KR20110025378A - Composition for etching metal layer - Google Patents

Abstract

PURPOSE: A composition for etching a metal layer is provided to ensure excellent over etch rate and inclined angle of the etched metal layer, and to obtain excellent etching profile in case that the film thickness of a metal layer is changed. CONSTITUTION: A composition for etching a metal layer includes 50~65 weight% of phosphoric acid, 1~10 weight% of nitric acid, 10~25 weight% of acetic acid, 0.01~5 weight% of etching adjustor, and the balance of water. The etching adjustor is inorganic nitrate-based compounds or sulfuric acids. The inorganic nitrate-based compounds are selected from the group consisting of NH4NO3, Zn(NO3)2, Co(NO3)2, Ni(NO3)2, Fe(NO3)3, Cu(NO3)2 and AgNO3.

Description

Metal film etching composition {COMPOSITION FOR ETCHING METAL LAYER}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an etching composition for etching a single layer or multilayer metal film, and more particularly, to an etching composition capable of collectively etching a single film or a multilayer film of metal for forming an electrode of a flat panel display device.

In general, a flat panel display device has a thin film transistor formed on a glass substrate, and the thin film transistor is electrically connected through various metal wires. The manufacturing process of such metal wirings typically includes a metal thin film forming process using an adsorption method, a pattern forming process by exposing a photoresist, and an etching process. Here, the etching process is a process of selectively leaving a metal thin film based on the pattern formed by the exposure process, in which an etching composition is used.

As metal wiring materials of thin film transistors, aluminum or aluminum alloys are generally used. However, pure aluminum is weak in chemical resistance and causes defects due to the hillock phenomenon of aluminum during the process after etching. Typically, metals such as molybdenum, chromium, titanium, and tungsten are deposited on top of aluminum or an aluminum alloy. The multilayered film structure is applied.

As a composition for etching for etching the metal film of such a multilayer film structure, the composition which has phosphoric acid as a main component is known. However, when wet etching is performed using such an etching composition mainly containing phosphoric acid, poor etching profiles are often obtained due to the difference in etching rates between the lower aluminum film and the other metal film on the upper surface.

For example, in the case of a double film in which molybdenum is deposited on an aluminum-neodymium alloy film, the etching rate of the aluminum alloy is faster than that of molybdenum, so that the upper molybdenum film remains more than the lower aluminum alloy film. This increases the likelihood that a short circuit, disconnection, etc. of the thin film will occur during the subsequent thin film process, which causes a decrease in yield.

In order to solve this problem, Korean Patent Publication No. 2004-0017078 proposed a method of secondly etching a molybdenum film protruding outward from an aluminum film after etching. However, this method requires a separate secondary etching, which is disadvantageous in productivity or process operation.

BACKGROUND ART A composition comprising phosphoric acid, nitric acid, acetic acid, and water is known as an etching composition for wet etching a single film or a multilayer film made of aluminum or aluminum alloy and molybdenum. For effective multilayer etching, the etching rate must be kept uniform by reducing the difference in etching speed between metal multilayers, the etching uniformity by pattern must be secured, and the inclination angle of the etched thin film must be solved. In order to improve this problem, a method of adding an additive to phosphoric acid, nitric acid, acetic acid and water has been attempted.

For example, in Korean Patent Publication Nos. 2002-0078583, 2004-0080963, and 2006-0033689, perchloric acid and perchlorate are further used as additives to adjust the oxidation rate. However, in the case of perchloric acid and its salts, attention should be paid to the use of environmentally regulated materials, and there is a disadvantage in that the cost of waste etching treatment is high.

Meanwhile, Korean Patent Publication Nos. 2007-0060684 and 2008-0004894 propose a batch wet etching solution using a halogen-based additive when etching aluminum, molybdenum or their alloys and ITO. In this case, hydrofluoric acid, bromic acid, or salts thereof are used as the halogen-based additives, and these halogen-based additives cause etching problems of the glass substrate and require caution in use because these components are harmful to the human body.

In addition, Korean Patent Publication No. 2004-0014184, 2004-0088108 proposes an etching composition comprising a compound containing a hydroxy functional group as phosphoric acid, nitric acid, acetic acid and additives. However, in the case of such an etching composition, due to the reaction between nitric acid and the additive, the hydroxyl functional group may be decomposed to cause a problem in stability.

