Semiconductor device manufacturing: process – Bonding of plural semiconductor substrates
Reexamination Certificate
1999-12-07
2001-03-06
Smith, Matthew (Department: 2825)
Semiconductor device manufacturing: process
Bonding of plural semiconductor substrates
C438S149000, C438S099000
Reexamination Certificate
active
06197663
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention is directed to a process for fabricating a semiconductor device containing a plurality of thin film transistors (TFT's) and an interconnect structure.
2. Art Background
Thin film transistors (TFTs) are known and are of considerable commercial importance. Amorphous silicon-based thin film transistors are used in active matrix liquid crystal displays. One of the advantages of thin film transistors is that they are susceptible to being made at low cost, both in terms of the materials used and the techniques used to make them.
In addition to making the individual TFTs as inexpensively as possible, it is also desired to form the integrated circuit devices that contain TFTs in an inexpensive manner. This involves not only fabricating the TFT's themselves, but the interconnects for the TFTs that are required to operate the integrated circuit. Accordingly, inexpensive strategies for fabricating integrated circuits with TFTs are sought.
SUMMARY OF THE INVENTION
The present invention is directed to a process for fabricating an integrated circuit having thin film transistors. In the process of the present invention, at least a portion of the TFTs are formed on a first flexible substrate. At least the interconnect structure for the integrated circuit is formed on a second flexible substrate. The two flexible substrates are laminated or otherwise joined together to form the desired semiconductor device. If the entire TFT is not formed on the first substrate (e.g. the TFT gate, gate dielectric and semiconductor are formed on the first substrate but the TFT source and drain are not), the portion of the TFT not formed on the first substrate is formed on a different substrate (e.g. the second substrate on which the interconnect structure is formed). In the embodiments wherein a portion of the TFTs are formed on a first substrate and the remaining portion of the TFTs are formed on a second substrate, the TFTs are assembled by laminating the substrates together.
After the TFTs and the associated interconnect structure are formed, the first substrate is laminated to the second substrate to form the integrated circuit. The process of the present invention is advantageous because it is very versatile. Specifically, the process is economical because the more technically challenging and time consuming aspects of the process (e.g. the formation of the TFT source, drain and gate) can be performed on one substrate and the easier aspects of the process (i.e., the formation of the interconnect structure) is performed on the second substrate. Forming the device on two different substrates provides for a greater choice of process conditions and materials. Also, the process of the present invention allows for parallel processing of portions of the device; a first portion on a first substrate and a second portion on a second substrate. Such parallel processing saves time. For example, if a desirable process step is not compatible with the materials and structures already formed on one substrate, then the process step may be performed on the second substrate. Other attendant advantages of the present invention are readily ascertained by one skilled in the art.
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Chandross Edwin Arthur
Dodabalapur Ananth
Katz Howard Edan
Raju Venkataram Reddy
Botos Richard J.
Lucent Technologies - Inc.
Rocchegiani Renzo N.
Smith Matthew
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