JP5148576B2 - Cleaning method - Google Patents

Description

The present invention relates to the cleaning method.

  In fields such as semiconductor devices and MEMS (Micro Electro Mechanical Systems), a fine structure having a fine wall on the surface is manufactured using a lithography technique. Then, the resist that has been formed in the manufacturing process and is no longer necessary is removed using an SPM (sulfuric acid hydrogen peroxide mixture) solution that is a mixed solution of concentrated sulfuric acid and hydrogen peroxide solution (for example, Patent Document 1). reference).

  Here, since the oxidizing substance (for example, peroxomonosulfuric acid) produced by mixing concentrated sulfuric acid and hydrogen peroxide solution reacts with water and decomposes, hydrogen peroxide solution is used to make up for the decomposition. It is necessary to repeat replenishment. Therefore, it is difficult to keep the liquid composition at a constant value. Moreover, there is also a problem that the concentration of sulfuric acid decreases due to an increase in the amount of hydrogen peroxide water mixed, making recycling impossible.

  In view of this, there has been proposed a technique for removing a resist attached to a silicon wafer or the like using an oxidizing substance generated by electrolyzing an aqueous solution of sulfuric acid (see Patent Document 2). According to the technique disclosed in Patent Document 2, an oxidizing substance can be generated from an aqueous solution of sulfuric acid, so that the liquid composition can be stabilized. However, there is a problem that the processing time is longer than when the resist is removed using the SPM solution. Further, even when the resist is stripped using an SPM solution, a reduction in processing time has been required due to a demand for further improvement in productivity.

JP 2007-123330 A JP 2006-111943 A

The present invention provides a cleaning method capable of reducing the processing time.

According to one aspect of the present invention, a step of electrolyzing a sulfuric acid solution having a sulfuric acid concentration of 30 weight percent or more and 70 weight percent or less to produce an oxidizing solution containing an oxidizing substance, and the sulfuric acid concentration of 90 weight percent or more And a step of generating a heat of reaction by mixing the sulfuric acid solution with the oxidizing solution, and a resist having an altered layer formed on the surface by the sulfuric acid solution heated by the reaction heat and the oxidizing solution. comprising a step of washing the cleaned object with the mixing in the step of generating the reaction heat is carried out at the surface of the pre-Symbol cleaned object, the surface of the object to be cleaned, by supplying the sulfuric acid solution, There is provided a cleaning method characterized by repeatedly performing the supply of the oxidizing solution after the supply of the sulfuric acid solution .

ADVANTAGE OF THE INVENTION According to this invention, the cleaning method which can aim at shortening of processing time is provided.

It is a mimetic diagram for illustrating the washing system concerning this embodiment. It is a schematic diagram for illustrating about the production | generation mechanism of an oxidizing substance. It is a graph for demonstrating the influence which the density | concentration of an oxidizing substance and the density | concentration of an inorganic acid have on peeling time. It is a graph for demonstrating the temperature rise by reaction heat. It is a graph for demonstrating the relationship between the frequency | count of supplying sequentially, and peeling time. It is a graph for demonstrating the influence of process temperature (solution temperature). It is a flowchart for demonstrating about the washing | cleaning method. It is a flowchart for demonstrating about the washing | cleaning method which concerns on other embodiment. It is a mimetic diagram for illustrating the washing system concerning other embodiments.

Hereinafter, embodiments of the present invention will be illustrated with reference to the drawings. In addition, in each drawing, the same code | symbol is attached | subjected to the same component and detailed description is abbreviate | omitted suitably.
FIG. 1 is a schematic diagram for illustrating a cleaning system according to the present embodiment.
As shown in FIG. 1, the cleaning system 5 includes a sulfuric acid electrolysis unit 10, an inorganic acid supply unit 50, a cleaning processing unit 12, a solution circulation unit 14, and a diluted sulfuric acid supply unit 15.

