Ruthenium etching solution composition, pattern forming method using same, array substrate manufacturing method, and array substrate manufactured by the same

Abstract

To provide a ruthenium etchant composition that can etch only ruthenium metal film at high speed without RuO4 gas formation and has excellent storage stability at room temperature.SOLUTION: This invention relates to a ruthenium etchant composition containing periodic acid and ammonium ions, and having a pH of 6 to 7.5 or higher; a method for forming pattern including the step of etching a ruthenium metal film using the etchant composition; a method for manufacturing an array substrate for a display device including the method for forming pattern; and an array substrate for a display device manufactured by the method.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a ruthenium etchant composition, a pattern formation method including a step of etching a ruthenium metal film with the etchant composition, a manufacturing method for an array substrate for a display device including the pattern formation method, and an array substrate for a display device manufactured by the manufacturing method. [Background technology]

[0002] Ruthenium (Ru) has the properties of maintaining its conductivity even after oxidation without causing a decrease in capacity, and is relatively inexpensive. Therefore, it has recently attracted attention as a metal that can replace tungsten (W), which has traditionally been used to form gate electrodes, wiring, and barrier layers in thin-film transistors, and to fill contact holes and via holes.

[0003] In order to form wiring, via holes, etc. on a semiconductor substrate, a process of removing unnecessary parts while leaving only necessary parts is required. In particular, in recent years, a process of forming an electrode film in a narrow hole has been frequently adopted to reduce the occupied area of ​​a capacitor, and therefore there is a demand for the development of an etching solution composition capable of uniformly forming a thin ruthenium metal film in a narrow hole.

[0004] On the other hand, when etching a ruthenium metal film using an acidic etching solution composition, the toxic gas RuO 4 It is preferable to perform etching of a ruthenium metal film in a neutral to alkaline region because such RuO 4 If the pH of the etching solution composition is adjusted too high to prevent the generation of gas, the stability of periodic acid, which acts as an oxidizing agent, decreases, and the etching rate decreases. Therefore, a method of increasing the reaction temperature to prevent the decrease in the etching rate is conceivable, but the use of RuO 4The problem is that gases can also be generated when the reaction is carried out at high temperatures, which has created a need for compositions that have a suitable pH range and are capable of etching ruthenium metal films at room temperature.

[0005] In addition, in the semiconductor industry, since the process continuity is maintained by preserving several months' worth of raw materials, the etching solution composition should be able to be stably stored at room temperature for a long period of time. In particular, the ruthenium etching process can be performed using a single type of equipment, and the amount of etching solution used for one etching is relatively small, so the ruthenium etching solution can be stored in the equipment tank for a long period of time of more than three months. Therefore, the ruthenium etching solution composition is required to have excellent storage stability compared to etching solution compositions for other metals.

[0006] For example, Korean Patent Publication No. 10-2022-0051230 discloses a RuO 4 A gassing inhibitor is disclosed.

[0007] However, when etching a ruthenium metal film with an alkaline etching solution composition having a pH of 8 or more, RuO 4 Although the generation of gas can be suppressed, there is a problem in that the etching rate for the ruthenium metal film and the storage stability at room temperature are significantly decreased, resulting in a decrease in selectivity and usefulness for the ruthenium metal film.

[0008] Therefore, RuO 4 In reality, there is an ongoing demand for a ruthenium etching solution composition that is neutral or alkaline to suppress gas generation, yet has an appropriate pH to ensure an etching rate for a ruthenium metal film and storage stability at room temperature. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Korean Patent Publication No. 10-2022-0051230 Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention relates to RuO 4 The object of the present invention is to provide a ruthenium etching solution composition which is capable of etching only a ruthenium metal film at high speed without generating gas and has excellent storage stability at room temperature. [Means for solving the problem]

[0011] In order to achieve the above object, the present invention provides a ruthenium etching solution composition containing periodic acid and ammonium ions, the ruthenium etching solution composition having a pH of 6 or more and 7.5 or less. Effect of the Invention

[0012] According to the ruthenium etching solution composition of one embodiment of the present invention, the composition contains periodic acid and ammonium ions, and the pH of the composition is adjusted to 6 to 7.5, thereby oxidizing RuO 4 Even without the use of inhibitors, RuO 4 The production of can be suppressed.

