JPH07113159B2 - Plating equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a plating apparatus, and more particularly to a jet-type plating apparatus for performing high-quality and high-speed electroplating, and in particular, forming electrode bumps on a semiconductor wafer. It is suitable as a plating device.

[Conventional technology]

Conventionally, electroplating is generally performed as a method for forming electrode bumps having a size of about several tens to several hundreds of μm on a semiconductor wafer. As shown in FIG. 5, a large number of electrode bumps 2 are formed in each chip region 1a on the semiconductor wafer 1. Wiring on the wafer 1 as shown in FIG.
1d is formed, the resist layer 1c formed thereon is patterned to form a large number of recesses 1b (A in the same figure), and individual electrode bumps 2 (B in the same figure) in each recess 1b are electrodeposited. Form.

The immersion method has been most commonly used as the electroplating method. For example, as shown in FIG. 7, the wafer 1 in the state of FIG. 6 (A) is immersed as a cathode in a plating tank 5a containing a plating solution 5 and an electric current is applied between the wafer 1 and an anode 4 facing the wafer. Let the precipitation reaction. However, the immersion method requires an extremely long plating process time for forming the necessary bumps, and therefore it is necessary to perform plating processing on a large number of wafers in parallel in order to ensure productivity.

In order to eliminate such drawbacks, a jet method capable of speeding up the plating process has been developed (for example, JP-A-56-15).
2991). Eighth example of apparatus for electroplating by jet method
Shown in the figure. The wafer 1 in the state of FIG. 6A is placed in the plating cell 8 with the surface to be plated facing down. The plating solution 9 contained in the circulation tank 6 is pumped up by the pump 7, jetted from the nozzle 8a, and applied to the surface to be plated as a jet stream to perform plating.

The jet method has a plating treatment speed of 2 to 2 compared to the immersion method.
The speed can be increased to about 3 degrees. However, since the flow of the plating solution on the surface to be plated is directional, the defective formation of bumps such as the irregular bump 2a and abnormal growth bump 2b shown in FIG. It occurs at a high rate above. Further, in order to improve the quality, it is necessary to add various additives to the plating bath, which requires a great deal of cost for managing the plating bath and a lot of manual work for the plating treatment.
Automation and labor saving were extremely difficult.

[Problems to be Solved by the Invention]

It is an object of the present invention to provide a plating apparatus for performing electroplating by a jet method, which secures quality equal to or higher than that of a dipping method and has a treatment speed significantly higher than that of a conventional jet method. .

[Means for Solving the Problems]

According to the present invention, according to the present invention, in a plating apparatus for performing electroplating by jetting a plating solution onto a surface to be plated of a plating object, a group of nozzles for jetting the plating solution is arranged in a direction facing the surface to be plated. In addition, a mechanism is provided in an area covering the surface to be plated, and a mechanism for two-dimensionally swinging the surface to be plated and the nozzle group relative to the surface to be plated is provided in an airtight container,
This is achieved by a plating apparatus characterized by being provided with a device for depressurizing or pressurizing the inside of this airtight container.

In the device of the present invention, X in the plane parallel to the surface to be plated
It is convenient to perform two-dimensional rocking by combining one-dimensional rocking in the X and Y directions in the -Y Cartesian coordinate system. In this case, the plating may be performed while the ratio of the rocking speeds in the X and Y directions is kept constant, and this ratio may be changed during the plating. It is advantageous to randomly change the ratio to randomize the swing locus of the nozzle group viewed from the surface to be plated.

The nozzle group may be assembled by appropriately arranging the required number of nozzles, or may be manufactured by processing the required number of nozzle portions on a single material.

In the apparatus of the present invention, the two-dimensional swing mechanism is provided in the airtight container, and the device for depressurizing or pressurizing the airtight container is provided, so that the following operation can be obtained.

When the apparatus of the present invention is provided with a depressurization (exhaust) apparatus, by depressurizing the region where the plating solution is jetted, hydrogen gas generated by electrolysis and other gas taken in the jet can be removed. .

When the apparatus of the present invention is provided with a pressurizing device, by pressurizing the area where the plating solution is jetted, it is possible to prevent cavitation from occurring particularly when plating is performed with a jet stream of high speed.

An electrolysis electrode can be built in each nozzle of the nozzle group to enhance the uniformity of the plating current distribution over the entire surface to be plated.

