KR20050066395A - Etchant for indium oxide film etching, and etching method using the same - Google Patents

Abstract

The etchant composition of the indium oxide film according to the present invention, sulfuric acid as a main oxidizing agent; Compounds containing active oxygen as auxiliary oxidants; Compounds containing a halogen group element as a residue remover; And water.

Description

Etching liquid composition of indium oxide film and etching method using same {ETCHANT FOR INDIUM OXIDE FILM ETCHING, AND ETCHING METHOD USING THE SAME}

The present invention relates to an etching liquid composition capable of effectively etching an indium oxide film, that is, an indium zinc oxide (IZO) film, which is an oxide of indium and zinc stacked on various electronic component circuit boards and used as a transparent electrode.

IZO refers to an oxide in which In ₂ O ₃ and ZnO are mixed at an appropriate ratio.

The IZO transparent electrode is generally laminated on a glass substrate or the like through sputtering or the like, and a photoresist is coated thereon to form a pattern through an exposure and development process, and then the IZO film is etched to form a transparent electrode.

The IZO membrane is a substance which is not easily etched by a chemical reaction due to its excellent chemical resistance, and examples of the etchant that has been conventionally used for etching the IZO membrane include aqua regia (HCl + HNO ₃ ) etchant described in Korean Patent Publication No. 96-2903; An etchant consisting of one substance selected from hydrochloric acid, weak acid and alcohol described in JP-A-97-65685; Iron chloride-based (FeCl ₃ + HCl) etchant described in US Patent 5456795; Oxalic acid described in Unexamined-Japanese-Patent No. 2000-0017470, and the etching liquid whose salt or aluminum chloride is a main component, etc. are mentioned. In addition, US Patent 5340491 discloses an etching solution containing hydrogen iodide (HI) and iron chloride (FeCl ₃ ).

However, in the case of aqua regia etchant, the price of the etchant is cheap, but there is a problem that the etching solution composition fluctuates because the etching side of the pattern side is large and hydrochloric acid or nitric acid is volatilized after forming the etchant. In addition, in the case of the iron chloride-based etching solution, there is a problem that the fluctuation of the components appear to be the same as the aqua regia system because hydrochloric acid is the main etching solution. In addition, even though the etching solution made of oxalic acid is easily etched, there is a problem in that precipitates are generated at low temperatures with low solubility. In addition, the etching solution consisting of HI, the etching speed is high and the side etching is small, but the price is expensive, the toxicity and corrosiveness, there is a limit to use in the actual process.

On the other hand, the conventional etchant has a strong chemical activity, most of which is eroded by adjacent metals such as Al, Cr and less chemical resistance during etching to form a different film in the case of electronic components (eg, TFT-LCD) using a multilayer film There are many restrictions on the choice of materials.

Furthermore, in the case of the etching liquid containing hydrochloric acid, there is a fume causing a problem of air pollution due to the fume (fume), thereby increasing the cost of equipment and problems of safe operation.

Accordingly, an object of the present invention is to provide a selectivity ratio with other films during etching of an indium oxide film laminated on an electronic component substrate or the like (i.e., an index indicating the influence on the film quality other than the IZO film. To improve the reproducibility of the etching amount of the film quality and the etching process, to minimize the generation of the fume and to provide an etching liquid composition with high stability of the liquid with temperature.

Another object of the present invention is to provide an etching method of an IZO film.

In order to achieve the above object, the etching liquid composition of the indium oxide film (IZO film), in particular the indium oxide transparent conductive film according to the present invention is characterized in that it contains sulfuric acid, auxiliary oxidant, residue remover and water, more specifically Sulfuric acid as main oxidizing agent; Compounds containing active oxygen as auxiliary oxidants; Compounds containing a halogen group element as a residue remover; And water.

More specifically, the indium oxide film etching liquid composition according to the present invention comprises 1 to 15% by weight of sulfuric acid, 0.1 to 7.0% by weight of auxiliary oxidant, 0.01 to 3.0% by weight of residue remover, and the balance of the total weight of the composition. It is characterized by containing water.

According to a more preferred embodiment, the indium oxide etchant composition according to the present invention comprises 3 to 8% by weight of sulfuric acid, 0.3 to 5.0% by weight of co-oxidant, 0.05 to 2% by weight of residue remover and the total composition, based on the total weight of the composition. It is characterized by containing water such that the total weight is 100% by weight.

In the compositions according to the invention, sulfuric acid used as the main oxidizing agent can be prepared according to commonly known methods, and it is particularly preferred to have a purity for semiconductor processing.

