JP2003183895A - Plating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plating apparatus in which a plating liquid is hardly deteriorated. <P>SOLUTION: This plating apparatus is equipped with a plating tank 1 for plating an object to be treated, a recovery tank 5 arranged so as to surround the plating tank 1, and a storage tank 2 arranged at a position lower than both the plating tank 1 and the recovery tank 5. The storage tank 2 is connected to the plating tank 1 by a liquid-lifting pipe 3 via a pump 6. At a position above the storage tank 2 and below the recovery tank 5, a buffer tank 7 is arranged, to which the recovery tank 5 is connected by a reflux pipe 8. The buffer tank 7 is connected to the storage tank 2 by a reflux pipe 4 via a valve 13. At the side of the buffer tank 7, a liquid level sensor 10 for obtaining information on the liquid level of the plating liquid in the buffer tank 7 is arranged, and the output signal of the liquid level sensor 10 is inputted into a control unit 14 which opens and closes the valve 13 basing upon the output signal of the liquid level senor 10. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a plating apparatus for plating an object to be treated while circulating a plating solution.

[0002]

2. Description of the Related Art For example, in a manufacturing process of a semiconductor substrate, one surface of the semiconductor substrate may be plated. FIG. 2 is a schematic sectional view showing the structure of a conventional plating apparatus for plating a semiconductor substrate. This plating apparatus is provided with a plating tank 31 for performing a plating process on a semiconductor substrate W, a recovery tank 35 arranged so as to surround the plating tank 31, a plating tank 31 and a position lower than the recovery tank 35, and a large amount. And a storage tank 32 for storing the plating solution. The lower portion of the side surface of the storage tank 32 and the central portion of the bottom surface of the plating tank 31 are connected by a pumping pipe 33. A pump 36 is interposed in the pumping liquid pipe 33,
The plating solution in 2 can be pumped up to the plating tank 31.

From the bottom surface of the recovery tank 35, a return pipe 34 extends into the storage tank 32. The reflux pipe 34 is designed to have a sufficiently large diameter so that the plating solution can flow at a flow rate equal to or higher than the flow rate of the plating solution sent to the plating tank 31 by the pump 36. Prevents the plating solution from overflowing. In the storage tank 32,
Further, the nitrogen gas introduction pipe 45 connected to the nitrogen gas supply source, and the leak pipe 4 opened to the outside of the storage tank 32.
6 has been introduced.

Prior to performing the plating process, first, nitrogen gas is introduced into the storage tank 32 from the nitrogen gas introduction pipe 45, and accordingly, the gas in the storage tank 32 is leaked to the outside from the leak pipe 46. It By continuing the introduction of nitrogen gas for a certain period of time, the space above the plating solution in the storage tank 32 is replaced with nitrogen gas. Next, when the pump 36 is operated, the plating solution is pumped up from the storage tank 32 to the plating tank 31 via the pumping pipe 33, overflows from the edge of the plating tank 31 to the recovery tank 35, and the reflux pipe 34 flows. After that, it flows down to the storage tank 32 by the action of gravity.

When the plating solution is circulating, the plating solution is slightly raised from the edge of the plating tank 31. The semiconductor substrate W is lowered from above the plating bath 31,
By bringing the lower surface of the semiconductor substrate W into contact with this raised plating solution, one surface of the semiconductor substrate W can be plated. The plating solution usually contains components that are decomposed or deteriorated by oxidation, but in the storage tank 32, the space above the plating solution is covered with nitrogen gas, and the plating solution is isolated from oxygen. The above components do not oxidize because they are dripping.

[0006]

However, when the plating solution flows down through the reflux pipe, it is mixed with air, and the components that are easily oxidized are oxidized. This is because the inner diameter of the reflux pipe 34 is designed to be large so that the plating solution flowing from the recovery tank 35 can flow at a sufficient flow rate, so that the inside of the reflux pipe 34 is liquid-tight when the plating solution flows. This is because the air is present. As a result, the plating solution deteriorates in a short time and does not have the desired characteristics. When the plating solution flows into the storage tank 32, air bubbles may be entrained and the plating solution in the storage tank 32 may deteriorate.

