JP2001131797A - Semiconductor manufacturing method, and its device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semi conductor manufacturing method which can prevent adhesion of bubbles to a wafer surface to be treated and form a plating film uniform over the whole wafer surface to be treated, and its manufacturing device. SOLUTION: In the semi conductor manufacturing device in which the semi conductor wafer W is held by an upper part of a top-opened treatment tank 1 with its surface to be treated downside, current is allowed to flow between the semi conductor wafer and an anode 4 to implement the treatment including the plating and the chemical conversion to the semi conductor wafer W while jetting a treatment solution to the surface to be treated of the semi conductor wafer W forming a cathode, a sub flow path 1b which is branched from a main flow path 1a on the upstream side of the treatment solution flowing direction separately from the main flow path 1a to allow the treatment solution from the downstream to the upstream toward the semi conductor wafer W with its downstream end of the branched flow path opened in an external space with no semi conductor wafer present is provided, and the anode 4 is disposed within the sub flow path 1b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for manufacturing a semiconductor, and more particularly, to a jet-type plating method and a chemical conversion method used for forming bump electrodes and wiring on a semiconductor wafer and performing a chemical conversion treatment. In addition, the present invention relates to an apparatus used for them.

[0002]

2. Description of the Related Art When a semiconductor device is manufactured, a semiconductor wafer is sometimes subjected to plating or chemical conversion. For example, when manufacturing a DHD (Double Heatsink Diode) type diode, or TAB (Tape Automated B
When manufacturing a semiconductor device, a semiconductor wafer is made of 50 to 60 μm made of Ag, Au, Cu, solder or the like.
The bump electrodes of the order are formed. The wiring is formed of Au or another metal. When such bump electrodes and wirings are formed, a jet-type plating apparatus is generally used.

[0006] As shown in FIG. 6, this jet plating apparatus introduces a plating solution from the center of the bottom of the tank, and also has a jet-type plating tank 30 having an upper opening so that the plating solution overflows from the top of the tank. A mesh-like lower electrode 31 (anode) is provided near the bottom of the plating tank 30 to allow a plating solution to pass therethrough. On the other hand, the upper part of the plating tank 30 protrudes slightly from the upper end of the plating tank 30. A plurality of pin-shaped upper electrodes 32 (cathodes) are arranged at intervals, and a wafer W is placed on these upper electrodes 32 in a point contact state to form the wafer W as a substantial cathode. An electric current is caused to flow between the upper and lower electrodes while a plating solution is jetted on the lower surface of the wafer, thereby forming a plating film on the lower surface of the wafer.

[0004]

However, in this jet plating apparatus, a plating solution flows from a lower electrode (anode) arranged at the bottom of the processing tank to a wafer W arranged at the top of the processing tank. Therefore, bubbles generated from the anode surface reach the lower surface of the wafer W along the flow of the plating solution,
As a result, a phenomenon occurs in which plating does not adhere to the portion where air bubbles adhere. For example, in the case of copper plating, copper sulfate is used as a plating solution for copper plating, and platinum-plated titanium is used as a cathode. , Cu ²⁺ + 2e ⁻ → Cu chemical reaction occurs to form a plated film of copper, while 4OH ⁻
→ A reaction of 2H ₂ O + O ₂ + 4e ⁻ occurs to generate oxygen, which is released as bubbles into the plating solution. Since the specific gravity of the bubbles is lower than that of the plating solution and the flow of the solution is upward, the bubbles float in the plating solution and adhere to the lower surface of the wafer. If air bubbles adhere, a plating film is not formed on that portion, resulting in a defective product. Such a problem is not limited to the plating process, and is the same in other chemical conversion processes. The present invention is intended to solve such a problem, and it is an object of the present invention to provide a semiconductor manufacturing method and apparatus capable of preventing air bubbles from adhering to a wafer processing surface and forming a uniform plating film over the entire processing surface. Things.

[0005]

Means for Solving the Problems The present inventor has studied to solve such a problem, and if there is a method that does not allow bubbles to reach the wafer while flowing a plating solution from the bottom of the bath toward the top of the bath, the above problem will be solved. The present invention has been completed based on the idea that it can be solved.