[0013] In addition, according to the ruthenium etching solution composition according to one embodiment of the present invention, the etching rate for the ruthenium metal film can be further improved by containing periodic acid and ammonium ions and adjusting the pH of the composition to 6 to 7.5.

[0014] In addition, according to the ruthenium etching solution composition according to one embodiment of the present invention, the storage stability at room temperature can be further improved by adjusting the pH of the composition to 6 to 7.5. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The present invention contains periodic acid and ammonium ions, and adjusts the pH of the composition to 6 to 7.5, thereby forming RuO 4 Even without the use of inhibitors, RuO 4 The present invention relates to a ruthenium etching solution composition that can suppress the generation of ruthenium and further improve the etching rate for a ruthenium metal film and the storage stability at room temperature.

[0016] More specifically, it relates to a ruthenium etchant composition that includes periodic acid and ammonium ions.

[0017] The present invention also relates to a pattern forming method comprising the step of etching a ruthenium metal film using the etching solution composition, a method for manufacturing an array substrate for a display device comprising the pattern forming method, and an array substrate for a display device manufactured by the manufacturing method.

[0018] The ruthenium etchant composition of the present invention is particularly suitable for the technical field of selectively etching and removing a ruthenium metal film, and can be used to selectively and quickly remove only the ruthenium metal film from a microelectronic device including, for example, a silicon oxide film and an insulating material in addition to the ruthenium metal film.

[0019] Specifically, when a ruthenium metal film is etched with the ruthenium etching solution composition of the present invention, the etching rate of the ruthenium metal film may be 200 Å / min or more, and the reduction rate of the etching rate of the ruthenium metal film after 3 months at 20° C. to 25° C. may be 5% or less.

[0020] The ruthenium metal film to be etched by the etching solution composition of the present invention may mean a metal film containing ruthenium, and can be understood as a concept including, for example, a single film consisting of a ruthenium film, a ruthenium alloy film, or a ruthenium oxide film, and a multilayer film containing one or more films selected from the group consisting of the single film, a silicon film, and a barrier film.

[0021] In addition, the silicon film may include one or more selected from the group consisting of a silicon oxide film, a silicon nitride film, a silicon carbide oxide film, a silicon carbide film, and a silicon nitride film, and the barrier film may include one or more selected from the group consisting of a titanium nitride film and a tantalum nitride film.

[0022] The present invention will now be described in further detail. The terminology used in the present specification is intended to describe the embodiments only and is not intended to limit the present invention.

[0023] As used herein, the words "comprises" and "comprising" are used in a sense that does not exclude the presence or addition of one or more other components, steps, operations and / or materials other than the mentioned components, steps, operations and / or elements. Like reference numerals refer to like components throughout the specification.

[0024] <Ruthenium Etching Solution Composition> The ruthenium etching solution composition of the present invention contains periodic acid and ammonium ions, and may have a pH of 6 or more and 7.5 or less. The ruthenium etching solution composition of the present invention may further contain a hydroxide of a quaternary alkyl ammonium.

[0025] The periodic acid is provided to oxidize ruthenium to etch the ruthenium metal film, and ruthenium is converted to RuO 4 ― or RuO 4 2― When etching a ruthenium metal film using an acidic etching solution composition, the toxic gas RuO 4 However, the etching solution composition according to the present invention has a pH of 6 to 7.5 and is neutral to alkaline, so that separate RuO 4 Even without the use of inhibitors, RuO 4 One of the features of the method is that it is possible to selectively etch a ruthenium metal film without generating any oxide.

[0026] In one or more embodiments, the periodic acid is periodic acid (H 5 IO 6 or HIO 4 ) and salt forms thereof, and the salt form of the periodic acid includes, for example, potassium periodate (KIO 3 ), tetraethylammonium periodate (N(CH 2 CH 3 ) 4 IO 3 ) and tetrabutylammonium periodate (N(CH 2 CH 2 CH 2 CH 3 ) 4 IO 3 ), but is not limited to this.