Therefore, an object of the present invention is to provide a plating apparatus in which the plating solution is less likely to deteriorate.

[0008]

[Means for Solving the Problems and Effects of the Invention] The invention according to claim 1 for solving the above problems is a plating tank (1) for plating a treatment object (W), and the above plating. An accommodating tank (2) arranged at a position lower than the tank and accommodating a plating solution, a first pipe (3) for feeding the plating solution from the accommodating tank to the plating tank, and Second pipes (4, 8) for feeding the plating solution to the storage tank, and pumping means (6) for pumping the plating solution from the storage tank to the plating tank via the first pipe. And a buffer tank (7) interposed in the second pipe and disposed at a height between the plating tank and the storage tank.
A liquid level sensor (10) for obtaining information on the liquid level height of the plating solution in the buffer tank, and a valve (in the second pipe, interposed between the buffer tank and the containing tank ( 13) and a valve control means (14) for controlling the opening and closing of the valve based on the output signal of the liquid level sensor.

The alphanumeric characters in parentheses represent corresponding components in the embodiments described later. The same applies in this section below. The valve control means can control the valve so that the plating solution in the buffer tank is not exhausted and the buffer tank is not completely filled with the plating solution. In such a case, the second pipe located at a position lower than the buffer tank is filled with the plating solution. Therefore, when the plating solution flows down through the second pipe, the components that are easily oxidized in the plating solution are not mixed with air and oxidized. That is, by using such a plating apparatus, the plating solution is less likely to deteriorate.

It is preferable that the buffer tank is arranged so that there is no difference in height from the plating tank as much as possible. This makes it possible to prevent air from entering the plating solution when the plating solution flows down from the plating tank to the buffer tank. According to a second aspect of the present invention, the liquid level sensor is a first liquid level sensor (10a) for detecting the presence or absence of a plating solution at a height of a first level, and a second level higher than the first level. Including a second liquid level sensor (10b) for detecting the presence or absence of the plating solution at the height of the first level, and the valve control means has the first level indicating that there is no plating solution at the first level.
The valve is controlled to be closed based on the output signal from the liquid level sensor, and the valve is controlled to be opened based on the output signal from the second liquid level sensor indicating that the plating solution is at the second level. The plating apparatus according to claim 1, wherein:

When the first liquid level sensor does not detect the plating liquid, the liquid level of the plating liquid is lower than the first level.
When the second liquid level sensor is detecting the plating solution,
The level of the plating solution is higher than the second level. Therefore, the height of the liquid level of the plating solution is maintained between the first level and the second level in the buffer tank by the valve control means performing the above control. At this time, the second pipe is filled with the plating solution.
The second pipe may have an inner diameter that allows the plating solution to flow at a sufficient flow rate so that the level of the plating solution in the buffer tank is lowered when the valve is opened.

The invention according to claim 3 further comprises an overflow pipe (11) having one end connected to a predetermined height of the buffer tank and the other end connected to the storage tank. The plating apparatus according to Item 1 or 2. The overflow pipe can be connected to, for example, the upper side surface of the buffer tank. Claim 2
As described, when the liquid level sensor can detect the presence or absence of the plating solution at the first level and the second level, the overflow pipe can be connected to the buffer tank at a position higher than the second level. .

When the level of the plating solution in the buffer tank rises and reaches the height at which the overflow pipe is attached, the plating solution overflows from the overflow pipe and flows into the storage tank. Therefore, due to a failure of the liquid level sensor, correct information regarding the liquid level of the plating solution in the buffer tank is not given to the valve control means, and even if the valve is not opened, the plating solution will not overflow from the buffer tank or the like. Absent. The invention according to claim 4 further comprises a recovery tank (5) which is arranged around the plating tank and recovers the plating solution overflowing from the plating tank, wherein the second pipe is the recovery tank and the buffer tank. The plating apparatus according to any one of claims 1 to 3, further comprising a pipe (8) for connecting to and.

By supplying the plating solution from below the plating tank,
When the plating solution overflows from the edge of the plating tank to the recovery tank, the plating solution is slightly raised from the edge of the plating tank. The object to be processed can be brought into contact with the liquid surface of the plating solution in such a state, and for example, only one surface of a plate-shaped object to be processed such as a semiconductor substrate can be plated. The invention according to claim 5 further comprises an inert gas introducing means (15, 16) for introducing an inert gas into the storage tank, wherein the plating according to any one of claims 1 to 4. It is a device.