The semiconductor manufacturing apparatus of the present invention completed on the basis of this idea holds a semiconductor wafer with its surface to be processed down on the upper portion of a processing tank having an open top, and receives the semiconductor wafer as a cathode. In a semiconductor manufacturing apparatus that performs a process such as plating and chemical conversion on a semiconductor wafer by flowing a current between the anode and a processing solution while jetting the processing solution on the processing surface, a main flow path that allows the processing solution to flow upward from the bottom toward the semiconductor wafer; Apart from that,
Dividing from the main flow path on the upstream side in the processing liquid flow direction,
It is characterized in that a sub-flow path is provided to an opening that opens to an external space through a flow path where no semiconductor wafer exists, and an anode is arranged in the sub-flow path.

In a semiconductor manufacturing apparatus having such a configuration,
The flow of the plating solution in the tank is divided into a main flow path in which a wafer is present on the upstream side of the flow path and a sub flow path in which no wafer is present and an anode is present. And is discharged from the downstream end of the sub flow path toward the external space. Note that the bubbles remain in the sub flow path,
Since a current flows through the liquid flow between the wafer serving as the cathode located in the main flow path and the anode located in the sub flow path, the formation of the plating film on the surface to be processed of the wafer is smoothly performed.

There are various possible ways of providing the sub-flow path and the anode. For example, the processing flow may be provided outside the main flow path from below to above the semiconductor flow toward the semiconductor wafer. A sub flow path, which is separated from the main flow path by a partition wall except for a distribution point at the bottom of the tank and has an opening at an upper portion that opens to an external space, is provided so as to surround the main flow path. It is a preferable example that a cylindrical electrode serving as an anode whose axial direction is substantially coincident with the vertical direction is provided therein. Further, a plurality of flat electrodes can be used instead of the cylindrical electrodes. In this case, it is preferable that these flat electrodes are arranged at intervals so as to surround the main flow path.

Although these inventions are for preventing air bubbles generated from the anode from adhering to the wafer, air bubbles may not be generated even in a jet plating apparatus. For example, the anode contains phosphorus-containing copper (phosphorus 0.2-0.3%
This is the case, for example, in the case of copper plating using (contained copper). In this case, at the cathode, a reaction of Cu ²⁺ + 2e ⁻ → Cu occurs to form a plated film of copper, while at the anode, Cu → Cu ²⁺ + 2e ⁻ copper dissolves in the liquid, but oxygen etc. Since no bubbles are generated, no bubbles are generated, and therefore, there is no problem of poor plating caused by adhesion of the bubbles.
However, dissolving the anode in the plating solution means that the impurities in the anode dissolve into the plating solution, and the anode becomes smaller and smaller. This means that maintenance is time consuming and workability is deteriorated. Needless to say, it is preferable that the plating apparatus has versatility capable of coping with such a case. In addition, both generation of bubbles and erosion of the anode may occur at the same time, and it is necessary to cope with such a case. To cope with such a case, it is preferable to use an anode material that is insoluble in a plating solution.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will now be described with reference to the illustrated embodiments. FIG. 1 is an explanatory diagram showing an outline of the first embodiment. The plating apparatus has a plating tank 1 provided with a main flow path 1a and a sub flow path 1b, a plating solution supply port 2 is provided at the bottom of the plating tank 1, and an anode is provided in the sub flow path 1b. On the other hand, a pin-shaped upper electrode 3 serving as a cathode is provided above the plating tank 1. In use, the semiconductor wafer W to be plated is placed on the upper electrode 3 with the surface to be treated facing down, the plating solution overflows from the upper opening of the plating tank 1, and the overflowing plating solution is subjected to the treatment. By immersing the surface, a plating film is formed on the surface to be processed.

The plating tank 1 is made of a synthetic resin having a corrosion resistance to a plating solution such as polypropylene, and has a shape with an open upper side. The plating tank 1 is supplied from a supply port 2 formed at the bottom of the tank. It has a dual structure in which a main flow path 1a for guiding liquid upward and a sub flow path 1b are provided outside the main flow path 1a so as to surround the main flow path 1a. The sub flow path 1b is diverted from the upstream side of the liquid flow flowing through the main flow path 1a, and the flow path 5 to the main flow path 1a on the upstream side is shielded from the main flow path 1a by a partition wall 6. In the sub flow path 1b shielded from the main flow path 1a, the main flow path 1
A cylindrical anode 4 is arranged in the vertical direction so that the axial direction of the anode 4 substantially coincides with the vertical direction so as to surround a. The anode 4 does not need to be reticulated because it does not need to pass a liquid flow as in the prior art. What is important here is that the bubbles generated from the anode 4 are prevented from wrapping around the main flow path 1a, and all the bubbles generated from the anode 4 float in the sub flow path 1b and flow through the sub flow path 1b. That is, the liquid is discharged to the external space from the opening 9 provided at the downstream end of the liquid flow. In order to realize this, in the present embodiment, the arrangement position of the anode 4 is set so that the most part in the height direction of the anode 4 is higher than the height position of the flow passage 5. In addition, since there is a liquid flow going downstream in the sub flow path 1b, the whole anode does not need to be arranged at a position higher than the flow path 5, and the lower end of the anode 4 is connected to the flow path as shown in the figure. 5 may be located on the side. If it is ensured that bubbles in the sub flow path 1b do not flow into the main flow path 1a, even if the whole anode is arranged at the same height position as the flow path 5, as in a third embodiment described later. Good. Here, a cylindrical electrode is used as the anode, but a non-cylindrical electrode may be used. For example, a plurality of flat electrodes may be arranged at intervals so as to surround the main flow path 1a.

