JP2002182190A - Substrate with light shielding film and liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate with a light shielding film hardly causing defects such as pattern deflects. SOLUTION: In the substrate on which a light shielding film having a multilayered structure is formed, the uppermost layer of the light shielding film farthest from the substrate contains 40 to 80 atm.% chromium, 10 to 40 atm.% oxygen and 10 to 50 atm.% nitrogen, and the second layer adjacent to the uppermost layer contains 70 atm.% to <100 atm.% chromium and nitrogen with lower concentration than in the uppermost layer or contains 70 to 100 atm.% chromium and no nitrogen.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a substrate with a light-shielding film.

[0002]

2. Description of the Related Art In recent years, the backlight of a liquid crystal display (LCD) has been increased in brightness. For this reason, when the light reflectance of the liquid crystal side surface of the black matrix provided on the LCD substrate is high, there is a possibility that a problem such as malfunction of the TFT due to reflection of the backlight may occur. Therefore, low light reflection performance is also required for the liquid crystal side surface of the black matrix.

As a light shielding film for forming such a black matrix, Japanese Patent Application Laid-Open No. 2-144525 discloses a light shielding film in which a metal oxide film, a metal film, and a metal oxide film are laminated in this order on a substrate.

[0004]

However, such a 3
The light-shielding film with a layered structure has a metal oxide film whose etching rate is slower than that of a metal film, so that the cross-sectional shape after pattern formation by photolithography has an inverse taper between the metal oxide film and the metal film far from the substrate. Problem. FIG. 1 conceptually shows this state. A metal oxide film 2, a metal film 3, and a metal oxide film 4 are formed on a substrate 1. A reverse tapered portion 5 is formed between the two. Such a light-shielding film has a problem in that the pattern has a large unevenness at the edge portion of the pattern after the pattern is formed, and a defect such as a chipped pattern is likely to occur.

It is an object of the present invention to provide a substrate with a light-shielding film which solves this problem and has a low light reflectance and a good cross-sectional shape after pattern formation by photolithography.

[0006]

According to the present invention, there is provided a substrate provided with a light-shielding film having a multilayer light-shielding film formed on a substrate, wherein the uppermost layer of the light-shielding film furthest from the substrate is 40 to 80.
Atomic% chromium, 10-40 atomic% oxygen and 10-5
A second layer in contact with the uppermost layer, the second layer being in contact with the uppermost layer is a layer containing chromium of 70 to 100 atomic% and nitrogen having a lower concentration than the uppermost layer. A substrate with a film is provided. In addition, the second layer provides the substrate with a light-blocking film, wherein the second layer is a layer containing nitrogen having a concentration lower than that of the uppermost layer by 5 atomic% or more.

A light-shielding film provided with a light-shielding film having a multilayer structure formed on the substrate, wherein the uppermost layer of the light-shielding film farthest from the substrate is 40 to 80 atomic% of chromium, 10 to 80 atomic%.
A layer containing 40 atomic% of oxygen and 10 to 50 atomic% of nitrogen;
A substrate with a light-shielding film, characterized in that it is a layer containing chromium and no nitrogen.

Further, the visible light reflectance of the uppermost layer surface is 20%.
The following substrate with a light-shielding film is provided. In addition, a liquid crystal comprising: a liquid crystal cell using the substrate with a light-shielding film as a substrate on the viewer side; and a light source disposed in the vicinity of the liquid crystal cell on the side opposite to the viewer side. A display device is provided.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The light-shielding film of the substrate with a light-shielding film according to the present invention has a multilayer structure and includes at least an uppermost layer farthest from the substrate and a second layer in contact with the uppermost layer. May be provided between the second layer and the substrate. The top layer furthest from the substrate is 40-80 atomic% chromium,
The layer contains 10 to 40 atomic% of oxygen and 10 to 50 atomic% of nitrogen.

[0010] Nitrogen is an essential component for controlling the etching rate, and also has the effect of improving low light reflection performance.
If it is less than 10 atomic%, it is difficult to obtain such an effect.
It is more preferably at least 15 atomic%. On the other hand, if it exceeds 50 atomic%, the light-shielding properties tend to decrease. It is more preferably at most 40 at%, particularly preferably at most 20 at%.

Oxygen is used in an amount of 10 to ensure low light reflection performance.
At least atomic% is essential, and preferably at least 20 atomic%. On the other hand, if it exceeds 40 atomic%, the irregularities at the edges of the pattern after pattern formation become large, and defects such as chipping of the pattern tend to occur. It is preferably at most 30 at%, more preferably at most 25 at%. Although not essential, carbon can be added in a range of 20 atomic% or less. The visible light reflectance of the surface of the uppermost layer is preferably 20% or less (excluding the light reflectance of glass). From this viewpoint, it is effective to set the thickness to 10 to 70 nm.

The second layer in contact with the uppermost layer is a layer containing chromium of at least 70 atomic% and less than 100 atomic% and nitrogen having a lower concentration than the uppermost layer, or containing 70 to 100 atomic% of chromium, Is a layer that does not contain

[0013] Chromium is essential in an amount of 70 atomic% or more in order to secure light-shielding properties. Further, in order to prevent the light-shielding property of the second layer from lowering, the content of oxygen is set to 7 atom% or less, if any.
It is preferable that oxygen is not substantially contained, that is, except for the amount contained as an impurity.

