JPS6239062A - Contact type image sensor - Google Patents

Abstract

PURPOSE:To simplify the manufacturing processes, by realizing the two-layer wiring on a flexible wiring substrate while providing a wiring electrode consisting of a single layer on the insulating electrode. CONSTITUTION:An insulating substrate 301 is provided thereon with a wiring electrode 101, a lead-out electrode 102, a lower electrode 302 and an amorphous silicon layer 303. A transparent electrode 804 is further formed and a Schottky barrier is provided on the interface with the amorphous silicon 303. A protective film is formed for protecting the photo diode 201. An integrated circuit chip 305 of silicon resin is bonded on the substrate and a wire is bonded to the wiring electrode 101. The wiring electrode 101 is connected to the integrated circuit chip 305 and is also connected to a flexible wiring substrate 103 through the lead-out electrode 102. According to this construction, the step of forming an interlayer insulating film as well as the step of forming an upper electrode can be omitted. Further, the width of the insulating substrate can be decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of configuring a contact type image sensor that has a length that is approximately the same as the width of a document and that performs reading while coming into close contact with the document.

[Conventional technology]

Conventionally, facsimile document reading units or image readers have mainly used IC image sensors such as OCDs. In this case, in order to read a document with a width exceeding 200 mm using an IC image sensor with a width of 20 to 80 xx, a reduction optical system is required, and this is the main reason for hindering the miniaturization of devices such as facsimiles and image leagues. It had become. Recently, in order to solve these problems, a method has been proposed in which a document is read using a contact type image sensor that uses an amorphous semiconductor and has approximately the same size as the width of the document.

In this method, a rod lens array is used to form a royal life-size image of the document surface onto a photosensor array, so the optical path length is approximately 1,711, and the device can be significantly downsized.

FIG. 2 is a circuit diagram showing this type of contact type image sensor. For example, the IEICE technical research report OPM 8
g-42 (October 21, 1982).

In the figure, (20F) is a photodiode, (202
) is a common YFL tip (20B) (204) is a switch element, (205) is a buffer amplifier, (206) is a shift register, (207) is a start pulse input line, (
208), (209) and (210) are respectively -5V,
GND (ground), +5V power supply line, (2
11) is a clock supply line, (212) is a signal output line, (218) is a driving integrated circuit, and (2) is a signal output line.
14) is a serial data transfer line of the shift register (206) from the first integrated circuit to the (i+1)th integrated circuit.

Moreover, FIG. 3 is a plan view showing a conventional example of a contact type image sensor corresponding to the circuit diagram of FIG. 2, and FIG.
- It is a sectional view in the B' plane. In the figure, (801) is an insulating substrate, (+302) is a lower electrode, (1304) is a transparent electrode, (80B) is amorphous silicon, (805) is an integrated circuit chip, ([6) is a first electrode, (807) is an interlayer insulating film, (808) is a second electrode, (809) is a contact hole, (81(1) is a connection terminal part to an external circuit (not shown), (811) is the above-mentioned integrated circuit chip (305)
This is a bonding wire that connects the lower electrode (802''l) and the first electrode (806).

FIG. 5 is a timing chart showing waveforms of various parts for explaining the operation of the circuit configuration of the contact type image sensor shown in FIG. In the figure, (501) is the input waveform to the clock supply line (211), (502) is the input waveform to the start pass input line (207), (50B) is the shift register (206) Q1 output waveform, (504)
is the Q2 output waveform of the shift register (206), (50
5) shows the Q64 output waveform of the last integrated circuit, and (506) shows the waveform of the output signal line.

Next, the operation of the circuit configuration of the contact type image sensor shown in FIG. 2 will be described with reference to FIG. 5. first,
Attention will be paid to the first photodiode (201). The switch (208) connected to the cathode side of this photodiode (201) is closed when the Q2 output (504) of the shift register (206) becomes H level, and the switch (208) connected to the cathode side of the photodiode (201') is closed. A voltage of -6V is applied to both ends. At this time, the capacitance component cd (not shown) of the photodiode (201) is charged with charge qO (-cd×5). Next, when the Q2 output (504) of the shift register (206) becomes L level, the cathode side of the photodiode (201) is opened. On the other hand, light corresponding to the density of a read original (not shown) is input to the photodiode (201), and a photocurrent Ip flows in the direction shown by the arrow in FIG. The charges accumulated in the capacitor cd are discharged by this photocurrent Np. After the time TS shown in FIG. 5 has elapsed in this state, the voltage Vp between the terminals of the photodiode (201) is given by the following equation.