Further examples of particularly suitable auxiliary oxidants for use in the IZO membrane etchant compositions according to the invention include compounds in the form of active oxygen, in particular oxone (gallium monopersulfate), K ₂ S ₂ O ₈ , Na ₂ S ₂ O ₈ , (NH ₄ ) ₂ S ₂ O ₈ , H ₂ O ₂ .

In addition, particularly suitable residue removers for use in the IZO membrane etchant compositions according to the invention are compounds in the form containing halogen elements, in particular NaF, NaHF ₂ , NH ₄ F, NH ₄ HF ₂ , NH ₄ BF ₄ , NH ₄ There is a compound selected from the group consisting of F-HF, KF, KHF ₂ , AlF ₃ , HBF ₄ , NaCl, NH ₄ Cl, KCl, AlCl ₃ , FeCl ₃ , MgCl ₂ . Preferably, the etchant composition according to the present invention in which FeCl ₃ , NH ₄ F, NaHF ₂ , HBF ₄ , KHF ₂ , NaCl, KCl, NH ₄ Cl, etc. is added as a residue remover, exhibits particularly excellent etching characteristics. Most preferred is FeCl ₃ .

Sulfuric acid, co-oxidants, and residue removers do not interfere with IZO film etching performance, and improve the selectivity with other films and the reproducibility of the etching process when etching indium oxide films stacked on electronic component substrates, etc. As long as it is possible to provide an etching solution which minimizes the stability of the liquid with temperature, it can be used in any mixing ratio. For example, the visual composition according to the present invention may contain 1 to 15% by weight of sulfuric acid, 0.1 to 7.0% by weight of auxiliary oxidant, and 0.01 to 3.0% by weight of residue remover based on the total weight of the composition, more preferably. Preferably, it may contain 3 to 8 wt% sulfuric acid, 0.3 to 5.0 wt% co-oxidant, and 0.05 to 2 wt% residue remover. Most preferably, the mixed weight ratio of sulfuric acid / auxiliary oxidizer / residue remover is 5/1 / 0.5 relative to the total weight of the composition. Other compositions to this invention add an appropriate amount of water so that the total weight of the composition is 100% by weight.

The water suitable for use in the etching liquid composition of the IZO membrane according to the present invention is not particularly limited, but preferably has a specific resistance value of 18 dl / cm or more, which is preferably deionized water, particularly preferably water showing the degree of ions removed from the water. Use deionized water.

On the other hand, the etchant composition according to the present invention may contain any additives commonly used in the art to improve the etching performance. Although it does not specifically limit to the example of the said additive, In general, surfactant, a metal ion blocking agent, etc. can be used. Surfactants may be added to the etchant composition to lower the surface tension to increase the etching uniformity, and examples of preferred surfactants include surfactants in a form compatible with the etchant, such as any anionic, Cationic, zwitterionic or nonionic surfactants. In addition, preferably, a fluorine-based surfactant may be added to the etchant composition according to the present invention as the surfactant. In addition to the above, those skilled in the art can select various other additives which are obviously known in the art, in order to further improve the effect according to the present invention.

The additive may be added in the range of preferably 0.0001% by weight to 0.01% by weight based on the total weight of the composition.

The etchant composition according to the present invention has excellent etching performance with respect to the IZO film (i.e., indium oxide film) used for electronic component substrates, etc., and reduces the attack (photoresist attack) of the photoreactive material during the etching process and leaves residues. Does not have excellent properties. In addition, the etchant composition according to the present invention has no crystallization phenomenon of oxalic acid at 0 ° C. or less, which is known as a problem of the conventional oxalic acid-based etching solution, and has no influence on the lower metal film appearing in the hydrochloric acid-based etching solution. Therefore, productivity can be improved in the manufacturing process ed of electronic components, such as a display apparatus using an IZO film | membrane.

On the other hand, the present invention also provides an etching method of the IZO film. The method according to the invention is characterized in that it comprises the following steps:

1) forming an IZO film on the substrate;

2) selectively leaving photoresist on the IZO film; And

3) etching using the etchant composition described above.

In the above method, step 1 may include fabricating a display device structure, in particular, a liquid crystal display device substrate on the substrate, and depositing an IZO film on the display device structure, in particular, a liquid crystal display device substrate. .

The substrate in step 1 is typically a glass substrate, a quartz substrate, or the like, which is mainly used for a display device, and is preferably a glass substrate. IZO films are prepared on a substrate by methods generally known to those skilled in the art, for example by sputtering, for example at a thickness of approximately 500 to 200 microns. Meanwhile, a structure for a display device may be added between the substrate and the IZO film. The structure for a display device is manufactured by a photo process, an etching process, or the like, including one or more films made of an organic insulating film, a method such as sputtering, or a semiconductor film, such as an amorphous or polycrystalline silicon film, by a method such as chemical sagittal deposition. Means the structure. It is also possible to carry out a conventional cleaning process on the substrate and deposit an IZO film.

