JPH08111393A - Plating of semiconductor wafer - Google Patents

Abstract

PURPOSE: To provide a wafer plating method wherein a resist treatment process on the back and end surfaces sharply lowering an yield of a semiconductor wafer is abolished still also generating no diversity of bump sizes in a wet plating method forming bumps on the semiconductor wader surface in plating liquid. CONSTITUTION: A semiconductor wafer 2 is set on a plating jig body 1 keeping its surface upward and adapting to a groove 1a followed by applying a seal member 3 extending over an outer periphery of the wafer 2 and the jig body 1 as well as curing, then bump plating work is performed so as to peel the sealing member 3 after its finishing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet plating method for forming bumps (protruding electrodes) on the surface of a semiconductor wafer (hereinafter simply referred to as "wafer") in a plating solution. It relates to a jig.

[0002]

2. Description of the Related Art Conventionally, in a wet plating method for forming bumps on a wafer surface in a plating solution, the surface of the wafer excluding the plating surface, that is, the back surface and the end surface (outer peripheral side surface) of the wafer are coated with a resist. After that, the wafer is mounted on a plating jig to prevent the plating solution from coming into contact with the back surface and the end surface.

Further, as disclosed in Japanese Patent Application Laid-Open No. 5-247692, the wafer is sandwiched by two members described later through packing for the purpose of eliminating the resist previously coated on the back surface and the end surface of the wafer. There is also a way to do it.

Hereinafter, the conventional method for plating a wafer will be described with reference to the drawings. FIG. 2 is a cross-sectional view of an essential part of a wafer plating jig representing a conventional technique, and FIG. 3 is a cross-sectional view of an essential part of another wafer plating jig representing a conventional technique. In FIG. 2, 12 is a wafer, and 11 is a plating jig main body made of a resin material for positioning and holding the wafer 12. Thirteen
Is a plating resist, and 14 is an electrode rod for wiring a current from an external power source and passing a current through the wafer.

In the method of FIG. 2, the wafer 12 is previously prepared.
The surface of the plating resist 1 is held down on a rotating jig.
Wafer 12 after curing (drying) after dropping 3 liquids
The back surface and the end surface of the are coated with the plating resist 13. A predetermined portion of the surface of the wafer 12 is pressed by the electrode rod 14 and set on the jig body 11, and then the plating jig is held in a plating solution for plating. As shown by the arrow in FIG. 2, since the plating is performed in the uniform flow of the plating solution, bumps having a uniform plating thickness can be obtained. The portion covered with the resist 13 is not plated because the plating solution does not come into contact with it. The resist 13 is stripped after the plating operation is completed.

In FIG. 3, 22 is a wafer, 21 is a lower member which is a main body of a plating jig for positioning and holding the wafer 22, 25 is a packing, 23 is an upper member for fixing the packing 25, and 26 is an upper member. A clamper, which is a stopper for sandwiching 23 and the lower member 21, is an electrode rod. In the method of FIG. 3, the wafer 22 is sandwiched between the lower member 21 and the upper member 23 via the packing 25, and is fixed by the clamper 26. After the electrode rod 24 is applied to a predetermined place on the surface of the wafer 22, this plating jig is held in the plating solution. In this case, the flow of the plating solution is the wafer 22 as shown by the arrow.
Disturbance occurs around the packing 25 fixing portion on the outer peripheral portion, resulting in a spiral state. Since the plating solution is blocked by the packing 25, it does not come into contact with the back surface and the end surface of the wafer 22.

[0007]

However, in the conventional plating method as described above, the following problems occur in the back surface and end face resist coating steps. (B) Scratches on the wafer surface due to holding the wafer surface in the back surface resist coating process. (B) In the resist solution curing process, the heating temperature is low, the curing time is short due to a short heating time, the heating temperature is too high, and the heating time is too long. It may cause defects.

Further, in the method of holding the wafer through the packing by the two members, the thickness of the upper member is increased in order to secure the rigidity of the upper member which is the fixing side of the packing in the jig structure. As a result, the flow of the plating solution becomes irregular, and there is a concern that there will be large variations in the bump dimensions within the wafer. All of the above defects occur in a process close to the final process in semiconductor manufacturing, and the amount of loss is very large.

In view of the above, the present invention eliminates the resist processing steps on the back surface and the end surface, which significantly reduce the yield of wafers in order to solve the above problems, and further, the method of plating a wafer in which the variation in the bump size does not occur. The purpose is to provide.

[0010]

In order to achieve the above object, the present invention mounts a wafer on a plating jig having a holding member for holding the wafer and an electrode in contact with the surface of the wafer, and plating A method of plating a semiconductor wafer in which electroplating is performed in a liquid, characterized in that a sealing member is applied over the entire circumference of the wafer across the wafer surface and the holding member.

Further, the sealing member has not only a sealing property for preventing the contact of the plating solution with the surface other than the plated surface of the wafer, but also chemical resistance and heat resistance, which can be easily peeled off after the plating operation is completed. And

An annular groove having an outer diameter larger than the outer diameter of the wafer and an inner diameter smaller than the outer diameter of the wafer is formed in the wafer holding member.

[0013]

According to the present invention, since the outer peripheral portion of the wafer is covered with the seal member and the plating solution does not come into contact with the back surface and the end surface of the wafer, the resist processing on the back surface and the end surface of the wafer becomes unnecessary, and the seal member is applied. Since the thickness is not thick, there is no irregular flow of the plating solution on the outer peripheral portion of the wafer.

