JP2012169590A - FORMATION METHOD OF Cu WIRING, DEPOSITION METHOD OF Cu FILM, AND DEPOSITION SYSTEM - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure to bury Cu in a recessed part such as a fine trench or a hole without causing voids and form Cu wiring having low resistance.SOLUTION: A formation method of Cu wiring has: a process where a barrier film 204 is formed on a surface of a trench 203 in an interlayer insulation film 202 having the trench 203 formed on a wafer W; a process where an Ru film 205 is formed on the barrier film 204; and a process where a Cu film 206 is formed on the Ru film 205 through physical vapor deposition with the wafer heated so that Cu migrates and the trench 203 is buried.

Description

  The present invention relates to a Cu wiring forming method for forming a Cu wiring in a trench or hole formed in a substrate, a Cu film forming method, and a film forming system for forming a Cu wiring.

  In the manufacture of semiconductor devices, various processes such as film formation and etching are repeatedly performed on a semiconductor wafer to manufacture a desired device. Recently, however, the speed of semiconductor devices, the miniaturization of wiring patterns, and the high integration Corresponding to the demands for making them, there is a demand for improving the electrical conductivity of the wiring and the electromigration resistance.

  Corresponding to these points, copper (Cu) having higher conductivity (lower resistance) and better electromigration resistance than aluminum (Al) and tungsten (W) is used as the wiring material. It is coming.

  As a method of forming Cu wiring, a barrier film made of tantalum metal (Ta), titanium (Ti), tantalum nitride film (TaN), titanium nitride film (TiN), etc. is formed on the entire interlayer insulating film in which trenches and holes are formed. It is formed by PVD plasma sputtering, and a Cu seed film is also formed on the barrier film by plasma sputtering. Further, Cu plating is applied on the barrier film to completely fill trenches and holes, and an extra copper thin film on the wafer surface is formed. There has been proposed a technique of removing by polishing by CMP (Chemical Mechanical Polishing) (for example, Patent Document 1). In addition, as a technique capable of forming a Cu film with good adhesion and a fine pattern, there is also a method of forming a Cu seed film and Cu plating after forming a Ru film on the barrier film by CVD (Chemical Vapor Deposition). It has been proposed (for example, Patent Document 2).

JP 2006-148075 A JP 2007-194624 A

  However, semiconductor device design rules are becoming increasingly finer, trench widths and hole diameters are several tens of nanometers, and barrier films and seed films are formed by plasma sputtering in such narrow trenches and holes. In the case of forming, an overhang portion is generated in the opening portion of the trench or hole, and even if the trench or hole is buried by subsequent Cu plating, the inside is not sufficiently filled and a void is generated. .

  In the above-mentioned Patent Document 1, an attempt is made to perform satisfactory filling by adjusting the bias power supplied to the mounting table of the plasma sputtering apparatus to control the film formation rate and the etching rate of sputter etching. Improvement of Cu plating embeddability has also been studied, and Cu embeddability is also improved in Patent Document 2 described above, but recently it is possible to cope with further miniaturized trenches and holes. Have difficulty.

  In addition, Cu plating has many impurities, and the current situation is that it cannot always respond sufficiently to the demand for lower resistance of wiring.

  The present invention has been made in view of such circumstances, and can reliably embed Cu without generating voids in concave portions such as fine trenches or holes, and form a low-resistance Cu wiring. It is an object of the present invention to provide a method for forming a Cu wiring, a method for forming a Cu film, and a film forming system for forming such a Cu wiring.

  According to a first aspect of the present invention, there is provided a Cu wiring forming method for forming a Cu wiring by embedding Cu in a recess formed in a substrate, the method comprising forming a barrier film at least on the surface of the recess, Forming a Ru film on the barrier film; and forming a Cu film on the Ru film so that Cu migrates by PVD while being heated, and embedding Cu in the recess. A method for forming a Cu wiring is provided. In this case, the recess may include a trench or a hole.

  According to a second aspect of the present invention, there is provided a Cu wiring forming method for forming a Cu wiring by embedding Cu in a recess formed in a substrate, wherein a step of forming a barrier film at least on the surface of the recess, Forming a Ru film on the barrier film, and forming a Cu film on the Ru film so that Cu migrates by PVD while heating, and embedding Cu in the recess. The recess has a trench and a hole formed at the bottom of the trench, and the step of forming the Cu film and embedding Cu in the recess is performed until the Cu is completely embedded in the hole. A first stage and a second stage from the completion of the hole filling to the completion of the trench filling, wherein the first stage deposition rate is lower than the second stage deposition rate. With features It provides a method of forming that Cu wiring.

  In the second aspect, it is preferable that the film formation rate in the first stage is a film formation rate that ensures the fluidity of Cu to such an extent that no overhang occurs at the bottom of the trench. The first stage film formation rate is preferably 5 to 20 nm / min, and the second stage film formation speed is preferably 20 to 150 nm / min.

  In the first aspect and the second aspect, the Cu film for embedding Cu generates plasma with a plasma generation gas in a processing container in which a substrate is accommodated, and releases Cu from a Cu target to form Cu. Is preferably ionized in the plasma, and a bias power is applied to the substrate to attract Cu ions onto the substrate.

  In this case, the formation of the Cu film for embedding Cu is preferably performed at a substrate temperature of 65 ° C. or higher and 350 ° C. or lower.

The formation of the Cu film for embedding Cu in the substrate temperature was set to 200 ° C. Ultra 350 ° C. or less, and the amount of etching ions by Cu film of the Cu deposition amount T _D and the plasma generation gas to the substrate by the Cu ions T _E can be performed by adjusting the magnitude of the bias power so as to satisfy the relation of _{0 ≦ T E / T D <} 1. The formation of the Cu film, the substrate temperature was below 200 ° C. 65 ° C. or higher, and the Cu deposition amount T _D and the etching amount T _E of ions by Cu film of the plasma generation gas of Cu ions to the substrate 0. The bias power can be adjusted so as to satisfy the relationship of 02 ≦ T _E / T _D <1. In these cases, the magnitude of the bias power is preferably adjusted so as to satisfy 0.05 ≦ T _E / T _D ≦ 0.24.

  In the first and second aspects, the barrier film includes a Ti film, a TiN film, a Ta film, a TaN film, a Ta / TaN two-layer film, a TaCN film, a W film, a WN film, a WCN film, and a Zr film. A film selected from the group consisting of a film, a ZrN film, a V film, a VN film, an Nb film, and an NbN film can be used. The barrier film is preferably formed by PVD.

  The Ru film is preferably formed by CVD. The Ru film is more preferably formed by CVD using ruthenium carbonyl as a film forming material.

  In a third aspect of the present invention, a Cu film forming method for forming a Cu film for embedding Cu in a recess through a barrier film and a Ru film in a predetermined layer having a recess formed in a substrate A Cu film forming method is provided, in which a Cu film is formed so that Cu migrates by PVD while being heated on the Ru film, and Cu is embedded in the recess. To do.

  In a fourth aspect of the present invention, a Cu film forming method for forming a Cu film for embedding Cu in a recess formed in a predetermined layer having a recess formed in a substrate via a barrier film and an Ru film The concave portion has a trench and a hole formed at the bottom of the trench, and while heating on the Ru film, forming a Cu film so that Cu migrates by PVD, Cu is embedded in the recess, and the formation of the Cu film is a first stage until the filling of the Cu into the hole is completed, and after the filling of the hole is completed, the filling of the trench is completed. A Cu film forming method, wherein the film forming speed of the first stage is smaller than the film forming speed of the second stage.

  According to a fifth aspect of the present invention, there is provided a film forming system for forming a Cu wiring by embedding Cu in a concave portion formed on a substrate, wherein the barrier film forming apparatus forms a barrier film on the surface of the concave portion. A Ru film forming apparatus that forms a Ru film on the barrier film, a Cu film forming apparatus that forms a Cu film on the Ru film by PVD and embeds Cu in the recess, and the Cu film A film forming system comprising: a control unit configured to control a film forming apparatus so that Cu is migrated and Cu is embedded in the recess while heating the substrate. To do.

