TWI759450B - Etching solution, etching method, and manufacturing method of display device - Google Patents

Abstract

The present invention provides an etching solution in which damage to IGZO is suppressed. The etching solution of the present invention contains hydroxyethanediphosphonic acid (A), phosphonic acid (B), hydrogen peroxide (C), nitric acid (D), fluorine compound (E), azole (F) and alkali (G) The etching solution is characterized in that: the phosphonic acid (B) contains diethylenetriamine pentamethylene phosphonic acid, N,N,N',N'-ethylenediamine tetramethylenephosphonic acid and amine One or more of the group consisting of oxytrimethylene phosphonic acid, the ratio of the hydroxyethane diphosphonic acid (A) is in the range of 0.01~0.1 mass %, and the ratio of the phosphonic acid (B) is 0.003~0.04 mass % % range.

Description

Etching solution, etching method, and manufacturing method of display device

The present invention relates to semiconductor technology, especially to the protective solution and etching solution of IGZO.

Indium gallium zinc oxide (IGZO) has been studied as an effective material as an oxide semiconductor material system. However, since IGZO is easily etched by acid or alkali, it is known that, when source-drain wirings are formed using these etchants, the IGZO serving as the base is corroded.

In order to overcome this problem, in the past, after forming a protective layer on IGZO, an etch stop type structure (refer to FIG. 1 ) was used to form the source-drain wiring, but the manufacturing became complicated, resulting in cost. increase. Therefore, in order to adopt a back channel etch type structure that does not require a protective layer (see FIG. 2 ), an etchant capable of etching various wiring materials while suppressing damage to IGZO is desired (see Non-Patent Document 1).

In addition, in recent years, as represented by 4K and 8K panels, the resolution of panels is rapidly progressing. As the resolution of the panel progresses, the wiring patterns for driving the pixels will become denser, and in order to reduce the loss of light irradiated from the backlight, the wiring width must be made thinner. On the other hand, in order to secure the amount of current flowing through the wiring, a wiring process capable of obtaining a suitable shape in terms of the cross-sectional area of the wiring is required. That is, an etchant that can process the taper angle of the wiring to be higher is desired.

As an etching solution for suppressing damage to IGZO, a chemical solution characterized by low pH as described in JP 2016-11342 A (Patent Document 1) is known, but sufficient IGZO has not been achieved yet. Corrosion resistance and workability.

[Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2016-11342

[Non-patent literature]

[Non-Patent Document 1] Kobe Steel Technical Report Vol.65, No.2, Sep.2015, "Oxide semiconductor material for BCE type TFT" by Shinya Morita et al.

Under such circumstances, it is desired to provide an etchant capable of etching a wiring material while suppressing damage to IGZO.

The present invention is as follows:

[1] An etching solution comprising hydroxyethanediphosphonic acid (A), phosphonic acid (B), hydrogen peroxide (C), nitric acid (D), fluorine compound (E), azole (F) and base (G) ), the aforementioned phosphonic acid (B) contains ethylene triamine pentamethylene phosphonic acid, N,N,N',N'-ethylenediamine tetramethylenephosphonic acid and aminotrimethylenephosphonic acid 1 or more of the formed groups, The ratio of the said hydroxyethane diphosphonic acid (A) is the range of 0.01-0.1 mass %, and the ratio of the said phosphonic acid (B) is the range of 0.003-0.04 mass %.

[2] The etching solution according to [1], wherein the phosphonic acid (B) is ethylenetriaminepentamethylenephosphonic acid.

[3] The etching solution according to [1] or [2], wherein the fluorine compound (E) is ammonium fluoride or acid ammonium fluoride.

According to an ideal aspect of the present invention, by using the etching solution of the present invention, the IGZO can be prevented from being corroded by acid and alkali, and it is not necessary to form a protective layer on the IGZO, so that the manufacturing cost can be greatly reduced. Therefore, a good substrate with a wiring structure having a high taper angle while preventing corrosion of IGZO in the etching step can be obtained. In particular, on IGZO, a structure having a multilayer thin film including a copper layer and a titanium layer can be processed particularly ideally by etching.

