Etching a substrate: processes – Forming or treating article containing a liquid crystal...
Patent
1996-01-16
1997-12-02
Powell, William
Etching a substrate: processes
Forming or treating article containing a liquid crystal...
216 2, 216 41, 216 33, 1566571, 15665911, 1566331, H01L 2100, B44C 122
Patent
active
056932375
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a method of producing integrated active-matrix liquid crystal displays (AMLCD) having a monocrystalline silicon disk which is divided, in checkerboard fashion, into image points, wherein each image element comprises a light valve which is constructed from a liquid crystal layer, orientation layers, electrodes and polarization filters and an actuating electronic circuit which is produced in an integrated construction on the top side of the silicon disk and actuates a transparent electrode of the image element. A production method which will be described in detail below as prior art is known from the publication by Salemo, J. P. et al, "Single-Crystal Silicon Transmissive AMLCD" Proceedings of the SID 1992, Digest pp. 63-66.
In the known method, circuits are embodied in a thin, recrystallized polysilicon layer on a silicon wafer. This layer system is applied upside-down on a glass substrate, and the silicon substrate is extensively stripped. The AMLCD cell is completed by a second glass plate and further standard process steps of display technology.
In the described method, the transistors are produced in a recrystallized poly-Si layer. Consequently, the components have poorer electrical properties in comparison to those which are produced in monocrystalline layers. Furthermore, all of the produced components have the same thickness, which leads to limitations in the selection of components and the circuits to be embodied. Moreover, costly conventional cell technology must be used to complete the display cell.
The object of the invention, therefore, is to develop a method of integrating electronic components into AMLCDs with which the actuation electronics and the image elements of the display can be produced cost-effectively.
A liquid crystal display apparatus in which display elements are etched out of silicon on a semiconductor disk and driver and actuator circuits are integrated onto the remaining webs is known from Japanese Application JP 3-100 516 A, with English abstract in Pat. Abstr. Jap., P-1229, Jul. 22, 1991, Vol. 15, No. 287. In this production method, the monocrystalline silicon disk is adhered by one side to a quartz disk and then ground down to a thickness of approximately 2 .mu.m. The display elements are subsequently etched out and the driver circuits are then integrated into the silicon webs. Afterward, display cell is completed.
A liquid crystal display element in which circuits and image element electrodes are also applied to the frame driver which remains after the etching out of the optical windows is also described in Japanese Application JP 4-128 717 A with English abstract in Pat. Abstr. Jap., P-1406, Aug. 20, 1992, Vol. 16, No. 393.
In the prior art known up to this point, no measures have been made known for integrating only the circuits in the production of AMLCDs in monocrystalline silicon.
SUMMARY OF THE INVENTION
According to the invention, the above object is achieved according to the present invention for an integrated active-matrix liquid crystal display of the type mentioned above by a method which comprises: with image point transistors and image point electrodes; by means of a structured mask, for later application of the light valves on the top side; filling with liquid crystals; an adhesive; employing a pattern created in a masking layer on the underside of the silicon disk, thereby to create recesses in the silicon disk which are permeable to light in the visual wavelength range; light valves; filter and on the top side with an electrode and an orientation layer; glass disk being maintained at a defined distance from the image point electrodes by spacers, and with a defined depth of the light valves being achieved by the spacers; and, filling the spaces with liquid crystals, and hermetically sealing the space.
In a wafer processed with the production methods known from microelectronics, the wafer including actuator electronics, image point transistors and electrodes, a standard method is used to produce small trenches on the surface of the
REFERENCES:
Salerno et al, "Single-Crystal Silicon Transmissive AMLCD", SID Digest, 1992, pp. 63-66.
A. Soederbaerg: "Investigation of Buried Etch Stop Layer in Silicon Made by Nitrogen Implantation". In: Journal of the Electrochemical Society, vol. 139, No. 2, Feb. 1992, Manchester, US, pp. 561-566.
Daimler-Benz Aktiengesellschaft
Powell William
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