Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F1/00—Etching metallic material by chemical means
  • C23F1/10—Etching compositions
  • C23F1/14—Aqueous compositions
  • C23F1/32—Alkaline compositions
  • C23F1/40—Alkaline compositions for etching other metallic material
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F1/00—Etching metallic material by chemical means
  • C23F1/10—Etching compositions
  • C23F1/14—Aqueous compositions
  • C23F1/16—Acidic compositions
  • C23F1/30—Acidic compositions for etching other metallic material
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P50/00—Etching of wafers, substrates or parts of devices
  • H10P50/60—Wet etching
  • H10P50/66—Wet etching of conductive or resistive materials
  • H10P50/663—Wet etching of conductive or resistive materials by chemical means only
  • H10P50/667—Wet etching of conductive or resistive materials by chemical means only by liquid etching only
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P50/00—Etching of wafers, substrates or parts of devices
  • H10P50/60—Wet etching
  • H10P50/64—Wet etching of semiconductor materials
  • H10P50/642—Chemical etching

Definitions

• the present invention relates to a processing liquid for etching ruthenium of a semiconductor wafer containing ruthenium in a process of manufacturing a semiconductor element.
• the design rules for semiconductor devices have become finer, and wiring resistance tends to increase.
• the increase in wiring resistance it has become remarkable that the high-speed operation of the semiconductor element is hindered, and countermeasures are required. Therefore, as the wiring material, a wiring material having an electromigration resistance and a reduced resistance value is desired as compared with the conventional wiring material.
• ruthenium Compared to conventional wiring materials such as aluminum and copper, ruthenium has high electromigration resistance and can reduce the resistance value of wiring, so it is particularly noteworthy as a wiring material with a semiconductor element design rule of 10 nm or less. Has been done. In addition to wiring materials, ruthenium can prevent electromigration even when copper is used as the wiring material, so it is also being considered to use ruthenium as a barrier metal for copper wiring. ..
• the wiring is formed by dry or wet etching as in the conventional wiring material.
• dry etching with an etching gas, etching with CMP polishing, and removal of ruthenium, more precise etching is desired, and specifically, wet etching is attracting attention.
• the dissolution rate of ruthenium that is, the etching rate is important. If the etching rate is high, ruthenium can be melted in a short time, so that the number of wafers processed per unit time can be increased.
• RuO 4 - or RuO 4 2- is changed to RuO 4 in the processing solution, part of it is released into the gas phase is gasified. Since RuO 4 is strongly oxidizing, it is not only harmful to the human body, but is also easily reduced to produce RuO 2 particles. In general, particles cause a decrease in yield, which is a great problem in the semiconductor forming process. against this background, possible to suppress the generation of RuO 4 gas is extremely important.
• Patent Document 1 contains hypochlorite ion and a solvent, and has a pH of more than 7 and less than 12.0 at 25 ° C.
• a processing liquid for wafers having the above has been proposed. It has been shown that the liquid contains hypochlorite ions and can remove ruthenium and tungsten adhering to the end face portion and the back surface portion of the semiconductor wafer.
• Patent Document 2 a bromine-containing compound, an oxidizing agent, a basic compound and water are added and mixed, and the amount of the bromine-containing compound added is 2 to 25% by mass as the amount of bromine element with respect to the total mass, and the oxidizing agent.
• Described is an etching composition of a ruthenium-based metal, characterized in that the amount of the compound added is 0.1 to 12% by mass and the pH is 10 or more and less than 12.
• Patent Document 1 describes a treatment liquid having a pH of more than 7 and less than 12.0 as a treatment liquid for a wafer containing ruthenium.
• the etching rate of ruthenium is sufficient, but RuO 4 gas is not mentioned, and the method described in Patent Document 1 does not actually suppress the generation of RuO 4 gas. I could not do it. That is, in the processing solution of a wafer having a ruthenium described in Patent Document 1, it has been difficult to achieve both the etch rate and RuO 4 gas control ruthenium.
• Etching composition of ruthenium containing metal disclosed in Patent Document 2 although and less than pH10 than 12, in this pH range for RuO 4 gas with the etching of ruthenium occurs, there is room for improvement It was. Further, Patent Document 2 does not mention suppression of RuO 4 gas, and the method described in Patent Document 2 could not actually suppress the generation of RuO 4 gas. Further, the etching composition has a problem that the chemical stability is poor and the etching rate of ruthenium fluctuates greatly with the passage of time. Further, as a method for preparing the treatment liquid, a method of appropriately adjusting the pH by mixing a base compound with an oxide obtained by oxidizing a bromine-containing compound with an oxidizing agent under acidic conditions is shown.
• the present invention has been made in view of the above background technology, and an object of the present invention is that ruthenium adhering to the front surface, end face portion and back surface portion of a semiconductor wafer can be etched at a sufficient speed, and the stability of the speed is excellent. Further, it is an object of the present invention to provide a treatment liquid capable of suppressing the generation of RuO 4 gas and a method for producing the treatment liquid.
• the present inventors have conducted diligent studies to solve the above problems. Then, they found that ruthenium can be etched at high speed by treating ruthenium with a treatment liquid containing hypobromous acid ion. Furthermore, it has been found that the bromine-containing compound added to the alkaline treatment liquid is oxidized by the oxidizing agent in the treatment liquid to become a bromine oxide, so that ruthenium can be etched at a higher speed. Further, suitable pH ranges, by a bromine-containing compound concentration range and oxidant concentration range, is stabilized at a sufficient etching rate, and found to be able to suppress the RuO 4 gas generation, which resulted in the completion of the present invention ..
• the configuration of the present invention is as follows.
• Item 1 A processing solution for ruthenium semiconductors containing hypobromous acid ions.
• Item 2 The semiconductor treatment liquid according to Item 1, wherein the hypobromous acid ion is 0.001 mol / L or more and 0.20 mol / L or less.
• Item 3 The semiconductor treatment liquid according to Item 1 or 2, wherein the hypobromous acid ion is 0.01 mol / L or more and 0.10 mol / L or less.
• Item 4 Item 1 to item 1 to 3, wherein the treatment liquid for semiconductor further contains an oxidizing agent, and the redox potential of the oxidizing agent exceeds the redox potential of the hypobromous acid ion / Br ⁇ system.
• Item 5 The semiconductor processing solution according to Item 4, wherein the oxidizing agent contained in the semiconductor processing solution is hypochlorite ion or ozone.
• Item 6 The semiconductor treatment liquid according to any one of Items 1 to 5, further containing tetraalkylammonium ions.
• Item 7 The semiconductor treatment liquid according to Item 6, wherein the tetraalkylammonium ion is tetramethylammonium ion.
• Item 8 The semiconductor treatment liquid according to any one of Items 1 to 7, wherein the ratio of the hypobromous acid ion in 1 mol of the bromine element contained in the semiconductor treatment liquid exceeds 0.5 mol.
• Item 9 The semiconductor treatment liquid according to any one of Items 1 to 8, wherein the pH of the treatment liquid is 8 or more and 14 or less.
• Item 10 The semiconductor treatment liquid according to any one of Items 1 to 9, wherein the pH of the treatment liquid is 12 or more and less than 13.
• Item 11 At least a bromine-containing compound, an oxidizing agent, a basic compound and water, and the amount of the bromine-containing compound added is 0.008% by mass or more and less than 10% by mass as the amount of bromine element with respect to the total mass of the oxidizing agent.
• a treatment liquid for semiconductors of ruthenium having an addition amount of 0.1% by mass or more and 10% by mass or less and a pH of 8 or more and 14 or less.
• Item 12 The ruthenium semiconductor treatment liquid according to Item 11, wherein the amount of the bromine-containing compound added is 0.08% by mass or more and less than 2.0% by mass as the amount of bromine element.
• Item 13 Item 11 or 12 wherein the amount of the bromine-containing compound added is 0.01% by mass or more and less than 2% by mass as the amount of bromine element, and the amount of the oxidizing agent added is 0.1% by mass or more and 10% by mass or less.
• Item 14 The semiconductor treatment liquid according to any one of Items 11 to 13, wherein the ruthenium is a ruthenium-based metal or a ruthenium alloy.
• Item 15 The semiconductor treatment liquid according to any one of Items 11 to 14, wherein the oxidizing agent is a hypochlorous acid compound or ozone.
• Item 16 The treatment liquid for a semiconductor according to any one of Items 11 to 15, wherein the bromine-containing compound is a bromate salt or hydrogen bromide.
• Item 17 The treatment liquid for semiconductors according to Item 16, wherein the bromate is tetraalkylammonium bromide.
• Item 18 The treatment liquid for semiconductors according to Item 17, wherein the tetraalkylammonium bromide is tetramethylammonium bromide.
• Item 19 The treatment liquid for a semiconductor according to any one of Items 11 to 18, wherein the base compound is tetramethylammonium hydroxide.
• Item 20 The semiconductor processing solution according to any one of Items 11 to 19, wherein the pH is 12 or more and 14 or less.
• Item 21 The semiconductor processing solution according to any one of Items 11 to 20, wherein the pH is 12 or more and less than 13.
• Item 22 The semiconductor treatment liquid according to Item 14, wherein the ruthenium-based metal contains 70 atomic% or more of ruthenium.
• Item 23 The processing liquid for a semiconductor according to Item 14, wherein the ruthenium-based metal is metallic ruthenium.
• Item 24 The semiconductor treatment liquid according to Item 14, wherein the ruthenium alloy contains 70 atomic% or more and 99.99 atomic% or less of ruthenium.
• Item 25 The semiconductor treatment liquid according to any one of Items 11 to 24, wherein the ratio of the hypobromous acid ion in 1 mol of the bromine element contained in the semiconductor treatment liquid exceeds 0.5 mol.
• Item 26 The method for producing a treatment liquid for a semiconductor according to any one of Items 11 to 25, which comprises a step of mixing the solution containing the oxidizing agent and the base compound with the bromine-containing compound.
• Item 27 The method for producing a processing liquid for a semiconductor according to any one of Items 11 to 25, which comprises a step of mixing the bromine-containing compound with an aqueous solution of the oxidizing agent and the base compound.
• Item 28 A method for treating a substrate in which a processing liquid for a semiconductor is produced by the production method according to Item 26 or 27, and then the ruthenium-based metal film and / or a ruthenium alloy film deposited on the substrate is etched with the processing liquid for a semiconductor.
• a method for producing a treatment liquid for a semiconductor of ruthenium which comprises a step of mixing a solution containing a basic compound with hypobromous acid, hypobromous acid, bromate water, or bromine gas.
• Item 30 A method for producing a ruthenium semiconductor treatment liquid, which comprises a step of mixing a solution containing a hypochlorous acid compound and a base compound with a bromine-containing compound.
• Item 31 In the step of mixing the solution containing the hypochlorous acid compound and the base compound and the bromine-containing compound, the bromine-containing compound is added to the solution containing the hypochlorite compound and the base compound.
• Item 3 The method for producing a processing solution for a semiconductor, which is a step of mixing.