1: photoresist layer

2: wiring layer

3: Barrier layer

4: IGZO layer

5: cone angle

a: Top CD loss (a×2)

b: Bottom CD loss (b×2)

c: trailing tail (c×2)

[FIG. 1] It is an example of the schematic diagram of the TFT of the conventional etching stop type structure provided with the protective layer on IGZO.

FIG. 2 is an example of a schematic diagram of a TFT with a back-channel etched structure without a protective layer.

3] It is an example of the schematic diagram of the wiring cross section when the etching liquid of this invention is used.

FIG. 4 is an example of cross-sectional observation of IGZO when the etching solution of the example or the comparative example is used.

FIG. 5 is an example of surface observation of IGZO when the etching solution of the example or the comparative example was used.

The etching solution of the present invention can have corrosion resistance to IGZO by containing hydroxyethanediphosphonic acid (A) and specific phosphonic acid (B). In addition, by further containing hydrogen peroxide (C), nitric acid (D), fluorine compound (E), azole (F) and alkali (G), corrosion resistance to IGZO can be obtained, and at the same time, the wiring material can be improved. Etched composition.

Hereinafter, each component of the etching liquid of this invention is demonstrated in detail.

[Hydroxyethanediphosphonic acid (HEDP)(A)]

The hydroxyethanediphosphonic acid (A) is a compound represented by the formula (1).

The ratio of HEDP (A) in the etching solution is in the range of 0.01 to 0.1 mass %, preferably in the range of 0.03 to 0.08 mass %. By making the concentration range of HEDP (A) within this range, higher corrosion resistance of IGZO can be imparted, and roughening of the surface of IGZO can be prevented.

[phosphonic acid (B)]

By using phosphonic acid (B) together with HEDP (A), higher corrosion resistance of IGZO can be imparted, and the wiring shape can be processed into a high taper angle.

The phosphonic acid (B) in the present invention is selected from the group consisting of diethylenetriaminepentamethylenephosphonic acid, N,N,N',N'-ethylenediaminetetramethylenephosphonic acid and aminotrimethylenephosphine One or more phosphonic acids in the group consisting of acids. Among them, N,N,N',N'-ethylenediamine-methylenephosphonic acid has high corrosion resistance to IGZO, so it is preferable.

The ratio of the phosphonic acid (B) in the etching solution is in the range of 0.003 to 0.04 mass %, preferably 0.01 to 0.03 mass %, and more preferably in the range of 0.015 to 0.03 mass %. By making the concentration range of phosphonic acid (B) within this range, higher corrosion resistance of IGZO can be achieved.

[Hydrogen peroxide (C)]

Hydrogen peroxide (C) has a function of oxidizing copper as an oxidizing agent.

The ratio of hydrogen peroxide (C) in the etching solution is preferably in the range of 4.0 to 8.0 mass %, more preferably in the range of 4.5 to 7.5 mass %, and particularly preferably in the range of 5.0 to 6.5 mass %. By setting the concentration range of the hydrogen peroxide (C) within this range, the securing of the etching rate and the suppression of the local corrosion of the wiring can be appropriately performed.

[Nitric acid (D)]

The nitric acid (D) has an effect of dissolving copper after hydrogen peroxide has been used, and the like.

The ratio of nitric acid (D) in the etching solution is preferably in the range of 0.8 to 7.0 mass %, more preferably in the range of 1.5 to 6.5 mass %, and particularly preferably in the range of 2.0 to 6.0 mass %. By making the concentration range of nitric acid (D) within this range, a favorable etching rate can be ensured, and a favorable wiring shape can be obtained.

[Fluorine compound (E)]

The fluorine compound (E) has a function of etching a barrier layer made of a titanium-based metal.

