WO2014010333A1 - METHOD FOR FORMING Cu WIRING, AND COMPUTER-READABLE MEMORY MEDIUM - Google Patents

Abstract

Disclosed is a method for forming Cu wiring in which the Cu wiring is formed in a recess of a predetermined pattern formed on a substrate. This method for forming Cu wiring includes: a step for forming a barrier film on at least the surface of the recess (step 2); a step for forming, by PVD, a Cu alloy film containing an alloy component in an amount such that the electromigration resistance is higher than that of pure Cu and the resistance value is within an allowable range, and embedding the Cu alloy film in the recess having a barrier film formed on the surface (step 4); a step for forming a build-up layer on the Cu alloy film (step 5); and a step for polishing the entire surface by CMP and forming the Cu wiring in the recess (step 7).

Description

Cu wiring forming method and computer-readable storage medium

The present invention relates to a Cu wiring forming method for forming a Cu wiring in a recess such as a trench or a hole formed in a substrate, and a computer-readable storage medium.

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 demand for the reduction of wiring, there is a demand for lower wiring resistance (improvement of conductivity) and improvement of 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. A technique has been proposed in which the barrier film is removed by polishing by CMP (Chemical Mechanical Polishing) (for example, Patent Document 1).

However, the design rules of semiconductor devices are further miniaturized, and with this increase in current density, even if Cu is used as a wiring material, electromigration resistance has become insufficient. For this reason, as a technique for improving electromigration resistance and further improving the reliability of wiring, a Cu alloy (Cu—Al, Cu—Mn, Cu—Mg, Cu— A wiring formation process using a seed layer of Ag, Cu—Sn, Cu—Pb, Cu—Zn, Cu—Pt, Cu—Au, Cu—Ni, Cu—Co, etc. has been proposed (Non-patent Document 1). etc).

JP 2006-148075 A

Nogami et. Al. IEDM2010 pp764-767

However, as the design rules of semiconductor devices as described above are further miniaturized, the width of the trench and the hole diameter are several tens of nanometers. As described above, when a trench or hole is buried by Cu plating after a barrier film or seed film is formed by plasma sputtering, problems such as insufficient embeddability and generation of voids occur.

In addition, although the technique of Non-Patent Document 1 can improve electromigration resistance, Cu embedding is used, and thus the problem of embeddability is not essentially solved.

Furthermore, the alloy component and impurities in the Cu plating are contained in the wiring, which may increase the wiring resistance.

The present invention has been made in view of such circumstances, and when forming a Cu wiring in a recess such as a trench or a hole, an electromigration is prevented without generating a void or the like and suppressing an increase in wiring resistance as much as possible. It is an object of the present invention to provide a Cu wiring forming method capable of obtaining a highly resistant Cu wiring and a computer-readable storage medium storing a program for causing a Cu wiring forming system to execute the Cu wiring forming method.

In order to solve the above-mentioned problems, a first aspect of the present invention is a Cu wiring forming method for forming a Cu wiring in a recess having a predetermined pattern formed on a substrate, wherein a barrier film is formed on at least the surface of the recess. A step of forming, and a concave portion in which a Cu alloy film containing an alloy component having an electromigration resistance higher than that of pure Cu and having a resistance value in an allowable range is formed by PVD, and a barrier film is formed on the surface Cu wiring formation comprising: filling the inside with the Cu alloy film; forming a stacked layer on the Cu alloy film; and polishing the entire surface by CMP to form a Cu wiring in the recess. Provide a method.

In the present invention, it is preferable to determine the concentration of the alloy component of the target when performing PVD according to the film forming conditions so that the concentration of the alloy component of the Cu alloy film becomes a predetermined value. It is preferable to further include a step of forming a Ru film after forming the barrier film and before forming the Cu alloy film. The Ru film is preferably formed by CVD.

In the formation of the Cu alloy film, plasma is generated by a plasma generation gas in a processing container in which a substrate is accommodated, and particles are ejected from a target made of the same Cu alloy as the Cu alloy film to be obtained. It is preferably performed by a device that ionizes in plasma and applies a bias power to the substrate to draw ions onto the substrate.

The formation of the additional layer can be performed by forming a Cu alloy film or a pure Cu film by PVD. Moreover, it is preferable that the formation of the additional layer is performed by forming the same Cu alloy with the same apparatus after forming the Cu alloy film.

