JPH0465832A - Manufacturing of semiconductor device - Google Patents

Abstract

PURPOSE:To control the progress of corrosion etching of a barrier metal by packing a metal constituting a bump or a wiring electrode in the depressed part of a semiconductor after making grow it due to plating, and then by accumulating the third metal layer on the front side after removing a resist. CONSTITUTION:A bump metal 7 is packed in the depressed part to form a bump surrounded by a resist 6 by electrolytic plating. Then, the resist 6 is removed, and the third metal layer 8 is accumulated on the front side. In a barrier metal consisting of the third metal layer 8, the second metal layer 5, and the first metal layer 4, the unnecessary part of the barrier metal except for the bump is removed by etching. As a result, the bump is formed on an electrode pad 2. In other words, the bump metal 7 is covered by the third metal layer 8. In this way, the second metal layer 5 and the bump metal layer 7, which constitute the barrier metal, are not directly contacted in the plating liquid. Therefore, 'battery effect' does not generate between the second metal player 5 and the bump metal layer, thereby there is no fear that the barrier metal may be corroded.

Description

[Detailed Description of the Invention] [Summary] Regarding the method of forming bumps and the method of forming wiring electrodes, the purpose of the method of forming bumps is to prevent the barrier metal under the bumps and wiring electrodes from being eroded during etching. , a method for forming bumps by plating metal on a large number of electrode pads formed on a wafer, in which a large number of electrode pads formed on a wafer are covered with an insulating cover film; a first metal layer for preventing mutual diffusion between the metal constituting the electrode pad and the metal constituting the bump or wiring electrode, and the first metal layer is formed on the entire surface of the wafer. A step of forming a barrier metal by continuously depositing a second metal layer to strengthen the adhesion between the layer and the bump or wiring electrode, a step of coating the entire surface with resist, and a photolithography technique are used to form the bump or wiring electrode. a step of removing the resist from a portion where a wiring electrode is to be formed to form a recess; a step of plating and growing a metal constituting the bump or wiring electrode in the recess by electroplating; a step of removing a third metal layer; a step of depositing a third metal layer over the entire surface; and a step of depositing a third metal layer on the entire surface.

and a step of removing unnecessary portions other than the bumps from the barrier metal made of the second metal layer and the first metal layer by etching.

The wiring electrode is formed by plating metal on a base wiring layer formed in large numbers on a wafer.

A large number of underlying wiring layers formed on a wafer are covered with an insulating cover film! A step of opening a pole number extraction portion, and a first metal layer for preventing interdiffusion between the metal constituting the base wiring layer and the metal constituting the bump or wiring electrode on the entire surface of the wafer.

and a step of continuously depositing a second metal layer to strengthen the adhesion between the first metal layer and the bump or wiring electrode to form a barrier metal, a step of applying a resist to the entire surface, and a step of photolithography. A step of removing the resist at the portion where the bump or wiring electrode is to be formed to form a recess using a technique.

a step of growing and filling the recess with metal constituting the bump or wiring electrode by electroplating;
a step of removing the resist, a step of depositing a third metal layer on the entire surface, and unnecessary portions other than the wiring electrodes of the barrier metal consisting of the third metal layer, the second metal layer, and the first metal layer. and removing by etching.

C. Industrial Application Field] The present invention relates to a method for manufacturing a semiconductor device, and particularly to a method for forming bumps and a method for forming wiring electrodes.

In recent years, semiconductor integrated circuit devices have become faster.

As higher density is required, T A B (T
There is a tendency for the use of the apeAuto+*ated Bonding) method to increase.

For this reason, there is an increasing demand for higher density of bumps formed on semiconductor wafers, and the bump pitch is becoming narrower.

It is also desired to reduce the pinch of wiring formed by plating on a semiconductor wafer.

[Conventional technology]

FIG. 9 to FIG. 15 are diagrams showing each step of a conventional bump forming method.

The steps will be explained below in order.

(Step 1. See FIG. 9) A wiring layer including a large number of electrode pads 12 formed on the wafer 11 is covered with an insulating cover film 13, and the electrode pad portions are opened.