• Item 32 The method for producing a semiconductor processing solution according to any one of Items 29 to 31, wherein the solution is an aqueous solution.
• Item 33 The production method according to any one of Items 29 to 32, wherein the ruthenium is a ruthenium-based metal or a ruthenium alloy.
• Item 34 The method for producing a treatment liquid for a semiconductor according to any one of Items 29 to 33, wherein the base compound is tetramethylammonium hydroxide.
• Item 35 The method for producing a treatment liquid for a semiconductor according to any one of Items 30 to 34, wherein the bromine-containing compound is a bromate salt or hydrogen bromide.
• Item 36 The method for producing a processing liquid for a semiconductor according to Item 35, wherein the bromate is onium bromide.
• Item 37 The method for producing a processing liquid for a semiconductor according to Item 36, wherein the onium bromide is a quaternary onium bromide or a tertiary onium bromide.
• Item 38 The method for producing a semiconductor treatment liquid according to Item 37, wherein the quaternary onium bromide is tetraalkylammonium bromide.
• Item 39 The method for producing a treatment liquid for a semiconductor according to Item 38, wherein the tetraalkylammonium bromide is produced from tetraalkylammonium hydroxide and bromide ions.
• Item 40 The method for producing a treatment liquid for a semiconductor according to Item 38 or 39, wherein the tetraalkylammonium bromide is produced from tetraalkylammonium hydroxide and hydrogen bromide.
• Item 41 The method for producing a processing liquid for a semiconductor according to Item 35, wherein the bromate is ammonium bromide, sodium bromide, or potassium bromide.
• Item 42 The method for producing a treatment liquid for a semiconductor according to any one of Items 30 to 41, wherein the solution containing the hypochlorous acid compound is a tetraalkylammonium hypochlorous acid solution.
• the step of producing the tetraalkylammonium hypochlorite solution includes a preparatory step of preparing the tetraalkylammonium hydroxide solution and a reaction step of bringing the tetraalkylammonium hydroxide solution into contact with chlorine, and reacts.
• Item 4 The method for producing a treatment liquid for semiconductors according to Item 42, wherein the carbon dioxide concentration of the gas phase portion in the step is 100 volume ppm or less, and the pH of the liquid phase portion in the reaction step is 10.5 or more.
• Item 44 The method for producing a treatment liquid for a semiconductor according to Item 43, wherein the tetraalkylammonium hydroxide prepared in the preparation step has an alkyl group having 1 to 10 carbon atoms.
• Item 45 The method for producing a processing liquid for a semiconductor according to Item 43 or 44, wherein the reaction temperature in the reaction step is ⁇ 35 ° C. or higher and 25 ° C. or lower.
• Item 46 The method for producing a semiconductor treatment liquid according to any one of Items 43 to 45, wherein the carbon dioxide concentration in the tetraalkylammonium hydroxide solution in the reaction step is 0.001 ppm or more and 500 ppm or less.
• ruthenium in a semiconductor forming step, can be stably wet etching at a sufficiently fast rate, further, it is possible to suppress the RuO 4 gas generation. This not only improves the wafer processing efficiency per unit time, but also suppresses the decrease in yield due to RuO 2 particles, enables safe processing for the human body, and achieves both manufacturing cost and safety. ..
• the bromine-containing composition is directly oxidized by an oxidizing agent in an alkaline treatment liquid, and bromine, hypobromous acid, hypobromous acid ion, bromic acid, bromic acid. Ions, bromic acid, bromate ion, perbromic acid, and perbromate ion can be rapidly produced. Since the treatment liquid produced in this way contains hypobromous acid ions, ruthenium can be immediately etched without waiting for the generation of bromine gas for a long time, and the time required for semiconductor production can be shortened.
• the amount of the base compound added to the treatment liquid can be significantly reduced, and the handling of the treatment liquid becomes easy.
• the treatment liquid of the present invention is a treatment liquid containing hypobromous acid ion (BrO ⁇ ).
• Hypobromous acid ion is an oxidizing agent having strong oxidizing property, and the treatment liquid of the present invention containing hypobromous acid ion can etch ruthenium at high speed under alkaline conditions.
• pH by appropriately selecting the type and concentration of the oxidizing agent while suppressing RuO 4 gas generation is a processing liquid ruthenium can be etched at a stable etch rate.
• the treatment liquid of the present invention is a treatment liquid that can be suitably used in an etching step, a residue removing step, a cleaning step, a CMP step, and the like in a semiconductor manufacturing step.
• a ruthenium semiconductor means a semiconductor containing ruthenium.
• a sufficient etching rate in the present invention means an etching rate of 10 ⁇ / min or more.
• the etching rate of ruthenium is 10 ⁇ / min or more, it can be suitably used in an etching step, a residue removing step, a cleaning step, a CMP step and the like.
• RuO 4 gas amount generated when etching the ruthenium is dependent upon the processing conditions (e.g., amount of dissolved ruthenium, the volume of processing solution used, the treatment temperature, volume and material of the container or chamber, etc.) .. Therefore, when comparing the RuO 4 gas generation amount is to be performed in consideration of these conditions is important, in simplified, can be evaluated as emission per unit area of the wafer containing ruthenium.
• processing conditions e.g., amount of dissolved ruthenium, the volume of processing solution used, the treatment temperature, volume and material of the container or chamber, etc.
• the RuO 4 gas suitable absorbent solution generated by the etching e.g., an alkaline solution such as aqueous NaOH
• the amount of RuO 4 generated per unit area of the wafer to be generated can be obtained. Therefore, to check the RuO 4 gas inhibitory effect may be compared to RuO 4 gas generation amount per unit area.
• a treatment liquid having a low amount of RuO 4 generated per unit area suppresses the generation of RuO 4 gas and can suppress the generation of RuO 2 particles, so that it can be suitably used for etching ruthenium.
• the treatment liquid in the present invention can etch ruthenium, but does not etch metals such as copper, cobalt, titanium, platinum, titanium nitride, and tantalum nitride, or the etching rate is extremely low compared to ruthenium-based metals. Therefore, in the semiconductor manufacturing process or the like, it is possible to selectively etch the ruthenium-based metal without damaging the substrate material containing these metals.
• the stable etching rate of ruthenium means that the etching rate of ruthenium by the treatment liquid containing hypobromous acid ion does not change with time. Specifically, when a plurality of wafers having ruthenium (the number of wafers is n) are etched using the same treatment liquid, the etching rate of ruthenium in the first wafer and the etching rate of ruthenium in the nth wafer This means that the etching rates of ruthenium are substantially the same.
• the fluctuation range of the ruthenium etching rate on the nth wafer that is, the increase / decrease in the etching rate is ⁇ 20% with respect to the ruthenium etching rate on the first wafer. It means that it is within.
• the time during which the ruthenium etching rate on the nth wafer increases or decreases within ⁇ 20% with respect to the ruthenium etching rate on the first wafer is defined as the etching rate stabilization time.
• a suitable value for the stabilization time of the etching rate varies depending on the conditions in which the treatment liquid of the present invention is used and the manufacturing process.
• a treatment liquid having a stabilization time of the etching rate of 1 hour or more is suitable for the semiconductor manufacturing process. Can be used for. Considering that there is a time margin for handling the treatment liquid and that the process time can be set flexibly, it is more preferable that the treatment liquid has an etching rate stabilization time of 10 hours or more.
• a treatment liquid in which the etching rate of ruthenium does not change over time or a treatment liquid having a long stabilization time of the etching rate enables stable etching of ruthenium using the treatment liquid in the semiconductor manufacturing process. Not only that, the treatment liquid can be reused, so that the treatment liquid is excellent in terms of productivity and cost.
• the hypobromous acid ion contained in the treatment liquid of the present invention may be generated in the treatment liquid or may be added to the treatment liquid as hypobromous acid salt.
• the hypobromous acid salt referred to here is a salt containing hypobromous acid ion or a solution containing the salt.
• bromine gas may be blown into the treatment liquid.
• the temperature of the treatment liquid is preferably 50 ° C. or lower from the viewpoint of efficiently generating hypobromous acid ions.
• the treatment liquid is 50 ° C. or lower, not only hypobromous acid ions can be efficiently generated, but also the generated hypobromous acid ions can be stably used for ruthenium etching.
• the temperature of the treatment liquid is more preferably 30 ° C. or lower, and most preferably 25 ° C. or lower.
• the lower limit of the temperature of the treatment liquid is not particularly limited, but it is preferable that the treatment liquid does not freeze. Therefore, the treatment liquid is preferably ⁇ 35 ° C. or higher, more preferably ⁇ 15 ° C. or higher, and most preferably 0 ° C. or higher.
• the pH of the treatment liquid into which the bromine gas is blown is not particularly limited, but if the pH of the treatment liquid is alkaline, it can be subjected to ruthenium etching immediately after the formation of hypobromous acid ions.
• hypobromous acid ions are generated by blowing bromine gas into the treatment liquid
• the treatment liquid contains bromide ions (Br ⁇ )
• the solubility of the bromine gas (Br 2) is improved. This is because Br 2 dissolved in the treatment liquid reacts with Br ⁇ and Br 3 ⁇ to form complex ions such as Br 3 ⁇ and Br 5 ⁇ , which are stabilized in the treatment liquid.
• hypobromous acid ions in the treatment liquid by oxidizing the bromine-containing compound with an oxidizing agent.
• hypobromous acid ion as a compound to the treatment solution, hypobromous acid, bromine water, and / or hypobromous acid may be added.
• hypobromous acid sodium hypobromous acid, potassium hypobromous acid, and tetraalkylammonium hypobromous acid are suitable, and hypobromous acid does not contain metal ions, which is a problem in semiconductor production. Acid or tetraalkylammonium hypobromite is more preferred.
• the tetraalkylammonium hypobromite can be easily obtained by passing bromine gas through a tetraalkylammonium hydroxide solution. It can also be obtained by mixing hypobromous acid and a tetraalkylammonium hydroxide solution. Further, tetraalkylammonium hypobromite can also be obtained by substituting a cation contained in hypobromous acid such as sodium hypobromite with tetraalkylammonium ion using an ion exchange resin.
• the concentration of the hypobromous acid ion in the treatment liquid of the present invention is not particularly limited as long as it does not deviate from the object of the present invention, but preferably, the amount of bromine element contained in the hypobromous acid ion is 0. It is 001 mol / L or more and 0.20 mol / L or less. If it is less than 0.001 mol / L, the ruthenium etching rate is low and the practicality is low. On the other hand, when it exceeds 0.20 mol / L, decomposition of hypobromous acid ion is likely to occur, so that the etching rate of ruthenium becomes difficult to stabilize.
• the concentration of the hypobromous acid ion should be 0.001 mol / L or more and 0.20 mol / L or less as the amount of bromine element contained in the hypobromous acid ion. It is preferably 0.005 mol / L or more and 0.20 mol / L or less, and more preferably 0.01 mol / L or more and 0.10 mol / L or less.
• the ratio of hypobromous acid ion in 1 mol of bromine element contained in the treatment liquid exceeds 0.5 mol.