The type of the fluorine compound (E) is not limited as long as it generates fluoride ions. Specific examples include hydrofluoric acid, ammonium fluoride, and acid ammonium fluoride, and among them, ammonium fluoride and acid ammonium fluoride are preferable because they have low toxicity. The fluorine compound (E) may be used alone or in combination of two or more.

The ratio of the fluorine compound (E) in the etching solution is preferably in the range of 0.2 to 0.8 mass %, more preferably in the range of 0.2 to 0.6 mass %, and particularly preferably in the range of 0.2 to 0.5 mass %. By setting the concentration range of the fluorine compound (E) within this range, a favorable etching rate for the barrier layer made of a titanium-based metal can be obtained.

[azole (F)]

The azole (F) is used to adjust the etching rate by pH. Specific examples of the azole (F) include 1,2,4-triazole, 1H-benzotriazole, 5-methyl-1H-benzotriazole, and 3-amino-1H-triazole azoles and other triazoles; 1H-tetrazole, 5-methyl-1H-tetrazole, 5-phenyl-1H-tetrazole, 5-amino-1H-tetrazole and other tetrazoles; 1,3-thiazole , 4-methylthiazole and other thiazoles. Among them, tetrazoles are preferred, and among them, 5-amino-1H-tetrazole is preferred from the viewpoint of not forming an insoluble salt with copper ions in a solution. The azoles (F) may be used alone or in combination of two or more.

The ratio of the azole (F) in the etching solution is preferably in the range of 0.05 to 0.35 mass %, more preferably 0.05 to 0.30 mass %, and particularly preferably 0.08 to 0.25 mass %. By making the concentration range of the azole (F) within this range, the etching rate can be appropriately adjusted, and a favorable wiring shape can be obtained.

[Alkali (G)]

The alkali (G) is used in order to adjust the etching rate by pH. The alkali (G) is not limited as long as it is a kind that is usually used to prepare an etching solution, and examples thereof include ammonia, potassium hydroxide, quaternary ammonium hydroxide, and an amine compound.

The amine compound includes alkylamines such as ethylamine and isopropylamine; alkanolamines typified by N-propanolamine and N-methylethanolamine; and diamines typified by ethylenediamine. Among them, quaternary ammonium hydroxide, N-propanolamine and N-butylethanolamine are preferable from the viewpoint of not deteriorating the stability of hydrogen peroxide. The base (G) may be used alone or in combination of two or more.

The ratio of the alkali (G) in the etching solution is preferably in the range of 0.6 to 10 mass %, more preferably in the range of 1.0 to 9.0 mass %, and particularly preferably in the range of 2.0 to 8.0 mass %. By making the concentration range within this range, the etching rate can be appropriately adjusted.

[other ingredients]

The etching solution of the present invention may contain additives, hydrogen peroxide stabilizers, surfactants, colorants, defoaming agents, etc., which have been conventionally used in etching solutions, within the range that does not impair the purpose of the present invention.

[Preparation method of etching solution]

The etching solution of the present invention is prepared by mixing HEDP (A), phosphonic acid (B), hydrogen peroxide (C), nitric acid (D), fluorine compound (E), azole (F), alkali (G) and according to needs To other components, add water (ideally ultrapure water) and stir until uniform.

The range of pH of the composition liquid is not particularly limited, but is usually 1.5 to 2.8, preferably 1.8 to 2.5. By making it within this range, corrosion resistance to IGZO can be suitably performed, and the wiring material can be etched at the same time.

[How to use the etching solution]

The object can be etched by bringing the etchant of the present invention into contact with the object.

The method for bringing the etching solution of the present invention into contact with the object is not particularly limited, and for example, a method of bringing the etchant of the present invention into contact with the object in the form of dropping (single-chip spin treatment) or spraying, or immersing the object in the present invention can be adopted. Invention of the method in the etching solution.

The temperature range of using the etching solution of the present invention is usually 10 to 70°C, preferably 20 to 50°C. The time for using the etching solution is usually 0.2 to 60 minutes. As the rinse solution after etching, any one of an organic solvent and water can be used.

