JP3194274B2 - Method for manufacturing active matrix type liquid crystal display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an MIM liquid crystal display device.
In particular, it relates to a method for manufacturing an MIM element.

[0002]

2. Description of the Related Art Heretofore, an MIM liquid crystal display device using an MIM element has a small capacitance ratio between the MIM element and its driving liquid crystal. The non-linearity of the IV characteristic of the MIM element is poor. Large MIM element has a problem that the polarity difference of the IV characteristic is large.
Display contrast and its temperature characteristics are inferior to T liquid crystal display devices, high-definition display and pixel division redundancy cannot be performed,
There were problems such as afterimages on the display. However, recently, as shown below, research and development on MIM elements have progressed, and these problems are being solved.

[0003] The MIM element insulating film is doped with N, and the element capacitance, I−
Improves nonlinearity of V characteristic and leakage current MIM element has lateral structure and element capacitance, IV
Nonlinearity characteristics, the conventional method of manufacturing a N-doped MIM element to improve the polarity difference with the I-V characteristic of the MIM element of improving the leakage current to the serial structure, for example, from TaO _X or TaO _X N _Y on the substrate A first step of forming a base insulating film, and a second step of reactively sputtering Ta on the base insulating film in an atmosphere containing N ₂ .
A third step in which the film formed in the second step is chemically dry-etched in an atmosphere containing CF ₄ and O ₂ and patterned into a lower electrode;
A fourth step of forming an element insulating film by anodizing the lower electrode, a fifth step of forming a conductive film on the element insulating film, and etching the conductive film on an upper electrode. It had a sixth step of patterning.

In a conventional method for manufacturing a lateral MIM element, a first step of forming a base insulating film made of , for example , TaO _X or TaO _X N _Y on a substrate, and forming Ta on the base insulating film. A second step, a third step of subjecting the film formed in the second step to chemical dry etching in an atmosphere containing CF ₄ and O ₂ and patterning the lower electrode, and anodizing the lower electrode to form a barrier insulating film A fourth step of forming
A fifth step of chemically dry-etching and removing a part of the barrier insulating film in an atmosphere containing CF ₄ and O ₂ , and a _second step of forming an element insulating film by anodizing the etched portion of the barrier insulating film again. Six steps, a seventh step of forming a conductive film on the element insulating film of the sixth step, and an eighth step of etching and patterning the conductive film on an upper electrode to form a MIM element I was

[0005] method of manufacturing a conventional serial MIM element, for example a forming a first step of forming an underlying insulating film formed of TaO _X or TaO _X N _Y on the substrate, a Ta on the underlying insulating film Step 2, a third step in which the film formed in the second step is chemically dry-etched in an atmosphere containing CF ₄ and O ₂ and patterned into a lower electrode, and the lower electrode is anodized to form an element insulating film. A fourth step of forming, and a fifth step of forming a conductive film on the element insulating film of the fourth step.
A sixth step of forming an MIM element by etching and patterning the conductive film on an upper electrode, and forming a part of the element insulating film and a lower electrode thereunder in an atmosphere containing CF ₄ and O _2. There was a seventh step of chemical dry etching, removal and separation.

[0006]

However, the above-mentioned prior art has the following problems.

When N-doped Ta is chemically dry-etched in an atmosphere containing CF ₄ and O ₂ , countless white fine powder is generated on the substrate during the etching, so that Ta remains and the upper electrode tends to be cut. This is because when the Ta film is etched, N in the Ta film reacts with O _{2 of the} etching gas and changes to nitrate ions, which are etching products of Ta and have a relatively high vapor pressure. This is a phenomenon caused by changing TAF ₅ which is easily evacuated to TaO ₂ F having a low vapor pressure.

[0008] Ta, TaO _X or TaO _{X NY} is converted to CF ₄ and O
When chemical dry etching in an atmosphere containing _2,
During etching, very fine etching products redeposit on the substrate. Conventional lateral MIM element or serial M
Many dry etching steps are performed in the manufacturing process of the IM device, and an increase in leak current due to the influence of re-deposition cannot be ignored. Further, dry etching has a low process throughput, leading to an increase in cost.