[0027] In one or more embodiments, the content of periodic acid may be 0.1 to 5 wt %, preferably 0.5 to 3 wt %, based on the total weight of the etching solution composition. If the content of periodic acid is less than 0.1 wt % based on the total weight of the etching solution composition, the etching rate of the ruthenium metal film may decrease due to a decrease in the oxidizing power of periodic acid, and if it exceeds 5 wt %, the mixing stability may decrease.

[0028] The ammonium ion is NH 4 + and may be provided in order to adjust the pH of the etching solution composition according to the present invention and to promote etching of the ruthenium metal film by the periodic acid through electrical interaction with the anions on the surface of the ruthenium oxide film.

[0029] In one or more embodiments, the ammonium ion can be understood as a concept including a form in which the ammonium ion is bound to an anion so that the ammonium ion can be dissociated in an aqueous solution to generate an ammonium ion, and the anion can be, for example, acetate (C 2 H 3 O 4― ), sulfate (SO 4 2― ), sulfamate (H 2 NO 3 S ― ), formate (CHO 2 ― ), oxalato (C 2 O 4 2― ), benzoate (C 7 H 5 O 2 ― ), persulfate (SO 5 2― Or S 2 O 8 2― ), carbonate (CO 3 2― ), carbamates (NH 2 COO ― ), chloride (Cl ― ) and phosphate (PO 4 2― ), but is not limited to this.

[0030] In one or more embodiments, the form in which the ammonium ion is combined with the anion may be one or more of ammonium acetate, ammonium sulfate, ammonium sulfamate, ammonium formate, ammonium oxalate, ammonium benzoate, ammonium persulfate, ammonium carbonate, ammonium carbamate, ammonium chloride, and ammonium phosphate.

[0031] In one or more embodiments, the ammonium ion is ammonia (NH 3) and / or ammonium hydroxide (NH 4 In other words, the ammonium ion may be NH 4 + This refers only to the cation represented by the formula: ammonia (NH 3 ) to ammonium hydroxide (NH 4 OH) may not be included. Ammonia (NH 3 ) and / or ammonium hydroxide (NH 4 When ammonia (NHOH) is added as the ammonium ion, 3 ) and / or hydroxyl groups (OH ― ) may affect the pH of the etchant composition, decreasing the etch rate of the ruthenium metal film.

[0032] In one or more embodiments, the content of the ammonium ion or the compound having an anion bonded thereto may be 0.1 to 5 wt % based on the total weight of the etching solution composition, preferably 0.5 to 3 wt %. If the content of the ammonium ion (or the compound having an anion bonded thereto) is less than 0.1 wt % based on the total weight of the etching solution composition, the electrical interaction with the negative charge on the surface of the ruthenium oxide film may be insufficient, and the etching rate of the ruthenium metal film by periodic acid may decrease. If the content of the ammonium ion (or the compound having an anion bonded thereto) is more than 5 wt % based on the total weight of the etching solution composition, the content of the quaternary alkyl ammonium hydroxide described below must be increased in order to adjust the pH of the etching solution composition to 6 to 7.5, but the large steric hindrance of the quaternary alkyl ammonium hydroxide may prevent the surface of the ruthenium oxide film from corroding, thereby decreasing the etching rate of the ruthenium metal film.

[0033] The pH of the ruthenium etching solution composition of the present invention may be 6 or more and 7.5 or less. When the ruthenium etching solution composition of the present invention has an acidic pH of less than 6, ruthenium is converted by periodic acid into toxic and volatile RuO 4 On the other hand, if the pH exceeds 7.5, the stability of periodic acid drops sharply, which may reduce the etching rate of the ruthenium film, and periodic acid may oxidize to H 3 IO 6 2― , H 2 I 2 O 10 4― , H 2 IO 6 3― etc., the etching performance and storage stability of the etching solution composition at room temperature may decrease. In this case, the "room temperature" may mean 20°C to 25°C.