[Work]

ADVANTAGE OF THE INVENTION The plating apparatus of this invention makes the flow of a plating solution uniform on a to-be-plated surface by making the nozzle group arrange | positioned in the range which covers the whole to-be-plated surface and a to-be-plated surface relatively two-dimensionally rock in parallel. Be multi-directional. As a result, it is possible to prevent bump formation defects such as irregularly shaped bumps and abnormal growth bumps, so that the processing speed can be significantly increased as compared with the conventional jet method, while ensuring the quality equal to or higher than that of the immersion method.

Furthermore, the above-mentioned two-dimensional swing mechanism is provided in the airtight container,
By providing a device for decompressing or pressurizing the inside of this airtight container, hydrogen gas generated during plating and other gas in the jet stream can be easily eliminated in the case of decompression, and cavitation can be prevented in the case of pressurization. The plating process can be sped up.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1 FIG. 1 shows an example of a plating apparatus according to the present invention.

The wafer 1 is loaded into a plating cell 10 by a loader (not shown) so that the liquid plating surface faces the porous nozzle 11. After the wafer 1 is loaded, the back surface of the wafer 1 is backed up by the cap 12 and is protected against shower pressure. The cell 10 is placed on the airtight chamber 13 and the wafer 1 is clamped by the cap, so that the shower booth 14
The inside is sealed. This perforated nozzle 11 is this shower booth 14
A link 16, which is arranged inside and is operated by a motor 15 provided orthogonally, swings in the X and Y directions in an XY coordinate plane parallel to the surface to be plated. The plating solution 21 is supplied to the multi-hole nozzle 11 through the flexible tube 17.
A wiring 18 is connected to the electrode 19 provided in the multi-hole nozzle 11, and a plating current is supplied. An airtight tank 20 is connected to the airtight chamber 13 through each pipe, and a plating solution 21 is stored in the airtight tank 20. Temperature controller 22 is plating solution 21
Is maintained at a constant temperature. The temperature control range can be arbitrarily set, for example, in the range of 10 to 50 ° C. The pump 23 pumps the plating solution 21 to the multi-hole nozzle 11, and circulates the plating solution in a direction by the switching valve 24 when preparing for plating (during loading, unloading, etc.), and switches to the direction when performing plating and changes the direction of the multi-hole nozzle. Supply the plating solution to 11 and shower.
The drain valve 25 is an airtight chamber for the plating solution 21 when showering.
A pipe for returning to the airtight tank 20 from inside 13, and the cap 12 moves up and down for the plating preparation liquid for loading and unloading the wafer 1.
Since the airtight chamber 13 is opened to the atmospheric pressure, the drain valve 25 is closed to prevent the airtight tank 20 from being opened to the atmosphere. When performing plating, the drain valve 25 is opened, and the plating solution 21 is returned from the airtight chamber 13 to the airtight tank 20. Pressure controller 26
Is a device for controlling the pressure in the cell 10, the airtight chamber 13, and the airtight tank 20, and performs a vacuum or pressurizing action. valve
27 and the valve 28 are closed at the time of plating preparation and opened at the time of plating so that the pressures of the airtight tank 20 and the cell 10 and the airtight chand 13 become the same, or the airtight tank 20 is opened to the atmosphere when opening to the atmosphere. Prevent. Atmosphere release valve
A filter 31 is provided at 29 and 30, and these valves 29 open the airtight chamber 13 and the cell 10 to the atmosphere. By controlling the operation timing of the atmosphere release valves 29 and 30, the damage of the wafer 1 due to the pressure difference between the front and back of the wafer 1 is prevented.
The power supply 32 is controlled so that the pole 33 is wired to the wafer 1 and the pole is wired to the electrode 19 in the multi-hole nozzle 11, and power is supplied after the shower acts on the wafer. Further, the poles 33 are arranged at four places on the outer periphery of the wafer 1, and by confirming the continuity of each of them before the shower, the crack of the wafer 1 and the contact state with the electrode are monitored. The cylinder 34 moves the cap 12 up and down to clamp the wafer 1 and apply a sealing force to the cap 12 when the air-tight chamber 13 is pressurized.

FIG. 2 is a view of the multi-hole nozzle 11 seen from the front, and a large number of nozzle holes 11a are arranged on the entire surface of the nozzle. Also, the multi-hole nozzle 11
Is driven by eccentric pulleys 15c and 15d as the rotating shafts 15a and 15b rotate, and is configured to swing in the X and Y directions. Further, by changing the rotation ratio of the rotating shafts 15a and 15b, Since the swing pattern can be randomized, the surface of the wafer 1 can be uniformly scanned by the shower.

