Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – To form ohmic contact to semiconductive material
Reexamination Certificate
2000-02-08
2001-06-19
Nelms, David (Department: 2818)
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
To form ohmic contact to semiconductive material
C438S459000
Reexamination Certificate
active
06248657
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device comprising an electronic circuit and a method for manufacturing the semiconductor device, and more particularly to electrical protection for the electronic circuit.
2. Description of the Background Art
In a semiconductor device according to the prior art, a surge caused by static electricity is sometimes propagated with a high voltage or a great current to an electronic circuit provided therein.
Accordingly, there has been a problem that the electronic circuit provided in the semiconductor device is broken by the surge. In a semiconductor device having a SOI (Silicon On Insulator) structure, particularly, an electronic circuit provided therein is easily broken by the surge.
FIG. 33
shows an example of a section of the semiconductor device having the SOI structure. In
FIG. 33
, the reference numeral
13
denotes a p-type semiconductor region in a SOI substrate (hereinafter referred to as a semiconductor substrate), the reference numeral
111
denotes a SOI layer (semiconductor layer), the reference numeral
14
denotes a buried oxide film, and the reference numeral
112
denotes a MOS transistor provided on the SOI layer
111
and forming an electronic circuit, a gate G, a source S and a drain D being shown. The buried oxide film
14
has a very poor thermal conductivity. For example, SiO
2
has a thermal conductivity of about one hundredth as compared with single crystal Si. Consequently, when the surge is propagated between the source S and the drain D, the temperatures of the source S and the drain D are raised so that the source S and the drain D are easily broken.
SUMMARY OF THE INVENTION
A first aspect of the present invention is directed to a semiconductor device comprising a semiconductor substrate, an electronic circuit provided on the semiconductor substrate, a terminal conducted to the electronic circuit, and a metal connecting member bonded, in common, to both the terminal and a region of a surface of the semiconductor substrate which is exposed adjacently to the terminal, a diode having the surface of the semiconductor substrate as one of electrodes being formed between the connecting member and the semiconductor substrate.
A second aspect of the present invention is directed to the semiconductor device wherein the metal forms a Schottky junction together with the region.
A third aspect of the present invention is directed to the semiconductor device wherein the region has a conductivity type which is reverse to a conductivity type of the semiconductor substrate.
A fourth aspect of the present invention is directed to the semiconductor device, further comprising an insulating film formed between the semiconductor substrate and the terminal, enclosing the electronic circuit, and exposed adjacently to the terminal together with the region, and a conductive member formed over the insulating film and the region.
A fifth aspect of the present invention is directed to the semiconductor device wherein the region is provided in a center of the terminal.
A sixth aspect of the present invention is directed to a semiconductor device comprising a semiconductor chip including a semiconductor substrate, an insulating film formed on the semiconductor substrate, and a semiconductor layer formed on the insulating film and having an electronic circuit formed thereon, a protective substrate for electrically protecting the semiconductor layer, an external terminal, a first connecting member for electrically connecting the semiconductor chip and the protective substrate, and a second connecting member for electrically connecting the protective substrate and the external terminal.
A seventh aspect of the present invention is directed to a method for manufacturing a semiconductor device, comprising the steps of (a) preparing a semiconductor substrate, an insulating film formed on the semiconductor substrate, a semiconductor layer formed on the insulating film and having an electronic circuit formed thereon, a terminal conducted to the electronic circuit, and an external terminal, (b) forming an opening on the insulating film to expose the semiconductor substrate, (c) connecting one of ends of a metal connecting member to the external terminal, and (d) bonding the other end of the connecting member to the exposed semiconductor substrate and the terminal.
An eighth aspect of the present invention is directed to the method for manufacturing a semiconductor device, further comprising, between the steps (b) and (c), a step of (e) making a conductivity type of a surface of the exposed semiconductor substrate different from that of the semiconductor substrate.
A ninth aspect of the present invention is directed to the method for manufacturing a semiconductor device, further comprising, between the steps (e) and (c), a step of (f) forming a conductive member from the surface of the exposed semiconductor substrate to a sidewall of the opening.
A tenth aspect of the present invention is directed to the semiconductor device wherein the electronic circuit is provided on a SOI structure.
An eleventh aspect of the present invention is directed to the method for manufacturing a semiconductor device wherein the electronic circuit is provided on a SOI structure.
A twelfth aspect of the present invention is directed to the semiconductor device wherein the electronic circuit is provided on a SOI structure.
According to the first aspect of the present invention, in a case where a surge is propagated from the connecting member to a bonding pad, it is sent to the semiconductor substrate through a diode. Accordingly, the electronic circuit can be protected from the surge.
According to the second aspect of the present invention, a Schottky type diode is formed between the connecting member and the surface of the semiconductor substrate. Therefore, the effects according to the first aspect of the present invention can easily be obtained.
According to the third aspect of the present invention, a PN junction type diode is formed on the surface of the semiconductor substrate. Therefore, a resistance is smaller during breakdown as compared with the Schottky type diode. Consequently, the surge can easily flow to the semiconductor substrate.
According to the fourth aspect of the present invention, when coming in contact with the bonding pad, it becomes harder for the connecting member to come in contact with the region to which the semiconductor substrate is exposed if a thickness of the insulating film is increased. However, if the conductive member is provided, the connecting member can be conducted to the semiconductor substrate.
According to the fifth aspect of the present invention, the region is provided in the center of the terminal. Consequently, even if the connecting member is bonded toward the periphery of the terminal, the connecting member can easily come in contact with the region.
According to the sixth aspect of the present invention, the semiconductor device in which the semiconductor layer having the electronic circuit formed thereon is insulated from the semiconductor substrate by the insulating film has very few paths through which a surge flows out of the semiconductor layer when the surge is propagated from the external terminal to the semiconductor layer. For this reason, the electronic circuit is easily broken by the surge. Therefore, the protective substrate is electrically provided between the external terminal and the semiconductor chip to prevent the surge from being propagated from the external terminal to the semiconductor chip. Consequently, the electronic circuit can be protected from the surge.
According to the seventh aspect of the present invention, generally, the electronic circuit formed on the insulating film discharges the surge with difficulty. However, the connecting member is connected to the external terminal at the step (c). Therefore, the surge flows to the external terminal even if it is generated during the bonding at the step (d). Therefore, the electronic ci
Dang Phuc T.
McDermott & Will & Emery
Mitsubishi Denki & Kabushiki Kaisha
Nelms David
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