JPH01154034A - Nonlinear element - Google Patents

Abstract

PURPOSE:To uniformly for many nonlinear elements over a wide region with decreased defects by providing island-shaped protective parts consisting of a 1st conductor near the nonlinear elements in such a manner that the parts for forming the nonlinear elements consisting of the 1st conductor and the parts forming the protective parts are not electrically connected to each other. CONSTITUTION:An insulator TaOx 3 is formed in place between the 1st conductor Ta 1 and the 2nd conductor Cr 2 to form the MIM (metal-insulator-metal) element (nonlinear element). The protective part 4 is formed of Ta near the part (hatched part) where the MIM element consisting of the Ta 1 is formed, independently from the Ta which forms the MIM element part. Generation of the misregistration of the MIM element part and the protective part 4 by misalignment is obviated if the Ta is commonly used in the protective part 4. The parts where the MIM elements consisting of the Ta are to be formed are fined and uniformized in the case of patterning the Ta by etching. The fluctuation in the characteristics occurring in the nonuniformity in the shapes of the nonlinear elements and the defects such as exfoliation and breakage of a part of the films of the nonlinear elements are eliminated.

Description

[Detailed description of the invention] [Industrial application field] Regarding the structure of nonlinear elements.

[Conventional technology]

The structure of a conventional nonlinear element is shown in Figs. 3 and 4. Fig. 3 is a plan view of the nonlinear element and pixels when the nonlinear element is used to drive pixels of a liquid crystal display HR, and Fig. 4 3 is a sectional view of section bb' in FIG. 3. A known structure of a conventional nonlinear element is one in which a wEl conductor 1, an insulator 3, and a second conductor 2 are laminated, as shown in the FIS diagram or FIG. Here, the shaded area in FIG. 3 is a nonlinear element. The first conductor 1 is connected to the pixel electrode 5 via the insulator 3 and the second conductor 2. In particular, the structure of a nonlinear element with tJl in which the four-electric body 1 is Ta, the insulator 3 is a Ta oxide film (TaOx), and the second conductor 2 is Cr is well known.

[Problem that the invention seeks to solve]

However, in the above-mentioned conventional technology, the nonlinear element portion shown in FIGS. 3 and 4 (the shaded area in FIG. 3) is extremely fine, so the bump is generally 5 mm below, for example, and the nonlinear element is Due to variations in photoetching, which is the means of forming
It is difficult to manufacture nonlinear elements (usually about 100,000), and it has been difficult to increase the yield of liquid crystal display devices in which nonlinear elements are integrated.

Furthermore, if the second conductor 2 has poor adhesion to the substrate 6,
There were many defects such as the second conductor 2 being visible or broken on the substrate 6 (this made it difficult to increase the yield of, for example, a liquid crystal display device that integrates nonlinear elements.
When the conductor 1 is made of Ta, the second quadrielectric body 2 is made of Cr, and the substrate 6 is made of glass, and Ta, which is the first conductor 1, is etched by dry etching,
The adhesion between Cr, which is the second conductor 2, and glass, which is the substrate 6, is poor. Defects such as rips and cuts were noticeable.

This is because when patterning Ta, which is the first conductive film, by dry etching, the substrate glass is exposed to plasma, but the adhesiveness of the substrate glass exposed to plasma with the metal, which is a conductor, deteriorates. This is due to this.

The conventional technology had the above-mentioned problems. The present invention is intended to solve these problems, and its purpose is to form a large number of nonlinear elements uniformly over a wide area and with fewer defects. The objective is to improve the yield of liquid crystal display devices and the like.

Means for Solving Problem C] Nonlinear element foil of the present invention (1) - In a nonlinear element formed by laminating a first conductor, an insulator, and a second conductor on a substrate, An island-shaped protective portion made of a first conductor is provided in the vicinity, and a portion of the first four-electric body forming the nonlinear element and a portion forming the protective portion are not electrically connected. .

(2) The nonlinear element according to claim 1, wherein the insulator is a semiconductor.

〔Example〕

Embodiments of the present invention will be described below based on the drawings. FIG. 1 is a plan view of a nonlinear element according to the present invention, and is a plan view of a part of a nonlinear element and a pixel when the nonlinear element is used for driving pixels of a liquid crystal display device. FIG. 2 is a sectional view taken along aa' shown in FIG. An example of a nonlinear element is an MIM (metal, insulator, metal) element.

