Production of semiconductor device

Details Production of semiconductor device Production of semiconductor device

1999-10-27

2001-03-20

Picardat, Kevin M. (Department: 2823)

Semiconductor device manufacturing: process

Coating with electrically or thermally conductive material

To form ohmic contact to semiconductive material

C438S106000, C438S613000

Reexamination Certificate

active

06204162

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of producing a semiconductor device having resin bumps, that serve as external connection terminals, formed integrally with a resin-sealed portion that seals a semiconductor chip, and a metal substrate applicable to the same.
2. Description of the Related Art
FIG. 1
is a sectional view showing a semiconductor device having external connection terminals formed by means of resin bumps that are formed integrally with a resin-sealed portion. In the drawing, reference numeral
10
denotes a semiconductor chip,
12
denotes a resin-sealed portion and
14
denotes an external connection terminal. The external connection terminals
14
are formed by providing metal films
18
to coat the resin bumps
16
formed to protrude from the bottom face of the resin-sealed portion
12
on the chip mounting face of the semiconductor device. Electrodes of the semiconductor chip
10
and the metal films
18
are electrically connected via bonding wires
20
. Reference numeral
22
denotes a resin that protects the back face of the semiconductor chip by preventing the bottom face of the semiconductor chip
10
from being exposed from the resin-sealed portion
12
.
FIG. 2
is a bottom view of the semiconductor device. The external connection terminals
14
are arranged at positions that surround the semiconductor chip
10
, with the metal film
18
of each of the external connection terminals
14
being electrically connected to the electrode of the semiconductor chip
10
by wire-bonding. When the semiconductor chip
10
and the metal film
18
of the external connection terminals
14
are connected directly with the bonding wire
20
, a wiring pattern for electrically connecting the external connection terminals and the bonding wires becomes unnecessary, and it is also unnecessary to secure a space for providing the wiring pattern, thus making it possible to reduce the size of the semiconductor device.
FIG.
3
(
a
) to FIG.
3
(
e
) show the method of producing the semiconductor device described above. First, a photo-resist is applied to the surface of a metal substrate
30
such as copper foil, exposed to light and developed, thereby to form a photo-resist pattern
32
with openings where the external connection terminals
14
are to be formed (FIG.
3
(
a
)). Then the metal substrate
30
is half-etched using the photo-resist pattern
32
as a mask to form a recess
34
(FIG.
3
(
b
)). The inner surface of the recess
34
is then coated with plating of palladium or the like to form a metal film
18
(FIG.
3
(
c
)). Then the semiconductor chip
10
is mounted on the metal substrate
30
via the chip fastening resin
22
, and the electrodes of the semiconductor chip
10
and the metal films
18
formed on the bottom faces of the recesses
34
are connected by wire-bonding (FIG.
3
(
d
)).
Then one side of the metal substrate
30
whereon the semiconductor chip
10
is mounted is sealed with a resin by a resin sealing apparatus. FIG.
3
(
e
) shows the condition of the semiconductor chip
10
sealed with the resin. The semiconductor device is obtained by dissolving and removing the metal substrate
30
by etching the semiconductor chip
10
sealed with the resin. There is another method of producing the semiconductor device in which the metal films
18
, the resin-sealed portion
12
and the like are formed in such a way as can be exfoliated from the metal substrate
30
, and the resin-sealed portion
12
is exfoliated from the metal substrate
30
thereby separating them after sealing with the resin.
The semiconductor device described above is characterized by the fact that the semiconductor device can be provided as a small size product. However, because the resin bump
16
is formed integrally with the resin-sealed portion
12
when sealed with the resin, it is necessary to form the recess
34
in the metal substrate
30
. Also because the bottom face of the recess
34
serves as a bonding pad, an area necessary for bonding must be secured on the bottom face of the recess
34
, thus making it impossible to arrange the external connection terminals
14
in a high density.
FIG.
4
(
a
) and FIG.
4
(
b
) are enlarged views of the arrangement of the connections between the external connection terminals
14
and the mounting substrate. In the semiconductor device of the prior art, a bonding pad for connecting the external connection terminals
14
to the mounting substrate is a rectangle measuring about 0.6×0.3 mm, with intervals of about 0.65 mm between terminals. The bonding pad for connecting the external connection terminal
14
has a rectangular shape because a certain amount of area is required for the bonding pad and because the bottom face of the recess
34
is required to have a certain amount of area in order to prevent a bonding tool or the bonding wire
20
from making contact with an edge of the recess
34
when the bonding tool advances toward the bottom face of the recess
34
. The recess
34
is also required to have a depth of about 0.3 mm in order to ensure the height of the external connection terminals
14
.
When a product having a multitude of pins is produced with the semiconductor device having resin bumps
16
that serve as external connection terminals
14
being formed integrally with the resin-sealed portion
12
that seals the semiconductor chip, layout of the external connection terminals
14
is limited in the connecting construction of the prior art, and it is difficult to effectively mount with high density.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a preferable method of producing the semiconductor device having a connection construction which enables it to more effectively make multiple-pin construction, and a metal substrate applicable to the method.
In order to achieve the object, according to the first aspect of the present invention, there is provided a method of producing the semiconductor device, which comprises the steps of:
forming a recess on one side of the metal substrate;
forming a metal film, made of a metal that is not dissolved by an etchant solution which dissolves the metal substrate, on the inner surface of the recess;
punch-pressing a region of the metal substrate, that corresponds to one region of the metal film, from the other side of the metal substrate so that the region of the metal film formed on the bottom face of the recess becomes substantially flush with said one side of the metal substrate, thereby to form a bonding pad from an extending portion of the metal film that extends from the bottom face of the recess over the surface of the metal substrate;
mounting a semiconductor chip on said one side of the metal substrate whereon the bonding pad is formed;
wire-bonding the electrodes of the semiconductor chip and the bonding pads;
sealing with resin said one side of the metal substrate that includes the semiconductor chip, the bonding wire and the metal film; and
dissolving and removing the metal substrate by etching, thereby to expose the metal film formed on the inner surface of the recess.
In the first aspect of the present invention, the region where the metal film formed on the bottom face of the recess is punch-pressed is preferably at a position near the portion where the semiconductor chip is mounted in the bottom face of the recess.
In the first aspect of the present invention, it is preferable to provide a photo-resist pattern wherein a portion of the metal substrate where the recess is to be formed is exposed, to form the recess by etching the metal substrate using the photo-resist pattern as a mask, and to form the metal film by plating the inner surface of the recess.
Furthermore, according to the second aspect of the present invention, there is provided a method of producing the semiconductor device, which comprises the steps of:
forming a recess on one side of the metal substrate;
forming a metal film, made of a metal, that is not dissolved by an etchant solution which dissolves the metal

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