JP4000341B2 - Semiconductor substrate plating method and plating apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor device manufacturing technique, and more particularly to a technique effective when applied to wafer plating.
[0002]
[Prior art]
A wafer for semiconductor manufacturing is subjected to a wafer processing step such as pretreatment, plating, cleaning, and drying in a pre-process, and then a post-process. Conventionally, in the plating process among these processes, the wafer processing surface is disposed on the upper part of the plating tank, the negative electrode is brought into contact with the edge of the wafer, and the positive electrode is disposed on the lower part of the plating tank. Then, a copper solution was supplied from the lower part of the plating tank toward the wafer to perform copper electrolytic plating.
[0003]
[Problems to be solved by the invention]
However, since such a conventional plating apparatus is a so-called face-down type apparatus with the process surface facing downward, gas generated during electrolytic plating tends to stay in the wiring groove formed on the process surface. Further, depending on conditions, gas may be generated from the cathode side, and such gas tends to accumulate on the upper side of the plating tank, that is, on the lower surface of the wafer. On the other hand, by blowing out the plating solution from the lower side, some of the generated gas is forced to flow out of the bath as well as the plating solution, but the gas staying in the wiring groove may not be completely removed by the jet of plating solution. In addition, there is a possibility that gas is convected in the plating solution flow due to the accumulation of spray. In particular, a wafer having a high aspect ratio has a high possibility of gas residue, and improvement thereof has been desired.
[0004]
Furthermore, since the gas has entered the wiring groove before the plating process, in the case of the face-down type, the gas in the groove is fixed to the device while being held, and it is in a state where it does not escape naturally. . Therefore, even if the plating solution is ejected from the lower side, there is a possibility that the gas cannot be exhausted sufficiently from the inside of the groove, and the plating solution does not completely enter the groove including the stay of the generated gas, and the film formation is incomplete. There was also a problem of becoming. In particular, in the case of a high aspect ratio, it has been desired that the generated gas that has entered the groove and the existing gas are difficult to be discharged and the improvement thereof is desired.
[0005]
On the other hand, when a soluble anode is used, fine particles may be generated, and if it enters the groove of the wafer, this also causes film formation defects. However, in the apparatus as described above, even if the plating solution is allowed to overflow and circulate, a part of the plating solution convects in the plating tank, so once the particulate matter is generated in the plating solution, it is difficult to discharge it. There is also a problem that the film forming process of the wafer is hindered.
[0006]
An object of the present invention is to provide a semiconductor substrate plating method and a plating apparatus capable of performing a plating process by completely discharging the gas in the wafer surface, particularly in the wiring groove thereof, with a simple configuration.
[0007]
[Means for Solving the Problems]
A method for plating a semiconductor substrate according to the present invention is a method for plating a semiconductor substrate in which a metal film is formed by plating on a semiconductor substrate disposed in a plating tank, and extends from the inner wall to the inner wall surface of the plating tank. A plating process is performed by forming a rotating flow of the plating solution above the semiconductor substrate by ejecting a plating solution in a direction.
[0008]
In this case, the semiconductor substrate is placed in the plating bath with the wiring groove formed on the semiconductor substrate facing upward, and an anode electrode is placed above the semiconductor substrate to perform the plating treatment. Alternatively, the inner wall of the plating tank may be formed in a cylindrical shape so that a rotating flow is easily formed.
[0009]
On the other hand, the semiconductor substrate plating apparatus of the present invention is a semiconductor substrate plating apparatus that forms a metal film by plating on a semiconductor substrate disposed in a plating tank, and is formed on the inner wall of the plating tank. It has a plating solution supply port for ejecting a plating solution in a direction along the inner wall surface and forming a rotating flow of the plating solution above the semiconductor substrate in the plating treatment tank.
[0010]
In this case, the semiconductor substrate is disposed in the plating bath with the wiring groove formed in the semiconductor substrate facing upward, and an anode electrode is disposed above the semiconductor substrate in the plating bath. Alternatively, the inner wall of the plating tank may be formed in a cylindrical shape so that a rotating flow is easily formed.
[0011]
Accordingly, the plating solution spreads over the semiconductor substrate without rotating the semiconductor substrate, and the plating solution forms a rotating liquid flow on the semiconductor substrate, so that the plating solution is always stirred. Therefore, it is possible to reduce the decrease in ion concentration near the semiconductor substrate and to perform good electrolytic plating. Furthermore, even if bubbles are generated on the surface of the semiconductor substrate, the bubbles are removed from the surface of the semiconductor substrate by the rotating liquid flow, so that the bubbles do not remain on the semiconductor substrate, and plating defects due to the bubbles can be prevented. it can.
