Semiconductor device manufacturing: process – Making device array and selectively interconnecting – Using structure alterable to nonconductive state
Reexamination Certificate
2000-05-11
2003-07-01
Niebling, John F. (Department: 2812)
Semiconductor device manufacturing: process
Making device array and selectively interconnecting
Using structure alterable to nonconductive state
C438S131000, C438S600000, C438S601000, C438S401000, C438S462000, C257S529000, C257S530000
Reexamination Certificate
active
06586282
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor device having a pattern for position registration for cutting a fuse element formed on a semiconductor chip surface by irradiating a laser beam with high accuracy.
2. Description of the Related Art
A laser trimming method for adjusting analog characteristics is known in a device of an analog semiconductor integrated circuit. For example, the laser trimming method is described in Japanese Laid-Open (Kokai) Patent No. 5-13670. In this method, after integrated circuits are two-dimensionally patterned in a semiconductor wafer, electric characteristics of each integrated circuit are measured in a wafer state. Next, a fuse element arranged in one portion of wiring is selected to adjust the analog characteristics and is cut by irradiating a laser beam. The analog characteristics of the integrated circuit can be conformed to desirable characteristics by selectively cutting the fuse element by such a laser trimming method. A pattern for position registration is arranged on a semiconductor wafer surface to irradiate the laser beam to a predetermined fuse element.
FIG. 3A
is a plan view of a conventional laser trimming position registration pattern.
FIG. 3B
is a cross-sectional view of the conventional laser trimming position registration pattern.
FIG. 3C
is a view showing a change in light reflecting amount when this pattern for laser trimming position registration is scanned along the direction of a line C-C′ by the irradiation of the light beam. As shown in
FIG. 3A
, the conventional laser trimming position registration pattern is constructed by a so-called theta mark
301
, an X-direction trimming mark
302
and a Y-direction trimming mark
303
. The theta mark
301
is arranged on a scribe line
203
to perform a relative rough position registration operation with respect to a rotating direction of the semiconductor wafer. The X-direction trimming mark
302
and the Y-direction trimming mark
303
are arranged to perform an accurate position registration operation with respect to each of semiconductor integrated circuits
201
repeatedly arranged. The theta mark
301
is desirably formed in a characteristic shape different from that of a pad area
202
, etc. within the semiconductor integrated circuits
201
so as to automatically recognize an image.
In an example of
FIG. 3A
, the shape of the theta mark
301
is of a key type, but may be set to another shape if this shape is a singular shape and is easily recognized.
As shown in
FIG. 3B
, in the conventional position registration pattern, a square aluminum film
105
is arranged on a first insulating film
102
constructed by a silicon oxide film arranged on a silicon substrate
101
. When the light beam is scanned along the direction of the line C-C′ of
FIG. 3A
, a light reflecting pattern is obtained as shown in
FIG. 3C
since reflectivity of the aluminum film
105
is high. A position relation between the position registration pattern and the fuse element constructed by a polycrystal silicon film of the integrated circuit is determined at a designing time. Accordingly, the coordinates of a desirable fuse element are calculated by detecting the position registration pattern by the irradiation of the light beam, and the fuse element can be selectively trimmed by irradiating the laser beam to this coordinate place.
However, in the conventional laser trimming, no accurate position registration operation can be performed since the fuse element and the position registration pattern are formed by different thin films. Namely, when the pattern for position registration is detected by a pattern of aluminum and the polycrystal silicon film as the fuse element is laser-trimmed, the position of a laser irradiating area
32
is shifted from the fuse element
31
as shown in FIG.
4
. Since an energy distribution of the laser irradiating area
32
is set to a Gaussian distribution, energy intensity in a laser irradiating end portion is low. Accordingly, when there is a large shift in alignment between patterning of the polycrystal silicon film and patterning of the aluminum film in a wafer process, a problem exists in that no fuse element can be stably cut. Reference numerals
33
and
34
respectively designate a burning portion of a foundation and a portion left in the fuse cut.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a method of manufacturing a semiconductor device capable of precisely performing position registration and trimming operations with respect to a fuse element of a semiconductor chip without increasing the number of normal semiconductor integrated circuit manufacturing processes. Another object of the present invention is to make a fuse element area compact and reduce cost by improving a position registration accuracy of trimming.
To solve the above-mentioned problems, the present invention uses the following means.
(1) A semiconductor device is constructed by semiconductor integrated circuits repeatedly arranged two-dimensionally in a matrix shape on the surface of a semiconductor wafer through scribe lines, a fuse element for laser trimming arranged in the semiconductor integrated circuits, and a pattern for laser trimming position registration arranged on the surface of the semiconductor wafer. The pattern for laser trimming position registration is constructed by a high light reflectivity area and a low light reflectivity area. The high light reflectivity area is formed by a high light reflectivity film formed on a flat foundation. The low light reflectivity area is formed by a high light reflectivity film constructed by the same thin film as the fuse element for laser trimming and formed on the pattern of a grid, stripe or dot shape for causing irregular reflection of light.
(2) In the semiconductor device described in the item (1), the pattern for laser trimming position registration is constructed by the high light reflectivity area and the low light reflectivity area surrounded by the high light reflectivity area.
(3) In the semiconductor device describe in the item (1), the pattern for laser trimming position registration is constructed by the low light reflectivity area and the high light reflectivity area surrounded by the low light reflectivity area.
(4) In the semiconductor device described in the item (1), the fuse element for laser trimming is constructed by a polycrystal silicon thin film.
(5) In the semiconductor device described in the item (1), the high light reflectivity film is constructed by aluminum.
The present invention provides a manufacturing method capable of manufacturing the semiconductor device described in the above items (1) to (5) without increasing the number of normal manufacturing processes of the semiconductor integrated circuits.
REFERENCES:
patent: 5538924 (1996-07-01), Chen
patent: 5567643 (1996-10-01), Lee et al.
patent: 5869383 (1999-02-01), Chien et al.
patent: 6180503 (2001-01-01), Tzeng et al.
patent: 6320242 (2001-11-01), Takasu et al.
patent: 6372554 (2002-04-01), Kawakita et al.
Adams & Wilks
Kennedy Jennifer M.
Seiko Instruments Inc.
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