JP5169376B2 - 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.

  An object of the present invention is to provide a plating apparatus that is easy to manage the plating solution and can supply the Sn component to the plating solution of the Sn alloy at a low cost by a simple method.

In the plating apparatus of the present invention, the substrate to be processed is brought into contact with the plating solution of the Sn alloy stored in the plating tank, and the Sn substrate is plated on the substrate to be processed by energization between the substrate to be processed and the electrode. A plating apparatus for forming a film, comprising: a tank that stores a plating solution that is circulated between the plating tanks; and a sprayer that sprays stannous oxide powder on the surface of the plating solution in the tank. The sprayer includes a spray box for storing the powder and spraying from below, and a moving mechanism for horizontally moving the spray box along the surface of the plating solution in the tank. .
That is, the Sn alloy component is replenished by spraying the stannous oxide powder onto 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. Moreover, it is possible to disperse and disperse evenly as a whole while moving the spraying box horizontally along the liquid level of the plating solution in the tank by the moving mechanism.

  Moreover, the plating apparatus of this invention WHEREIN: The said moving mechanism is good also as a structure which can move a spreading | diffusion box to the retreat position away from the upper direction of the said tank. During normal plating processing, etc., the spray box is kept away from the upper position of the tank so that it is not affected by the vapor from the plating solution and the powder remains in the tank. It is possible to prevent the deterioration when there is.

Furthermore, in the plating apparatus of the present invention, a hopper for storing the powder, and a powder replenishment for transferring a necessary amount of powder calculated based on the analysis result of the Sn component in the plating solution from the hopper to the spraying box It is good also as a structure provided with a mechanism.
Since the hopper is provided separately from the spraying box, the powder is stored in the hopper, and the necessary amount is transferred to the spraying box, the powder can be managed more rationally.

  And, the method of replenishing the plating with the Sn alloy component is characterized in that the stannous oxide powder is dispersed in the plating solution of the tank while circulating the plating solution between the plating tank and the tank. And The powder can be replenished while stirring the plating solution by circulating the plating solution.

  According to the plating apparatus of the present invention, Sn alloy components are replenished by spraying stannous oxide powder onto the plating solution, so that it is not necessary to prepare a large amount of component liquid as in the prior art, and its management This also facilitates implementation at a low cost.

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 liquid supply means 4 for supplying a plating solution toward the substrate S, a liquid discharge means 5 for discharging the plating liquid from the plating tank 1 to the outside while overflowing, and a plating liquid in the plating liquid storage tank 6 of the liquid supply means 4 And a spreader 7 for spraying a powder of stannous oxide.

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. A reference numeral 13 in FIG.
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 liquid supply means 4 is composed of an ejection nozzle 21 that ejects a 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. Has been. The plating solution supply unit 22 is provided in the middle of the tank 6 for storing the plating solution, a plating solution supply pipe 23 for supplying the plating solution in the tank 6 to the ejection nozzle 21, and the plating solution supply pipe 23. And a pump 24.

  The liquid discharge means 5 is provided so as to surround the liquid outflow path 25 formed between the substrate to be processed S supported by the substrate support portion 3 and the upper opening of the plating tank 1, and the periphery of the plating tank 1. The outer tank 26 and a liquid recovery pipe 27 that connects the inside of the outer tank 26 to the tank 6 of the liquid supply means 4 are configured to overflow the plating solution in the plating tank 1 from the liquid outflow path 25. The plating solution received in the outer tub 26 can be recovered in the tank 6 of the liquid supply means 4 via the liquid recovery pipe 27.

The spreader 7 stores powder and spreads the powder from below, a moving mechanism 32 that horizontally moves the spray box 31 along the surface of the plating solution in the tank 6, and an appropriate amount of powder in the spray box 31. A powder replenishing mechanism 33 for replenishing is provided.
The spreading box 31 is formed in a rectangular box shape with the upper side opened, and has a configuration in which the powder F is accommodated therein and a hole 35 for spreading is formed in the bottom plate 34.

  In the illustrated example, the moving mechanism 32 is constituted by an XY stage. As shown in FIG. 2, the moving mechanism 32 is a pair of guide rails 36 disposed along the X-axis direction at the upper end of the tank 6, and these guide rails. And a slider 37 arranged so as to be bridged between the guide rails 36, and on the slider 37, the spraying box 31 extends along the Y-axis direction orthogonal to the X-axis. It is supported movably. Further, one end portions of both guide rails 36 extend to a side position deviated from the upper side of the tank 6, and are arranged on an extension portion 36 a of the guide rail 36 as indicated by an arrow H in FIGS. 1 and 2. One end of the slider 37 is the home position of the spraying box 6.

  The powder replenishing mechanism 33 includes a hopper 41 for storing powder, a valve 42 for opening and closing the bottom of the hopper 41, a weighing machine 43 for measuring the weight of the spraying box 31 containing the powder F, and a plating solution in the tank 6. Analyzer 44 for sampling the Sn component concentration by pump 44a, and valve 42 for dropping the required replenishment amount of powder calculated based on the analysis result of analyzer 44 and the measurement result of weighing machine 43 from hopper 41. It is set as the structure provided with the control part 45 which controls. The weighing machine 43 is arranged immediately below the home position H of the spray box 31. The home box H supports the spray box 31 from below and can measure the weight of each spray box 31.

  In the plating apparatus 100 configured as described above, the plating solution supplied from the solution supply means 4 is directed toward the surface to be plated 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. Then, the plating process is performed on the surface to be plated 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.