In step 2, the "optionally" means that the photoreactive material such as photoresist is applied, and then only the photoreactive material is selectively exposed and removed using a mask.

Next, in order to form an indium oxide film at a selective site, a photoreactive material (for example, PR (Photoresist)) is applied, and selectively exposed using a mask to partially remove the photoreactive material with a developer. . For example, the photoresist is coated with a spin coater and coated with a thickness of about 1 μm. The photoreactive material may be a cathode or an anode reactant. In such a process, a conventional process such as ashing and heat treatment may also be added.

Next, an etching process of the indium oxide film is performed. The etching process may be performed according to methods well known in the art, and exemplifies dipping, spraying, and the like. During the etching process, the temperature of the etching solution is 20 ~ 50 ℃ and the proper temperature can be changed as needed by other processes and other factors.

Hereinafter, embodiments according to the present invention will be described in detail. These examples are provided to explain the invention in more detail, and the invention is not limited thereto.

Example 1

Sulfuric acid, which is a grade for semiconductor processing, and co-oxidant and residue remover described in Table 1 were mixed at a weight ratio of 5/1 / 0.5, and 25 ppm of an additive (fluorine-based surfactant; product name: FT-248, Bayer) was added. To prepare an etching solution, a deionized water was added to a total of 100% by weight. The etching process deposits an indium oxide film on the glass substrate by sputtering to a thickness of about 500 kPa, coats a photoresist of about 1 μm on it, and selectively forms a pattern on which the test piece is etched by spraying on the above-described etching solution. It was. The etching temperature was about 40 ° C., and the etching rate was about 10 μs / sec.

Examination of the specimens with SEM images showed good photoresist and residue characteristics.

Examples 2 to 26

Using the substrate which has an IZO film | membrane, it carries out by the same method as Example 1 except using the etching liquid manufactured by combining sulfuric acid, the auxiliary oxidizing agent of Table 1, and the residue remover by the composition ratio of Table 1. The results are shown in Table 1. The etching liquid compositions of the indium oxide film of this embodiment, in which the content of each component had the composition ratio defined in the present invention, showed good results with no effect on the photoresist and no residue.

Comparative Examples 1 to 5

An etching solution was prepared in the same manner as in Example 1 except that the etching solution prepared by combining sulfuric acid, the auxiliary oxidizing agent and the residue remover shown in Table 2 in the composition ratios shown in Table 2 was used to evaluate the etching performance. The results are shown in Table 2. It can be seen that the etchant of the comparative example, in which the content of each component does not have a composition ratio defined in the present invention, exhibits metal etching residue generation, stain generation and partial etching and poor etching profiles.

In the following table, the term "photoresist attack" refers to a change in the photoresist pattern that occurs when etching is performed after the photoresist is applied on the metal layer and the photoresist is selectively left.

Example Composition (% by weight) (sulfuric acid / oxone / NH4F) Residue Photoresist Attack One 1/1 / 0.5 X X 2 5/1 / 0.5 X X 3 10/1 / 0.5 X X 4 15/1 / 0.5 X X 5 10 / 0.1 / 0.5 X X 6 10 / 0.5 / 0.5 X X 7 10/2 / 0.5 X X 8 10/5 / 0.5 X X 9 10/7 / 0.5 X X 10 10/2 / 0.01 X X 11 10/2 / 0.1 X X 12 10/2/1 X X 13 10/2/3 X X Sulfuric acid / hydrogen peroxide / KCl 14 1/1 / 0.5 X X 15 5/1 / 0.5 X X 16 10/1 / 0.5 X X 17 15/1 / 0.5 X X 18 10 / 0.1 / 0.5 X X 19 10 / 0.5 / 0.5 X X 20 10/2 / 0.5 X X 21 10/5 / 0.5 X X 22 10/7 / 0.5 X X 23 10/2 / 0.01 X X 24 10/2 / 0.1 X X 25 10/2/1 X X 26 10/2/3 X X

Comparative example Composition (% by weight) (sulfuric acid / oxone / NH4F) Residue Photoresist Attack One 5 / 0.1 / 0 O X 2 5 / 0.01 / 0.1 Bad profile X 3 5/0 / 0.1 Partial etching X 4 0.5 / 0.5 / 0.1 Not etched X 5 25 / 0.5 / 0.1 X O

<Selectivity and Comparative Test of Etching Solution>

Comparative Example 6

Hydrochloric acid and nitric acid were mixed at a weight ratio of 18/5, 25 ppm of fluorine-based surfactant was added as an additive, and deionized water was added in an amount of 100% by weight in total to prepare aqua regia-based IZO membrane etchant.