[0012]
On the other hand, since the semiconductor substrate is placed with the process surface facing upward, the gas in the wiring groove is easily released into the plating solution, and the gas from the wiring groove is jetted together with the jet of plating solution. Can be discharged completely. Also, bubbles generated on the semiconductor substrate do not enter the wiring groove, and no gas remains or bubbles do not enter the wiring groove unlike the conventional face-down type device. Furthermore, even when a gas is generated from the anode side, for example, when an anode basket is used as an insoluble anode, the generated gas is not contained in the semiconductor substrate because the anode is positioned above the semiconductor substrate. It is discharged outside the plating tank without heading.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory view showing an outline of a semiconductor manufacturing apparatus to which a plating method according to the present invention is applied, FIGS. 2 to 4 are explanatory views showing a main configuration of the semiconductor manufacturing apparatus of FIG. 1, and FIG. 3 is a front view, and FIG. 4 is a right side view.
[0014]
The semiconductor manufacturing apparatus according to the present invention is an apparatus for performing a plating process for forming a copper film on, for example, an 8-inch wafer in a so-called damascene process. In the apparatus, a wafer (semiconductor substrate) 2 is placed on a disk-shaped rotary table (hereinafter abbreviated as a table) 1 and the table 2 is rotated to transfer the wafer 2 to each processing step. Yes.
[0015]
As shown in FIG. 1, the apparatus has a configuration in which a table 1 is disposed on a drive unit 3 that accommodates a motor or the like and is covered with a cover 4. 2 to 4 are views in which the cover 4 is omitted. In this case, the wafer 2 is transferred to the wafer supply unit 5 by a magazine or the like, and transferred to the table 1 by a handling device (substrate transfer device) 6 that sucks and transfers the wafer 2 by vacuum. As the table 1 rotates, the wafer 2 placed on the table 1 is transferred to the pretreatment, plating, cleaning, and drying processing steps in order without being handled as it is. Then, after the drying process is completed, it is taken out from the table 1 again by the handling device 6 and transferred to the wafer storage unit 7.
[0016]
Here, as shown in FIGS. 2 to 4, the table 1 is rotated around the rotation shaft 9 by a motor 8 disposed in the drive unit 3. At this time, the table 1 can be rotated and stopped at a predetermined angle by the indexing unit.
[0017]
On the outer peripheral side of the table 1, a plurality of wafer storage chambers (substrate storage portions) 18 are provided along the circumferential direction, which are separated from each other by the outer peripheral wall 10, the inner peripheral wall 11, and the partition walls 12 provided radially. ing. As the rotary shaft 9 rotates, these wafer storage chambers 18 rotate in the circumferential direction around the rotary shaft 9. In this apparatus, eight wafer storage chambers 18 are provided corresponding to the number of processing steps, but the number can be changed as appropriate.
[0018]
Each wafer storage chamber 18 is provided with a disk-shaped chuck table 19 on which the wafer 2 is placed. A rotating shaft 13 is provided below the chuck table 19, and the rotating shaft 13 is driven in a non-contact state by a motor 15 via a magnetic coupling 14. Thereby, even if the table 1 rotates, the chuck table 19 can be driven to rotate without interrupting the mechanical contact. The rotating shaft 13 is driven by the motor 15 by the action of the magnetic coupling 14 so that the wafer 2 placed on the chuck table 19 rotates. Note that the motor 15 is provided only at a position where processing that requires the wafer 2 to rotate is performed.
[0019]
Further, a drain port 16 for allowing a plating solution, a cleaning solution, etc. to flow out of the wafer storage chamber 18 is provided in the lower part on the inner peripheral side of the wafer storage chamber 18. Correspondingly, a drainage flow path 17 is provided for each processing step below the table 1. That is, the drain port 16 communicates with, for example, the plating solution drain channel 17 when the wafer storage chamber 18 is in the plating processing position, and the cleaning solution drain channel 17 when the wafer storage chamber 18 is in the cleaning processing position. . Therefore, each drainage is separately collected, so that different types of drainage are not mixed.
[0020]
On the other hand, around the table 1, various apparatuses for performing each processing step as a substrate processing unit are arranged at a 45 ° pitch corresponding to the formation interval of the wafer storage chambers 18. In this case, in FIG. 2, the pretreatment device 21 is at the position {circle around (2)}, the plating devices 22 a to 22 d are at the points {circle around (3)} to {circle around (6)}, the washing device 23 is at {circle around (7)}, and the drying device 24 is at {circle around (8)}. Is provided. That is, the wafer 2 placed on the table 1 is sequentially subjected to pre-processing, plating processing, cleaning processing, and drying processing as the table 1 rotates, and returns to the supply / storage position of (1).