  In the film forming system, it is preferable that the film forming system further includes a transport unit that transports the barrier film forming apparatus, the Ru film forming apparatus, and the Cu film forming apparatus without breaking a vacuum.

  According to a sixth aspect of the present invention, there is provided a storage medium that operates on a computer and stores a program for controlling the film forming system, and the program is executed when the program is executed according to the first or second aspect. Provided is a storage medium characterized by causing a computer to control the film forming system so that a Cu wiring forming method is performed.

  According to a seventh aspect of the present invention, there is provided a storage medium that operates on a computer and stores a program for controlling a film forming apparatus, wherein the program is executed according to the third or fourth aspect when executed. Provided is a storage medium characterized by causing a computer to control the film forming apparatus so that a Cu film forming method is performed.

  According to the present invention, when Cu is formed by embedding Cu in a recess such as a trench or a hole formed in a substrate, a Ru film is formed on the barrier film, and a Cu film is formed thereon by PVD. Then, Cu is embedded in the recess, but Cu has good wettability to Ru, so that migration can be performed without aggregating Cu on the Ru film. For this reason, by forming the Cu film so that Cu migrates while heating, Cu does not flow into the recess and does not block the opening of the recess, so that a fine trench or hole is formed as the recess. Even in this case, Cu can be reliably filled without generating voids therein. Further, since the Cu wiring is formed only by PVD, it is possible to realize a low resistance Cu wiring with less impurities.

  In addition, when the structure of the recess has a trench and a hole formed at the bottom of the trench, even if a Cu film is formed so that Cu migrates, an overhang occurs at the bottom of the trench and the hole portion In the first step until the Cu filling into the hole is completed, and after the hole filling is completed, The formation of such voids is prevented by having a second stage until the trench filling is completed and by making the first stage deposition rate smaller than the second stage deposition rate. be able to.

It is a top view which shows an example of the multi-chamber type film-forming system for enforcing the formation method of Cu wiring concerning the present invention. It is sectional drawing which shows Cu film | membrane film-forming apparatus for forming Cu film | membrane mounted in the film-forming system of FIG. It is sectional drawing which shows the Ru liner film | membrane film-forming apparatus for forming the Ru liner film | membrane mounted in the film-forming system of FIG. It is a flowchart of the formation method of Cu wiring which concerns on the 1st Embodiment of this invention. It is process sectional drawing for demonstrating the formation method of Cu wiring which concerns on the 1st Embodiment of this invention. It is a schematic diagram which shows the relationship between the bias power and Cu film-forming amount in the case of forming Cu film | membrane with the apparatus of FIG. It is a schematic diagram for demonstrating the film-forming model in the case of forming Cu film | membrane with the apparatus of FIG. When the Cu film is actually formed with the apparatus of FIG. 2, the horizontal axis represents the DC power supplied to the Cu target, the vertical axis represents the bias power, and the values of T _E / T _D are shown by contour lines. is there. When the Cu film is actually formed with the apparatus of FIG. 2, the horizontal axis represents the bias power, the vertical axis represents T _E / T _D, and the graph shows these relationships for each DC power to the Cu target. is there. Scanning electrons when a Cu film is formed with a bias power of 130 W (0.19 W / cm ² ) at which T _E / T _D = 0 and film formation temperatures of 200 ° C., 225 ° C., 250 ° C., and 300 ° C. It is a microscope (SEM) photograph. As 130W comprising a bias power and _{T E / T D = 0 (} 0.19W / cm 2), and _T E _{/ T} D = 0.02 and made 195W (0.28W / cm ^2), film formation temperature 65 ° C. It is a scanning electron microscope (SEM) photograph at the time of forming a Cu film | membrane by (1). Scanning electron microscope (SEM) photograph when changing the bias power so that T _E / T _D becomes 0 to 0.24 and forming a Cu film at a film formation temperature of 250 ° C. for a film formation time of 56 sec. is there. Scanning of a state in which only a Ti barrier film is formed, a state in which a Ru liner film is formed, and a state in which a Cu film is formed to 5 nm, 10 nm, 20 nm, and 30 nm when Cu wiring is formed according to the first embodiment of the present invention It is a scanning electron microscope (SEM) photograph. It is a figure which shows the result of having compared the electrical characteristic of Cu wiring formed by the 1st Embodiment of this invention, and the conventional Cu wiring using Cu plating. It is a flowchart of the formation method of Cu wiring concerning a 2nd embodiment of the present invention. It is process sectional drawing for demonstrating the formation method of Cu wiring which concerns on the 2nd Embodiment of this invention. It is a figure for demonstrating the mechanism in case a void arises in the via | veer formed in the trench bottom part when Cu is embedded to a dual damascene structure. It is a figure for demonstrating the state at the time of embedding Cu in the dual damascene structure according to 2nd Embodiment. In the film-forming apparatus of FIG. 2, it is a figure which shows the relationship between the power of DC power supply, and Cu deposition rate.

  Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings.

<Film Forming System Used in Embodiment of the Present Invention>
FIG. 1 is a plan view showing an example of a multi-chamber type film forming system for carrying out a Cu wiring forming method according to the present invention.

  The film forming system 1 includes a first processing unit 2 that forms a barrier film and a Ru liner film, a second processing unit 3 that forms a Cu film, and a loading / unloading unit 4. Hereinafter, simply referred to as a wafer.) For forming a Cu wiring for W.

  The first processing unit 2 includes a first vacuum transfer chamber 11 having a heptagonal planar shape and two barrier films connected to wall portions corresponding to the four sides of the first vacuum transfer chamber 11. It has film forming apparatuses 12a and 12b and two Ru liner film forming apparatuses 14a and 14b. The barrier film forming apparatus 12a and the Ru liner film forming apparatus 14a, and the barrier film forming apparatus 12b and the Ru liner film forming apparatus 14b are arranged in line-symmetric positions.

  Degas chambers 5 a and 5 b for degassing the wafer W are connected to the walls corresponding to the other two sides of the first vacuum transfer chamber 11. Further, the wafer W is transferred between the first vacuum transfer chamber 11 and a second vacuum transfer chamber 21 described later on the wall portion between the degas chambers 5a and 5b of the first vacuum transfer chamber 11. A delivery chamber 5 is connected.

  The barrier film forming apparatuses 12a and 12b, the Ru liner film forming apparatuses 14a and 14b, the degas chambers 5a and 5b, and the delivery chamber 5 are connected to the respective sides of the first vacuum transfer chamber 11 through gate valves G. These are communicated with the first vacuum transfer chamber 11 by opening the corresponding gate valve G, and are disconnected from the first vacuum transfer chamber 11 by closing the corresponding gate valve G.

  The inside of the first vacuum transfer chamber 11 is maintained in a predetermined vacuum atmosphere, and among these, barrier film forming apparatuses 12a and 12b, Ru liner film forming apparatuses 14a and 14b, and a degas chamber 5a. , 5b, and a first transfer mechanism 16 for carrying the wafer W in and out of the delivery chamber 5. The first transfer mechanism 16 is disposed substantially at the center of the first vacuum transfer chamber 11, and has a rotation / extension / contraction part 17 that can be rotated and expanded / contracted. Two support arms 18a and 18b for supporting W are provided, and these two support arms 18a and 18b are attached to the rotating / extending / contracting portion 17 so as to face opposite directions.

  The second processing unit 3 includes a second vacuum transfer chamber 21 having a heptagonal planar shape, and two wall portions connected to two opposing sides of the second vacuum transfer chamber 21. Cu film forming apparatuses 22a and 22b.

  The degas chambers 5a and 5b are connected to the wall portions corresponding to the two sides of the second vacuum transfer chamber 21 on the first processing unit 2 side, respectively, and the wall portion between the degas chambers 5a and 5b is connected to the walls. The delivery chamber 5 is connected. That is, the delivery chamber 5 and the degas chambers 5 a and 5 b are both provided between the first vacuum transfer chamber 11 and the second vacuum transfer chamber 21, and the degas chambers 5 a and 5 b are arranged on both sides of the transfer chamber 5. Has been. Furthermore, load lock chambers 6a and 6b capable of atmospheric conveyance and vacuum conveyance are connected to the two sides on the carry-in / out section 4 side, respectively.

