JPH0441699A - Method and equipment for plating wafer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a wafer plating method for forming a bonding ink connection portion (hump) to a printed circuit board on a wafer on which an IC (integrated circuit) is formed. and regarding its equipment.

[Prior Art] In the manufacturing process of integrated circuits, an integrated circuit formed on the surface of a wafer is
A bump forming process for forming a bonding hang is included in the C-glue portion.

For this hang forming process, a method using vapor deposition and a method using plating are mainly used, and the present invention is directed to the latter method.

The outline of the hump forming process using the conventional plating method is shown in Figure 3 (a).
) ~ (C) To explain, first, the intermediate metal that also serves as a common electrode for plating! ! j (for example, ^1 / Cr
/Cu) is deposited on the entire surface of the wafer, a resist (solder adhesion prevention) 101 is formed on the front and back surfaces of the wafer W, and each IC glue portion 102 is exposed to light to remove the resist 101 only in that portion ( Figure (a)).

Next, a plating process to be described later is performed to form a Cu plating top 103 on the leat portion 102 of each IC, and further.

Layer solder plating 1'1J104 on top of Cu plating layer (
Figure (b)). Thereafter, the resist 101 and the unnecessary common electrode layer were removed, and the solder layer plating 104 was reflowed to form a hump V (FIG. 3(C)).

In the plating process, as shown in FIG. 4(a), wafers W are arranged side by side in plating #allO filled with plating solution, each wafer W is used as a negative electrode, and a positive electrode is placed opposite to the wafer W. This was done using a configuration in which an electrode 111 was provided.

[Problem to be Solved by the Invention] Incidentally, since the IC bonding work is automatically performed, it is preferable that the plating layer of each integrated circuit has a uniform thickness.

However, the conventional plating method described above is
), the plating layer had a drawback that the plating layer was thicker at the edge of the wafer W than at the center. The theoretical cause of this is that the electric lines of force E are concentrated at the edge of the wafer due to bending, and the ions generated on the electrostatic electrode 111 move along the lines of electric force. Furthermore, it is conceivable that the ions generated at the positive electrode Ill are likely to be dissipated around the opposing wafer W, and may be incident on the edge of an adjacent sea urchin.

Therefore, a metal ring is provided around the wafer W, and the positive electrode 111
A method of dispersing the ions from outside the edge of the opposing wafer has also been adopted, or even such methods have not sufficiently solved the above-mentioned drawbacks.

Further, as shown in FIG. 5, a cylindrical plating injection nozzle 11
2, a wafer W is placed near the opening at one end of the nozzle 112, and this wafer W is used as a negative electrode,
A positive electrode 113 is provided in the hollow part of the nozzle 112, and the plating liquid 114 is applied from the other end of the nozzle 112 to the surface of the wafer W.
A method of plating by spraying was also used. This method has a structure in which the wafers W are mounted and plated one by one, so it has the disadvantage that the workability is poor for processing a large number of wafers, and the equipment cost is extremely high. In addition, it is difficult to equalize the jet pressure and jet velocity at the center and edge of the wafer W, making it difficult to obtain a uniform plating thickness.Furthermore, when the plating thickness of each IC on the wafer is measured, - The thickness of the plating inside the hump was uneven, and the plating 114 was formed to protrude laterally due to the injection pressure of the plating solution, resulting in an irregular shape as shown in FIG. 5(b).

The present invention has been made to solve these drawbacks, and provides a wafer plating method that can form a plating layer with a uniform thickness, and a wafer plating apparatus that can carry out the same method with a simple configuration. The purpose is to provide.

[Means for Solving the Problems] In order to achieve the above object, the wafer plating method of the present invention prepares a cylindrical body having an opening surface at one end that substantially matches the front shape of the wafer, and There is a method in which the wafer placed at one end is used as a negative electrode, and the other end of the cylindrical body is used as a positive electrode, and the wafer is left in a plating solution for a predetermined period of time. A plating liquid jet may be formed in the peripheral area.

The wafer plating apparatus of the present invention includes a cylindrical body having an opening at one end that substantially matches the front shape of the wafer, a wafer fixing means provided at one end of the cylindrical body, and a wafer fixed to the wafer fixing means. The configuration includes means for using the wafer as a negative electrode, and a positive electrode provided on the other end side of the cylindrical body, and in a preferred embodiment, the surface of the wafer fixed to the wafer fixing means or its surroundings. A structure may be provided in which a means for spouting a plating solution is provided.