[0021]
Here, in the semiconductor manufacturing apparatus, as the plating apparatuses 22a to 22d, a plating apparatus capable of performing the plating process with the opening of the wiring groove formed on the process processing surface of the wafer 2 facing upward is employed. 5 is an explanatory view showing the configuration of the plating apparatuses 22a to 22d, FIG. 6 is an explanatory view showing the relationship between the table 1 and the plating apparatus 22a, FIG. 7 is an explanatory view of the plating apparatus 22a as viewed from above, and FIG. FIG. 9 is an explanatory view showing the structure of the bottom surface side of the plating tank, and FIG. 10 is an explanatory view showing the structure of the supply / discharge port of the plating solution. Since the plating apparatuses 22a to 22d have the same configuration, the plating apparatus 22a will be described as an example here.
[0022]
In the plating apparatus 22a according to the present invention, the wafer 2 is placed with its process surface facing upward. That is, as shown in FIG. 8, the wiring groove 38 formed on the wafer 2 is arranged with its opening facing upward. In FIG. 8, the fine wiring grooves 38 are exaggerated for easy understanding.
[0023]
Further, in the plating apparatus 22a, the cylindrical plating tank 31 is lowered into the wafer storage chamber 18 by the elevating device 36 to perform the plating process. The plating tank 31 includes an anode basket 32 made of titanium as an anode electrode. When the plating tank 31 descends into the wafer storage chamber 18 during the plating process, the anode electrode comes above the wafer 2. . In this apparatus, a copper material 37 is accommodated in the anode basket 32 as a melting anode, and the wafer 2 is plated with copper.
[0024]
In addition, two cathode electrodes 33 made of titanium spring steel are disposed at the bottom of the plating treatment tank 31 along the circumferential direction. These cathode electrodes 33 come into contact with the upper surface of the wafer 2 when the plating tank 31 is lowered during the plating process.
[0025]
On the other hand, in the plating apparatus 22a, the chuck table 19 does not rotate, and the plating process is performed by the flow of the plating solution. As shown in FIGS. 7 and 10, here, a plating solution supply port 34 opened to the inner wall surface of the tank is provided at the lower part of the plating tank 31. A plating solution discharge port 35 opened on the inner wall surface of the tank is provided in the middle of the plating treatment tank 31 and above the plating solution supply port 34. In the plating treatment tank 31, the plating liquid is ejected from the plating liquid supply port 34 along the inner wall of the tank, and is discharged from the plating liquid discharge port 35 to the outside of the tank.
[0026]
In this case, as the plating solution is ejected from the plating solution supply port 34, a spiral rotating liquid flow as shown by an arrow in FIG. For this reason, the plating solution is evenly distributed on the wafer 2 without rotating the wafer 2, and desired electrolytic plating can be performed without unevenness. Further, the configuration for rotating the wafer 2 can be omitted, and the configuration of the apparatus can be simplified.
[0027]
As described above, in this apparatus, by employing such a plating method, it is possible to perform the plating process with the process surface of the wafer 2 facing upward, and further, on the wafer 2 without the need to rotate the wafer 2. It is possible to perform a uniform plating process on the surface. Further, unlike the conventional plating apparatus, the process surface of the wafer 2 can be placed on the table 1 with the process surface facing upward, so that in this apparatus, other processes can be performed in order while the wafer 2 is placed on the table 1. It has become.
[0028]
Therefore, processing of the wafer by the apparatus will be described next. Here, the wafer 2 is first transferred onto the table 1 from the wafer supply unit 5. That is, the wafer 2 is taken out from the wafer supply unit 5 by the handling device 6 and transferred to the chuck table 19 at the position (1) in FIG.
[0029]
When the wafer 2 is placed on the chuck table 19, the table 1 rotates by a predetermined angle (45 ° in the apparatus) and stops at the position (2). Then, a preprocessing process is performed on the wafer 2 by the preprocessing apparatus 21 at this position. On the other hand, the next wafer 2 is placed on the chuck table 19 at the position {circle around (1)}. Then, each time the table 1 rotates, the wafer 2 is transferred onto the chuck table 19 at the position {circle around (1)}.
[0030]
Next, for example, when a predetermined time such as one minute elapses and the pretreatment is completed at the position (2), the table 1 is rotated and the wafer 2 is transferred to the position (3). Then, the copper plating process is performed on the wafer 2 by the plating devices 22a to 22d between the position (3) and the position (6). At this time, in this apparatus, as described above, the plating process can be performed with the opening of the wiring groove 38 of the wafer 2 facing upward.
