JPH0568559B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a technique that is effective when applied to a plating apparatus, particularly a plating apparatus used for forming protruding electrodes provided on a pellet of a semiconductor device.

[Background Art] In the manufacturing process of semiconductor devices provided in a tape carrier state, a plating process is performed to form bump electrodes made of gold (Au) on pads of wafers on which predetermined circuits are formed. In this plating process, a photoresist layer with only the plating area exposed to the outside is first formed on a wafer as a processing object, and a plating solution is applied with the wafer facing the anode plate, with the wafer as the cathode side. Place in a filled electrolytic cell. In this state, by applying a current of a predetermined value between the cathode and the anode, the photoresist layer serves as a mask and a metal layer is deposited by electrodeposition on the exposed plating area of the wafer on the cathode side. After the metal layer has been formed to a predetermined thickness, the wafer is taken out of the electrolytic bath, and the photoresist layer is dissolved and removed to form bump electrodes.

By the way, in the plating apparatus using the above technology, the gold in the plating solution causes a chemical reaction on the surface of the anode plate and becomes a colloid, which is transferred to the plating area of the wafer on the cathode side by the flow of the plating solution. There is a possibility of adhesion.

When this colloid adheres to the plating area, the bump electrode that is formed becomes an abnormal protrusion, and when thermocompression bonding the lead onto the bump electrode, there is a real possibility that the pressing force will be concentrated in this area and cause the electrode to break. Revealed by the inventor.

In addition, in the plating apparatus using the above technology, since the anode is formed over almost the entire surface of the anode plate, the wafer surface facing the anode is exposed to the wafer surface as it moves toward the periphery of the wafer. Current density increases. Therefore, only the bump electrodes located in the circumferential direction of the wafer are formed thickly, and the size of the bump electrodes formed at different parts of the wafer becomes non-uniform. It was revealed that

A detailed example of the technology for tape carrier type semiconductor devices in which bump electrodes are formed is "IC Mounting Technology" published by Kogyo Kenkyukai Co., Ltd., January 15, 1980 (edited by the Japan Microelectronics Association). ), there are P143-P144.

[Object of the Invention] An object of the present invention is to provide a technique that can form a metal layer with a uniform thickness over the entire area of a workpiece.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Summary of the Invention] A brief overview of typical inventions disclosed in this application is as follows.

In other words, the plating apparatus has an electrolytic cell in which an object to be treated as a cathode and an anode plate are positioned facing each other, and a means for generating a flow of plating liquid from the object to be treated toward the anode plate. Since the colloid formed on the anode part is flowed in the opposite direction of the object to be treated by the liquid flow, it is possible to prevent the colloid from adhering to the plating area of the object to be treated, and to prevent abnormal protrusions. It is possible to prevent the metal layer from forming and form a metal layer with a uniform thickness over the entire area of the object.

[Example] FIG. 1 is a schematic diagram showing a plating apparatus that is an example of the present invention.

The plating apparatus 1 of this embodiment is for forming bump electrodes made of gold on pellets of semiconductor devices provided in the form of tape carriers.
Since the bump electrodes are formed on the wafer before it is divided into pellets, the objects to be processed in this embodiment are the wafers 4a and 4b.

The plating apparatus 1 has an electrolytic tank 3 filled with a plating solution 2, which is an electrolytic solution, and a jig plate 5 with wafers 4a and 4b attached to both sides stands approximately in the center of the electrolytic tank 3. It is located in the set condition. Here, both wafers 4a and 4b are fixed to a jig plate 5 by stoppers 6a and 6b made of a conductive material, and pads (not shown) on the surfaces of the wafers 4a and 4b are electrically connected to the outside via the stoppers 6a and 6b. The wafer 4a,
The structure is such that a direct current is applied such that 4b forms a cathode. Here, a predetermined circuit (not shown) is formed on the surfaces of the wafers 4a and 4b, and a photoresist layer is further formed on top of the predetermined circuit. This photoresist layer is formed over almost the entire surface of the wafers 4a and 4b, excluding only the surface of the pad made of aluminum and plating base metal, which is the plating area.

In the electrolytic bath 3, anode plates 7a and 7 are disposed on the jig plate 5 at opposing positions with a predetermined distance from both wafer surfaces.
b are each erected.

These anode plates 7a, 7b have a mesh-like anode portion 8a,
8b, and these anode portions 8a, 8b are located opposite to the wafers 4a, 4b.
It is formed in a circular shape almost the same as b. Further, filters 9a and 9b shown by two-dot chain lines may be attached to the anode parts 8a and 8b.

The anode plates 7a and 7b have a cylindrical shielding tube 1 extending vertically from the periphery of the anode parts 8a and 8b toward the jig plate 5.
0a and 10b are extended, and this shielding tube 1
The inner diameters of 0a and 10b are also approximately the same as the diameters of wafers 4a and 4b. Note that the shielding tube 10
A gap is formed between the tip portions of wafers 4a and 10b and wafers 4a and 4b, through which plating liquid 2 can flow. In this way, the anode parts 7a and 7b are connected to the wafer 4a,
By forming shielding cylinders 10a, 10b around the anode portions 8a, 8b in the same shape as the wafers 4a, 4b at opposite positions of the anode portions 8a, 8b, the current from the anode portions 8a, 8b is transferred to the anode plates 7a, 7b. The current is applied to the cathode side wafers 4a and 4b while maintaining a uniform current density in a direction substantially perpendicular to the cathode side. Therefore, it is possible to form uniform bump electrodes over the entire surface of the wafers 4a, 4b.