[Function] Since the wafer plating method and its apparatus of the present invention have the above-described configurations, the lines of electric force are confined and linearly extended by the cylindrical body having an opening at one end that substantially matches the surface shape of the wafer. As a result, the ions generated at the positive electrode can be guided to the front of the wafer, greatly reducing the possibility of them being dispersed around the wafer or concentrating on the edge of the wafer, resulting in a plating layer with an almost uniform thickness over the entire front surface of the wafer. or formed.

Furthermore, by forming a jet of plating liquid almost parallel to the surface of the sea urchin, the difference in the supply speed of plating ions caused by the arrangement of the bumps 104 in the IC chip can be eliminated, and each The plating layer inside the IC is also formed to have a uniform thickness and a desired shape.

[Example] An example of the present invention will be described below with reference to the drawings.

FIG. 1 is a partially cutaway perspective view showing the overall configuration of an embodiment of the wafer plating apparatus of the present invention, FIG. 2(a) is a sectional front view of the same apparatus, and FIG. be.

In FIG. 1, reference numeral 1 denotes a unit of a wafer plating apparatus (hereinafter referred to as a plating unit) according to the present embodiment, and a large number of units are installed in a plating tank 2 at different intervals. Each plating unit 1 is shown in FIG. 2(a).

As shown in (b), the wafer is housed in a housing 3, and the wafer is attached to a cylindrical body 4 and a plate (
The wafer mounting is provided with means) 5. A notch 3a for the plating solution to flow in is provided at the upper edge of the housing 3.

The cylindrical body 4 is made of an insulating material such as plastic, and the opening surface 4a at one end is formed in a shape that almost matches the front shape of the wafer W. By the way, in wafer W,
Since an orientation flat for positioning is formed, the accurate front shape is not circular, or even if the opening surface shape of the cylindrical body 4 is circular, this degree is within an allowable range. Furthermore, as will be described later, in order to generate a jet onto the wafer W, a gap d is required between the wafer W and the opening surface 4b, so that the lines of electric force flow outward. Therefore, it is preferable that the diameter of the opening of the cylindrical body be slightly smaller than the diameter of the wafer, or a certain degree of size may be allowed. As a result of the experiment, the shape of the opening of the cylindrical body 4 was circular, the diameter of the opening was 9.0C11 to 12.5cm for a 5-inch wafer W, and the diameter of the opening for a 4-inch wafer W was 9.0cm to 12.5cm. Diameter 7.0C11%10.0C
Within the range (2), the effects of the present invention can be sufficiently obtained. Can the shape of the hollow part of the cylindrical body 4 other than the opening surface be arbitrary?
Preferably, the length of the cylindrical body 4 is the same as the shape of the opening from one end to the other end, and the length of the cylindrical body 4 may be arbitrary, preferably 5 to 15 cm for a 5 inch wafer W.
It is set to about 5 to 15 centimeters even for a 4-inch wafer W.

A plate-shaped positive electrode 6 is provided at the other end of the cylindrical body 4 and is connected to a power source 7. The positive electrode 6 is provided with a through hole 8 for forming a flow of the plating solution within the hollow portion 4b.

The output of the power source 7 may be appropriately adjusted with reference to known wafer plating technology.

The wafer mounting plate 5 is a member that tightly fixes the wafer W on the side surface and arranges the wafer W near the opening surface 4a of the cylindrical body 4. Here, it is most preferable to have no gap between the wafer W and the opening surface 4a.As will be described later, it is necessary to spray the plating solution onto the peripheral part of the surface of the wafer W, so the required gap d is determined.
must be ensured. As a result of the experiment, 4 inches, 5
It has been found that the effects of the present invention can be obtained as long as the gap is within d or 20 inches with respect to the wafer W in both cases.

Further, the wafer W fixed to the plate 5 is attached to the negative electrode 9.

In FIGS. 1, 2(a) and 2(b), reference numeral 10 denotes a plating spouting pipe serving as a means for spouting plating solution onto the interstices of the surface of the wafer W, and is installed below the gap d. .

The plating jet pipe 10 is provided with a large number of nozzles loa, and these nozzles loa are directed toward the surface of the wafer W. As shown in FIG. 1, this plating jet pipe IO is connected to a flow meter 12 or a circulation pump 13 via a pipe 11. The circulation pump 13 sucks the plating solution in the plating tank 2 through the suction pipe 14 and supplies the plating solution to the pipe 11.
It is supplied into the plating jetting vibe 10 of each plating unit l through the plating unit L.