The Cu alloy constituting the Cu alloy film is Cu—Al, Cu—Mn, Cu—Mg, Cu—Ag, Cu—Sn, Cu—Pb, Cu—Zn, Cu—Pt, Cu—Au, Cu—Ni. , Cu—Co, and Cu—Ti can be used. Among these, Cu—Mn and Cu—Al are preferable, and Cu—Mn is particularly preferable.

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 Those selected from the group consisting of a film and an NbN film can be used.

According to a second aspect of the present invention, there is provided a computer-readable storage medium that operates on a computer and stores a program for controlling a Cu wiring forming system. Provided is a computer-readable storage medium that allows a computer to control the Cu wiring forming system so that the Cu wiring forming method according to the aspect is performed.

According to the present invention, a Cu alloy film containing an alloy component having an electromigration resistance higher than that of pure Cu and a resistance value in an allowable range is formed by PVD, and the Cu alloy film is embedded in the recess. Generation of voids as in the case of embedding by Cu plating can be prevented, and PVD has few impurities, so there is little increase in wiring resistance, high electromigration resistance, and an acceptable resistance value. The Cu alloy film can be formed with high accuracy. For this reason, it is possible to obtain Cu wiring having high electromigration resistance without generating voids or the like and suppressing increase in wiring resistance as much as possible.

It is a flowchart which shows the formation method of Cu wiring which concerns on one Embodiment of this invention. It is process sectional drawing for demonstrating the formation method of Cu wiring which concerns on one Embodiment of this invention. It is process sectional drawing for demonstrating the formation method of Cu wiring which concerns on one Embodiment of this invention. It is process sectional drawing for demonstrating the formation method of Cu wiring which concerns on one Embodiment of this invention. It is process sectional drawing for demonstrating the formation method of Cu wiring which concerns on one Embodiment of this invention. It is process sectional drawing for demonstrating the formation method of Cu wiring which concerns on one Embodiment of this invention. It is process sectional drawing for demonstrating the formation method of Cu wiring which concerns on one Embodiment of this invention. It is process sectional drawing for demonstrating the formation method of Cu wiring which concerns on one Embodiment of this invention. It is process sectional drawing for demonstrating the formation method of Cu wiring which concerns on one Embodiment of this invention. It is a figure which shows the relationship between wiring width and Mn density | concentration in wiring when only the inside of wiring is made into a Cu-Mn alloy. It is a figure which shows the relationship between wiring width | variety and Mn density | concentration in a wiring in case addition Cu is also made into Cu-Mn alloy. It is a SEM photograph which shows the embedding state at the time of performing the embedding experiment of the wiring of 20 nm width using a Cu-Mn alloy target (Mn0.2at.%). It is a top view which shows an example of the multi-chamber type film-forming system suitable for implementation of the formation method of Cu wiring concerning the embodiment of the present invention. It is sectional drawing which shows the Cu alloy film film-forming apparatus for forming Cu alloy film mounted in the film-forming system of FIG. FIG. 6 is a cross-sectional view showing a Ru film forming apparatus for forming a Ru liner film mounted in the film forming system of FIG. 5.

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

<One Embodiment of Forming Method of Cu Wiring>
First, an embodiment of a method for forming a Cu wiring will be described with reference to the flowchart of FIG. 1 and the process cross-sectional views of FIGS. 2A to 2H.

In this embodiment, first, an interlayer insulating film 202 such as a SiO ₂ film or a low-k film (SiCO, SiCOH, etc.) is provided on a lower structure 201 (details are omitted), and a trench 203 and a lower layer wiring are provided there. A semiconductor wafer (hereinafter, simply referred to as a wafer) W in which vias (not shown) for connection are formed in a predetermined pattern is prepared (step 1, FIG. 2A). 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.

Next, a barrier film 204 is formed by shielding Cu (barrier) over the entire surface including the surfaces of the trench 203 and via (step 2, FIG. 2B).

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. A TaCN film, W film, WN film, WCN film, Zr film, ZrN film, V film, VN film, Nb film, NbN film, or the like can also 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 to 10 nm. The barrier film can be formed by ionized PVD (Ionized physical vapor deposition; iPVD), for example, plasma sputtering. Further, it can be formed by other PVD such as normal sputtering, ion plating, etc., and can also be formed by CVD, ALD, or CVD or ALD using plasma.

Next, a Ru liner film 205 is formed on the barrier film 204 (step 3, FIG. 2C). 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.