The material of the anode 4a is insoluble in the plating solution to be used. For example, platinum titanium (titanium plated with platinum) or titanium iridium (titanium plated with iridium)
Are listed. When such an insoluble anode 4a is used,
This eliminates the need for anode replacement due to anode erosion and the problem of impurities being dissolved into the plating solution. On the other hand, the upper electrode 3 is a pin-shaped cathode electrode, and is provided at a plurality of positions above the plating tank 1 at intervals in the circumferential direction so as to protrude from the upper end of the plating tank 1 by about several mm. The wafer W is held on the pin-shaped upper electrode 3 in a point contact state with the surface to be processed facing down. In this apparatus having such a configuration, the plating solution jetted from below and impinging on the lower surface of the wafer overflows from the gap between the upper electrodes 3 to constantly supply a fresh plating solution to the lower surface of the wafer, whereby the wafer W It is used so that a plating film is formed on the substrate. Although not shown, the upper electrode may not be pin-shaped, but may be a U-shaped leaf spring having a certain height in plan view. In this case, the wafer W is supported in a line contact state by the U-shaped electrode. In these cases, the upper electrode is arranged on the lower surface of the wafer W. However, the upper electrode may be positioned on the back side of the wafer W, and the current may be supplied from the back surface of the wafer W.

A specific structure around the pin-shaped upper electrode includes, for example, the structure shown in FIG. In this arrangement, a surrounding member 7 made of ceramic is arranged around the pin-shaped upper electrode 3 with a gap 8 provided between the pin and the upper electrode 3, and an insulating fluid such as air flows through the gap 8. By preventing the plating solution from contacting the upper electrode 3, the upper electrode 3 is prevented from being corroded.

In the plating apparatus having such a structure, the liquid flow of the plating liquid ejected and supplied from the supply port 2 at the bottom of the tank is divided into a main flow path 1a and a sub flow path 1b toward the wafer on the upstream side of the liquid flow. The liquid flow rising through the main flow path 1a reaches the lower surface of the wafer W and passes through the flow path 5 to the anode 4 in the sub flow path 1b.
A plating film is formed on the lower surface of the wafer W by the electric current flowing between the two. On the other hand, air bubbles are generated from the anode 4 in the sub flow path 1b, but all of the air bubbles remain in the sub flow path 1b, float in the sub flow path 1b, and form a liquid flow in the sub flow path 1b. It is discharged to the external space from the opening 9 located at the downstream end. Therefore, bubbles do not adhere to the surface to be processed of the wafer W.

FIG. 3 shows a second embodiment.
In this embodiment, a plurality of supply ports 2a, 2a... Are provided at the bottom of the tank, and these are arranged in relation to the wafer W as shown in FIG. I have. Also, a recovery tank 10 for collecting the plating solution overflowing from the plating tank 1 is provided outside the plating tank 1,
A pump 11 and a filter 1
2. Supply ports 2a, 2 through flow control valves 13, 13, ...
a ... and the plating solution is refluxed.

Next, what is shown in FIG. 5 is not a cylindrical body with the anode standing upright as in the first and second embodiments, but an annular body flat in the horizontal direction. The annular anode 4a is arranged at the same height as the flow passage 5 with the main flow path 1a, and bubbles generated from the anode 4a by the liquid flow flowing outward in the sub flow path 1c in the main flow path 1c 1a.

Although each of the above-described embodiments has been described by taking plating as an example, the present invention is not limited to plating, for example,
It goes without saying that the present invention can be applied to a chemical conversion treatment such as anodic oxidation of aluminum.

