Semiconductor device manufacturing: process – Making field effect device having pair of active regions... – On insulating substrate or layer
Reexamination Certificate
1999-08-18
2002-04-16
Smith, Matthew (Department: 2825)
Semiconductor device manufacturing: process
Making field effect device having pair of active regions...
On insulating substrate or layer
C438S150000, C438S155000, C349S042000, C349S043000
Reexamination Certificate
active
06372558
ABSTRACT:
RELATED APPLICATION DATA
The present application claims priority to Japanese Application No. P10-231855 filed Aug. 18, 1998 and Japanese Application No. P10-255275 filed Sep. 9, 1998 which applications are incorporated herein by reference to the extent permitted by law.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electrooptic device a driving substrate for an electrooptic device, and a method of manufacturing the electrooptic device and the substrate. Particularly, the present invention relates to a structure and method suitable for a liquid crystal display device or the like which comprises an active region comprising top gate type thin film insulating gate electric field effect transistors (referred to as “top gate type MOSTET” hereinafter, which includes a stagger type and a coplanar type) formed by using a single crystal silicon layer hetero-epitaxially grown on an insulation substrate, and a passive region.
2. Description of the Related Art
Known examples of active matrix type liquid crystal display devices include a device comprising a display region comprising amorphous silicon TFTs, and external driving circuit IC, a device comprising a display region comprising polycrystalline silicon TFTs, and driving circuits, which are integrated (Japanese Unexamined Patent Publication No. 6-242433), a-device comprising a display region comprising TFTs made of polycrystalline silicon formed by excimer laser annealing, and driving circuits, which are integrated (Japanese Unexamined Patent Publication No. 7-131030), and the like.
Although the above-described conventional amorphous silicon TFT has good productivity, p-channel MOSTFT (referred to as “pMOSTFT” hereinafter) cannot be formed because electron mobility is as low as about 0.5 to 1.0 cm
2
/v·sec. Therefore, the peripheral driving region using pMOSTFT and the display region cannot be formed on the same glass substrate, and thus driver IC is externally provided and is mounted by a TAB system or the like, causing difficulties in decreasing cost. This also causes a limit to an increase in definition. In addition, a sufficient on-current cannot be obtained because electron mobility is as low as about 0.5 to 1.0 cm
2
/v·sec, and the use of the amorphous silicon TFT for the display region inevitably increases the transistor size, causing disadvantages for increasing the aperture ratio of pixels.
The above-described conventional polycrystalline silicon TFT has an electron mobility of 70 to 100 cm
2
/v·sec, and can comply with the need to increase definition.
Therefore, LCD (liquid crystal display) comprising polycrystalline silicon TFTs integrated with driving circuits has recently attracted attention. However, in large LCD of 15 inches or more, the driving ability is insufficient because the electron mobility of polycrystalline silicon is 70 to 100 cm
2
/v·sec, thereby causing the need for an external driving circuit.
In TFT comprising polycrystalline silicon formed by a solid phase growth method, there is the need for forming gate SiO
2
by annealing at 600° C. or more for ten-odd hours, and thermal oxidation at about 1000° C., and thus a semiconductor producing apparatus must be used. Therefore, the wafer size is limited to 8 to 12 inches Ø, and expensive quarts glass having high heat resistance must be used, causing difficulties in decreasing cost. Application of this TFT is thus limited to EVF and data/AV projectors.
The above-described conventional polycrystalline silicon TFT formed by excimer laser annealing has problems of stability of excimer laser output, productivity, an increase in equipment cost due a size increase, deterioration in yield and quality, etc.
Particularly, in a 1-m square large glass substrate, the above problems become significant, and it is more difficult to improve performance and quality, and decrease the cost.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to permit uniform deposition of a single crystal silicon thin film having high electron/hole mobility at a relatively low temperature to manufacture an active matrix substrate comprising a built-in high-performance driver, and an electrooptic device such as a thin film semiconductor device for display comprising the active matrix substrate, thereby permitting a structure in which a display region comprising n-channel MOSTFTs (referred tb as “nMOSTFTs” hereinafter) or pMOSTFTs having a LDD structure (lightly doped drain structure) having high switching properties and a low leak current, or complementary thin film insulation gate electric field effect transistors (referred to as “cMOSTFTs” hereinafter) having a high driving ability is integrated with peripheral driving circuits comprising cMOSTFT, nMOSTFT, pMOSTFT, or a mixture thereof. This can realize a display panel having high image quality, high definition, a narrow frame, high efficiency and a large screen, and permits the use of a large glass substrate having a relatively low strain point, and a decrease in cost due to high productivity and no need for an expensive manufacturing apparatus, as well as permitting a high-speed operation and a large screen due to the resistance decrease caused by the ease of threshold control
The present invention provides an electrooptic device and a driving substrate therefor comprising a display region comprising pixel electrodes (for example, a plurality of pixel electrodes arranged in a matrix), and a peripheral driving circuit region arranged in the periphery of the display region, which are provided on a first substrate (i.e., a driving substrate), and a predetermined optical material such as a liquid crystal held between the first substrate and a second substrate (i.e., a counter substrate), wherein a material layer having good lattice matching with a single crystal semiconductor such as single crystal silicon or the like is formed on one side of the first substrate, a single crystal semiconductor layer such as a single crystal silicon layer is formed on the first substrate including the material layer so as to constitute at least active elements of the active and passive elements. In the present invention, of course, the single crystal semiconductor layer includes a single crystal silicon layer and a single crystal compound semiconductor layer. The active elements include a thin film transistor, and other elements such as a diode and the like, and the passive elements includes a resistor and the like. Thin film transistors as a typical example include a field effect transistor (FET) (including a MOS type and junction type, both of which can be used), and a bipolar transistor. However, the present invention can be applied to both types of transistors. The passive elements include a resistor, an inductor, capacitor, and the like. An example of the passive elements is a capacitor formed by sandwiching a highly dielectric film of silicon nitride (referred to as “SiN” hereinafter) or the like between single crystal silicon layers (electrodes).
The present invention also provides a method of manufacturing the electrooptic device and the driving substrate thereof, comprising the steps of forming a material layer having good lattice matching with a single crystal semiconductor such as single crystal silicon or the like on one side of the first substrate, hetero-epitaxially growing a single crystal silicon layer on the first substrate including the material layer by a catalytic CVD method or high-density plasma CVD method using the material as a seed, and forming at least the active elements of the active and the passive elements by predetermined processing of the single crystal semiconductor layer. For example, after the single crystal silicon layer is deposited, the single crystal silicon layer is subjected to predetermined processing to form channel regions, source regions and drain regions, and gate regions comprising a gate insulation film and a gate electrode are formed on the channel regions, and source and drain electrodes are further formed to form top gate type first thin film t
Sato Yuichi
Yagi Hajime
Yamanaka Hideo
Yamoto Hisayoshi
Malsawma Lex H.
Smith Matthew
Sonnenschein Nath & Rosenthal
Sony Corporation
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