JP5458604B2 - Sn alloy plating apparatus and its Sn component replenishment method - Google Patents

Description

  The present invention relates to a plating apparatus for forming a Sn alloy plating film on a substrate to be processed, and a method for supplying Sn component thereof.

  In the plating apparatus, it is necessary to replenish the metal component in order to keep the concentration of the metal component in the plating solution constant. In the inventions disclosed in Patent Documents 1 to 3, a replenisher solution (element solution) of a component of the plating solution is stored in a replenisher tank, and the replenisher solution is supplied from the replenisher tank based on the analysis result of the component concentration of the plating solution I try to replenish it inside.

JP 2003-183898 A JP 2001-73200 A JP-A-6-264251

In recent years, Sn-Ag plating solution is used as an alternative to Pb-Sn alloy plating solution which has been widely used for plating on electronic parts that require soldering and forming solder bump electrodes (bumps) on semiconductor wafers. It is getting to be.
In this Sn-Ag plating solution, the element solution such as a tin salt solution in which its essential components are dissolved is added to replenish Sn ²⁺ , so that a large amount of the element solution is required. It is cumbersome and expensive.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a plating apparatus capable of easily managing a plating solution and replenishing a Sn alloy plating solution with a simple method at a low cost, and a Sn component replenishing method thereof. There is to do.

In the Sn alloy plating apparatus of the present invention, the substrate to be processed is brought into contact with the plating solution of Sn alloy stored in the plating tank, and the Sn alloy is applied to the substrate to be processed by energization between the substrate to be processed and the electrode. in the plating apparatus for forming a plating film, the a tank for storing the plating solution is circulated between the plating tank, the plating supplies the pumping article al before Symbol plating tank and pump the plating solution in the tank which has a liquid supply means, to a downstream position than the pump of the plating solution supply means, be provided with a supply means for supplying the powder of the stannous oxide to the plating solution flowing, said feeding means, said A bypass pipe provided in parallel with the plating solution supply pipe in the plating solution supply means; a control means for controlling the flow of the plating solution passing through the bypass pipe; and the stannous oxide powder is placed in the middle of the bypass pipe. Quantitative A metering mechanism for feeding, characterized by comprising the said bypass tube fluid can be discharged a drain mechanism.

That is, the Sn alloy component is replenished by supplying the stannous oxide powder to the plating solution, so that it is not necessary to prepare a large amount of elemental solution as in the prior art, and its management is facilitated. In this case, the stannous oxide powder is supplied to the downstream position of the pump of the plating solution supply means, and the stannous oxide powder is directly supplied into the flow of the plating solution fed by the pump. It will be. Therefore, stannous oxide dissolves quickly in the plating solution, and it is dispersed in the plating tank in a short time by riding on the flow of the plating solution without adding a special device for stirring, so that it can be replenished uniformly. Can do.

In addition, normally, when the plating solution is circulated through the plating solution supply pipe, the bypass pipe is left empty, and the powder of stannous oxide is replenished, the powder is supplied from the quantitative supply mechanism into the bypass pipe. After supplying a predetermined amount, the control means makes it possible to circulate the plating solution into the bypass pipe, and the plating solution sent by the pump circulates while flowing the powder in the bypass pipe. At that time, the powder of stannous oxide is It quickly dissolves in the plating solution and is supplied to the plating tank.

And the method of replenishing the Sn alloy component to the plating solution is characterized in that the stannous oxide powder is supplied to the downstream position of the pump while circulating the plating solution between the plating tank and the tank. And
Powder can be replenished while stirring the plating solution by circulating the plating solution between the tank and the plating tank.

  According to the plating apparatus of the present invention, the Sn alloy component is replenished by supplying the stannous oxide powder to the plating solution. Will also be easier. Moreover, in that case, the powder is directly supplied to the flow of the plating solution sent from the tank to the plating tank, and a special device for stirring the plating solution is not necessary, so that it can be implemented at a low cost.

BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic block diagram which made the longitudinal cross-section part which shows 1st Embodiment of the plating apparatus which concerns on this invention. It is a schematic block diagram of the replenishment mechanism in the plating apparatus of FIG. It is the schematic block diagram which made the longitudinal cross-section part which shows 2nd Embodiment of the plating apparatus which concerns on this invention.