Since Ru has high wettability with respect to Cu, by forming a Ru liner film on the base of Cu, it is possible to ensure good Cu mobility when forming a Cu film by the next iPVD. It is possible to make it difficult to generate an overhang that closes the opening. For this reason, Cu can be reliably embedded without generating voids even in fine trenches or holes.

The Ru liner film can be suitably formed by thermal CVD using ruthenium carbonyl (Ru ₃ (CO) ₁₂ ) as a film forming material. Thereby, a high-purity and thin Ru film can be formed with high step coverage. The film forming 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 forming temperature (wafer temperature) in the range of 150 to 250 ° C. The Ru liner film 205 is a film forming material other than ruthenium carbonyl, such as (cyclopentadienyl) (2,4-dimethylpentadienyl) ruthenium, bis (cyclopentadienyl) (2,4-methylpentadiene). Ruthenium pentadienyl compounds such as (enyl) ruthenium, (2,4-dimethylpentadienyl) (ethylcyclopentadienyl) ruthenium, bis (2,4-methylpentadienyl) (ethylcyclopentadienyl) ruthenium The film can also be formed by the CVD or PVD used.

In addition, when the opening of a trench or via is wide and it is difficult for overhang to occur, the Ru liner film 205 is not necessarily formed, and a Cu film may be formed directly on the barrier film.

Next, a Cu alloy film 206 made of a low purity Cu alloy is formed by PVD, and the trench 203 and a via (not shown) are almost completely embedded (step 4, FIG. 2D). In this case, it is preferable to use iPVD, for example, plasma sputtering.

In the case of normal PVD film formation, Cu flocculation tends to cause an overhang that blocks the opening of trenches and holes. However, using iPVD, the bias power applied to the wafer is adjusted to form a film of Cu ions. And the etching action by plasma generated gas ions (Ar ions), Cu can be moved to suppress the generation of overhangs, and even a narrow opening trench or hole can be embedded well. Can be obtained. At this time, a high temperature process (65 to 350 ° C.) in which Cu migrates is preferable from the viewpoint of obtaining good embeddability by imparting fluidity of Cu. Further, as described above, by providing the Ru liner film 205 having high wettability to Cu on the base of the Cu alloy film 206, Cu flows on the Ru liner film without agglomeration. Generation can be suppressed, and Cu can be surely embedded without generating voids.

In addition, when it is difficult to generate an overhang such as when the opening width of a trench or a hole is large, the film can be formed at a high speed by a low temperature process (−50 to 0 ° C.) in which Cu does not migrate.

In addition, 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).

Cu alloys constituting the Cu alloy film 206 include Cu—Al, Cu—Mn, Cu—Mg, Cu—Ag, Cu—Sn, Cu—Pb, Cu—Zn, Cu—Pt, Cu—Au, and Cu—. Ni, Cu—Co, Cu—Ti and the like can be mentioned. Among these, Cu—Mn and Cu—Al are preferable, and Cu—Mn is particularly preferable.

The concentration (content rate) of the alloy component at this time is set to a value that provides higher resistance to electromigration than pure Cu and provides an allowable resistance value. In other words, the presence of the alloy component improves electromigration resistance, but the resistance value decreases, so the alloy component is controlled to an amount that does not increase the resistance value to an unacceptable value while improving electromigration resistance. . However, since the value varies depending on the type of alloy component, it is preferable to set the value appropriately according to the alloy component. For example, in the case of Cu—Mn, the Mn concentration is 0.1 at. % Is sufficient, and the preferred range is 0.05 to 1 at. %. For Cu—Al alloys, the preferred range is 0.05 to 2 at. %. Further, the Cu alloy film 206 is formed by using a target made of Cu alloy to be obtained. The relationship between the alloy composition of the target and the composition of the Cu alloy film to be formed is such as pressure. Since it varies depending on the film forming conditions, it is necessary to adjust the alloy composition of the target so that a desired alloy composition can be obtained under the manufacturing conditions actually employed. The direct current power to the Cu alloy target is preferably 4 to 12 kW, and more preferably 6 to 10 kW.

After the Cu alloy is buried in the trench 203 and the via (hole) in this way, an additional layer 207 is formed on the Cu alloy film 206 in preparation for the subsequent planarization process (step 5, FIG. 2E).