  The Cu film forming apparatuses 22a and 22b, the degas chambers 5a and 5b, and the load lock chambers 6a and 6b are connected to the respective sides of the second vacuum transfer chamber 21 through gate valves G, which correspond to the corresponding gate valves. Is opened and communicated with the second vacuum transfer chamber 21, and is closed from the second vacuum transfer chamber 21 by closing the corresponding gate valve G. The delivery chamber 5 is connected to the second vacuum transfer chamber 21 without a gate valve.

  The inside of the second vacuum transfer chamber 21 is maintained in a predetermined vacuum atmosphere. Among them, Cu film forming apparatuses 22a and 22b, degas chambers 5a and 5b, load lock chambers 6a and 6b, In addition, a second transfer mechanism 26 for carrying the wafer W in and out of the delivery chamber 5 is provided. The second transfer mechanism 26 is disposed substantially at the center of the second vacuum transfer chamber 21, and has a rotation / extension / contraction part 27 that can be rotated and expanded / contracted. Two support arms 28a and 28b for supporting W are provided, and these two support arms 28a and 28b are attached to the rotating / extending / contracting portion 27 so as to face opposite directions.

  The loading / unloading unit 4 is provided on the opposite side of the second processing unit 3 with the load lock chambers 6a and 6b interposed therebetween, and has an atmospheric transfer chamber 31 to which the load lock chambers 6a and 6b are connected. . A gate valve G is provided on a wall portion between the load lock chambers 6 a and 6 b and the atmospheric transfer chamber 31. Two connection ports 32 and 33 for connecting a carrier C that accommodates a wafer W as a substrate to be processed are provided on the wall portion of the atmospheric transfer chamber 31 that faces the wall portion to which the load lock chambers 6a and 6b are connected. Yes. Each of the connection ports 32 and 33 is provided with a shutter (not shown). A wafer C containing a wafer W or an empty carrier C is directly attached to the connection ports 32 and 33, and the shutter is released at that time. The air communication chamber 31 communicates with the outside air while preventing the outside air from entering. An alignment chamber 34 is provided on the side surface of the atmospheric transfer chamber 31 where the wafer W is aligned. In the atmospheric transfer chamber 31, an atmospheric transfer transfer mechanism 36 that loads and unloads the wafer W with respect to the carrier C and loads and unloads the wafer W with respect to the load lock chambers 6 a and 6 b is provided. This atmospheric transfer mechanism 36 has two articulated arms, and can run on the rail 38 along the arrangement direction of the carrier C. The wafer W is placed on the hand 37 at each tip. It is loaded and transported.

  The film forming system 1 has a control unit 40 for controlling each component of the film forming system 1. The control unit 40 includes a process controller 41 composed of a microprocessor (computer) that executes control of each component, a keyboard on which an operator inputs commands to manage the film forming system 1, and a film forming system. 1, a user interface 42 including a display for visualizing and displaying the operation status of 1, a control program for realizing processing executed by the film forming system 1 under the control of the process controller 41, various data, and processing conditions And a storage unit 43 that stores a program for causing each component of the processing apparatus to execute processing, that is, a recipe. Note that the user interface 42 and the storage unit 43 are connected to the process controller 41.

  The recipe is stored in the storage medium 43 a in the storage unit 43. The storage medium may be a hard disk or a portable medium such as a CDROM, DVD, or flash memory. Moreover, you may make it transmit a recipe suitably from another apparatus via a dedicated line, for example.

  Then, if desired, an arbitrary recipe is called from the storage unit 43 by an instruction from the user interface 42 and is executed by the process controller 41, so that a desired value in the film forming system 1 is controlled under the control of the process controller 41. Is performed.

  In such a film forming system 1, the wafer W on which a predetermined pattern having trenches and holes is formed is taken out from the carrier C by the atmospheric transfer mechanism 36 and transferred to the load lock chamber 6a or 6b. Is depressurized to the same degree of vacuum as the second vacuum transfer chamber 21, the wafer W in the load lock chamber is taken out by the second transfer mechanism 26, and the degas chamber 5 a or 5 b is removed via the second vacuum transfer chamber 21. The wafer W is degassed. After that, the wafer W in the degas chamber is taken out by the first transfer mechanism 16 and loaded into the barrier film forming apparatus 12a or 12b through the first vacuum transfer chamber 11, and for example, a Ti film, a TiN film, A Ta film, a TaN film, or the like is formed. After the barrier film is formed, the wafer W is taken out from the barrier film forming apparatus 12a or 12b by the first transport mechanism 16 and loaded into the Ru liner film forming apparatus 14a or 14b, and a Ru liner film is formed. After forming the Ru liner film, the wafer W is taken out from the Ru liner film forming apparatus 14 a or 14 b by the first transfer mechanism 16 and transferred to the delivery chamber 5. Thereafter, the wafer W is taken out by the second transfer mechanism 26 and transferred into the Cu film forming apparatus 22a or 22b via the second vacuum transfer chamber 21, and a Cu film is formed. After the Cu film is formed, the wafer W is taken out from the Cu film forming apparatus 22a or 22b by the second transfer mechanism 26, transferred to the load lock chamber 6a or 6b, and the load lock chamber is returned to the atmospheric pressure. The wafer W on which the Cu film is formed is taken out by the transfer mechanism 36 and transferred back to the carrier C. Such a process is repeated for the number of wafers W in the carrier.

<Cu film deposition system>
Next, the Cu film forming apparatus 22a (22b) important for carrying out the method of the present invention will be described.
FIG. 2 is a cross-sectional view showing an example of a Cu film forming apparatus. Here, an ICP (Inductively Coupled Plasma) type plasma sputtering apparatus which is an iPVD (Ionized physical vapor deposition) will be described as an example of the Cu film forming apparatus.

As shown in FIG. 2, the Cu film forming apparatus 22a (22b) includes a processing container 51 formed into a cylindrical shape with, for example, aluminum. The processing vessel 51 is grounded, and an exhaust port 53 is provided at the bottom 52, and an exhaust pipe 54 is connected to the exhaust port 53. A throttle valve 55 and a vacuum pump 56 for adjusting pressure are connected to the exhaust pipe 54 so that the inside of the processing container 51 can be evacuated. Further, a gas inlet 57 for introducing a predetermined gas into the processing container 51 is provided at the bottom 52 of the processing container 51. A gas supply pipe 58 is connected to the gas inlet 57 for supplying a rare gas such as Ar gas or other necessary gas such as N ₂ gas as the plasma excitation gas. The gas supply source 59 is connected. The gas supply pipe 58 is provided with a gas control unit 60 including a gas flow rate controller and a valve.

  In the processing container 51, a mounting mechanism 62 for mounting a wafer W as a substrate to be processed is provided. The mounting mechanism 62 includes a mounting table 63 formed in a disc shape, and a hollow cylindrical column support 64 that supports the mounting table 63 and is grounded. The mounting table 63 is made of a conductive material such as an aluminum alloy, and is grounded via a support column 64. A cooling jacket 65 is provided in the mounting table 63 so as to supply the refrigerant through a refrigerant channel (not shown). A resistance heater 87 covered with an insulating material is embedded on the cooling jacket 65 in the mounting table 63. The resistance heater 87 is supplied with power from a power source (not shown). The mounting table 63 is provided with a thermocouple (not shown), and by controlling the supply of the refrigerant to the cooling jacket 65 and the power supply to the resistance heater 87 based on the temperature detected by the thermocouple. The wafer temperature can be controlled to a predetermined temperature.

  On the upper surface side of the mounting table 63, for example, a thin disk-shaped electrostatic chuck 66 configured by embedding an electrode 66b in a dielectric member 66a such as alumina is provided. It can be held by suction. Further, the lower portion of the support column 64 extends downward through an insertion hole 67 formed at the center of the bottom 52 of the processing vessel 51. The support column 64 can be moved up and down by an elevator mechanism (not shown), whereby the entire mounting mechanism 62 is moved up and down.