  The sulfuric acid electrolysis unit 10 has a function of electrolyzing a sulfuric acid solution to generate an oxidizing substance in the anode chamber 30. Moreover, when the contaminants attached to the object to be cleaned are removed using the solution containing the oxidizing substance, the oxidizing power of the solution containing the oxidizing substance is reduced, but the sulfuric acid electrolysis unit 10 recovers the reduced oxidizing power. It also has a function.

  The sulfuric acid electrolysis unit 10 includes an anode 32, a cathode 42, a diaphragm 20 provided between the anode 32 and the cathode 42, an anode chamber 30 provided between the anode 32 and the diaphragm 20, and a cathode 42. And a cathode chamber 40 provided between the diaphragm 20 and the diaphragm 20.

  An upper end sealing portion 22 is provided at the upper ends of the diaphragm 20, the anode chamber 30 and the cathode chamber 40, and a lower end sealing portion 23 is provided at the lower ends of the diaphragm 20, the anode chamber 30 and the cathode chamber 40. The anode 32 and the cathode 42 are opposed to each other with the diaphragm 20 interposed therebetween. The anode 32 is supported by an anode support 33 and the cathode 42 is supported by a cathode support 43. A DC power supply 26 is connected between the anode 32 and the cathode 42.

  The anode 32 includes a conductive anode substrate 34 and an anode conductive film 35 formed on the surface of the anode substrate 34. The anode substrate 34 is supported on the inner surface of the anode support 33, and the anode conductive film 35 faces the anode chamber 30.

  The cathode 42 includes a cathode base 44 having conductivity and a cathode conductive film 45 formed on the surface of the cathode base 44. The cathode base 44 is supported on the inner surface of the cathode support 43, and the cathode conductive film 45 faces the cathode chamber 40.

  An anode inlet portion 19 is formed on the lower end side of the anode chamber 30, and an anode outlet portion 17 is formed on the upper end side. The anode inlet 19 and the anode outlet 17 are in communication with the anode chamber 30. A cathode inlet portion 18 is formed on the lower end side of the cathode chamber 40, and a cathode outlet portion 16 is formed on the upper end side. The cathode inlet portion 18 and the cathode outlet portion 16 communicate with the cathode chamber 40.

  The inorganic acid supply unit 50 includes a tank 51 that stores a high-concentration inorganic acid solution, a pump 52, and an on-off valve 71. Further, the tank 51, the pump 52, and the on-off valve 71 are connected to the nozzle 61 through the pipe line 53. The high-concentration inorganic acid solution stored in the tank 51 is supplied to the nozzle 61 via the conduit 53 by the operation of the pump 52. That is, the inorganic acid supply unit 50 has a function of supplying a high-concentration inorganic acid solution stored in the tank 51 to the nozzle 61 of the cleaning processing unit 12, and the high-concentration inorganic acid solution supplied to the nozzle 61 is It is supplied to the surface of the cleaning object W. The highly concentrated inorganic acid solution preferably has a dehydrating action. As such a thing, the concentrated sulfuric acid solution whose sulfuric acid concentration is 90 weight percent or more can be illustrated, for example. In addition, a heater can be provided in the tank 51 to control the temperature of the highly concentrated inorganic acid solution.

  In addition, a pipe line and a nozzle (not shown) are provided separately from the pipe line 74 and the nozzle 61, and a high-concentration inorganic acid solution is washed from a pipe system different from a solution containing an oxidizing substance (oxidizing solution). It can also be made to supply.

  The cleaning processing unit 12 uses the solution containing the oxidizing substance (oxidizing solution) obtained in the sulfuric acid electrolysis unit 10 and the high-concentration inorganic acid solution supplied from the inorganic acid supply unit 50 to be cleaned. It has a function of cleaning the object W.