Conventional lateral MIM elements and serial M
The IM device requires more manufacturing steps than a normal MIM device, which increases the manufacturing cost.

Therefore, the present invention solves these problems, and aims at high production yield.
An object of the present invention is to obtain a low-cost high-quality MIM display.

[0011]

According to a method of manufacturing an active matrix liquid crystal display device of the present invention, a liquid crystal is sandwiched between a pair of substrates, and a plurality of substrates are provided on at least one of the pair of substrates. In the method for manufacturing an active matrix type liquid crystal display device having a signal line, a MIM nonlinear resistance element connected to the signal line, and a pixel electrode connected to the MIM nonlinear resistance element, an underlayer is formed on the one substrate. A first step of forming an insulating film; and an etching rate increasing in a film forming direction on the base insulating film.
A second step of forming two or more layers by controlling the film quality so as to form a gradient film, and wet etching the film formed in the second step with an etchant containing hydrofluoric acid and nitric acid to form a lower electrode. a third step of patterning so, a fourth step of forming an anodic oxidation device insulating layer of the lower electrode, and a fifth step of forming a conductive film on the device insulating layer, the conductive And forming a MIM element by etching and patterning the conductive film to become an upper electrode.

According to another method of manufacturing an active matrix liquid crystal display device of the present invention, a liquid crystal is sandwiched between a pair of substrates, and a plurality of signals provided on at least one of the pair of substrates. A method of manufacturing an active matrix liquid crystal display device having a line, a MIM nonlinear resistance element connected to the signal line, and a pixel electrode connected to the MIM nonlinear resistance element, wherein a base insulating film is formed on the one substrate. A first step of forming a film, and a gradient in which an etching rate is increased in a film forming direction on the base insulating film.
A second step of forming two or more layers of films by controlling the film quality to form a film, and wet etching the film formed in the second step with an etchant containing hydrofluoric acid and nitric acid to form a lower electrode. A fourth step of anodizing the lower electrode to form a barrier insulating film, and a fifth step of etching and removing a part of the barrier insulating film with an etchant containing hydrofluoric acid and hydrochloric acid. and step, a seventh step of forming a sixth step of forming a part that is etched away again anodized element insulating film, a conductive film to the sixth step of the element insulating film, the conductive Eighth to form an MIM element by etching and patterning the conductive film to become the upper electrode
And a step of:

According to still another method of manufacturing an active matrix type liquid crystal display device of the present invention, a liquid crystal is sandwiched between a pair of substrates, and a plurality of substrates are provided on at least one of the pair of substrates. In a method for manufacturing an active matrix liquid crystal display device having a signal line, a MIM nonlinear resistance element connected to the signal line, and a pixel electrode connected to the MIM nonlinear resistance element, a base insulating layer may be formed on the one substrate. A first step of forming a film, and an etching rate increases in a film forming direction on the base insulating film.
A second step in which two or more layers are formed by controlling the film quality so as to form a gradient film, and the film formed in the second step is wet-etched with an etchant containing hydrofluoric acid and nitric acid to form a lower electrode A third step of patterning as described above, a fourth step of forming an element insulating film by anodizing the lower electrode,
A fifth step of forming a conductive film on the device insulating layer of the fourth step, a sixth step of forming an etch patterning MIM element such that the upper electrode the conductive film, the device A seventh step of etching and removing a part of the insulating film with an etchant containing hydrofluoric acid and hydrochloric acid, and an eighth step of etching and separating the removed portion of the element insulating film again with an etchant containing hydrofluoric acid and nitric acid. It is characterized by having.