  A bellows-like metal bellows 68 configured to be stretchable is provided so as to surround the support column 64, and the upper end of the metal bellows 68 is airtightly joined to the lower surface of the mounting table 63, and the lower end thereof is a processing container. It is airtightly joined to the upper surface of the bottom part 52 of 51, and the raising / lowering movement of the mounting mechanism 62 can be permitted while maintaining the airtightness in the processing container 51.

  Further, for example, three support pins 69 (only two are shown in FIG. 2) are provided upright on the bottom portion 52, and are provided on the mounting table 63 so as to correspond to the support pins 69. An insertion hole 70 is formed. Therefore, when the mounting table 63 is lowered, the wafer W is received by the upper end portion of the support pin 69 penetrating the pin insertion hole 70, and between the transfer arm (not shown) that enters the wafer W from the outside. Can be transferred. For this reason, a carry-out / inlet 71 is provided in the lower side wall of the processing container 51 in order to allow the transfer arm to enter, and the carry-out / inlet 71 is provided with a gate valve G that can be opened and closed. On the opposite side of the gate valve G, the aforementioned second vacuum transfer chamber 21 is provided.

  In addition, a chuck power source 73 is connected to the electrode 66b of the electrostatic chuck 66 through a power supply line 72. By applying a DC voltage to the electrode 66b from the chuck power source 73, the wafer W is brought into a static state. Adsorbed and held by electric power. A bias high frequency power source 74 is connected to the power supply line 72, and bias high frequency power is supplied to the electrode 66 b of the electrostatic chuck 66 via the power supply line 72, and bias power is applied to the wafer W. It has come to be. The frequency of the high frequency power is preferably 400 kHz to 60 MHz, and for example, 13.56 MHz is adopted.

  On the other hand, a transmission plate 76 that is permeable to high frequencies made of a dielectric material such as alumina, for example, is hermetically provided on the ceiling of the processing vessel 51 via a seal member 77 such as an O-ring. A plasma generation source 78 for generating a plasma by generating a rare gas, for example, Ar gas, as a plasma excitation gas in the processing space S in the processing vessel 51 in the upper portion of the transmission plate 76 is provided. As this plasma excitation gas, other rare gases such as He, Ne, Kr, etc. may be used instead of Ar.

  The plasma generation source 78 has an induction coil 80 provided so as to correspond to the transmission plate 76. To this induction coil 80, for example, a 13.56 MHz high frequency power source 81 for plasma generation is connected, and the transmission is performed. High frequency power is introduced into the processing space S via the plate 76 to form an induced electric field.

  A baffle plate 82 made of aluminum, for example, is provided directly below the transmission plate 76 to diffuse the introduced high-frequency power. Further, at the lower part of the baffle plate 82, for example, an annular (a frustoconical shell-shaped) Cu target 83 is provided so as to surround the upper side of the processing space S and the cross section is inclined inward. The Cu target 83 is connected to a target variable voltage DC power supply 84 for applying DC power for attracting Ar ions. An AC power supply may be used instead of the DC power supply.

  A magnet 85 is provided on the outer peripheral side of the Cu target 83 to apply a magnetic field thereto. The Cu target 83 is sputtered as Cu metal atoms or metal atomic groups by Ar ions in the plasma, and is mostly ionized when passing through the plasma.

  A cylindrical protective cover member 86 made of, for example, aluminum or copper is provided below the Cu target 83 so as to surround the processing space S. The protective cover member 86 is grounded, and a lower portion thereof is bent inward and is positioned in the vicinity of the side portion of the mounting table 63. Therefore, the inner end of the protective cover member 86 is provided so as to surround the outer peripheral side of the mounting table 63.

  Each component of the Cu film forming apparatus is also controlled by the control unit 40 described above.

  In the Cu film forming apparatus configured as described above, the wafer W is loaded into the processing container 51 shown in FIG. 2, and the wafer W is placed on the mounting table 63 and adsorbed by the electrostatic chuck 66. The following operations are performed under the control of the control unit 40. At this time, the mounting table 63 is heated to a predetermined temperature by the resistance heater 87 and temperature controlled.

  First, by operating the gas control unit 60 and flowing the Ar gas at a predetermined flow rate into the processing container 51 that is brought into a predetermined vacuum state by operating the vacuum pump 56, the throttle valve 55 is controlled to control the inside of the processing container 51. Is maintained at a predetermined degree of vacuum. Thereafter, a DC voltage is applied from the variable DC power source 84 to the Cu target 83, and high frequency power (plasma power) is supplied from the high frequency power source 81 of the plasma generation source 78 to the induction coil 80. On the other hand, a predetermined high frequency power for bias is supplied from the high frequency power source 74 for bias to the electrode 66 b of the electrostatic chuck 66.

  Thereby, in the processing container 51, argon plasma is formed by the high frequency power supplied to the induction coil 80 to generate argon ions, and these ions are attracted to the DC voltage applied to the Cu target 83 to be Cu target. The Cu target 83 is sputtered and Cu particles are released. At this time, the amount of Cu particles released is optimally controlled by a DC voltage applied to the Cu target 83.

  Further, Cu atoms and Cu atomic groups, which are Cu particles from the sputtered Cu target 83, are mostly ionized when passing through the plasma. Here, the Cu particles are scattered in a downward direction in a state where ionized Cu ions and electrically neutral Cu atoms are mixed. In particular, the pressure in the processing vessel 51 is increased to some extent, thereby increasing the plasma density so that the Cu particles can be ionized with high efficiency. The ionization rate at this time is controlled by the high frequency power supplied from the high frequency power supply 81.

  Then, when Cu ions enter the region of an ion sheath having a thickness of about several millimeters formed on the wafer W surface by the high frequency power for bias applied to the electrode 66b of the electrostatic chuck 66 from the high frequency power source 74 for bias. The Cu thin film is formed by being attracted so as to accelerate toward the wafer W with strong directivity and deposited on the wafer W. At this time, by adjusting the bias power applied to the electrode 66b of the electrostatic chuck 66 from the high frequency power source 74 for bias, the film formation by Cu and the etching by Ar are adjusted to realize an appropriate film formation. Can do. Details of this point will be described later.

<Barrier film deposition system>
The barrier film forming apparatus 12a (12b) can be formed by plasma sputtering using a film forming apparatus having the same configuration as the film forming apparatus shown in FIG. Further, the present invention is not limited to plasma sputtering, but may be other PVD such as normal sputtering, ion plating, CVD (Chemical Vapor Deposition), ALD (Atomic Layer Deposition), or CVD or ALD using plasma. A membrane can also be formed. From the viewpoint of reducing impurities, PVD is preferred.

<Ru film deposition system>
Next, the Ru liner film forming apparatus 14a (14b) for forming the Ru liner film will be described. The Ru liner film can be suitably formed by thermal CVD. FIG. 3 is a cross-sectional view showing an example of a Ru film forming apparatus, in which a Ru film is formed by thermal CVD.

  As shown in FIG. 3, this Ru liner film forming apparatus 14a (14b) has a processing vessel 101 formed in a cylindrical body of, for example, aluminum. Inside the processing vessel 101, a mounting table 102 made of ceramics such as AlN for mounting the wafer W is disposed, and a heater 103 is provided in the mounting table 102. The heater 103 generates heat when supplied with power from a heater power source (not shown).

On the top wall of the processing vessel 101, a shower head 104 for introducing a processing gas for forming a Ru film, a purge gas or the like into the processing vessel 101 in a shower shape is provided so as to face the mounting table 102. . The shower head 104 has a gas introduction port 105 in the upper portion thereof, a gas diffusion space 106 is formed in the interior thereof, and a number of gas discharge holes 107 are formed in the bottom surface thereof. A gas supply pipe 108 is connected to the gas inlet 105, and a gas supply source 109 for supplying a processing gas, a purge gas, and the like for forming a Ru film is connected to the gas supply pipe 108. The gas supply pipe 108 is provided with a gas control unit 110 including a gas flow rate controller and a valve. Examples of the gas for forming the Ru film include ruthenium carbonyl (Ru ₃ (CO) ₁₂ ). This ruthenium carbonyl becomes Ru by thermal decomposition, and a Ru film can be formed on the wafer W.

