Semiconductor device manufacturing: process – Bonding of plural semiconductor substrates – Thinning of semiconductor substrate
Reexamination Certificate
2000-03-22
2002-08-06
Nguyen, Ha Tran (Department: 2812)
Semiconductor device manufacturing: process
Bonding of plural semiconductor substrates
Thinning of semiconductor substrate
C438S406000, C438S455000, C438S460000, C438S465000, C438S612000
Reexamination Certificate
active
06429096
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device and a manufacturing method therefor which are applied to the fabrication of electronic equipment. More particularly, it relates to a semiconductor device wafer for incarnating the ultrathin and light construction of electronic equipment, as well as a semiconductor device having a structure in which such wafers are mounted in three dimensions (namely, in multilevel fashion), and a method of manufacturing the semiconductor device wafer as well as the semiconductor device.
2. Description of the Related Art
In order to promote reduction in the size of electronic equipment still further, it becomes an important point how the mounting density of semiconductor device components is heightened. Regarding also semiconductor ICs (integrated circuits), high-density mounting techniques, such as flip-chip mounting, in which an LSI (large-scale integrated circuit) chip is directly mounted on a printed-wiring circuit board alternatively to conventional package mounting, have been vigorously developed in the business world.
One of connecting methods based on a flip chip is a method wherein solder ball bumps are formed and mounted on the Al (aluminum) electrode pads of a semiconductor IC. A method of forming the solder ball bumps on the predetermined electrodes, employs electroplating. This method has the problem of being basically difficult to form the solder ball bumps of uniform heights within an IC chip because the thickness of a solder film to be formed is affected by slight dispersions in the surface state and electric resistance of a subbing material layer.
Dispersion in the heights of such solder ball bumps can be suppressed by a pattern forming method which employs the formation of the solder film by vacuum evaporation and the lift-off of a photoresist film. An example of a process for forming the solder ball bumps in accordance with this method, is illustrated in
FIGS. 1A-1E
of the accompanying drawings.
FIGS. 1A-1E
are sectional views showing a method of forming solder ball bumps on Al electrode pads.
First, as shown in
FIG. 1A
, a film of Al—Cu (copper) alloy or the like is deposited on a semiconductor substrate
1
of silicon or the like by sputtering, and it is etched, whereby each Al electrode pad
2
is formed on the semiconductor substrate
1
. Subsequently, the whole surface of the semiconductor substrate
1
including the Al electrode pads
2
is covered with a surface protective film
3
which is made of silicon nitride, polyimide or the like, whereupon the surface protective film
3
is formed by etching with each opening
3
a
which overlies the electrode pad
2
. Subsequently, each BLM (Ball Limiting Metal) film
4
is formed in the opening
3
a
and on the surface protective film
3
by sputtering. Thus, each joint portion of a flip-chip IC is formed. Incidentally, the BLM film
4
is a multilayer metal film which is made of at least two of Cr (chromium), Cu, Au (gold), etc.
Thereafter, as shown in
FIG. 1B
, a resist pattern
6
which has each opening
5
overlying the BLM film
4
is provided on the surface protective film
3
. Subsequently, as shown in
FIG. 1C
, an evaporated solder film
13
is formed on the whole surface of the resulting structure including the interior of each opening
5
.
Thereafter, as shown in
FIG. 1D
, the unnecessary part of the evaporated solder film
13
is removed together with the resist pattern
6
by lifting off this resist pattern
6
, whereby the desired pattern of the evaporated solder film is formed on the BLM films
4
. Subsequently, as shown in
FIG. 1E
, the solder of the evaporated solder film is molten by a heat treatment, whereby each refractory solder ball bump
14
is finally formed on the corresponding BLM film
4
.
The device chip formed with the bumps by employing the process proposed by the inventors as explained above is mounted on a printed-wiring circuit board by flip-chip mounting. Then, a mother board can be made smaller than in case of mounting a conventional device packaged with a molding resin. Therefore, the inventors have contributed to the incarnation of the smaller and lighter constructions of various electronic equipment.
Nevertheless, the mounting space of a semiconductor device should be reduced to the utmost for each of portable electronic equipment including an IC card, a portable telephone, a PDA (Personal Digital Assistant), etc. Accordingly, it is earnestly desired to establish a stacked (or multilayer) three-dimensional (or multilevel) high-density mounting technique which can make the semiconductor device still thinner in the height direction thereof, in addition to two-dimensional (or areal) space saving which has heretofore been mainly aimed at.
SUMMARY OF THE INVENTION
The present invention has been made in consideration of the circumstances as stated above, and has for its object to provide a semiconductor device and a manufacturing method therefor according to which the stacked ultrathin three-dimensional (or multilevel) mounting of semiconductor device components can be realized at a high reliability and with a high functionality.
In order to accomplish the object, a method of manufacturing a semiconductor device according to the first aspect of performance of the present invention is characterized by comprising the step of preparing a semiconductor device wafer which is formed with an LSI; the step of working the semiconductor device wafer from a back surface thereof, thereby to diminish a thickness of said semiconductor device wafer to at most 200 [&mgr;m]; the step of forming a penetrant hole in the resulting semiconductor device wafer; and the step of forming a wiring plug in the penetrant hole.
A semiconductor device according to the second aspect of performance of the present invention is characterized by comprising a semiconductor device wafer which is formed with an LSI in its front surface, and which has been worked from its back surface, thereby to diminish its thickness to at most 200 [&mgr;m]; a penetrant hole which is formed in the semiconductor device wafer; and a wiring plug which is formed in the penetrant hole.
A method of manufacturing a semiconductor device according to the third aspect of performance of the present invention is characterized by comprising the step of preparing a semiconductor device wafer which is formed with an LSI, and an electrode pad lying at a peripheral edge of the LSI; the step of working the semiconductor device wafer from a back surface thereof, thereby to diminish a thickness of said semiconductor device wafer to at most 200 [&mgr;m]; the step of coating both a front surface and the back surface of the resulting semiconductor device wafer with an insulating material; the step of forming a hole which penetrates through coatings of the insulating material, the electrode pad and said semiconductor device wafer, by laser processing; and the step of forming a wiring plug for joining the front and back surfaces of said semiconductor device wafer, in the hole. Besides, as a working method in the case of working the semiconductor device wafer from the back surface, any can be employed as long as it is a working method adapted to thin the wafer. It is favorable, however, to employ grinding, chemical mechanical polishing, or etching by way of example.
With the method of manufacturing a semiconductor device in the third aspect, each of the surfaces of the wafer before the laser processing is coated with the insulating material in advance, whereby at the step of forming the microscopic penetrant hole in the thin wafer by the laser processing, the tapering angle of the penetrant hole can be restrained from widening at that opening end of the surface to-be-processed which a laser beam enters. As a result, the penetrant hole having a more perpendicular (or less tapering) sectional shape can be stably formed, and the penetrant hole joining the front surface and back surface of the wafer can be formed at a high precision
Nguyen Ha Tran
Sonnenschein Nath & Rosenthal
Sony Corporation
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