[0018]

According to the present invention, a liquid flow flowing inside a processing tank such as a plating tank is divided at an upstream side thereof, so that a flow path in the tank is divided into a main flow path where a wafer is present and a wafer where a wafer is present. The sub-flow path, which has only the anode, is separated from the main flow path, in which the wafer is present, so that the air bubbles are prevented from adhering to the wafer. No defect such as occurrence of a portion where a plating film is not formed occurs.

Further, as set forth in claim 3, a sub-flow path which is separated from the main flow path and a partition wall except for a flow point at the bottom of the processing tank and has an opening to an external space at an upper portion outside the main flow path. Is provided so as to surround the main flow path, and in the sub-flow path, when a cylindrical electrode serving as an anode whose axial direction is substantially coincident with the vertical direction is provided, bubbles generated from the anode flow into the sub-flow path. It is possible to reliably discharge the air to the external space from the opening provided at the upper part of the road. In addition, since a cylindrical electrode whose axial direction is substantially coincident with the vertical direction is used as the anode, an increase in installation area due to the provision of the anode outside the main flow path can be minimized, and a compact device can be obtained. Can be provided.

As described in claim 4, when an anode which is insoluble in the plating solution is used as the anode disposed in the sub-flow path, the anode is not eluted into the plating solution. In addition to preventing impurities from being mixed, maintenance such as replacement of the anode is not required.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an outline of a first embodiment.

FIG. 2 is an explanatory view showing a specific example of a structure around a pin-shaped upper electrode.

FIG. 3 is an explanatory diagram showing an outline of a second embodiment.

FIG. 4 is an explanatory diagram showing an arrangement relationship of a supply port provided at a tank bottom with respect to a wafer.

FIG. 5 is an explanatory diagram showing an outline of a third embodiment.

FIG. 6 is an explanatory view showing an outline of a conventional plating tank.

FIG. 7 is an explanatory view showing a state in which bubbles float in a conventional plating tank.

[Explanation of symbols]

 W wafer 1 Plating tank 1a Main flow path 1b Sub flow path 1c Sub flow path 2a Supply port 4, 4a Anode 5 Flow path 6 Partition wall 7 Enclosure member 8 Void 9 Opening 10 Recovery tank 11 Pump 12 Filter 13 Flow control valve 30 Plating tank 31 Lower electrode 32 Upper electrode

Claims (4)

[Claims] 1. A semiconductor wafer is held with its surface to be processed down on an upper portion of a processing tank whose upper side is opened, and a processing solution is jetted onto the surface of the semiconductor wafer serving as a cathode and between the anode and an anode. In a semiconductor manufacturing method in which an electric current is applied to a semiconductor wafer to perform processing such as plating and chemical conversion, a processing liquid flows upward from a lower part toward a semiconductor wafer. A semiconductor manufacturing method in which an existing main flow path and a sub flow path in which an anode is present in the flow path are divided, and bubbles generated from the anode are discharged to the external space through the sub flow path without going around the main flow path. . 2. A semiconductor wafer is held with its surface to be processed down on an upper portion of a processing tank whose upper side is open, and a processing liquid is jetted onto the surface of the semiconductor wafer serving as a cathode between the anode and the anode. In a semiconductor manufacturing apparatus for applying a current to a semiconductor wafer to perform processing such as plating and chemical conversion, aside from a main flow path in which a processing liquid flows upward from below toward a semiconductor wafer, the main flow path is located upstream in a processing liquid flow direction. A semiconductor manufacturing apparatus comprising: a sub-flow path that branches to an opening that opens to an external space through a flow path in which a semiconductor wafer does not exist; and an anode is disposed in the sub-flow path. 3. A semiconductor wafer is held on the upper side of a processing tank having an open top with its surface to be processed facing down, and a processing liquid is jetted onto the surface of the semiconductor wafer serving as a cathode and between the anode and the anode. In a semiconductor manufacturing apparatus for applying a current to a semiconductor wafer to perform a process such as plating and chemical conversion, the semiconductor device includes a main flow path, except for a flow point at the bottom of a processing tank, outside a main flow path through which a processing solution flows upward from below toward a semiconductor wafer. A sub-flow path having an opening separated from the path by a partition and having an opening opening to an external space at an upper portion is provided so as to surround the main flow path, and an axial direction of the sub-flow path is set to a vertical direction in the sub-flow path. A semiconductor manufacturing apparatus provided with a cylindrical electrode serving as an anode substantially matched or a plurality of flat electrodes arranged at intervals so as to surround a main flow path. 4. The semiconductor manufacturing apparatus according to claim 2, wherein an insoluble anode is used as the anode disposed in the sub-flow path.