[Semiconductor substrate]

The substrate which is the subject of the etching solution of the present invention preferably has IGZO, and IGZO is not particularly limited as long as it is a semiconductor composed of indium, gallium, zinc, and oxygen. The above-mentioned oxide may have an amorphous structure or may have crystallinity.

For example, when IGZO is used as an electronic element such as a thin film transistor (TFT: Thin Film Transistor), IGZO is formed on a substrate such as glass using a film formation process such as sputtering. Then, electrode patterns are formed by etching using a photoresist or the like as a mask. Then, copper (Cu), titanium (Ti), etc. are formed thereon by using a film-forming process such as sputtering, and then, source-drain electrodes are formed by etching using a photoresist or the like as a mask.

FIG. 3 is an example of a schematic diagram of a wiring cross section when the etching solution of the present invention is used. As shown in FIG. 3, a barrier layer (3), such as a titanium layer containing titanium, is interposed on the IGZO layer (4), and a wiring layer (2) composed of a copper layer containing copper has a structure with a multilayer thin film, which is ideal. The performance of the etching solution of the present invention is particularly effectively used in the wiring of display devices such as flat panel displays. According to an ideal aspect of the present invention, a desired wiring structure can be formed by using the photoresist layer (1) as a mask and etching the multilayer thin film using the etching solution of the present invention. In addition, in FIG. 3, twice the distance (a) from the end of the photoresist layer (1) to the end of the wiring layer (2) in contact with the photoresist layer (1) is referred to as the top CD loss (a× 2), 2 times the distance (b) from the end of the photoresist layer (1) to the end of the wiring layer (2) in contact with the barrier layer (3) disposed under the wiring (2) is called the bottom CD loss (b×2). Moreover, twice (c×2) of the distance (c) from the end of the wiring layer (2) to the end of the barrier layer (3) is called tailing. Moreover, the angle formed by the etching surface of the edge part of the wiring layer (2) and the IGZO layer (4) of the lower layer is called a taper angle (5).

[Example]

Hereinafter, the present invention will be specifically described with reference to examples, but the embodiments may be appropriately changed as long as the effects of the present invention can be exhibited.

In addition, unless otherwise specified, % means mass %.

[Substrate for evaluation]

<Substrate (1) for Etching Rate and Surface Condition Evaluation of IGZO>

The elemental ratio of indium (In), gallium (Ga), zinc (Zn) and oxygen (O) is 1:1:1:4 IGZO is formed on a glass substrate by sputtering with a film thickness of 1000Å (100nm). (100mm×100mm×1mm).

<Substrate (2) for Etching Performance Evaluation of Multilayer Thin Films Containing Copper Layer and Titanium Layer>

Titanium was sputtered on a glass substrate with a thickness of 25 nm to form a titanium layer, and then copper was sputtered with a thickness of 600 nm to laminate the copper layer of the wiring material. Then, a photoresist was coated, the pattern mask was exposed and transferred, and then developed to form a wiring pattern, and a multilayer film (100mm×100mm×1mm) including a copper layer and a titanium layer was fabricated on the glass substrate.

[Evaluation method] [Etch rate of IGZO (E.R.(Å/sec))]

After preparing a composition having the concentrations of (C), (D), (E), (F), and (G) components described in Table 1 or 2, 6000 ppm of copper powder and 150 ppm of titanium powder were added, respectively, and the mixture was stirred until Metal dissolves. After confirming that the metal was dissolved, components (A) and (B) were added at predetermined concentrations to prepare an etching solution. The etching was performed by immersing the substrate ( 1 ) at 35° C. for 20 seconds in the respective etching solutions. After that, it was washed with water and dried with nitrogen gas.

The film thickness after etching was measured by n & k Analyzer 1280 (n & k Technology Inc.), and the etching rate was calculated by dividing the difference in film thickness by the etching time, and the following criteria were used for determination.

