the load lock chambers 12a and 13a under atmospheric pressure.

[0020] The transport mechanism 23 has two transport arms 23a and 23b that hold the wafer K. Each of the transport arms 23a and 23b is composed of a multi-joint arm. The transport mechanism 23 is configured to transport the wafer K while holding it with either the transport arm 23a or 23b.

[0021] The carrier mounting table 21 is located on the side opposite to the load lock devices 12 and 13 in the atmospheric pressure transport device 20. In the illustrated example, the carrier mounting table 21 can accommodate multiple carriers C, for example, three. The wafers K inside the carriers C placed on the carrier mounting table 21 are transported in and out of the atmospheric transport chamber 22 by the transport arms 23a and 23b of the transport mechanism 23 of the atmospheric pressure transport device 20.

[0022] The processing station 11 includes a vacuum transfer device 30 and a plurality of film deposition devices 40.

[0023] The vacuum transfer device 30 has a housing that forms a vacuum transfer chamber 31 in which the interior is kept in a reduced-pressure state (vacuum state). The housing is configured to be airtight and is formed to have a substantially polygonal shape (hexagonal in the illustrated example) in plan view. The vacuum transfer chamber 31 is connected to the load lock chambers 12a and 13a of the load lock devices 12 and 13 via gate valves G3 and G4. A transfer mechanism 32 is provided inside the vacuum transfer chamber 31 for transferring wafers K between each film deposition apparatus 40 and the vacuum processing chamber 41 described later.

[0024] The transport mechanism 32 includes two transport arms 32a and 32b that hold the wafer K, and a base 32c that pivotally supports the base portions of each of the transport arms 32a and 32b. The transport mechanism 32 is configured to transport the wafer K while holding it with either the transport arm 32a or 32b.

[0025] On the outside of the housing that forms the vacuum transfer chamber 31 of the vacuum transfer device 30, a plurality of film deposition devices 40 and load lock devices 12 and 13 are arranged so as to surround the housing. The plurality of film deposition devices 40 and load lock devices 12 and 13 are arranged so as to face the side surfaces of the housing, respectively.

[0026] The film deposition apparatus 40 performs a film deposition process on the wafer K under reduced pressure. In this embodiment, each film deposition apparatus 40 forms an amorphous WSi film on the wafer K. Each film deposition apparatus 40 also has a housing that forms a vacuum processing chamber 41 in which the above predetermined processing is performed on the wafer K under reduced pressure. Each vacuum processing chamber 41 is connected to the vacuum transfer chamber 31 of the vacuum transfer apparatus 30 via a gate valve G5 which acts as a gate valve.

[0027] The wafer processing system 1 described above is equipped with a control device 50. The control device 50 is a computer equipped with, for example, a processor such as a CPU and memory, and has a program storage unit (not shown). The program storage unit stores a program that controls wafer processing in the wafer processing system 1. These programs may have been recorded on a computer-readable storage medium H and installed from the storage medium H to the control device 50.

[0028] <Film forming equipment 40> Figure 4 is a longitudinal cross-sectional view showing a schematic configuration of the film deposition apparatus 40.

[0029] The film deposition apparatus 40 includes a housing 100 as a processing container, as shown in the figure. The housing 100 is configured to allow for reduced pressure inside and houses the wafer K. It is made of, for example, aluminum and is connected to ground potential. An exhaust device 60 for reducing the pressure of the space inside the housing 100 is connected to the bottom of the housing 100. The exhaust device 60 has a vacuum pump (not shown) or the like and is connected to the housing 100 via, for example, an APC valve 101.

[0030] Furthermore, a wafer K loading / unloading port 102 is formed in the side wall of one side of the housing 100 (the positive side in the X direction in the figure), and a gate valve G5 for opening and closing the loading / unloading port 102 is provided in this port 102.

[0031] A mounting table 110 is provided inside the housing 100 as a substrate support section. The mounting table 110 supports the wafer K placed on it. The mounting table 110 has an electrostatic chuck 111 and a base portion 112.

[0032] The electrostatic chuck 111 has, for example, a dielectric film and electrodes provided as an inner layer of the dielectric film, and is provided on the base portion 112. A DC power supply (not shown) is connected to the electrodes of the electrostatic chuck 111. The wafer K placed on the electrostatic chuck 111 is held in place by the electrostatic attraction force generated by applying a DC voltage from the DC power supply to the electrodes.

