JP2013058629A - Etchant for copper and copper alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stable and long-life etchant composition which is superior in practicability and which enables the etching of a metal multilayer film pattern including a copper layer, a copper oxide layer and/or a copper alloy layer with good accuracy, and allows the formation of good sectional shape, and to provide an etching method with the etchant composition.SOLUTION: The etchant composition is used for etching a metal multilayer film having a copper layer, a copper oxide layer and/or a copper alloy layer. The etchant composition comprises: 0.1-80 wt.% of persulfate and/or persulfuric acid solution; 0.1-80 wt.% of phosphoric acid; and 0.1-50 wt.% of nitric acid and/or sulfuric acid. Adding chloride ions or ammonium ions to the etchant composition, it becomes possible to easily control the etching rate and the sectional shape. Also, the invention relates to an etching method using the etchant composition.

Description

  The present invention relates to an etching composition for etching a metal laminated film of copper and a copper alloy containing copper as a main component used in the manufacture of flat panel displays and the like, and an etching method using such an etching solution.

  Conventionally, an aluminum thin film has been used as a fine wiring material for liquid crystal display devices, but copper or copper is mainly used to form a drive transistor electrode and a fine pattern of a flat panel display with a line width of several microns or less. Until recently, copper alloys as components have not been used. Therefore, a copper thin film etching technique having a line width of several microns or less suitable for flat panel manufacturing has been limited so far.

  When a copper thin film is used as an electrode, copper is not used as a single layer, but a metal such as Ti, Mo, or MoTi is used as an adhesion layer or barrier for the purpose of improving adhesion to a glass substrate or barriering copper diffusion. Need to be used as a layer. In that case, in general, it has been attempted to use it for an electrode as a laminated film of Ti / Cu / Ti, Cu / Ti, Mo / Cu / Mo, Cu / Mo, MoTi / Cu / MoTi, Cu / MoTi, Various film etching methods have also been studied.

  Patent Document 1 describes a hydrogen peroxide-acetic acid-based etching solution as an etching solution for a copper single film or a copper-molybdenum multilayer film. There is a problem that the change with time is large and control is difficult. In addition, the hydrogen peroxide solution has a short life, and it is necessary to dissolve copper as a pretreatment to stabilize the performance, and the waste solution after etching is due to gas generation due to decomposition of the hydrogen peroxide solution. There is a risk of explosion of containers during storage. Furthermore, the hydrogen peroxide system is often used for batch etching of Cu / Ti and Cu / Mo laminated films, but also contains a fluorine compound, so that the material cost is low, such as the substrate cannot be reused due to glass corrosion. There are increasing problems.

  A phosphoric acid-nitric acid-acetic acid based etching solution used for etching an aluminum film, which has been used as a wiring material in the past, can also dissolve a copper film, but the solution can easily penetrate between the resist and Cu, and the copper under the resist Since the etching is easy to proceed and the higher the spray flow rate, the lower the etching rate. Further, for example, when used for a laminated film of Cu / Mo or the like, it is difficult to obtain a good pattern shape such that one metal is extremely easily melted due to the influence of the battery effect due to the difference in corrosion potential between the laminated film layers.

  The copper chloride-hydrochloric acid-based or iron chloride-hydrochloric acid-based etching solution described in Patent Document 2 has an etching rate higher than that of copper when the cross-sectional shape of copper is almost vertical and a copper alloy is present in the lower layer. Therefore, there is a problem that the etching of the lower layer proceeds and a reverse taper shape tends to be formed.

  In Patent Documents 2 to 5, etching of a copper single layer and a laminated film such as Cu / Ti or Cu / Mo with an etching solution containing a persulfate is studied.

  Recently, a laminated film containing a copper alloy has been developed as a laminated film replacing the Cu / Ti or Cu / Mo laminated film. Unlike conventional laminated films that use different types of metal films, these are laminated films of a copper layer and a copper alloy layer, which not only excel in performance as a base film, but also have the same layer in the film forming process. It has the merit that the film can be formed by the apparatus.

  However, almost no investigation has been made on a method capable of effectively etching a laminated film having a copper layer and a copper oxide layer and / or a copper alloy layer and an etching solution used therefor. Patent Document 6 discloses an etching solution for a laminated film having a copper oxide layer and a copper alloy oxide layer containing a peroxide and an organic acid, and persulfate and persulfate are shown as the peroxide. Has been. However, in a composition containing persulfuric acid or a persulfate salt and an organic acid, the solubility of copper is greatly lowered due to the influence of the organic acid, so that it is difficult to adjust the target treatment time. In order to cope with this, it is necessary to increase the amount of persulfuric acid or persulfate to promote the solubility. However, if these amounts are increased, the etching solution easily penetrates between the resist and copper or copper alloy. Peeling occurs and patterning becomes difficult. Actually, the example described in Patent Document 6, a composition comprising ammonium persulfate, acetic acid and ammonium acetate was prepared, and the copper / copper alloy substrate was etched. As a result, the resist was removed before the copper etching was completed. It was impossible to pattern. The reason why the substrate could be processed with the composition described in Patent Document 6 was that it was a copper alloy / copper alloy substrate called a CuMg / CuMgO substrate, and the copper alloy was a laminated film having higher solubility than copper. It is thought that it was able to process all at once. In addition, it is considered that the copper alloy / copper alloy is easy to batch-process because the solubility is similar to that of the copper / copper alloy substrate. As described above, the copper / copper alloy laminated film cannot obtain a desired shape even if an etching solution known in general is used due to a difference in etching characteristics (solubility).