FIG. 3 is a view showing a shower state on the wafer 1 by the multi-hole nozzle 11, and is a cross-sectional view around the multi-hole nozzle 11 and the wafer 1. The wafer 1 is pressed by the cap 12 so that the outer periphery of the surface to be plated is sealed by the packing 10a, and similarly contacts the pole 33. The resist 1c on the power feeding surface of the wafer 1 that is in contact with the pole 33 has been removed, and the packing 10
a works so that the plating solution does not adhere to this surface. The plating solution 21 discharged from the nozzle holes 11a flows on the surface to be plated of the wafer 1 as shown in FIG. 3, gathers in the middle of each nozzle hole, and flows down. Although uniformity occurs, since the multi-hole nozzle 11 is configured to swing in the X and Y directions, a uniform liquid flow distribution can be obtained.

An example of the operation mode of the plating apparatus described above will be described.

Conventionally, a dipping method as shown in FIG. 6 was used to perform a plating treatment on a wafer, which required a plating time of 110 minutes, by the above apparatus according to the present invention.

Example 1 The plating solution 21 was temperature-controlled by the temperature controller 22 to 30 to 33 ° C. The switching valve 24 was switched to the direction and circulated by the pump 23 to homogenize the plating solution. The composition of the plating solution is 50 g of sulfuric acid /
, Copper sulfate 100 g /, without additives. Pressure controller 26
In the airtight chamber 13 and the airtight tank 20, the atmosphere release valves 29 and 30 were opened to the atmospheric pressure. Next, the cap 1 is opened by operating the cylinder 34, the wafer 1 is set by a loading mechanism (not shown) so that the surface to be plated faces the porous nozzle 11, and the cap 1 is closed to clamp the wafer 1.

After conducting a conduction check between the four poles arranged in the cell 10 and confirming that the wafer 1 is surely in contact with each pole, the motor 15 is started to move the multi-hole nozzle 11 in the X and Y directions. Rocked to. The rotation ratio of the motor 15 is X direction: Y
Direction = 100: 97 to 100: 95.

Next, after opening the drain valve 25 and connecting the airtight chamber 13 and the airtight tank 20, the switching valve 24 is switched to, and the plating solution 21 is pressure-fed to the multi-hole nozzle 11 by the pump 23.
A plating solution of 70 / min was showered at a pressure of 1.5 kg / cm ² . After confirming these shower conditions (pressure and flow rate) with a pressure gauge and a flow meter (not shown), turn on the power supply 32 and turn on the cell 10.
Power was supplied to the inner electrode and the inner electrode of the multi-hole nozzle 11 to perform plating.

After supplying the required amount of electricity (300 coulombs), the power supply 32 was stopped, the oscillation was stopped, the switching valve 24 was switched to the side, and plating was completed.

Next, the cylinder 34 is operated to open the cap 12, and the wafer 1 is placed in the cell by an unloading device (not shown).
Unloaded from within 10.

All the above operations were performed automatically.

As a result, the plating treatment time was 5 minutes, and the speed could be increased 22 times as compared with the immersion method (110 minutes). The rate of occurrence of defective bump formation was 2%, which was equivalent to that of the immersion method.

Generally, when plating is performed, a large amount of H ₂ gas is generated on the surface to be plated, and the diameter is 100 to 200, especially for electrode bumps.
In the case of a deposit of about μ, the generated H ₂ gas and bubbles in the plating solution adhere to the surface to be plated, causing abnormal growth bumps (abnormal shape, chipping) as shown in Fig. 8. In the conventional dipping method, these defects were about several percent.

In the present invention, by swinging the shower,
Since the liquid on the surface of the wafer 1 can be effectively flowed, the adhered bubbles are swiftly swept away and separated from the plated surface of the wafer 1.

As is well known, in order to increase the plating speed, it is necessary to increase the limiting current density. In order to improve the limiting current density, it is generally known to speed up the mass transfer process, which is the rate-determining process in each plating process. In this respect, the present invention also thins the diffusion layer on the surface to be plated. As a means for this, it is possible to forcibly stir the plating solution in the vicinity of the surface to be plated. With normal stirring, however, a steady flow occurs, causing non-uniformity in the flow velocity distribution, and the limiting current density at the slowest flow velocity part. Limits the plating rate.

The present invention solves this problem by rocking the nozzle.
That is, by constantly moving the shower position, the portion having the slowest flow velocity and the portion having the fastest flow velocity are averaged, and the limiting current density is increased to the average flow velocity so that the speed can be increased.

