Active matrix array devices are constituted by devices having a function such as those of display/light emitting devices, sensors, memories, or actuators, and are arranged in a matrix array shape, and are used in various fields and applications.
Active matrix array devices are structured based on matrix elements in each of which a device such as a display or a sensor and a circuit that controls the device are included as a unit, and a conductor (interconnect) group in which conductors extend in a row direction and a column direction of the matrix so as to transmit a control signal or the like to each of the matrix elements. The row interconnects and the column interconnects intersect inside the respective matrix elements or adjacent regions thereof. The control circuit that constitutes a matrix element differs in complexity ranging from a circuit constituted by one transistor to a circuit that is complex, depending on the application. Also, in the case where the device of the matrix element is a sensor, an interconnect for transmitting an output signal of the sensor is added to the basic structure.
The field in which the application of active matrix array devices is most widespread is the field of display. Liquid crystal display is the most widely used in the field of display. In the case of liquid crystal display, a pixel that is constituted by a liquid crystal layer interposed between electrodes and a thin film transistor (TFT) for applying a voltage thereto corresponds to the matrix element, and the row interconnect is referred to as a gate line and the column interconnect is referred to as a data line or the like. Devices in which sensors are arranged in an active matrix array are expected as new future application examples.
In addition, in recent years, semiconductor technology in which an organic material is used has advanced, and it can be said that an organic TFT that uses an organic semiconductor can be applied as the control circuit of a matrix element. The organic TFT can be formed on a soft and bendable film at a low cost, and therefore the creation of a new application field, namely a flexible active matrix array device, is expected.
In the case of a conventional field of display that is already at a mature stage, a high temperature is required to form a TFT, and an active matrix array device needs to be formed on a glass substrate having high heat resistance, and therefore increasing the size of the device is difficult due to limitations in reducing the weight of the device, and in terms of manufacturing process technology, or manufacturing costs. However, as a result of reducing the weight of the substrate by adopting the organic TFT technology this problem can be avoided, and a large-size display aimed at being installed outdoors, in a large commercial complex, a hall, or the like can be manufactured using an active matrix array method.
Accordingly, the creation of a new application field of the active matrix array device can be expected in this way, but there is a common issue irrespective of the application field. That is, there is little similarity and compatibility between processes and materials for forming the control circuits of the matrix elements and those for forming other portions. Therefore, the control circuits and the other portions are mutually restricting factors in terms of selection of materials and process conditions, and as a result, the product specification of the device is restricted, and the manufacturing cost increases. Also, the control circuits, although being arranged in the entire matrix array often have a small area ratio relative to the entire device. This incurs wasteful material consumption and hidden increases in the manufacturing cost that cannot be directly seen.
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