JP2006328470A - Electroplating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electroplating apparatus capable of completely discharging/draining a plating solution in a plating bath, effectively using the whole surface of a wafer and always supplying a fresh plating solution onto the surface of the wafer. <P>SOLUTION: The electroplating apparatus is provided with the plating bath 11 storing the plating solution M, an annular cathode auxiliary electrode holder 12 attached to a through hole of the bottom part 11b of the plating bath, a holder 13 for a material W to be plated which is detachably attached to the cathode auxiliary electrode holder and has a placing part 13c for the material to be plated on the upper surface, a cathode 15 provided on the upper side of the holder for the material to be plated and being in contact with the lower surface of the material to be plated on the placing part, positioning means 12d, 13d for the holder for the material to be plated, a paddle 23 moving back and forth on the wafer and an anode opposed to the cathode with a certain interval. The upper surface of the wafer and each surface of a cathode auxiliary electrode, the cathode auxiliary electrode holder and the bottom 17c, 12c, 11c are positioned on the same plane and then the plating solution is completely discharged and drained when the plating solution is discharged from the bottom of the plating bath after finishing of the plating. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electroplating apparatus for a substrate for electronic parts, a wafer for IC, a wafer for thin film magnetic head, and the like.

  Conventionally, an electroplating apparatus is used as an apparatus for forming a thin film on a wafer.

  In this electroplating apparatus, a conductive base film is provided in a portion where a plating film is to be formed, and the plating film is deposited on the base film by energizing the base film as a cathode in a plating solution.

The following are known as conventional electroplating apparatuses (for example, see Patent Document 1). That is,
As shown in FIG. 8, an annular cathode holder 2 mounted in a through hole in the bottom 1 b of the plating tank 1, a wafer holder 3 inserted into the cathode holder 2, and provided on the cathode holder 2, the wafer holder 3 An annular cathode (cathode) 5 in contact with the upper surface of the wafer W placed on the substrate, an annular cathode auxiliary electrode 7 provided on the cathode 5 via an insulator 6, An unillustrated anode (anode) provided facing the cathode 5 and a paddle 9 provided on the paddle sliding arm and sliding near the upper surface of the wafer W are provided.

  In FIG. 8, reference numeral 10a denotes an elevating cylinder for moving the wafer holder 3 up and down, 10b denotes a vacuum suction line, and 10c denotes a cathode power supply cord.

This electroplating apparatus is an apparatus for plating with the plating surface of the wafer W facing up, and plating is performed by contacting the outer periphery of the upper surface of the cathode (cathode) 5 and the wafer (substrate) W. In order to contact the both 5 and W, the disk-shaped wafer W is placed on the wafer holder 3 and pushed up by the elevating cylinder 10a to forcibly press the cathode 5 against the outer periphery of the upper surface of the wafer W.
JP-A-10-330987

  The conventional example has the following problems.

  (1) After the wafer processing, the automatic valve is opened and the plating solution in the plating tank 1 is discharged into the drain pipe, but there is a step D between the upper surface of the wafer W and the bottom 1b of the plating tank 1, for example, 4 Since a step of ˜5 mm is generated, the plating solution always remains at the bottom 1b of the plating tank. For example, when the wafer diameter is 150 mm, the amount of the residual plating solution is as large as 70 cc to 90 cc.

  Therefore, if the lifting cylinder 15a is lowered after draining, the residual liquid will be discharged to the outside as a spilled drain, so not only the loss of the plating solution but also the harmlessness must be discharged to the outside. Cost increases for maintenance.

  (2) Since the outer peripheral portion of the plating surface of the wafer W and the annular cathode 5 are in contact with each other, no film can be formed on the contacted portion. Therefore, the entire surface of the wafer W cannot be used effectively. Since the contact portion of the wafer W is, for example, about 4 mm, the effective area in the case of a wafer having a diameter of 150 mm is about 90%, and that in the case of a wafer having a diameter of 100 mm is 85%. Not good.

  (3) Since there is a liquid pool, the plating solution on the outer periphery of the wafer does not flow smoothly even if the paddle 9 is slid. Therefore, the film thickness cannot be uniformly formed.

  (4) Since a fresh plating solution is always supplied to the wafer surface, the paddle is desired to be as close to the wafer surface as possible, but cannot be within the step D. For example, the distance between the paddle 9 and the upper surface of the cathode auxiliary electrode 7 is about 1 mm, the step D is about 4 mm, and the distance between the wafer W and the paddle 9 is 5 mm, which cannot be made any closer. is there.