E: The etching rate is less than 5Å/sec

G: The etching rate is more than 5Å/sec and less than 8Å/sec

P: The etching rate is more than 8Å/sec and less than 10Å/sec

B: Etching rate of 10Å/sec or more

E, G and P were rated as passable.

[IGZO surface condition]

The IGZO thin film after the etching rate of IGZO was measured was cut, and the surface roughness was observed using a scanning electron microscope (model: S5000H, manufactured by Hitachi, Ltd.) at a magnification of 50,000 times (accelerating voltage 2kV, accelerating current 10μA). situation, and use the following criteria to judge.

E: Smooth surface state

G: The surface is slightly rough, and when the IGZO cross section is observed with a scanning electron microscope, the difference between the concave and convex portions is less than 25 nm, or when the IGZO surface is observed with a scanning electron microscope, the number of voids per unit area (1200 nm × 1200 nm) is generated. less than 20

B: Significant roughness and voids occur on the surface. When the IGZO cross section is observed with a scanning electron microscope, the difference between the concave and convex portions is 25 nm or more, or when the IGZO surface is observed with a scanning electron microscope, the void portion per unit area (1200 nm×1200 nm) The number of occurrences is more than 20

E and G were rated as passable.

An example of cross-sectional observation of IGZO is shown in FIG. 4 , and an example of surface observation is shown in FIG. 5 .

[Etching performance for multilayer films comprising copper and titanium layers]

After preparing a composition having the concentrations of (C), (D), (E), (F), and (G) components described in Table 1 or 2, 6000 ppm of copper powder and 150 ppm of titanium powder were added, respectively, and the mixture was stirred until Metal dissolves. After confirming that the metal was dissolved, components (A) and (B) were added at predetermined concentrations to prepare an etching solution. The substrate ( 2 ) was immersed at 35° C. for 150 seconds and immersed in the respective etching solutions to perform etching, then washed with water, and then dried using nitrogen gas.

The multi-layer thin film sample comprising the copper layer and the titanium layer obtained by the above-mentioned etching method was cut, and a scanning electron microscope (Model: S5000H, manufactured by Hitachi, Ltd.) was used at a magnification of 50,000 times (acceleration voltage 2kV, accelerated Current 10 μA) to observe the cross section.

The taper angle 5 shown in FIG. 3 was measured based on the obtained SEM image, and the shape after etching was judged by the following reference|standard.

cone angle

E: Above 60° and less than 70°

G: 50 or more but less than 60°

B: less than 50° or more than 70°

E and G were rated as passable.

The evaluation results are shown in Tables 1 and 2.

In addition, the components in the table are as follows.

B1: N,N,N',N'ethylenediamine4methylenephosphonic acid

B2: Diethylenetriamine pentamethylenephosphonic acid

B3: amino trimethylene phosphonic acid

B4: Phosphoric acid

B5: Phosphonic acid

B6: Pentaethylene octamethylenephosphonic acid

E1: acid ammonium fluoride

F1: 5-amino-1H-tetrazole

G1: quaternary ammonium hydroxide

G2: Potassium Hydroxide

G3: N-butylethanolamine

G4: Ammonia

G5: 1-Amino-2-propanol

[industrial applicability]

The etchant of the present invention can be ideally used for etching of wiring materials in substrates containing IGZO. According to an ideal aspect of the present invention, a substrate with a wiring structure having a high taper angle while preventing corrosion of IGZO can be produced.

Claims (13)

