JP2000273693A - Cup-type plating equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide cup-type plating equipment in which the inside of a plating tank is partitioned off with a diaphragm and the isolation of electrolytic solutions by means of a diaphragm is secured and plating treatment can be performed without causing mutual mixing of the isolated electrolytic solutions. SOLUTION: In the cup-type plating equipment, plating can be applied to a wafer 2 by feeding a plating solution to the wafer 2 which is placed on the opening of a plating tank 1 from a solution feed tube 3 provided to the central bottom of the plating tank 1 and also by polarizing an anode 5 provided inside the plating tank 1 and the wafer 2 connected to a cathode. Further, the anode 5 and the wafer 2 are isolated from each other by means of an electrically conductive diaphragm 6 provided inside the plating tank 1, and a wafer-side isolation chamber 8 and an anode-side isolation chamber 9 are formed. In this case, respective liquid pressures of the electrolytic solutions filling the wafer-side isolation chamber 8 and the anode-side isolation chamber 9, respectively, are detected, and respective liquid pressures of both isolation chambers 8, 9 are nearly equalized by liquid pressure control means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plating apparatus for plating a semiconductor wafer,
In particular, it relates to a cup-type plating apparatus.

[0002]

2. Description of the Related Art A cup-type plating apparatus is known as an apparatus for plating a semiconductor wafer. This cup-type plating apparatus generally supplies an electrolytic solution to a wafer placed in an opening of a plating tank from a liquid supply pipe provided at a central bottom of the plating tank, and an anode provided in the plating tank. And a wafer connected to the cathode, thereby plating the wafer. This plating apparatus is widely used because it is suitable for small-lot production and can automate a plating process.

[0003] However, this cup-type plating apparatus also has points to be improved. For example, when performing a plating process, a film such as a black film is formed on the anode surface, which peels off and mixes as an impurity in the electrolytic solution, and the impurities that reach the surface to be plated of the wafer have uneven plating properties. That is what can cause it to hit.

In addition, when an insoluble anode is used in a cup-type plating apparatus, the additives present around the insoluble anode are decomposed instead of dissolving the anode metal during the plating process, and the control of the plating properties and the like is well performed. This may cause problems in management and cost.

In consideration of such a point, Japanese Patent Laid-Open Publication No. Sho 62-36529 discloses that an anode and a wafer are separated from each other by disposing a conductive diaphragm in a plating tank.
A technique as disclosed in Japanese Patent Application Laid-Open No. 242797 or the like has been proposed. In this technology, an electroconductive diaphragm divides the inside of a plating tank into a wafer-side isolation chamber formed above the diaphragm and an anode-side isolation chamber formed below the diaphragm, and an electrolytic solution that fills both isolation chambers. To prevent impurities from coming into contact with the wafer,
It is excellent in preventing deterioration of the electrolyte.

[0006] By the way, as a diaphragm for partitioning the inside of the plating tank, for example, a hydrophilic Teflon diaphragm having a fine pore structure is used. Such a diaphragm also has electrical conductivity in the electrolyte and has excellent characteristics of isolating the electrolyte in both isolation chambers. However, when the electrolytes separated by the diaphragm have different hydraulic pressures, the electrolyte may pass through the micropores of the diaphragm and cause mixing of the separated electrolytes. That is, the function of the diaphragm for isolating the electrolytic solution is not sufficiently exhibited, and it may be insufficient to prevent impurities from being mixed into the electrolytic solution or to prevent the entire electrolytic solution from deteriorating.

[0007]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a cup-type plating apparatus in which the inside of a plating tank is partitioned by a diaphragm, whereby the separation of the electrolytic solution by the diaphragm is ensured, and the separated electrolytic solutions are separated from each other. An object of the present invention is to provide a cup-type plating apparatus capable of performing a plating process without mixing.

[0008]

In order to solve the above-mentioned problems, the present invention supplies an electrolytic solution to a wafer placed in an opening of a plating tank from a liquid supply pipe provided at a central bottom of the plating tank. At the same time, the wafer is plated by polarizing the wafer connected to the anode and the cathode provided in the plating tank, and the anode and the wafer are electrically conductive provided in the plating tank. Separated from each other by a diaphragm, a wafer-side isolation chamber is formed above the diaphragm, and an anode-side isolation chamber is formed below the diaphragm. A fluid pressure sensor for detecting fluid pressure is provided, and fluid pressure control means, which receives a signal detected by the fluid pressure sensor and adjusts a supply amount of the electrolytic solution in each of the isolation chambers, provides a two-way separation. It was to have been the chamber of hydraulic pressure to be substantially equal.