• hypobromous acid ion is easily changed to Br ⁇ by the oxidation reaction and decomposition reaction of ruthenium.
• Br - because no etching of ruthenium, Br in the processing liquid - is oxidized into rapidly hypobromite ions, chemical species having a high ruthenium etching ability (hypobromite ion; BrO -) concentrations of Keeping high is important for stable ruthenium etching.
• the ratio of hypobromous acid ion in 1 mol of bromine element contained in the treatment liquid of the present invention exceeds 0.5 mol, that is, more than half of the total bromine elements in the treatment liquid contain more than half of the bromine elements.
• the concentration of chemical species capable of ruthenium etching can be considered to be sufficiently high, and the ruthenium etching rate is stabilized.
• the concentration of hypobromous acid ion in the treatment liquid can be confirmed by using a widely known method. For example, if the ultraviolet-visible absorptiometry is used, absorption due to hypobromous acid ions can be easily confirmed, and its absorption peak (depending on the pH of the treatment solution, hypobromous acid ion concentration, etc., but approximately around 330 nm).
• the hypobromous acid ion concentration can be obtained from the intensity of.
• the hypobromous acid ion concentration can also be determined by iodine titration.
• the hypobromous acid ion concentration can be determined from the redox potential (ORP) and pH of the treatment liquid.
• the measurement by the ultraviolet-visible absorptiometry is most preferable.
• the hypobromous acid ion concentration by the ultraviolet-visible absorptiometry if there is absorption by other chemical species, perform data processing such as spectrum division and baseline correction, and select an appropriate reference. Therefore, the hypobromous acid ion concentration can be obtained with sufficient accuracy.
• HBrO and BrO processing solution - if it contains, HBrO and BrO - the total concentration of may be handled as the concentration of the hypobromite ion.
• hypobromous acid ion dissolves ruthenium The details of the mechanism by which hypobromous acid ion dissolves ruthenium are not always clear, but hypobromous acid or hypobromous acid generated from hypobromous acid ion in the treatment solution oxidizes ruthenium, and RuO 4 , RuO 4 - or speculate that dissolved in the processing solution by a RuO 4 2-. Ruthenium RuO 4 - to dissolve or as RuO 4 2-, to reduce the generation amount of RuO 4 gas, it is possible to suppress the occurrence of RuO 2 particles.
• Ruthenium RuO 4 - to dissolve or as RuO 4 2- is preferably pH of the processing solution is alkaline, more preferably a pH of the processing liquid is 8 to 14, pH 12 or more 14 It is more preferably less than or equal to, and most preferably the pH is 12 or more and less than 13. If it is less than the processing liquid having a pH of 12 or more 13, ruthenium RuO 4 - to dissolve or treatment solution RuO 4 as 2, the generation amount of RuO 4 gas to significantly reduce the occurrence of RuO 2 particles It can be suppressed.
• Acid or alkali can be added to the treatment solution to adjust the pH of the treatment solution.
• the acid may be either an inorganic acid or an organic acid, and for example, carboxylic acids such as hydrofluoric acid, hydrochloric acid, hydrobromic acid, nitrate, acetic acid, sulfuric acid, peroxodisulfate, formic acid and acetic acid.
• carboxylic acids such as hydrofluoric acid, hydrochloric acid, hydrobromic acid, nitrate, acetic acid, sulfuric acid, peroxodisulfate, formic acid and acetic acid.
• a widely known acid used in a treatment liquid for semiconductors can be used without any limitation.
• As the alkali it is preferable to use an organic alkali because it does not contain metal ions, which is a problem in semiconductor production.
• an organic alkali is tetraalkylammonium hydroxide, which is composed of tetraalkylammonium ions and hydroxide ions.
• examples of the tetraalkylammonium hydroxide include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide and the like.
• the organic alkali is preferably tetraalkylammonium hydroxide, and is tetramethylammonium hydroxide. Is more preferable.
• the tetraalkylammonium ion contained in the treatment liquid may be used alone or in combination of two or more.
• the treatment liquid of the present invention preferably contains an oxidizing agent.
• the oxidizing agent When the oxidizing agent is contained in the treatment liquid of the present invention, it plays a role of reoxidizing the bromide ion (Br ⁇ ) generated by the decomposition of hypobromous acid ion to hypobromous acid ion.
• hypobromous acid ion When oxidizing the ruthenium, hypobromite ions Br - it is reduced to.
• hypobromous acid ion is easily spontaneously decomposed in the treatment liquid, and a part of it changes to Br ⁇ .
• the decomposition of hypobromous acid ion is promoted by ultraviolet rays and visible light, and a part of the hypobromous acid ion is changed to Br ⁇ .
• hypobromous acid ion is decomposed by heating, contact with acid, and contact with metal, and a part of hypobromous acid ion is changed to Br ⁇ .
• the etching rate of ruthenium decreases as the reduction or decomposition of hypobromous acid ion proceeds.
• an appropriate oxidizing agent is contained in the treatment liquid, Br ⁇ generated by reduction or decomposition can be oxidized to hypobromous acid ion, and the decrease in ruthenium etching rate can be moderated. That is, when hypobromous acid ion and an appropriate oxidizing agent are contained in the treatment liquid, the stabilization time of the etching rate becomes long.
• the redox potential between the oxidizing agent and the chemical species generated by the reduction of the oxidizing agent may exceed the redox potential of the hypobromous acid ion / Br ⁇ system.
• the use of such an oxidizing agent, Br - can the be oxidized to hypobromite ion.
• the oxidation-reduction potential between the oxidant that may be contained in the treatment liquid / the chemical species generated by the reduction of the oxidant is the concentration of the oxidant and the chemical species generated by the reduction of the oxidant, the temperature and pH of the solution. varies depending etc., regardless of these conditions, redox potential between the chemical species generated oxidizing agent / oxidizing agent and reduction, hypobromite ion / Br - exceeds the system redox potential Just do it.
• the upper limit of the redox potential of the oxidizing agent that may be contained in the treatment liquid between the oxidizing agent and the chemical species generated by the reduction of the oxidizing agent is particularly limited as long as the object of the present invention is not deviated. There is no.
• the redox potential is RuO 4 - If / RuO 4 system higher than the oxidation-reduction potential (1.0 V vs. SHE) of, RuO 4 dissolved in the processing liquid - is oxidized to RuO 4 with an oxidizing agent, RuO 4 gas generation may increase. In such cases, and the amount of oxidizing agent added to the processing solution, by appropriately adjusting the timing of adding the oxidizing agent, RuO 4 - suppressing oxidation of RuO 4 from controlling the RuO 4 gas generation amount Is possible.
• hypochlorite ion Since the oxidizing agent that may be contained in the treatment liquid of the present invention does not contain a metal element that causes a problem in semiconductor manufacturing, it is preferable to use hypochlorite ion or ozone. Among them, hypochlorite ion is more preferable in that it has high solubility in a treatment solution, stably exists in the solution, and its concentration can be easily adjusted.
• Hypochlorite ion and ozone have the ability to reoxidize Br ⁇ to hypobromous acid ion in an alkaline treatment liquid (pH 8 or more and 14 or less).
• This hypochlorite / Cl - oxidation-reduction potential of the system is 0.89 V, the oxidation-reduction potential of the ozone / oxygen system whereas a 1.24V, hypobromite ion / Br - oxidation system It can be seen from the fact that the reduction potential is 0.76 V.
• the redox potential is a value with respect to a standard hydrogen electrode at pH 14 (25 ° C.).
• the treatment solution of the present invention containing hypobromous acid ion and hypochlorite ion or ozone increases the concentration of hypobromous acid ion in the treatment solution by oxidizing Br ⁇ to hypobromous acid ion. Since the concentration can be maintained, it is possible to stabilize the etching rate of ruthenium.
• Table 8 shows an example in which hypochlorite ion was used as the oxidizing agent. It can be seen that the redox potential of the hypochlorite ion / Cl - based system is higher than that of the hypobromous acid ion / Br -based system at any pH.
• the treatment liquid of the present invention containing both hypobromous acid ion and hypochlorite ion can be particularly preferably used because the stabilization time of the etching rate of ruthenium becomes long.
• an alkaline and weakly oxidizing oxidizing agent such as hydrogen peroxide
• the concentration of hypochlorite ion in the treatment liquid of the present invention is not limited as long as it does not deviate from the gist of the present invention, but is preferably 0.1% by mass or more and 10% by mass or less.
• the concentration of the hypochlorite ions is 0.1 wt% smaller than Br - can not be efficiently oxidized to decrease the etching rate of the ruthenium.
• the amount of hypochlorite ion added is larger than 10% by mass, the stability of hypochlorite ion is lowered, which is not appropriate.
• the concentration of the oxidizing agent is more preferably 0.3% by mass or more and 7% by mass or less, and 0.5% by mass or more and 4% by mass or less. Is most preferable.
• hypochlorite ion if the ratio of hypochlorite ion to hypobromous acid ion is high, the reaction of hypochlorite ion with hypobromous acid ion proceeds to form bromate ion, so that hypobromous acid Ion concentration decreases.
• the concentration of ozone in the treatment liquid of the present invention is not limited as long as it does not deviate from the gist of the present invention, but is preferably 0.1 mass ppm or more and 1000 mass ppm (0.1 mass%) or less. Is less than 0.1 mass ppm, Br - a slow rate of oxidation to hypobromite ions, does not affect the etch rate of ruthenium. Further, from the viewpoint of stably dissolving ozone in the treatment liquid, the ozone concentration is more preferably 1 mass ppm or more and 500 mass ppm or less.
• ozone concentration is 5 mass ppm or more and 200 mass ppm or less
• Br ⁇ can be efficiently oxidized to hypobromous acid ion, which is particularly preferable.
• a method for generating ozone and a method for dissolving in a treatment liquid a widely known method can be used without any problem.
• ozone is generated by discharging to a gas containing oxygen, and the gas containing ozone is treated. By contacting with the liquid, a part or all of ozone is dissolved in the treatment liquid, and the treatment liquid containing ozone can be obtained.
• the contact between ozone and the treatment liquid may be carried out continuously or intermittently.
• the processing liquid etch ruthenium, i.e., RuO 4 / RuO 4 -
• RuO 4 When contacting / treatment liquid and ozone containing RuO 4 2-like, small amounts of ozone, by contacting the intermittently treated liquid , RuO 4 It is possible to prevent an increase in gas generation.
• the method for producing the hypochlorite ion is not particularly limited, and any hypochlorite ion generated by any method can be suitably used for the treatment liquid of the present invention.
• a method for generating hypochlorous acid ions for example, addition of hypochlorite, blowing of chlorine gas, or the like can be preferably used.
• the method of adding hypochlorite to the treatment liquid is more preferable because the concentration of hypochlorite ions can be easily controlled and the hypochlorite can be easily handled.
• hypochlorites examples include tetraalkylammonium hypochlorite, sodium hypochlorite, potassium hypochlorite, calcium hypochlorite, magnesium hypochlorite, and hypochlorous acid.