[0014] Nitrogen is not essential, but containing it is effective for controlling the etching rate. However, the second layer must have a lower nitrogen concentration than the uppermost layer. In particular, it is preferable that the concentration of nitrogen in the second layer is lower than that of the uppermost layer by 5 atomic% or more in order to sufficiently prevent the taper from being reversely tapered. Also, although not essential, 10 atomic%
Carbon can be added in the following ranges. The thickness of the second layer is from 50 to 15 from the viewpoint of setting the OD (Optical Density: optical density) value in the visible region to 4.0 to 4.5.
It is preferably set to 0 nm.

The light-shielding film according to the present invention may include a third layer in contact with the second layer on the substrate side. The third layer preferably has the following composition in order to reduce the light reflectance as viewed from the substrate side. Chromium 30-80 atomic%, oxygen + nitrogen 20-70 atomic%.

In order to ensure low light reflection performance, it is preferable to contain either oxygen or nitrogen, and the concentration of each of oxygen and nitrogen is preferably 50 atomic% or less. Nitrogen is also effective in controlling the etching rate. Further, carbon is not essential, but can be added in a range of 20 atomic% or less. The thickness of the third layer is 30 to 70 nm from the viewpoint that the light reflectance in the visible region of the light-shielding film viewed from the substrate side is 3% or less (excluding the light reflectance of glass).
Is effective.

Each layer of the light-shielding film in the present invention can be produced, for example, by DC sputtering in a vacuum chamber using a target having an appropriate metal composition containing chromium as a main component.

When the second layer is formed, the atmosphere gas may be mainly Ar gas, and the tensile gas of the film can be reduced.
From the viewpoint of improving the adhesion and controlling the etching rate, a gas such as N ₂ may be mixed with the Ar gas, for example, in an amount of 40% by volume or less. The atmosphere gas when forming the uppermost layer, the Ar and N _2, a mixed gas of O ₂ or CO _2, such as by using a gas mixture of O ₂ or CO ₂ in N _2, these mixing ratios By optimizing and controlling the input power, a film having a desired composition can be formed.

If the substrate with a light-shielding film of the present invention is used as a substrate on the viewer side of a liquid crystal cell, and a light source is arranged near the liquid crystal cell on the side opposite to the viewer side, a liquid crystal display device is constructed.
This liquid crystal display device has an advantage that a TFT does not easily malfunction due to a light source.

[0020]

EXAMPLE As a transparent substrate, a transparent glass substrate having a thickness of 0.7 mm (alkali-free glass "AN100" manufactured by Asahi Glass Co., Ltd.)
After cleaning the surface of the glass substrate with a detergent to obtain a clean glass substrate surface, a light-shielding film having the composition and film thickness shown in Table 1 was formed using an in-line DC sputtering apparatus. The thickness of each layer was adjusted by adjusting the sputtering power.
The composition of each light-shielding film was measured by ESCA analysis. The balance of the composition is carbon. Examples 1, 2, and 3 are Examples, and Example 4 is a Comparative Example. All the light-shielding films in Table 1 had an OD value in the visible region of 4.0 or more. Further, each light shielding film was evaluated by the following method. The results are shown in Table 1.

(Patterned Shape) A positive resist (FH) is formed on the sample thin film using a normal photolithography process.
-2406: manufactured by Fuji Hunt Co.) was applied onto the light-shielding film with a spin coater, and exposed, developed and etched to pattern the light-shielding film. As the etching solution, a mixed solution containing 12% of ceric ammonium nitrate and 6% of perchloric acid on a mass percentage basis was used in the same manner as in the evaluation of the etching rate. When the etching time was optimized, the patterning with a line width of about 6 μm was possible, the pattern was difficult, and the pattern was difficult.

(Visible light reflectance) The visible light reflectance of the uppermost layer surface was measured using a spectrophotometer (CM2002 manufactured by Minolta). (Minimum light reflectance) The minimum light reflectance of the uppermost layer surface was measured using a spectrophotometer (CM2002 manufactured by Minolta).

[0023]

[Table 1]

[0024]

According to the substrate with a light-shielding film of the present invention, the cross-sectional shape of the substrate with the light-shielding film is unlikely to be reversely tapered after the patterning of the light-shielding film.
Defects such as chipped patterns are unlikely to occur.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram illustrating a problem of the related art.

[Explanation of symbols]

 1: substrate 2: metal oxide film 3: metal film 4: metal oxide film 5: reverse taper

Claims (5)

[Claims] 1. A light-shielding substrate having a light-shielding film having a multilayer structure formed on a substrate, wherein the uppermost layer of the light-shielding film farthest from the substrate is 40 to 80 atomic% of chromium and 10 to 40 atomic%. % Oxygen and 10 to 50 atomic% nitrogen, and the second layer which is in contact with the uppermost layer is a layer containing 70 to 100 atomic% chromium and nitrogen having a lower concentration than the uppermost layer. A substrate with a light-shielding film, characterized in that: 2. The substrate with a light-shielding film according to claim 1, wherein the second layer is a layer containing nitrogen having a concentration lower than that of the uppermost layer by 5 atomic% or more. 3. A light-shielding substrate with a light-shielding film having a multilayer structure formed on a substrate, wherein the uppermost layer of the light-shielding film furthest from the substrate is 40 to 80 atomic% of chromium and 10 to 40 atomic%. A second layer in contact with the uppermost layer is a layer containing 70 to 100 atomic% of chromium and not containing nitrogen. With board. 4. The substrate with a light-shielding film according to claim 1, wherein the visible light reflectance of the uppermost layer surface is 20% or less. 5. A liquid crystal cell using the substrate with a light-shielding film according to claim 1, 2, 3 or 4 as a substrate for a viewer, and a liquid crystal cell arranged near the viewer on the side opposite to the viewer. And a light source.