Most aluminum-molybdenum batch etch compositions have made great efforts to slow down the molybdenum monolayer etch rate, and the bias adjustment is caused by the variation of the over-etch ratio, and the inclination angle increases rapidly as the over-etch ratio increases. CD (critical dimension) bias adjustment is necessary. Therefore, the process is complicated and the efficiency of the process operation is reduced. In addition, as the use of large-area substrates and the process of simplifying the process (less mask process), the importance of securing the etching uniformity and preventing the photoresist from breaking is emerging. Therefore, the development of an etching composition that meets these requirements has been developed. Required.

Accordingly, the present invention is to provide an etching composition capable of etching the metal film efficiently and stably.

In addition, the present invention is to provide a composition for batch etching that can obtain an excellent etching profile as a result of the metal film etching, and can maintain the uniformity of the etching, in particular, even if the multi-layered metal film in a batch at the same time excellent etching profile and etching It provides an etching composition that can ensure the uniformity.

The present invention shows an excellent etching profile in etching single or multilayer films including aluminum, aluminum alloy and molybdenum, which are used as metal electrodes of thin film transistors, especially for flat panel displays, ensuring uniformity of etching and damaging photoresist. It is to provide a composition for batch etching without this.

In addition, it solves problems such as the use of environmental regulatory substances or harmful substances, the stability of additives, and the like, which are a problem in the conventional etching solution of the present invention, and solves the problem of increasing the inclination angle according to the over-etching ratio, thereby ensuring stable and robust etching even on the change of thin film thickness. It is for providing a composition for.

In order to achieve the above object, the present invention provides a metal film etching composition further comprising an etch regulator in addition to phosphoric acid, nitric acid, acetic acid and water. The metal film etching composition according to the present invention may further include an etching inhibitor.

Specifically, the present invention is a metal film etching composition comprising 50 to 65% by weight of phosphoric acid, 1 to 10% by weight of nitric acid, 10 to 25% by weight of acetic acid, 0.01 to 5% by weight of an etchant and a residual amount of water. To provide.

Here, the etch regulator serves to prevent the occurrence of local battery phenomena by adjusting the redox potential of the metal, and to obtain an equal etching rate between the metal films, particularly in a metal multilayer structure. As such an etching regulator, an inorganic nitrate compound or sulfuric acid can be used. Examples of the inorganic nitrate compounds include NH ₄ NO ₃ , Zn (NO ₃ ) ₂ , Co (NO ₃ ) ₂ , Ni (NO ₃ ) ₂ , Fe (NO ₃ ) ₃ , Cu (NO ₃ ) _2, and AgNO ₃ Etc. That is, as the inorganic nitrate compound, NH ₄ NO ₃ , Zn (NO ₃ ) ₂ , Co (NO ₃ ) ₂ , Ni (NO ₃ ) ₂ , Fe (NO ₃ ) ₃ , Cu (NO ₃ ) ₂ and AgNO ₃ One selected from the group consisting of can be used.

Such etch modifiers may use commercially available products. Those skilled in the art will be able to make or purchase the etch control agents described above in a timely manner.

The metal film etching composition according to the present invention may further comprise an etching inhibitor by 0.01 to 5% by weight based on the total weight of the composition.

In the present invention, as an etching inhibitor, glycine, alanine, valine, valine, leucine, metopnine, isolenecine, phenylalanine, phenylalanine, tyrosine, tyrosine, etc. Tryptophan, Serine, Threonine, Cysteine, Proline, Asparagine, Glutamine, Lysine, Arginine, Histidine Histidine), aspartate (Aspartate) and glutamate (Glutamate) selected from the group consisting of amino acid compounds can be used.

As such an etch inhibitor, a commercially available product can be used. Those skilled in the art will be able to make or purchase the etch inhibitors described above as appropriate.

The metal film etching composition according to the present invention may be used for etching a single film or a multilayer film made of an aluminum film, an aluminum alloy film, and a molybdenum film.

That is, the metal film to which the composition for etching a metal film according to the present invention may be applied may be a single film selected from the group consisting of an aluminum film, an aluminum alloy film, and a molybdenum film, or a multilayer film in which the single film is laminated two or more times. have.

