Method for fixing a semiconductor device having stud bumps...

Semiconductor device manufacturing: process – Packaging or treatment of packaged semiconductor – Including adhesive bonding step

Reexamination Certificate

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Details

C438S124000, C438S108000

Reexamination Certificate

active

06420213

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a method for mounting a semiconductor device and, more particularly, to a method for fixing a semiconductor device having stud bumps to a mounting substrate by using an adhesive.
Recently, in order to reduce a mounting area of a mounting substrate to satisfy the demand of miniaturizing electronic equipment, semiconductor devices are reduced in their size and, thus, the pitches of their terminals are reduced. As a means of reducing the mounting area, there is a flip-chip mounting method to mount a bare chip on a mounting surface. In the flip-chip mounting method, the bare chip is generally fixed to the mounting substrate by an adhesive.
2. Description of the Related Art
There are the following two methods to apply an adhesive for mounting a semiconductor device in the flip-chip mounting method.
1) A semiconductor device is mounted to a mounting substrate after an adhesive is applied to the mounting substrate.
2) An adhesive is applied between a mounting substrate and a semiconductor device after the semiconductor device is mounted on the mounting substrate.
FIG. 1
is a flowchart of a mounting process for mounting a semiconductor device by using the above-mentioned method 1).
FIG. 2
is an illustration for explaining the mounting process shown in FIG.
1
.
In the mounting process shown in
FIG. 1
, after stud bumps
2
are formed on a semiconductor device
1
, the stud bumps
2
are subjected to leveling so as to equalize the height of the stud bumps
2
. The leveling is performed by pressing the stud bumps
2
against a hard material plate
3
such as a ceramics plate.
That is, as shown in FIG.
2
-(a), the semiconductor device
1
having the stud bumps
2
is held by a tool
4
(step S
1
of FIG.
2
), and, then, the stud bumps
2
are pressed against the hard material plate
3
. At this time, an electrically conductive adhesive
5
is previously applied to the hard material plate
3
so that the electrically conductive adhesive
5
is transferred to the stud bumps
2
during the leveling process (step S
2
).
Thereafter, the position recognition of the semiconductor mounting area of the mounting substrate
6
is performed (step S
3
). Then, as shown in FIG.
2
-(b), an electrically non-conductive adhesive
7
is applied to the semiconductor mounting area of the mounting substrate
6
(step S
4
). The electrically non-conductive adhesive
7
is supplied so as to fill a space between the mounting surface of the semiconductor device
1
and the mounting substrate
6
. That is, the electrically non-conductive adhesive
7
has the insulating property so as to protect the electrodes on the semiconductor device
1
and the mounting substrate
6
.
On the other hand, the electrically conductive adhesive
5
is supplied so as to connect the stud bumps
2
to the lands
6
a
of the mounting substrate
6
. Thus, the electrically conductive adhesive
5
provides a different function from the electrically non-conductive adhesive
7
. After the electrically non-conductive adhesive
7
is applied to the semiconductor mounting area of the mounting substrate
6
as shown in FIG.
2
-(c), the semiconductor device
1
is placed on the mounting substrate
6
as shown in FIG.
2
-(d) and the electrodes of the semiconductor device
1
are bonded to the lands
6
a
of the mounting substrate
6
by applying a heat (step S
5
). The non-conductive adhesive
7
is also cured by the heat provided to bond the stud bumps
2
.
FIG. 3
is a flowchart of a mounting process for mounting a semiconductor device by using the above-mentioned method 2).
FIG. 4
is an illustration for explaining the mounting process shown in FIG.
3
.
Similar to the method shown in
FIG. 1
, in the mounting process shown in
FIG. 3
, after the stud bumps
2
are formed on a semiconductor device
1
, the stud bumps
2
are subjected to leveling so as to equalize the height of the stud bumps
2
. The leveling is performed by pressing the stud bumps
2
against the hard material plate
3
such as a ceramics plate.
That is, as shown in FIG.
4
-(a), the semiconductor device
1
having the stud bumps
2
is held by a tool
4
(step S
11
of FIG.
3
), and, then, the stud bumps
2
are pressed against the hard material plate
3
. At this time, the electrically conductive adhesive
5
is previously applied to the hard material plate
3
so that the electrically conductive adhesive
5
is transferred to the stud bumps
2
during the leveling process (step S
12
).
Thereafter, as shown in FIG.
4
-(b), the position recognition of the semiconductor mounting area of the mounting substrate
6
is performed (step S
13
). Then, as shown in FIG.
4
-(c), the semiconductor device
1
is placed on the semiconductor mounting area of the mounting substrate
6
(step S
14
). In this state, the stud bumps
2
are electrically connected to the lands
6
a
of the mounting substrate
6
by the electrically conductive adhesive
5
on the stud bumps
2
.
Thereafter, as shown in FIG.
4
-(d), the electrically non-conductive adhesive
7
is supplied between the semiconductor
1
and the semiconductor substrate
6
(step S
15
).
In the above-mentioned mounting methods, the semiconductor device
1
is mounted to the mounting substrate
6
by the flip-chip mounting method by using the stud bumps
2
. In a state in which the stud bumps
2
are formed on the semiconductor device
1
, the height of the stud bumps
2
are not uniform. Accordingly, the leveling of the stud bumps
2
is performed so that all stud bumps
2
are put in contact with the respective lands
6
a
of the mounting substrate
6
. In the conventional methods, the electrically conductive adhesive
5
is applied to the stud bumps
2
at the same time when the leveling is performed. Then, the semiconductor substrate
1
is fixed to the mounting substrate
6
mainly by the non-conductive adhesive
7
.
As mentioned above, since the two kinds of adhesives, the electrically conductive adhesive and the electrically non-conductive adhesive, are used in the conventional flip-chip mounting method, the adhesives must be applied by the different processes which results in an increase in the number of processes. Accordingly, there is a problem in that the tact of the mounting process is long.
Additionally, there is a problem in that the electrically conductive adhesive is more expensive than the electrically non-conductive adhesive since the electrically conductive adhesive used for the conventional flip-chip mounting method is prepared by adding electrically conductive particles to an electrically non-conductive adhesive as a base.
Further, the facility cost of the semiconductor device mounting apparatus occupies a large weight in the entire facility cost relating with the flip-chip mounting. Accordingly, an increase in the manufacturing efficiency of the semiconductor device mounting apparatus greatly contributes the reduction in the manufacturing cost of the semiconductor device. In the flip-chip mounting method using the stud bumps, a thermosetting resin is used as the electrically non-conductive adhesive. Since the thermosetting resin takes a relatively long curing time such as 20 seconds to mount a single semiconductor device, there is a problem in that a manufacturing efficiency is not high.
SUMMARY OF THE INVENTION
It is a general object of the present invention to provide an improved and useful mounting method of a semiconductor device in which the above-mentioned problems are eliminated.
A more specific object of the present invention is to provide a mounting method of a semiconductor device, which reduces the number of processes and the cost for mounting the semiconductor device by reducing the number of kinds of adhesives necessary for mounting the semiconductor device.
In order to achieve the above-mentioned objects, there is provided according to one aspect of the present invention a method for mounting a semiconductor device having a plurality of stud bumps to a mounting substrate, the method compr

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