[0014]

[0015]

(Example 1) A first manufacturing process of an MIM element substrate according to the present invention will be described with reference to FIG.
Will be explained . 1 (a) is a flowchart showing the processing steps, (g) from FIG. 1 (b) shows a cross-sectional view of the MIM element corresponding to the flowcharts. TaO _X was sputtered on the Ba borosilicate glass substrate 1 at 500 Å to form a base insulating film 2. As a sputtering apparatus, 50B manufactured by Tokuda Seisakusho was used , and a DC film was formed of Ta in a mixed sputtering gas of Ar-15% N ₂ and O ₂ . The partial pressure of each of the sputtering gases was 0.3 Pa. After the formation of the base insulating film, the O ₂ partial pressure was gradually reduced to 0 without stopping the sputter plasma. At this time, Ar-15% N ₂ was introduced in an amount corresponding to the reduced O ₂ partial pressure, and the total gas pressure became 0.1%.
It was kept at 6 Pa. Ar-15% N ₂ gas flow rate at this time was 20 SCCM, and a 2000 Å deposited view 1 (c) 3-1 in this condition. Without stopping the sputter plasma again, keeping the gas pressure at 0.6 Pa, while controlling the orifice, the Ar-15% N ₂ flow rate was increased to 60 SC.
Increased to CM. Under these conditions, 1000 angstroms were laminated to form FIG. 1 (c) 3-2. Next, Tokyo Oka's OF
PR800 was coated at 1.4 microns, baked at 90 degrees Celsius for 20 minutes, and exposed and developed to obtain a predetermined resist pattern. After post-baking at 120 degrees Celsius for 30 minutes, hydrofluoric acid, nitric acid and water having a concentration of 40% were mixed at a volume ratio of 1: 8: 5 degrees Celsius 2.
It was immersed in a 0 degree etchant, and the N-Ta film was etched and patterned to form lower electrodes 3 (3-1, 3-2).
The etching time was 1 minute and there was no peeling of the resist. Next, the resist was peeled off using ST-10 manufactured by Tokyo Ohka.
Anodization was performed in a 1% aqueous citric acid solution to form a 600 Å element insulating film 4 (4-1, 4-2).
The anodizing voltage was 33V. Then, I made of Anelva
A 30 angstrom DC sputtered film of Cr was formed on the LC-705, and ITO was continuously formed without stopping the sputter plasma.
Was formed into a film having a thickness of 500 angstroms to obtain FIG.
A predetermined resist is formed again in the same manner as the patterning of the lower electrode, and the ITO film is etched with a mixed acid aqueous solution of nitric acid and hydrochloric acid. Subsequently, the Cr film under the ITO film is etched with a ceric ammonium nitrate aqueous solution. Form upper electrode 5
Then , the MIM element and the pixel electrode were simultaneously formed. The size of the MIM element was 4 microns * 4 microns.

Assembling the MIM element substrate and the counter substrate,
Lighting test after liquid crystal filling, MI of 30cm * 35cm
There was no defect in the M element substrate. The display contrast was 150: 1 or more at room temperature and 100: 1 or more at 50 degrees Celsius, which was good. The reason for the good contrast is as follows.

Region 4-2 occupying most of the element insulating film
Contains about 20 at% of N, which lowers the relative dielectric constant of the insulating film and the capacitance of the element.

Since the element insulating film 4 contains N, free Ta ions which are usually present in the Ta anodic oxide film are fixed to improve the leak current.

Since the lower electrode 3-1 contains N of 2 to 3 at%, it has an alpha-Ta structure with less distortion, and the specific resistance is lowered to 40 micro ohm cm. Thereby, the voltage applied to the MIM element does not become dull.

When the MIM display was disassembled and the MIM element substrate was observed, there was no reaction product or Ta residue caused by the chemical dry etching which had been a problem in the conventional chemical dry etching. Further, when the tapered shape of the lower electrode 3 was observed by SEM, as shown in FIG.
Was almost vertical, but 3-1 had a gentle taper of about 30 degrees. When the etching rate of the etchant (mixed acid of hydrofluoric acid and nitric acid) of this embodiment of 3-1 and 3-2 was examined, it was about 2: 1, and it was about 2: 1 when 3-1 was etched. 3-2 is etched in the direction parallel to the substrate at twice the speed, and 3-1
Is etched into a taper. That is, 3-
By controlling the etching rate ratio of 1 and 3-2, the etching taper angle of 3-1 can be arbitrarily controlled. When the N doping amount of the laminated film of the lower electrode was actually changed by changing the flow rate of the sputtering gas, the taper angle of 3-1 could be arbitrarily changed at 90 degrees or less. 3-2
Although there was no disconnection of the upper electrode at all even though it was almost vertical, its thickness was as small as 1000 angstroms and had little effect, so that the underlying insulating film was hardly etched and remained in the etchant of this embodiment. This is probably because the adhesion of the upper electrode was good.

