Electronic component with anodically bonded contact

Details Electronic component with anodically bonded contact Electronic component with anodically bonded contact

2000-09-20

2001-10-30

Chaudhuri, Olik (Department: 2814)

Active solid-state devices (e.g., transistors, solid-state diode

Combined with electrical contact or lead

Beam leads

C257S673000, C257S737000, C361S813000

Reexamination Certificate

active

06310395

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electronic component manufactured using an anodic junction and a method of manufacturing the electronic component and, more particularly, to an electrical-contact between a wire and an electrode with an insulating layer surrounding each electrode on a semiconductor chip surface, an electrically conductive surface of each wire being anodically bonded when the wire is simultaneously pressure-joined and connected to an electrode on the semiconductor chip surface.
2. Description of the Related Art
FIG. 39
is a perspective view showing electrodes
2
attached to a surface of a semiconductor chip
1
, according to a conventional ultrasonic thermocompression wire bonding method, connected through gold wires
5
to inner leads
4
extending from lead frames, not shown.
FIG. 40
is a diagrammatic illustration of one end of the gold wire connected to the electrode
2
on the semiconductor chip
1
by ultrasonic thermocompression bonding.
In
FIG. 40
, the semiconductor chip
1
is fixedly secured through a die bonding material
6
to a die pad
41
. The die bonding material
6
and the die pad
41
can withstand the pressure from a capillary
7
when a ball
51
at the tip of the gold wire
5
is connected to the electrode
2
by ultrasonic thermocompression bonding and, further, to support the semiconductor chip
1
. In the ultrasonic thermocompression wire bonding method, the tip of the gold wire
5
passing through the capillary
7
is turned into the ball
51
by means of a high-voltage discharge. Subsequently, the ball
51
is pressed against the electrode
2
on the semiconductor chip
1
and subjected to ultrasonic vibration and heat, whereby it is ultrasonically thermocompression-bonded to the electrode
2
, as indicated at
52
in the same illustration. Further, the capillary
7
is moved to the position of the tip of the inner lead
4
before being lowered to couple the tip of the inner lead
4
to the gold wire
5
.
FIGS. 41A
,
41
B, and
42
are illustrations of a structure of a lead frame with the electrodes
2
coupled through the gold wires
5
to the tips of the inner leads
4
in accordance with a conventional ultrasonic thermocompression wire bonding method. In
FIG. 41A
, a frame
3
is integral with eight die pads
41
, not shown, and thirty-six inner leads
4
, not shown.
FIG. 41B
is an enlarged view showing a portion indicated by X in FIG.
41
A. In
FIG. 41B
, the frame
3
has thirty-six inner leads
4
at its inside portion, a die pad
41
supported by suspending leads
42
at the central portion of the frame, and external leads
44
at its circumferential portion.
FIG. 42
is an illustration of the detailed structure of the thirty-six inner leads
4
, die pad
41
, and suspending leads
42
. In the same illustration, a rectangle indicated by a broken line is representative of a position that is encapsulated with a molding resin.
FIG. 43
is a cross-sectional view showing a semiconductor device completed such that the electrode
2
is connected through the gold wire
5
to the inner lead
4
by ultrasonic thermocompression wire bonding before the frame
3
is encapsulated with a molding resin
8
. In the same illustration, reference numeral
53
designates a contact portion between the inner lead
4
and the gold wire
5
due to the ultrasonic thermocompression bonding.
FIG. 44
is an enlarged view showing a pressure-bonded portion between an electrode, not shown, and the inner lead
4
on the chip
1
, and
FIG. 45
is an illustration of the deformation of the ball
51
when the ball
51
is ultrasonically thermocompression-bonded onto the electrode
2
on a surface of the semiconductor chip
1
. When the electrode
2
is an aluminum electrode, the gold wire
5
and the deformed ball portion
52
both consist of the same gold wire material at the time of completion of the ultrasonic thermocompression bonding, while an alloy of gold and aluminum is formed as a pressure-bonded layer
54
with the aluminum electrode. Reference numeral
2
i
depicts an electrically insulating passivation film (which will be referred to hereinafter as an electrically insulating film) attached to the semiconductor chip
1
at a position other than the electrode
2
.
FIG. 46
illustrates a deformed ball portion
52
of the gold wire
5
pressed against the electrode
2
by means of the capillary
7
in the completed connection.
FIG. 47
shows the other end of the gold wire
5
stitch-bonded to the inner lead
4
by the capillary
7
and its deformed portion
53
pressed against the tip of the inner lead
4
. In
FIG. 47
, although the material of the deformed portion
53
stitch-bonded to the inner lead
4
depends upon the lead frame material, when an iron frame is used, it is silver plated, and hence an alloy layer made of gold and silver is produced on the stitch side. For this reason, the alloy layer
54
of gold is present, as shown in
FIG. 45
, but has been omitted in FIG.
47
.
FIGS. 48A
to
48
E are illustrations for describing processes taken when the inner lead
4
is connected through the gold wire
5
to an electrode on the semiconductor chip
1
according to the conventional ultrasonic thermocompression wire bonding technique. In
FIG. 48A
, heat is transferred from a heating block
9
through the die pad
41
to the chip
1
by heat conduction. The tip of the gold wire
5
leading from the tip of the capillary
7
is formed into a ball by a high voltage power supply torch
10
.
FIG. 48B
shows the capillary
7
lowered toward the electrode
2
(omitted from the illustration) so that the formed ball
51
is pressure-bonded to the electrode under ultrasonic vibration and pressure.
FIG. 48C
illustrates the capillary
7
through which the gold wire
5
passes moved toward the inner lead
4
in order for the other end of the gold wire
5
to be connected to the inner lead
4
after ultrasonic thermocompression bonding of the ball
51
is completed, as shown in FIG.
45
.
FIG. 48D
is illustrative of the other end of the gold wire
5
stitch-bonded to the inner lead
4
, and
FIG. 48E
is illustrative of the other end of the gold wire
5
pressure-attached to the inner lead
4
by the stitch bonding in the state as shown in
FIG. 47
, before the gold wire
5
is held and lifted by a clamp
11
of the capillary
7
, to be cut off at the stitch bonded portion.
FIG. 49
is a plan view of a semiconductor chip
1
produced such that the electrode
2
and the inner lead
4
are coupled through the gold wire
5
to each other by means of ultrasonic thermocompression bonding.
FIG. 50
illustrates nineteen electrodes
2
on the semiconductor chip
1
wherein reference numeral
2
i
designates an electrically insulating film attached to a portion other than the electrodes
2
on the semiconductor chip
1
. The electrode
2
has dimensions C×E and the electrically insulating film
2
i
has dimensions B×D, larger than the dimensions of the electrode
2
, and hence the boundary between the electrode
2
and the electrically insulating film
2
i
appears so that the electrode
2
is exposed as shown in FIG.
51
. The cross-sectional structure of the semiconductor chip
1
is such that the electrically insulating film
2
i
overlaps the circumferential portion of the electrode
2
, as shown in FIG.
45
. As illustrated in
FIG. 51
, in order to increase the electrical and mechanical degree of coupling of the gold wire
5
, the area of the electrode
2
should be larger than the circumferential area of the deformed ball
52
when the ball
51
is ultrasonically thermocompression-bonded.
Depending upon the accuracy of the wire bonding apparatus, the dimension A between the electrodes
2
as shown in
FIG. 51
is determined taking the circumferential dimension of the deformed ball
52
and other factors into consideration. In general, as long as the ultrasonic thermocompression bonding is made, the width of the electrode
2
to be wire-bonded should be larger than the width of

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