• tetraalkylammonium hypochlorite or hypochlorous acid is particularly preferable from the viewpoint that it does not contain a metal that causes a problem in semiconductor production, and it can exist stably even at a high concentration. Alkylammonium is most suitable.
• tetraalkylammonium hypochlorous acid tetraalkylammonium hypochlorous acid containing a tetraalkylammonium ion having 1 to 20 carbon atoms per alkyl group is suitable. Specifically, tetramethylammonium hypochlorite, tetraethylammonium hypochlorite, tetrapropylammonium hypochlorite, tetrabutylammonium hypochlorite, tetrapentylammonium hypochlorite, tetrahexyl hypochlorite.
• Tetramethylammonium hypochlorite and tetraethylammonium hypochlorite are more preferable from the viewpoint that they are ammonium and have a large amount of hypochlorous acid ions per unit weight. Tetramethylammonium hypochlorite is most suitable because high-purity products are easily available.
• the method for producing tetramethylammonium hypochlorite is not particularly limited, and a method produced by a widely known method can be used. For example, a method of blowing chlorine into tetramethylammonium hydroxide, a method of mixing hypochlorous acid and tetramethylammonium hydroxide, or a method of replacing a cation in a hypochlorite solution with tetramethylammonium using an ion exchange resin. Tetramethylammonium hypochlorite produced by the above method, a method of mixing a distillate of a solution containing hypochlorite with tetramethylammonium hydroxide, or the like can be preferably used.
• Br - may contain both continuously by hypochlorite or ozone Br - is BrO - Whether the oxidized on, the treatment liquid hypochlorite ions and Br contained - by quantitative ratios - ratio or ozone and Br,. If the molar concentration of Br ⁇ is higher than the molar concentration of hypochlorite ion or ozone present in the treatment liquid, the entire amount of Br ⁇ cannot be oxidized to Br O ⁇ . Therefore, the molar concentration of hypochlorite ion or ozone in the treatment liquid of the present invention is preferably higher than the molar concentration of Br ⁇ .
• the gaseous oxidant such as ozone was bubbled into the processing liquid Br - the BrO - if the oxidation, the total number of moles of gaseous oxidant to ventilation, Br contained in the processing liquid - the number of moles of More is desirable.
• hypobromous acid ions in the treatment liquid there is a method of oxidizing a bromine-containing compound with an oxidizing agent.
• the amount ratio of the bromine-containing compound and the oxidizing agent contained in the treatment liquid is the chemical quantity ratio and reaction rate when the bromine-containing compound reacts with the oxidizing agent to generate hypobromous acid ion, and the treatment liquid. included Br - and it is preferred that the oxidizing agent is determined in consideration of the reaction rate and the stoichiometric ratio at the time of reaction to occur is hypobromite ions, in practice, a plurality of sources for these reactions It is difficult to determine an appropriate amount ratio of the bromine-containing compound and the oxidizing agent because of the complex influence of each other.
• the ratio of the value obtained by dividing the concentration of the bromine-containing compound by the chemical equivalent (molar equivalent) of the bromine-containing compound to the value obtained by dividing the concentration of the oxidant by the chemical equivalent (molar equivalent) of the oxidant is 0. be in the range of 001 ⁇ 100, BrO from said bromine-containing compound oxidizing agent - not only efficiently produce, BrO - Br caused by a reduction reaction or a decomposition reaction of the - again BrO - be oxidized to Therefore, the etching rate of ruthenium is stabilized.
• the chemical equivalent (molar equivalent) and oxidation of the bromine-containing compound in the reaction between these chemical species are equal, the ratio of the molar concentration of the bromine-containing compound to the concentration of the oxidizing agent may be in the range of 0.001 to 100.
• the ratio of the molar concentration of hypobromous acid ion to the molar concentration of hypochlorite ion is in the range of 0.001 to 100. if any, BrO - again BrO by the hypochlorite ions - - Br, caused by a reduction reaction or a decomposition reaction can be oxidized to the etching rate of the ruthenium is stabilized.
• the pH of the ruthenium semiconductor treatment liquid in the present invention is preferably 8 or more and 14 or less. If less pH 8 to 14 of the process solution, ruthenium efficiently be etched, the etching rate of the ruthenium stable, further, the amount of RuO 4 gas reduction can be expected. The etching rate of the ruthenium is faster the pH is lower, RuO 4 gas generation amount as the pH is lowered is increased. Therefore, in the processing of semiconductor wafers containing ruthenium, it is very important to select a pH that is compatible with etch rate and RuO 4 gas suppression. From this viewpoint, the pH of the ruthenium semiconductor treatment liquid in the present invention is more preferably 12 or more and 14 or less, and further preferably 12 or more and less than 13. The pH of the treatment liquid by less than 12 than 13, can be etched ruthenium fast enough, further, it is possible to suppress the RuO 4 gas generation. When the pH of the treatment liquid is less than 8, RuO 2 particles tend to be generated.
• the ruthenium contained in the semiconductor wafer to which the treatment liquid of the present invention is applied may be formed by any method.
• ruthenium is a ruthenium-based metal or a ruthenium alloy.
• ruthenium-based metal in the present invention, addition of metallic ruthenium, ruthenium metal containing ruthenium 70 atomic% or more, oxides of ruthenium (RuO X), nitride (RuN), oxynitride (Runo) etc. Point to.
• the oxide of ruthenium is ruthenium dioxide and dilutenium trioxide (trihydrate).
• the "ruthenium alloy” refers to an alloy containing 70 atomic% or more and 99.99 atomic% or less of ruthenium and containing a metal other than ruthenium at a concentration higher than the concentration unavoidably contained. In the present invention, when it is not necessary to distinguish between a ruthenium-based metal and a ruthenium alloy, these are referred to as ruthenium.
• the ruthenium alloy may contain any metal other than ruthenium, but examples of the metals contained in the ruthenium alloy include tantalum, silicon, copper, hafnium, zirconium, aluminum, vanadium, cobalt, nickel, etc. Examples thereof include manganese, gold, rhodium, palladium, titanium, tungsten, molybdenum, platinum, and iridium, and these oxides, nitrides, and VDD may be contained.
• rutheniums may be intermetallic compounds, ionic compounds, or complexes. Further, ruthenium may be exposed on the surface of the wafer, or may be covered with another metal, a metal oxide film, an insulating film, a resist, or the like. Even if it is covered by another material, when the dissolution of the ruthenium occurs ruthenium in contact with the treatment solution of the present invention, RuO 4 gas generation suppression effect is exhibited. Further, the treatment liquid of the present invention, when not actively dissolve the ruthenium, i.e., be processing ruthenium is the protection of the target, it is possible to suppress the RuO 4 gas generated from ruthenium and very slightly soluble It is possible.
• the treatment liquid of the present invention when used in the ruthenium wiring forming step, it is as follows. First, a substrate made of a semiconductor (for example, Si) is prepared. The prepared substrate is subjected to an oxidation treatment to form a silicon oxide film on the substrate. After that, an interlayer insulating film made of a low dielectric constant (Low-k) film is formed, and via holes are formed at predetermined intervals. After the via hole is formed, ruthenium is embedded in the via hole by thermal CVD, and a ruthenium film is further formed. By etching with the treatment solution of the present invention the ruthenium film is flattened while suppressing RuO 4 gas generation. As a result, a highly reliable ruthenium wiring in which RuO 2 particles are suppressed can be formed.
• a substrate made of a semiconductor for example, Si
• the prepared substrate is subjected to an oxidation treatment to form a silicon oxide film on the substrate. After that, an interlayer insulating film made of a
• the treatment liquid of the present invention is a treatment liquid containing at least a bromine-containing compound, an oxidizing agent, a base compound and water.
• a bromine-containing compound used in the treatment solution of the present invention contains a bromine atom and is oxidized by an oxidizing agent described later to bromine, hypobromous acid, hypobromous acid ion, bromic acid, bromic acid ion, bromic acid.
• Bromate ion, perbromic acid, perbromate ion, bromide ion may be any compound as long as it is produced.
• the hydrogen bromide referred to here may be hydrogen bromide gas or hydrogen bromide acid which is an aqueous solution of hydrogen bromide.
• the bromine salt include lithium bromide, sodium bromide, potassium bromide, rubidium bromide, cesium bromide, ammonium bromide, onium bromide and the like.
• the onium bromide referred to here is a compound formed from onium ions and bromide ions.
• Onium ion is a compound of polyatomic cation formed by adding an excess proton (hydrogen cation) to a single atom anion.
• a compound that produces hypobromous acid or hypobromous acid ion in the treatment liquid can also be suitably used as the bromine-containing compound.
• examples of such compounds include, but are not limited to, bromohydantoins, bromoisocyanuric acids, bromsulfamic acids, bromchloramines and the like. More specific examples of the compound are 1-bromo-3-chloro-5,5-dimethylhydantoin, 1,3-dibromo-5,5-dimethylhydantoin, tribromoisocyanuric acid and the like.
• the bromine-containing compound may be added to the treatment liquid as hydrogen bromide or a bromate salt, may be added to the treatment liquid as a solution containing a bromate, or may be added to the treatment liquid as a bromate gas. Good.
• the bromine-containing compound is preferably mixed with another treatment liquid as a bromate or a solution containing a bromate or hydrogen bromide because it is easy to handle in the semiconductor manufacturing process.
• the bromine-containing compound contained in the treatment liquid may be used alone or in combination of two or more.
• the bromine-containing compound does not contain a metal because the mixing of a metal or a metal ion causes a decrease in yield.
• onium bromide contains substantially no metal, and therefore can be suitably used as the bromine-containing compound of the present invention.
• the onium bromides quaternary onium bromide, tertiary onium bromide, and hydrogen bromide are industrially easily available and easy to handle, and thus, as the bromine-containing compound of the present invention. It is more suitable.
• Quaternary onium bromide is a bromate composed of ammonium ions or phosphonium ions that can be stably present in the treatment liquid.
• quaternary onium bromide tetramethylammonium bromide, tetraethylammonium bromide, tetrapropylammonium bromide, tetrabutylammonium bromide, tetrapentylammonium bromide, tetrahexylammonium bromide, methyl bromide Triethylammonium, diethyldimethylammonium bromide, trimethylpropylammonium bromide, butyltrimethylammonium bromide, trimethylnonylammonium bromide, decyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, trimethyl bromide
• a compound in which a proton is added to a tertiary amine, a secondary amine, or a primary amine can also be used as a bromine-containing compound.
• bromine-containing compounds include methylamine hydrobromide, dimethylamine hydrobromide, ethylamine hydrobromide, diethylamine hydrobromide, triethylamine hydrobromide, and 2-bromoethylamine.
• Hydrobromide 2-bromoethyldiethylamine hydrobromide, ethylenediamine dihydrobromide, propylamine hydrobromide, butylamine hydrobromide, tert-butylamine hydrobromide, neopentyl Amine hydrobromide, 3-bromo-1-propylamine hydrobromide, dodecylamine hydrobromide, cyclohexaneamine hydrobromide, benzylamine hydrobromide and the like.