The oxidizing solution obtained in the sulfuric acid electrolysis unit 10 is supplied to the nozzle 61 provided in the cleaning processing unit 12 via the solution circulation unit 14. Further, a high-concentration inorganic acid solution is supplied from the inorganic acid supply unit 50 to the nozzle 61 provided in the cleaning processing unit 12. The oxidizing solution and the high-concentration inorganic acid solution can be sequentially supplied, or the oxidizing solution and the high-concentration inorganic acid solution can be supplied substantially simultaneously.
Alternatively, the oxidizing solution and the high-concentration inorganic acid solution can be mixed and the mixed solution (cleaning solution) can be supplied. When the high-concentration inorganic acid solution supplied from the inorganic acid supply unit 50 and the oxidizing solution supplied from the sulfuric acid electrolysis unit 10 are supplied to the pipeline 74 almost simultaneously, the pipeline 74 is used for both solutions. It becomes a mixing part which mixes.
Further, a tank (not shown) may be provided to mix the oxidizing solution and the high-concentration inorganic acid solution. In this case, a tank (not shown) serves as the mixing unit. If a tank (not shown) is provided, it is possible to buffer the quantitative fluctuation of the mixed liquid (cleaning liquid) and to adjust the composition. In addition, a heater can be provided in a tank or pipe 74 (not shown) to control the temperature of the mixed liquid (cleaning liquid).

The nozzle 61 has a discharge port for discharging an oxidizing solution, a high concentration inorganic acid solution, and a mixed solution (cleaning solution) of the oxidizing solution and the high concentration inorganic acid solution to the cleaning target W. In addition, a rotary table 62 on which the cleaning object W is placed is provided so as to face the discharge port. The rotary table 62 is provided inside the cover 29. Then, the cleaning target W is discharged by discharging the oxidizing solution, the high-concentration inorganic acid solution, and the mixed solution (cleaning liquid) of the oxidizing solution and the high-concentration inorganic acid solution from the nozzle 61 toward the cleaning target W. The above contaminants and unnecessary materials (for example, resist) can be removed in a short time. The removal of contaminants and unnecessary materials (for example, resists) on the cleaning object W in a short time will be described later.
The cleaning processing unit 12 illustrated in FIG. 1 is a so-called single wafer processing method, but may be a batch processing method.

  The oxidizing solution generated in the sulfuric acid electrolysis unit 10 is supplied to the cleaning processing unit 12 from the anode outlet unit 17 through the solution circulation unit 14. The anode outlet part 17 is connected to a tank 28 as a solution holding part via a pipe line 73 provided with an on-off valve 73a. The tank 28 is connected to the nozzle 61 via a pipe line 74, and the oxidizing solution stored in the tank 28 is supplied to the nozzle 61 via the pipe line 74 by the operation of the pump 81. In the pipe line 74, an opening / closing valve 74 a is provided on the discharge side of the pump 81. In the present embodiment, the tank 28, the pump 81, and the like serve as an oxidizing solution supply unit that supplies an oxidizing solution containing an oxidizing substance to the cleaning processing unit 12. In this case, by storing and holding the oxidizing solution in the tank 28, it is possible to buffer the quantitative fluctuation of the oxidizing solution generated in the sulfuric acid electrolysis unit 10. In addition, a heater can be provided in the tank 28 to control the temperature of the oxidizing solution.

  The oxidizing solution discharged from the cleaning processing unit 12 is recovered by the solution circulation unit 14 and can be supplied to the cleaning processing unit 12 again. For example, the oxidizing solution discharged from the cleaning processing unit 12 can pass through the recovery tank 63, the filter 64, the pump 82, and the on-off valve 76 in this order, and can be supplied to the anode inlet 19 of the sulfuric acid electrolysis unit 10. ing. That is, the oxidizing solution is circulated between the sulfuric acid electrolysis unit 10 and the cleaning processing unit 12. In such a case, the oxidizing solution used for the cleaning treatment is supplied to the sulfuric acid electrolysis unit 10 as necessary, and then the sulfuric acid electrolysis unit 10 is electrolyzed to obtain an oxidizing solution containing an oxidizing substance. The oxidizing solution can be supplied to the cleaning processing unit 12 through the tank 28 or the like.