The additional layer 207 may be formed by depositing the same Cu alloy film by PVD such as iPVD following the Cu alloy film 206, or a pure Cu film may be formed by PVD or plating. However, from the viewpoint of obtaining good throughput and simplifying the apparatus, the same Cu alloy film as the Cu alloy film 206 is formed by using the same PVD (iPVD) apparatus as the Cu alloy film 206 is formed. Thus, it is preferable to form the additional layer 207. Since the additional layer 207 hardly needs to consider the embedding property, it is preferable to form the stacked layer 207 at a deposition rate higher than that of the Cu alloy film 206 when forming the layer by PVD.

After forming the stacked layers 207 in this way, annealing is performed as necessary (step 6, FIG. 2F). By this annealing treatment, the Cu alloy film 206 is stabilized and the alloy component in the Cu alloy film 206 is moved to the upper surface of the film to suppress Cu electromigration.

Thereafter, the entire surface of the wafer W is polished by CMP (Chemical Mechanical Polishing), and the additional layer 207, the Ru liner film 205, and the barrier film 204 are removed and planarized (Step 7, FIG. 2G). As a result, a Cu wiring 208 is formed in the trench and the via (hole).

Thereafter, a cap layer 209 made of a dielectric material such as SiCN is formed on the Cu wiring 208 after the CMP polishing (step 8, FIG. 2H). The film formation at this time can be performed by CVD.

According to the present embodiment, since the Cu alloy film containing an alloy component whose electromigration resistance is higher than that of pure Cu and the resistance value is in an allowable range is embedded in the trench or hole by PVD, it is embedded by Cu plating. In addition, since PVD is low in impurities, PVD has a small increase in wiring resistance, high electromigration resistance, and a Cu alloy film having an allowable resistance value. The film can be formed with high accuracy. For this reason, it is possible to obtain Cu wiring having high electromigration resistance without generating voids or the like and suppressing increase in wiring resistance as much as possible.

Of the series of steps, Step 2 for forming the barrier film 204, Step 3 for forming the Ru liner film 205, Step 4 for forming the Cu alloy film 206, and Step 5 for forming the additional layer 207. Is preferably formed continuously in a vacuum without exposure to the atmosphere, but may be exposed to the air between any of these.

<Formation example of Cu alloy film>
Next, an example of forming a Cu alloy film will be described.
In Non-Patent Document 1, a Cu alloy seed is formed on a base and then embedded by Cu plating. The composition of the Cu alloy seed at this time is Cu-0.5 at% Mn and Cu-0.8 at% Mn. The Mn concentration in the case where the entire trench is made of a Cu—Mn alloy corresponding to Here, it is assumed that the Cu—Mn alloy seed layer is formed with a thickness of 30 nm, a bottom coverage of 80%, and a side coverage of 20%, Cu plating, and then Mn is uniformly diffused by annealing. It was.

FIG. 3A is a diagram showing the relationship between the wiring (trench) width and the Mn concentration in the wiring (Cu—Mn film) when only the wiring (trench) is made of a Cu—Mn alloy. FIG. 3B is a diagram showing the relationship between the wiring width (trench) width and the Mn concentration in the wiring (Cu—Mn film) when the stacked Cu (stacked layer: height 200 nm) is also a Cu—Mn alloy. is there.

For example, in FIG. 3B assuming that a Cu—Mn alloy is used up to the additional layer, the Mn concentration of the Cu—Mn alloy seed in the prior art is 0.5 at. %, When the wiring width to be embedded is smaller than 30 nm, about 0.1 at. % Of Mn is required to remain. Here, as described above, the relationship between the alloy composition of the target and the composition of the Cu alloy film to be formed varies depending on the film forming conditions such as pressure, and for example, film formation with good Cu fluidity is performed by iPVD. Therefore, it is known that when the pressure is increased to about 90 mTorr, the Mn concentration in the film is about half of the target concentration (see Japanese Patent Application Laid-Open No. 2008-210971), so the Cu—Mn alloy used in the iPVD apparatus As a target, the Mn concentration was 0.2 at. % Can be used.

<Embedment evaluation>
Next, using a Cu—Mn alloy target (Mn 0.2 at.%), A trench filling experiment with a width of 20 nm was performed. Here, a TaN underlayer film was formed at 4 nm by iPVD and a Ru liner film was formed at 2 nm by CVD, and then embedded by forming a Cu—Mn alloy film at 20 nm by iPVD under the following conditions.
Pressure: 12Pa
Target DC current: 7kW
Bias high frequency power: 4kW
Processing temperature: 250 ° C

As a result, as shown in the scanning electron microscope (SEM) photograph of FIG. 4, it was confirmed that the 20 nm wide trench was sufficiently embedded.