Hereinafter, embodiments of a plating apparatus and a replenishing method thereof according to the present invention will be described with reference to the drawings.
1 and 2 show a first embodiment in which the present invention is applied to a jet-type plating apparatus. A plating apparatus 100 according to this embodiment includes a plating tank 1 in which a plating solution is stored, and a plating tank 1. A substrate support 3 provided at the upper end of the gantry 2 provided on the outer side and disposing a wafer to be processed S in the upper opening of the plating tank 1; and the processing of the upper part of the plating tank 1 from the bottom of the plating tank 1 A plating solution supply means 4 for supplying a plating solution toward the substrate S, a plating solution discharge means 5 for discharging the plating solution from the plating tank 1 to the outside while overflowing, and supplying a powder of stannous oxide to the plating solution Supply means 6.

The substrate support unit 3 is provided with a cathode electrode 11 that is in contact with the substrate S to be processed, and the substrate S to be processed is connected to an external power source 12 and is slightly raised from the upper opening of the plating tank 1. The substrate to be processed S is supported at this position, so that the surface to be plated of the substrate to be processed S can be held in contact with the surface of the plating solution overflowing from the upper opening. Reference numeral 13 in FIG. 1 denotes a weight that contacts the upper surface of the substrate S to be processed.
On the other hand, an anode electrode 14 is provided inside the plating tank 1 with a space below the substrate S to be processed. The anode electrode 14 is a conductor formed in a mesh shape, for example, and is horizontally attached to the electrode support portion 15 in the plating tank 1. For example, a plurality of electrode support portions 15 are provided on the inner peripheral surface of the plating tank 1 at intervals in the circumferential direction.

  The plating solution supply means 4 includes an ejection nozzle 21 that ejects the plating solution vertically upward from the center position of the bottom of the plating tank 1, and a plating solution supply unit 22 that supplies the plating solution to the ejection nozzle 21. It is configured. The plating solution supply unit 22 is provided in the middle of the tank 23 for storing the plating solution, a plating solution supply pipe 24 for supplying the plating solution in the tank 23 to the ejection nozzle 21, and the plating solution supply pipe 24. The pump 25 is provided. A replenishing means 6 is provided at a position downstream of the pump 25 in the plating solution supply pipe 24.

  That is, as shown in FIG. 2, the plating solution supply pipe 24 connected to the pump 25 is provided with a bypass pipe 31 that branches from the middle and reaches the plating solution supply pipe 24 again. Switching valves (control means) 32 and 33 that can selectively switch the flow path to either the plating solution supply pipe 24 or the bypass pipe 31 are disposed at the branch connection portion. In this case, the plating solution supply pipe 24 is provided along the vertical direction, and the bypass pipe 31 is also provided along the vertical direction parallel to the plating solution supply pipe 24. A shutter 34 that can be opened and closed is provided in the middle of the bypass pipe 31 so as to divide the bypass pipe 31 into two vertically, and a space defined above the shutter 34 is defined as a powder supply chamber 35. A fixed quantity supply mechanism 36 for supplying a predetermined amount of stannous oxide powder is connected to the powder supply chamber 35.

The fixed amount supply mechanism 36 stores a powder and discharges it little by little from the lower feeder 37, a weighing transfer machine 39 that receives, measures and conveys the powder discharged from the hopper 38, and a weighing transfer machine 39. And a transfer machine 40 for transferring the powder conveyed from the inside of the powder into the powder supply chamber 35 of the bypass pipe 31.
The weighing and conveying machine 39 is provided with a weighing device 42 on the conveyor 41, and the powder received from the hopper 38 is measured by the weighing device 42 and then conveyed by the conveyor 42.
In the example of FIG. 2, the transfer device 40 is configured by an extruder, and receives the powder transported from the metering transport device 39 in the cylinder 43 and pushes it forward by the piston 44. In this case, an inclined shooter 45 is connected to the tip of the cylinder 43, and the shooter 45 is connected to the powder supply chamber 35 of the bypass pipe 31. Further, shutters 46 and 47 for opening and closing between the cylinder 43 and the shooter 45 and between the shooter 45 and the chamber 35 are provided, respectively.

The quantitative supply mechanism 36 calculates based on the analyzer 52 that samples the plating solution in the tank 23 by the pump 51 and measures the Sn component concentration, the analysis result of the analyzer 52, and the measurement result of the measuring instrument 42. A control unit 53 that controls the feeder 37 is connected to drop the necessary replenishment amount of powder from the hopper 38.
A drain mechanism 54 is provided in the powder supply chamber 35 of the bypass pipe 31. The drain mechanism 54 includes a drain pipe 55 connected to the chamber 35 and a valve 56 that opens and closes the flow path.