(Step 2. See FIG. 10) A first metal layer 14 is formed on the entire surface to prevent mutual diffusion between the metal forming the electrode pad 12 and the metal forming the bump.
Deposit.

(Step 3. See FIG. 11) A second metal layer 15 is deposited on the entire surface to strengthen the adhesion between the first metal layer 14 and the bumps.

The first metal layer 14 and the second metal layer 15 constitute a barrier metal.

(Step 4. See Figure 12) A resist 16 is applied to the entire surface.

Using photolithography, the resist 16 in the portion where the bump is to be formed is removed to form a recess.

(Step 5, see FIG. 13) The bump metal 17 is grown and filled in the recess by electroplating.

(Step 6. See Figure 14) The resist 16 is removed.

(Step 7, see FIG. 15) Of the barrier metal made up of the second metal layer 15 and the first metal layer 14, unnecessary portions other than the bumps 17 are removed by etching.

Through the above steps, bumps 17 are formed on the electrode pads 12 provided on the wafer.

[Problem to be solved by the invention]

Usually, the second metal layer 15 constituting the barrier metal is made of PT.
For the bump metal 17, Au is used.

Then, in the above step 7 (FIG. 15).

Wet etching is used to remove unnecessary portions of the barrier metal consisting of the second metal layer 15 and the first metal layer 14 other than the bumps 17 by etching.

In that case, the second metal layer 15 is in direct contact with the bump metal 17, so during wet etching.

Due to the difference in ionization tendency between the metal constituting the second metal layer 15 and the bump metal 17, a "battery effect" occurs, and as shown by A in FIG. 15/Etching progresses to erode the first metal layer 14).

When the barrier metal becomes severely eroded, the electrode pads 12 provided on the wafer 11 are etched.
A problem arises in that it becomes completely useless as a bump.

One possible solution to this problem is to extend the cover film 13 to a range where the etching that erodes the barrier metal does not reach the electrode pads 12. However, with this method, the electrode pads cannot be formed small and the pinch between the electrode pads cannot be narrowed.

In other words, increasing the density of bumps is inhibited. A new problem arises.

The present invention solves the above problems and prevents the barrier metal under the bumps and wiring electrodes from being eroded during etching. It is an object of the present invention to provide a method for manufacturing a semiconductor device, particularly a method for forming bumps and a method for forming wiring electrodes.

[Means to solve the problem]

In order to achieve the above object, a method for manufacturing a semiconductor manufacturing apparatus according to the present invention is configured as follows.

(Bump formation method) In a bump formation method in which a large number of electrode pads formed on a wafer are plated with metal, a large number of electrode pads formed on a wafer are covered with an insulating cover film. a first metal layer for preventing mutual diffusion between the metal constituting the electrode pad and the metal constituting the bump or wiring electrode; a step of continuously depositing a second metal layer to strengthen the adhesion between the first metal layer and the nozzle or wiring electrode to form a barrier metal;
A step of applying resist to the entire surface, a step of removing the resist in the area where the bump or wiring electrode is to be formed using photolithography to form a recess, and a step of forming the bump or wiring electrode in the recess using an electroplating method. a step of plating and growing and filling a constituent metal, a step of removing the resist, a step of depositing a third metal layer on the entire surface, and a step of depositing a third metal layer, a second metal layer, and a first metal layer. The structure includes a step of removing unnecessary portions other than the bumps from the barrier metal formed by etching.

(Method for Forming Wiring Electrodes) In the method for forming wiring electrodes, which are formed by plating metal on the underlying wiring layers formed in large numbers on the wafer, the underlying wiring layers formed in large numbers on the wafer are insulated. covered with a cover membrane.

a step of opening an electrode extraction portion, and a first metal layer for preventing interdiffusion between the metal constituting the underlying wiring layer and the metal constituting the bump or wiring electrode, and the first metal on the entire surface of the wafer. A step of continuously depositing a second metal layer to strengthen the adhesion between the layer and the bump or wiring electrode to form a barrier metal, and a step of applying a resist over the entire surface.