  Further, Sn—Ag alloy plating solution or the like is used as the plating solution, and the plating solution ejected from the ejection nozzle 11 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 25. The plating solution overflowed from the plating tank 1 is recovered from the outer tank 26 to the tank 6 via the liquid recovery pipe 27. The plating solution stored in the tank 6 is ejected from the ejection nozzle 21 into the plating tank 1 through the plating solution supply pipe 23 by the pump 24.

  In this way, the plating solution in the plating tank 1 and the plating solution in the tank 6 are circulated and are subjected to the plating treatment in the plating tank 1. The plating solution in the tank 6 is sampled by the analyzer 44 and analyzed for the component concentration. When the Sn component concentration is lowered, the powder of stannous oxide is sprayed from the sprayer 7 into the tank 6. To be replenished.

  Explaining this replenishment method, the spray box 31 is retracted to the home position H that is off the upper side of the tank 6 as shown by a chain line in FIGS. Further, the plating solution is circulated between the plating tank 1 and the tank 6 during the plating process. When the plating process is completed, the plating solution in the plating tank 1 is entirely transferred into the tank 6. Then, the plating solution in the tank 6 is sampled and analyzed by the analyzer 44, and a necessary supply amount is calculated. At the same time, the weight of the spray box 31 at the home position H is measured, and the replenishment amount of the necessary powder is calculated in the control unit 45 based on the measurement result and the analysis result of the analyzer 44. It is supplied from the hopper 41 to the spraying box 31.

  Then, while moving the spraying box 31 horizontally in the XY direction along the liquid level of the tank 6 by the moving mechanism 32, the powder is dropped from the holes 35 of the spraying box 31 and is evenly distributed over the entire liquid level of the tank 6. And spray. Further, when spraying, the pump 24 is operated to circulate the plating solution between the tank 6 and the plating tank 1. The powder dispersed in the plating solution in the tank 6 is quickly dissolved in the plating solution and circulated between the plating tank 1 and stirred as a whole.

In this way, while moving the spraying box 31 of the sprayer 7 along the liquid level in the tank 6, the powder of stannous oxide is sprayed from the spraying box 31, and the plating solution is applied at the time of the spraying. By circulating between the tank 6 and the plating tank 1, the powder is quickly dissolved in the plating solution and dispersed uniformly throughout. Therefore, the replenishment work can be performed in a short time. Moreover, it is a simple method of spraying powder, and it is easy to manage as powder and can be carried out at low cost.
Since the Sn—Ag plating solution has 97 wt% Sn, 3 wt% Ag, and mostly Sn, this replenishment method by spraying 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.

Supplementing the description of the stannous oxide powder to be dispersed, the first particle size is an average particle diameter in the range of 10 to 20 μm in D50 value and a tap density of 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 of the second embodiment, the substrate to be processed S and the anode electrode 52 are immersed in the plating solution in the plating tank 51 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 51 overflows from the upper part of the plating tank 51 to conduct the plating process by energizing between the substrate S to be processed and the anode electrode 52. Further, a tank 6 for storing a plating solution circulated with the plating tank 51 is provided, and a sprayer 7 is provided in the tank 6 as in the case of the first embodiment. In addition, the same code | symbol is attached | subjected to the component similar to one Embodiment, and description is abbreviate | omitted.
Also in this plating apparatus 200, Sn—Ag alloy plating solution or the like is used as a plating solution, and stannous oxide powder is dispersed in the tank 6 while circulating the plating solution between the plating tank 51 and the tank 6. By doing so, the 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, although an example in which an XY stage is used as the moving mechanism of the spray box has been shown, a configuration in which the spray box is held at the tip of the arm of the robot and moved above the tank to an arbitrary position may be adopted. Further, a fine vibration mechanism may be provided in the spray box in order to ensure spraying. 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. A road may be used. Moreover, the electrode support part which supports an anode electrode may also be formed in the same mesh shape as an anode electrode, and may be formed in the inner peripheral surface whole periphery of a plating tank.

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 the top view which looked at the tank in the plating apparatus of FIG. 1 from upper direction. 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.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plating tank 2 Base 3 Substrate support part 4 Liquid supply means 5 Liquid discharge means 6 Tank 7 Spreader 11 Cathode electrode 12 Power supply 13 Weight 14 Anode electrode 15 Electrode support part 21 Ejection nozzle 22 Liquid supply part 23 Plating liquid supply pipe 24 Pump 25 Liquid outflow path 26 Outer tank 27 Liquid recovery pipe 31 Spray box 32 Movement mechanism 33 Powder replenishment mechanism 34 Bottom plate 35 Hole 36 Guide rail 36a Extension part 37 Slider 41 Hopper 42 Valve 43 Weighing machine 44 Analyzer 45 Control part 51 Plating tank 52 Anode electrode 100 Plating apparatus 200 Plating apparatus S Substrate H Home position

Claims (4)

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. ,
A tank for storing a plating solution circulated between the plating tank and a sprayer for spraying stannous oxide powder on the surface of the plating solution in the tank ;
The sprayer includes a spray box that stores the powder and sprays from below, and a moving mechanism that horizontally moves the spray box along the surface of the plating solution in the tank. Plating equipment. The moving mechanism, the plating apparatus according to claim 1, wherein the up retracted position away from above the tank is movable spray box. A hopper for storing the powder, and a powder replenishing mechanism for transferring a necessary amount of powder calculated based on the analysis result of the Sn component in the plating solution from the hopper to the spray box. The plating apparatus according to claim 1 or 2 . A method of replenishing a Sn alloy component to the plating apparatus according to any one of claims 1 to 3 ,
An Sn component replenishing method for a plating apparatus, wherein the stannous oxide powder is sprayed on the plating solution in the tank while circulating the plating solution between the plating tank and the tank.

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