  An exhaust port 111 is provided at the bottom of the processing container 101, and an exhaust pipe 112 is connected to the exhaust port 111. A throttle valve 113 and a vacuum pump 114 for adjusting pressure are connected to the exhaust pipe 112, and the inside of the processing vessel 101 can be evacuated.

  On the mounting table 102, three wafer support pins 116 for wafer transfer (only two are shown) are provided so as to be able to project and retract with respect to the surface of the mounting table 102, and these wafer support pins 116 are fixed to the support plate 117. Has been. The wafer support pins 116 are moved up and down via the support plate 117 by moving the rod 119 up and down by a drive mechanism 118 such as an air cylinder. Reference numeral 120 denotes a bellows. On the other hand, a wafer loading / unloading port 121 is formed on the side wall of the processing chamber 101, and the wafer W is loaded into and unloaded from the first vacuum transfer chamber 11 with the gate valve G opened.

In such a Ru liner film forming apparatus 14 a (14 b), the gate valve G is opened, the wafer W is placed on the mounting table 102, the gate valve G is closed, and the inside of the processing chamber 101 is vacuum pumped 114. While the wafer W is heated to a predetermined temperature from the heater 103 via the mounting table 102 while the inside of the processing vessel 101 is adjusted to a predetermined pressure by evacuating the gas from the gas supply source 109 to the gas supply pipe 108 and the shower head 104. A processing gas such as ruthenium carbonyl (Ru ₃ (CO) ₁₂ ) gas is introduced into the processing vessel 101 through As a result, the reaction of the processing gas proceeds on the wafer W, and a Ru film is formed on the surface of the wafer W.

For the formation of the Ru film, other film forming materials other than ruthenium carbonyl, for example, (cyclopentadienyl) (2,4-dimethylpentadienyl) ruthenium, bis (cyclopentadienyl) (2,4-methyl) Pentadienyl of ruthenium such as pentadienyl) ruthenium, (2,4-dimethylpentadienyl) (ethylcyclopentadienyl) ruthenium, bis (2,4-methylpentadienyl) (ethylcyclopentadienyl) ruthenium The compound can be used with a cracked gas such as O ₂ gas. In addition, the Ru film can be formed by PVD. However, it is preferable to form a film by CVD using ruthenium carbonyl because good step coverage can be obtained and impurities in the film can be reduced.

<Method for Forming Cu Wiring According to First Embodiment>
Next, a Cu wiring forming method according to the first embodiment of the present invention will be described with reference to the flowchart of FIG. 4 and the process cross-sectional view of FIG.

In this embodiment, first, a wafer W having an interlayer insulating film 202 such as a SiO ₂ film on a lower structure 201 (details omitted) and having a trench 203 formed as a recess there is prepared (Step 1, FIG. 5 (a)). Such a wafer W is preferably one obtained by removing moisture on the insulating film surface and residues during etching / ashing by a Degas process or a Pre-Clean process. In this embodiment, such a wafer W is carried into the film forming system shown in FIG. 1, and a degas process is performed in the degas chamber 5a or 5b.

  Next, the wafer W is carried into the barrier film forming apparatus 12a or 12b, and a barrier film 204 that shields (barriers) Cu is formed on the entire surface including the surface of the trench 203 (step 2, FIG. 5B).

  The barrier film 204 preferably has a high barrier property against Cu and low resistance, and a Ti film, a TiN film, a Ta film, a TaN film, and a Ta / TaN two-layer film are preferably used. it can. Further, a TaCN film, a W film, a WN film, a WCN film, a Zr film, a ZrN film, a V film, a VN film, an Nb film, an NbN film, or the like can be used. Since the Cu wiring has a lower resistance as the volume of Cu embedded in the trench or hole increases, the barrier film is preferably formed very thin. From such a viewpoint, the thickness is preferably 1 to 20 nm. More preferably, it is 1-10 nm. The barrier film can be formed by plasma sputtering. Moreover, it can form into a film by other PVD, such as normal sputtering and ion plating, and it can also form into a film by CVD and ALD which used CVD, ALD, and plasma.

Next, the Ru liner film 205 is formed on the barrier film 204 by the Ru liner film forming apparatus 14a or 14b (step 3, FIG. 5C). The Ru liner film is preferably formed as thin as 1 to 5 nm, for example, from the viewpoint of increasing the volume of Cu to be embedded and reducing the resistance of the wiring. The Ru liner film can be suitably formed by thermal CVD using the film forming apparatus as shown in FIG. 3 using ruthenium carbonyl (Ru ₃ (CO) ₁₂ ) as a film forming material. Thereby, it is possible to form a highly pure and very thin Ru film with high step coverage. The film formation conditions at this time are, for example, a pressure in the processing vessel in the range of 1.3 to 66.5 Pa, and a film formation temperature (wafer temperature) in the range of 150 to 250 ° C. As described above, the Ru liner film 205 is a film forming material other than ruthenium carbonyl, such as (cyclopentadienyl) (2,4-dimethylpentadienyl) ruthenium, bis (cyclopentadienyl) (2, Such as 4-methylpentadienyl) ruthenium, (2,4-dimethylpentadienyl) (ethylcyclopentadienyl) ruthenium, bis (2,4-methylpentadienyl) (ethylcyclopentadienyl) ruthenium The film can also be formed by CVD or PVD using a ruthenium pentadienyl compound.

  Next, using the Cu film deposition apparatus 22a or 22b made of a plasma sputtering apparatus that is an iPVD shown in FIG. 2, a bias is applied to the mounting table of the wafer W so that Cu migrates so that Cu migrates. Is deposited and the trench 203 is embedded (step 4, FIG. 5D).

  In the plasma sputtering apparatus, by applying a bias, Cu ions emitted from the target by the plasma are attracted to the wafer W, and the film formation rate can be increased. Since the deposited Cu film is scraped off by the sputtering action (etching action) on the surface of the wafer W by ions of the gas (for example, Ar ions), the power is usually applied to the Cu film when a bias is applied. Is limited to a size that cannot be removed. Conventionally, when such PVD is used, it is known that the step coverage is poor, and pinch-off that closes the opening of the trench and hole is likely to occur. No wiring is formed.

  On the other hand, by providing a Ru liner film on the base of the Cu film, Ru has high wettability to Cu. Therefore, while the wafer W is heated to a certain temperature, the bias power is adjusted to form a film of Cu ions. By controlling the etching action of the plasma generated gas ions (Ar ions), Cu can be migrated (flowed) on the Ru liner film without agglomeration, and the trenches and holes are blocked (overhang). It has been found that Cu can be embedded therein without). Thereby, Cu can be surely embedded without generating voids even in fine trenches or holes. In addition, when Cu is embedded in PVD in this way, impurities are less pure and high purity, and the grain size is also increased. Therefore, Cu wiring having lower resistance than that in the case where Cu is embedded by plating should be formed. Can do.

  The wafer W after the Cu film is formed and Cu is buried in the trench or hole is unloaded from the film forming system 1 and transferred to the Cu plating apparatus, where the Cu plating layer is formed on the entire surface of the wafer W. 207 is formed (step 5, FIG. 5 (e)). Thereafter, annealing is performed as necessary to increase the grain size of Cu, the Cu plating layer 207 is stabilized (step 6), and then the surface of the wafer W is polished by CMP (Chemical Mechanical Polishing), and the Ru liner film 205 is polished. The barrier film 204 is completely removed (step 7, FIG. 5 (f)). As a result, the Cu film 206 remaining in the trench or hole functions as a Cu wiring.