• Tertiary onium bromide is a bromate consisting of sulfonium ions that can be stably present in the treatment solution.
• tertiary sulfonium bromide trimethylsulfonium bromide, triethylsulfonium bromide, tripropylsulfonium bromide, tributylsulfonium bromide, triphenylsulfonium bromide,- (2carboxyethyl) dimethylsulfonium bromide, etc.
• quaternary onium bromide which is a bromate composed of ammonium ions, is preferable because of its high stability, industrial availability of high-purity products, and low cost.
• the quaternary onium bromide is preferably tetraalkylammonium bromide, which has particularly excellent stability and can be easily synthesized.
• the carbon number of the alkyl group is not particularly limited, and the carbon number of the four alkyl groups may be the same or different.
• alkylammonium bromide tetraalkylammonium bromide having 1 to 20 carbon atoms per alkyl group can be preferably used.
• tetraalkylammonium bromide which has a small number of carbon atoms in the alkyl group, can be more preferably used because the number of bromine atoms per weight is large.
• Examples include tetramethylammonium bromide, tetraethylammonium bromide, tetrapropylammonium bromide, tetrabutylammonium bromide, tetrapentylammonium bromide, tetrahexylammonium bromide, and the like, among which tetramethylammonium bromide. , Tetraethylammonium bromide, tetrapropylammonium bromide, tetrabutylammonium bromide are preferred, and tetramethylammonium bromide is most preferred.
• the number of bromine-containing compounds contained in the treatment liquid may be one or plural.
• tetraalkylammonium bromide used in the present invention commercially available tetraalkylammonium bromide may be used, or tetraalkylammonium bromide produced from tetraalkylammonium ions and bromide ions is used. It doesn't matter.
• the method for producing tetraalkylammonium bromide is simply to mix an aqueous solution containing tetraalkylammonium hydroxide and an aqueous solution containing bromide ions, or a bromine-containing gas that generates bromide ions when dissolved in water, such as hydrogen bromide. Good.
• tetraalkylammonium hydroxide used for producing tetraalkylammonium bromide examples include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide. Among them, tetramethylammonium hydroxide is more preferable because the number of hydroxide ions per unit weight is large and a high-purity product is easily available.
• Bromine ion sources that generate bromide ions used to produce tetraalkylammonium bromide include hydrogen bromide, lithium bromide, sodium bromide, potassium bromide, rubidium bromide, cesium bromide, and ammonium bromide. And so on. Of these, hydrogen bromide is preferable because it does not contain a metal substantially, is easily available industrially, and a high-purity product is easily available.
• the amount of the bromine-containing compound added is not particularly limited, and may be determined in consideration of the etching rate of ruthenium, the stability of the treatment liquid, the solubility of the bromine-containing compound, the cost, and the like.
• the bromine-containing compound added to the treatment liquid is oxidized by an oxidizing agent described later, and is a chemical species effective for etching ruthenium, specifically, bromine (Br 2 ), hypobromous acid (HBrO), and hypobromous acid.
• the treatment liquid containing HBrO, BrO ⁇ , HBrO 2 , BrO 2 ⁇ , HBrO 3 and BrO 3 ⁇ has a high ruthenium etching rate, so that the treatment liquid is a chemical species of these species. Is preferably included.
• a treatment liquid containing a large amount of HBrO and BrO ⁇ (hereinafter, also referred to as BrO ⁇ or the like) is more preferable in that the processing time can be shortened because the etching rate of ruthenium is particularly high.
• the etching rate of ruthenium can be increased. Specifically, ruthenium can be efficiently etched by setting the treatment liquid in which the ratio of BrO ⁇ in 1 mol of the bromine element contained in the treatment liquid exceeds 0.5 mol.
• the treatment liquid contains an oxidizing agent capable of reoxidizing Br ⁇ to a chemical species effective for etching ruthenium. If such an oxidizing agent is present in the treatment liquid, the concentration of the chemical species effective for ruthenium etching can be kept high, and the ruthenium etching rate can be maintained.
• HBrO 3 or BrO 3 ⁇ and Br ⁇ may be generated via HBrO 2 or BrO 2 ⁇ .
• the treatment liquid of the present invention may contain one or more of the above-mentioned decomposition products of BrO ⁇ .
• the treatment liquid of the present invention containing BrO ⁇ and BrO 3 ⁇ can be suitably used for etching ruthenium.
• the ratio of BrO ⁇ in 1 mol of bromine element contained in the treatment liquid is preferably more than 0.5 mol.
• the treatment liquid can have a ratio of more than 0.5 mol.
• the alkaline processing liquid, bromine-containing compounds or Br - is directly BrO an oxidizing agent - is to be oxidized to the like.
• the oxidation of Br ⁇ with an oxidizing agent and the etching of ruthenium can be repeated and continuously performed. That, (A) Br - reaction and is oxidized to effective chemical species to etch the ruthenium by an oxidizing agent, Br by etching a ruthenium effective chemical species for etching (B) ruthenium - Return to the reaction , Repeat. As a result, the ratio of BrO ⁇ in 1 mol of the bromine element in the treatment liquid exceeds 0.5 mol, and ruthenium can be efficiently etched.
• the (A) Br - When reaction is oxidized to effective chemical species to etch the ruthenium by an oxidizing agent progresses, the oxidizing agent in the treatment liquid is consumed. When the oxidizing agent in the processing solution resulting in all used in the reaction, more, a bromine-containing compound or Br - oxidation will not occur. However, in a treatment solution containing many chemical species effective for ruthenium etching, that is, a treatment solution in which the ratio of BrO ⁇ in 1 mol of bromine element exceeds 0.5 mol, the ruthenium etching ability is not immediately lost. Ruthenium can be etched until there are no effective chemicals for etching ruthenium in the treatment solution.
• a bromine-containing compound or Br in an acidic treatment solution - Doing oxidation of ruthenium effective chemical species for etching, a bromine-containing compound or Br - is oxidized with an oxidizing agent, bromine gas is generated.
• bromine gas When the bromate gas is absorbed by an alkali, hypobromous acid and bromate are produced in a molar ratio of 1: 1. Therefore, the ratio of BrO ⁇ contained in the treatment liquid is 0.5 mol with respect to 1 mol of the bromine element contained in the treatment liquid, and does not exceed 0.5.
• the ratio of BrO ⁇ contained in the treatment liquid was based on 1 mol of the bromine element contained in the treatment liquid. Less than 0.5.
• Bromine-containing compound under acidic conditions or Br - perform oxidation of ruthenium effective chemical species for etching, when etching the ruthenium alkaline, and generation of effective chemical species for etching ruthenium with an oxidizing agent, ruthenium
• the time required for generating bromine gas and the time required for adjusting the pH of the treatment liquid are required, so that the ruthenium etching process becomes intermittent and the productivity is significantly deteriorated. Therefore, the generation of chemical species effective for etching ruthenium by an oxidizing agent under acidic conditions must be performed only once before etching ruthenium. In this case, since the reactions (A) and (B) above do not occur repeatedly and continuously, the ratio of BrO ⁇ in 1 mol of the bromine element contained in the treatment liquid is 0.5 or less.
• the ratio of BrO ⁇ in 1 mol of bromine element contained in the treatment liquid exceeds 0.5 mol.
• the stability of the ruthenium etching rate, the number of ruthenium films that can be etched, and the lifetime of the treatment liquid are significantly reduced. Therefore, in order to stably and efficiently etch ruthenium, it is necessary to make the treatment liquid alkaline and to use a treatment liquid in which the ratio of BrO ⁇ in 1 mol of bromine element contained in the treatment liquid exceeds 0.5 mol. preferable.
• the amount of the bromine-containing compound added to the bromine-containing compound is preferably 0.008% by mass or more and less than 10% by mass as the amount of bromine element with respect to the total mass of the treatment liquid. If it is less than 0.008% by mass, the ruthenium etching rate is slow and the practicality is low. If it is 10% by mass or more, it is difficult to control the etching rate of ruthenium, and it is difficult to control it as a manufacturing process. Therefore, from the viewpoint of high etching rate and efficient production by controlling the etching rate, the amount of the bromine-containing compound added to the treatment liquid of the present invention is 0.008% by mass or more and 10% by mass as the amount of bromine element. It is preferably less than.
• the upper limit of the addition amount of the bromine-containing compound contained in the treatment liquid of the present invention is more preferably less than 2% by mass as the amount of bromine element. If the added amount of bromine-containing compounds is less than 2.0 wt%, effective chemical species to etch the ruthenium, in particular, HBrO, BrO -, HBrO 2 , BrO 2 - disproportionation reaction hardly occurs, and these Fluctuations in the concentration of chemical species can be suppressed, and the etching rate becomes more stable.
• the amount of the bromine-containing compound added is less than 2.0% by mass, the RuO 4 gas concentration generated per hour can be suppressed low by controlling the etching rate of ruthenium, and the generation of RuO 2 particles can be suppressed. Can be less.
• the lower limit of the addition amount of the bromine-containing compound contained in the treatment liquid of the present invention is more preferably 0.01% by mass or more as the amount of bromine element. When the amount of the bromine-containing compound added is 0.01% by mass or more, a chemical species effective for etching ruthenium is efficiently generated, the etching rate is further increased, and ruthenium is efficiently produced at a stable etching rate. Can be etched.
• the amount of the bromine-containing compound added to the treatment liquid of the present invention is more preferably 0.01% by mass or more and less than 2% by mass as the amount of bromine element. Further, from the viewpoint of increasing the throughput and improving the production efficiency, the amount of the bromine-containing compound added is more preferably 0.04% by mass or more and less than 2.0% by mass as the amount of the bromine element. Further, from the viewpoint that the etching rate becomes more stable because reoxidation to a chemical species effective for etching ruthenium by an oxidizing agent is likely to occur, the amount of the bromine-containing compound added is 0.08 mass as the amount of bromine element. Most preferably, it is% or more and less than 2.0% by mass.
• the pH of the solution containing the bromine-containing compound is not particularly limited, but the pH is preferably 8 or more and 14 or less, and more preferably 12 or more and 13 or less. With a solution in this pH range, the pH drop that occurs when the solution containing the oxidizing agent described later and the solution containing the bromine-containing compound are mixed can be reduced, and the treatment solution of the present invention can be stably produced. , Can be saved and used.
• the pH of the solution containing the bromine-containing compound is less than 8, when the solution containing the oxidizing agent described later and the solution containing the bromine-containing compound are mixed, the pH of the treated solution after mixing becomes alkaline. Therefore, the pH and amount of the solution containing the bromine-containing compound may be adjusted.
• iodine contained in the iodine-containing compound can be a chemical species that etches ruthenium by being oxidized by an oxidizing agent contained in the treatment liquid.