  On the other hand, the plating solution discharge means 5 surrounds the plating outflow path 61 formed between the substrate S to be processed supported by the substrate support unit 3 and the upper opening of the plating bath 1 and the plating bath 1. The outer tank 62 is provided and a liquid recovery pipe 63 that connects the inside of the outer tank 62 to the tank 23 of the liquid supply means 4. The plating solution in the plating tank 1 overflows from the liquid outflow path 61. The plating solution received in the outer tank 62 can be recovered in the tank 23 of the liquid supply means 4 via the liquid recovery pipe 63.

  In the plating apparatus 100 configured as described above, the plating solution supplied from the plating solution supply means 4 is applied to the surface of the substrate S to be processed while supplying current from the power source 12 to the cathode electrode 11 and the anode electrode 14. By spraying and making contact, a plating process is performed on the plating surface of the substrate S to be processed. As a wafer to be processed substrate S supported by the substrate support unit 3, a silicon wafer on which a resist pattern is formed in advance is used, and plating is performed on the silicon wafer in the resist pattern opening.

  Moreover, Sn—Ag alloy plating solution or the like is used as the plating solution, and the plating solution ejected from the ejection nozzle 21 rises as an upward flow at the center of the plating tank 1 as shown by the arrow in FIG. After the contact with the central portion of the surface to be processed of the substrate S to be processed, the liquid spreads radially outward along the surface to be plated and convects in the plating tank 1 while the liquid in the upper opening of the plating tank 1 is partially Overflow from the discharge path 61. The plating solution overflowed from the plating tank 1 is recovered from the outer tank 62 to the tank 23 via the liquid recovery pipe 63. The plating solution stored in the tank 23 is ejected from the ejection nozzle 21 into the plating tank 1 through the plating solution supply pipe 24 by the pump 25.

  In this way, the plating solution in the plating tank 1 and the plating solution in the tank 23 are circulated and are subjected to the plating treatment in the plating tank 1. Further, the plating solution in the tank 23 is sampled by the analyzer 52 and analyzed for the component concentration. When the Sn component concentration is lowered, the powder of stannous oxide is supplied from the supply means 6.

A method for supplying the stannous oxide will be described.
In the bypass pipe 31 provided in parallel with the plating solution supply pipe 24, the upper and lower switching valves 32, 33 normally allow the plating solution to flow only through the plating solution supply pipe 24, and the chamber 35 of the bypass pipe 31. The interior is empty. Prior to the replenishment of the powder, a dummy substrate such as a glass plate is supported on the substrate support portion 3 of the plating tank 1.
Based on the analysis result of the analyzer 52, the required amount of powder replenished is calculated in the control unit 53, and the corresponding amount of powder is discharged from the hopper 38 to the weighing and conveying machine 39 by the feeder 37. In the weighing and conveying machine 39, the received powder is weighed, the weighing result and the necessary replenishment amount are compared by the control unit 53, and the feeder 37 is driven until the weighing result matches the necessary replenishment amount.
When the powder received by the weighing and conveying machine 39 reaches the required replenishment amount, the conveyor 41 puts the powder into the cylinder 43 of the transfer mechanism 40 and opens the shutter 46 in front of the cylinder 43 to transfer the powder to the shooter 45. To do.

Next, after closing the shutter 46 between the shooter 45 and the cylinder 43, when the shutter 47 in front of the shooter 45 is opened, the powder in the shooter 45 falls into the chamber 35 of the bypass pipe 31. Then, the shutter 47 at the outlet of the shooter 45 is closed, the shutter 34 at the lower end of the chamber 35, that is, the upstream position of the chamber 35 is opened, and both the switching valves 32 and 33 are switched to The distribution of the plating solution is stopped and the plating solution is circulated through the bypass pipe 31. By this switching operation, the powder supplied into the bypass pipe 31 is pushed away while being dissolved in the plating solution, and ejected from the ejection nozzle 21 into the plating tank 1.
The bypass pipe 31 need only be opened for a short time during which the internal powder is swept away. After the plating solution is circulated for a predetermined time, the switching valves 32 and 33 are switched to distribute the plating solution to the plating solution supply pipe 24. And circulate between the plating tank 1 and the tank 23.
After switching the plating solution flow to the plating solution supply pipe 24, the plating solution remaining in the bypass pipe 31 is discharged by the drain mechanism 54, and the chamber 35 is left empty for the next replenishment. .