JP 2004-193620 A JP 2010-87213 A JP 2010-265547 A Japanese Patent No. 3974305 Japanese Patent Laid-Open No. 11-140669 JP 2010-265524 A

  That is, the subject of this invention is providing the etching liquid composition which can control an element important for the batch etching of a laminated film in the etching of the laminated film which has copper and a copper alloy.

  In order to solve the above-mentioned problems, the present inventor has intensively studied and made a copper laminated film including a copper thin film and a copper alloy containing copper as a main component, an adhesion layer, and a barrier layer as a persulfate and / or We have found that good cross-sectional shapes can be obtained by etching with an etchant composition in which phosphoric acid and nitric acid and / or sulfuric acid are added to a persulfuric acid solution. It came.

That is, the present invention relates to the following.
(1) Etching for etching a metal laminated film having a copper layer and a copper oxide layer and / or a copper alloy layer (except for copper and molybdenum, copper and titanium, and copper and chromium, respectively) A liquid composition comprising:
The etching solution comprising a persulfate solution and / or a persulfate solution 0.1 to 80% by weight, phosphoric acid 0.1 to 80% by weight, and nitric acid and / or sulfuric acid 0.1 to 50% by weight Composition.
(2) The above-mentioned (1), wherein the persulfate solution is an aqueous solution containing one or more kinds of potassium peroxomonosulfate, potassium hydrogen peroxysulfate (KHSO ₅ ), ammonium peroxodisulfate or potassium peroxodisulfate. The etching liquid composition as described in).
(3) The etching solution composition as described in (1) or (2) above, wherein the persulfate solution and / or the persulfate solution contains potassium peroxysulfate (KHSO ₅ ).

(4) The persulfuric acid solution contains one or more kinds of potassium peroxomonosulfate, ammonium peroxodisulfate, and potassium peroxodisulfate, and the active oxygen is 0.01 to 5% by weight, The etching liquid composition in any one of 1)-(3).
(5) The etching solution composition according to any one of (1) to (4), which does not contain nitric acid.
(6) The etching solution composition according to any one of (1) to (5) above, further containing 0.00001 to 30% by weight of chloride ions.
(7) The etching solution composition according to any one of (1) to (6) above, further containing 0.1 to 50% by weight of ammonium ions.

(8) The metal laminated film has a layer configuration of copper / copper alloy or copper alloy / copper / copper alloy, and the copper alloy is in contact with the substrate, according to any one of (1) to (7) above. Etching solution composition.
(9) The etching solution composition according to any one of (1) to (8), wherein the copper alloy is copper-magnesium-aluminum or copper-magnesium-aluminum oxide.
(10) The etchant composition according to any one of (1) to (9), for etching the drive transistor electrode in a flat panel display.

(11) A method for etching a metal laminated film having a copper layer and a copper oxide layer and / or a copper alloy layer (excluding copper alloys composed of copper and molybdenum, copper and titanium, and copper and chromium). The said etching method including the process of etching using the etching liquid composition in any one of said (1)-(10).
(12) The etching method according to (11), wherein the metal laminated film has a layer configuration of copper / copper alloy or copper alloy / copper / copper alloy, and the copper alloy is in contact with the substrate.
(13) The etching method according to (11) or (12), wherein the copper alloy is copper-magnesium-aluminum or copper-magnesium-aluminum oxide.
(14) The etching method according to any one of (11) to (13), wherein the driving transistor electrode is etched in the flat panel display.

  According to the etching method of the present invention, a metal laminated film of copper and a copper oxide layer and / or a copper alloy containing copper as a main component is formed with a metal thin film fine pattern having a line width of about 0.5 to 5 μm. Even if it exists, it can etch accurately. With only persulfate and / or persulfate solution, the cross-sectional shape becomes vertical and the surface of the cross-section becomes rough, and the lower layer copper alloy has low solubility, so the lower layer tends to protrude. In the etching solution composition of the present invention, the persulfate and / or persulfate solution, phosphoric acid, nitric acid and / or sulfuric acid are combined to form a copper layer, a copper oxide layer and / or Alternatively, the metal laminated film including the copper alloy layer can be etched into a favorable forward tapered shape.