According to the cup-type plating apparatus of the present invention, in the isolation chamber on the wafer side and the isolation chamber on the anode side in the plating tank defined by the diaphragm, the pressure of the electrolyte filling the two isolation chambers is increased. The supply amount of the electrolytic solution is adjusted so that the liquid pressure in both the isolation chambers is substantially equalized by the sensor, and the liquid pressure of the electrolytic solution in the two isolation chambers is controlled so as to be substantially equal. Therefore, the electrolyte filling the two isolation chambers does not mix with each other after passing through the membrane. As a result, it is possible to completely prevent impurities from being mixed into the electrolytic solution and deterioration of the electrolytic solution, and it is possible to perform a stable plating process without distinguishing a soluble anode or an insoluble anode.

When the cup-type plating apparatus of the present invention is employed, the diaphragm is provided with a slope which rises from the liquid supply pipe toward the outer periphery, and the plating tank is collected on the anode side of the upper end of the diaphragm. It is preferable that a gas discharge hole is provided at a position where the bubble can escape. In this way, the valves generated from the anode gather along the slope of the diaphragm on the anode side at the upper end of the diaphragm,
The gas escapes from the gas release hole provided below the joint position between the diaphragm and the inner surface of the plating tank. Therefore, since bubbles do not stay in the anode-side isolation chamber, it is possible to prevent a decrease in electrolysis efficiency due to the influence of the valve.

Further, when the cup-type plating apparatus of the present invention is adopted, the electrolytic solution supplied to the isolation chamber on the wafer side contains metal ions to be plated on the wafer, and the electrolytic solution supplied to the isolation chamber on the anode side is used. It is preferable that the liquid does not contain metal ions to be plated on the wafer. In this case, the amount of the electrolytic solution containing metal ions to be plated on the wafer, that is, the amount of the plating solution itself can be reduced, which is advantageous in cost. Further, in the cup-type plating apparatus of the present invention, since the electrolytes in both the isolation chambers are prevented from being mixed, the composition of the electrolyte supplied to the anode-side isolation chamber is supplied to the wafer-side isolation chamber. It can be adjusted freely without being restricted by the electrolyte solution to be used. Therefore, it is also possible to suppress the generation of bubbles from the anode by adding a reducing agent or the like to the electrolyte in the anode-side isolation chamber. Here, the metal ions to be plated on the wafer, for example, when the electrolytic solution supplied to the wafer side isolation chamber is a copper sulfate solution, refers to the Cu ions in the copper sulfate solution, in which case the supply to the anode side isolation chamber The electrolytic solution used is C
This indicates, for example, an aqueous sulfuric acid solution that does not contain u ions.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the cup-type plating apparatus according to the present invention will be described below.

FIG. 1 schematically shows a section of a plating tank of a cup-type plating apparatus according to the present embodiment. As shown in FIG. 1, the cup-type plating apparatus according to the present embodiment places a wafer 2 along an opening of a plating tank 1, and in this state, performs plating on a plating target surface on a lower surface of the wafer 2. It has become. A cathode (not shown) is provided in the opening of the plating tank 1, and the wafer 2 placed in the opening comes into contact with the cathode.

At the center of the bottom of the plating tank 1, a liquid supply pipe 3 connected to an external supply means is provided. In addition, at the upper end of the plating tank 1, a plating solution (copper sulfate solution) reaching the vicinity of the center of the plating target surface overflows so as to form a flow that spreads in a direction toward the outer periphery of the wafer 2. An outlet 4 is provided. The liquid discharge port 4 is connected to the liquid supply pipe 3 through a path (not shown), thereby forming a first path for plating solution circulation. Further, around the liquid supply pipe 3 inside the plating tank 1, P
A disk-shaped anode 5 formed insoluble with t / Ti is provided.

In the present embodiment, the diaphragm 6 is provided with the liquid supply pipe 3.
Are arranged in such a manner as to be inclined upward in the direction from the periphery to the outer periphery, and are joined to the inner peripheral surface 7 of the plating tank.
Due to the diaphragm 6, the inside of the plating tank 1 is partitioned into a wafer-side isolation chamber 8 and an anode-side isolation chamber 9 above the diaphragm.