• the oxidizing agent used in the treatment liquid of the present invention has a function of oxidizing a bromine-containing compound and producing a chemical species effective for etching ruthenium. Specifically, nitrate, sulfuric acid, persulfate, peroxodisulfuric acid, hypochlorous acid, chloric acid, chloric acid, perchloric acid, hypobromic acid, bromous acid, bromic acid, perbromic acid, hypochlorous acid Iodine acid, hypoiodous acid, iodic acid, periodic acid, salts thereof, and ions generated by dissociation of these salts, as well as hydrogen peroxide, ozone, fluorine, chlorine, bromine, iodine, permanganate, Chromate, dichromate, cerium salt and the like can be mentioned. These oxidizing agents may be used alone or in combination of two or more. When adding these oxidizing agents to the treatment liquid of the present invention, one of solid, liquid, and gas may be mentioned.
• hypochlorous acid, chloric acid, chloric acid, perchloric acid, hypobromic acid, bromine acid, bromine acid, perbromic acid, hypoiodous acid can exist stably even in alkaline conditions.
• Hypoiodous acid, chlorous acid, periodic acid, and salts thereof, and ions, ozone or hydrogen peroxide generated by dissociation of these salts preferably hypoiodous acid, chloric acid, chloric acid, perchlorine.
• Acids, hypobromic acid, bromine acid, bromine acid, perbromic acid, and salts thereof, and ions, ozone or hydrogen peroxide generated by dissociation of these salts are more preferable, and hypochlorate ion or ozone. Is more preferable, and hypochlorate ion is most preferable.
• hypochlorous acid its salt, tetraalkylammonium hypochlorite, or ozone
• hypochlorous acid its salt, tetraalkylammonium hypochlorite, or ozone
• tetraalkylammonium hypochlorite is particularly suitable because it exists stably even in an alkali and can efficiently oxidize the bromine-containing compound.
• the concentration of the oxidizing agent is not particularly limited, and an amount capable of oxidizing the bromine-containing compound to a chemical species effective for etching ruthenium may be added.
• the amount of the oxidizing agent added is preferably 0.1% by mass or more and 10% by mass or less. If the amount of the oxidizing agent added is less than 0.1 mass ppm, the bromine-containing compound cannot be efficiently oxidized, and the etching rate of ruthenium decreases. That is, the etching rate is low in the composition in which the oxidizing agent is not mixed. On the other hand, if the amount of the oxidizing agent added is larger than 10% by mass, the stability of the oxidizing agent is lowered, which is not suitable.
• etch rate of RuO 4 gas suppression and ruthenium concentration of the oxidizing agent is more preferably 0.1 mass% to 10 mass%, is more than 0.3 wt% 7 wt% or less It is more preferable, and it is most preferable that it is 0.5% by mass or more and 4% by mass or less.
• the oxidizing agent is ozone, it is preferably in the above-mentioned concentration range.
• the pH of the solution containing the oxidizing agent is not particularly limited, but it is preferably pH 8 or more and 14 or less, and more preferably 12 or more and 13 or less. With a solution in this pH range, the pH drop that occurs when the solution containing the bromine-containing compound and the solution containing the oxidizing agent are mixed can be reduced, and the treatment solution of the present invention can be stably produced. It can be saved and used.
• the pH of the solution containing the oxidant is less than 8, the pH of the treated solution after mixing becomes alkaline when the solution containing the bromine-containing compound and the solution containing the oxidant are mixed. , The pH and the amount of the solution containing the oxidizing agent may be adjusted.
• tetraalkylammonium hypochlorite is preferable as the oxidizing agent that may be contained in the treatment liquid of the present invention. Therefore, a preferred embodiment of the method for producing tetraalkylammonium hypochlorite will be described below.
• the method for producing the oxidizing agent includes a preparatory step of preparing a tetraalkylammonium hydroxide solution and a reaction step of bringing chlorine into contact with the tetraalkylammonium hydroxide solution.
• the tetraalkylammonium hydroxide solution contains carbon dioxide, which is usually derived from the atmosphere. Carbon dioxide is present in the solution as carbonate ions or bicarbonate ions.
• the carbon dioxide concentration is not particularly limited, but in terms of carbonate ions, it is preferably 0.001 ppm or more and 500 ppm or less (based on mass), more preferably 0.005 ppm or more and 300 ppm or less, and 0. It is more preferably 01 ppm or more and 100 ppm or less.
• the concentration of carbon dioxide contained in the tetraalkylammonium hydroxide solution is 0.001 ppm or more and 500 ppm or less, the pH change of the obtained tetraalkylammonium hypochlorous acid solution can be suppressed. As a result, the storage stability of the tetraalkylammonium hypochlorite solution can be improved.
• the tetraalkylammonium hydroxide solution is preferably a solution of tetraalkylammonium hydroxide having 1 to 10 carbon atoms in the alkyl group, and the tetraalkylammonium hydroxide solution having 1 to 5 carbon atoms. More preferably, it is a solution.
• Specific examples of tetraalkylammonium hydroxide include tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrabutylammonium hydroxide. These tetraalkylammonium hydroxides may be used alone or in combination of two or more. Further, the carbon numbers of the four alkyl groups contained in tetraalkylammonium hydroxide may be the same or different.
• reaction process in which chlorine is brought into contact with a tetraalkylammonium hydroxide solution
• a tetraalkylammonium hydroxide solution By contacting and reacting the tetraalkylammonium hydroxide solution with chlorine, the hydroxide ion of tetraalkylammonium hydroxide is replaced with the hypochlorite ion generated by chlorine, and the tetraalkylammonium hypochlorite solution is replaced. Is generated.
• the upper limit of the carbon dioxide concentration in the gas phase portion is 100 volume ppm, but if it is 0.001 to 100 volume ppm, preferably 0.01 to 80 volume ppm, hypochlorous acid.
• the pH of the tetraalkylammonium solution can be sufficiently controlled, and a tetraalkylammonium hypochlorite solution having excellent storage stability can be produced.
• the pH range of the liquid phase portion in the reaction step of this embodiment is 10.5 or more.
• the upper limit is not particularly limited, but if the pH during the reaction is excessively high, hypochlorite ions may be decomposed and the effective chlorine concentration may decrease when stored at the same pH for a long period of time after the reaction is completed. Therefore, the pH of the liquid phase portion in the reaction step is preferably less than 14, more preferably less than 13.9, and even more preferably 11 or more and less than 13.8.
• the pH is in the above range, the decomposition of hypochlorite ions is suppressed during the storage of the obtained tetraalkylammonium hypochlorite solution, and the storage stability is improved.
• the reaction temperature range of the tetraalkylammonium hydroxide solution in the reaction step of the present embodiment is preferably ⁇ 35 ° C. or higher and 25 ° C. or lower, more preferably ⁇ 15 ° C. or higher and 25 ° C. or lower, and further preferably 0 ° C. or higher and 25 ° C. or lower. ..
• the reaction temperature is within the above range, the tetraalkylammonium hydroxide solution and chlorine react sufficiently, and a tetraalkylammonium hypochlorous acid solution can be obtained with high production efficiency.
• the tetraalkylammonium hypochlorite solution obtained by the production method of the present embodiment has excellent storage stability and is suitably used as an oxidizing agent contained in the treatment liquid of the present invention. be able to.
• the base compound used in the treatment liquid of the present invention is not particularly limited, but is limited to lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, magnesium hydroxide, calcium hydroxide, and the like.
• Strontium hydroxide, barium hydroxide, ammonia, choline, alkylammonium hydroxide and the like are used.
• sodium hydroxide, potassium hydroxide, ammonia, choline, and alkylammonium hydroxide are suitable because they are easily available and a high ruthenium etching rate can be obtained when used in a treatment solution. ..
• ammonia, choline, and alkylammonium hydroxide do not contain metals, they can be particularly preferably used as the treatment liquid of the present invention.
• alkylammonium hydroxide tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide and the like are industrially available, and high-purity grades for semiconductor production are easily available. Tetramethylammonium hydroxide is most preferred in that it is possible.
• the basic compound can be added to the treatment liquid as a solid or an aqueous solution.
• the concentration of the basic compound is not particularly limited as long as it does not deviate from the object of the present invention, but the pH of the solution containing the basic compound is preferably in the range of pH 8 or more and 14 or less, and more preferably 12 or more and 13 or less. preferable.
• the pH of the solution containing the basic compound is within this pH range, the pH decrease caused when the solution containing the oxidizing agent and the solution containing the bromine-containing compound are mixed can be reduced, and the treatment of the present invention can be reduced.
• the liquid can be stably produced, stored and used.
• the water contained in the treatment liquid of the present invention is preferably water from which metal ions, organic impurities, particle particles, etc. have been removed by distillation, ion exchange treatment, filter treatment, various adsorption treatments, etc., particularly pure water and ultrapure water. Is preferable.
• Such water can be obtained by a known method widely used in semiconductor manufacturing.
• the pH of the treatment solution of the present invention is preferably 8 or more and 14 or less. If the pH of the processing solution in this range, ruthenium etched fast enough, and it is possible to suppress the RuO 4 gas generation. When the pH of the treatment liquid is lower than 8, the generation of RuO 2 particles becomes remarkable, and the yield of the semiconductor element deteriorates. On the other hand, when the pH of the treatment liquid exceeds 14, the oxidizing agent is decomposed, so that the oxidation of the bromine-containing compound may not be constant. This means that the etching rate of ruthenium is not constant and should be avoided because it complicates process control in the semiconductor manufacturing process.
• RuO 4 gas generation amount due to the etching of the ruthenium is less as the pH of the treatment liquid is high.
• the etching rate of ruthenium decreases as the pH of the treatment liquid increases. Therefore, from the viewpoint of achieving both of RuO 4 gas suppressed and the etching rate, pH of the treatment liquid is preferably 12 to 14, more preferably, be less than 12 or more 13, more preferably. If the pH is above the range of the treatment liquid, effective chemical species for etching the ruthenium contained in the treatment solution of the present invention is to dissolve the ruthenium sufficient etching rate, and can inhibit RuO 4 gas generation.
• the pH at which the ruthenium metal is etched is preferably 11 or more and 14 or less, and more preferably 12 or more and less than 13. PH of the treatment solution is within this range, the etching of ruthenium metal, it is possible to etch rate and RuO 4 gas yield decreased.
• the pH at which the ruthenium alloy is etched is preferably 12 or more and 14 or less, and more preferably 12 or more and less than 13.
• the treatment liquid of the present invention contains a bromine-containing compound, an oxidizing agent, a base compound and water
• the treatment liquid may be one liquid, two liquids or more.
• the treatment solution is a single solution, it becomes a solution containing all of the bromine-containing compound, the oxidizing agent, the base compound and water.
• the treatment liquid may be produced by mixing each liquid.
• each liquid contains at least one or more of a bromine-containing compound, an oxidizing agent, a base compound, and water. Further, other components described later may be contained.
• the bromine-containing compound, the oxidizing agent, and the base compound are simultaneously present in the treatment liquid, so that the bromine-containing compound is oxidized by the oxidizing agent, and the ruthenium A chemical species that is effective for etching is generated.
• the treatment liquid When a plurality of treatment liquids are used, it is preferable to divide the treatment liquid into a treatment liquid containing a bromine-containing compound and a treatment liquid containing an oxidizing agent. By separating the bromine-containing compound and the oxidizing agent, oxidation of the bromine-containing compound by the oxidizing agent can be prevented, and the treatment liquid of the present invention can be stably stored.