In addition, the etching rate and the taper angle can be controlled, and etching with high in-plane uniformity with suppressed side etching and generation of residues is possible.
Furthermore, a good cross-sectional shape can be obtained even by using a dip type or a spray type, and in the case of the spray type, the etching rate increases with an increase in the flow rate of the spray, so that it is easy to use and excellent in practicality.

  In particular, the laminated film in which the copper alloy is copper-magnesium-aluminum (Cu-Mg-Al) or copper-magnesium-aluminum oxide (Cu-Mg-Al-O) is the main film from the viewpoint of adhesion and barrier properties. In the copper laminated film most noticed by the inventors, the etching solution composition of the present invention can achieve a fine pattern formed by etching.

FIG. 1 is a SEM photograph of the cross section of the substrate after the etching process in Examples 1-8. FIG. 2 is a SEM photograph of the cross section of the substrate after the etching process in Examples 9 to 19. FIG. 3 is a SEM photograph of the cross section of the substrate after the etching process in Examples 20 to 36. FIG. 4 is SEM photographs of two types of substrate cross-sections having different film thicknesses after the etching process in Example 54. FIG. 5 is an SEM photograph of the cross section of the substrate after the etching process in Examples 55-58. FIG. 6 is an SEM photograph of the cross section of the substrate after the etching process in Examples 59-62. FIG. 7 is a SEM photograph of the cross section of the substrate after the etching process in Examples 63 to 66. FIG. 8 is an SEM photograph of the cross section of the substrate after the etching process in Example 67 and Comparative Example 1.

One aspect of the present invention is to etch a metal laminated film having a copper layer and a copper oxide layer and / or a copper alloy layer (except for copper and molybdenum, copper and titanium, and copper alloys composed of copper and chromium). An etching solution composition for
The etching solution comprising a persulfate solution and / or a persulfate solution 0.1 to 80% by weight, phosphoric acid 0.1 to 80% by weight, and nitric acid and / or sulfuric acid 0.1 to 50% by weight Relates to the composition.

  The copper alloy in the present invention is a copper alloy containing copper as a main component and containing copper and an arbitrary metal, and includes a copper alloy oxide. Preferably, copper is contained at 80 atomic percent or more, and Cu—Ca, Cu—Mg, Cu—Ca—O, Cu—Mg—O, Cu—Al, Cu—Zr, Cu—Mn, Cu—Ni—B, Cu -Mn-B, Cu-Ni-B, Cu-Si, Cu-Al, Cu-Mo, Cu-Al, Cu-Mg-B, Cu-Ti-B, Cu-Mo-B, Cu-Al-B Cu-Si-B, Cu-Mg-Al, Cu-Mg-Al-O, and the like. However, copper alloys composed of copper and molybdenum, copper and titanium, and copper and chromium are excluded. Cu-Mg-Al and Cu-Mg-Al-O are preferred in that a particularly good tapered shape can be obtained.

  The metal laminated film in the present invention includes a copper layer, a copper oxide layer, and / or a copper alloy layer (excluding copper alloys composed of copper and molybdenum, copper and titanium, and copper and chromium). The lamination is typically two layers, but even if there are three or more layers, batch etching can be performed. Typically, the two-layer substrate has a copper / copper alloy layer configuration, the three-layer substrate has a copper alloy / copper / copper alloy layer configuration, and both have a layer configuration in which the copper alloy is in contact with the substrate. Here, the substrate may include, but is not limited to, any material that is desired to be patterned on its surface as an insulating material or semiconductor, such as a resin such as glass, silicon, ceramic, polyimide, etc. Glass or silicon.

In the present invention, the persulfate solution is an aqueous solution containing peroxomonosulfate and / or peroxodisulfate. Examples of the persulfate include, but are not limited to, potassium peroxomonosulfate, peroxysulfuric acid. Potassium hydrogen (KHSO ₅ ), sodium peroxomonosulfate (NaHSO ₅ ), ammonium peroxodisulfate ((NH ₄ ) ₂ S ₂ O ₈ ), potassium peroxodisulfate (K ₂ S ₂ O ₈ ), sodium peroxodisulfate (Na ₂ S ₂ O ₈ ) and the like.

From the standpoint of solubility, the persulfate solution is preferably potassium peroxomonosulfate, ammonium peroxodisulfate ((NH ₄ ) ₂ S ₂ O ₈ ) and potassium hydrogen peroxysulfate (KHSO ₅ ) The term “potassium peroxomonosulfate” In general, and used herein to mean the mixed triple salt 2KHSO ₅ · KHSO ₄ · K ₂ SO ₄ . The term “KHSO ₅ ” is used herein to mean in particular potassium hydrogen peroxysulfate.
Potassium peroxomonosulfate is known by a product name such as oxone, and this persulfate is more preferable because it has high solution stability.

