JPS633458A - Same size optical sensor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a same-magnification optical sensor in an image reading device or the like.

(Prior art) Amorphous silicon (hereinafter abbreviated as a-3i), C
In a life-size optical sensor that uses a semiconductor thin film such as dS and performs reading in close contact with an image plane, it has been proposed to use multilayer wiring in order to reduce the number of extraction electrodes. In devices using this multilayer wiring, when the light receiving part and the multilayer wiring part are formed on the same substrate, the size of the board is usually such that the length in the long side direction is equal to or larger than the reading width (for example, 210 nu for A4 size). (above), approximately 15 to 30 m in the short side direction. However, the part occupied by the light receiving part is in the short side direction,
It is only about 50 to 500 μm.

On the other hand, CVD,
A vacuum film forming apparatus such as PVD is used.

Therefore, in the production of a 1x optical sensor, this semiconductor film forming process takes the most time, which limits the overall productivity. In order to overcome this drawback, it is possible to form a large number of light-receiving parts at the same time in the second manufacturing process, but as mentioned above, the board, which occupies most of the area with the multilayer wiring part, can be placed in a vacuum apparatus. Productivity does not increase because it is set to . Therefore, it has been proposed to separate the substrates for the light receiving section and the wiring section and simultaneously producing a large number of only the light receiving sections.

However, if the light receiving section and the wiring section are manufactured separately in this way, it becomes necessary to electrically connect them later. The sensor element is usually 4 to 1 per 11 IIm.
Because they are arranged at a density of 6 dots, for example, A4 size (
210mm), requiring 840 to 3360 connections. In that case, a step, a gap, or the like occurs at the abutting portion between the substrate of the light receiving section and the substrate of the wiring section, which becomes a major cause of wire breakage.

FIG. 3 is a diagram schematically showing the joint between the substrate of the light receiving section and the substrate of the wiring section, and 1 is the substrate on which the light receiving section is formed;
A large number of sensor elements 2 are arranged in a line, and individual electrodes 3 are drawn out from each end. Reference numeral 4 denotes a substrate on which a multilayer wiring portion is formed, and wiring ends 5 to be connected to each individual electrode 3 extend therethrough. Therefore, the connection between these individual electrodes 3 and the wiring ends 5 becomes a problem.

(1) Lateral deviation: For example, if the line width at the end of the wiring is a and the line spacing is b, if the lateral deviation between the open substrates becomes b or more, it will come into contact with the adjacent individual electrode.

(2) Step difference at bonding surface: As shown in FIG. 3(b), if there is a large step difference greater than the film thickness at the end of the wiring between the open substrates, a state in which electrical connection is not achieved will occur.

No effective means for dealing with such wire breaks has been proposed so far.

(Objective of the Invention) The present invention solves the above-mentioned problems, and provides a same-magnification optical sensor that reliably connects the light receiving section and the wiring section.

(Structure of the Invention) A first substrate on which a large number of semiconductor light-receiving elements are formed and a second substrate on which wiring parts of the light-receiving elements are formed are arranged such that the element forming surface and the wiring part forming surface are substantially on the same plane. An interlayer insulating layer is formed across both substrates, and a wiring section is provided to connect the light-receiving element and the wiring section by passing over the interlayer insulating layer.

Hereinafter, embodiments will be described in detail with reference to the drawings.

(Example) FIG. 1 shows an example of the present invention. To explain it according to the basic manufacturing process, first, FIG. 1(a)
As shown in FIG. 1, a semiconductor hole 12 constituting a sensor element is formed on a substrate 11, and this is patterned. (In some cases, patterning is not necessary.) This substrate 11 is
The size can be reduced to the minimum area required to form the sensor element group. - On the other hand, a lower wiring 14 is formed on the substrate 13 constituting the multilayer wiring section.

Next, as shown in FIG. 1(b), both substrates 11 and 13 are butted against each other so that the element forming surface and the wiring forming surface are substantially on the same plane, and are bonded and fixed onto the holding substrate 15. . (Note that this step is not necessarily necessary.) After that, an interlayer insulating layer 16 is formed.

The glabella insulating layer 16 is 5in2. There are inorganic insulating films typified by Si3N4 and organic insulating films typified by polyimide resin. Of these, 5i02. Since Si and N4 are formed using a vacuum film forming apparatus such as plasma CVD or pyrolysis CVD, this goes against one of the objectives of the present invention, which is to reduce the substrate size and improve productivity. In order to further enhance the effects of the present invention, it is preferable to use an organic insulating film such as polyimide. Hereinafter, explanation will be given taking polyimide resin as an example.