Examples will be described below based on an element structure that is particularly well known as an MIM element. The following description will be made based on the case where the first four-electric conductor is Ta1, the insulator is Ta oxide (hereinafter referred to as Ta0X), and the second conductor is Cr.

The inclined line portion in FIG. 1 forms a nonlinear element, and it is desirable for the area to be small in terms of element characteristics.

The nonlinear element is also a capacitor due to its structure. In terms of application, a small element capacitance is required from the viewpoint of electrical efficiency. This is generally well known. Furthermore, variations in the size of the elements directly lead to variations in the element characteristics, resulting in defects in reliability. It is desirable that the nonlinear elements be small and uniformly formed in large numbers.

In Figures 1 and 2, Taox3 is present between Tal and Cr2.
are used to form an MIM element, but Tal's MIM
A protective portion 4 of T2L is formed in the vicinity of the portion (shaded portion) where the device is formed, independently of the Ta forming the MIM device portion. If Ta is shared by the protection part 4, positional deviation between the MIM element part and the protection part due to misalignment will not occur. When Ta is patterned by etching, the portion of Ta where the MIM element will be formed is made finer and more uniform. This is due to the following reasons.

The portion of Ta that forms the MIM element is usually small, 5 μm or less, and other portions formed of Ta, such as the routing portions and terminal portions in liquid crystal display devices, are sufficiently small, and the resulting There is considerable variation in the design size of the patterns that must be formed in the same photoetching process, and the smallest part of the pattern is M.
The etching rate is the fastest in the area where the IM element is to be formed, and the variation in etching is also large. Regarding this variation, there are variations due to the etching itself and the location where the portion forming the MIM element is located. In the former case, for example, there are cases where the etching rate at the periphery of the substrate is high, and conversely, where the etching rate at the center of the substrate is high. In the latter case, for example, the etching rate may vary depending on whether some pattern exists or does not exist around the portion where the MIM element is formed, and if it does exist, its density and size.

Generally, when etching is performed with a resist attached to a pattern to be left, the etching rate becomes faster if no pattern is left around the pattern, and conversely, the etching rate becomes slower if a small pattern is left around the periphery. Therefore, in the case of liquid crystal display devices, even apart from variations in etching due to the process, the etching rate is fast in the area near the center of the screen, and slow in areas near the periphery of the screen. Generally speaking, the variation in MIM elements becomes larger, and this tendency becomes more pronounced as the MIM elements become finer.

Therefore, if a protection part 4 as shown in FIG. 1 or 2 is formed near the part where the Ta MIM element is formed (the shaded part in figure f!E1), the area near the Ta MIM element part will be No matter where the MIM element is on the board, the protection part 4
Because of this, the etching rate decreases and the uniformity improves. Naturally, the protection department (4) is M
The etching rate changes depending on the position from the IM element, and the closer it is, the slower the etching rate will be.Especially when Ta is etched by dry etching, the above tendency will not occur. growing.

Therefore, since it is possible to set the etching rate of Ta forming the MIM element portion with some degree of freedom, variations in the etching rate due to Ta pattern design and process can be reduced. In addition, when Cr2 has poor adhesion to the substrate 6, defects such as peeling or cutting of Cr2 from the substrate 6 occur, but if the structure shown in FIG. 1 or 2 is used, the above-mentioned defects can be reduced. This is effective when the adhesion between Cr and the substrate is poor but the adhesion between Cr and Ta is good. Especially when the substrate is glass,
This is noticeable when patterning of Ta is carried out by dry etching. The above reasons are shown below.

Etching of Tal is generally performed by dry etching. At this time, the glass substrate exposed to etching gas plasma (e.g. COF radicals) has poor adhesion to the metal. Therefore, Cr2 has poor adhesion to the substrate 6. Also, Cr is used for miniaturization of MIM elements. From this point of view, the part where the MIM element is formed must be extremely thin, 5 μm or less.Furthermore, due to the problem of alignment accuracy with Ta, the part where the element is formed must be made with consideration for alignment accuracy as shown in Figures 1 and 3. Therefore, in the past, the Cr part had to be formed on glass with poor adhesion, and there were many defects such as peeling and cutting, especially in the thin part.As shown in Figure 1. If the protective part 4 is formed of Tal as shown in the figure, the area where Cr must be formed in a thin and poor adhesion area is narrow (,
By widening the Cr pattern on the protective portion 4, Cr can be formed in the widest possible pattern in areas where adhesion is poor.