In the present invention, persulfuric acid solution means potassium peroxomonosulfate, potassium peroxysulfate (KHSO ₅ ), sodium peroxomonosulfate (NaHSO ₅ ), ammonium peroxodisulfate ((NH ₄ ) ₂ S ₂ O ₈ ), peroxodisulfate. Including persulfate such as potassium sulfate (K ₂ S ₂ O ₈ ), sodium peroxodisulfate (Na ₂ S ₂ O ₈ ), active oxygen is 0.01 to 5% by weight, preferably 0.3 to 3% by weight %, More preferably 0.5 to 2% by weight aqueous solution.

  Potassium peroxomonosulfate as a solid has a theoretical active oxygen content of 5.2%, but as a commercially available solid triple salt, it has a typical active oxygen of about 4.7%. It is recognized that the purity of commercially available potassium peroxomonosulfate is about 95-98% due to minor impurities, minor amounts of additives and variations in the manufacturing process.

  “Active oxygen” is defined as the amount of oxygen in the potassium peroxomonosulfate triple salt that exceeds the amount of oxygen required to form the corresponding hydrogen sulfate. It may be calculated as a percentage from the equation for the decomposition of potassium peroxomonosulfate.

In the formula, [O] is oxygen liberated by the decomposition shown. In applying the given formula, the weight of KHSO ₅ is replaced by the weight of the sample in which the impurity material is used. The active oxygen can of course be determined from a number of reactions, for example displacement of iodine from potassium iodide which is quantitative.

(Measurement of active oxygen)
The measuring method of active oxygen is performed according to JP 2009-539740, and is determined by standard iodine titration. The solution to be analyzed is diluted with cold deionized water, acidified, treated with potassium iodide, and titrated with a standardized 0.1N sodium thiosulfate reagent to the end point as viewed by the starch indicator. The active oxygen content is calculated as follows.

% Active oxygen = (mL _titrant x normality _titrant x 0.8) / (gram _sample )
Similarly, the% KHSO ₅ concentration may be calculated by:
% KHSO ₅ =% active oxygen / 0.105

  The concentration of the persulfate and / or persulfate solution is 0.1 to 80% by weight, preferably 5 to 35% by weight. If the concentration is within the above range, each of the etching rate and side etching can be controlled by a combination with other components, but if it is smaller or larger than this, the etching rate is extremely low, Or since it becomes a high state, control becomes difficult.

  The etching solution composition of the present invention contains phosphoric acid. The concentration of phosphoric acid is 0.1 to 80% by weight, preferably 5 to 50% by weight. When phosphoric acid is smaller or larger than the above range, in-plane uniformity is deteriorated, side etching tends to be large, and control with other components alone becomes difficult. Nitric acid and sulfuric acid may contain only one or both. An etching solution containing sulfuric acid is preferable. The concentration in the case of containing both nitric acid and sulfuric acid is 0.1 to 50% by weight in total, and preferably contains 1 to 20% by weight of nitric acid or 1 to 30% by weight of sulfuric acid. When only nitric acid is contained, the concentration of nitric acid is 0.1 to 50% by weight, preferably 1 to 20% by weight. When only sulfuric acid is contained, the concentration of sulfuric acid is 0.1 to 50% by weight, preferably 1 to 30% by weight.

  In one embodiment of the present invention, the etching solution composition of the present invention does not contain nitric acid. Since the composition of the persulfate solution, phosphoric acid and sulfuric acid has more sulfate ions than the composition of the persulfate solution, phosphoric acid and nitric acid, the solution stability of the anion ions of the persulfate can be improved. In addition, when nitric acid is added based on a persulfuric acid solution, the etching rate does not fluctuate. However, the amount of phosphoric acid and sulfuric acid is adjusted to increase the speed when phosphoric acid is added and to reduce the speed when sulfuric acid is added. By doing so, there is an advantage that the etching rate can be easily controlled.

  In one embodiment of the present invention, the etching solution composition of the present invention may contain chloride ions. Chloride ions may be present in the etching solution composition by adding a compound that easily dissolves in water to generate chloride ions or hydrochloric acid. Compounds that produce chloride ions include zinc chloride, zinc ammonium chloride, aluminum chloride, ammonium chloride, cobalt (II) chloride, copper (II) chloride, palladium chloride, isobutyl chloride, isopropyl chloride, indium chloride (III), chloride Ethylene, oleyl chloride, potassium chloride, calcium chloride, silver chloride, chromium chloride (II), cobalt chloride (II), choline chloride, zirconium chloride (IV), mercury chloride (I), tin chloride (IV), tin chloride ( II), tin chloride (VI), strontium chloride, cesium chloride, cerium chloride (III), tungsten chloride (VI), tantalum chloride (V), titanium chloride (IV), titanium chloride (III), iron chloride (II) , Iron (III) chloride, tetraethylammonium chloride, copper (I) chloride, copper (II) chloride, sodium chloride, lead (II) chloride, nickel (II) chloride, Examples of the chloride include platinum (II) chloride, potassium platinum (IV) chloride, barium chloride, palladium (II) chloride, methylene chloride, ethylene chloride, and lithium chloride. In particular, hydrochloric acid is preferable from the viewpoint of solution stability in an acidic solution and wettability to a finely processed portion. Chloride ions have been found to contribute in particular to the dissolution rate of copper alloys, allowing for rate control as well as taper angle control. In addition, since chloride ions have a high moving speed in an aqueous solution and promote uniform dissolution on the surface of the workpiece, in-plane uniformity is improved and side etching is suppressed.