[0033] The base portion 112 is formed in a disc shape using, for example, aluminum. The mounting stage 110 may have a temperature control mechanism for heating or cooling the wafer K, or at least one of the other. The temperature control mechanism may be, for example, a resistance heating heater or a flow path for a cooling medium. The temperature control mechanism may also be provided on the electrostatic chuck 111 or on the base portion 112.

[0034] Furthermore, the mounting base 110 is connected to a rotation / movement mechanism 113. The rotation / movement mechanism 113 includes, for example, a support shaft 114 and a drive unit 115. The support shaft 114 extends vertically so as to penetrate the bottom wall of the housing 100. A sealing member SL1 is provided between the support shaft 114 and the bottom wall of the housing 100. The sealing member SL1 is a member that seals the space between the bottom wall of the housing 100 and the support shaft 114 so that the support shaft 114 can rotate and move up and down, and is, for example, a magnetic fluid seal. The upper end of the support shaft 114 is connected to the center of the lower surface of the mounting base 110, and the lower end is connected to the drive unit 115. The drive unit 115 has a drive source such as a motor and generates a driving force to rotate and move the support shaft 114 up and down. As the support shaft 114 rotates around its axis AX, the mounting base 110 rotates around the axis AX, and as the support shaft 114 moves up and down, the mounting base 110 moves up and down.

[0035] Above the mounting base 110, there are multiple holders (cathodes) 121 made of conductive material that hold a metal target 120. In this embodiment, there are two holders 121.

[0036] The holder 121 holds the target 120 so that the target 120 is positioned inside the housing 100. The holder 121 is attached to the ceiling of the housing 100. Through-holes are formed at the mounting positions of each holder 121 in the housing 100. In addition, insulating members 103 are provided on the inner wall surface of the housing 100 so as to surround the through-holes. Each holder 121 is attached to the housing 100 via the insulating members 103 so as to close the through-holes.

[0037] The holder 121 holds the target 120 facing forward so that the target 120 faces the mounting base 110. In one embodiment, each target 120 contains both W and Si. In this embodiment, the tungsten concentration and silicon concentration of each target 120 are adjusted so that the film formed on the wafer K is an amorphous WSi film. In this embodiment, both of the two targets 120 may be used during film formation, or only one of them may be used.

[0038] A power supply 122 is connected to each holder 121, and a negative DC voltage is applied from the power supply 122. Alternatively, an AC voltage may be applied instead of the negative DC voltage.

[0039] Furthermore, a magnet unit 123 is provided on the back side of each holder 121, at a position that is outside the housing 100. The magnet unit 123 forms a magnetic field that leaks to the front side of the target 120 held by the corresponding holder 121.

[0040] The magnet unit 123 is connected to the moving mechanism 124. The moving mechanism 124 swings the magnet unit 123 in a predetermined direction (the Y direction in Figure 4) along the back surface of the corresponding holder 121. The moving mechanism 124 has a drive unit (not shown) that includes a drive source (e.g., a motor) that generates the driving force to swing the magnet unit 123.

[0041] Furthermore, the film deposition apparatus 40 is equipped with a gas supply unit 130 that supplies gas into the housing 100. The gas supply unit 130 supplies inert gases such as argon (Ar) gas and krypton (Kr) gas, which are sputtering gases, into the housing 100.

[0042] The gas supply unit 130 includes, for example, a gas source 131, a flow controller 132 such as a mass flow controller, and a gas introduction unit 133. The gas source 131 stores sputtering gas. Each gas source 131 is connected to the gas introduction unit 133 via the flow controller 132. The gas introduction unit 133 is a component that introduces gas from the gas source 131 into the housing 100.

[0043] The exhaust device 60, the rotating / moving mechanism 113, the power supply 122, the moving mechanism 124, and the gas supply unit 130 are controlled by the control device 50.

[0044] <Load lock device 12> Next, the load lock device 12 will be explained using Figure 5. Figure 5 is a longitudinal cross-sectional view showing a schematic configuration of the load lock device 12. Note that the configuration of the load lock device 13 is the same as that of the load lock device 12, so its explanation will be omitted.

[0045] The load lock device 12 includes a housing 200 as a processing container, as shown in the figure. The housing 200 is configured to allow for reduced pressure inside and houses the wafer K, and is made of, for example, aluminum. The housing 200 has two opposing side walls, each having an inlet / outlet 201a and 201b, and gate valves G1 and G3 are provided at the inlet / outlet 201a and 201b, respectively.