  In view of the above circumstances, an object of the present invention is to make it possible to completely drain the plating solution in the plating tank. Another object is to effectively use the entire surface of the wafer and to obtain a uniform film thickness. Yet another object is to always be able to supply fresh plating solution to the wafer surface.

  The present invention includes a plating tank for storing a plating solution, an annular cathode auxiliary electrode holder mounted in a through-hole at the bottom of the plating tank, and a cathode auxiliary electrode holder that is detachably attached to the upper surface of the cathode auxiliary electrode holder. A plated object holder having a placement part for the plated object, a cathode provided on the upper surface side of the plated object holder and contacting the lower surface of the plated object on the placing part, and the plated object holder It is characterized by comprising positioning means for restricting the fixed position, and an anode provided in the plating tank and facing the cathode at a distance.

  The present invention includes a plating tank for storing a plating solution, an annular cathode auxiliary electrode holder mounted in a through hole at the bottom of the plating tank, and an annular cathode auxiliary electrode provided on the upper surface of the cathode auxiliary electrode holder. A plating object holder that is detachably inserted into the cathode auxiliary electrode holder and has a placement part for the object to be plated on the upper surface thereof, and is provided on the upper surface side of the plating object holder. A cathode in contact with the lower surface of the plated object; a vacuum suction means provided on the object holder; a positioning means for regulating a fixing position of the object holder; and a space provided between the cathode and the cathode. And a paddle slidably provided on the bottom side of the plating tank.

  The present invention is characterized in that the cathode contacts the lower surface of the object to be plated through the contact ring. A wafer is placed on the placing portion of the object holder of the present invention, and the plating surface of the wafer and the upper surface of the cathode auxiliary electrode holder are located on the same plane. The positioning means of the present invention comprises an engaging portion provided on the inner peripheral surface of the cathode holder, and an engaging portion provided on the outer peripheral surface of the workpiece holder and engaged with the engaging portion. Features. The present invention is characterized in that the cathode auxiliary electrode holder includes a presser claw for pressing the plating surface of the object to be plated.

  Since this invention is provided with the positioning means which regulates the fixing position of the holder of a to-be-plated object, the plating surface of a to-be-plated object and the bottom face of a plating tank can be located on the same plane. For this reason, a step difference as in the conventional example does not occur at the bottom of the plating tank, and so-called liquid pool does not occur. Therefore, when drain draining is performed every time plating is completed, the entire plating solution in the plating tank can be collected in the circulation tank.

  Since the cathode is provided on the lower surface side of the object to be plated, there is no obstacle on the plating surface. Therefore, when plating an object to be plated, for example, a wafer, the entire surface of the wafer can be used effectively. Further, since the paddle can be brought as close to the plating surface as possible, a fresh plating solution can always be supplied.

  Since the presser claw is provided, for example, even if the vacuum pump of the vacuum suction line fails and a vacuum break occurs, the object to be plated can be securely fixed. In addition, since this nail | claw is provided with two or more intervals in the circumferential direction, the contact area of a plating surface and a press nail | claw is also very small. Therefore, it hardly affects the yield.

  A first embodiment of the present invention will be described with reference to FIGS.

  The electroplating apparatus includes a box-shaped plating tank 11. A through hole is provided at the center of the bottom 11 b of the plating tank 11, and a cylindrical cathode auxiliary electrode holder 12 is inserted into the through hole. It is worn.

  An electrode housing recess is provided on the upper surface 12c of the cathode auxiliary electrode holder 12, and an annular cathode auxiliary electrode 17 is fitted in the recess. The cathode auxiliary electrode 17 prevents concentration of current on the outer peripheral portion h of the wafer W, and the electrode 17 can prevent unevenness of the film thickness.

  More specifically, since the anode 19 and the cathode 15 are opposed to each other with a predetermined distance, the current density is different between the center and the end of the cathode 15 and the current density distribution on the surface of the cathode 15 becomes non-uniform. . However, when the auxiliary cathode electrode 17 is provided so as to surround the cathode 15, the current density distribution on the cathode 15 becomes uniform, and the film thickness can be made uniform.