  The concentration of chloride ions can be appropriately set depending on the film type and film thickness of the copper alloy, but is not limited thereto, but is 0.00001 to 30% by weight, preferably 0.00003 to 2% by weight. %, More preferably 0.00003 to 0.05% by weight. When the chloride ion is smaller than the above range, there is almost no effect of improving the in-plane uniformity, and when the chloride ion is larger, the dissolution of the copper alloy is faster than copper, so that the cross-sectional shape tends to deteriorate. Furthermore, a residue that seems to be cuprous chloride is likely to be generated. This is presumably because chlorine and the copper surface react to form hardly soluble cuprous chloride on the copper surface, which inhibits etching. However, the etching liquid composition of the present invention can suppress the formation of cuprous chloride and the generation of residues by adding ammonium ions.

  Ammonium ions may be present in the etching solution composition by adding a compound that dissolves in water and easily generates ammonium ions. Compounds that produce ammonium ions include diammonium hydrogen phosphate, ammonium amidosulfate, ammonium zinc chloride, ammonium chloride, ammonium zinc chloride, ammonium cobalt chloride (II), ammonium copper chloride (II), ammonium palladium chloride (II), chloride Tetraethylammonium chloride, tetrabutylammonium chloride, tetrapropylammonium chloride, hydroxylammonium chloride, ammonium perchlorate, ammonium periodate, ammonium formate, ammonium citrate, ammonium iron (III) citrate, monoammonium citrate, citric acid Triammonium, diammonium hydrogen citrate, iron (III) ammonium citrate, ammonium dihydrogen citrate, ammonium acetate, ammonium ammonium fluoride, tetraborate Ammonium, ammonium bromide, ammonium oxalate, ammonium hydrogen oxalate, ammonium iron (III) oxalate, ammonium tartrate, ammonium nitrate, cerium ammonium nitrate (IV), tetraethylammonium hydroxide, tetrabutylammonium hydroxide, tetrapropylammonium hydroxide , Tetramethylammonium hydroxide, ammonium bicarbonate, ammonium carbonate, ammonium thiosulfate, ammonium trifluoroacetate, ammonium lactate, ammonium hydrogen fluoride, ammonium borate, ammonium iodide, ammonium sulfate, aluminum ammonium sulfate, chromium chromium (III) sulfate, cobalt ammonium sulfate (II), ammonium iron sulfate (II), ammonium iron sulfate (III), copper ammonium sulfate (II) Nickel (II), ammonium magnesium sulfate, ammonium manganese sulfate (II), monoammonium phosphate, triammonium phosphate, sodium ammonium hydrogen phosphate, ammonium dihydrogen phosphate, etc. Ammonium hydrogen and diammonium hydrogen phosphate are preferred. The concentration of ammonium ions can be appropriately set depending on the film type and film thickness of the copper alloy, the concentration of persulfuric acid solution, nitric acid, sulfuric acid, and chloride ions, but is not limited to this. -50% by weight, preferably 1-5% by weight. If the ammonium ion is smaller than the above range, it is difficult to control the generation of residue that occurs when chloride ions are added, and the dissolution rate of the copper alloy is difficult. It tends to get worse.

  Since the dissolution rate of copper and copper alloy can be controlled by adjusting the concentration of chloride ions and ammonium ions, the taper angle can be easily controlled using this. The taper angle is in the range of 20 to 100 degrees, preferably 30 to 60 degrees.

  Furthermore, chloride ions and ammonium ions are more effective in etching a three-layer substrate. That is, in the case of a three-layer substrate, there is a problem that the taper angle becomes smaller than that of a two-layer substrate because the liquid soaks into the resist / copper alloy, but by adding chloride ions and ammonium ions, It is possible to adjust the penetration between the resist / copper alloy and between the copper alloy / glass, and the taper angle of the three-layer substrate can be controlled.

  The etching solution composition of the present invention may further contain one or more surfactants in order to improve the wettability with respect to the surface to be etched. The surfactant is preferably anionic or nonionic.