This makes it possible to narrow the area where Cr is broken or broken, thereby reducing these defects.

In the embodiment shown in FIG. 6, the area of the protective portion 4 shown in FIG. 1 is increased to further enhance the adhesion of Cr.

The embodiment of FIG. 6 has a substrate 6, T a 1 , and Cr2
Substrate 6 before forming Tal to improve adhesion with
An insulator is formed on top as a base. For example, the insulator may be Ta oxide (TaOx). Normally, Taxi is also etched when forming a Ta pattern. If the etching is done uniformly, only the Ta pattern will be etched, leaving the underlying TaOx.
Although it is possible to improve the adhesion with Cr, etching is generally not performed uniformly due to variations in the process and the influence of the Ta baton. Therefore, it is common practice to perform etching in accordance with the part where the etching rate is slowest, and usually no underlying TaOx remains in the vicinity of the part where the MIM element is to be formed, that is, in the part where Cr adhesion is desired to be improved. This is simply because the underlying TaOx is used to enhance the adhesion between Ta and the glass substrate. Here, if the protective part 4 is formed near the MIM element forming part at the same time as the Ta baton is formed, the protective part 4 and the MIM
The etching rate slows down in the area between the M element formation areas, and the underlying insulating film remains in the areas where Cr is thin and where you want to improve adhesion, increasing Cr adhesion, resulting in Cr separation and Cr
This will reduce breakage and the like.

The embodiment shown in FIG. 7 is an embodiment in which Cr and the shape of the protection part 4 are changed. The area efficiency of the element is good.

Furthermore, it is known that a device in which the insulator 3 is a semiconductor film also becomes a nonlinear element and has a similar effect.

FIG. 8 shows an embodiment in which the stacking positions of the first conductor and the second conductor are interchanged.

FIG. 9 is similar to FIG. 5 in another embodiment.

〔Effect of the invention〕

As described above, the present invention solves the conventional problem of unevenness in characteristics due to non-uniformity of the shape of the nonlinear elements in the case of liquid crystal display devices, etc., in which a large number of nonlinear elements are formed over a wide area. , it is possible to solve the problem that the yield cannot be increased due to defects such as peeling or cutting of a part of the film of the nonlinear element.

This has the effect that, for example, a liquid crystal display device, etc., in which a large number of nonlinear elements are uniformly integrated over a wide area, can be produced with good quality and high yield.

Furthermore, since the structure of the present invention can be achieved by simply changing the layers that already exist, the cost is no different from conventional products, which is an essential element for mass production.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a nonlinear element according to an embodiment of the present invention. FIG. 2 is a sectional view of a nonlinear element according to an embodiment of the present invention. FIG. 3 is a plan view of a conventional nonlinear element. FIG. 4 is a cross-sectional view of a conventional nonlinear element. FIG. 5 is a plan view of a nonlinear element according to an embodiment of the present invention. FIG. 6 is a sectional view of a nonlinear element according to an embodiment of the present invention. FIG. 7 is a plan view of a nonlinear element according to an embodiment of the present invention. FIG. 8 is a plan view of a nonlinear element according to an embodiment of the present invention. FIG. 9 is a plan view of a nonlinear element according to an embodiment of the present invention. 1... First conductor (Ta) 2...Second conductor (Cr) 3... Insulator (TaOx) 4...Protection section 5... Pixel electrode 6... Board that's all Applicant: Seiko Epson Corporation Figure 1 Figure 3 Figure 5 Figure 6 Figure 8

Claims (2)

[Claims] (1) In a nonlinear element formed by laminating a first conductor, an insulator, and a second conductor on a substrate, an island-shaped protection part made of the first conductor is provided near the nonlinear element, and the first A nonlinear element characterized in that a portion of the conductor forming the nonlinear element and a portion forming the protection portion are not electrically connected. (2) The nonlinear element according to claim 1, wherein the insulator is a semiconductor.