Specifically, the metal film etching composition according to the present invention may be applied to etching a single film made of aluminum, a single film made of aluminum alloy, or a single film made of molybdenum. As the double film, for example, the metal film etching composition according to the present invention can also be applied to etching a double film made of aluminum and molybdenum, and a double film made of aluminum alloy and molybdenum. Furthermore, the metal film etching composition according to the present invention may be applied to the etching of the triple layer of molybdenum / aluminum / molybdenum, the molybdenum / aluminum alloy / molybdenum as well as triple or more laminations of other combinations. It can be applied to etching the multilayer film.

According to an example of the present invention, the aluminum alloy may be an alloy of aluminum and neodymium (Al-Nd).

Those skilled in the art will be able to appropriately prepare the aluminum, aluminum alloy and molybdenum described above. According to one embodiment of the present invention, in the case of an aluminum alloy, an aluminum alloy that has been conventionally used for manufacturing a metal film for wiring of a display device may be selected and used appropriately, and according to another example of the present invention, an alloy of aluminum and neodymium (Al-Nd ) Can also be obtained and used in the manufacture of metal films for wiring of conventional display devices.

According to an example of the present invention, the metal film may include at least one molybdenum film, and the etching inhibitor may apply a molybdenum etching inhibitor. As the molybdenum inhibitor, the glycine (Glycine), alanine (Alanine), valine (Valine), leucine (Leucine), metopinine (Methopnine), isolenecine (Phenylalanine), tyrosine (Tyrosine), tryptophan (Tyrosine) Tryptophan, Serine, Threonine, Cysteine, Proline, Asparagine, Glutamine, Lysine, Arginine, Histidine, Aspartate An amino acid compound selected from the group consisting of Aspartate and Glutamate can be used.

According to one embodiment of the present invention, the metal film is for forming a metal electrode pattern of the thin film transistor for flat panel display, the metal film etching composition according to the present invention can be usefully applied to the metal electrode pattern for forming a thin film transistor for flat panel display. have.

Here, the metal electrode is not limited in kind. According to an example of the present invention, the metal electrode may be, for example, a gate electrode or a data electrode.

The flat panel display to which the metal film etching composition of the present invention can be applied can be applied to any type of flat panel display device without limitation, and can be particularly useful for a liquid crystal display device.

According to an example of the present invention, the metal film etching composition may further include an etching regulator and a molybdenum etching inhibitor in the etching composition including phosphoric acid, nitric acid, acetic acid and water to show excellent etching characteristics and process operating margins. have.

In order to obtain a uniform etching rate between metals in a multilayer film made of a metal selected from aluminum, aluminum alloy, and molybdenum, mainly alkali salts or alkaline earth metal salts have been used as additives. When the alkali salts or alkaline earth metal salts are used, they provide electrons to both aluminum or aluminum alloys and molybdenum to match the etching rate. However, this method is difficult to uniformly adjust the etching rate when the thickness of the lower aluminum or aluminum alloy film and the upper molybdenum film is changed. As a result, protrusion of the upper molybdenum occurs when the film thickness changes, and even when there is a slight process variation in the thin film deposition process, defects may occur in the wet etching.

In the present invention, by using a compound having a less ionization tendency as compared to the conventional etching composition as an etching regulator, in the multilayer film made of a metal selected from aluminum, aluminum alloy and molybdenum, the movement direction of electrons is reversed compared to the conventional etching composition. It was made. As a result, even when the film thickness is changed, the electron transfer in the aluminum, aluminum alloy or molybdenum layer is moved toward the etching solution to obtain a robust and good etching profile.

In the present invention, the molybdenum etching inhibitor is used to adjust the etching rate of the molybdenum monolayer so that etching can be performed in a desired pattern.

In general, when the molybdenum monolayer is etched with an etching composition including phosphoric acid, nitric acid, and acetic acid, the etching rate is too fast, and in many cases, it is impossible to control the etching time in the actual wet etching equipment. Various etching failures occur when the etching time is not controlled. Therefore, slowing down the etching rate of the molybdenum monolayer is an important factor in the batch etching solution.

Representative examples of such molybdenum etch inhibitors include nonpolar aliphatic amino acids (Glycine, Alanine, Valine, Leucine, Methopnine, Isolencine) and nonpolar aromatic amino acids (Phenylalanine, Tyrosine, Tryptophan), and polar amino acids (Serine, Threonine, Cysteine, Proline, Asparagine, Glutamine , Lysine, Arginine, Histidine, Aspartate, Glutamate).