In this way, the powder is rapidly dissolved in the plating solution by supplying the powder to the plating solution fed by the pump 25 and circulating the plating solution between the tank 23 and the plating tank 1. And evenly distributed throughout. Therefore, the replenishment work can be performed in a short time. Moreover, it is a simple method of supplying powder in piping (bypass pipe 31), and management as powder is also easy. Moreover, as a means for stirring, the jet stream from the jet nozzle 21 used for normal plating processing and the circulation between the tank 23 and the plating tank 1 are used, and it is necessary to provide a special stirring device. And can be implemented at low cost.
Since the Sn—Ag plating solution has Sn ²⁺ of 97 to 99 wt%, Ag ^{+ of 1} to 3 wt%, and most of it is Sn, the replenishment method using this powder is extremely effective. The stannous oxide powder is used in an amount of, for example, 2 to 3 g per 1 liter of the acidic plating solution, and 400 to 600 g for a 200 liter acidic plating solution. 100 to 200 substrates can be plated with the plating solution.

To supplement the explanation of the supplied stannous oxide powder, the average particle diameter is in the range of 10 to 20 μm in D50 value, and the tap density is 0.6 to 1.2 g / cm ³ . It is preferable to use tin powder. Moreover, it is preferable that a specific surface area is the range of 7-10 m < ² > / g. This is because a stannous oxide powder having an average particle diameter and a tap density within the above ranges has extremely high solubility in an acid or acidic plating solution, that is, is easily soluble in an acid or acidic plating solution. Specifically, this stannous oxide powder has a dissolution rate that dissolves within 5 seconds when 20 g of stannous oxide powder is added to 300 ml of an alkanesulfonic acid aqueous solution at a temperature of 25 ° C. and stirred.

  In addition, the average particle diameter prescribed | regulated by D50 value means a particle diameter when the accumulation particle volume with respect to all the particle volumes will be 50% when particle distribution is measured. Examples of the acid having excellent solubility include alkane sulfonic acids such as methane sulfonic acid, ethane sulfonic acid, and 1-propane sulfonic acid, which are components of the acidic plating solution. In addition to the Sn-Ag alloy plating solution described above, which is an Sn alloy plating solution composed of noble elements from Sn and Sn, the acidic plating solution includes Sn-Cu alloy plating solution and Sn-Ag-Cu alloy plating solution. Or Au-Sn alloy plating solution etc. are mentioned.

When producing this stannous oxide powder, first, an aqueous acid solution is prepared by dissolving a metal Sn powder in an acid. As the acid, hydrochloric acid is preferable, and the metal Sn powder used preferably has an α-ray emission amount of 0.05 cph / cm ² or less. Next, an alkaline aqueous solution is added to the prepared acidic aqueous solution, and the mixture is stirred and neutralized to prepare a stannous hydroxide slurry. Examples of the alkaline aqueous solution include aqueous ammonia, ammonium bicarbonate solution, or a mixture thereof. The neutralization step for preparing the stannous hydroxide slurry is performed in a nitrogen gas atmosphere. This neutralization reaction is preferably performed at a reaction solution temperature of 30 to 50 ° C. and a pH of 6 to 8.

Next, the prepared slurry is heated and held to age and dehydrate the stannous hydroxide to obtain a stannous oxide slurry. This dehydration step is performed in a nitrogen gas atmosphere. The heating and holding temperature is preferably 80 to 100 ° C. Further, the above stannous oxide slurry is filtered, and the resulting stannous oxide precipitate is washed with water and then dried by vacuum drying. The temperature during vacuum drying is preferably 40 to 100 ° C.
By passing through the above steps, an acid or acidic plating solution having an average particle diameter of 10 to ²⁰ μm in D50 value, a specific surface area of 7 to 10 m ² / g, and a tap density of 0.6 to 1.2 g / cm ^3. A stannous oxide powder having a very high solubility in is produced.