  By using the etching solution composition of the present invention, etching can be performed safely and with high accuracy by a simple etching process without using a hydrogen peroxide solution or a fluorine compound. Further, unlike the composition using hydrogen peroxide solution, it is not necessary to dissolve copper before substrate processing in order to stabilize the etching rate of copper. Furthermore, since etching can be performed without containing an organic acid, there is no need to consider problems such as resist peeling.

  The etching solution composition of the present invention can also prepare a replenisher solution using a persulfate and / or a persulfate solution, phosphoric acid, nitric acid, sulfuric acid, chloride ions, ammonium ions. Even if only the required amount of persulfuric acid solution is added in accordance with the decrease rate of the liquid, it is possible to extend the liquid life, but in some cases, if other components are added simultaneously, the liquid life is further extended. It becomes possible. Thereby, the use cost can be reduced.

  A further aspect of the present invention is an etching of a metal laminated film having a copper layer and a copper oxide layer and / or a copper alloy layer (excluding copper and molybdenum, copper and titanium, and copper alloys composed of copper and chromium, respectively) A process comprising 0.1 to 80% by weight of a persulfate solution and / or persulfate solution, 0.1 to 80% by weight of phosphoric acid, 0.1 to 50% by weight of nitric acid and / or 0.1 to 0.1% of sulfuric acid. It is related with the said etching method including the process of etching using the etching liquid composition containing 50 weight%.

  According to the etching method of the present invention, since the dissolution rates of copper and copper alloy differ depending on the temperature, the taper angle can be controlled by changing the temperature using this. A preferable temperature is 20 to 80 degrees from the viewpoint of temperature conditions that can be set in the etching apparatus, and a more preferable temperature is 25 to 40 degrees.

  The etching composition and etching method of the present invention exhibit particularly excellent etching characteristics in a laminated film having a new copper alloy, that is, a copper-magnesium-aluminum alloy and / or a copper-magnesium-aluminum oxide alloy. Here, the copper-magnesium-aluminum alloy is preferably formed by sputtering a target material composed of 0.1 to 10.0 atomic% Mg, 0.1 to 10.0 atomic% Al, the remainder Cu and unavoidable impurities. It is an alloy obtained by doing this, and is a Cu alloy film for wiring films. The copper-magnesium-aluminum oxide alloy is an alloy obtained by sputtering the target material under an oxygen partial pressure of 0.1 to 20%. The film made of a copper-magnesium-aluminum oxide alloy does not have a problem that the adhesion deteriorates due to the reduction of the oxide film by the hydrogen plasma treatment performed in the TFT manufacturing process in the flat panel display manufacturing process ( ULVAC TECHNICAL JOUNAL No.71 2009 P24-28).

  In one embodiment of the present invention, the etching solution composition and the etching method of the present invention relate to an etching solution composition and an etching method for etching a driving transistor electrode in a flat panel display.

  The present invention will be described in more detail with reference to the following examples and comparative examples. However, the present invention is not limited to these examples in any way, and may be appropriately modified and implemented without departing from the scope of the present invention. Is possible.

Examples 1 to 53
After forming a Cu alloy (Cu—Mg—Al) having a thickness of 500 mm on a glass substrate and forming a Cu film having a thickness of 3000 mm, a resist pattern is formed. Immersion was performed for 1.5 times the just etching time. Thereafter, washing, drying, and residue were evaluated. For the persulfuric acid solution, LD100 manufactured by DuPont (solution containing KHSO ₅ as a main component) was used.
The results are shown in Tables 1-4. Moreover, the result of the SEM photograph of Tables 1-3 is shown to FIGS. 1-3, respectively.

When the concentration of LD100 (KHSO ₅ ) is fixed, and the cross-sectional shape of the Cu / CuMgAl substrate when the concentration of nitric acid or sulfuric acid and the phosphoric acid concentration are changed, the side etching amount changes depending on the various concentrations. It can be seen that the side etching amount can be suppressed by optimizing each concentration. The side etching amount can be sufficiently utilized if it is 10 times or less the film thickness of the substrate, but it is preferably 7 to 4 times or less, more preferably 3 times or less, and even more preferably 2 times or less. Further, since the etching rate also changes at the same time, the side etching amount and the etching rate can be controlled simultaneously by adjusting the concentrations of phosphoric acid and nitric acid and / or sulfuric acid.

Example 54
A 500 mm thick Cu alloy (Cu-Mg-Al) on a glass substrate, a 3000 mm thick Cu film, and a 300 mm thick Cu alloy (Cu-Mg-Al) on a glass substrate A resist pattern was formed on each of the substrates having a thickness of 4000 mm and immersed in the etching solution shown in Table 5 at a liquid temperature of 30, 40, and 50 ° C. for 1.5 times the just etching time. Thereafter, washing, drying, and residue were evaluated. For the persulfuric acid solution, LD100 manufactured by DuPont (solution containing KHSO ₅ as a main component) was used.
The results are shown in Table 6, and the SEM photograph results in Table 6 are shown in FIG.