  Here, as necessary, the used oxidizing solution is supplied to the sulfuric acid electrolysis unit 10, and the diluted sulfuric acid supply unit 15 also supplies diluted sulfuric acid to the sulfuric acid electrolysis unit 10 to perform electrolysis. An oxidizing solution can be produced. The oxidizing solution obtained here can be supplied to the cleaning processing unit 12 via the tank 28 or the like. Such reuse of the oxidizing solution can be repeated as much as possible, and in the cleaning process of the cleaning object W, it is possible to reduce the amount of materials (chemicals, etc.) and waste liquid required for generating the oxidizing solution. It becomes.

  Alternatively, the oxidizing solution discharged from the cleaning processing unit 12 passes through the recovery tank 63, the filter 64, the pump 82, and the on-off valve 91 in this order, that is, is supplied to the tank 28 without passing through the sulfuric acid electrolysis unit 10. It can also be possible. Here, it is possible to supply the oxidizing solution from the tank 28 to the cleaning processing unit 12 and perform the cleaning process on the cleaning target W. In such a case, the used oxidizing solution can be reused in the cleaning process. Such reuse of the oxidizing solution can be repeated as much as possible, and the amount of materials (chemicals, etc.) and waste liquid required for generating the oxidizing solution can be reduced.

In addition, the high-concentration inorganic acid solution discharged from the cleaning processing unit 12 and the mixed solution (cleaning solution) of the oxidizing solution and the high-concentration inorganic acid solution can be circulated and reused in the same manner. In particular, when the inorganic acid is sulfuric acid, it becomes a raw material solution of an oxidizing solution, so that the amount of diluted sulfuric acid supplied from the diluted sulfuric acid supply unit 15 (tank 60) can be reduced. In addition, when a problem arises in reuse when the inorganic acid solution and the oxidizing solution are mixed, a recovery tank or an open / close valve (not shown) for the inorganic acid solution is connected to the cleaning processing unit 12 to connect the inorganic acid solution. And the oxidizing solution can be separated and recovered. In this case, if the inorganic acid solution and the oxidizing solution are sequentially supplied, separation and recovery can be performed at the time of each supply. Each can be reused separately, for example, by reprocessing.
The recovery tank 63 is provided with a discharge pipe 75 and a discharge valve 75a, and has a function of discharging contaminants and unnecessary materials (for example, resists) removed by the cleaning processing unit 12 to the outside of the system. Yes. The filter 64 has a function of filtering contaminants and unnecessary substances (for example, a resist) contained in the oxidizing solution, the inorganic acid solution, and the mixed solution (in the cleaning solution) discharged from the cleaning processing unit 12.

  The diluted sulfuric acid supply unit 15 has a function of supplying a diluted sulfuric acid solution to the sulfuric acid electrolysis unit 10 (the anode chamber 30 and the cathode chamber 40). The diluted sulfuric acid supply unit 15 includes a pump 80 that supplies a diluted sulfuric acid solution to the anode chamber 30 and the cathode chamber 40, a tank 60 that stores diluted sulfuric acid, and on-off valves 70 and 72.

  The tank 60 stores a diluted sulfuric acid solution having a sulfuric acid concentration of 30 weight percent or more and 70 weight percent or less. The diluted sulfuric acid solution in the tank 60 passes through the on-off valve 70 by driving of the pump 80 and is supplied to the anode chamber 30 via the pipe line on the downstream side of the on-off valve 76 and the anode inlet 19. Further, the diluted sulfuric acid solution in the tank 60 passes through the on-off valve 72 by driving the pump 80 and is supplied to the cathode chamber 40 via the pipe line 86 on the downstream side of the on-off valve 72 and the cathode inlet portion 18. .