( Comparative Example 1 ) This comparative example is different from Example 1 in that the multilayer film of the lower electrode of Example 1 was made into a single layer. After the formation of the base insulating film, the O ₂ partial pressure is gradually reduced without stopping the sputter plasma. Ar-15% N ₂ is introduced by the reduced O ₂ partial pressure, and the total gas pressure is 0.1%. It was kept at 6 Pa. At this time, the flow rate of the Ar-15% N ₂ gas was 60 SCCM, and a film of 3000 Å was formed under these conditions to obtain FIG. The subsequent steps are the same as in the first embodiment. Assembling this MIM element substrate and counter substrate, filling in liquid crystal, and performing a lighting test.
defect exists large number MIM device substrate of m. The display contrast was 150: 1 to 90: 1 at room temperature and 90: 1 to 50: 1 at 50 degrees Celsius. The contrast is inferior to that of Example 1 and the variation in the substrate surface is that the lower electrode contains about 20 at% of N-doped Ta, so that the specific resistance is as high as 220 μOhm cm and the voltage drop is caused by the voltage drop. It is considered that a voltage is not sufficiently applied to the MIM element. Further, when the MIM display body was disassembled and the MIM element substrate was observed, the reaction product and the Ta caused by the chemical product which had been a problem in the conventional chemical dry etching were observed.
There was no rest. Further, when the tapered shape of the lower electrode 3 was observed by SEM, it was almost vertical and had no inclination. For this reason, when forming the upper electrode, the film was not sufficiently formed on the etching tapered portion, which led to disconnection of the upper electrode, resulting in a defect during a lighting test. Therefore, it can be seen that simply eliminating dry etching does not improve the manufacturing yield.

(Comparative Example 2) This comparative example is different from Example 1 in that the multilayer film of the lower electrode of Example 1 was made into a single layer. After the formation of the base insulating film, the O ₂ partial pressure is gradually reduced without stopping the sputter plasma. Ar-15% N ₂ is introduced by the reduced O ₂ partial pressure, and the total gas pressure is 0.1%. It was kept at 6 Pa. At this time, the flow rate of the Ar-15% N ₂ gas was 20 SCCM, and 3000 angstrom film was formed under these conditions to obtain FIG. 1 (c) 3. The subsequent steps are the same as in the first embodiment. Assembling this MIM element substrate and counter substrate, filling in the liquid crystal and testing the lighting, 30cm * 35c
defect exists many in MIM element substrate meat m. The display contrast was 90: 1 at room temperature and 50: 1 at 50 degrees Celsius. The contrast was inferior to that of Example 1 because the element insulating film contained only about 2% of N, and although the leakage current was improved, the capacitance of the element was not sufficiently reduced. Also, the MIM display body is disassembled and the MIM
Observation of the element substrate revealed that there was no reaction product which had been a problem in the conventional chemical dry etching and no Ta residue caused by the reaction product . Further, when the tapered shape of the lower electrode 3 was observed by SEM, it was almost vertical and had no inclination. Therefore, when the upper electrode was formed, the film was not sufficiently formed on the etching tapered portion, which led to disconnection of the upper electrode, which was a defect in the relighting test. Therefore, it can be seen that simply eliminating dry etching does not improve the manufacturing yield.