  When the cross-sectional shape at the time of changing the liquid temperature was confirmed using two types of substrates having different film thicknesses, it was found that the taper angle increased as the temperature increased. Further, it was confirmed that the range of variation of the taper angle of the Cu (4000 mm) / CuMgAl (300 mm) substrate was wider than that of the Cu (3000 mm) / CuMgAl (500 mm) substrate. The factor that changes the taper angle is that the dissolution rate of Cu and CuMgAl changes, and CuMgAl is particularly highly dependent on the liquid temperature. Further, the film thickness of the substrate is also involved, and the thinner the CuMgAl film, the faster the dissolution from the lower layer, so that the influence on the taper angle becomes larger and the range in which this can be controlled becomes wider.

Examples 55-58
After forming a Cu alloy (Cu—Mg—Al) having a thickness of 500 mm on a glass substrate and forming a Cu film having a thickness of 3000 mm, a resist pattern was formed. Based on the etching liquid of Table 7 and Example 55, The cross-sectional shape and residue when hydrochloric acid was added were evaluated. The liquid temperature was 30 ° C., and the immersion was performed for 1.5 times the just etching time. Further, LD100 (a solution containing KHSO ₅ as a main component) manufactured by DuPont was used as the persulfuric acid solution.
The results are shown in Table 8, and the SEM photograph results in Table 8 are shown in FIG.

  When the cross-sectional shape at the time of changing the hydrochloric acid concentration was confirmed based on the composition of Example 55, it was found that the taper angle increased as the concentration increased. It was also found that the amount of side etching can be suppressed as the hydrochloric acid concentration increases.

  This is because chloride ions are more reactive with CuMgAl than Cu, thereby enabling control of the taper angle or cross-sectional shape. In addition, since chloride ions move at a high speed in an aqueous solution and promote uniform dissolution of the workpiece surface, in-plane uniformity is improved, and side etching can be suppressed.

Examples 59-62
A Cu alloy (Cu-Mg-Al) having a thickness of 500 mm, a Cu alloy having a thickness of 3000 mm, and a Cu alloy (Cu-Mg-Al) having a thickness of 500 mm are formed on a glass substrate, and then a resist pattern is formed. Then, using the etching solution of Table 9 and Example 59 as a base, the cross-sectional shape and the residue when hydrochloric acid was added were evaluated. In addition, diammonium hydrogen phosphate was added together with hydrochloric acid for evaluation. The liquid temperature was 30 ° C., and the immersion was performed for 1.5 times the just etching time. Further, LD100 (a solution containing KHSO ₅ as a main component) manufactured by DuPont was used as the persulfuric acid solution.
The results are shown in Table 10, and the SEM photograph results in Table 10 are shown in FIG.

Examples 63-66
A Cu alloy (Cu-Mg-Al) having a thickness of 500 mm, a Cu alloy having a thickness of 3000 mm, and a Cu alloy (Cu-Mg-Al) having a thickness of 500 mm are formed on a glass substrate, and then a resist pattern is formed. Then, based on the etching solution of Table 11 and Example 63, the cross-sectional shape and the residue when hydrochloric acid was added were evaluated. In addition, diammonium hydrogen phosphate was added together with hydrochloric acid for evaluation. The liquid temperature was 30 ° C., and the immersion was performed for 1.5 times the just etching time. Further, LD100 (a solution containing KHSO ₅ as a main component) manufactured by DuPont was used as the persulfuric acid solution.
The results are shown in Table 12, and the results of the SEM photograph of Table 12 are shown in FIG.

  A three-layer (CuMgAl / Cu / CuMgAl) substrate tends to have a smaller taper angle than a two-layer (Cu / CuMgAl) substrate. Therefore, etching with a small amount of side etching and maintaining a forward taper is possible, but it is difficult to accurately control the taper angle only by the addition concentration of hydrochloric acid. Although it is possible to change the cross-sectional shape by increasing the hydrochloric acid concentration to some extent, if the hydrochloric acid concentration is too high, a residue that appears to be cuprous chloride tends to be generated on the substrate surface. On the other hand, when the concentrations of hydrochloric acid and diammonium hydrogen phosphate are controlled to be added, the generation of residues is suppressed, etching with a large taper angle is possible while maintaining the forward taper, and the taper angle can be controlled. Admitted.

Example 67 and Comparative Example 1
After forming a Cu alloy (Cu—Mg—Al) having a thickness of 500 mm on a glass substrate and forming a Cu film having a thickness of 3000 mm, a resist pattern is formed, and etching evaluation is performed using the etching solution shown in Table 13. It was. Two test methods were used: a dip test in which the substrate is immersed in a beaker for etching, and a spray test in which the substrate is etched by spraying an etching solution in a mist form. Both liquid temperatures were processed at 30 ° C. for 1.5 times the just etching time, and then washed with water, dried, and evaluated for residues. For the persulfuric acid solution, LD100 manufactured by DuPont (solution containing KHSO ₅ as a main component) was used.
The results are shown in Table 14, and the SEM photograph results in Table 14 are shown in FIG.