• a widely known method can be used as a method for mixing the semiconductor chemical solution.
• a method using a mixing tank a method of mixing in the piping of a semiconductor manufacturing apparatus (in-line mixing), a method of mixing by simultaneously applying a plurality of liquids on a wafer, and the like can be preferably used.
• the treatment liquids may be mixed at any time.
• it takes time to oxidize the bromine-containing compound it is possible to provide a time to generate a chemical species effective for ruthenium etching by mixing the treatment liquid before etching ruthenium.
• the time required for oxidation is preferably short, and preferably 1 hour or less.
• the time required for oxidation of the bromine-containing compound can be controlled by appropriately selecting the oxidant concentration, the bromine-containing compound concentration, the pH of the treatment liquid, the temperature of the treatment liquid, the stirring method of the treatment liquid, and the like.
• the concentrations of both the oxidizing agent and the bromine-containing compound may be increased, or only one of them may be increased.
• the time required for oxidation of the bromine-containing compound can be shortened.
• the concentration of a chemical species effective for etching ruthenium is low, the lifetime of the treatment liquid may be short and it may be difficult to control the manufacturing process. In such a case, it is preferable to perform mixing immediately before performing ruthenium etching.
• a solution containing an oxidizing agent and a basic compound and a solution containing a bromine-containing compound it is preferable to mix a solution containing an oxidizing agent and a basic compound and a solution containing a bromine-containing compound, and a solution containing hypochlorite ion and a basic compound and bromine. It is more preferable to mix with a solution containing the contained compound.
• the solution containing the hypochlorite ion and the base compound is preferably alkaline. Further, for mixing, it is preferable to add the bromine-containing compound to the solution containing the oxidizing agent and the base compound.
• the oxidizing agent is an alkaline solution containing hypochlorous acid and the solution containing a bromine-containing compound is an acidic solution, when the former is gradually added to the latter, hypochlorous acid is contained in the acidic solution.
• the solution containing the oxidizing agent and the basic compound and the solution containing the bromine-containing compound may be either a solution or an aqueous solution, but when the solvent is other than water, such as an organic or inorganic solvent, the solvent reacts with the oxidizing agent. There is a risk that the oxidizing agent will be decomposed by doing so. For this reason, the solution is preferably an aqueous solution.
• the pH of the treatment liquid after mixing is alkaline.
• the pH of the treatment liquid is preferably 8 or more and 14 or less.
• the concentration of the base compound and / or water is adjusted so that the treatment liquid after mixing (including bromine-containing compound, oxidizing agent, base compound and water) has pH 8 or more and 14 or less. adjust.
• the pH of the mixed treatment liquids may be the same or different.
• the pH of the treatment liquid after mixing does not change significantly, and it can be suitably used as an etching solution for ruthenium.
• the composition after mixing (bromine-containing compound concentration, oxidant concentration, basic compound concentration, pH) is within the above range.
• the mixing method such as the mixing ratio and the mixing order of the treatment liquids to be mixed is not particularly limited. However, for example, when an alkaline solution containing a hypochlorous acid compound and an acidic solution containing a bromine-containing compound are mixed, the decomposition of the hypochlorous acid compound may proceed locally. It is preferable to mix an acidic solution containing a bromine-containing compound with an alkaline solution containing a hypochlorous acid compound.
• the hypochlorous acid compound refers to a compound that produces hypochlorous acid or hypochlorite ion in the treatment liquid.
• the hypochlorous acid compound include hypochlorous acid, hypochlorite, hydantoins, isocyanuric acids, sulfamic acids, chloramines and the like.
• hypochlorous acid and hypochlorite are preferable because they can efficiently generate hypochlorous acid or hypochlorite ions.
• hypochlorous acid tetraalkylammonium hypochlorite is preferable, and among them, tetramethylammonium hypochlorite is used because the amount of hypochlorous acid or hypochlorite ion per unit weight is large. More preferably.
• the chemical species effective for etching ruthenium produced by oxidizing a bromine-containing compound with an oxidizing agent vary depending on the pH of the treatment liquid, redox potential (ORP), etc., but are mainly bromine or bromide ion, and then Bromous acid, bromous acid, bromic acid, perbromic acid and their ions.
• the contents of metals specifically sodium, potassium, aluminum, magnesium, iron, nickel, copper, silver, cadmium, and lead are 1 ppb or less, respectively.
• the amount of ammonia and amines contained in the treatment solution of the present invention and the bromine-containing compound, oxidizing agent, base compound, water, solvent, and other additives used in the treatment solution is small. This is because when ammonia and amines are present in the treatment liquid, they react with an oxidizing agent, a bromine-containing compound, a chemical species effective for etching ruthenium generated from the bromine-containing compound, and the like, and the stability of the treatment liquid is lowered. For example, when tetramethylammonium hydroxide is used as the base compound, ammonia and amines contained in the base compound, particularly trimethylamine, may cause a decrease in the stability of the treatment liquid.
• the total amount of amines contained in the basic compound is preferably 100 ppm or less. If the total amount of amines is 100 ppm or less, the effect of the reaction with chemical species effective for etching ruthenium generated from the oxidizing agent, bromine-containing compound, and bromine-containing compound is minor, and the stability of the treatment liquid is impaired. There is no.
• the treatment liquid of the present invention When the treatment liquid of the present invention is produced, it is preferable to shield it from light in order to prevent decomposition of an oxidizing agent by light, a chemical species effective for etching ruthenium generated from a bromine-containing compound, and the like.
• the treatment liquid of the present invention it is preferable to prevent the dissolution of carbon dioxide in the treatment liquid.
• the treatment liquid of the present invention is alkaline
• carbon dioxide can easily dissolve in the treatment liquid and cause a pH change.
• the pH of the treatment liquid changes not only the etching rate of ruthenium fluctuates, but also the stability of the treatment liquid decreases.
• the dissolution of carbon dioxide in the treatment liquid can be reduced by a method such as flowing an inert gas to purge the carbon dioxide in the production apparatus or carrying out the reaction in an atmosphere of the inert gas. If the amount of carbon dioxide in the manufacturing apparatus is 100 ppm or less, the effect of dissolving carbon dioxide can be ignored.
• the surface of the reaction vessel in contact with the treatment liquid is made of glass or an organic polymer material.
• the contamination of impurities such as metals, metal oxides, and organic substances can be further reduced.
• the organic polymer material used for the inner surface of the reaction vessel include vinyl chloride resin (soft / hard vinyl chloride resin), nylon resin, silicone resin, polyolefin resin (polyethylene, polypropylene), fluorine resin and the like. Can be used. Among them, a fluororesin is preferable in consideration of ease of molding, solvent resistance, and less elution of impurities.
• the fluororesin is not particularly limited as long as it is a resin (polymer) containing a fluorine atom, and a known fluororesin can be used.
• a resin polymer
• a known fluororesin can be used.
• examples thereof include a trifluoroethylene-ethylene copolymer and a cyclized polymer of perfluoro (butenyl vinyl ether).
• the treatment liquid of the present invention may contain other additives conventionally used in the treatment liquid for semiconductors, as long as the object of the present invention is not impaired.
• other additives include acids, metal corrosion inhibitors, water-soluble organic solvents, fluorine compounds, oxidizing agents, reducing agents, complexing agents, chelating agents, surfactants, defoamers, pH adjusters, stabilizers. Etc. can be added. These additives may be added alone or in combination of two or more.
• the treatment liquid of the present invention may contain alkali metal ions, alkaline earth metal ions, etc. due to the origin of these additives and the convenience of manufacturing the treatment liquid.
• alkali metal ions, alkaline earth metal ions, etc. due to the origin of these additives and the convenience of manufacturing the treatment liquid.
• sodium ion, potassium ion, calcium ion and the like may be contained.
• these alkali metal ions, alkaline earth metal ions, etc. remain on the semiconductor wafer, they adversely affect the semiconductor element (adverse effects such as a decrease in the yield of the semiconductor wafer), so the amount thereof is preferably small. , Actually, it is better not to be included infinitely.
• the pH adjuster is preferably not an alkali metal hydroxide such as sodium hydroxide or an alkaline earth metal hydroxide, but an organic alkali such as ammonia, amine, choline or tetraalkylammonium hydroxide.
• the total amount of the alkali metal ion and the alkaline earth metal ion is preferably 1% by mass or less, more preferably 0.7% by mass or less, and 0.3% by mass or less. It is more preferably 10 ppm or less, and most preferably 500 ppb or less.
• the treatment liquid of the present invention may further contain an organic solvent.
• the treatment liquid of the present invention containing an organic solvent can suppress the gas generation of RuO 4. Any organic solvent may be used as long as the function of the treatment liquid of the present invention is not impaired. Examples include sulfolane, acetonitrile, carbon tetrachloride, 1,4-dioxane and the like, but of course, the organic solvent is not limited to these.
• the temperature at the time of etching the ruthenium with a treating solution of the present invention is not particularly limited, the etching rate of ruthenium, stability of the processing solution may be determined by considering the RuO 4 gas yield.
• the treatment temperature is preferably lower.
• the etching rate of ruthenium increases as the temperature increases. From the viewpoint of achieving both the etch rate of RuO 4 gas suppression and ruthenium, the temperature is preferably 10 ° C. ⁇ 90 ° C. to etch ruthenium, more preferably from 15 ° C. ⁇ 70 ° C., and most preferably from 20 °C ⁇ 60 °C.
• the treatment time for etching ruthenium with the treatment liquid of the present invention is in the range of 0.1 to 120 minutes, preferably 0.3 to 60 minutes, and may be appropriately selected depending on the etching conditions and the semiconductor element used. ..
• an organic solvent such as alcohol can be used, but rinsing with deionized water is sufficient.
• the treatment solution of the present invention to suppress the generation of RuO 4 gas, and the ruthenium adhering to the end face or the back surface of the semiconductor wafer can be removed at a sufficient etching rate (10 ⁇ / min or higher).
• a sufficient etching rate 10 ⁇ / min or higher.
• the hypobromous acid ion concentration, hypochlorite ion concentration, bromine-containing compound concentration, oxidant concentration, pH of the treatment liquid, treatment temperature, etc. contained in the treatment liquid The contact method between the treatment liquid and the wafer may be appropriately selected.
• the ruthenium-based metal film and / or the ruthenium alloy film deposited on the substrate can be etched with the treatment liquid.
• the treatment liquid of the present invention is preferably stored at a low temperature and / or in a light-shielded manner.
• the treatment liquid of the present invention is preferably stored at a low temperature and / or in a light-shielded manner.
• the stability of the treatment liquid can be maintained by storing the treatment liquid in a container filled with an inert gas to prevent carbon dioxide from being mixed.
• the inner surface of the container that is, the surface in contact with the treatment liquid is preferably formed of glass or an organic polymer material.
• the inner surface of the reaction vessel is made of glass or an organic polymer material, the contamination of impurities such as metals, metal oxides, and organic substances can be further reduced.