[0023] (Example 2) This example forming the lower electrode in Example 1, Step A
In this method , Ta is reactively sputtered in an atmosphere containing r, N ₂ and O ₂ . After forming the base insulating film,
Without stopping the sputter plasma, the O ₂ partial pressure was gradually reduced to 0. Amount of this time reduced O ₂ partial pressure Ar-
15% N ₂ was introduced and the total gas pressure was kept at 0.6 Pa. At this time, the flow rate of the Ar-15% N ₂ gas is 20.
It was SCCM, and a film of 2000 angstrom was formed under these conditions to obtain 3-1 in FIG. While the gas pressure of 0.6Pa not stop again sputtering plasma, 0.55Pa to Ar-15% N ₂ partial pressure while controlling the orifice, the O ₂ partial pressure of 0.05 Pa, 3000 angstroms formed in this condition The film was formed as shown in FIG. At this time, Ar-1
5% N ₂ flow rate was 200 SCCM. The subsequent steps are the same as in the first embodiment. However, the width of the upper electrode was 20 microns.

Assembling the MIM element substrate and the opposing substrate,
Lighting test after liquid crystal filling, MI of 30cm * 35cm
There was no defect in the M element substrate. The display contrast was 200: 1 or more at room temperature and 180: 1 or more at 50 degrees Celsius, which was good. The reason for the good contrast is as follows.

In FIG. 1 (d) 3-2, since the insulating property is high, only the portion 4-1 of the element insulating film having a low resistance exists. Therefore, the manufacturing method is almost the same as that of the first embodiment, but the device capacitance is very small because of the lateral MIM device structure, and the leak current is also improved because the device area is small.

Since the element insulating film 4-1 contains N, free Ta which is usually present in the Ta anodic oxide film is used.
The ions were fixed and the leakage current was further improved.

Since the lower electrode 3-1 contains 2 to 3 at% of N, the lower electrode 3-1 has an alpha-Ta structure with less distortion, and the specific resistance is reduced to 40 micro ohm cm. Thereby, the voltage applied to the MIM element does not become dull.

When the MIM display was disassembled and the MIM element substrate was observed, there was no reaction product or Ta residue caused by the chemical dry etching which had been a problem in the conventional chemical dry etching. Further, when the tapered shape of the lower electrode 3 was observed by SEM, as shown in FIG.
Was almost vertical, but 3-1 had a gentle taper of about 40 degrees. The reason is the same as in the first embodiment.

[0029] (Embodiment 3) This embodiment of Oite lower electrode 3-2 to Example 1 SiO _X N
_It is changed to _Y. After the formation of the base insulating film, the O ₂ partial pressure was gradually reduced to 0 without stopping the sputter plasma. At this time, Ar-15% N ₂ was introduced by the reduced O ₂ partial pressure, and the total gas pressure was kept at 0.6 Pa.
At this time, the flow rate of the Ar-15% N ₂ gas was 20 SCMMM, and under this condition, a 2000 Å N-Ta film was formed to obtain the structure shown in FIG. Here, the sputtering plasma is stopped once, the gas pressure is kept at 0.6 Pa, and while controlling the orifice, the Ar-15% N ₂ partial pressure is set to 0.3 Pa and the O ₂ partial pressure is set to 0.3 Pa, and then the sputtering of Si is started. I do. Under these conditions, a 3000 Å film was formed and FIG.
(C) 3-2. At this time, the flow rate of Ar-15% N ₂ is 1
00 SCCM. The subsequent steps are the same as in the first embodiment. However, the width of the upper electrode was 20 microns.

Assembling the MIM element substrate and the opposing substrate,
Lighting test after liquid crystal filling, MI of 30cm * 35cm
There was no defect in the M element substrate. The display contrast was 200: 1 or more at room temperature and 180: 1 or more at 50 degrees Celsius, which was good. The reason for good contrast is Example 4.
Is the same as

Further, when the MIM display was disassembled and the MIM element substrate was observed, the reaction product and the Ta caused by the reaction which had been a problem in the conventional chemical dry etching were observed.
There was no rest. Further, when the tapered shape of the lower electrode 3 was observed by SEM, as shown in FIG.
2 was almost vertical, but 3-1 had a gentle taper of about 40 degrees. The reason is the same as in the first embodiment.

The sputtering gas at the time of film formation in 3-2 is Ar-1
By using 5% N ₂ or Ar—O ₂ , the film of 3-2
iN _x or SiO _x can also be used. The effect at that time does not change.