  Using Example 67 containing persulfate, phosphoric acid and sulfuric acid, and Comparative Example 1 of the phosphoric acid + nitric acid + acetic acid system, evaluation by a dip test and a spray test was performed. In the dip test, the cross-sectional shape is forward-tapered and no residue is obtained with either composition, but in the spray test, only the comparative example 1 has a cross-sectional shape that is tapered at both ends, a shape similar to the tip of an arrow. (Denoted as arrow shape).

  This is considered to be due to the difference in dissolution performance between the two liquids. In the etching solution of the present invention containing persulfate, phosphoric acid and sulfuric acid, the etching rate of Cu increases as the stirring speed increases in the beaker test. However, in the phosphoric acid + nitric acid + acetic acid system, the stirring speed increases. Accordingly, the etching rate of Cu tends to decrease. Since the stirring speed of the beaker test shows the same tendency as the flow rate of the spray test, in the phosphoric acid + nitric acid + acetic acid system, the etching rate decreases as the spray flow rate increases. Further, the flow rate of the spray test is harder to control than the stirring speed of the beaker test, and the flow rate tends to increase (is difficult to decrease).

  Therefore, in the composition of Comparative Example 1, dissolution hardly progresses only by spraying. The sprayed liquid can be dissolved by accumulating on the substrate, but the etching rate of the liquid that accumulates on this substrate is higher than the etching rate of the spray spray, so the lower layer that is in contact with the accumulated liquid dissolves in the upper layer. It is estimated that the cross-sectional shape becomes an arrow shape.

  In addition, the spray test of Comparative Example 1 has a problem that a residue is likely to be generated at the end of the substrate. Even if the flow rate of the spray device can be set finely, it is difficult to use because the control range is narrow. Compared to this, the composition used in the examples does not require fine conditions in both the dip test and the spray test, and can be prepared with a good cross-sectional shape and no residue.

Claims (14)

Etching solution composition for etching a metal laminated film having a copper layer and a copper oxide layer and / or a copper alloy layer (excluding copper alloys composed of copper and molybdenum, copper and titanium, and copper and chromium) Because
The etching solution comprising a persulfate solution and / or a persulfate solution 0.1 to 80% by weight, phosphoric acid 0.1 to 80% by weight, and nitric acid and / or sulfuric acid 0.1 to 50% by weight Composition. The persulfate solution is an aqueous solution containing one or more kinds of potassium peroxomonosulfate, potassium hydrogen peroxysulfate (KHSO ₅ ), ammonium peroxodisulfate or potassium peroxodisulfate. Etching solution composition. The etching solution composition according to claim 1, wherein the persulfate solution and / or the persulfate solution contains potassium peroxysulfate (KHSO ₅ ).   The persulfuric acid solution contains one or more kinds of potassium peroxomonosulfate, ammonium peroxodisulfate, and potassium peroxodisulfate, and the active oxygen is 0.01 to 5% by weight. The etching liquid composition as described in any one of these.   The etching liquid composition as described in any one of Claims 1-4 which does not contain nitric acid.   Furthermore, 0.00001-30 weight% of chloride ions are contained, The etching liquid composition as described in any one of Claims 1-5 characterized by the above-mentioned.   Furthermore, 0.1-50 weight% of ammonium ions are contained, The etching liquid composition as described in any one of Claims 1-6 characterized by the above-mentioned.   The etching liquid composition according to any one of claims 1 to 7, wherein the metal laminated film has a layer configuration of copper / copper alloy or copper alloy / copper / copper alloy, and the copper alloy is in contact with the substrate. .   The etching liquid composition according to any one of claims 1 to 8, wherein the copper alloy is copper-magnesium-aluminum or copper-magnesium-aluminum oxide.   The etching liquid composition according to any one of claims 1 to 9 for etching a drive transistor electrode in a flat panel display.   A method for etching a metal laminated film having a copper layer and a copper oxide layer and / or a copper alloy layer (excluding copper alloys composed of copper and molybdenum, copper and titanium, and copper and chromium, respectively), The said etching method including the process of etching using the etching liquid composition as described in any one of 1-10.   The etching method according to claim 11, wherein the metal laminated film has a layer configuration of copper / copper alloy or copper alloy / copper / copper alloy, and the copper alloy is in contact with the substrate.   The etching method according to claim 11 or 12, wherein the copper alloy is copper-magnesium-aluminum or copper-magnesium-aluminum oxide.   The etching method according to claim 11, wherein the driving transistor electrode is etched in a flat panel display.