A gas discharge hole 10 for removing bubbles generated from the anode 5 and collected on the lower surface side of the diaphragm 6 is formed in the inner peripheral surface 7 of the plating tank 1 directly under the diaphragm 6. This gas discharge hole 10 is connected at its tip to a liquid storage chamber 11. The liquid storage chamber 11 is provided with a gas venting path 12 on the upper side, so that the gas discharged in the liquid storage chamber 11 can be discharged to the outside. Liquid storage room 1
A discharge path 13 for feeding the accumulated plating solution to a path (not shown) is provided below the second plating liquid. An auxiliary liquid supply pipe 14 for supplying a sulfuric acid aqueous solution as an electrolytic solution is provided in the anode-side isolation chamber 9 from the bottom outside of the plating tank 1. The auxiliary liquid supply pipe 14 is connected to the liquid storage chamber 1 described above.
1 through a discharge path 13 and a path (not shown), which forms a second path for circulating an electrolyte (aqueous sulfuric acid solution). The second path for circulating the plating solution and the first path are provided independently of each other. Although not shown, supply pumps capable of controlling the flow rates when supplying the plating solution (copper sulfate solution) and the electrolytic solution (sulfuric acid aqueous solution) are provided in each path.

Further, the plating tank 1 has a wafer-side liquid pressure detecting hole 15 for detecting a plating solution pressure in the wafer-side isolation chamber 8 and an electrolyte solution pressure in the anode-side isolation chamber 9. An anode-side hydraulic pressure detection hole 16 is provided. The wafer-side hydraulic pressure detection hole 15 and the anode-side hydraulic pressure detection hole 16 are each provided with a hydraulic pressure sensor (not shown). The signal of the hydraulic pressure sensor from the wafer-side hydraulic pressure detection hole 15 is a supply pump in the first path, and the signal of the hydraulic pressure sensor from the anode-side hydraulic pressure detection hole 16 is a supply pump in the second path. Each is sent to a pump control device (not shown) so that it can be controlled.

In the cup-type plating apparatus according to the present embodiment, the fluid pressure in the wafer-side isolation chamber 8 and the anode-side isolation chamber 9 controls the flow rates of the plating solution and the electrolytic solution supplied to the two isolation chambers 9 and 10. As a result, the plating solution and the electrolytic solution do not mix through the diaphragm. Therefore, in the cup-type plating apparatus according to the present embodiment, it is possible to completely prevent the contamination of the plating solution and the deterioration of the plating solution, and to perform a stable plating process.

[0019]

According to the cup type plating apparatus of the present invention,
The separation of the electrolytic solution by the diaphragm can be surely performed, and the plating treatment can be performed without causing the contamination of the electrolytic solution or the deterioration of the electrolytic solution.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a preferred embodiment of a cup-type plating apparatus according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plating tank 2 Wafer 3 Liquid supply pipe 4 Liquid discharge port 5 Anode 6 Diaphragm 7 Inner peripheral surface 8 Wafer side isolation chamber 9 Anode side isolation chamber 10 Gas outlet 11 Liquid storage chamber 12 Gas vent path 13 Discharge path 14 Auxiliary liquid supply Tube 15 Wafer side hydraulic pressure detection hole 16 Anode side hydraulic pressure detection hole

Claims (3)

[Claims] 1. A wafer connected to an anode and a cathode provided in a plating tank, while supplying an electrolytic solution to a wafer placed in an opening of the plating tank from a liquid supply pipe provided in a center bottom of the plating tank. The anode and the wafer are separated from each other by an electrically conductive diaphragm provided in a plating tank, and a wafer-side isolation chamber is formed above the diaphragm. In a cup-type plating apparatus in which an anode-side isolation chamber is formed below each, a liquid-pressure sensor for detecting a liquid pressure of an electrolytic solution filling the wafer-side isolation chamber and the anode-side isolation chamber is provided. The liquid pressure control means is adapted to adjust the liquid pressure of the electrolytic solution in each of the isolated chambers in response to the signal thus obtained, so that the liquid pressures in the two isolated chambers are made substantially equal. -Up type plating apparatus. 2. The diaphragm is provided with a gradient rising in a direction from the liquid supply pipe toward the outer periphery, and the plating tank is provided with:
The cup-type plating apparatus according to claim 1, wherein a gas discharge hole is provided at a position through which bubbles collected on the anode side of the upper end portion of the diaphragm pass through. 3. The electrolytic solution supplied to the wafer side isolation chamber contains metal ions to be plated on the wafer, and the electrolytic solution supplied to the anode side isolation chamber contains metal ions to be plated on the wafer. The cup-type plating apparatus according to claim 1 or 2, wherein the cup-type plating apparatus is not provided.