(Embodiment 4 ) A fourth embodiment of the present invention will be described with reference to FIG. After the formation of the base edge film, the O ₂ partial pressure was gradually reduced to 0 without stopping the sputter plasma. At this time, Ar-15% N ₂ was introduced in an amount corresponding to the reduced O ₂ partial pressure, and the total gas pressure became 0.1%.
It was kept at 6 Pa. At this time, the flow rate of the Ar-15% N ₂ gas was 20 SCCM, and under this condition, a film of 4000 Å was formed to obtain 3-1 in FIG. Without stopping the sputter plasma again, keeping the gas pressure at 0.6 Pa, while controlling the orifice, the Ar-15% N ₂ flow rate was increased to 60 SCC.
M. Under these conditions, 1000 angstroms were laminated to form 3-2 in FIG. Next, Tokyo Oka's OFP
R800 was coated at 1.4 microns, baked at 90 degrees Celsius for 20 minutes , and exposed and developed to obtain a predetermined resist pattern. After post-baking at 120 degrees Celsius for 30 minutes, hydrofluoric acid, nitric acid and water having a concentration of 40% were mixed at a volume ratio of 1: 8: 5 degrees Celsius 2.
It was immersed in a 0 degree etchant, and the N-Ta film was etched and patterned to form lower electrodes 3 (3-1, 3-2).
The etching time was 1 minute, and there was no peeling of the resist. Next, the resist was peeled off using ST-10 manufactured by Tokyo Ohka.
Anodizing was performed in a 1% aqueous citric acid solution to form a 2000 Å barrier insulating film 6. The anodizing voltage was 110V. A predetermined resist pattern is formed again on the barrier insulating film, immersed in an etchant of 20 degrees Celsius in which hydrofluoric acid, hydrochloric acid and water of the above concentrations are mixed at a ratio of 1: 8: 3, and barrier insulation of only the tapered portion is performed. The film was etched away (f). The etching time was 1 minute, the resist was not stripped, and the lower electrode N-Ta film was hardly etched. Next, the resist is stripped off using ST-10 manufactured by Tokyo Ohka, and anodized in a 0.1% citric acid aqueous solution.
An element insulating film 4 of 0 Å was formed (g).
The anodizing voltage was 33V. Then, I made of Anelva
A 30 angstrom DC sputter film is formed on the LC-705 and the ITO film is continuously formed without stopping the sputter plasma.
Was formed into a film having a thickness of 500 Å, as shown in FIG.
A predetermined resist is formed again in the same manner as the patterning of the lower electrode, and the ITO film is etched with an aqueous solution of a mixed acid of nitric acid and hydrochloric acid. Forming electrodes 5;
An MIM element and a pixel electrode were simultaneously formed (i). MIM
The size of the device was 4 microns for the lower electrode * 20 microns for the upper electrode.

Assembling the MIM element substrate and the counter substrate,
Lighting test after liquid crystal filling, MI of 30cm * 35cm
There was no defect in the M element substrate. The display contrast was 200: 1 or more at room temperature and 180: 1 or more at 50 degrees Celsius, which was good. The reason for good contrast is Example 5.
Is the same as Further, when the tapered shape of the lower electrode 3 was observed by SEM, as shown in FIG. 2D, 3-2 was almost vertical, but 3-1 had a gentle taper of about 30 degrees. The reason is the same as in the first embodiment.