[0034] Conventional ruthenium etchant compositions include RuO 4 In order to suppress the generation of gas, it has generally been the case that the pH is 8 or more, which is in the neutral to alkaline region. However, when a ruthenium etchant composition with a pH of 8 or more is stored at room temperature for a certain period of time or more, the etching speed of the ruthenium film is significantly reduced compared to the initial value, which increases the cost of the ruthenium film etching process. Therefore, the ruthenium etchant composition of the present invention has a pH of 6 to 7.5, which is lower than pH 8, but does not cause RuO 4 The ruthenium etchant composition of the present invention is characterized by not generating gas and having improved storage stability at room temperature. Specifically, when a ruthenium metal film is etched using the ruthenium etchant composition of the present invention, the etching rate is 200 Å / min, preferably 300 Å / min or more, and even after 72 hours at 20° C. to 25° C., the etching rate reduction rate for the ruthenium metal film can be 10% or less, preferably 5% or less.

[0035] In one embodiment, the pH can be adjusted by the periodic acid and ammonium ions. Specifically, when the periodic acid is used alone, the pH is about 2, and the ammonium ions have a pKa of about 9.3 at 25° C., so that a person skilled in the art can adjust the pH of the etching solution composition to 6 to 7.5 by appropriately mixing the periodic acid and the ammonium ions in the range of 1 to 5% by weight, respectively, based on the total weight of the etching solution composition.

[0036] In another embodiment, the ruthenium etching solution composition of the present invention may further contain a hydroxide of quaternary alkyl ammonium in order to adjust the pH to 6 or more and 7.5 or less. Specifically, the hydroxide of quaternary alkyl ammonium is dissociated in an aqueous solution to produce hydroxide ions (OH ― ), which can play a role in adjusting the pH of the etching solution composition together with periodic acid and ammonium ions.

[0037] In one or more embodiments, the quaternary alkyl ammonium hydroxide may be, but is not limited to, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrahexylammonium hydroxide, tetraoctylammonium hydroxide, benzyltriethylammonium hydroxide, diethyldimethylammonium hydroxide, hexadecyltrimethylammonium hydroxide, and methyltributylammonium hydroxide.

[0038] In addition, the hydroxide of the quaternary alkyl ammonium is capable of reacting with the ammonium ion (NH 4 + It can also play a role in preventing corrosion of the ruthenium metal film by preventing electrical interaction between the ruthenium oxide film and the anions on the surface of the ruthenium oxide film.

[0039] In one or more embodiments, the content of the quaternary alkyl ammonium hydroxide may be 0.1 to 2 wt %, preferably 0.5 to 1 wt %, based on the total weight of the ruthenium etching solution composition. If the content of the quaternary alkyl ammonium hydroxide is outside the above range, the etching performance may be deteriorated and the process time may be extended.

[0040] The ruthenium etching solution composition of the present invention may be in the form of an aqueous solution containing water. The water is preferably deionized water for semiconductor processing, and more preferably deionized water having a resistivity of 18 MΩ / cm or more.

[0041] In one or more embodiments, the water may be included in a balance amount, which as used herein may mean an amount such that the weight of the total composition, including the essential components of the present invention and other components, is 100% by weight. Meanwhile, the ruthenium etching solution composition of the present invention may further contain other compounds within a range that does not impair the object of the present invention. ― It is preferable that the etching solution composition does not contain a compound that generates fluorine ions (F ― If a compound that generates ) is contained, there is a risk of causing damage to the underlying silicon film and barrier film.

[0042] In addition to the ruthenium etchant composition, the present invention includes a pattern forming method including a step of etching a ruthenium metal film with the ruthenium etchant composition, a method for manufacturing an array substrate for a display device including the pattern forming method, and an array substrate for a display device manufactured by the method.

[0043] <Pattern formation method> The present invention provides a pattern formation method comprising the step of etching a ruthenium metal film using an etching solution composition according to the present invention.

[0044] The pattern formation method can be appropriately performed by a person skilled in the art using a method known in the art, and may include, for example, the steps of forming a metal film on a substrate and immersing the substrate in the etching solution composition of the present invention using a batch type or single type etching device and / or spraying the etching solution composition of the present invention.