<Description of Step 4 Cu Film Formation in the Cu Wiring Forming Method According to the First Embodiment>
Next, the formation of the Cu film in step 4 will be specifically described.
As described above, in forming the Cu film in step 4, an apparatus that performs plasma sputtering while attracting ions to the surface of the wafer W with a bias as shown in FIG. 2 is used. The relationship with the film amount is as shown in the schematic diagram of FIG. That is, since the amount of Cu ions drawn increases as the bias power increases, the amount of film formation increases until the bias power reaches a certain value, but thereafter, the wafer is generated by plasma generating gas ions (eg, Ar ions). The amount of film formation decreases due to the sputtering action (etching action) on the W surface. In this embodiment, since the Cu film is buried in the trench or via (hole) using the action of the temperature and the plasma generating gas ions, the bias power has the action of the plasma generating gas ions and the film is formed. A range that is larger than A and smaller than B in FIG. 6 is preferable. That, Cu deposition amount (film formation rate) and _{T D,} the etching amount of ions of the gas for plasma generation (etching rate) and _{T E,} A is a _{T E / T D = 0,} B is T _{Although E} 1 / T _D = 1, in order for Cu to move (migrate) on the Ru liner film, it is preferable that the energy of plasma generating gas ions (Ar gas ions) is present, so that T _E / T _D It is preferred that> 0. However, when the temperature is high, Cu can be flowed even if T _E / T _D = 0. On the other hand, it is necessary that T _E / T _D <1 so that the film formation proceeds and no field etching occurs.

  A film formation model in such a range is schematically described in FIG. As shown in FIG. 7A, when the formation of the Cu film is started while applying a bias in the presence of Cu ions and Ar ions as the plasma generation gas, as shown in FIG. Cu is etched by Ar ions, and Cu is moved into the trench by the action of temperature and Ar ions. Therefore, as shown in FIG. Can be filled.

Next, preferable process conditions for the Cu film forming step in Step 4 will be described.
In this embodiment, since it is necessary to migrate Cu by plasma generated gas ions such as Ar ions, it is necessary to make the wafer temperature higher than in the case of normal plasma sputtering, and the wafer temperature is 65 to 350 ° C. The range of is preferable. Moreover, the pressure (process pressure) in the processing container at the time of forming the Cu film is preferably 1 to 100 mTorr (0.133 to 13.3 Pa), and more preferably 35 to 90 mTorr (4.66 to 12.0 Pa). Moreover, the DC power to the Cu target is preferably 4 to 12 kW, and more preferably 6 to 10 kW.

Further, as described above, the bias power is set in the range of 0 ≦ T _E / T _D <1, preferably 0 <T _E / T _D <1, but the plasma generating gas ions (Ar gas ions) ) Depends on temperature, and if the film formation temperature T is low, the mobility of Cu becomes low. For this reason, in the preferable range of 65 ≦ T (° C.) ≦ 350, in the case of 200 <T (° C.) ≦ 350 on the high temperature side, the range of 0 ≦ T _E / T _D <1 may be satisfied, but 65 ≦ T on the low temperature side. When (° C.) ≦ 200, it is preferable to satisfy 0.02 ≦ T _E / T _D <1. The bias power density is 200 <T (℃) ≦ 350 In 1.74W / cm ² at this time (bias power: 1200 W) or less, 65 ≦ T (℃) ≦ 200 In 0.15~1.74W / ^cm 2 ( 100 to 1200 W) is preferable. A more preferable range is 0.05 ≦ T _E / T _D ≦ 0.24 at 65 ≦ T (° C.) ≦ 350, and a more preferable range of bias power density is 0.38 to 0.76 W / cm ² ( Bias power: 260 to 520 W).

  Further, the deposition rate during the Cu film deposition in step 4 is preferably 20 to 150 nm / min. A specific example is 30 nm / min.

In FIG. 8, when the Cu film is actually formed by the apparatus of FIG. 2, the horizontal axis represents the DC power supplied from the DC power source 84 to the Cu target 83, and the vertical axis represents the bias power from the high frequency power source 74. The above-mentioned values of T _E / T _D are indicated by contour lines, where (a) is a process pressure of 90 mT and (b) is a process pressure of 35 mT. The high frequency power supplied from the high frequency power supply 81 to the induction coil 80 was 4 kW, and the distance between the Cu target and the wafer W was 240 mm.

Further, FIG. 9 shows that when the Cu film is actually formed by the apparatus of FIG. 2, the horizontal axis represents the bias power and the vertical axis represents T _E / T _D for each DC power to the Cu target 83. It is a graph which shows these relations, (a) is a case where process pressure is 90 mT, (b) is a case where process pressure is 35 mT. At any pressure and direct current power to the Cu target 83, T _E / T _D is 0 when the bias power is 130 W (bias power density: 0.19 W / cm ² ), and as the bias power is increased, T _E / _{T D} is rising.

Next, after forming a Ti barrier film and a Ru liner film on an interlayer insulating film in which a trench having a width of 30 nm and a depth of 200 nm is formed, process pressure: 90 mT, DC power supplied to a Cu target: 8 kW, supplied to an induction coil High-frequency power to be applied: 4 kW, distance between target and wafer W: 240 mm, bias power is 130 W (bias power density: 0.19 W / cm ² ) at which T _E / T _D = 0, and film formation temperature is 200 ° C. Cu films were formed at 225 ° C., 250 ° C., and 300 ° C. with a film formation time of 55 sec. A scanning electron microscope (SEM) photograph at that time is shown in FIG. As shown in FIG. 10, it was confirmed that Cu can be embedded at a film formation temperature of 225 ° C. or higher and T _E / T _D = 0.

Next, after forming a Ti barrier film and a Ru liner film on an interlayer insulating film in which a trench having a width of 50 nm and a depth of 200 nm is formed, process pressure: 90 mT, DC power supplied to a Cu target: 8 kW, supplied to an induction coil RF power to be applied: 4 kW, distance between target and wafer W: 240 mm, bias power is 130 W (bias power density: 0.19 W / cm ² ), where T _E / T _D = 0, and T _E / T _D = A Cu film was formed at a film formation temperature of 65 ° C. and a film formation time of 55 seconds at 195 W (0.28 W / cm ² ), which is 0.02. A scanning electron microscope (SEM) photograph at that time is shown in FIG. As shown in FIG. 11, when the film formation temperature is 65 ° C., the effect of temperature on Cu migration is small. Therefore, at 130 W (0.19 W / cm ² ) where T _E / T _D = 0, Cu is embedded in the trench. On the other hand, it was confirmed that it was embedded at 195 W (0.28 W / cm ² ) where T _E / T _D = 0.02.

Next, after forming a Ti barrier film and a Ru liner film on an interlayer insulating film in which a trench having a width of 20 to 30 nm and a depth of 200 nm is formed, process pressure: 90 mT, DC power supplied to a Cu target: 6 kW, induction coil The high frequency power supplied to the substrate is 4 kW, the distance between the target and the wafer W is 240 mm, the bias power is 130 W (bias power density: 0.19 W / cm ² ) (T _E / T _D = 0), 260 W (0.38 W). / Cm ² ) (T _E / T _D = 0.05), 390 W (0.57 W / cm ² ) (T _E / T _D = 0.14), 520 W (0.76 W / cm ² ) (T _E / T _D = 0.24), and a Cu film was formed at a film formation temperature of 250 ° C. and a film formation time of 55 seconds. A scanning electron microscope (SEM) photograph at that time is shown in FIG. As shown in FIG. 12, Cu embedding was confirmed in the range of 0 ≦ T _E / T _D ≦ 0.24, but more preferable embedding property is obtained when 0.05 ≦ T _E / T _D ≦ 0.24. It was confirmed.

  Next, a Ti barrier film is formed on an interlayer insulating film in which a trench having a width of 18 nm and a depth of 200 nm is formed, and then a Ru liner film is formed. Thereafter, process pressure: 90 mT, DC power supplied to a Cu target: 6 kW Cu was embedded under the conditions of the present embodiment that the high frequency power supplied to the induction coil was 4 kW, and the distance between the target and the wafer W was 240 mm. FIG. 13 shows a scanning electron microscope (SEM) photograph of the state in which only the Ti barrier film is formed, the state in which the Ru liner film is formed, and the state in which the Cu film is formed to 5 nm, 10 nm, 20 nm, and 30 nm. As shown in FIG. 13, in this embodiment, it was confirmed that Cu could be embedded in a fine trench without generating a void.