[0014]

An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a cross-sectional view of an essential part showing an embodiment of the present invention. In FIG. 1, reference numeral 1 is a plating jig body which is a holding member made of a vinyl chloride resin material for holding a wafer, and 2
Is a wafer, 3 is a sealing member, and 4 is an electrode rod similar to the conventional one.

An annular groove 1a having an outer diameter larger than the outer diameter of the wafer 2 and an inner diameter smaller than the outer diameter of the wafer 2 is provided on the upper surface of the plating jig body 1. The plating jig body 1 inside the groove 1a is arranged so that the upper surface of the plating jig body 1 outside the groove 1a and the upper surface of the wafer are substantially flush with each other.
The height of the upper surface of is set. On the lower surface of the wafer 2, a hook 1b used to hold the plating jig in the plating solution.
Has been fixed. S is the plating jig body 1 and the wafer 2
Therefore, the gap S is set to be small. Even if the gap S becomes large due to dimensional accuracy or the like and the seal member 3 enters the groove 1a, the groove 1a serves as a staying place for the seal member 3 and therefore flows into the back surface of the wafer 2 to complete the plating operation. It is possible to prevent the separation of the plating jig body 1 and the wafer 2 from becoming difficult later.

A method of performing plating using this plating jig will be described. After placing the wafer 2 on the jig body 1 with the surface of the wafer 2 facing upward so that the outer circumference of the wafer is on the groove 1a of the plating jig body 1, the seal member 3 is interrupted along the gap S. Apply without. H represents the coating width of the seal member 3 from the outer peripheral edge of the wafer. The narrower the coating width H is, the larger the number of IC chips to be taken per wafer is. However, in this embodiment, about 1 mm is sufficient. After that, the seal member 3 is cured. The curing condition is 120 ° C to 130 ° C,
Heat for about 30 minutes. If curing is performed with the seal member 3 flowing into the back surface of the wafer 2, the wafer 2 and the plating jig main body 1 will be adhered, making it difficult to remove the wafer 2 after the plating operation is completed. Since the 2 is cracked, the clearance 1a is required in the plating jig body 1.

After the sealing member 3 curing step, the electrode rod 4 is attached to the plating jig, and is held in the plating solution by the hook 1b to perform bump plating. Since the swelling of the seal member 3 from the surface of the wafer 2 is small, the flow of the plating solution is rectified along the surface of the wafer 2 as indicated by the arrow, and plating is performed under uniform conditions within the wafer.

When the plating process is completed, the wafer 2
The plating jig body 1 is cleaned with the electrode rod 4 attached, and then the electrode rod 4 is removed, the seal member 3 is peeled off, and the plated wafer 2 is taken out from the plating jig body 1.

Therefore, as described above, the sealing member must satisfy the following conditions. Sealing property The plating solution does not flow into the back and end faces of the wafer. Chemical resistance, plating resistance, etc. Ease of peeling Peeling is easy after plating. Heat resistance Gold bumps have a plating solution temperature of 6
Around 0 ° C. As a material satisfying the above conditions, for example, “Hakuri type heat-resistant masking material # 448T” manufactured by Asahi Chemical Research Institute, “Solder Shield SSZ-10” manufactured by Taiyo Ink Mfg. Co., Ltd.
0SC ”and so on.

As a coating method of the seal member, there is a screen printing method and the like, but a coating method using a dispenser which does not apply stress to the wafer is most preferable.

[0021]

According to the plating method of the present invention, the plating jig having a structure in which the outer periphery of the wafer and the holding jig are covered with the seal member does not require resist treatment on the back surface and the end surface of the wafer. Not only is it possible to perform plating without variations in bump size. In addition, since the seal member is made of a material that has not only sealability but also chemical resistance, heat resistance, and easy peeling, the wafer can be easily peeled after plating because it can withstand the plating treatment. It will not be damaged. Therefore, it is possible to provide a method of plating a wafer, which has good workability and can obtain high-quality bumps.

[Brief description of drawings]

FIG. 1 is a sectional view of a plating jig used in a plating method according to an embodiment of the present invention.

FIG. 2 is a sectional view of an essential part of a plating jig representing a conventional technique.

FIG. 3 is a cross-sectional view of an essential part showing another conventional technique.

[Explanation of symbols]

 1 Plating jig body 1a Groove 2 Semiconductor wafer 3 Sealing member 4 Electrode rod

Claims (3)

[Claims] 1. A method for plating a semiconductor wafer, wherein a semiconductor wafer is mounted on a plating jig having a holding member for holding the semiconductor wafer and an electrode rod in contact with the surface of the semiconductor wafer, and electroplating is performed. A method of plating a semiconductor wafer, characterized in that the semiconductor wafer is applied over the entire surface of the semiconductor wafer so as to extend over the surface portion of the semiconductor wafer and the holding member. 2. The sealing member has chemical resistance and heat resistance as well as a sealing property for preventing contact of a plating solution with a surface other than the plated surface of the semiconductor wafer, and can be easily peeled off after completion of plating operation. The method for plating a semiconductor wafer according to claim 1, wherein the method has a peeling property. 3. The holding member is formed with an annular groove having an outer diameter larger than the outer diameter of the semiconductor wafer and an inner diameter smaller than the semiconductor wafer. Semiconductor wafer plating method.