[0045] <Array substrate for display device and method for manufacturing said substrate> The present invention provides a method for manufacturing an array substrate for a display device, which includes the pattern forming method according to the present invention, and an array substrate for a display device manufactured by the method.

[0046] The array substrate for a display device may be manufactured by a known method for manufacturing an array substrate, except for using the etching solution composition according to the present invention. For example, in a method for manufacturing an array substrate including the steps of a) forming a gate electrode on a substrate, b) forming a gate insulating layer on the substrate including the gate electrode, c) forming a semiconductor layer (a-Si:H) on the gate insulating layer, d) forming source / drain electrodes on the semiconductor layer, and e) forming a pixel electrode connected to the drain electrode, the step a) or d) may include the steps of forming a ruthenium metal film on the substrate, and etching the formed ruthenium metal film using the etching solution composition according to the present invention.

[0047] The array substrate for a display device may include a substrate manufactured by the above-mentioned manufacturing method and an integrated element including the substrate, and may be, for example, a thin film transistor (TFT) array substrate.

[0048] Hereinafter, the present invention will be described in detail with reference to the embodiments. However, the present invention is not limited to the embodiments disclosed below, and may be realized in various different forms. The embodiments are provided only to complete the disclosure of the present invention and to fully inform those skilled in the art of the present invention of the scope of the invention, and the present invention is defined only by the scope of the claims.

[0049] Preparation of Ruthenium Etching Solution Compositions: Examples 1 to 31 and Comparative Examples 1 to 17 Ruthenium etching solution compositions of Examples 1 to 31 and Comparative Examples 1 to 17 were prepared, each containing the composition and the remaining amount of water as shown in Tables 1 and 2 below (unit: weight %).

[0050] [Table 1]

[0051] [Table 2]

[0052] A-1: Periodic acid A-2: Potassium periodate A-3: Tetraethylammonium periodate A-4: Tetrabutylammonium periodate B-1: Ammonium acetate B-2: Ammonium sulfate B-3: Ammonium sulfamate B-4: Ammonium formate B-5: Ammonium oxalate B-6: Ammonium benzoate B-7: Ammonium persulfate B-8: Ammonium carbonate B-9: Ammonium carbamate B-10: Ammonium chloride B-11: Ammonium phosphate C-1: Tetramethylammonium acetate C-2: Tetraethylammonium acetate C-3: Tetrabutylammonium acetate C-4: Ethyl acetate C-5: benzyl acetate D-1: Tetramethylammonium hydroxide Experimental Example (1) Evaluation of ruthenium film etching rate A ruthenium wafer on which ruthenium was deposited to a thickness of 300 Å was cut into a size of 3.0×3.0 cm to prepare a test piece. The test piece was immersed in the etching solution composition of Examples 1-31 and Comparative Examples 1-17 for 1 minute at 23° C. and 400 rpm. The test piece was then taken out, washed with water, and dried using air. The thickness of the ruthenium film after etching was measured by XRF analysis, and the etching rate of the ruthenium film was calculated based on the change in film thickness. At this time, the etching rate was evaluated according to the following criteria. The results are shown in Tables 3 and 4 below.

[0053] <Evaluation criteria> ◎: Etching speed 300 Å / min or more ○: Etching speed: less than 300 Å / min - 250 Å / min or more △: Etching speed: less than 250 Å / min to 200 Å / min or more X: Etching speed less than 200 Å / min (2) RuO 4 Gas generation evaluation 50 mL of the etching solution compositions of Examples 1 to 31 and Comparative Examples having a ruthenium film etching rate of 200 Å / min or more was placed in a bottle, and a test piece of a wafer on which ruthenium had been deposited to a thickness of 300 Å, cut into a size of 1.5×1.5 cm, was added to each bottle. After adding the test piece, the mouth of the bottle was sealed with a cap having a copper film attached, and the bottle was left at room temperature for 3 hours, after which discoloration of the copper film was confirmed with the naked eye. In the case of compositions having a ruthenium film etching rate of less than 200 Å / min, it did not appear that the ruthenium film was substantially etched, and RuO 4 Since it does not generate etching by-products containing RuO, it was excluded from the evaluation. 4 Whether or not gas was generated was evaluated according to the following criteria, and the results are shown in Tables 3 and 4.