Q of the shift register (206) after the above time TS has elapsed.
When the l output (508) becomes H level, the switch element (204) connected to the output of the first buffer amplifier (205) is closed, and the output voltage V expressed by the following formula
O is output on the signal output line (212).

Assuming that the photocurrent Ip in the above equation (2) does not depend on the terminal voltage ■p of the photodiode (201), when the amount of light is constant, the above equation (2) becomes as follows, and the output The voltage VO is proportional to the amount of light.

Vo =-possible Ip Ts ゛--°°(3)
Therefore, as shown in FIG. 5, when a start pulse is input at a constant interval c period Ts), the output voltage Vo corresponding to the above equation (3) is chronologically applied to the signal output line (212) from the first term to the first term. is output to.

Next, a conventional construction method of such a contact image sensor will be explained using FIG. 8 and FIG. 4. All the circuit elements shown in the figure are mounted on a single insulating substrate (801). In other words, the photodiode (201) uses amorphous silicon (808) as the lower electrode ([2) and the transparent electrode (80
4) and has a sandwich structure.

In addition, a shift register (206), a switch element (2
An integrated circuit (218) consisting of 08) (204) and a buffer amplifier (205) is mounted as a chip on the same insulating substrate, and each terminal is bonded to the lower electrode (802) or the first electrode (806). wire (all)
connected with. Furthermore, the power supply line (208X
209) (210), clock supply line (211)
, the signal output line (212) is the first electrode (80F),
2 consisting of an interlayer insulating film (807) and a second electrode (808)
It is connected to each integrated circuit chip (805) using m wiring.

[Problem that the invention seeks to solve]

As described above, the conventional contact type image sensor has to use two-layer wiring for wiring between the integrated circuit chip (805) and the external circuit, and has the following problems.

(1) Since there is a two-layer wiring process, the number of steps increases.

(2) Poor contact at the contact hole portion and poor insulation of the interlayer insulating film occur, resulting in a decrease in yield.

The present invention was made to solve the above-mentioned problems, and aims to provide a contact image sensor that realizes the same wiring as the conventional one without using a two-layer wiring process.

[Means for solving problems]

The contact image sensor according to the present invention realizes two-layer wiring on a flexible wiring board, which was conventionally realized on an insulating substrate, and has a single layer of wiring electrodes on the insulating substrate.
Part or all of the wiring electrodes are electrically connected to a plurality of integrated circuit chips, and connected to the flexible wiring board at one location.

[Effect]

In this invention, by realizing two-layer wiring on a flexible wiring board, the formation of an interlayer insulating film and the formation of an upper electrode, which were conventionally necessary in the manufacturing process, are omitted. Furthermore, the width of the insulating substrate can be reduced.

Furthermore, by connecting the wiring electrodes to a plurality of integrated circuit chips, the number of connection types Wi to the flexible wiring board is reduced.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, (801) is an insulating substrate, (802) is a lower electrode, (808) is amorphous silicon, (804) is a transparent electrode, (201) is the lower electrode (802L amorphous silicon (808), and a photodiode grooved with a transparent electrode Ii (804), (805) an integrated circuit chip for driving the photodiode (201), (805)
11) is a bonding wire that electrically connects the integrated circuit chip (805) and the lower part to the pole (802) and the wiring electrode (101); (102) is the integrated circuit chip;
The lead electrode (1013) for wiring from t (805) is a flexible self-wire board that electrically connects the lead electrode (XO2) to an external circuit.

Further, FIG. 6 is a cross-sectional view taken along plane 7 of FIG. 1.

In the figures, the same reference numerals indicate the same parts.

The circuit diagram and operation of the contact type image sensor shown in this embodiment are the same as those of the conventional example described above.

Next, the manufacturing process of the contact type image sensor according to this embodiment will be described.

