Active solid-state devices (e.g. – transistors – solid-state diode – Non-single crystal – or recrystallized – semiconductor... – Amorphous semiconductor material
Reexamination Certificate
2002-03-20
2004-06-15
Ghyka, Alexander (Department: 2812)
Active solid-state devices (e.g., transistors, solid-state diode
Non-single crystal, or recrystallized, semiconductor...
Amorphous semiconductor material
C257S068000, C438S151000, C438S455000
Reexamination Certificate
active
06750476
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a manufacturing method for a substrate device having a bonding interface on a substrate of an SOI (Silicon On Insulator) structure, as well as such a substrate device. The invention also relates to a manufacturing method for an electrooptical apparatus including a liquid-crystal device having a substrate device, as well as such an electrooptical device. The invention further relates to an electronic appliance having such an electrooptical device.
2. Description of Related Art
It is a general practice to manufacture an SOI-structured substrate device, which is one example of a substrate device having a bonding interface on a substrate thereof. An insulating film is formed on the surface of a main substrate, on one hand. On the other hand, an insulating film is formed on the surface of a semiconductor substrate that is separately prepared. Then, both substrates, in a state that they are closely contacted at the insulating films, are thermally processed to bond the insulating films together. Thereafter, the semiconductor substrate is separated so that a predetermined film thickness of a single-crystal semiconductor layer that is close to the bonding interface is left on the main substrate. This provides an SOI structure having these insulating films on the main substrate on which a single-crystal semiconductor layer is further formed. Thereafter, the thus formed single-crystal semiconductor layer is used to fabricate, thereon, semiconductor elements of thin film transistors (hereinafter “TFTs”), thin-film diodes (hereinafter “TFDs”) and the like, thereby completing a substrate device.
With such a bonding technique, it is possible to form, on the substrate, high-performance semiconductor elements including a single-crystal semiconductor layer provided on a transparent substrate, e.g., a quartz glass substrate or a glass substrate, and to also form this structure on a semiconductor substrate.
SUMMARY OF THE INVENTION
However, in accordance with the above method, there is a tendency that the structure becomes complicated and that the thickness of the structure increases. For example, where an electrooptical device, such as a liquid-crystal device, is manufactured by using this type of substrate device, there is a need to form the layers of a light shielding film and interconnections at a position beneath the single-crystal semiconductor layer as well as above it. Particularly, there arises a necessity to electrically connect the light shielding film or interconnection and the other interconnection or element formed in the layers over the single-crystal semiconductor layer. In such a case, it is required to open a contact hole penetrating the interface between the insulating films. According to the research by the present inventor, where a contact hole penetrating such a bonding interface is opened simply by etching, an etch solution intrudes to the bonding interface. This may cause cracks or strip at a point in the contact hole passing the bonding interface, irregularly broadening in the bonding-interface gap in a direction along the substrate surface, poor electrical connection or insulation due to the contact hole, or poor electrical connection and insulation in the other interconnections and elements positioned close to the contact hole, for example.
As described above, the SOI or bonding technique per se that is generally used in the manufacturing method for a semiconductor device is advantageous. However, where this method is applied to a comparatively complicated overlying structure and particularly requiring a contact hole penetrating a bonding interface, as in the substrate device for an electrooptical device, such as a liquid-crystal device, defects, such as cracks and strip, may occur at the point in the contact hole passing the bonding interface. Thus, a serious malfunction in the device may be eventually incurred, which reduces the manufacturing yield.
The present invention addresses the foregoing problem, and provides a manufacturing method for a substrate device and such a substrate device capable, where manufacturing a substrate device requiring an open contact hole penetrating a bonding interface, of causing less defects at the point in the contact hole passing the bonding interface to finally enhance device reliability and thus manufacturing yield. The invention also provides a manufacturing method for an electrooptical device including the manufacturing method for a substrate device, such an electrooptical device, and an electronic appliance having such an electrooptical device.
A method for manufacturing a substrate device of the present invention that addresses the foregoing problem. The substrate device includes, on a substrate, a first conductive film, a first insulating film formed overlying the first conductive film, a second insulating film bonded on the first insulating film, a second conductive film overlying the second insulating film, and a contact hole opened in the first and second insulating films to connect the first conductive film and the second conductive film, and penetrate a bonding interface between the first insulating film and the second insulating film. The method includes a bonding step of bonding the first insulating film and the second insulating film together; an etching step of opening the contact hole penetrating the bonding interface by etching after the bonding step; a connecting step of electrically connecting between the first conductive film and the second conductive film through the contact hole. The etching process is made by dry etching that is started at least before an etchant reaches the bonding interface.
According to the method for manufacturing a substrate device of the invention, at first the first insulating film and the second insulating film are bonded together, for example, by a thermal process or the like in the bonding process. Thereafter, in the etching process, a contact hole is opened by etching that penetrates the bonding interface. On this occasion, dry etching is conducted at least before an etchant reaches the bonding interface. Thereafter, in the connection process, the first conductive film and the second conductive film are electrically connected through the contact hole. Consequently, electrical connection is provided, through the contact hole extending perpendicular to a substrate surface, between the interconnection, electrode, element or the like formed by the first conductive film and the interconnection, electrode, element or the like formed by the second conductive film, that are formed in the films sandwiching the bonding interface. Particularly, because the etching process to open a contact hole is made by dry etching that is high in directivity by the use of an etching gas at least before the etchant reaches the bonding interface, there is no possibility that the etch solution intrude to the bonding interface as encountered in wet etching. As a result, there is a reduced or almost no possibility that cracks or strip occur in a point of the contact hole passing the bonding interface or irregularly broadening in the gap at the bonding interface in a direction along the substrate surface. Accordingly, reliable electrical connection is available by the contact hole. Furthermore, reliable electrical connection or insulation is available in the other interconnection, element or the like that is positioned close to that contact hole.
As a result of the above, where the bonding technique is applied to the application requiring such a contact hole as having a comparatively complicated overlying structure and penetrating particularly a bonding interface, as in the substrate device for an electrooptical device, such as a liquid-crystal device, defects can be reduced at the point of the contact hole passing the bonding interface. This ultimately conspicuously enhances device reliability and manufacturing yield of the substrate device.
In one form of a method for manufacturing a substrate device of the invention, the substrat
Ghyka Alexander
Oliff & Berridg,e PLC
Seiko Epson Corporation
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