Method of manufacturing semiconductor device

Semiconductor device manufacturing: process – Chemical etching – Vapor phase etching

Reexamination Certificate

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C438S689000, C438S704000

Reexamination Certificate

active

06429138

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor device in which a wire is bonded to a bonding pad of an interconnection.
2. Description of the Related Art
Along with micropatterning and high-density integration of semiconductor devices, interconnections are also micropatterned and multilayered. However, micropatterning and multilayering interconnections decrease electromigration resistance and stress migration resistance. To avoid this, an aluminum-copper alloy is being used as a material of an interconnection instead of pure aluminum or an aluminum-silicon alloy which has conventionally been used.
One related art of a method of manufacturing a semiconductor device in which a gold wire is bonded to a bonding pad of an aluminum-copper alloy interconnection will be described with reference to
FIGS. 1A
to
2
B. In this related art, as shown in
FIG. 1A
, an aluminum-copper alloy interconnection
12
having a bonding pad
12
a
is formed on an interlayer insulating film
11
on a semiconductor base (not shown). An insulating film
13
such as an SiO2 film is deposited by CVD to cover the interconnection
12
.
As shown in
FIG. 1B
, a photoresist film
14
is applied to the insulating film
13
, and an opening
14
a
is formed in the photoresist film
14
above the bonding pad
12
a
by photolithography. As shown in
FIG. 1C
, an opening
13
a
is formed in the insulating film
13
by etching using CFX-based reaction gas and the photoresist film
14
as a mask.
To vertically etch the insulating film
13
in forming the opening
13
a
, anisotropic etching is employed to form an organic polymer film
15
and metal polymer film
16
on the inner side surface of the opening
13
a
during etching, and to progress etching using the organic polymer film
15
and metal polymer film
16
as a mask.
The organic polymer film
15
is made of a reaction product upon reaction between the reaction gas and the materials of the photoresist film
14
and insulating film
13
, contains many organic components, and is formed before the interconnection
12
is exposed. The metal polymer film
16
is made of a reaction product upon reaction among the reaction gas, the aluminum-copper alloy and the materials of the photoresist film
14
and insulating film
13
, contains many metal components, and is formed after the interconnection
12
is exposed.
Even when the photoresist film
14
is removed with an organic solvent while the organic polymer film
15
and metal polymer film
16
are kept formed, they are not removed. The organic polymer film
15
and metal polymer film
16
are left on the inner side surface of the opening
13
a
or scattered onto the bonding pad
12
a.
If a gold wire is bonded to the bonding pad
12
a
in this state, the bonded gold wire easily peels off because the organic polymer film
15
and metal polymer film
16
left on the inner side surface of the opening
13
a
decrease the bonding area or the organic polymer film
15
and metal polymer film
16
scattered onto the bonding pad
12
a
interfere with bonding.
In this related art, therefore, the photoresist film
14
in the state of
FIG. 1C
is removed by a predetermined thickness with the oxygen plasma. Then, as shown in
FIG. 1D
, the remaining photoresist film
14
and metal polymer film
16
are removed with an amine-based organic solvent. As shown in
FIG. 2A
, the organic polymer film
15
is removed with the oxygen plasma. As shown in
FIG. 2B
, a gold wire
18
is bonded to the bonding pad
12
a
via a gold wire bond
17
.
In the above related art, however, since the photoresist film
14
is removed by a predetermined thickness with the oxygen plasma, and then the remaining photoresist film
14
and metal polymer film
16
are removed with the amine-based organic solvent, an aluminum oxide film has already been formed on the surface of the bonding pad
12
a
in removal with the amine-based organic solvent.
The aluminum oxide film functions as a mask against the amine-based organic solvent. Even by removal with the amine-based organic solvent, the aluminum oxide film remains on the surface of the bonding pad
12
a
, and the surface of the bonding pad
12
a
is kept smooth. In addition, along with micropatterning and high-density integration of semiconductor devices, the area of the bonding pad
12
a
and the diameter of the gold wire bond
17
are decreased.
For this reason, in this related art, the gold wire
18
bonded to the bonding pad
12
a
easily peels off. Therefore, the semiconductor device cannot be manufactured with a high yield. In addition, the area of the bonding pad
12
a
and the diameter of the gold wire bond
17
are difficult to decrease, and a fine semiconductor device having a high integration degree cannot be manufactured.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a semiconductor device manufacturing method capable of preventing peeling of a wire bonded to a bonding pad of an interconnection to allow the manufacture of a semiconductor device with a high yield and to decrease the area of the bonding pad and the diameter of a wire bond to allow the manufacture of a fine semiconductor device having a high integration degree.
In the semiconductor device manufacturing method according to the present invention, a metal polymer film formed on the inner side surface of the opening of an insulating film by anisotropic etching of the insulating film is removed with an amino group (NH
2
—) in an amine-based organic solvent, while a photoresist film is removed with the organic solvent component in the amine-based organic solvent. This removal with the amine-based organic solvent is performed subsequent to anisotropic etching of the insulating film.
As a result, the bonding pad of an interconnection is free from any oxygen plasma processing till removal with the amine-based organic solvent after the bonding pad is exposed in the opening of the insulating film by anisotropic etching of the insulating film. No aluminum oxide film is formed on the surface of the bonding pad of the interconnection in removal with the amine-based organic solvent.
Along with removal using the amine-based organic solvent, the amino group (NH
2
—) in the amine-based organic solvent enters the interface between aluminum and copper of an aluminum-copper alloy in the bonding pad, and highly ionizable aluminum elutes. As the elution progresses, copper crystal grains come out of the aluminum-copper alloy to form pores in the surface of the bonding pad upon removal.
An organic polymer film formed on the inner side surface of the opening of the insulating film by anisotropic etching of the insulating film is also removed with the oxygen plasma, and then a wire is bonded to the bonding pad. In bonding, no metal polymer film or organic polymer film exists on the bonding pad.
More specifically, since no metal polymer film or organic polymer film exists on the bonding pad in bonding, the metal polymer film and organic polymer film do not decrease the bonding area or interfere with bonding. In bonding, since pores are formed in the surface of the bonding pad, the material of the wire bond enters these pores. Therefore, the wire bonded to the bonding pad of the interconnection hardly peels off.
Since the wire bonded to the bonding pad of the interconnection hardly peels off, the semiconductor device can be manufactured with a high yield, and the area of the bonding pad and the diameter of the wire bond can be decreased to manufacture a fine semiconductor device having a high integration degree.
In a preferred semiconductor device manufacturing method according to the present invention, the time for removing, with the oxygen plasma, the organic polymer film formed on the inner side surface of the opening of the insulating film by anisotropic etching of the insulating film is set to 10 to 40 min. The organic polymer film can be satisfactorily removed, while formation of the aluminum oxide film on the surface of the bondin

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