Inflow ports 11a and 11b are opened toward the inside of the electrolytic cell 3 at a portion partitioned by the jig plate 5 and the anode plates 7a and 7b, while the anode plates 7a and 7b and the tank walls 12a and 12b are connected to each other. Outflow ports 13a and 13b are opened in the partitioned portion. The inflow ports 11a, 11b and the outflow ports 13a, 13b are communicated through flow pipes 14a, 14b, and a pump 15 is interposed in the middle of the flow pipe 14. Although not shown, in addition to the pump 15, a filter, a flow meter, or the like may be interposed in the flow pipe 14.

The operation of this embodiment will be explained below.

The wafers 4a and 4b are fixed to the jig plate 5.
is placed in the liquid, a predetermined amount of current is applied to the anode portions 8a, 8b and the wafers 4a, 4b, which serve as cathodes, and due to electrolytic action, the metal layer in the plating area on the wafer is gradually deposited and plated. Processing begins. At the same time, the pump 15 is started to flow the plating liquid 2 from the outlet ports 13a and 13b through the flow pipes 14a and 14b into the electrolytic cell 3 from the inlet port 11a. The tamping liquid 2 that flows into the electrolytic cell 3 from the inlet 11a passes through the section partitioned by the anode plates 7a, 7b and the jig plate 5, and then passes through the shield tubes 10a, 10.
It passes through the gap between the tip of wafer b and wafers 4a and 4b and flows into the interior of shielding cylinders 10a and 10b. Further, the plating liquid 2 flows from the inside of the shielding cylinders 10a, 10b to the anode parts 7a, 7b, but since the anode parts 8a, 8b are formed in a mesh shape through which the liquid flow can pass, the plating The liquid 2 passes through the anode portions 8a and 8b, and reaches the anode plates 7a and 7b and the tank walls 12a and 12b.
flows into the area surrounded by. Then, the plating liquid 2 is sent to the pump 15 again through the outlets 13a and 13b.

As described above, inside the shielding cylinders 10a, 10b, the liquid flow flows from the wafers 4a, 4b to the anode parts 8a, 8.
Since the liquid advances in the direction b, the colloid generated in the anode portions 8a and 8b flows in the opposite direction to the wafers 4a and 4b, adheres to the filters 9a and 9b, and is removed from the liquid flow. Therefore, the colloid does not adhere to the plating areas of the wafers 4a and 4b, and the formation of abnormal protrusions on the bump electrodes can be prevented.

[Effects] (1) A plating device having an electrolytic cell in which an object to be treated as a cathode and an anode plate are positioned facing each other, and a means for generating a flow of plating liquid from the object to be treated toward the anode plate. By using this device, the colloid formed on the anode part is flowed by the liquid flow in the opposite direction to the object to be treated, so that it is possible to prevent the colloid from adhering to the plating area of the object to be treated. , it is possible to prevent the formation of abnormal protrusions and form a metal layer with a uniform thickness over the entire area of the object to be processed.

(2) By providing a shielding tube with an inner diameter that is approximately the same as the object to be processed from the anode section of the anode plate toward the object to be processed, the current from the anode section can be uniformly distributed in the direction approximately perpendicular to the anode plate. Since the current is applied to the object on the cathode side while maintaining the current density, a uniform metal layer can be formed regardless of the position on the object.

(3) According to (1) and (2) above, highly reliable plating processing can be performed.

Although the invention made by the present inventor has been specifically explained based on Examples above, the present invention is not limited to the Examples described above, and it is understood that various changes can be made without departing from the gist of the invention. Needless to say.

For example, in the embodiment, a case has been described in which wafers are mounted on both sides of the jig plate, but wafers may be mounted only on one side.

[Field of Application] In the above description, the invention made by the present inventor was mainly applied to a plating apparatus for forming bump electrodes on pellets of a tape carrier type semiconductor device, which is the field of application of the invention. The present invention is not limited to this, but it is also an effective technique when applied to a plating apparatus for forming bump electrodes made of pellet solder or the like for so-called surface mounting, or for forming other metal layers.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a plating apparatus that is an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Plating device, 2...Plating liquid, 3...Electrolyte layer, 4a, 4b...Wafer, 5...Jig plate, 6
a, 6b... stopper, 7a, 7b... anode plate,
8a, 8b... Anode part, 9a, 9b... Filter, 10a, 10b... Shielding tube, 11a, 11
b... Inlet, 12a, 12b... Tank wall, 13
a, 13b... Outlet, 14a, 14b... Distribution pipe, 15... Pump.

Claims (1)

[Claims] 1. Having a plating liquid inlet located at the center of the bottom,
An electrolytic cell having a plating liquid outlet located near the bottom corner thereof, and an internal tank portion within the electrolytic cell that stores the plating liquid that flows in from the plating liquid inlet, and the plating liquid. A pair of anode plates are provided at a distance from each other to partition the outer tank part that stores the plating solution to flow out to the outlet, and each of the pair of anode plates is provided with a pair of anode plates facing each other in the inner tank part. A treatment for the workpiece is provided between the opposing shielding cylinders so that the surface of the workpiece serving as a cathode to be plated is directed toward the shielding cylinder. A plating device configured such that a plating plate is positioned thereon, and each of the pair of anode plates is provided with a mesh portion that allows plating to pass from the inside of the shielding cylinder to the external tank portion. . 2. The plating apparatus according to claim 1, wherein a filter is provided in the mesh-like portion of the anode plate through which the plating solution passes.