In the present embodiment, since the sulfuric acid concentration of the solution supplied to the cathode side is low, it is possible to prevent the diaphragm 20 from being damaged by the electrolysis of sulfuric acid. That is, in the sulfuric acid electrolysis reaction, water on the cathode side moves to the anode side, the sulfuric acid concentration of the solution on the cathode side increases, and the diaphragm 20 tends to deteriorate. Moreover, when an ion exchange membrane is used for the diaphragm 20, in the concentrated sulfuric acid, the resistance of the ion exchange membrane increases as the water content decreases, and there arises a problem that the cell voltage increases. Therefore, in order to alleviate this problem, it is possible to suppress an increase in resistance by supplying diluted sulfuric acid to the cathode side and supplying water to the ion exchange membrane.
Further, if the concentration of sulfuric acid supplied to the sulfuric acid electrolysis unit 10 is lowered, the production efficiency of the oxidizing substance (for example, peroxomonosulfuric acid, peroxodisulfuric acid) contained in the oxidizing solution can be improved. The improvement in the generation efficiency of the oxidizing substance will be described later.

  The on-off valves 70, 71, 72, 73a, 74a, 75a, 76, 91 described above also have a function of controlling the flow rates of various solutions. The pumps 80, 81, 82 also have a function of controlling the flow rates of various solutions.

  The material of the cover 29 in the anode support 33, the cathode support 43, the cathode outlet part 16, the anode outlet part 17, the cathode inlet part 18, the anode inlet part 19, and the cleaning processing part 12 is, for example, from the viewpoint of chemical resistance. A fluorine resin such as polytetrafluoroethylene may be used.

  In addition, a fluororesin in which a heat insulating material is wound on a pipe for supplying an oxidizing solution, a high-concentration inorganic acid solution, and a mixed solution (cleaning solution) of the oxidizing solution and the high-concentration inorganic acid solution in the cleaning processing unit 12 A tube or the like can be used. This pipe can be provided with an in-line heater made of a fluorine-based resin. Bellows pumps made of fluororesin with heat resistance and chemical resistance are used for pumps that send oxidizing solutions, high-concentration inorganic acid solutions, and mixtures (cleaning solutions) of oxidizing solutions and high-concentration inorganic acid solutions. Can be used.

  For example, quartz can be used as the material of each tank for storing the sulfuric acid solution. Furthermore, an overflow device, a temperature control device, and the like can be appropriately provided in these tanks.

  As the diaphragm 20, for example, a neutral membrane including a porous PTFE membrane such as the product name PORFLON (however, hydrophilized), or a cation exchange membrane such as the product name Nafion, Aciplex, Flemion, etc. Can do. The dimension of the diaphragm 20 is about 50 square centimeters, for example. As the upper end sealing part 22 and the lower end sealing part 23, for example, an O-ring coated with a fluorine-based resin may be used.

  For example, p-type silicon or a valve metal such as niobium can be used as the material of the anode conductive substrate 34. Here, the valve metal means that the metal surface is uniformly covered with the oxide film by anodic oxidation and has excellent corrosion resistance. For the cathode conductive substrate 44, for example, n-type silicon can be used.

  As a material for the anode conductive film 35 and the cathode conductive film 45, for example, glassy carbon can be used. When a solution having a relatively high sulfuric acid concentration is supplied, a conductive diamond film is preferably used from the viewpoint of durability.

  For both the anode and the cathode, the conductive film and the substrate may be the same material. For example, when glassy carbon is used for the cathode substrate or when a conductive diamond free-standing film is used for the anode substrate, the substrate itself becomes a conductive film having electrocatalytic properties and can contribute to the electrolytic reaction.

  Although diamond has chemically, mechanically and thermally stable properties, it has been difficult to use in electrochemical systems due to its poor electrical conductivity. However, a conductive diamond film can be obtained by forming a film while supplying boron gas or nitrogen gas using a hot filament-CVD (HF-CVD) method. This conductive diamond film has a wide “potential window” of, for example, 3 to 5 volts, and an electrical resistance of, for example, 5 to 100 milliohm centimeters.

  Here, the “potential window” is the minimum potential (1.2 volts or more) required for electrolysis of water. This “potential window” varies depending on the material. When electrolysis is performed at a potential in the “potential window” using a material with a wide “potential window”, the electrolytic reaction having a redox potential in the “potential window” proceeds in preference to the electrolysis of water. In some cases, an oxidation reaction or a reduction reaction of a substance that is difficult to be electrolyzed proceeds preferentially. Therefore, by using such conductive diamond, it becomes possible to decompose and synthesize substances that were impossible with conventional electrochemical reactions.