When the metal film is etched using the etching composition according to the present invention, an excellent etching profile can be obtained, uniformity of etching is ensured, and there is no damage to the photoresist. In addition, the etching composition according to the present invention can be said that there is no dependence on the equipment, and does not use environmental regulation material, does not cost environmental treatment, and also secures a low inclination angle in comparison with the conventional etching composition in the subsequent process It is effective to lower the defective rate.

In addition, when the molybdenum film is etched using the etching composition according to the present invention, the inclination angle is not largely changed according to the over-etch ratio of the molybdenum single layer, thereby increasing the choice of equipment operation and CD bias adjustment.

In addition, when etching a multilayer film made of a metal selected from aluminum, aluminum alloy, and molybdenum, even if there is a change in the thickness of the upper molybdenum, there is no protrusion of molybdenum and a good etching profile can be obtained. Etch profiles can be obtained.

Hereinafter, the present invention will be described in more detail with reference to the following examples.

Example 1

Molybdenum monolayer (Mo); Aluminum-neodymium alloy / molybdenum double membrane (Al-Nd / Mo); Aluminum / molybdenum double membrane (Al / Mo); After forming an electrode pattern on each metal film formed of molybdenum / aluminum-neodymium / molybdenum triple layer (Mo / Al-Nd / Mo), etching was performed using the etching composition proposed in the present invention.

Examples of an etching composition including phosphoric acid, nitric acid, acetic acid, and an etchant, Cu (NO ₃ ) ₂ and water, are shown in Table 1, and phosphoric acid, nitric acid, acetic acid, and an etchant, Cu (NO ₃ ) ₂ , Examples of the etching composition comprising an etching inhibitor glycine (Glycine) and water are shown in Tables 2 and 3.

After preparing the composition for etching in accordance with the composition ratio of the following table, the prepared substrate is put into a spray wet etching experiment equipment (manufactured by KCTECH, model name: ETCHER (TFT)) and heated to maintain a temperature 40 ㅁ 0.5 ℃. When the etching process was performed using the prepared composition for etching. The over etch rate was etched by applying 30% and 100% of each film based on EPD (End Point Detection) of the pad part.

When the etching is completed, after washing with ultrapure water and dried using a drying apparatus, after removing the photoresist using a photoresist stripper, an electron scanning microscope (SEM; manufactured by Phillips, model name: NOVA-200) The etch profile was used to evaluate the inclination angle, unilateral CD loss, etch residue, and the like.

Table 1 below shows the results of etching using the conventional batch etching composition (comparatively 1 and 2) and the etching composition of the present invention (Examples 1 to 6).

division Board Composition (% by weight)
(Phosphate / nitric acid / acetic acid / Cu (NO ₃ ) ₂ / water) Tilt angle
(˚) One side
CD loss (㎛) Mo
protrusion
(Μm) O / E
ratio
(%) Residue
Whether Remarks Example 1 Al-Nd / Mo 57.0 / 4.4 / 19.2 / 1.0 / 18.4 68.4 0.27 0.0 30 × Good Example 2 57.0 / 4.4 / 19.2 / 2.0 / 17.4 63.4 0.14 0.0 30 × Good Example 3 57.0 / 2.5 / 15.0 / 2.0 / 23.5 61.8 0.14 0.0 30 × Good Example 4 Mo 57.0 / 4.4 / 19.2 / 1.0 / 18.4 77.4 0.35 - 30 × Good Example 5 57.0 / 4.4 / 19.2 / 2.0 / 17.4 75.8 0.23 - 30 × Good Example 6 57.0 / 2.5 / 15.0 / 2.0 / 23.5 66.6 0.21 - 30 × Good Comparative Example 1 Al-Nd / Mo 55.0 / 2.1 / 25.0 / 0.0 / 13.4 /
Additive 4.5 83.5 0.34 0.1 30 × Inadequate Comparative Example 2 Mo 55.0 / 2.1 / 25.0 / 0.0 / 13.4 /
Additive 4.5 81.9 0.45 - 30 × Good

In Comparative Examples 1 and 2, the additive is perchloric acid (HClO ₄ ), which is used as an additive in a conventional conventional batch etching composition.