[0046] An exhaust port 202 is formed at the bottom of the housing 200 to reduce the pressure inside the housing 200. An exhaust device 70, which includes a vacuum pump (not shown), is connected to the exhaust port 202. Furthermore, an air inlet 203 is formed in the bottom wall of the housing 200 to return the inside of the housing 200 to an atmospheric pressure atmosphere. A gas supply mechanism 210 is connected to the air inlet 203 to supply an inert gas, such as N2 gas.

[0047] Furthermore, multiple rod-shaped support pins 220 are provided inside the housing 200 to support the wafer K. Each support pin 220 is positioned to extend upward from the bottom of the housing 200.

[0048] Furthermore, an opening 204 is formed in the upper part of the housing 200, and an optical window 205 is provided to cover this opening 204. The optical window 205 is made of a material that transmits light from the light irradiation unit described later.

[0049] On the outside of the housing 200, above the optical window 205, is a heating unit 230 that heats the wafer K, which is supported by the support pins 220, with light. The heating unit 230 is positioned to face the support pins 220 through the optical window 205.

[0050] The heating section 230 has a light irradiation unit U. The light irradiation unit U heats the wafer K, which is supported by the support pins 220, by irradiating it with light. In plan view, the light irradiation unit U has a shape corresponding to the wafer K, and is formed, for example, in a circular shape in plan view. This light irradiation unit U has, for example, multiple LEDs 231 that are directed toward the wafer K as light-emitting elements.

[0051] Each LED 231 shines light toward the wafer K. Each LED 231 emits light capable of heating the wafer K, such as near-infrared or ultraviolet light. The light emitted from the LED 231 (hereinafter sometimes abbreviated as "LED light") passes through the optical window 205, and the light that has passed through the optical window 205 is incident on the wafer K supported by the support pins 220. The light irradiation unit U is configured to irradiate the entire surface of the wafer K supported by the support pins 220 with LED light.

[0052] The load lock device 12 also includes a temperature sensor (not shown) for measuring the temperature of the wafer K supported by the support pins 220.

[0053] The exhaust system 70, gas supply mechanism 210, and heating unit 230 are controlled by the control device 50. In particular, the heating unit 230 is controlled by the control device 50 so that the temperature of the wafer K, measured by the temperature sensor, reaches the set temperature.

[0054] <Film formation process> Next, an example of a film deposition process using the wafer processing system 1 will be explained with reference to Figure 6. Figure 6 is a flowchart illustrating the above example of film deposition process. The following processes are performed under the control of the control device 50.

[0055] (Step S1: Transfer to film deposition apparatus 40) First, wafer K is loaded into the film deposition apparatus 40.

[0056] Specifically, the transport arm 23a of the transport mechanism 23 is inserted into the carrier C to hold one wafer K. The wafer K has an oxide film (e.g., an SiO2 film) on its surface, which serves as the etching layer to be masked by the hard mask formed by the WSi film in this film deposition process. Next, the transport arm 23a is withdrawn from the carrier C, the gate valve G1 is opened, and then the transport arm 23a is inserted from the atmospheric pressure transport device 20 into the housing 200 of the load lock device 12, and the wafer K is transferred from the transport arm 23a to the support pin 220.

[0057] Next, the transport arm 23a is withdrawn from the housing 200 of the load lock device 12, and the gate valve G1 is closed, sealing the inside of the housing 200 of the load lock device 12 and reducing the pressure.

[0058] When it is time to unload the wafer K from the load lock device 12, the gate valve G3 is opened, and the inside of the load lock device 12 and the inside of the vacuum transfer device 30 are connected. Then, the transfer arm 32a of the transfer mechanism 32 is inserted into the housing 200 of the load lock device 12, receives the wafer K from the support pin 220, and holds it. Next, the transfer arm 32a is withdrawn from the housing 200 of the load lock device 12, thereby transferring the wafer K from the load lock device 12 into the vacuum transfer chamber 31.

[0059] Next, after the gate valve G3 is closed, the gate valve G5 for the desired film deposition apparatus 40 is opened. Subsequently, a transport arm 32a holding the wafer K is inserted into the housing 100 of the depressurized desired film deposition apparatus 40, and the wafer K is transported above the mounting table 110. Then, the wafer K is transferred onto a raised support pin (not shown), and after that, the transport arm 32a is withdrawn from the housing 100, and the gate valve G5 is closed. Simultaneously, the support pin is lowered, and the wafer K is placed on the mounting table 110 and held in place by the electrostatic attraction force of the electrostatic chuck 111.