  The electrode 17 is connected to a cathode auxiliary electrode power source via a cord 17a. The upper surface 17c of the electrode 17, the upper surface 11c of the bottom 11b, and the upper surface 12c of the holder 12 are located on the same plane. A step portion 12 d serving as a locking means is formed on the upper portion of the inner peripheral surface of the holder 12.

  A workpiece holder 13 is inserted into the holder 12. The upper surface 13c of the holder 13 forms a flat mounting portion, and a step portion 13d serving as an engaging means is formed on the upper portion of the outer peripheral surface. The step portion 13d is engaged with the step portion 12d.

The upper surface 13c is formed with an electrode housing recess 16, a plurality of seal grooves 13e, and a suction hole 13f. The cathode housing recess 16 includes an inner groove 16a and an outer notch 16b, and the outer notch 16b is formed on the outer peripheral side. The inner groove 16 a is fitted to the cathode 15, and the top of the cathode 15 is located below the upper surface 13. The cathode 15 is connected to a cathode power source via a cord 15a.
N
A horizontal fixing portion 36a of a contact ring 36 is fixed to the cathode 15 by a holding bolt 37. The head of the bolt 37 is located below the upper surface 13c. The horizontal fixing portion 36a of the contact ring 36 is connected to the horizontal abutting portion 36c through an inclined connecting portion 36B.

  An elastic member, for example, rubber 38 is fitted into the outer notch 16b. The rubber 38 is formed in a rectangular shape in cross section, and the contact portion 36c of the contact ring 36 is pressed against the upper surface 38a. The contact portion 36c is pressed by the lower surface of the outer peripheral portion of the wafer W.

  A sealing material such as a rubber O-ring 40 is fitted in the sealing groove 13e. The suction hole 13 f is continuous with the vacuum suction line 32. The holder 13 is fixed to the elevating cylinder 25.

  A paddle 23 is slidably provided in the plating tank 11. The paddle 23 is provided on the paddle sliding arm 21. The paddle 23 is reciprocated as close to the wafer W as possible in order to always flow a fresh plating solution.

  In FIG. 4, 27 is a drain pipe for returning the plating solution M in the plating tank 11 to a circulation tank (not shown), 28 is an automatic valve provided in the drain pipe 27, 29 is overflowed, and the plating solution is circulated. The overflow part 30 which returns to a tank and 30 respectively show the plating solution circulation supply part to which a plating solution is supplied from the said circulation tank.

  Next, the operation of the present embodiment will be described.

  When an object to be plated, for example, a wafer W, is placed on the placement portion 13c, the contact portion 36c of the contact ring 36 is brought into contact with the outer peripheral portion of the lower surface of the wafer W, and then the vacuum suction line 32 is driven. The wafer W is attracted and fixed to the mounting portion 13c. At this time, the upper surface of the contact portion 36c and the upper surface 13c of the holder 13 are positioned on the same plane, and the wafer W is in a horizontal state.

  When the elevating cylinder 25 is driven and the workpiece holder 13 is inserted into the cathode auxiliary electrode holder 12, the step 13d of the holder 13 engages with the step 12d of the holder 12 and cannot slide any further. At this time, the upper surface of the wafer W and the upper surfaces 17c, 12c, and 11c of the auxiliary cathode electrode 17, the auxiliary cathode electrode holder 12, and the bottom portion 11b are located on the same plane.

  In this state, the plating solution M is supplied to the plating solution tank 11, and the cathode 15, the anode 19, and the cathode auxiliary electrode 17 are supplied with power, and the paddle 23 is slid to remove the fresh plating solution M from the plating surface of the wafer W. And plating. At this time, since there are no obstacles on the upper surface of the wafer W, the paddle 23 slides in the vicinity of the upper surface of the wafer W, for example, at a position about 1 mm or more upward from the wafer W, so that the plating is always fresh. The liquid can be supplied to the plating surface of the wafer W.

  In addition, since the contact ring 36 is located on the outer peripheral side of the wafer W, the electrical conductivity to the plated surface of the wafer surface is good. Further, since the rubber 37 is provided, even if the contact portion 36c of the contact ring 36 is slightly higher than the upper surface 13c, the height can be adjusted by elastic deformation.

  After the wafer plating is completed, the automatic valve 28 is opened, and the plating solution M in the plating tank 11 is poured into a circulation tank (not shown) through the drain pipe 27. At this time, the upper surfaces 12c, 13c and 11c of the holders 13 and 12 and the bottom portion 11b are located on the same plane, so that the plating solution M in the plating tank 11 is completely drained and discharged to the circulation tank. Collected.