In the first embodiment, the present invention is applied to the jet plating apparatus, but may be applied to an immersion plating apparatus as shown in FIG. In the plating apparatus 200 according to the second embodiment, the substrate to be processed S and the anode electrode 72 are immersed in the plating solution in the plating tank 71 and connected to the external power source 12. Then, the plating solution ejected from the ejection nozzle 21 at the bottom of the plating tank 71 is caused to overflow from the upper part of the plating tank 71 to conduct current between the substrate S to be processed and the anode electrode 72 to perform the plating process. In addition, a tank 23 for storing a plating solution circulated between the plating tank 71 and a plating solution supply means 4 for supplying the plating solution from the tank 23 to the ejection nozzle 21 is provided at a position downstream of the pump 25. A replenishment mechanism 6 is provided as in the case of the first embodiment. In addition, the same code | symbol is attached | subjected to the component similar to 1st Embodiment, and description is abbreviate | omitted.
Also in this plating apparatus 200, an Sn—Ag alloy plating solution or the like is used as a plating solution, and the plating solution supply means 4 supplies the stannous oxide powder while circulating the plating solution between the plating tank 71 and the tank 23. By supplying to a position downstream of the pump 25, Sn component can be replenished.

As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the concrete structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the summary of this invention are included.
For example, in the embodiment, a switching valve is provided at the branch connection portion between the plating solution supply pipe and the bypass pipe, and when supplying powder, the flow of the plating solution to the plating solution supply pipe is stopped and the bypass pipe is connected. However, by providing a control valve only at both ends of the bypass pipe away from the branch connection portion, and opening and closing the control valve of the bypass pipe while circulating the plating solution to the plating solution supply pipe, It is good also as a structure which distribute | circulates a part of plating solution also to a bypass pipe and supplies powder. As in the embodiment, the control means of the present invention is configured so that the plating solution supply pipe is always in a circulation state and the bypass pipe is circulated as necessary, in addition to the switching valve that selectively switches the flow path to any one of them. Shall also be included.
Moreover, although the weight of the powder was measured as the replenishment amount of the powder, a volume corresponding to the weight may be measured.
The plating solution remaining in the bypass pipe after replenishing the powder is discharged by the drain mechanism as described above. However, the plating solution discharged by the drain mechanism may be collected in the tank 23.
In addition, a liquid outflow path for overflowing the plating solution was formed between the upper opening of the plating tank and the substrate to be processed, but a through-hole or notch was provided at the upper end of the plating tank, and this flowed out. A road may be used. In the first embodiment, the electrode support part for supporting the anode electrode may also be formed in the same mesh shape as the anode electrode, and formed on the entire inner peripheral surface of the plating tank.

DESCRIPTION OF SYMBOLS 1 Plating tank 3 Substrate support part 4 Plating solution supply means 5 Plating solution discharge means 6 Supply means 11 Cathode electrode 12 Power supply 14 Anode electrode 15 Electrode support part 21 Jet nozzle 22 Liquid supply part 23 Tank 24 Plating liquid supply pipe 25 Pump 31 Bypass Pipe 32, 33 Switching valve (control means)
34 Shutter 35 Powder supply chamber 36 Fixed supply mechanism 37 Feeder 38 Hopper 39 Weighing and transporting machine 40 Transfer machine 41 Conveyor 42 Weighing instrument 43 Cylinder 44 Piston 45 Shuter 46, 47 Shutter 51 Pump 52 Analyzer 53 Control part 54 Drain mechanism 61 Liquid outflow Path 62 Outer tank 63 Liquid recovery pipe 71 Plating tank 72 Anode electrode 100 Plating apparatus 200 Plating apparatus S Substrate

Claims (2)

In a plating apparatus in which a substrate to be processed is brought into contact with a plating solution of Sn alloy stored in a plating tank, and an Sn alloy plating film is formed on the substrate to be processed by energization between the substrate to be processed and an electrode. And a tank for storing the plating solution circulated between the plating tank and a plating solution supply means for supplying the plating solution in the tank to the plating tank while pumping the plating solution. A replenishing means for supplying stannous oxide powder into the flowing plating solution is provided at a position downstream of the pump of the means ,
The replenishing means includes a bypass pipe provided in parallel to the plating solution supply pipe in the plating solution supply means, a control means for controlling the flow of the plating solution passing through the bypass pipe, and the oxidation solution in the middle of the bypass pipe. An Sn alloy plating apparatus , comprising: a fixed amount supply mechanism for supplying a predetermined amount of stannous powder; and a drain mechanism capable of discharging the fluid in the bypass pipe . A method for supplying Sn alloy components to the Sn alloy plating apparatus according to claim 1 , comprising:
An Sn component replenishing method for an Sn alloy plating apparatus, wherein the stannous oxide powder is supplied to a downstream position of the pump while circulating a plating solution between the plating tank and the tank.

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