The inert gas introduction means includes, for example, an inert gas introduction pipe for introducing the inert gas from the supply source of the inert gas into the storage tank, and a leak pipe for leaking the gas in the storage tank. be able to. The storage tank is
It may be closed except for the part to which the pipe is connected. In this case, for example, an inert gas such as nitrogen gas is introduced from the inert gas introduction pipe and the internal gas is leaked from the leak pipe, whereby the space above the plating solution is replaced (purged) with nitrogen gas. . In this state, the surface of the plating solution is cut off from oxygen, so that the plating solution can be prevented from being oxidized.

When this plating apparatus is provided with an overflow pipe, the inert gas is also introduced into the buffer tank through the overflow pipe. If the space above the plating solution in the buffer tank is replaced with an inert gas, it is possible to prevent the plating solution from oxidizing even in the buffer tank.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, referring to the accompanying drawings,
Embodiments of the present invention will be described in detail. Figure 1
1 is a schematic sectional view of a plating apparatus according to an embodiment of the present invention. This plating apparatus is for performing a plating process on one surface of the semiconductor substrate W, and is arranged so as to surround the plating tank 1 and a plating tank 1 for supplying a plating solution to the lower surface of the semiconductor substrate W. A recovery tank 5 and a plating tank 1 and a storage tank 2 arranged at a position lower than the recovery tank 5 and capable of storing a large amount of plating solution are provided. Plating tank 1
Has an open top so that the semiconductor substrate W to be processed can come into contact with the liquid from above. The upper portion of the recovery tank 5 is open so that the plating solution overflowing from the plating tank 1 can flow into it. The upper part of the storage tank 2 is closed by a top plate 2a.

The lower part of the side surface of the storage tank 2 and the central part of the bottom surface of the plating tank 1 are connected by a pumping pipe 3. A pump 6 is interposed in the pumping liquid pipe 3 so that the plating solution in the storage tank 2 can be pumped up to the plating tank 1. Below the recovery tank 5, a buffer tank 7 is arranged close to the recovery tank 5. The upper portion of the buffer tank 7 is covered with a top plate 7a. From the bottom surface of the recovery tank 5, a reflux pipe 8 penetrates the top plate 7 a and extends to the lower portion inside the buffer tank 7. A leak pipe 9 extends upward from the top plate 7a. The leak pipe 9 penetrates the bottom surface of the recovery tank 5 and has an upper end open to the inside of the recovery tank 5.

Further, from the buffer tank 7, the reflux pipe 4
And the overflow pipe 11 extends to the storage tank 2. The reflux pipe 4 extends from the bottom surface of the buffer tank 7,
It penetrates through the top plate 2a and extends to the lower part inside the storage tank 2. The inner diameter of the reflux pipe 4 is adjusted by the pump 6 to the plating tank 1
It is designed to be large enough so that the plating solution can be flowed at a flow rate equal to or higher than the flow rate of the plating solution sent to. A valve 13 is provided in the middle of the reflux pipe 4 so that the flow path of the plating solution can be opened and closed. The overflow pipe 11 extends from the upper portion of the side surface of the buffer tank 7, penetrates the top plate 2 a, and extends to the upper portion in the storage tank 2.

A nitrogen gas introducing pipe 15 and a leak pipe 16 are introduced into the container 2 through the top plate 2a. The nitrogen gas introduction pipe 15 is connected to the nitrogen gas supply source outside the storage tank 2, and opens inside the storage tank 2 near the top plate 2 a. One end of the leak pipe 16 is open to the outside of the storage tank 2, and the other end is open in the storage tank 2 near the top plate 2 a. A liquid surface sensor 10 for detecting the liquid surface of the plating liquid inside the buffer tank 7 is disposed on the side of the buffer tank 7. The liquid level sensor 10 includes two liquid level sensors arranged vertically, that is, a lower limit liquid level sensor 10a arranged below and an upper limit liquid level sensor 10b arranged above.