[0031]
That is, when the wafer 2 comes to the position of (3), the plating tank 31 is lowered by the elevating device 36 and its lower end enters the wafer storage chamber 18 so that the cathode electrode 33 contacts the upper surface of the wafer 2. Next, the plating solution is ejected from the plating solution supply port 34 along the inner wall of the tank, whereby a rotating liquid flow is generated in the plating treatment tank 31. As a result, the plating solution spreads over the wafer 2 evenly. In addition, since the plating solution forms a rotating liquid flow on the wafer 2, the plating solution is constantly stirred, and it is possible to reduce the decrease in ion concentration in the vicinity of the wafer 2 and perform good electrolytic plating. Further, even if bubbles are generated on the surface of the wafer 2, the bubbles are removed from the surface of the wafer 2 by the rotating liquid flow, so that they do not remain on the wafer 2, and plating defects due to the bubbles can be prevented.
[0032]
When the plating solution is supplied and the liquid level rises to the position of the copper material 37 in the anode basket 32, an electric current is supplied to the anode basket 32 from a power source (not shown) to start the electrolytic plating process. That is, copper elutes from the copper material 37 on the anode side, and copper is deposited on the wafer 2 on the cathode side. Excess plating solution is discharged from the plating solution discharge port 35, and is led out of the system from the discharge port 16 of the wafer storage chamber 18 through the discharge channel 17.
[0033]
At this time, in the plating apparatus, since the wafer 2 is placed with the process surface facing upward, the fine wiring groove 38 formed on the process surface is opened to the upper side of the chuck table 19. It will be on the top. Therefore, the gas in the wiring groove 38 is easily released into the plating solution here, and the gas can be completely discharged from the wiring groove 38 together with the jet of the plating solution. Also, bubbles generated on the wafer 2 do not enter the wiring groove 38, and no gas remains or bubbles do not enter the wiring groove 38 as in the conventional face-down type apparatus. Further, even when a gas is generated from the anode side, for example, when the anode basket 32 is used as an insoluble anode, the generated gas is applied to the wafer 2 because the anode is positioned above the wafer 2. Is discharged out of the plating bath 31 without heading.
[0034]
At positions {circle over (3)} to {circle around (6)}, the table 1 is rotated every predetermined time, and the wafer 2 is sequentially plated by the same processing as described above. In this way, after rotating the table 1 at a predetermined interval and performing the plating process sequentially at the positions (3) to (6), the wafer 2 is sent to the position (7) and the cleaning apparatus 23 performs the cleaning process. Is called. Then, after a predetermined time has passed, it is sent to the position {circle over (8)} and dried by the drying device 24. At this time, in the apparatus, since the plating process is also performed in a so-called face-up state, it is not necessary to invert the wafer 2 when shifting to another process, and therefore a series of processes can be performed by rotating the table 1. It is possible.
[0035]
When the series of processes (2) to (8) is completed, the wafer 2 returns to the position (1) again, and is again taken out of the table 1 by the handling device 6 and transferred to the wafer storage unit 7. After the processed wafer 2 is taken out, the unprocessed wafer 2 is carried from the wafer supply unit 5 by the handling device 6, and thereafter these processes are continuously performed while rotating the table 1.
[0036]
As described above, in this apparatus, the wafer 2 is transferred to the table 1 only once by the handling device 6, and all processes are performed. Be contained. Therefore, unlike the conventional apparatus, it is not necessary to repeat the handling for each process, and it is possible to minimize the chance of trouble during the wafer processing process. In addition, since the operation of the handling device 6 is simplified, the device configuration is also simplified.
[0037]
Furthermore, the handling device 6 is configured to handle only unprocessed wafers in a dry state and wafers in a dry state after drying processing, and does not need to handle a wafer in a wet state during processing such as plating. ing. Therefore, a vacuum device having a simple configuration can be adopted for the handling device 6, and further, it is not necessary to adopt a material or configuration having chemical resistance and liquid resistance. Therefore, the device cost can be reduced while simplifying the configuration of the device.
[0038]
It goes without saying that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention.