• the organic polymer material used for the inner surface of the reaction vessel the material exemplified in the production of the treatment liquid of the present invention can be preferably used.
• the pH at which the treatment liquid is stored can be appropriately selected, but the pH of the treatment liquid is alkaline in order to prevent decomposition of hypobromous acid ions, bromine-containing compounds, oxidizing agents, and other additives. It is preferably 8 or more and 14 or less, and most preferably 12 or more and 14 or less.
• the ruthenium film used in Examples and Comparative Examples was formed as follows. An oxide film was formed on a silicon wafer using a batch thermal oxidation furnace, and ruthenium was formed on the silicon wafer by a sputtering method at 1200 ⁇ ( ⁇ 10%). The sheet resistance was measured by a four-probe resistance measuring device (Loresta-GP, manufactured by Mitsubishi Chemical Analytech Co., Ltd.) and converted into a film thickness to obtain the ruthenium film thickness before etching. After the etching treatment, the sheet resistance was similarly measured with a four-probe resistance measuring device and converted into a film thickness to obtain the ruthenium film thickness after the etching treatment. The difference between the ruthenium film thickness after the etching treatment and the ruthenium film thickness before the etching treatment was defined as the amount of change in the film thickness before and after the etching treatment.
• the ruthenium dioxide film used in the examples was formed as follows. An oxide film was formed on a silicon wafer using a batch thermal oxidation furnace, and ruthenium dioxide was formed on the silicon wafer by a sputtering method at 1000 ⁇ ( ⁇ 10%). The sheet resistance was measured by a four-probe resistance measuring device (Loresta-GP, manufactured by Mitsubishi Chemical Analytech Co., Ltd.) and converted into a film thickness to obtain the ruthenium dioxide film thickness before the etching treatment. After the etching treatment, the sheet resistance was similarly measured with a four-probe resistance measuring device and converted into a film thickness to obtain the ruthenium dioxide film thickness after the etching treatment. The difference between the ruthenium dioxide film thickness after the etching treatment and the ruthenium dioxide film thickness before the etching treatment was defined as the amount of change in the film thickness before and after the etching treatment.
• each sample piece having a size of 10 ⁇ 20 mm was immersed in a treatment liquid at 60 ° C. for 1 minute to perform an etching treatment of ruthenium or ruthenium dioxide.
• the value obtained by dividing the amount of change in film thickness before and after the etching treatment by the immersion time was calculated as the etching rate and evaluated as the etching rate in the present invention.
• the treatment temperature and treatment time are shown in Table 5. When the amount of change in film thickness before and after the treatment was less than 5 angstroms, it was assumed that the film was not etched.
• the amount of ruthenium in this absorption liquid was measured by ICP-OES, and the amount of Ru in the generated RuO 4 gas was determined.
• the fact that all the ruthenium on the Si wafer immersed in the treatment liquid was dissolved was determined by measuring the sheet resistance before and after immersion with a four-probe resistance measuring device (Loresta-GP, manufactured by Mitsubishi Chemical Analytech Co., Ltd.). Confirmed by converting to thickness.
• the amount of RuO 4 gas generated was evaluated using the value obtained by dividing the weight of Ru contained in the RuO 4 gas absorbing solution by the area of the wafer with Ru. When the amount of RuO 4 gas generated was 40 ⁇ g / cm 2 or less, the generation of RuO 4 gas was considered to be suppressed.
• Tables 1 to 4 show the composition of the treatment solution
• Table 5 shows the evaluation results
• Table 6 shows the preparation conditions of the treatment solution
• Table 7 shows the production conditions of the oxidizing agent
• Table 8 shows the hypochlorite at 25 ° C. ion (ClO -) / Cl - system and hypobromite ion (BrO -) / Br - redox potential (calculated value) of the system, shows the preparation conditions of tetramethylammonium bromide solution in Table 9.
• Example 1> (Preparation of sample to be etched) A ruthenium film was formed by the method described in (Ruthenium film formation and film thickness change amount), and a sample piece cut into 10 ⁇ 20 mm was used for evaluation.
• thermometer protection tube manufactured by Cosmos Bead, bottom-sealed type
• thermometer manufactured by Cosmos Bead, bottom-sealed type
• the tip of a PFA tube (Flon Kogyo Co., Ltd., F-8011-02), which is connected to a chlorine gas cylinder and a nitrogen gas cylinder in one opening and is in a state where chlorine gas / nitrogen gas can be switched arbitrarily, is used.
• a magnetic stirrer (C-MAG HS10 manufactured by AsOne) was installed in the lower part of the three-necked flask, rotated and stirred at 300 rpm, and while cooling the outer periphery of the three-necked flask with ice water, chlorine gas (manufactured by Fujiox, specified purity). 99.4%) was supplied at 0.059 Pa ⁇ m 3 / sec (when converted to 0 ° C.) for 180 minutes, and an aqueous solution of tetramethylammonium hypochlorous acid (oxidizing agent; equivalent to 3.51% by mass, 0.28 mol /). A mixed solution of L) and tetramethylammonium hydroxide (equivalent to 0.09% by mass, 0.0097 mol / L) was obtained. At this time, the liquid temperature during the reaction was 11 ° C.
• the etching rate of the produced treatment liquid was evaluated every 10 hours by the above-mentioned "method for calculating the etching rate of ruthenium".
• the time during which the obtained etching rate increased or decreased within ⁇ 20% with respect to the etching rate immediately after production was defined as the stabilization time of the etching rate.
• Examples 2 to 23 Comparative Examples 1 to 3>
• the same method as in Example 1 was used so that the bromine-containing compound concentration, the oxidizing agent concentration, the base compound concentration, and the pH had the compositions shown in Tables 1 to 4.
• a treatment solution was prepared and evaluated using a ruthenium film (sample piece) prepared in the same manner as in Example 1.
• the amount of change in film thickness before and after the treatment was less than 5 angstroms, so it was determined that Ru was not etched. Therefore evaluation of RuO 4 gas was not carried out.
• hydrobromic acid (acidic) was used as the bromine-containing compound and mixed with an aqueous solution (alkaline) containing an oxidizing agent and a base compound to prepare an aqueous solution (alkaline) containing hypobromous acid ions.
• an etching of ruthenium like other embodiments, greater etching rate of ruthenium, excellent stability of the etching rate, it was confirmed that high RuO 4 gas suppressing effect.
• Example 24 (Preparation of solution containing oxidizing agent and basic compound)
• a solution (solution A) containing an oxidizing agent and a base compound such that the oxidizing agent concentration, the base compound concentration, and the pH have the compositions shown in Table 6 is prepared.
• a solution (solution A) containing an oxidizing agent and a base compound such that the oxidizing agent concentration, the base compound concentration, and the pH have the compositions shown in Table 6 is prepared.
• Example 25 to 30 follow the compositions, mixing ratios, and mixing methods shown in Table 6 so that the bromine-containing compound concentration, the oxidizing agent concentration, the base compound concentration, and the pH have the compositions shown in Tables 1 to 4.
• a treatment solution was prepared in the same manner as in 24 and evaluated.
• Table reaction time of 6 is the time until the etching rate after mixing liquids A and B is stabilized, i.e. hypobromite ion (BrO -) concentration means the time until the stabilization, hypochlorous It is the time until the concentration change when the brobromate ion concentration is measured every minute is within ⁇ 5%.
• Example 31 Manufacturing of treatment liquid
• Example 32 Manufacturing of treatment liquid
• 100 g of a treatment solution having the composition described in 1 was obtained.
• Example 33 to 35 The obtained treatment liquid was evaluated by the same method as in Example 1.
• an oxidizing agent was produced in the same manner as in Example 1 according to the conditions shown in Table 7, and the bromine-containing compound concentration, the oxidizing agent concentration, the base compound concentration, and the pH were shown in Tables 1 to 4.
• a treatment liquid was prepared in the same manner as in Example 1 so as to have the composition shown. Evaluation was carried out in the same manner as in Example 1.
• Example 36 Manufacturing of tetramethylammonium bromide
• a 2.28% tetramethylammonium hydroxide aqueous solution was prepared by adding 90.88 g of ultrapure water to 9.12 g of a 25% tetramethylammonium hydroxide aqueous solution (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.). Next, 95.7 g of ultrapure water was added to 4.3 g of 47% hydrobromic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) to prepare 2.02% hydrobromic acid.
• Example 37 Treatment solutions having the compositions shown in Tables 1 to 4 were obtained in the same manner as in Example 3. PH of the treatment solution immediately after prepared, the etching rate of ruthenium dioxide, RuO 4 gas yield was evaluated hypobromite ion concentration. The evaluation of the etching rate of ruthenium dioxide was performed by the above-mentioned "method for calculating the etching rate of ruthenium dioxide". The evaluation of the amount of RuO 4 gas generated was carried out by the above-mentioned "quantitative analysis of RuO 4 gas". The evaluation of the hypobromous acid ion concentration was performed by the above-mentioned "method for calculating the hypobromous acid ion concentration".
• the stability evaluation of the etching rate was performed as follows.
• the etching rate of the produced treatment liquid was evaluated every 10 hours by the above-mentioned "method for calculating the etching rate of ruthenium dioxide".
• the time during which the obtained etching rate increased or decreased within ⁇ 20% with respect to the etching rate immediately after production was defined as the stabilization time of the etching rate.
• Example 38 A pH 12 treatment solution containing 0.075 g (0.05 mol / L) of sodium bromate (manufactured by Wako Pure Chemical Industries, Ltd.) and containing the same concentration of bromine-containing compound, oxidizing agent, and base compound as in Example 1 shown in Table 1 was prepared. did. The obtained treatment liquid was evaluated by the same method as in Example 1.
• Example 39 A pH 12 treatment solution containing 0.075 g (0.05 mol / L) of sodium bromate (manufactured by Wako Pure Chemical Industries, Ltd.) and containing the same concentration of bromine-containing compound, oxidizing agent, and base compound as in Example 10 shown in Table 1 was prepared. did. The obtained treatment liquid was evaluated by the same method as in Example 1.
• Tables 1 to 5 show the composition of the treatment liquid and the evaluation results. As shown in Table 5, in Comparative Examples 1 and 2, ruthenium is not etched at all, even in Comparative Example 3 etching was possible, the etching rate and stability are low, the amount of RuO 4 gas because was 2-fold higher tolerance, the etching rate, stability, could not satisfy all RuO 4 gas suppression factor. In contrast, treatment solution of the present embodiment are all well etching rate of ruthenium is higher, excellent stability of the etching rate, further, that the RuO 4 gas suppression effect is high, to satisfy the above three performances It was confirmed. From the results of Examples 24 to 30, it was confirmed that the time required for the etching rate to stabilize in these treatment liquids was as fast as 1 hour or less.
• Example 37 was a treatment solution having the same hypobromous acid ion concentration and the same pH as in Example 3, but it was confirmed that it also had high etching performance with respect to ruthenium dioxide.
• the presence of BrO ⁇ , BrO 3 ⁇ , and Br ⁇ in the treatment liquid improved the stability of the etching rate.

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