  Next, the electrical characteristics of the Cu wiring formed according to the present invention and the conventional Cu wiring formed by embedding Cu by Cu plating after forming a Cu seed layer on the barrier film by PVD were compared. FIG. 14 is a diagram showing the results of evaluating the electrical characteristics of these at 60 nm wiring. As shown in this figure, it was confirmed that the Cu wiring formed according to the present invention has lower wiring resistance than the conventional one.

<Method for Forming Cu Wiring According to Second Embodiment>
Next, a Cu wiring forming method according to the second embodiment of the present invention will be described with reference to the flowchart of FIG. 15 and the process cross-sectional view of FIG. In this embodiment, a description will be given of Cu filling into a wafer including a dual damascene structure in which a recess having a trench and a via (hole) formed at the bottom of the trench is formed.

  In the present embodiment, first, a recess having a trench 303 and a via 304 in which a connection wiring to the lower wiring 301 formed at the bottom of the trench 303 is formed in the interlayer insulating film 302 on the lower wiring 301 is formed. A wafer including a dual damascene structure is prepared (step 11, FIGS. 16A and 16B). 16A is a plan view of the trench 303 and the via 304, and FIG. 16B is a cross-sectional view taken along the line XX ′ and the line YY ′ of FIG. The subsequent steps will be described with reference to cross-sectional views 16 (c) to 16 (f) taken along the line XX 'and the line YY' similar to FIG. 16 (b).

  As in the first embodiment, after the wafer W is degassed in the degas chamber 5a or 5b, a barrier film 305 that shields (barriers) Cu is formed as in the first embodiment (Step 12, Further, a Ru liner film 306 is formed on the barrier film 305 (step 13, FIG. 165 (d)).

  Next, using a Cu film deposition apparatus 22a or 22b made of a plasma sputtering apparatus that is an iPVD shown in FIG. 2, a bias is applied to the mounting table of the wafer W to form a Cu film that becomes a Cu wiring so that Cu migrates. In the present embodiment, the Cu film 307 is formed at a relatively low speed in the first stage until the filling of the via 304 is completed (step 14 and FIG. 16). (E)) In the second stage from the completion of the filling of the via 304 to the completion of the filling of the trench, a Cu film is formed at a relatively high speed (step 15, FIG. 16 (f)). That is, the film formation rate (deposition rate) in the first stage in which the vias are embedded is smaller than the second stage after the vias are embedded.

The reason for forming the film in two stages as described above is as follows.
When there is no via at the bottom of the trench, it is sufficient to bury Cu so that Cu migrates under the conditions of the first embodiment by i-PVD, and Cu is always from the field portion to the bottom of the trench 303. It is possible to set a condition where the deposition rate of Cu on the bottom of the trench 303 is high. However, in the case of the dual damascene structure in which the via 304 is formed at the bottom of the trench 303 as in the present embodiment, there is no problem at the initial stage of film formation as shown in FIG. As the film formation proceeds, as shown in FIG. 17B, the fluidity of the Cu film 307 deposited on the bottom of the trench 303 deteriorates, and an overhang 308 may be formed at the bottom of the trench 303. . When the overhang 308 is formed in this way, a pinch-off is caused and a void 309 is formed as shown in FIG.

  Therefore, in the present embodiment, as the first stage of Cu film formation, the Cu film 307 is relatively slow until the filling of the via 304 is completed so that the fluidity of Cu at the bottom of the trench 303 becomes good. Is deposited. As a result, as shown in FIGS. 18A and 18B, overhang hardly occurs at the bottom of the trench 303, and formation of voids is prevented. That is, in the first stage, Cu is deposited at a deposition rate that ensures Cu fluidity that does not cause an overhang at the bottom of the trench 303. On the other hand, after the via 304 is completely buried, as a second stage, the remaining portion of the trench 303 is buried at a relatively high deposition rate. That is, after the via 304 is completely buried, no overhang is generated at the bottom of the trench 303. Therefore, even when the deposition rate is set to be high as in the trench embedding according to the first embodiment, FIG. As shown in (c), no void is formed.

  The deposition rate of the Cu film can be controlled by changing the power applied to the Cu target 83 by the DC power source 84. That is, as the power applied to the Cu target 83 increases, the amount of Cu sputtering increases and the Cu deposition rate (that is, the film formation rate) increases. FIG. 19 shows the power of the DC power supply 84 when the pressure in the processing container is 90 mTorr (12.0 Pa), the distance between the target and the wafer W is 240 mm, and the bias power is 0 W in the film forming apparatus of FIG. Although the relationship with the Cu deposition rate is shown, it can be seen that the Cu deposition rate increases in proportion to the power of the DC power supply 84.

  When forming the Cu film, the Cu deposition rate (Cu film formation rate) until the first stage via filling is completed is preferably 5 to 20 nm / min, for example, 12 nm / min. The speed (Cu film formation speed) from the completion of the second stage via filling to the trench filling (Cu film forming speed) is preferably 20 to 150 nm / min, for example, 30 nm / min.

  In this way, after the second stage Cu film formation in Step 15, the Cu plating layer is formed (Step 16), annealed (Step 17), and the entire surface is polished by CMP (Step 17) in the same manner as in the first embodiment. 18) to form a Cu wiring.

  Note that the method according to the second embodiment has a dual recess having a trench 303 having a width of 10 to 100 nm, a trench aspect ratio of 2 to 6, and a via aspect ratio of 1.5 to 4. Effective for damascene structure. Specific examples include a recess having a trench width of 19 nm and a trench aspect ratio of 3 and a via aspect ratio of 2, and a recess having a trench width of 30 nm and a trench aspect ratio of 3 and a via aspect ratio of 2. Can do.

  Next, after forming a Ti barrier film and a Ru liner film on a wafer including a dual damascene structure having a recess having a width of 30 nm, a trench aspect ratio of 3 and a via aspect ratio of 2, a process pressure of 90 mT, Cu target The first stage Cu film is formed under the conditions of DC power to be supplied: 4 kW, high frequency power to be supplied to the induction coil: 4 kW, bias power: 200 W, distance between target and wafer W: 240 mm, temperature: 300 ° C. After the via filling is completed, the process pressure is 90 mT, the DC power supplied to the Cu target is 6 kW, the high frequency power supplied to the induction coil is 4 kW, the bias power is 390 W, the distance between the target and the wafer W is 240 mm, At the temperature of 300 ° C., the second stage Cu film formation completes the trench filling. I went to. The switching of the condition from the first stage to the second stage was performed after the elapse of time until the via embedding was completed. At this time, the film formation rate in the first stage was 12 nm / min, and the film formation speed in the second stage was 30 nm / min.

  As a result of performing cross-sectional observation after performing the two-stage film formation as described above, the dual damascene structure was embedded without forming a void in the via embedded portion.

<Other applications>
As mentioned above, although embodiment of this invention was described, this invention can be variously deformed, without being limited to the said embodiment. For example, in the above embodiment, an example in which an ICP type plasma sputtering apparatus is used for embedding Cu has been described. However, the present invention is not limited to this, and other types of plasma sputtering apparatuses may be used. Other types of PVD devices may be used as long as they can be adjusted.

  Further, the film forming system is not limited to the type as shown in FIG. 1, but may be a type in which all film forming apparatuses are connected to one transfer apparatus. Further, instead of the multi-chamber type system as shown in FIG. 1, the barrier film, the Ru liner film, and the Cu film may be formed by an apparatus provided separately.

Furthermore, in the above embodiment, an example in which the method of the present invention is applied to a wafer having a trench and a wafer including a dual damascene structure having a trench and a via formed at the bottom of the wafer has been shown. Needless to say, the present invention can be applied to concave portions having other structures, such as the case of having the concave portions. In the above embodiment, the semiconductor wafer is described as an example of the substrate to be processed. However, the semiconductor wafer includes not only silicon but also compound semiconductors such as GaAs, SiC, and GaN, and is not limited to the semiconductor wafer. Of course, the present invention can also be applied to glass substrates, ceramic substrates, and the like used in FPDs (flat panel displays) such as liquid crystal display devices.