A process of removing the resist in areas where bumps or wiring electrodes are to be formed to form recesses using photolithography, and an electrolytic plating process.

a step of growing and filling a metal constituting a bump or a wiring electrode in the recess, a step of removing the resist, a step of depositing a third metal layer on the entire surface, and a step of depositing a third metal layer on the entire surface;
The method is configured to include a step of removing unnecessary portions other than the wiring electrodes by etching out of the barrier metal consisting of the metal layer and the second metal layer and the first metal layer.

[For production]

A method for manufacturing a semiconductor device according to the present invention will be explained with reference to FIGS. 1 to 8, which show an embodiment of the method for manufacturing a semiconductor device according to the present invention.

Although the following description deals with bumps formed on electrode pads provided on a wafer, the same applies to wiring electrodes formed on a base wiring layer provided on a wafer.

1) Process 1. A wiring layer including a large number of electrode pads 2 formed on a wafer 1 (see FIG. 1) is covered with an insulating cover film 3, and the electrode pad portions are opened.

2) Process 2. Referring to FIG. 2, a first metal layer 4 is deposited on the entire surface of the wafer to prevent mutual diffusion between the metal forming the electrode pad 2 and the metal forming the bump.

3) Process 3. Referring to FIG. 3, a second metal layer 5 is deposited on the entire surface to strengthen the adhesion between the first metal layer 4 and the bumps.

The first metal layer 4 and the second metal layer 5 constitute a barrier metal.

4) Process 4. Referring to FIG. 4, after applying a resist 6 to the entire surface, the resist 6 is removed from a portion where a bump is to be formed to form a recessed portion using a photolithography technique.

5) Process 5. Referring to FIG. 5, a recess surrounded by a resist 6 in which a bump is to be formed is filled with bump metal 7 by electroplating.

6) Process 6. See Figure 6 Remove resist 6.

7) Process 7. See Figure 7 A third metal layer 8 is deposited over the entire surface.

8) Process 8. See FIG. 8. Third metal layer 8. and second metal layer 5 and first metal layer 4
Unnecessary parts other than the bumps are removed by etching from the barrier metal made of .

Through the above steps, bumps are formed on the electrode pads 2.

In the method for manufacturing a semiconductor device according to the present invention, step 7 (seventh
In the figure), the bump metal 7 is covered with a third metal layer 8. By doing this, in step 8,
When wet etching the barrier metal, the second metal layer 5 and the bump metal 7 constituting the barrier metal do not come into direct contact in the plating solution, so the second metal layer 5 and the bump metal 7 do not come into direct contact with each other in the plating solution as in the conventional example. 7, a "battery effect" will not occur, and the barrier metal will not be eroded.

[Embodiment] FIGS. 1 to 8 are diagrams showing each step of an embodiment of the method for manufacturing a semiconductor device according to the present invention.

Although the following description deals with bumps formed on electrode pads provided on a wafer, the same applies to wiring electrodes formed on a base wiring layer provided on a wafer.

1) Process 1. A large number of them were formed on the wafer 1 shown in FIG. The wiring layer including the aluminum electrode pad 2 is made of PSG, for example.

513N4. It is covered with an insulating cover film 3 made of polyimide or the like, and the l-pole pad portion is opened.

2) Process 2. Referring to FIG. 2, a first metal layer 4 made of Ti, Cr, etc. is deposited on the entire surface of the wafer 1 in order to prevent mutual diffusion between aluminum forming the electrode pad 2 and Au forming the bump.

3) Process 3. Referring to FIG. 3, a second metal layer 5 made of Pt, Pd, etc. is deposited on the entire surface in order to strengthen the adhesion between the first metal layer 4 and the Au bumps.

The first metal layer 4 and the second metal layer 5 constitute a barrier metal.

4) Process 4. Referring to FIG. 4, after applying a resist 6 to the entire surface, the resist 6 is removed from a portion where a bump is to be formed to form a recessed portion using a photolithography technique.

5) Process 5. Referring to FIG. 5, a concave portion in which a bump is to be formed, surrounded by a resist 6, is filled with AU as a bump metal 7 using l-field coating.