(Embodiment 5 ) The serial MIM element is a BACK TO BACK MI
Also called an M element, two MIM elements are connected in series and arranged. For this reason, the oxidized Ta film must be formed in an island shape. After forming the lower electrode anodized in the same manner as in Example 1 (however, the anodic oxidation voltage was set to 20 V),
A resist pattern for separating into islands was formed, and the resist pattern was immersed in an etchant of 20 degrees Celsius in which hydrofluoric acid, hydrochloric acid and water were mixed at a ratio of 1: 8: 3, and only a part of the anodic oxide film was removed by etching. The etching time was about 40 seconds, the resist was not stripped, and the lower electrode N-Ta film was hardly etched. Next, the resist is immersed in a 20% Celsius etchant in which 40% hydrofluoric acid, nitric acid and water are mixed at a volume ratio of 1: 8: 5, and the N-Ta under the removed anodic oxide film is removed. The film was removed by etching to form anodically oxidized island-shaped N-Ta. The etching time was about 1 minute, and there was no peeling of the resist. Then, I made of Anelva
A 30 angstrom DC sputtered film of Cr was formed on the LC-705, and ITO was continuously formed without stopping the sputter plasma.
Was formed to a thickness of 500 Å. Again, a signal electrode for applying a voltage to the MIM element and a resist so as to connect the island pattern and the pixel are formed in the same manner as the patterning of the lower electrode, and a resist is formed so as to connect the island pattern to the pixel. Then, the Cr film under the ITO film was etched with an aqueous ceric ammonium nitrate solution. That _{ITO-Cr- <TaO X N Y} - (N-
Ta) -TaO _X N _Y> - has a structure of [Cr-ITO]. The portion indicated by <> is the above-mentioned island pattern.
[] Is a pixel electrode. The size of the MIM element was 4 microns for the lower electrode and 4 microns for the upper electrode.

Assembling the MIM element substrate and the opposing substrate,
Lighting test after liquid crystal filling, MI of 30cm * 35cm
There was no defect in the M element substrate. The display contrast was 150: 1 or more at room temperature and 100: 1 or more at 50 degrees Celsius, which was good. The reason for good contrast is Example 1.
Is the same as Further, since there is no polarity difference between the IV characteristics of the MIM element, the afterimage of the display is improved.

[0037] (Example 6) Example 1, but 2, 3, 4 and 5 were using a multilayer film in the lower electrode, formed in Example 1, the sputtering gas composition in 2,4,5 lower electrode changing continuously from start to finish,
Voltage applied to the Ta and Si targets in Example 3 ,
In addition, by continuously changing the composition of the sputtering gas, the composition of the lower electrode can be continuously changed, and a gradient film having a continuously increased etching rate in the film forming direction can be obtained. For example, in Example 1, after the formation of the base insulating film, the O ₂ partial pressure was gradually reduced to 0 without stopping the sputter plasma. At this time, Ar-1 is reduced by the reduced O ₂ partial pressure.
5% N ₂ was introduced and the total gas pressure was kept at 0.6 Pa. At this time, the flow rate of the Ar-15% N ₂ gas is 20S.
CCM. The gas pressure is kept at 0.6 Pa without stopping the sputter plasma again, while controlling the orifice.
r-15% N ₂ flow rate is gradually increased to 60SCCM and
When the lower electrode is laminated at 3000 Å, Ar-
15% N ₂ flow rate was set to 60 SCCM. The subsequent steps are the same as in the first embodiment. In this case, the quality of the display does not change, but the taper state of the lower electrode is different. That is, in the case of the laminated film, the tapered portion is 3-1. However, in the case of the inclined film, the entire lower electrode is uniformly tapered, and the manufacturing margin is increased.

[0038]

According to the present invention, a chemical dry etch which has a problem of re-deposition in an N-doped MIM, a lateral MIM, or a serial MIM can be completely converted to a taper control wet type etch, thereby greatly improving the production yield. effective. In addition, the etching throughput is 10 times or more as compared with the dry process, and the manufacturing cost can be reduced since the apparatus is extremely inexpensive. Further, a lateral MIM element, which conventionally requires a process similar to that of a TFT element, can be manufactured with two photomasks. As described above, a display having image quality comparable to that of a TFT can be manufactured at a much lower cost than a conventional MIM element.

[Brief description of the drawings]

FIG. 1 is a basic manufacturing process diagram of MIM elements of Examples 1, 4, and 5 of the present invention.