<Deposition System Suitable for Implementation of Embodiment of the Present Invention>
Next, a film forming system suitable for carrying out the Cu wiring forming method according to the embodiment of the present invention will be described. FIG. 5 is a plan view showing an example of a multi-chamber type film forming system suitable for carrying out the Cu wiring forming method according to the embodiment of 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 pure Cu film and a Cu alloy film, and a carry-in / out unit 4. In order to form the Cu wiring on the wafer W, the process up to the formation of the additional layer in the above embodiment is performed.

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. The film forming apparatuses 12a and 12b and the two Ru liner film forming apparatuses 14a and 14b are included. 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 5a and 5b for degassing the wafer W are connected to the wall portions corresponding to the other two sides of the first vacuum transfer chamber 11, respectively. 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 each side of the first vacuum transfer chamber 11 via the gate valve 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. Among them, 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 that loads and unloads the wafer W with respect to the delivery chamber 5 is provided. 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 rotate and expand / contract, and a wafer is attached to the tip of the rotation / extension / contraction part 17. 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 Cu alloy connected to a second vacuum transfer chamber 21 having an octagonal plan shape and walls corresponding to two opposing sides of the second vacuum transfer chamber 21. Two Cu alloy film forming apparatuses 22a and 22b for forming a film and two Cu film forming apparatuses 24a and 24b for forming a pure Cu film or a Cu alloy film are provided.

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

The Cu alloy film forming apparatuses 22a and 22b, the Cu film forming apparatuses 24a and 24b, the degas chambers 5a and 5b, and the load lock chamber 6 are connected to each side of the second vacuum transfer chamber 21 through a gate valve G. These are communicated with the second vacuum transfer chamber 21 by opening the corresponding gate valve, and are shut off from the second vacuum transfer chamber 21 by closing the corresponding gate valve G. The delivery chamber 5 is connected to the second transfer chamber 21 without a gate valve.

The inside of the second vacuum transfer chamber 21 is maintained in a predetermined vacuum atmosphere, among which are Cu alloy film forming apparatuses 22a and 22b, Cu film forming apparatuses 24a and 24b, and a degas chamber 5a. 5b, a second transfer mechanism 26 for carrying the wafer W in and out of the load lock chamber 6 and 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 rotate and extend / contract, and a wafer is attached to the tip of the rotation / extension / contraction part 27. Two support arms 28a and 28b for supporting W are provided, and these two support arms 28a and 28b are attached to the rotation / extension / contraction part 27 so as to face opposite directions.

The loading / unloading unit 4 is provided on the opposite side to the second processing unit 3 with the load lock chamber 6 interposed therebetween, and has an atmospheric transfer chamber 31 to which the load lock chamber 6 is connected. A gate valve G is provided on the wall portion between the load lock chamber 6 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 chamber 6 is connected. 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 chamber 6 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 above recipe is stored in the storage medium 43a 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 6. After the pressure is reduced to the same degree as the second vacuum transfer chamber 21, the wafer W in the load lock chamber 6 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 5a (5b) 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 the barrier film as described above is formed. Form a film. 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 the Ru liner film as described above is formed. To do. 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 alloy film forming apparatus 22a or 22b through the second vacuum transfer chamber 21, thereby forming the above-described Cu alloy film. Thereafter, a stacked layer is formed on the Cu alloy film. The stacked layer may be formed by continuously forming the Cu alloy film in the same Cu alloy film forming apparatus 22a or 22b. The wafer W is taken out from the Cu alloy film forming apparatus 22a or 22b by the second transport mechanism 26 and loaded into the Cu film forming apparatus 24a or 24b, where a pure Cu film or Cu alloy film is formed to form an additional layer. Also good.

After forming the additional layer, the wafer W is transferred to the load lock chamber 6 and the load lock chamber 6 is returned to atmospheric pressure. Then, the wafer W on which the Cu film is formed is taken out by the transfer mechanism 36 for atmospheric transfer, and the carrier C Return to. Such a process is repeated for the number of wafers W in the carrier.

According to the film forming system 1, the barrier film, the liner film, the Cu alloy film, and the additional layer are formed in vacuum without opening to the atmosphere, so that the oxidation at the interface of each film can be prevented, and the high performance Cu wiring can be obtained.