Polyimide resin can be applied and formed into a film using a spinner, a roll coater, or the like. Further, this material is characterized by being able to flatten the unevenness of the substrate compared to the above-mentioned inorganic insulating film, and furthermore, it is easy to increase the film thickness.

This is an extremely important matter for the present invention. This will be explained with reference to FIG.

FIG. 2 shows an enlarged view of the joining portion of the side substrates, and when the substrate is normally made of glass, due to processing accuracy, for example, a plate having a thickness of 1 m includes a tolerance of 1 to 50 μm. Therefore, this level difference will always occur at the joint. In addition, if you cut two boards, form a light-receiving section on one side and a wiring section on the other, and then butt the cut surfaces together, even if the above-mentioned step does not occur, there will always be a chip at the end when cutting. etc., resulting in discontinuity at the joint surface. Although FIG. 2 shows a step at the bonding surface, in the present invention, this step can be filled with the interlayer insulating layer 16 and the surface can be made smooth.

By adjusting the viscosity of the varnish, the polyimide resin can be sufficiently thickened to about 100 μm. It is also known to impart photosensitivity,
After coating and pre-drying, it can be exposed to light in a desired shape and unnecessary parts can be removed. Furthermore, since it also functions as an adhesive, it can enter the gap between the side substrates and bond them together.

Finally, as shown in FIG. 1(c), on the interlayer insulating layer 16 with a smooth surface, the negative end becomes the individual electrode of the sensor element, and the other end is connected to the lower wiring 14 through the through hole. The wiring 17 and the common electrode 18 of the sensor element are formed, and a same-size sensor in which the peripheral substrates are reliably electrically connected is completed.

Next, a specific example of the above embodiment will be explained.

Thickness 1, Onm (tolerance 25.um), length 240
A semiconductor layer 12 made of a-3i was formed to a thickness of 1 μm by plasma CVD on a glass substrate 11 with a width of 7 nn, and then this semiconductor layer 12 was patterned so that each layer was 100 μm square. - On the other hand, the lower wiring 1 is placed on a glass substrate 13 with the same specifications but different only in width of 20 m.
4 was formed with AQ to a thickness of 1 μm. After that, holding board 1
When the substrates 11 and 13 were bonded and fixed to each other on the substrate 5, and the height difference between the side substrates 11 and 13 was measured, it was found to be 40 μm at the maximum.

Apply photosensitive polyimide pine resin to the surface of this side substrate 11.13 using a roll coater, dry it, perform exposure and development to remove the polyimide resin on the upper part of the semiconductor layer 12 and through-hole parts, and harden it at 300 ° C. Interlayer insulation layer 16
was formed. When the film thickness was examined in a bright room, it was found to be 43 μm.

Next, A9 was deposited on the entire surface to a thickness of 1.5 μm, and then patterned into a desired shape to explode a 1-size sensor.

There were no disconnections at all at the 1728 wiring connections at the junction between the substrates 11 and 13, and extremely reliable electrical connections could be obtained.

(Effects of the Invention) As explained above, according to the present invention, even if the light-receiving section and the wiring section are formed on separate substrates, electrical connection between the surrounding substrates can be ensured, and as a result, By reducing the area of the substrate constituting the light receiving section to the minimum necessary, productivity can be greatly improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an embodiment of the present invention together with a manufacturing method, FIG. 2 is an enlarged cross-sectional view of a board joint part, and FIG. 3 is a diagram showing a conventional board joint part. Figure 3 (b) is the third
It is a XX sectional view of figure (a). 11.13...Substrate, 12...Semiconductor layer, 14
... lower wiring, 15 ... holding substrate, 16 ... interlayer insulating layer, 17 ... upper wiring, 18 ... common electrode. Patent applicant: Ricoh Co., Ltd. Figure 1 Figure 3 (a) XP (b)

Claims (4)

[Claims] (1) A first substrate on which a large number of semiconductor light-receiving elements are formed, and wiring portions of the light-receiving elements are formed so that the wiring portion forming surface is substantially the same as the element forming surface of the first substrate. a second substrate coupled to the first substrate, an interlayer insulating layer formed across the first and second substrates, and the light receiving element and the wiring section passing over the interlayer insulating layer. 1. A life-sized optical sensor comprising: a wiring section for connecting the . (2) The interlayer insulating layer formed across the first and second substrates also serves as an adhesive at the joint between the first and second substrates. The same-magnification optical sensor described in (1). (3) The same-magnification optical sensor according to claim (1), wherein the interlayer insulating layer is made of polyimide or polyamide resin. (4) The same-magnification optical sensor according to claim (1), wherein the interlayer insulating layer has a thickness of 1 μm or more.