FIG. 2 is a basic manufacturing process diagram of an MIM element according to Embodiment 6 of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Base insulating film 3 Lower electrode 4 Element insulating film 5 Upper electrode 6 Barrier insulating film

Continuation of the front page (56) References JP-A-63-72126 (JP, A) JP-A-64-5217 (JP, A) JP-A-63-236365 (JP, A) JP-A-3-53084 (JP, A) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G02F 1/1362 H01L 49/02

Claims (6)

(57) [Claims] A liquid crystal is sandwiched between a pair of substrates,
An active matrix type including a plurality of signal lines provided on at least one of the pair of substrates, a MIM nonlinear resistor connected to the signal line, and a pixel electrode connected to the MIM nonlinear resistor. In the method for manufacturing a liquid crystal display device, a first step of forming a base insulating film on the one substrate; and a step of forming a large etching rate on the base insulating film in a film forming direction.
A second step of laminating and forming two or more layers by controlling the film quality so as to form a graded film, and wet etching the film formed in the second step with an etchant containing hydrofluoric acid and nitric acid. and a third step of patterning so, a fourth step of forming an anodic oxidation device insulating layer of the lower electrode, and a fifth step of forming a conductive film on the element insulating film, and the A sixth step of forming an MIM element by etching and patterning the conductive film to be an upper electrode to form an MIM element. 2. A liquid crystal is sandwiched between a pair of substrates,
An active matrix type including a plurality of signal lines provided on at least one of the pair of substrates, a MIM nonlinear resistor connected to the signal line, and a pixel electrode connected to the MIM nonlinear resistor. In the method for manufacturing a liquid crystal display device, a first step of forming a base insulating film on the one substrate; and a step of forming a large etching rate on the base insulating film in a film forming direction.
A second step of laminating and forming two or more layers by controlling the film quality so as to form a graded film, and wet etching the film formed in the second step with an etchant containing hydrofluoric acid and nitric acid. A fourth step of anodizing the lower electrode to form a barrier insulating film; and removing a part of the barrier insulating film by etching with an etchant containing hydrofluoric acid and hydrochloric acid. a fifth step of, a seventh step of forming a sixth step of forming a part that is etched away again anodized element insulating film, a conductive film to the sixth step of the element insulating film An eighth step of forming an MIM element by etching and patterning the conductive film so as to be an upper electrode. 3. A liquid crystal is sandwiched between a pair of substrates,
An active matrix type including a plurality of signal lines provided on at least one of the pair of substrates, a MIM nonlinear resistor connected to the signal line, and a pixel electrode connected to the MIM nonlinear resistor. In the method for manufacturing a liquid crystal display device, a first step of forming a base insulating film on the one substrate; and a step of forming a large etching rate on the base insulating film in a film forming direction.
A second step of laminating and forming two or more layers by controlling the film quality so as to form a graded film, and wet etching the film formed in the second step with an etchant containing hydrofluoric acid and nitric acid. a third step of patterning such that, fifth forming the fourth step and a conductive film on said fourth step of the element insulating film forming the lower electrode by anodizing device insulating layer A sixth step of forming an MIM element by etching and patterning the conductive film to be an upper electrode; and a seventh step of etching and removing a part of the element insulating film with an etchant containing hydrofluoric acid and hydrochloric acid. And an eighth step of again separating the removed portion of the element insulating film by etching with an etchant containing hydrofluoric acid and nitric acid. 4. A laminated film and an inclined film having an increased etching rate in a film forming direction in the second step are obtained by reactive sputtering of Ta in an atmosphere containing Ar and N _2. method for manufacturing an active matrix type liquid crystal display device according to any one of claims 1 to 3. 5. A laminated film and an inclined film having an increased etching rate in a film forming direction in the second step are formed of Ar, N ₂ ,
And preparation of an active matrix type liquid crystal display device according to any one of claims 1乃<br/> optimum 3, characterized in that it is obtained by reactive sputtering of Ta in an atmosphere containing Ar and N ₂ and O ₂ Method. Wherein said second multilayer film and the inclined film deposition direction increases the etching rate of the process, Ta in an atmosphere containing atmosphere or Ar and N ₂ and O ₂ containing Ar and N ₂ the after reactive sputtering and reactive sputtering, SiO _x, SiN _x or SiO _x N _y the claims 1 to 3 active matrix type liquid crystal according to any one characterized in that it is obtained laminated film was <br/> A method for manufacturing a display device.