Example 2 Next, an example of an operating mode with a further increased speed will be described.

In order to further increase the speed, in order to secure the flow velocity on the surface of the wafer 1, it is necessary to prevent the plating solution from foaming due to cavitation on the surface of the wafer 1.

The same plating treatment as in Example 1 was performed. However, the pressure controller 26 was operated to pressurize the airtight chamber 13 and the airtight tank 20 at the time of performing the plating.

In this example, plating was performed under a N ₂ gas pressure of ₂ kg / cm ² . Plating solution is 80 / min and relative pressure is 2.5kg /
The shower pressure was cm ² . Cavitation did not occur, and the plating treatment time was 2.5 minutes (current density 100 A / dm ² ). This is 44 times faster than the immersion method (110 minutes). The quality was equal or better.

Example 3 Next, an example of an operation mode of which the quality is higher than that of the immersion method will be described.

The same plating treatment as in Example 1 was performed. However, the pressure controller 26 is activated to move the airtight chamber 13 and the airtight tank 20 to 360
^The pressure was reduced to ^Torr and plating was performed. The generated H ₂ gas was quickly exhausted, and the air in the airtight chamber 13 was also prevented from being trapped during the shower, so that the occurrence rate of bump formation defects could be reduced to 0%.

Since the shower was performed under reduced pressure, the flow velocity on the surface of the wafer 1 could not be increased as much as at atmospheric pressure, and the plating time was 10 minutes.
This is 11 times faster than the immersion method.

If the plating process is performed under pressure as in this example, it is possible to sufficiently cope with the miniaturization of the electrode bumps.

The plating solution used in Examples 1 to 3 was 50 g of sulfuric acid / 100 g of copper sulfate /
It is a basic composition of, and no additive is required. Therefore, it is enough to manage the plating solution by replenishing it.
It is possible to greatly reduce the management cost.

In the present embodiment, the number of processed wafers is one in order to reduce the equipment cost, but a plurality of wafers may be processed in parallel if necessary.

In order to improve the machine cycle, it has a structure in which the rising time of the shower is shortened and the pressure change of the airtight tank 20 is prevented.However, the airtight chamber 13 and the airtight tank 20 are reduced in size.
May be integrated. For the shower, the piping system may be simplified by starting and stopping the pump instead of switching by the valve 24.

Example 2 FIG. 4 shows another example of the plating apparatus according to the present invention.

As shown in the figure, a drive unit for swinging the nozzle 11 in the XY direction is arranged outside the airtight chamber 13 with a structure such as a flexible joint 35, and dust generated from the drive unit enters the inside. If this is prevented, better results can be obtained.

〔The invention's effect〕

INDUSTRIAL APPLICABILITY The present invention is an automated plating apparatus that can significantly improve the processing speed while preventing or preventing bump formation defects and ensuring or improving quality, and improve the quality.
It makes a great contribution to productivity improvement and cost reduction.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a plating apparatus according to the present invention, FIG. 2 is a plan view of a multi-hole nozzle according to the present invention, and FIG. 3 is a multi-hole nozzle and a wafer periphery according to the present invention. FIG. 4 is a sectional view showing another example of the plating apparatus according to the present invention, FIGS. 5A and 5B are a plan view of a wafer (A) and a perspective view of a chip (B), respectively. 6A and 6B are partial cross-sectional views of the wafer in which a resist pattern has been formed (A) and after electrode bumps have been formed (B), and FIG. 7 schematically shows an immersion type electroplating apparatus. Sectional view, FIG. 8 is a sectional view showing a conventional jet-type plating apparatus, and FIG. 9 is a sectional view showing a state where plating is performed by the plating apparatus of FIG. 1 ... Wafer, 2 ... Electrode bump, 10 ... Plating cell, 11 ... Multi-hole nozzle, 15c, 15d ... Eccentric pulley.

Claims (2)

[Claims] 1. A plating apparatus for electroplating a plating solution by jetting the plating solution onto a surface to be plated of an object to be plated, the nozzle group jetting the plating solution facing the surface to be plated and covering the surface to be plated. A mechanism is provided in an airtight container, which is arranged in an area, and two-dimensionally swings the surface to be plated and the nozzle group relative to the surface to be plated, and a device for depressurizing or pressurizing the inside of the airtight container is provided. A plating device characterized in that 2. The plating apparatus according to claim 1, wherein an electrode for electrolysis is provided in each nozzle of the nozzle group.