In Table 1, when etching using a conventional etching composition (Comparative Example 1) in the case of double-layer etching, the molybdenum protrusion phenomenon was observed, but using the etching composition (Examples 1 to 3) according to the present invention In the case of etching, molybdenum protrusion was not observed, and the inclination angle was also 5 ° or more lower than that of the conventional etching composition, and it was confirmed that the inclination angle was 70 ° or less.

1 is a photograph obtained by etching a double layer using the etching composition prepared in Comparative Example 1 which is a conventional etching composition, Figure 2 is an etching obtained by etching the double layer using the etching solution obtained in Example 1 of the present invention. Profile.

Even in the case of molybdenum single layer etching, when using the etching composition according to the present invention as compared to the conventional etching composition (Comparative Example 2) (Examples 4 to 6), the inclination angle is lowered so that the step of smooth inclination is reduced. Seemed. As a result, it is expected that there will be no defects on subsequent film deposition.

Table 2 below shows the etching results of Examples 7 to 18 that etch various kinds of single, double and triple layers by using an etching composition further comprising glycine as an etching inhibitor.

division Board Composition (% by weight)
(Phosphate / nitric acid / acetic acid / Cu (NO ₃ ) ₂ / Glycine / water) Tilt angle
(˚) Unilateral CD loss
(Μm) Mo
protrusion
(Μm) O / E
ratio
(%) Residue
Whether Remarks Example 7 Al-Nd /
Mo 60.0 / 3.7 / 22.0 / 0.1 / 1.1 / 13.1 64.5 0.25 0.0 30 × Great Example 8 59.0 / 4.8 / 18.5 / 0.1 / 1.5 / 16.1 69.7 0.28 0.0 30 × Great Example 9 56.0 / 4.8 / 23.0 / 0.2 / 1.9 / 14.1 63.9 0.25 0.0 30 × Great Example 10 Al / Mo 60.0 / 3.7 / 22.0 / 0.1 / 1.1 / 13.1 61.2 0.14 0.0 30 × Good Example 11 59.0 / 4.8 / 18.5 / 0.1 / 1.5 / 16.1 62.9 0.19 0.0 30 × Good Example 12 56.0 / 4.8 / 23.0 / 0.2 / 1.9 / 14.1 60.1 0.14 0.0 30 × Good Example 13 Mo / Al-Nd /
Mo 60.0 / 3.7 / 22.0 / 0.1 / 1.1 / 13.1 65.2 0.43 0.0 30 × Great Example 14 59.0 / 4.8 / 18.5 / 0.1 / 1.5 / 16.1 45.9 0.35 -0.2 30 × Ordinary Example 15 56.0 / 4.8 / 23.0 / 0.2 / 1.9 / 14.1 64.8 0.42 0.0 30 × Great Example 16 Mo 60.0 / 3.7 / 22.0 / 0.1 / 1.1 / 13.1 76.2 0.40 - 100 × Great Example 17 59.0 / 4.8 / 18.5 / 0.1 / 1.5 / 16.1 77.4 0.37 - 100 × Great Example 18 56.0 / 4.8 / 23.0 / 0.2 / 1.9 / 14.1 76.8 0.35 - 100 × Great

In Table 2, for the aluminum alloy (Al-Nd) / molybdenum double membrane, aluminum / molybdenum double membrane, molybdenum / aluminum alloy / molybdenum triple layer, it contains phosphoric acid, nitric acid, acetic acid, etching regulator, etching inhibitor and water It can be seen that the composition for etching shows excellent etching characteristics.

Table 3 is an example showing the etching profile according to the thickness of the upper molybdenum film in the aluminum alloy (Al-Nd) / molybdenum double layer (Al-Nd / Mo) (Examples 19 to 27).

