JP2566910B2 - Flat sensor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a flat sensor which has particularly high sensitivity to light or heat and can be applied to position detection.

[Conventional technology]

The development of microprocessors and peripheral devices is remarkable, and in recent years, sensors have been connected to computers to automate measurement. In this case, conventionally, there are many methods in which a large number of optical semiconductors are arranged and their outputs are monitored, or a so-called flat digitizer is used to detect changes in pressure, capacity, and temperature and produce the position of the detection point. . These sensors are often considered as a collection of minute sensors, and many wires and ICs are required. On the other hand, inexpensive digitizers that do not require many ICs have been developed using conductive rubber. This is because the two conductive rubbers are separated by a spacer, and by applying pressure from above, the two rubbers above and below are electrically connected, and the two ends of the upper and lower conductive rubbers that occur at this time are connected. This is to read the change in electric potential or current value. Although this sensor using conductive rubber is cheap and simple, it has the disadvantages that it uses rubber, that a spacer is indispensable, and that it must be mechanically operated. To be Therefore, there were problems in use such as low detection accuracy, lack of stability, and slow response.

[Problems to be Solved by the Present Invention]

An object of the present invention is to improve response speed, detection accuracy, and stability that cannot be overcome by the above-mentioned conventional techniques.
According to the present invention, it is possible to obtain a stable flat sensor that is inexpensive and has a large area.

[Means for solving problems]

In the present invention, in order to increase the response speed, a semiconductor material whose physical properties are changed by light or heat is used without using mechanical force. In addition, in order to improve accuracy and stability, a method of uniformly depositing a semiconductor on the lower electrode was adopted in order to make the entire planar sensor a uniform structure, except for those that cause instability such as spacers. In addition, in order to suppress changes in the value of the current that flows in the semiconductor or changes in the potential of each part of the semiconductor during darkness or non-heating, a structure in which only a minute current flows even when a bias voltage is applied, that is, electrode / pinip
/ Adopted an electrode structure to suppress noise.

〔Example〕

An embodiment of the present invention will be described. A metal or a conductive compound is deposited as a lower electrode on an insulating substrate or a conductive substrate coated with an insulating material (hereinafter referred to as "substrate"), and the sheet resistance is 10 Ω / □ or more and 1 MΩ / □ or less, preferably 100 Ω / □ or more and 50 kΩ / □ or less. Semiconductors such as a-Se, CdSe, CdS, ZnO, ZnS that can be deposited over a large area on this substrate.
e, a-As ₂ S ₃ , a-selenium arsenic alloy, a-selenium tellurium alloy, organic semiconductor, a-silicon alloy, etc. are uniformly deposited in a thin film form. Here, "a-" means amorphous. Hereinafter, the semiconductor thus deposited is referred to as a "sensor section" in the sense that it plays a central role in detecting a signal.

Using a combination of materials capable of pn junction, pi
Deposition is performed so that a structure having at least one unit represented by -n-ip or n-i-i-n is obtained.
For example, with an amorphous silicon alloy, a pin structure can be easily created as in the case of a solar cell. By further depositing an ip structure on the p-i-n structure,
An -i-n-i-p structure can be created. Also, a-Se and CdSe
A to form a p-i-n-i-p structure, a-Se
The combination of CdSe and CdSe exhibits a rectifying action as in the example of a selenium rectifier. In this case, i-layer is not required and a-Se / CdS
The structure of e / a-Se may be used, but the withstand voltage characteristic may be slightly inferior. In addition, p-i-n- using polyxyltal silicon
The i-p structure can be easily enlarged. Alternatively, using microcrystal SiH (μc-SiH), p (a
-Si alloy) / i (a-Si alloy) / [mu] c-SiH / i (a-Si alloy) / p (a-Si alloy). In this case, the a-Si alloy is specifically a-Si: H, a-Si:
F: H, a-SiC: H, a-SiC: F: H, a-SiGe: H, a-SiGe:
F: H, a-SiSn: H, a-SiSn: F: H, a-SiN: H, a-SiN:
F: H, a-SiO: H, a-SiO: F: H and the like.

The upper electrode is deposited on the surface of the sensor unit, and the use of this electrode is related to the use of the base substrate and the lower electrode. That is, when used as an optical sensor, at least one of the substrate side and the upper side needs to be transparent or semitransparent. Therefore, for example, if light is taken in from the upper electrode side, the upper electrode needs to be transparent, and metal such as Cr,
Translucent Ni, Al, Ag, Au, Mg, Pt, Pb, Mo, Ir, Cu, etc., or conductive compounds such as ITO, ITO / SnO ₂ , SnO
_2. It is necessary to deposit cadmium tin oxide transparently or semi-transparently.

Fig. 1a shows the electrode / p-i-n thus prepared.
-I-p / electrode structure is shown.

A method of extracting the detection signal of the flat sensor will be described with reference to FIG. 1b. As shown in the figure, two opposite edges (3a) and (3b) of the lower electrode and two opposite edges (5a) and (5
b) Provide a total of four signal output lines, one each from and. As described above, the planar sensor of the present invention is characterized in that the number of signals taken out is very small and the device structure is simple. Further, when the flat sensor is used as a heat sensor instead of as an optical sensor, it is not necessary to irradiate light, and the electrode has a sheet resistance value of 10 Ω / □ to 1 MΩ / □, preferably 100 Ω / □ or more and 1 MΩ /
□ The following items are acceptable.

Specific examples will be described below, but the present invention is not limited thereto.

Example 1 Cr metal was vapor-deposited on a glass substrate (Corning 7059) by an electron beam vapor deposition method to prepare a conductive substrate having a sheet resistance of 600 Ω / □. Then, a glow discharge decomposition method
-SiH was deposited to have a p-i-n-i-p structure.

The conditions for glow discharge decomposition are: p layer: discharge power 30W substrate temperature 250 ° C SiH ₄ pressure 0.1Torr (40SCCM) 1000PPM B ₂ H ₆ / H ₂ pressure 0.2Torr (100SCCM) total pressure 0.3Torr deposition time 3 minutes i layer: Discharge power 40W Substrate temperature 250 ℃ SiH ₄ pressure 0.2Torr (80SCCM) Total pressure 0.2Torr Deposition time 20 minutes n layer: Discharge power 40W Substrate temperature 250 ℃ SiH ₄ pressure 0.1Torr (40SCCM) 1000PPM PH ₃ / H ₂ pressure 0.2Torr (100 SCCM) Total pressure 0.3 Torr Deposition time was 5 minutes. A CVD mask is placed on the lower electrode to prevent a-SiH from being deposited on the entire surface. This is to mask the signal extraction portion of the lower electrode. In this way, a glass / Cr / pin-ip structure was formed, and Cr was vapor-deposited on the surface of the uppermost p layer under substantially the same conditions as the base electrode. The sheet resistance of the upper Cr electrode is 560
It was Ω / □. The signal extraction part of the upper electrode was provided, and the flat sensor was completed.

He-Ne laser light was spot-irradiated on this flat sensor at a temperature of 20 ° C, and when the voltage change was observed by an oscilloscope, it was found that the response speed was sufficiently fast and the rise of the pulse response was 10 ms in the cathode ray tube. .

Next, when the heat resistance test of this sensor was performed
No significant change was observed in the performance after 100 hours at a high temperature of 200 ° C. The accuracy of the position sensor was confirmed while shifting the irradiation position of the He-Ne laser light, and it was found that even a displacement of the spot of 0.1 mm could be read by a 12-bit A / D converter. This has been found to be of sufficient accuracy compared to the prior art.

〔The invention's effect〕

As described above, by using the semiconductor, it is possible to obtain a large-area flat sensor having excellent stability, and by using this, it is possible to perform position detection with high responsiveness and high accuracy.

[Brief description of drawings]

FIG. 1a is a side view showing the structure of the flat sensor, and FIG. 1b is the same as above. (Main symbols in the drawing) (1): Substrate (2): Lower electrode (51): P-type semiconductor (52): i-type semiconductor (53): n-type semiconductor (54): i-type semiconductor (55): P Type semiconductor (6): Upper electrode

Claims (4)

(57) [Claims] 1. A lower electrode having a sheet resistance of 10 Ω / □ or more and 1 MΩ or less, a P-type semiconductor, an intrinsic semiconductor, an n-type semiconductor, an intrinsic semiconductor, and a P-type semiconductor are sequentially provided on a substrate, and the sheet resistance is provided thereon. Is provided with an upper electrode of 10 Ω / □ or more and 1 MΩ / □ or less, and a pair of extraction electrodes are arranged at two positions spaced apart from each other on the upper electrode,
A flat sensor, wherein another pair of extraction electrodes are arranged to face each other at a position that intersects with the two positions. 2. The P-type semiconductor is an amorphous silicon alloy containing a group III element, the intrinsic semiconductor is an amorphous silicon alloy, and the n-type semiconductor is an amorphous silicon alloy containing a group V element. The plane sensor described. 3. The value of the dark current flowing between the upper electrode and the lower electrode is 1 × 10 ⁻¹² A / cm ² or more under an applied voltage of 5 V and a temperature condition of 20 ° C. regardless of the polarity. × 10
The flat sensor according to claim 1, which is ^-2 A / cm ² or less. 4. The flat sensor according to claim 1, wherein at least one of the upper electrode and the lower electrode is an electrode transparent or semitransparent to light.