[0060] (Step S2: Film formation) After delivery, an amorphous WSi film is formed on wafer K by the film deposition apparatus 40.

[0061] In this process, an amorphous WSi film is formed on the surface of wafer K, for example, by sputtering. Specifically, Ar gas, for example, is supplied to the housing 100 from the gas supply unit 130 as a sputtering gas. Power is also supplied to each holder 121 from the power supply 122, which in turn supplies power to each target 120, causing the mounting table 110 to rotate and the magnet unit 123 to oscillate. The power ionizes the Ar gas inside the housing 100, and the electrons generated by this ionization drift due to the magnetic field (i.e., leakage magnetic field) formed by the magnet unit 123 in front of the target 120, generating a high-density plasma. The Ar ions generated in this plasma sputter the surface of the target 120, depositing sputtered particles onto the wafer K, forming an amorphous WSi film. After a predetermined time T has elapsed since the start of power supply from the power supply 122, the power supply from the power supply 122, the gas supply from the gas supply unit 130, the rotation of the mounting table 110, and the oscillating of the magnet unit 123 are all stopped.

[0062] The W content of the WSi film formed in this process is 10% to 80%. By reducing the W content to 80% or less, the WSi film can be made amorphous, and by increasing it to 10% or more, the selectivity ratio of the WSi film to the oxide film to be masked can be sufficiently high.

[0063] Furthermore, in this process, the pressure inside the housing 100, i.e., the pressure of the sputtering gas, when the sputtering gas is supplied from the gas supply unit 130, is set to 1 mTorr to 10 mTorr. Specifically, the flow rate of the sputtering gas is adjusted so that the pressure inside the housing 100 is between 1 mTorr and 10 mTorr. By keeping the pressure inside the housing 100 below 1 mTorr, the WSi film can be made amorphous, and the selectivity of the WSi film can be made sufficiently high. Also, by keeping the pressure inside the housing 100 above 1 mTorr, high productivity can be maintained.

[0064] Furthermore, in this embodiment, the wafer K is neither heated nor cooled during this process, and the wafer K is at room temperature.

[0065] The stress within the amorphous WSi film formed under the processing conditions described above, i.e., the film stress of the WSi film, is compressive stress. Furthermore, the thickness of the WSi film formed in step S2 is, for example, 10 to 500 nm.

[0066] (Step S3: Transport to load lock device 12) Next, the wafer K is transported to the load lock device 12, which is a heating device.

[0067] Specifically, in the reverse operation of the transfer from the load lock device 12 to the film deposition device 40 in step S1, the wafer K is transferred from the film deposition device 40 to the load lock device 12 and handed over to the support pin 220.

[0068] (Step S4: Heating) Subsequently, the load lock device 12 heats the wafer K to a temperature at which the amorphous WSi film does not crystallize, and the stress within the amorphous WSi film is changed from compressive stress to tensile stress.

[0069] Specifically, all LEDs 231 of the light irradiation unit U of the heating unit 230 are lit, and the wafer K on the support pins 220 is heated by the LED light. After a predetermined heating time (for example, 10 to 30 minutes) has elapsed from the start of heating, all LEDs 231 are turned off, and the heating of the wafer K by the LED light is terminated.

[0070] During heating, the light irradiation unit U is controlled so that the temperature of the wafer K, as measured by a temperature sensor (not shown), reaches a predetermined set temperature. If the set temperature is too high, the WSi film will crystallize. Conversely, if the set temperature is too low, the film stress of the amorphous WSi film will not change from compressive stress to tensile stress even when the wafer K is heated. Therefore, the set temperature is set, for example, based on prior tests, so that heating at that temperature prevents the amorphous WSi film from crystallizing and changes the film stress of the amorphous WSi film from compressive stress to tensile stress when the wafer K is heated.

[0071] Furthermore, the inventors have conducted extensive testing and found that the temperature at which the amorphous WSi film does not crystallize, and the temperature at which the film stress of the amorphous WSi film changes from compressive stress to tensile stress due to heating of wafer K, differ depending on the W concentration of the WSi film. Therefore, the set temperature of wafer K in this heating process is predetermined according to the W concentration of the WSi film formed in step S2.