(2) Form a wiring electrode (101) and an extraction electrode (102) on an insulating substrate (801). Insulating substrate (801)
Includes alumina substrate, glazed alumina substrate (alumina substrate with glass glaze layer), glass plate, quartz plate,
etc. are appropriate. Wiring electrode (101), extraction electrode (1
02'')■ Since the line width can usually be made 0.In or more, it is preferable to use a printing/firing process of conductor paste.

(2) Form a lower electrode (802). The lower electrode (80
For 2), it is known that metal materials such as Cf and MO are effective because of the characteristics of the interface with amorphous silicon formed in the following process.

Therefore, as a process for forming the lower electrode, a thin film forming process such as sputtering or electron beam evaporation is suitable, and the lower electrode is patterned into the shape shown in the figure using a photolithography process.

■ Form amorphous silicon (808). Since it is necessary to reduce the localization rate of the amorphous silicon (8Q8), a glow discharge decomposition method is used.

As a method for forming the amorphous silicon (808) into the shape shown in the figure, it is preferable to use a photolithography process or a Manuk film formation process using a metal mask.

■ Form a transparent electrode (804). The transparent electrode (80
For 4), a so-called ITO film containing In 2 , Sn 2 , and 0 is suitable, and forms a Schottky barrier at the interface with the amorphous silicon.

■ Form a protective film (not shown). In order to protect the photodiode (201) formed in steps (2), (2), and (2), the photodiode is covered with silicone resin.

■ Mount an integrated circuit chip (805). An integrated circuit chip is adhered onto the substrate, and wire bonding is performed to the wiring electrode (101).

■ Protect the mounting part of the integrated circuit chip (805) with silicone resin.

Since the contact type image sensor according to this embodiment can be manufactured using the manufacturing process described above, the two-layer wiring process that was conventionally necessary can be omitted. Therefore, cost reduction becomes possible.

Mata, the figure is clear, +5V, GND,
-5V.

Wiring electrodes (101) corresponding to CLK and VOUT are connected to two integrated circuit chips (805) #1 and #2, and are connected to the flexible wiring board (108) with one lead-out electrode ( xo2).

By wiring in this way, the above-mentioned extraction electrode (102)
The pitch is approximately twice that of the case where one signal line of one integrated circuit chip (+305) is connected to the flexible wiring board with one lead electrode, and the pitch is approximately twice that of the case where one signal line of one integrated circuit chip (+305) is connected to the flexible wiring board (108). The alignment accuracy is relaxed and the assembly work time is shortened.

〔Effect of the invention〕

As described above, according to the present invention, the conventional insulating substrate (80
1) The manufacturing process can be simplified by eliminating the need for two-layer wiring, which was required on the top, and the width of the insulating substrate (BOX) can be reduced, making it possible to reduce the need for sputtering equipment and electron beams. Since the number of substrates on which films can be formed using an evaporation apparatus or a plasma CVD apparatus for glow discharge decomposition increases, it is possible to manufacture a contact image sensor at a very low cost.

Furthermore, since the wiring electrodes (101) connect multiple integrated circuit chips and one lead-out pole (102), the arrangement pitch of the lead-out electrodes (102) can be increased, and Another advantage is that alignment work between the electrode (102) and the flexible wiring board (10g) can be easily performed.

[Brief explanation of drawings]

FIG. 1 is a plan view showing a contact type image sensor according to an embodiment of the present invention, FIG. 2 is a general circuit diagram of a contact type image sensor, and FIG. 8 is a plan view showing a conventional contact type image sensor. FIG. 4 is a sectional view taken along the line B B' in FIG. 8, FIG. 6 is a time chart showing the operation of the contact image sensor, and FIG. 6 is a sectional view taken along line A-A' in FIG. 1. be. (201)...Photodiode, (105)...
...Integrated circuit chip, (101) ...Wiring electrode, (1
02)...Extraction electrode, (i08)...Flexible wiring board Note that the same reference numerals in the drawings indicate the same or corresponding parts.

Claims (1)

[Claims] An insulating substrate, a plurality of optical sensors disposed on the insulating substrate, an integrated circuit chip for driving the optical sensor, a plurality of wiring electrodes electrically connected to the integrated circuit chip, and the wiring. A flexible wiring board that connects the electrode and an external circuit is provided, and part or all of the wiring electrode is
A contact image sensor characterized in that it is electrically connected to a plurality of integrated circuit chips and further electrically connected to the flexible wiring board at one location.