The lower limit liquid level sensor 10a can detect whether or not the plating solution in the buffer tank 7 is at the height (first level) where the lower limit liquid level sensor 10a is arranged.
The upper limit liquid level sensor 10b can detect whether or not the plating solution in the buffer tank 7 is at the height (second level) where the upper limit liquid level sensor 10b is arranged. The lower limit liquid level sensor 10a and the upper limit liquid level sensor 10b are, for example,
The plating solution in the buffer tank 7 can be optically detected. In this case, the side surface of the buffer tank 7 can be made of a transparent material.

The upper limit liquid level sensor 10b is arranged at a position lower than the connecting portion between the overflow pipe 11 and the buffer tank 7. That is, the overflow pipe 11 is
It is connected to the buffer tank 7 at a position higher than the second level. Lower limit liquid level sensor 10a and upper limit liquid level sensor 10b
The output signal of is input to the control unit 14. Control unit 14
Is the lower limit liquid level sensor 10a and the upper limit liquid level sensor 10b.
The opening / closing of the valve 13 is controlled based on the output signal of
Specifically, when the control unit 14 receives a signal indicating that there is no plating solution at the first level from the lower limit liquid level sensor 10a, the control unit 14 controls to close the valve 13. In addition, the control unit 14
Receives a signal indicating that the plating liquid is at the second level from the upper limit liquid level sensor 10b, and controls the valve 13 to open. That is, the control unit 14 controls the valve 13 when the liquid level of the plating solution in the buffer tank 7 becomes lower than the first level.
Is controlled to open, and the valve 13 is controlled to be closed when the level becomes higher than the second level.

Prior to the plating process, first, nitrogen gas is introduced into the storage tank 2 from the nitrogen gas introduction pipe 15. The gas in the storage tank 2 is leaked to the outside from the leak pipe 16 or overflow gas 11 and the buffer tank 7
And leaks to the outside through the leak pipe 9. When this operation is continued for a certain period of time or more, the space above the plating solution inside the storage tank 2 and the inside of the buffer tank 7 are replaced (purged) with nitrogen gas. As a result, it is possible to prevent the oxidizable component contained in the plating solution in the storage tank 2 from being oxidized.

Next, when the pump 6 is operated, the plating solution is pumped from the storage tank 2 to the plating tank 1 through the pumping pipe 3 and overflows from the edge of the plating tank 1 to the recovery tank 5.
In the plating tank 1, since the plating solution flows from the lower side to the upper side, the liquid level of the plating solution is slightly raised from the edge of the plating tank 1. One surface of the semiconductor substrate W can be plated by bringing the lower surface of the semiconductor substrate W into contact with the raised plating solution to perform plating.

The plating solution further flows from the bottom of the recovery tank 5 into the buffer tank 7 through the reflux pipe 8. Buffer tank 7
Since the inner space communicates with the outside through the leak pipe 9, it is always kept at atmospheric pressure. Therefore, the plating solution can freely flow into the buffer tank 7. Since the inside of the buffer tank 7 is kept in the nitrogen atmosphere, the components of the plating solution that are easily oxidized are not oxidized in the buffer tank 7. The height of the level of the plating solution in the buffer tank 7 is the second
When the level is below the level, the valve 13 is closed, for example, and the plating solution is stored in the buffer tank 7 and the liquid level rises. When the height of the plating liquid becomes higher than the second level, the valve 13 is opened by the control unit 14, and the plating liquid passes through the reflux pipe 4 by the action of gravity and enters the storage tank 2
Flows into. When the liquid level of the plating solution becomes lower than the first level, the control unit 14 closes the valve 13 and the plating solution is stored again in the buffer tank 7.

As described above, by controlling the liquid level of the plating solution in the buffer tank 7 so as to be substantially between the first level and the second level, it is arranged at a position lower than the buffer tank 7. The inside of the reflux pipe 4 is always filled with the plating solution (liquid tightness). Therefore, even when the oxygen partial pressure of the gas existing in the buffer tank 7 is not sufficiently low, the plating solution is not mixed with air when flowing in the reflux pipe 4, so that the plating solution is oxidized. Easy components are not oxidized. That is, by using such a plating apparatus, the plating solution is less likely to deteriorate.

When the upper limit liquid level sensor 10b fails, the upper limit liquid level sensor 10b indicates that the plating liquid is at the second level even if the liquid level of the plating liquid in the buffer tank 7 becomes higher than the second level. The output signal may not be output. In this case, the control unit 14 does not control to open the valve 13,
The plating solution in the buffer tank 7 becomes higher than the second level. However, when the level of the plating solution reaches the height of the connecting portion between the buffer tank 7 and the overflow pipe 11, the plating solution flows out from the overflow pipe 11 and the storage tank 2
Be led to. Therefore, the plating solution does not fill the buffer tank 7 and the liquid level does not further rise to overflow the recovery tank 5.

When the liquid level sensor 10 optically detects the plating solution in the buffer tank 7 made of a transparent material, even if the upper limit liquid level sensor 10b is not defective, The presence or absence of the plating solution at the second level cannot be correctly detected due to the contamination of the side wall. Even in such a case, the valve 13 will not be opened and closed properly, but it is possible to prevent the plating solution from overflowing from the recovery tank 5 by flowing out the plating solution from the overflow pipe 11.

The liquid level sensor 10 may be capable of detecting the liquid level height of the plating solution in the buffer tank 7 as a continuous value. In that case, the control unit 14 may continuously change the opening degree of the valve 13 and continuously change the flow rate of the plating solution flowing through the reflux pipe 4. The plating treatment in the plating tank 1 is not limited to the one in which the object to be treated is brought into contact with the surface of the plating solution, and the entire object to be treated may be immersed in the plating tank 1 to perform the plating treatment. In this case, the recovery tank 5 may be omitted.

Besides, various modifications can be made within the scope of the matters described in the claims.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a plating apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view of a conventional plating apparatus for performing a plating process on a semiconductor substrate.

[Explanation of symbols]

1 plating tank 2 storage tanks 3 Lifting piping 4,8 Return piping 5 collection tanks 6 pumps 7 buffer tanks 10a Lower limit liquid level sensor 10b Upper limit liquid level sensor 11 Overflow piping 13 valves 14 Control unit 15 Nitrogen gas introduction piping 16 leak piping

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Ryuichi Hanyama             4 Horikawa-dori Teranouchi, Kamigyo-ku, Kyoto City, Kyoto Prefecture             No. 1 at Tenjin Kitamachi             Manufacturing Co., Ltd. F term (reference) 4K022 DA01 DB13 DB18 DB20                 4K024 BB12 CB01 CB12 CB15

Claims (5)

[Claims] 1. A plating tank for plating an object to be treated, a storage tank arranged at a position lower than the plating tank for storing a plating solution, and a plating solution sent from the storage tank to the plating tank. A second pipe for feeding a plating solution from the plating tank to the storage tank, and a plating from the storage tank to the plating tank via the first pipe A pumping means for pumping the liquid, a buffer tank interposed in the second pipe and arranged at a height between the plating tank and the storage tank, and a liquid level height of the plating solution in the buffer tank. Level sensor for obtaining information regarding the level, a valve interposed between the buffer tank and the storage tank in the second pipe, and opening / closing of the valve is controlled based on an output signal of the liquid level sensor. And valve control means for controlling Plating apparatus to be. 2. A liquid level sensor for detecting the presence or absence of a plating liquid at a height of a first level, and a plating liquid at a height of a second level higher than the first level. A second liquid level sensor for detecting the presence or absence of the liquid, and the valve control means controls to close the valve based on an output signal from the first liquid level sensor indicating that there is no plating liquid at the first level. The plating apparatus according to claim 1, wherein the valve is controlled to open based on an output signal from the second liquid level sensor indicating that the plating liquid is present at the second level. 3. The plating apparatus according to claim 1, further comprising an overflow pipe having one end connected to a predetermined height of the buffer tank and the other end connected to the storage tank. 4. A recovery tank disposed around the plating tank for collecting the plating solution overflowing from the plating tank, wherein the second pipe is a pipe connecting the recovery tank and the buffer tank. 4. The method according to claim 1 or 2, further comprising:
The plating apparatus according to any one of 1. 5. The plating apparatus according to claim 1, further comprising an inert gas introducing means for introducing an inert gas into the storage tank.