[0072] The set temperature of wafer K in step S4 may be higher than the temperature of wafer K during film deposition in step S2. Furthermore, if the film stress of the amorphous WSi film changes from compressive stress to tensile stress, the heat treatment time may be shorter than the time exemplified above.

[0073] (Step S5: Removal) Then, the heated wafer K is transported out of the wafer processing system 1.

[0074] Specifically, in the reverse operation of the transfer from carrier C to load lock device 12 in step S1, wafer K is returned to carrier C. This completes the series of film deposition processes.

[0075] <Evaluation Test> The following describes the tests conducted to evaluate the change in film stress due to heating of the WSi film. In this evaluation test, the above-described film deposition process was performed on multiple wafers K. In this evaluation test, either the W concentration of the amorphous WSi film or the set temperature of wafer K in the heating process of step S4 was varied for each wafer K. Furthermore, for each wafer K, the thickness of the amorphous WSi film formed in step S2 was set to 350 nm, and the heating process time in the heating process of step S4 was set to 30 minutes. In this evaluation test, the stress of the WSi film was measured before and after the heating process of step S4. Figure 7 shows the results of this evaluation test. In Figure 7, the horizontal axis shows the set temperature of wafer K in the heating process of step S4, and the vertical axis shows the film stress. Also, in Figure 7, the data when the set temperature of wafer K in the heating process of step S4 is room temperature (approximately 25°C) refers to the data before the heating process of step S4.

[0076] As shown in the figure, before the heating step S4, the film stress of the amorphous WSi film was compressive stress regardless of the W concentration. In the W concentration range of 60% to 80%, heating the wafer K caused the film stress of the amorphous WSi film to change from compressive stress to tensile stress. However, the temperature at which the stress changed from compressive to tensile stress differed depending on the W concentration of the WSi film. Specifically, the higher the W concentration, the higher the temperature at which the stress changed from compressive to tensile stress.

[0077] Although not shown in the diagram, in the range of W concentration from 60% to 80%, the amorphous WSi film did not crystallize if the set temperature in the heating step S4 was 500°C or lower. Furthermore, the temperature at which the amorphous WSi film did not crystallize due to heating in the heating step S4 also differed depending on the W concentration of the WiS film. Specifically, the higher the W concentration, the higher the temperature at which crystallization did not occur.

[0078] Here, we will explain why the film stress of the amorphous WSi film changes from compressive stress to tensile stress due to the heating of wafer K in step S4. During the heating process in step S4, both wafer K and the amorphous WSi film undergo thermal expansion. However, since the thermal expansion coefficient of W in the amorphous WSi film is greater than that of Si in wafer K, if the heating temperature is sufficiently high, the film stress of the amorphous WSi film changes to tensile stress. When heating is completed, the temperatures of both wafer K and the amorphous WSi film decrease, and both wafer K and the amorphous WSi film undergo thermal contraction. At this time, although the thermal contraction coefficient of W in the amorphous WSi film is higher than that of Si in wafer K, the amorphous WSi film is viscous, so even when the amorphous WSi film is cooled to, for example, room temperature, its film stress remains tensile stress. This is considered to be the reason.

[0079] <Main effects of this embodiment> As described above, the film deposition method according to this embodiment includes a film deposition step S2 in which an amorphous WSi film is formed on a wafer K, and a heating step S4 in which the wafer K is heated at a temperature at which the amorphous WSi film does not crystallize. The heating step allows the film stress of the amorphous WSi film on the wafer K to be converted to tensile stress. Therefore, according to this embodiment, an amorphous WSi film having tensile stress can be formed.

[0080] Furthermore, in this embodiment, the pressure inside the housing 100 during the film formation process in step S2 is the pressure at which the WSi film formed in step S2 becomes amorphous (specifically, 1 mTorr or less). This pressure is the pressure at which the WSi film formed in step S2 becomes high density. In other words, according to this embodiment, a high-density WSi film with a high selectivity can be formed. Furthermore, the heating process in step S4 does not impair the density, or compactness, of the WSi film.

[0081] Furthermore, in this embodiment, by setting the wafer K setting temperature in the heating step S4 according to the W concentration of the WSi film formed in step S2, it is possible to form an amorphous WSi film with tensile stress regardless of the W concentration of the WSi film formed in step S2.