[0039]
【The invention's effect】
According to the present invention, the plating solution is ejected from the inner wall of the plating treatment tank in the direction along the inner wall surface, and the plating treatment is performed by forming a rotating flow of the plating solution above the wafer in the plating treatment vessel. Thus, the plating solution can be distributed evenly on the wafer without rotating the wafer. Further, since the plating solution forms a rotating liquid flow on the wafer, the plating solution is constantly stirred, and it is possible to reduce the decrease in the ion concentration near the wafer and to perform good electrolytic plating. Further, even if bubbles are generated on the wafer surface, the bubbles are removed from the wafer surface by the rotating liquid flow, so that the bubbles do not remain on the wafer, and plating defects due to the bubbles can be prevented.
[0040]
In addition, when the wafer is plated with the process surface facing upward, the gas in the wiring groove is easily released into the plating liquid, and the gas can be completely discharged from the wiring groove together with the jet of the plating liquid. . In addition, bubbles generated on the wafer do not enter the wiring groove, and no gas remains or bubbles do not enter the wiring groove unlike the conventional face-down type apparatus.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing an outline of a semiconductor manufacturing apparatus according to an embodiment of the present invention;
FIG. 2 is an explanatory diagram showing a configuration of a main part of the semiconductor manufacturing apparatus of FIG. 1, showing an outline when the semiconductor manufacturing apparatus is viewed from above.
FIG. 3 is an explanatory diagram showing a configuration of a main part of the semiconductor manufacturing apparatus of FIG. 1, and is a diagram showing an outline when the semiconductor manufacturing apparatus is viewed from the front direction;
4 is an explanatory diagram showing a configuration of a main part of the semiconductor manufacturing apparatus of FIG. 1, and shows an outline when the semiconductor manufacturing apparatus is viewed from the right side surface direction.
FIG. 5 is an explanatory view showing a configuration of a plating apparatus. FIG. 6 is an explanatory view showing a relationship between the rotary table and the plating apparatus.
FIG. 7 is an explanatory view of the plating apparatus as viewed from above.
FIG. 8 is an explanatory view of the plating apparatus as viewed from the side.
FIG. 9 is an explanatory view showing the configuration of the bottom side of the plating tank.
FIG. 10 is an explanatory diagram showing a configuration of a plating solution supply port and a plating solution discharge port of the plating apparatus.
[Explanation of symbols]
1 rotating table 2 wafer (semiconductor substrate)
3 Drive unit 4 Cover 5 Wafer supply unit 6 Handling device (substrate transfer device)
7 Wafer storage unit 8 Motor 9 Rotating shaft 10 Outer peripheral wall 11 Inner peripheral wall 12 Partition wall 13 Rotating shaft 14 Magnetic coupling 15 Motor 16 Drainage port 17 Drainage channel 18 Wafer storage chamber (substrate storage unit)
19 Chuck table 21 Pretreatment device (Pretreatment part)
22a-22d Plating equipment (plating processing part)
23 Cleaning device (cleaning part)
24 Drying equipment (drying section)
31 Plating Treatment Tank 32 Anode Basket 33 Cathode Electrode 34 Plating Solution Supply Port 35 Plating Solution Discharge Port 36 Lifting Device 37 Copper Material 38 Wiring Groove

Claims (6)

A semiconductor substrate plating method for forming a metal film by plating on a semiconductor substrate disposed in a plating tank,
A plating method for a semiconductor substrate, characterized in that a plating solution is jetted in a direction along an inner wall surface from an inner wall of the plating treatment tank to form a rotating flow of the plating solution above the semiconductor substrate to perform the plating treatment. . 2. The method of plating a semiconductor substrate according to claim 1, wherein the semiconductor substrate is disposed in the plating tank with a wiring groove formed on the semiconductor substrate facing upward, and an anode electrode is disposed above the semiconductor substrate. A method of plating a semiconductor substrate, wherein the plating process is performed by disposing the semiconductor substrate. 3. The method of plating a semiconductor substrate according to claim 1, wherein an inner wall of the plating tank is cylindrical. A semiconductor substrate plating apparatus that forms a metal film by plating on a semiconductor substrate disposed in a plating tank,
A plating solution supply port is formed on the inner wall of the plating treatment tank and ejects a plating solution in a direction along the inner wall surface to form a rotating flow of the plating solution above the semiconductor substrate in the plating treatment tank. An apparatus for plating a semiconductor substrate. 5. The plating apparatus for a semiconductor substrate according to claim 4, wherein the semiconductor substrate is disposed in the plating tank with a wiring groove formed on the semiconductor substrate facing upward, and the semiconductor substrate of the plating tank is disposed in the plating tank. An apparatus for plating a semiconductor substrate, comprising an anode electrode disposed above. 6. The semiconductor substrate plating apparatus according to claim 4 or 5, wherein an inner wall of the plating tank is cylindrical.

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