DESCRIPTION OF SYMBOLS 1; Film-forming system 12a, 12b; Barrier film-forming apparatus 14a, 14b; Ru liner film-forming apparatus 22a, 22b; Cu film-forming apparatus 51; Processing container 56; Vacuum pump 59; Gas supply source 63; 65; Cooling jacket 74; Bias high frequency power supply 78; Plasma generation source 80; Coil 83; Cu target 84; DC power supply 85; Magnet 87; Resistive heater 201; Substructure 202; Interlayer insulating film 203; Trench 204; Ru liner film 206; Cu film 301; lower wiring 302; interlayer insulating film 303; trench 304; via 305; barrier film 306; Ru liner film 307; Cu film W;

Claims (28)

A Cu wiring forming method of forming Cu wiring by embedding Cu in a recess formed in a substrate,
Forming a barrier film on at least the surface of the recess;
Forming a Ru film on the barrier film;
Forming a Cu film so that Cu migrates by PVD while heating on the Ru film, and embedding Cu in the recess.   The method for forming a Cu wiring according to claim 1, wherein the recess is a trench or a hole. A Cu wiring forming method of forming Cu wiring by embedding Cu in a recess formed in a substrate,
Forming a barrier film on at least the surface of the recess;
Forming a Ru film on the barrier film;
A process of forming a Cu film on the Ru film so that Cu migrates by PVD while heating, and embedding Cu in the recess;
The recess has a trench and a hole formed in the bottom of the trench,
The step of forming the Cu film and embedding Cu in the recess includes a first stage until Cu is completely embedded in the hole, and after the hole is completely embedded, until the trench is completely embedded. And a second stage of
A method for forming a Cu wiring, wherein the film formation rate in the first stage is lower than the film formation speed in the second stage.   4. The method of forming a Cu wiring according to claim 3, wherein the film forming speed in the first stage is a film forming speed that ensures Cu fluidity to such an extent that no overhang occurs at the bottom of the trench. .   5. The Cu wiring according to claim 3, wherein the film formation rate in the first stage is 5 to 20 nm / min, and the film formation speed in the second stage is 20 to 150 nm / min. Forming method.   The Cu film for embedding Cu generates a plasma by a plasma generation gas in a processing container in which a substrate is accommodated, releases Cu from a Cu target, ionizes Cu in the plasma, and biases the substrate. 6. The method for forming a Cu wiring according to claim 1, wherein the Cu wiring is formed by applying electric power and drawing Cu ions onto the substrate.   The method for forming a Cu wiring according to claim 6, wherein the step of forming the Cu film and embedding Cu in the recess is performed at a substrate temperature of 65 ° C. or higher and 350 ° C. or lower. The step of forming the Cu film and embedding Cu in the concave portion is performed by setting the substrate temperature to be higher than 200 ° C. and not higher than 350 ° C., and depending on the Cu film formation amount T _D on the substrate by the Cu ions and the ions of the plasma generation gas. formation of Cu interconnect of claim 6, wherein the etching amount T _E of the Cu film is performed by adjusting the 0 ≦ T _{E /} T D <magnitude of the bias power so as to satisfy _one of the relations Method. Burying the Cu in the Cu film formed by the recess, the substrate temperature was below 200 ° C. 65 ° C. or higher, and the Cu deposition amount T _D and the plasma generation gas to the substrate by the Cu ions by ion The Cu wiring according to claim 6, wherein the bias power is adjusted so that the etching amount T _E of the Cu film satisfies a relationship of 0.02 ≦ T _E / T _D <1. Forming method. 10. The method of forming a Cu wiring according to claim 8, wherein the magnitude of the bias power is adjusted to satisfy 0.05 ≦ T _E / T _D ≦ 0.24.   The barrier film is a Ti film, TiN film, Ta film, TaN film, Ta / TaN two-layer film, TaCN film, W film, WN film, WCN film, Zr film, ZrN film, V film, VN film, Nb The method for forming a Cu wiring according to any one of claims 1 to 10, wherein the Cu wiring is selected from the group consisting of a film and an NbN film.   The method for forming a Cu wiring according to any one of claims 1 to 11, wherein the barrier film is formed by PVD.   The method for forming a Cu wiring according to claim 1, wherein the Ru film is formed by CVD.   14. The method for forming a Cu wiring according to claim 13, wherein the Ru film is formed by CVD using ruthenium carbonyl as a film forming material. A Cu film forming method for forming a Cu film for embedding Cu in a recess through a barrier film and a Ru film in a predetermined layer having a recess formed in a substrate,
A Cu film forming method, wherein a Cu film is formed so that Cu migrates by PVD while being heated on the Ru film, and Cu is embedded in the recess.   The Cu film forming method according to claim 15, wherein the recess is a trench or a hole. A Cu film forming method for forming a Cu film for embedding Cu in a recess through a barrier film and a Ru film in a predetermined layer having a recess formed in a substrate,
The recess has a trench and a hole formed at the bottom of the trench, and while heating on the Ru film, a Cu film is formed so that Cu migrates by PVD, and the recess is formed in the recess. Cu is embedded,
The formation of the Cu film has a first stage until the filling of the Cu into the hole is completed, and a second stage after the filling of the hole is completed until the filling of the trench is completed,
The Cu film forming method, wherein the film forming speed in the first stage is lower than the film forming speed in the second stage.   18. The Cu film formation speed according to claim 17, wherein the first stage film formation speed is a film formation speed that ensures Cu fluidity to such an extent that no overhang occurs at the bottom of the trench. Method.   19. The Cu film according to claim 17, wherein the film formation rate in the first stage is 5 to 20 nm / min, and the film formation speed in the second stage is 20 to 150 nm / min. The film forming method.   Plasma is generated by a plasma generation gas in a processing container in which the substrate is accommodated, Cu is released from a Cu target, Cu is ionized in the plasma, and bias power is applied to the substrate to cause Cu ions to be deposited on the substrate. 20. The method of forming a Cu film according to claim 15, wherein the Cu film is formed by being pulled into the recess and Cu is embedded in the recess.   21. The Cu film forming method according to claim 20, wherein the substrate temperature is set to 65 ° C. or higher and 350 ° C. or lower. The substrate temperature is set to more than 200 ° C. and not more than 350 ° C., and the Cu film formation amount T _D on the substrate by the Cu ions and the etching amount T _E of the Cu film by the ions of the plasma generation gas are 0 ≦ T _E / T _D <1 21. The method of forming a Cu film according to claim 20, wherein the magnitude of the bias power is adjusted so as to satisfy the relationship. The substrate temperature was below 200 ° C. 65 ° C. or higher, and the Cu ion etching amount _{T E} of the Cu film by ions of Cu deposition amount _{T D} and the plasma generation gas to the substrate by the 0.02 ≦ _T E / _{T D} 21. The method of forming a Cu film according to claim 20, wherein the magnitude of the bias power is adjusted so as to satisfy the relationship <1. The method for forming a Cu film according to claim 22 or 23, wherein the magnitude of the bias power is adjusted so as to satisfy 0.05 ≦ T _E / T _D ≦ 0.24. A film forming system for forming Cu wiring by embedding Cu in a recess formed in a substrate,
A barrier film forming apparatus for forming a barrier film on the surface of the recess;
A Ru film forming apparatus for forming a Ru film on the barrier film;
A Cu film forming apparatus that forms a Cu film by PVD on the Ru film and embeds Cu in the recess;
A film forming system comprising: a control unit configured to control the Cu film forming apparatus so that Cu is migrated and Cu is embedded in the recess while heating the substrate. .   26. The composition according to claim 25, further comprising transport means for transporting the barrier film forming apparatus, the Ru film forming apparatus, and the Cu film forming apparatus without breaking a vacuum. Membrane system.   15. A storage medium that operates on a computer and stores a program for controlling a film forming system. The program is executed by the Cu wiring forming method according to claim 1 at the time of execution. A storage medium that causes a computer to control the film forming system.   A storage medium that operates on a computer and stores a program for controlling a film forming apparatus, wherein the program is executed when the Cu film forming method according to claim 15 is executed. A storage medium characterized by causing a computer to control the film forming apparatus.