In addition, when forming the additional layer by Cu plating, the wafer W is unloaded after the Cu alloy film is formed.

<Cu alloy film deposition system>
Next, a preferred example of the Cu alloy film forming apparatus 22a (22b) for forming the Cu alloy film will be described.
FIG. 6 is a cross-sectional view showing an example of a Cu alloy film forming apparatus. Here, an ICP (Inductively Coupled Plasma) type plasma sputtering apparatus which is iPVD will be described as an example of the Cu alloy film forming apparatus.

As shown in FIG. 6, this Cu alloy film forming apparatus 22a (22b) has 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, for example, 13.56 MHz.

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 portion 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.

Also, immediately below the transmission plate 76, a baffle plate 82 made of, for example, aluminum is provided to diffuse the introduced high-frequency power. At the lower part of the baffle plate 82, for example, a target 83 made of an annular (a truncated cone-shell) Cu alloy is provided so as to surround the upper side of the processing space S, for example, with a cross section inclined inward. The 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. The target 83 is formed of the same kind of Cu alloy as the Cu alloy film.

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

Further, a cylindrical protective cover member 86 made of, for example, aluminum or copper is provided below the 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.

Note that each component of the Cu alloy film forming apparatus is also controlled by the control unit 40 described above.

In the Cu alloy film forming apparatus configured as described above, the wafer W is loaded into the processing container 51 shown in FIG. 6, 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 temperature of the mounting table 63 is controlled 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 a thermocouple (not shown).

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, DC power is applied from the variable DC power source 84 to the target 83, and further, 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, 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 target 83 and are attracted to the target 83. The target 83 is sputtered and particles are released. At this time, the amount of particles emitted is optimally controlled by the DC voltage applied to the target 83.

Further, most of the particles from the sputtered target 83 are ionized when passing through the plasma. Here, the particles emitted from the target 83 are scattered in a downward direction in a state where ionized particles and electrically neutral atoms are mixed. In particular, by increasing the pressure in the processing vessel 51 to some extent and thereby increasing the plasma density, the 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.

When ions enter the region of an ion sheath having a thickness of about several millimeters formed on the surface of the wafer W by the high frequency power for bias applied from the high frequency power source 74 to the electrode 66b of the electrostatic chuck 66, the ions are strongly directed. The Cu alloy film is formed by being attracted so as to accelerate toward the wafer W and deposited on the wafer W.

At this time, the wafer temperature is set high (65 to 350 ° C.), and the bias power applied to the electrode 66b of the electrostatic chuck 66 from the bias high-frequency power source 74 is adjusted to form a Cu alloy film and Ar. By adjusting the etching to improve the fluidity of the Cu alloy, it is possible to embed the Cu alloy with a good embedding property even in the case of a trench or hole having a narrow opening. Specifically, Cu alloy deposition amount (film formation rate) and _{T D,} the etching amount of ions of the gas for plasma generation (etching rate) and _{T E, 0 ≦ T E /} T D <1, further Is preferably adjusted so that 0 <T _E / T _D <1.

From the viewpoint of obtaining good embedding properties, the pressure in the processing vessel 51 (process pressure) is preferably 1 to 100 mTorr (0.133 to 13.3 Pa), more preferably 35 to 90 mTorr (4.66 to 12.0 Pa). The DC power to the target is preferably 4 to 12 kW, more preferably 6 to 10 kW.

When the trench or hole opening is wide, the wafer temperature can be set low (−50 to 0 ° C.) and the pressure in the processing vessel 51 can be lowered to form a film. Thereby, the film formation rate can be increased. In such a case, not only iPVD but also normal PVD such as normal sputtering and ion plating can be used.

<Cu film deposition system>
As the Cu film forming apparatus 24a (24b), an apparatus similar to the Cu alloy film forming apparatus 22a (22b) shown in FIG. 6 can be basically used. At this time, the material of the target 83 may be appropriately adjusted according to the film to be obtained. Further, when emphasis is not placed on embedding, not only iPVD but also normal PVD such as normal sputtering and ion plating can be used.

<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. 7 is a cross-sectional view showing an example of a Ru liner film forming apparatus, in which a Ru film is formed by thermal CVD.

As shown in FIG. 7, this Ru liner film forming apparatus 14a (14b) has a processing container 101 formed in a cylindrical body with, 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. As the gas for forming the Ru film, as described above, ruthenium carbonyl (Ru ₃ (CO) ₁₂ ) can be cited as a preferable gas. This ruthenium carbonyl can form a Ru film by thermal decomposition.