[0082] <Variation> In the above example, both targets 120 contained both W and Si, but if an amorphous WSi film can be formed, one of the targets 120 may contain only W and the other may contain only Si.

[0083] Furthermore, in the above example, the film deposition apparatus 40 and the heating devices configured as load lock devices 12 and 13 were integrated via a vacuum transfer device 30. However, in the technology of this disclosure, the film deposition apparatus 40 and the heating devices may be separate. If they are separate, the wafer K that has undergone film deposition in the film deposition apparatus 40 may be transported under atmospheric pressure and loaded into the heating device.

[0084] Furthermore, in the above example, the set temperature of wafer K in the heating step S4 was predetermined according to the W concentration of the WSi film formed in step S2. Alternatively, the set temperature of wafer K in the heating step S4 may be set to a temperature (for example, 400°C) that allows the film stress of the amorphous WSi film to be changed from compressive stress to tensile stress without crystallizing the amorphous WSi film by heating, regardless of the W concentration of the WSi film formed in step S2.

[0085] Furthermore, while LEDs were used as the heating light source in the above example, other light sources may be used for heating. Also, the method of heating wafer K is not limited to light. For example, wafer K may be heated by heating the stage on which it is placed.

[0086] In the above example, the WSi film was formed by sputtering, but other film deposition methods (e.g., CVD) may also be used to form the WSi film.

[0087] Furthermore, although a WSi film was formed in the above example, the technology of this disclosure can be applied to alloy films containing W other than WSi films. For example, the technology of this disclosure can be applied to tungsten nitride silicide (WSiN) films, tungsten boride silicide (WSiB) films, tungsten carbide (WC) films, tungsten nitride carbide (WCN) films, tungsten boride (WCB) films, and the like.

[0088] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The above embodiments may be omitted, replaced, or modified in various ways without departing from the scope and spirit of the appended claims. [Explanation of Symbols]

[0089] 1. Wafer Processing System 12 Load lock device 13 Load lock device 40 Film deposition equipment 50 Control device K wafer

Claims

1. A first step involves forming an amorphous tungsten silicide film with a tungsten concentration of 60-80% on a substrate with a lower coefficient of thermal expansion than the tungsten silicide film, without heating or cooling. A film formation method comprising: a second step of subsequently heating the substrate at a temperature at which the tungsten silicide film does not crystallize to form the tungsten silicide film having tensile stress.

2. The first step is to form the tungsten silicide film by sputtering, as described in claim 1.

3. The film formation method according to claim 2, wherein in the first step, the pressure inside the processing container housing the substrate is 1 mTorr to 10 mTorr.

4. The film formation method according to any one of claims 1 to 3, wherein the temperature at which crystallization does not occur is set in advance according to the tungsten concentration of the tungsten silicide film formed in the first step.

5. The first step is to form the tungsten silicide film having compressive stress within the film, The second step is to change the stress in the tungsten silicide film from compressive stress to tensile stress by heating, as described in any one of claims 1 to 4.

6. The film formation method according to claim 5, wherein the heating temperature in the second step is higher than the temperature of the substrate in the first step.

7. A film deposition apparatus, Heating device, A control device is provided, The control device is The first step involves forming an amorphous tungsten silicide film with a tungsten concentration of 60-80% on a substrate with a lower coefficient of thermal expansion than the tungsten silicide film, without heating or cooling, using the aforementioned film deposition apparatus. A film deposition system that controls the system to subsequently perform a second step of heating the substrate with the heating device at a temperature at which the tungsten silicide film does not crystallize, thereby forming the tungsten silicide film having tensile stress.

8. The film deposition system according to claim 7, wherein the first step is to form the tungsten silicide film by sputtering using the film deposition apparatus.

9. The film deposition apparatus has a processing container for housing the substrate, The film deposition system according to claim 8, wherein in the first step, the pressure inside the processing vessel is 1 mTorr to 10 mTorr.

10. The film formation system according to any one of claims 7 to 9, wherein the temperature at which crystallization does not occur is set in advance according to the tungsten concentration of the tungsten silicide film formed in the first step.

11. The first step is to form the tungsten silicide film having compressive stress within the film, The film deposition system according to any one of claims 7 to 10, wherein the second step involves heating to change the stress in the tungsten silicide film from compressive stress to tensile stress.

12. The film deposition system according to claim 11, wherein the heating temperature in the second step is higher than the temperature of the substrate in the first step.

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