Comparative Example 7

Ferric chloride and hydrochloric acid are mixed at a weight ratio of 22/10, 25 ppm of an additive (fluorine-based surfactant) is added, and deionized water is added to an amount of 100% by weight in total to prepare a conventional ferric chloride IZO membrane etching solution. Manufactured.

Comparative Example 8

5% by weight of oxalic acid was added and 25 ppm of an additive (fluorine-based surfactant) was added, followed by adding deionized water in an amount of 100% by weight in total to prepare a conventional oxalic acid-based IZO membrane etchant.

In Comparative Example 6-8, the etching liquid in Example was prepared with a specimen in which the different film quality (Al-Nd lamination thickness: 2000 kPa, Cr: 1500 kPa, SiNx: 3000 kPa, a-Si: 1500 kPa) was laminated to each etchant. The etching solution was irradiated by spraying for a certain time. In addition, the etching amount of the film quality was measured using SEM. The results are shown in Table 3 and FIG. 1.

Etch solution type Comparative Example 6 Comparative Example 7 Comparative Example 8 Example 7 Example 8 Example 9 Treatment temperature (℃) 40 40 40 60 60 60 Processing time (sec) 100 100 100 100 100 100 Etching amount of various membranes (%) ITO 100 100 100 100 100 100 IZO 100 100 100 100 100 100 Al-Nd 100 100 12 0 0 2 Cr 0 0 0 0 0 0 SiNx 0 0 0 0 0 0 a-Si 0 0 0 0 0 0

The etching solution of Comparative Examples 6 and 7, which is a conventional etching solution, was treated at a temperature of 40 ° C., which is a general treatment temperature applied in a mass production line, because the fume was generated even at room temperature and the composition of the liquid was changed. ), But was treated at 40 ℃ to suppress the precipitation of crystals.

 As can be seen from the above table, it can be seen that the conventional aqua regia etchant or ferric chloride etchant heavily affects Al-Nd while the IZO film is etched, and in the case of etching according to the present invention, You can see that. To increase the selectivity of IZO film and Al-Nd, the IZO film was etched 100% and the Al-Nd film was less than 2%.

As described above, the etchant composition according to the present invention provides an etchant having no attack on a photoreactive material such as a photoresist during the etching process and no residue after the etching process, thereby manufacturing an electronic component substrate such as a display device. Productivity can be improved.

1 is a view showing a SEM image (A) of etching the film quality in a conventional aqua regia and an SEM image (B) of the etching solution composition according to the present invention (as shown in Figure 1, etching with aqua regia etchant In one case, the CD-loss is large).

Claims (8)

An indium oxide film (IZO (Indium Zinc) comprising 1 to 15% by weight of sulfuric acid, 0.1 to 7.0% by weight of auxiliary oxidizing agent, 0.01 to 3.0% by weight of residue removing agent, and residual amount of water, based on the total weight of the composition. Oxide) membrane) etching solution composition. The compound according to claim 1, which is 1 to 15% by weight of sulfuric acid, 0.1 to 7.0% by weight of a compound having active oxygen as an auxiliary oxidant, and 0.01 to 3.0% by weight of a compound containing a halogen element as a residue remover. %, And a residual amount of water, the etching liquid composition of the indium oxide film. The method of claim 2, wherein the active oxygen-containing compound is oxone (gallium monopersulfate), K ₂ S ₂ O ₈ , Na ₂ S ₂ O ₈ , (NH ₄ ) ₂ S ₂ O ₈ , H ₂ O Etching liquid composition of the indium oxide film, characterized in that selected from the group consisting of _two . The compound according to claim 2, wherein the compound containing the halogenated element is NaF, NaHF ₂ , NH ₄ F, NH ₄ HF ₂ , NH ₄ BF ₄ , NH ₄ F-HF, KF, KHF ₂ , AlF ₃ , HBF ₄ , NaCl, NH ₄ Cl, KCl, AlCl ₃ , FeCl ₃ , MgCl ₂ The etching liquid composition of the indium oxide film, characterized in that selected from the group consisting of. The etchant composition of claim 2, wherein the water is deionized water.  The etchant composition according to claim 2, further comprising an additive selected from the group consisting of surfactants, metal ion sequestrants and corrosion inhibitors. An etching method of etching the formed IZO film during the manufacturing process of an electronic component substrate comprising forming an IZO film, the etching method comprising: 1) forming an IZO film on the substrate; 2) selectively leaving a photoresist material on the IZO film; And 3) etching by applying the etchant composition according to any one of claims 1 to 6. The etching method according to claim 7, wherein the electronic component substrate is an element substrate for a liquid crystal display.