[0054] <Evaluation criteria> ○: Discoloration of copper film (RuO 4 Gas generation) X: No discoloration of the copper film (RuO 4 (No gas generation) (3) Evaluation of storage stability The etching solution compositions of Examples 1 to 31 and Comparative Examples 1 to 17 used in Experimental Example (1) were stored at 23° C. for 3 months. After 3 months had passed, the ruthenium film etching rates of the etching solution compositions of Examples 1 to 31 and Comparative Examples 1 to 17 were measured again, and the storage stability was evaluated by calculating the rate of decrease in the etching rate of the ruthenium film before and after storage. At this time, the storage stability of the etching solution compositions was evaluated according to the following criteria, and the results are shown in Tables 3 and 4 below.

[0055] <Evaluation criteria> ◎: Etching rate reduction rate 0% ○: Etching rate decrease rate: over 0% to 3% or less △: Etching rate decrease rate is over 3% to less than 5% X: Etching rate decrease rate exceeds 5% (4) Evaluation of solubility The solubility of the components contained in the etching solution compositions of Examples 1 to 31 and Comparative Examples 1 to 17 was confirmed. If the solubility is reduced due to an inappropriate content ratio of each component, recrystallization / precipitation may be induced, and such reduced mixing stability may increase the possibility of impurity generation during the etching process. Here, the solubility of the components in the etching solution composition was evaluated by performing a transparency analysis of each etching solution composition using a UV-Vis spectroscopy device. The specific evaluation criteria are as follows. The evaluation results are shown in Tables 3 and 4 below.

[0056] <Evaluation criteria> ◎: 100% ○: 98% to less than 100% △: 95% to less than 98% X: Less than 95%

[0057] [Table 3]

[0058] [Table 4]

[0059] Referring to Tables 3 and 4, the etching solution compositions of Examples 1 to 31 contain periodic acid and ammonium ions and have a pH of 6 to 7.5, so that the ruthenium film etching rate is as high as 250 Å / min or more and RuO 4 It is seen that not only does it not generate gas, but it also has excellent storage stability and solubility.

[0060] On the other hand, in the case of the etching solution compositions of Comparative Examples 1 to 17 in which the content of periodic acid is out of the range of 0.1 to 5% by weight, the content of ammonium ions is out of the range of 0.1 to 5% by weight, or the pH is out of the range of 6 or more and 7 or less, relative to the total weight of the etching solution composition, the etching rate of the ruthenium film is slow, being less than 200 Å / min, or RuO 4Gas evolution or poor storage stability or solubility are found.

[0061] Therefore, in the case of the ruthenium etching solution composition of the present invention, RuO 4 This has the advantage that not only is the etching rate for ruthenium metal films significantly improved without generating gas, but also the storage stability at room temperature of 20°C to 25°C is significantly improved.

Claims

1. A ruthenium etchant composition comprising periodic acid and ammonium ions, The pH is 6 or more and 7.5 or less, The ammonium ion is ammonia (NH ３ ), ammonium iodide (NH 4 I), ammonium triiodide (NH 4 I 3 ), and ammonium iodate (NH 4 IO 3 ).

2. 10. The ruthenium etchant composition of claim 1 further comprising a quaternary alkyl ammonium hydroxide.

3. 2. The ruthenium etching solution composition according to claim 1, wherein the ruthenium metal film etching rate is 200 Å / min or more.

4. 2. The ruthenium etching solution composition according to claim 1, wherein the ruthenium metal film etching rate reduction rate after 3 months at 20° C. to 25° C. is 5% or less.

5. Based on the total weight of the etching solution composition, 0.1 to 5% by weight of the periodic acid; 0.1 to 5% by weight of the ammonium ion; and a balance of water.

6. A pattern forming method comprising a step of etching a ruthenium metal film using the etching solution composition according to any one of claims 1 to 5.

7. A method for manufacturing an array substrate for a display device, comprising the pattern forming method according to claim 6.

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