An exhaust port 111 is provided at the bottom of the processing vessel 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 film formation of the Ru film, other film forming materials other than ruthenium carbonyl, for example, a ruthenium pentadienyl compound as described above can be used together with a decomposition 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.

<Apparatus used for other processes>
The above-described film forming system 1 can perform formation of additional layers in the above embodiment, but the subsequent annealing process, CMP process, and cap layer film forming process are performed after the wafer W is unloaded from the film forming system 1. In contrast, an annealing apparatus, a CMP apparatus, and a cap layer film forming apparatus can be used. These apparatuses may have a configuration that is usually used. By forming a Cu wiring forming system with these apparatuses and the film forming system 1 and controlling them collectively by a common control unit having the same function as the control unit 40, the method shown in the above embodiment is performed. A single recipe can be used for batch control.

<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, the film forming system is not limited to the type as shown in FIG. 5, 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. 5, only a part of the barrier film, Ru liner film, pure Cu film (pure Cu seed film), and Cu alloy film is formed by the same film forming system. Alternatively, the film may be formed through exposure to the atmosphere with an apparatus provided with the remaining part, or all may be formed through exposure to the atmosphere with a separate apparatus.

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 via (hole) has been shown. However, the present invention can be applied to a case having only a trench or a case having only a hole. Needless to say. Further, the present invention can be applied to embedding in devices having various structures such as a single damascene structure, a double damascene structure, and a three-dimensional mounting structure. 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 alloy film-forming apparatus, 24a, 24b; Cu film-forming apparatus, 201; Substructure 202; interlayer insulating film 203; trench 204; barrier film 205; Ru liner film 206; Cu alloy film 207; additional layer 208; Cu wiring 209; cap layer W; semiconductor wafer ( Substrate)

Claims (12)

A Cu wiring forming method for forming a Cu wiring in a recess of a predetermined pattern formed on a substrate,
Forming a barrier film on at least the surface of the recess;
A Cu alloy film containing an alloy component having an electromigration resistance higher than that of pure Cu and having a resistance value in an allowable range is formed by PVD, and the Cu alloy is formed in the recess where the barrier film is formed on the surface. Embedding with a film;
Forming a stacked layer on the Cu alloy film;
And forming a Cu wiring in the recess by polishing the entire surface by CMP. The method for forming a Cu wiring according to claim 1, wherein the concentration of the alloy component of the target when performing PVD is determined according to the film forming conditions so that the concentration of the alloy component of the Cu alloy film becomes a predetermined value. The method for forming a Cu wiring according to claim 1, further comprising a step of forming a Ru film after forming the barrier film and before forming the Cu alloy film. 4. The method of forming a Cu wiring according to claim 3, wherein the Ru film is formed by CVD. In the formation of the Cu alloy film, plasma is generated by a plasma generation gas in a processing container in which a substrate is accommodated, and particles are ejected from a target made of the same Cu alloy as the Cu alloy film to be obtained. The method for forming a Cu wiring according to claim 1, wherein the Cu wiring is formed by an apparatus that is ionized in plasma and applies a bias power to the substrate to draw ions onto the substrate. 2. The method for forming a Cu wiring according to claim 1, wherein the additional layer is formed by forming a Cu alloy film or a pure Cu film by PVD. The method for forming a Cu wiring according to claim 1, wherein the additional layer is formed by forming the same Cu alloy with the same apparatus after forming the Cu alloy film. The Cu alloy constituting the Cu alloy film is Cu—Al, Cu—Mn, Cu—Mg, Cu—Ag, Cu—Sn, Cu—Pb, Cu—Zn, Cu—Pt, Cu—Au, Cu—Ni. The method for forming a Cu wiring according to claim 1, wherein the method is selected from Cu, Cu-Co, and Cu-Ti. The method for forming a Cu wiring according to claim 8, wherein the Cu alloy constituting the Cu alloy film is Cu-Mn. The method for forming a Cu wiring according to claim 8, wherein the Cu alloy constituting the Cu alloy film is Cu-Al. 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 claim 1, wherein the Cu wiring is selected from the group consisting of a film and an NbN film. A computer-readable storage medium that operates on a computer and stores a program for controlling a Cu wiring forming system, wherein the program is executed when the Cu wiring forming method according to claim 1 is executed. A computer-readable storage medium that causes a computer to control the Cu wiring formation system.

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