Next, an embodiment of the wafer plating method of the present invention using the above-described embodiment apparatus will be described.

The plating solution in the plating tank 2 is slowly circulated between a temperature control tank and a filter tank (not shown). The plating solution flows into the casing 3 of the plating unit 1 through the notch 3a.

A wafer mounting plate 5 for fixing the wafer W is installed in advance near the opening surface 4a of the cylindrical body 4, and
is connected to the negative electrode 9. Then, a current is passed from the positive electrode 6 provided at the other end of the cylindrical body 4 toward the negative electrode 9 at a constant current density for a predetermined period of time. Here, the cumulative amount of current (=current amount x time (amP-H)) to be passed through the positive electrode 6 is experimentally set to the best value depending on the specific device.

In the above-mentioned state, ions are generated in the positive electrode 6, migrate to the wafer W through the hollow part 4a of the cylindrical body 4, and perform plating on the surface of the wafer W. Here, the cylindrical body 4 has an opening surface that almost matches the front shape of the wafer W, and since the wafer W is fixed near the opening surface 4a, the ions do not dissipate and the wafer W Proceeds to the surface and forms a plating layer of uniform thickness.

In addition, during the plating process, the plating liquid is ejected from the plating ejection vibrator 10, and the gap d between the wafer W and the opening surface 4a of the cylindrical body 4 is
A jet of plating solution is formed around the surface of the wafer W through the plating solution. Here, the jet state refers to a state in which the plating solution in contact with the surface of the wafer W is constantly flowing.As a result of forming such a jet state, plating ions due to the arrangement of the humps 104 in the IC chip Since the difference in the supply speed of the plating is eliminated, the plating layer in each integrated circuit on the W is formed with a uniform thickness, and the plating layer is formed in the desired shape without adhesion or protrusion of excess plating. be done.

Note that the present invention is not limited to the above-described embodiment.

For example, the wafer plating apparatus of the present invention may be installed directly in a plating tank without being made into a unit.1 In addition, it is possible to eliminate the difference in thickness between the edge and center of the plating layer for the entire wafer. In the case where the thickness accuracy of each individual plating layer of each IC is not considered for the purpose of the present invention, it is not necessary to form a plating liquid jet state around the periphery of the wafer surface. In this case, the sea urchin A can be fitted into the opening of the cylindrical body to eliminate the gap d.

[Effects of the Invention] As explained above, according to the wafer plating method of the present invention, it is possible to form a plating layer with a uniform thickness over the entire wafer, and furthermore, it is possible to form a plating layer with a uniform thickness over the entire wafer. If a jet state is formed, the plating layer in each IC on the wafer 1 can be formed to have a uniform thickness and a desired shape.

Furthermore, according to the wafer plating apparatus of the present invention, the above-described wafer plating method can be carried out using simple and low-cost equipment.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view showing the overall configuration of an embodiment of the wafer plating apparatus of the present invention, FIG. 2(a) is a cross-sectional front view of the same apparatus, and FIG. Figure 3(a)
, (b) and (c) are cross-sectional views showing the process of forming a hump on an integrated circuit by plating;
Figures a) and (b) each show a conventional example. l Plating unit 2 Plating tank 3, housing 4: Cylindrical body 4a H mouth surface 5 Wafer mounting plate 6, positive electrode 9. Negative electrode lO4 plating jetting vibe 12 Flowmeter 13, @ ring pump

Claims (4)

[Claims] (1) Prepare a cylindrical body having an opening at one end that almost matches the front shape of the wafer, connect the wafer placed at one end of the cylindrical body to a negative electrode, and connect the wafer to the other end of the cylindrical body. A wafer plating method characterized by leaving a wafer in a plating solution for a predetermined period of time with a positive electrode. (2) A method for plating a wafer according to claim 1, characterized in that a jet of the plating solution is formed substantially parallel to the surface of the wafer or its periphery. (3) A wafer plating device installed in a plating solution for forming a plating layer on the surface of the wafer, which comprises a cylindrical body having an opening at one end that substantially matches the front shape of the wafer, and the cylindrical body. A wafer fixing means provided on one end of the cylindrical body, a means for using the wafer fixed to the same as a negative electrode, and a positive electrode provided on the other end of the cylindrical body. Wafer plating equipment featuring: (4) The wafer plating apparatus according to claim 3, further comprising a means for spouting a plating solution onto the surface of the wafer fixed to the wafer fixing means or the periphery thereof.