6) Process 6. See Figure 6 Remove resist 6.

7) Process 7. Refer to Figure 7, the entire surface is coated with Au as the plating metal 7 and heated at 350°C to 40°C.
1, such as Sn, which reacts during ILB (inner lead bonding) performed by heating to 0°C.

The third metal layer 8 made of Cu, Ni, etc. is formed by electroless plating, field plating, vapor deposition, sputtering, etc.
accumulate.

8) Process 8. See FIG. 8. Third metal layer 8. and second metal layer 5 and first metal layer 4
Unnecessary parts other than the bumps of the barrier metal made of are removed by wet etching.

After each of the above steps, A is placed on the aluminum electrode pad 2.
A u-bump 7 is formed.

In the method for manufacturing a semiconductor device of this embodiment, in step 7 (FIG. 7), a reaction occurs with the Au bumps 7 during ILB. Sn
The third metal layer 8 is made of a metal such as , Cu, or Ni. By doing this, when wet-etching the barrier metal in step 8 (FIG. 8), the second metal layer 5 constituting the barrier metal and the Au bumps 7 will not come into direct contact in the plating solution. 2. A "battery effect" occurs between the metal layer 5 and the Au bump 7.

This prevents the barrier metal from being eroded.

Since the third metal layer 8 covering the bump gold 1i7 uses a metal that reacts with the bump metal 7 at the heating temperature during ILB, it is possible to easily bond the bump 7 and the inner lead in the ILB process. .

〔Effect of the invention〕

According to the present invention, wet etching of the barrier metal can be performed without direct contact between the bump or the wiring electrode and the barrier metal, so that erosion and etching of the barrier metal at the lower part of the bump or the lower part of the wiring electrode can be prevented. Can be suppressed.

As a result, it becomes possible to reduce the bump size and the bump pitch, and also to reduce the width of the wiring electrode and the wiring pitch.

It is possible to increase the density of semiconductor integrated circuit devices.

[Brief explanation of drawings]

1 to 8 are diagrams showing each step of a manufacturing method according to an embodiment of the present invention, and FIGS. 9 to 15 are diagrams showing each step of a conventional example. 1 to 8, 1: wafer 2: electrode pad 3: cover film 4: first metal layer 5: second metal layer 6: resist 7: bump metal 8: third metal layer

Claims (2)

[Claims] (1) In a bump formation method in which a large number of electrode pads formed on a wafer are plated with metal, a wiring layer including a large number of electrode pads formed on a wafer is covered with an insulating cover film. a step of covering the wafer with a metal wafer and opening an electrode pad portion;
A step of successively depositing a metal layer and a second metal layer for strengthening the adhesion between the first metal layer and the bump to form a barrier metal, a step of applying a resist over the entire surface, and photolithography. a step of removing the resist in the area where the bump is to be formed to form a recess using a technique; a step of plating and growing bump metal into the recess using an electroplating method; and a step of removing the resist. , a step of depositing a third metal layer on the entire surface, and a step of removing unnecessary portions other than the bumps from the third metal layer, the barrier metal consisting of the second metal layer, and the first metal layer by etching. A method of manufacturing a semiconductor device, comprising: (2) In a method for forming wiring electrodes in which a large number of underlying wiring layers formed on a wafer are plated with metal, the underlying wiring layers formed in large numbers on a wafer are covered with an insulating cover film. a first metal layer for preventing interdiffusion between the metal constituting the underlying wiring layer and the metal constituting the wiring electrode; The process of forming a barrier metal by continuously depositing a second metal layer to strengthen the adhesion between the metal layer and the wiring electrode, the process of coating the entire surface with resist, and the process of forming the wiring electrode using photolithography technology. a step of removing the resist in a portion to be formed to form a recess; a step of growing and filling the recess with a metal constituting the wiring electrode by electroplating; and a step of removing the resist. a step of depositing a third metal layer on the entire surface; and a step of removing by etching unnecessary portions other than the wiring electrodes of the barrier metal consisting of the third metal layer, the second metal layer, and the first metal layer. A method of manufacturing a semiconductor device, comprising: