JPH0764130A - Variable photomask - Google Patents

Abstract

PURPOSE:To provide a variable photomask which is variable in patterns. CONSTITUTION:A mask pixel has a switching material film 12 on a light input transparent cover glass 10 side, is laminated with a photodetecting material film 14 in the lower part and has electrode films 16, 18 on the front and rear surfaces. A transparent electrode film 16 on the front surface is coupled to the source side of a switching transistor(TR) 20. A lead line 24 for switching on an Si substrate 22 is coupled to the gate electrode of the switching TR 20. A reading out line 26 is coupled to the drain of the switching TR 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable optical mask which can be used in an optical signal processing device having a combination of a mask and a sensor and which can change a mask pattern.

[0002]

2. Description of the Related Art Recently, light is used as a carrier.
The development of information processing technology has become more and more active. One of the reasons is that the obstacle caused by using electrons as carriers increases as the processing speed increases. However, the processing technology for switching the flow of electrons and performing logical processing based on the semiconductor technology is enormously accumulated, including in computers. The latter of the two advantages of high-density integration and high-speed processing that are characteristic of the electronic processing technology, that is, the high-speed processing, has come to a limit because of obstacles caused by using electrons as carriers. This makes optical technology development urgent. The main point of optical technology development is finally moving to the development of materials for logic processing or systems using the functions of materials.

For example, a phenomenon utilized in optical switching technology is nonlinear absorption or reflection of light due to third-order optical nonlinear effect due to exciton generation. The material used is a transparent body, such as glass, containing compound semiconductors or ultrafine particles of compounds that generate excitons. The most developed optical switching technology is the remarkable AT & T SEED (s) that utilizes the nonlinearity due to the Stark effect of excitons confined in the exciton level of a compound semiconductor multiple quantum well structure.
elf-eleotopic effect dev
ice).

Further, there is a PNPN junction thyristor structure for performing light / electricity / light conversion in a chip and indirectly switching light. In this device, the light emission threshold of the thyristor is controlled by light. A typical example is VSTEP manufactured by NEC Corporation.

The liquid crystal used as a display is a typical spatial modulation element, but one electrode surface of the liquid crystal pixel is mirror-finished to form a light-reflecting surface, and optical switching can be realized by the presence or absence of reflected light. .

[0006]

The function of the optical switching device according to the prior art has been confirmed as a single element, but a two-dimensional array is under development in many cases.

Further, the practically usable SEED array has a problem that the ratio of light transmission to absorption or reflection is small.

Further, the conventional optical switching device has a complicated structure except for the liquid crystal optical switching device. Therefore, there is a drawback that it becomes expensive.

Further, the liquid crystal optical switching device is
Since the structure is not complicated, it is inexpensive, but it has a drawback that the response speed is slow.

Further, in the current technology, there is no element that controls an electric signal by light except a phototransistor. Therefore, for the time being (probably 10 years), the final signal output will be an electrical signal. Therefore, for some systems it may be more efficient to convert the optical signal to an electrical signal at an early processing stage.

A combination of a mask and a sensor in a broad sense is generally used to selectively convert a large number of light beam bundles carrying signals into an electric signal. However, at present, the pattern of the selective light transmission mask is fixed.

It is an object of the present invention to provide a variable light mask which has substantially the same function as the selective light transmission mask and which can change the mask pattern.

[0013]

SUMMARY OF THE INVENTION In the present invention, the photodetector element voltage generated in each mask pixel is switched by a material whose conductivity is controlled by an optical signal. That is, conductivity is imparted to the bright mask pixels by the mask pattern forming light, and the presence or absence of light input is read by the output of the photodetector. On the other hand, a dark pixel has no electrical output because it does not have conductivity, regardless of the presence or absence of light input. Therefore, mask pattern creation light (first light) is selectively applied to each of the mask pixels.
Is applied to give a conductivity to form a mask, and the mask pattern is erased by the second light as needed, and a new mask pattern is newly made by the first light. A variable photomask can be obtained by repeating this operation at appropriate times.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is a variable optical mask using a polycrystal of a material obtained by adding a transition metal atom as an impurity to a dielectric or ferroelectric material, and a thin film of a single crystal material as a functional material if desired. When this functional material is irradiated with light of a specific wavelength (first light), the conductivity of the material increases, and when irradiated with another specific wavelength (second light), the conductivity is restored to the original conductivity. In particular, the Cr-doped Bi ₂ O ₃ thin film shows remarkable characteristics.

The characteristics of Cr-doped Bi ₂ O ₃ will be described.

First, the change in conductivity due to laser irradiation will be described.

Cr ₂ O ₃ was added in an amount of 0.1 wt% and 0.
Dielectric material Bi containing 01 wt% and 0.001 wt%
₂ O ₃ is prepared and Ar of 488 nm wavelength is prepared for each.
Irradiate the laser (about 2.54 eV), then 632.
Changes in conductivity when irradiated with a He-Ne laser having a wavelength of 8 nm (about 1.96 eV) are shown in FIGS. 1, 2 and 3.

In any of the Cr ₂ O ₃ -containing materials, the conductivity is drastically changed by Ar laser irradiation.
However, there is a difference in the change due to the subsequent irradiation with He-Ne laser. In FIG. 1, the original conductivity is restored, but in FIGS. 2 and 3, the restoration speed is not fast.

Next, the change in structure due to the Cr ₂ O ₃ content will be described.

FIG. 4 shows Bi containing 1 wt% of Cr ₂ O ₃ .
₂ shows the photocurrent of O ₃ . A material containing no impurities has a photoconductivity spectrum in the vicinity of the band gap Eg.
A material containing 1 wt% shows a wide photoconductive property,
A compound of i ₁₈ CrO ₃₀ is produced. When the compound is formed, the electron level due to impurities becomes uncontrollable and the expected properties are lost.

Next, the change in structure due to heat treatment will be described.

5 and 6, the substrate temperature during growth is 250.degree.
It shows photoconductivity at 300 ° C. According to these figures,
At a substrate temperature of 300 ° C., no light emission is observed in the 2-3 eV band. That is, the impurity Cr is stably taken into the structure, and the impurity addition Bi ₂ O ₃ is eliminated. It can be seen that the structure of the dielectric material Bi ₂ O ₃ must be maintained in order to obtain the expected characteristics.

Next, the structure of a mask pixel using a Cr-doped Bi ₂ O ₃ thin film as a switching material film will be described.

FIG. 7 shows the structure of the mask pixel. This is a multi-functional film having a switching material film 12 on the upper surface, that is, the light input transparent cover glass 10 side, a photo detection material film 14 laminated on the lower side, and electrode films 16 and 18 on the upper and lower surfaces. The transparent electrode film 16 on the upper surface is the switching transistor 20.
Coupled with the source side of. The switching lead line 24 on the Si substrate 22 is
It is coupled to the gate electrode of transistor 20. Also,
Readout line 26 is coupled to the drain of switching transistor 20. In FIG. 7, 28 is S
The iO ₂ film, 29 is a circuit board.

FIG. 8 shows a two-dimensional pixel array in which the mask pixels of FIG. 7 are arranged in a matrix on a circuit board. Only four pixels are shown for simplicity of illustration.

The drain of switching transistor 20 is coupled to read line 26, the source is coupled to transparent electrode film 16, and the gate is coupled to switching lead line 24. In FIG. 8, 30 is the electrode film 1.
6 shows a functional film composed of the switching material film 12 and the photodetection material layer 14 between the electrode 6 and the electrode film 18. Also,
The lower electrode 18 of the light detection material film 14 is connected to the common electrode line 31 via the functional film 30. The electrons switched by the gate voltage of the transistor 20 are
It is output in the column direction by the read line 26.

FIG. 9 shows an equivalent circuit of the mask pixel. In the figure, a portion 32 surrounded by a dotted line is a switching portion of the mask pixel. The switching unit 32 includes a P-MOS transistor 34 showing a switching material film (Cr-doped Bi ₂ O ₃ ), a capacitor 36, a photodiode 38,
Equivalently represented by 40. Writing light (forming light) for the mask pattern is input to the photodiode 38. The mask pattern erasing light is input to the photodiode 40.

The read switching transistor 20 is connected to one terminal of the P-MOS transistor 34, and the photodiode 42 is connected to the other terminal of the P-MOS transistor 34. It is connected via a power supply 44. In addition, the photodiode 3 of the switching unit 32
Reference numerals 8 and 40 are connected to both ends of a DC power supply 44. The photodiode 42 is an equivalent circuit of the light detection material film 14, and the input light to the mask pixel is input.

The writing light charges the capacitor 36, causing the gate of the P-MOS transistor 34 representing the switching material film to go high. Therefore, when the input light is irradiated, the input signal is output through the read switch 20 by the read signal. If there is no input light, there is no output regardless of whether the read switch 20 is open or closed. If the writing light is not irradiated, the P-MOS transistor is low and there is no output regardless of the presence or absence of the input light. The charged electric charge of the capacitor 36 is discharged by irradiating the photodiode 40 with erasing light, and the gate of the P-MOS transistor 34 becomes low.

FIG. 10 is an overall block diagram of a variable light mask panel. A row selector 50 and a column selector 52 are connected to the circuit board 30 of the pixel array, and these are controlled by a controller 54. The row selector 50 is
The switching lead line 24 in FIG. 8 is selected. The column selector 52 selects the read line 26 of FIG.

A mask pattern is formed by making the mask forming light incident on the cover glass 10 of the pixel array to make the switching material film 12 of the pixel conductive.

The light source for the mask pattern forming light and the input light can be constituted by a pixel-based light emitting element array provided on the front surface of the cover glass 10. The optical axis of the creation light may be coaxial with the input light or may be a tilted input. The bright and dark pixel address of the mask pattern is input to the controller 54. Now, in synchronization with the row selection of the mask panel, the rows of the writing light array are selected, the column address of each row is selected according to the mask pattern, and the writing light is turned on to form the mask pattern.

The pixel array after forming the mask pattern is irradiated with the input light, and the light detection signal by the light detection material film 14 is
The row selector 50, which is driven in synchronization with the incident light, scans the switching line 24 and turns on the read switch 20 to perform reading. The read light detection signal is
The column selector 52 scans the read line 26 and is taken out in parallel as an output signal from the column selector 52. The scanning operations of the row selector 50 and the column selector 52 are
This is performed by inputting the row address and the column address from the controller 54.

To erase the created pattern, irradiation with erasing light is performed. When using the same pattern for a long time, refresh with pattern forming light at appropriate times.

As another example of the light incident method, a case of using a liquid crystal shutter and selecting light will be described.

A transmissive liquid crystal shutter (not shown) is arranged in front of each mask pixel. The controller 54 opens and closes the shutter pixels.

The mask pixel to which light is applied, that is, which shutter pixel to open, is set by setting the pixel address by the controller 54. Although not shown, the liquid crystal shutter is opened and closed by a processing circuit similar to signal reading.

The light for forming the pattern and the light for erasing the pattern are input by opening and closing the liquid crystal shutter to select the light incident on the entire surface of the liquid crystal. Signal light is input by opening the entire liquid crystal.

[0039]

According to the present invention, it is possible to realize a variable optical mask which can be used in an optical signal processing apparatus having a combination of a mask and a sensor and which can generate an arbitrary mask pattern at high speed.

The variable photomask of the present invention is a semiconductor chip size digital mask. Generally, it is desirable that the size of the carrier beam in the optical signal processing is as small as possible in view of competition with the electronic signal processing, and the pixel shape must be highly accurate. In the present invention, the light receiving unit of the light beam is determined by the size of the electrode, and the size is several 100 μm. Since the processing of such a digital mask is performed on the Si substrate by the semiconductor processing technology, it is highly accurate.

Further, according to the variable photomask of the present invention, each pixel is individually read by the scanning circuit and the processing such as sum of products is performed as digital information, so that highly accurate reading can be performed.

[Brief description of drawings]

FIG. 1 is a diagram showing a change in conductivity of Bi ₂ O ₃ containing Cr ₂ O ₃ by laser irradiation.

FIG. 2 is a diagram showing a change in conductivity of Bi ₂ O ₃ containing Cr ₂ O ₃ by laser irradiation.

FIG. 3 is a diagram showing a change in conductivity of Bi ₂ O ₃ containing Cr ₂ O ₃ by laser irradiation.

FIG. 4 is a diagram showing a photocurrent of Bi ₂ O ₃ containing Cr ₂ O ₃ .

FIG. 5 is a diagram showing photoconductivity when the substrate temperature during growth of Bi ₂ O ₃ containing Bi ₂ O ₃ or Cr is changed.

FIG. 6 is a diagram showing photoconductivity when the substrate temperature during growth of Bi ₂ O ₃ containing Bi ₂ O ₃ or Cr is changed.

FIG. 7 is a diagram showing a structure of a mask pixel.

FIG. 8 is a diagram showing a two-dimensional pixel array.

FIG. 9 is a diagram showing an equivalent circuit of a mask pixel.

FIG. 10 is an overall configuration diagram of a variable light mask panel.

[Explanation of symbols]

10 cover glass 12 switching material film 14 photodetection material film 18 electrode 22 Si substrate 24 switching lead line 26 read line 28 SiO ₂ film 29 circuit board 50 row selector 52 column selector 54 controller

Claims (7)

[Claims] 1. A plurality of mask pixels, each of which has a photodetector and a switching element for switching an output voltage of the photodetector and capable of controlling conductivity by an optical signal, are arranged two-dimensionally. Characteristic variable light mask. 2. The switching element is made of a functional material whose conductivity increases when irradiated with light of a certain wavelength and which returns to its original conductivity when irradiated with light of another wavelength. 1. The variable light mask described in 1. 3. The variable optical mask according to claim 2, wherein the functional material is a polycrystal or single crystal material of a material obtained by adding a transition metal atom as an impurity to a dielectric material or a ferroelectric material. 4. The variable photomask according to claim ₂ , wherein the functional material is Cr-doped Bi ₂ O ₃ . 5. A variable characterized in that a switching material film and a photo-detecting material film are laminated, a composite function film having electrodes on both surfaces is used as a mask pixel, and a plurality of mask pixels are arranged two-dimensionally. Light mask. 6. The mask pixel includes a read circuit having a switch element, one end of which is connected to an electrode of the composite functional film, the other end of which is connected to a read line, and a control terminal of which is connected to a switching lead line. The variable photomask according to claim 5, wherein: 7. A row selector that scans a plurality of the switching read lines, a column selector that scans a plurality of the read lines, and a controller that inputs a row address and a column address to the row selector and the column selector, respectively. 7. The variable photomask according to claim 6, further comprising: