# US 5,349,456 A · Substrate having an active element array with low hydroxyl and chlorine

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- Number: US 5,349,456 A
- Document ID: US5349456A
- Status: Granted
- Kind: A
- Application number: 08/009,677
- Filed: 1993-01-27
- Granted: 1994-09-20
- Earliest claimed: 1992-01-31
- Assignees: Sony Corporation
- Inventors: Toshihiko Iwanaga; Kazuyoshi Yoshida; Takusei Sato
- Web page: https://patentgrep.com/patent/US5349456A

## CPC

- G02F 1/1333: Constructional arrangements; {Manufacturing methods}(G02F1/135, G02F1/136 take precedence)
- C03C 3/06: with more than 90% silica by weight, e.g. quartz {(C03C3/045 takes precedence)}
- C03C 2201/11: containing chlorine
- C03C 2201/23: containing hydroxyl groups
- C03C 2201/32: containing aluminium (C03C2201/36 takes precedence)
- C03C 2201/50: containing alkali metals
- C03C 2203/40: Gas-phase processes
- G02F 1/1368: in which the switching element is a three-electrode device {(G02F1/136277 takes precedence)}
- Y10S 501/90: Optical glass, e.g. silent on refractive index and/or ABBE number
- G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- C03C: CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

A synthetic quartz glass substrate (1) supporting active elements is formed of high-purity synthetic quartz glass having, a hydroxyl group content of 200 ppm or below and chlorine group content of 50 ppm or below. The substrate (1) may have an impurity level of 1 ppm or less sodium and 1 ppm or less aluminum. TFTs (6), i.e., active elements, and picture element electrodes (7) are formed on the surface of the synthetic quartz glass substrate (1) to construct a driving panel for a liquid crystal display of an active matrix type. A liquid crystal panel is formed by disposing the driving panel and a counter substrate (2) opposite to each other and sandwiching a liquid crystal layer (3) between the driving panel and the counter substrate (2).

## Claims

### Claim 1

A substrate having an active element array comprising:
a glass substrate composed of synthetic quartz glass including a hydroxyl group whose concentration is 200 ppm or less and a chlorine group whose concentration is 50 ppm or less.

### Claim 2 (depends on 1)

A substrate as claimed in claim 1, wherein said synthetic quartz glass includes impurities of 0.1 ppm or less of sodium and 1 ppm or less of aluminum.

### Claim 3 (depends on 2)

A substrate as claimed in claim 2, wherein said active element array comprises a thin-film transistor array.

### Claim 4 (depends on 1)

A substrate as claimed in claim 1, wherein said active element array comprises a thin-film transistor array.

### Claim 5

An electrooptical device comprising:
a glass substrate composed of synthetic quartz glass including a hydroxyl group whose concentration is 200 ppm or less and a chlorine group whose concentration is 50 ppm or less;
a plurality of picture element electrodes disposed in the matrix form, each picture element electrode being associated with a switching element;
an insulating substrate placed opposite to and spaced apart from the glass substrate; and
an electrooptical material layer sandwiched between the glass substrate and the insulating substrate.

### Claim 6 (depends on 5)

An electrooptical device as claimed in claim 5, wherein said synthetic quartz glass includes impurities of 0.1 ppm or less of sodium and 1 ppm or less of aluminum.

### Claim 7 (depends on 5)

An electrooptical device as claimed in claim 5, wherein said switching element is a thin film transistor.

### Claim 8 (depends on 7)

An electrooptical device as claimed in claim 7, wherein said thin-film transistor comprises a thin film of polycrystalline silicon.

### Claim 9 (depends on 5)

An electrooptical device as claimed in claim 5, wherein said electrooptical material is liquid crystal.

### Claim 10 (depends on 5)

An electrooptical device as claimed in claim 5, wherein said glass substrate has a thickness of 1 mm or less.