  Therefore, even if the elevating cylinder 25 is operated and the object holder 13 is lowered, there is no liquid pool in the bottom 11b of the plating tank 11, so that the plating solution M is discharged to the outside. Absent. Further, unlike the conventional example, the plated surface of the wafer is not pressed by the cathode or the like, so that the entire surface can be used effectively.

  A second embodiment of the present invention will be described with reference to FIG. 5. The same reference numerals as those in FIGS. 1 to 4 have the same names and functions.

  The difference between this embodiment and the previous embodiment is that the contact ring is omitted and the cathode 15 and the wafer W are brought into direct contact with each other.

  A third embodiment of the present invention will be described with reference to FIGS. 6 and 7. The same reference numerals as those in FIGS. 1 to 4 have the same names and functions.

  The difference between this embodiment and the above-described embodiment is that the cathode auxiliary electrode holder 12 is provided with a presser claw 35 for pressing the plating surface (upper surface) of the wafer. As shown in FIG. 7, four presser claws 35 are provided at equal intervals in the circumferential direction and are in contact with the vicinity of the outer peripheral edge of the wafer W. The number, size, arrangement, and the like of the presser claws 35 can be appropriately selected as necessary.

  Since the number of the press claws 35 is small and the contact area with the wafer is also small, the yield is hardly affected. By providing this presser claw 35, even if the vacuum suction line 32 breaks down, the wafer can be securely fixed.

FIG. 3 is a cross-sectional view showing the first embodiment of the present invention, and is an enlarged cross-sectional view of a main part taken along line II of FIG. It is a top view of an electroplating apparatus. It is a principal part expanded sectional view of FIG. It is the front view which made the cross section part of the electroplating apparatus. It is a principal part expanded sectional view which shows 2nd Embodiment of this invention. It is a longitudinal cross-sectional view which shows 3rd Embodiment of this invention, and is a figure corresponding to FIG. It is a top view of an electroplating apparatus. It is an expanded sectional view which shows a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Plating tank 11b Bottom part 11c Upper surface 12 Cathode auxiliary electrode holder 12c Upper surface 12d Step part 13 To-be-plated object holder 13c Upper surface 13d Step part 15 Cathode 17 Cathode auxiliary electrode 19 Anode 23 Paddle 35 Pressing nail

Claims (6)

A plating tank for storing a plating solution;
An annular cathode auxiliary electrode holder fitted in the through hole at the bottom of the plating tank;
To-be-plated object holder slidably inserted in the cathode auxiliary electrode holder and having a placement part for the object to be plated on the upper surface thereof;
A cathode which is provided on the upper surface side of the object holder and contacts the lower surface of the object to be plated on the mounting portion;
Positioning means for regulating a fixed position of the workpiece holder;
An anode provided in the plating tank and facing the cathode at an interval;
An electroplating apparatus. A plating tank for storing a plating solution;
An annular cathode auxiliary electrode holder fitted in the through hole at the bottom of the plating tank;
An annular cathode auxiliary electrode provided on the upper surface of the cathode auxiliary electrode holder;
A to-be-plated object holder that is detachably attached to the cathode auxiliary electrode holder and has a placement part for the to-be-plated object on the upper surface thereof;
A cathode which is provided on the upper surface side of the object holder and contacts the lower surface of the object to be plated on the mounting portion;
Vacuum suction means provided on the workpiece holder;
Positioning means for regulating a fixed position of the workpiece holder;
An anode provided in the plating tank and facing the cathode at an interval;
A paddle slidably provided on the bottom side of the plating tank;
An electroplating apparatus.   The electroplating apparatus according to claim 1, wherein the cathode contacts the lower surface of the object to be plated through a contact ring.   The wafer is mounted on the mounting portion of the object holder, and the plating surface of the wafer and the upper surface of the cathode auxiliary electrode holder are located on the same plane, or 3. The electroplating apparatus according to 3.   The positioning means includes an engaging portion provided on the inner peripheral surface of the cathode holder, and an engaging portion provided on the outer peripheral surface of the workpiece holder and engaged with the engaging portion. The electroplating apparatus according to claim 1, 2, 3, or 4.   6. The electroplating apparatus according to claim 1, wherein the cathode auxiliary electrode holder includes a pressing claw for pressing a plating surface of an object to be plated.

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