An etching solution containing hydroxyethanediphosphonic acid (A), phosphonic acid (B), hydrogen peroxide (C), nitric acid (D), fluorine compound (E), azole (F) and alkali (G), the The phosphonic acid (B) contains a group selected from the group consisting of ethylenetriaminepentamethylenephosphonic acid, N,N,N',N'-ethylenediaminetetramethylenephosphonic acid and aminotrimethylenephosphonic acid One or more of the group, the fluorine compound (E) is one or more selected from the group consisting of hydrofluoric acid, ammonium fluoride and acid ammonium fluoride, and the azole (F) is selected from From 1,2,4-triazole, 1H-benzotriazole, 5-methyl-1H-benzotriazole, 3-amino-1H-triazole, 1H-tetrazole, 5-methyl-1H - at least one of the group consisting of tetrazole, 5-phenyl-1H-tetrazole, 5-amino-1H-tetrazole, 1,3-thiazole and 4-methylthiazole, the base (G) is one or more selected from the group consisting of ammonia, potassium hydroxide, quaternary ammonium hydroxide and amine compounds, the ratio of the hydroxyethane diphosphonic acid (A) is in the range of 0.01 to 0.1 mass %, the phosphine The ratio of the acid (B) is in the range of 0.003 to 0.04 mass %, the ratio of the hydrogen peroxide (C) in the etching solution is in the range of 4.0 to 8.0 mass %, and the ratio of the nitric acid (D) in the etching solution is 0.8 The ratio of the fluorine compound (E) in the etching solution is in the range of 0.2 to 0.8 mass %, and the ratio of the azole (F) in the etching solution is in the range of 0.05 to 0.35 mass %. The alkali (G) The ratio in an etching liquid is the range of 0.6-10 mass %. The etching solution of claim 1, wherein the phosphonic acid (B) contains diethylenetriaminepentamethylenephosphonic acid and N,N,N',N'-ethylenediaminetetramethylenephosphonic acid One or more of the formed groups. The etching solution of claim 1 or 2, wherein the phosphonic acid (B) is ethylenetriaminepentamethylenephosphonic acid. The etching solution of claim 1 or 2, wherein the ratio of the phosphonic acid (B) in the etching solution is in the range of 0.01 to 0.03 mass %. The etching solution according to claim 1 or 2, wherein the fluorine compound (E) is ammonium fluoride or acid ammonium fluoride. The etching solution according to claim 1 or 2, wherein the azole (F) is 5-amino-1H-tetrazole. The etching solution of claim 1 or 2, wherein the base (G) is selected from the group consisting of ammonia, quaternary ammonium hydroxide, potassium hydroxide, N-butylethanolamine, and 1-amino-2-propanol 1 or more of the group. The etching solution according to claim 1 or 2, wherein in the etching solution, the element ratio of indium (In), gallium (Ga), zinc (Zn) and oxygen (O) when 6000 ppm of copper and 150 ppm of titanium are dissolved in the etching solution is: 1:1:1:4, the etch rate of indium gallium zinc oxide at 35℃ is less than 10Å/sec. An etching method, comprising contacting an indium gallium zinc oxide (IGZO) substrate containing indium, gallium, zinc and oxygen with the etching solution according to any one of claims 1 to 8. An etching method, comprising: a substrate containing indium gallium zinc oxide (IGZO) containing indium, gallium, zinc and oxygen and a wiring material formed on the IGZO, and an etching solution according to any one of claims 1 to 8 The wiring material formed on indium gallium zinc oxide (IGZO) containing indium, gallium, zinc and oxygen is contacted and etched. An etching method by making a substrate containing indium gallium zinc oxide (IGZO) containing indium, gallium, zinc and oxygen, and a wiring layer and a barrier layer formed on the IGZO, as in any one of claims 1 to 8. Contact with the etchant to etch the barrier layer formed on indium gallium zinc oxide (IGZO) containing indium, gallium, zinc and oxygen. A method of manufacturing a display device, comprising: by making a substrate containing indium gallium zinc oxide (IGZO) containing indium, gallium, zinc and oxygen and a wiring material formed on the IGZO, and any one of claims 1 to 8 A step of etching the wiring material formed on the indium gallium zinc oxide by contacting the etchant. A method of manufacturing a display device, comprising: by making a substrate containing indium gallium zinc oxide (IGZO) containing indium, gallium, zinc and oxygen, and a wiring layer and a barrier layer formed on the IGZO, as in claim 1~ The step of etching the barrier layer formed on the indium gallium zinc oxide by contacting the etching solution in any one of 8.

Images