division Al-Nd / Mo
Thin film thickness
(A) Composition (% by weight)
(Phosphate / nitric acid / acetic acid / Cu (NO3) 2 / Glycine / water) Tilt angle
(˚) Unilateral CD loss
(Μm) Mo
protrusion
(Μm) O / E
ratio
(%) Residue
Whether Remarks Example 19 2000/300 60.0 / 3.7 / 22.0 / 0.1 / 1.1 / 13.1 64.5 0.25 0.0 30 × Great Example 20 59.0 / 4.8 / 18.5 / 0.1 / 1.5 / 16.1 69.7 0.28 0.0 30 × Great Example 21 56.0 / 4.8 / 23.0 / 0.2 / 1.9 / 14.1 63.9 0.25 0.0 30 × Great Example 22 2000/500 60.0 / 3.7 / 22.0 / 0.1 / 1.1 / 13.1 65.0 0.28 0.0 30 × Great Example 23 59.0 / 4.8 / 18.5 / 0.1 / 1.5 / 16.1 68.2 0.29 0.0 30 × Great Example 24 56.0 / 4.8 / 23.0 / 0.2 / 1.9 / 14.1 65.1 0.27 0.0 30 × Great Example 25 2000/700 60.0 / 3.7 / 22.0 / 0.1 / 1.1 / 13.1 66.7 0.28 0.0 30 × Great Example 26 59.0 / 4.8 / 18.5 / 0.1 / 1.5 / 16.1 69.5 0.28 0.0 30 × Great Example 27 56.0 / 4.8 / 23.0 / 0.2 / 1.9 / 14.1 64.2 0.29 0.0 30 × Great

In the case of etching using a conventional etching composition, as the thickness of the upper molybdenum becomes thicker, the electron transfer speed changes, and as a result, the performance of the etching regulator decreases, resulting in protrusion of the upper molybdenum (comparative example not shown). When etching using the etching composition according to the present invention, it was confirmed that there is no upper molybdenum protrusion and a good etching profile can be obtained.

As such, in the case of using the etching composition according to the present invention, even though there is a change in the film thickness in the thin film deposition process, it shows a strong and excellent etching profile can act as a great advantage in the operation of the process.

The etchant composition according to the present invention may be variously applied in a field requiring etching of a metal film, and in particular, may be used in various industrial fields, such as the manufacture of a transistor required to manufacture an electrode by etching.

1 is a photograph showing an etching profile after wet etching an aluminum-neodynium / molybdenum double layer using the conventional etching composition prepared in Comparative Example 1.

FIG. 2 is a photograph showing an etching profile after wet etching aluminum-neodynium / molybdenum bilayer using the etching composition prepared in Example 1 of the present invention.

Claims (11)

A composition for metal film etching comprising 50 to 65% by weight of phosphoric acid, 1 to 10% by weight of nitric acid, 10 to 25% by weight of acetic acid, 0.01 to 5% by weight of an etchant and a residual amount of water. The metal film etching composition of claim 1, wherein the etch regulator is an inorganic nitrate compound or sulfuric acid. The method of claim 2, wherein the inorganic nitrate-based compound is NH ₄ NO ₃ , Zn (NO ₃ ) ₂ , Co (NO ₃ ) ₂ , Ni (NO ₃ ) ₂ , Fe (NO ₃ ) ₃ , Cu (NO ₃ ) ₂ and AgNO _{3 The} metal film etching composition, characterized in that selected from the group consisting of. The metal film etching composition of claim 1, further comprising 0.01 to 5 wt% of an etch inhibitor based on the total weight of the composition. The method of claim 4, wherein the etching inhibitor is glycine (Glycine), alanine (Alanine), valine (Valine), Leucine (Leucine), Metopin (Methopnine), Isolencine, Phenylalanine (Phenylalanine), Tyrosine ( Tyrosine, Tryptophan, Serine, Threonine, Cysteine, Proline, Asparagine, Glutamine, Lysine, Arginine, Arginine, Composition for etching the metal film, characterized in that the amino acid compound selected from the group consisting of histidine (Histidine), aspartate and glutamate (Glutamate). The composition of claim 1, wherein the metal film is a single film selected from the group consisting of an aluminum film, an aluminum alloy film, and a molybdenum film, or a multilayer film in which the single film is laminated two or more times. . The metal film etching composition of claim 6, wherein the aluminum alloy film is a film made of an alloy of aluminum and neodymium (Al-Nd). The metal film etching composition of claim 6, wherein the metal film comprises at least one molybdenum film, and the etching inhibitor is a molybdenum etching inhibitor. The composition of claim 1, wherein the metal film is for forming a metal electrode pattern of a thin film transistor for a flat panel display. The metal layer etching composition of claim 9, wherein the metal electrode is a gate electrode or a data electrode. The metal film etching composition of claim 9, wherein the flat panel display is a liquid crystal display.

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