  In the HF-CVD method, a source gas is supplied to a tungsten filament in a high temperature state to be decomposed. Then, radicals necessary for film growth are formed. Thereafter, a film is formed by reacting radicals diffused on the substrate surface with another reactive gas on a desired substrate.

Next, the generation mechanism of the oxidizing substance in the sulfuric acid electrolysis unit 10 will be illustrated.
FIG. 2 is a schematic diagram for illustrating the generation mechanism of the oxidizing substance. 2A is a schematic side sectional view of the sulfuric acid electrolysis unit, and FIG. 2B is a schematic diagram showing a cross section taken along line AA in FIG. 2A.
As shown in FIGS. 2A and 2B, the anode 32 and the cathode 42 are provided to face each other with the diaphragm 20 interposed therebetween. The anode 32 is supported by the anode support 33 with the anode conductive film 35 facing the anode chamber 30. The cathode 42 is supported by a cathode support 43 with the cathode conductive film 45 facing the cathode chamber 40. Electrolytic unit casings 24 are provided at both ends of the diaphragm 20, the anode support 33, and the cathode support 43, respectively.

  For example, a 70 weight percent sulfuric acid solution (diluted sulfuric acid solution) is supplied from the tank 60 to the anode chamber 30 via the anode inlet 19. For example, a 70 weight percent sulfuric acid solution (diluted sulfuric acid solution) is also supplied from the tank 60 to the cathode chamber 40 via the cathode inlet 18.

ここで、化学式２、化学式３における水（Ｈ_２Ｏ）は、７０重量パーセントの硫酸溶液に含まれる３０パーセントの水である。そして、陽極室３０では、化学式２の反応によりペルオキソ一硫酸イオン（ＨＳＯ_５ ⁻）が生成する。また、化学式１及び化学式３の素反応により、化学式４に表すような全反応が生じて、ペルオキソ一硫酸イオン（ＨＳＯ_５ ⁻）と硫酸が生成する反応も生じる。このペルオキソ一硫酸は、硫酸よりも強力な洗浄力を有する。

あるいは、化学式１及び化学式３の素反応から、化学式５に表すように、過酸化水素（Ｈ_２Ｏ_２）が生成した後、化学式４のペルオキソ一硫酸イオン（ＨＳＯ_５ ⁻）が生成される場合もある。また、化学式１の反応により、ペルオキソ二硫酸（Ｈ_２Ｓ_２Ｏ_８）が生成される場合もある。化学式４、化学式５は、化学式１からの二次反応を表す。

また、陰極室４０では、化学式６に表すように、水素ガスが生成される。これは、陽極で生じた水素イオン（Ｈ^＋）が、隔膜２０を介して陰極に移動し、電気分解反応が生じるためである。水素ガスは、陰極出口部１６を介して陰極室４０から排出される。

本実施の形態においては、化学式７に表すように、硫酸溶液を電気分解することで、例えば、ペルオキソ一硫酸（Ｈ_２ＳＯ_５）、ペルオキソ二硫酸（Ｈ_２Ｓ_２Ｏ_８）などの酸化性物質を得ることができるので、それを含む酸化性溶液が得られる。なお、副生成物としては水素ガスが生成されるが、この水素ガスはレジストなどの剥離には影響しない。

ペルオキソ一硫酸を用いた場合、レジストなどの有機物との反応速度が速いので、比較的除去すべき量の多いレジスト剥離であっても短時間で済ますことができる。また、ペルオキソ一硫酸を用いる場合には、低温で剥離させることができるので、温度立ち上げなどの調節時間が不要である。また、ペルオキソ一硫酸を安定して多量に生成することができるので、低温においても除去対象物との反応速度を上げることができる。 When a positive voltage is applied to the anode 32 and a negative voltage is applied to the cathode 42, an electrolysis reaction occurs in each of the anode chamber 30 and the cathode chamber 40. In the anode chamber 30, reactions represented by Chemical Formula 1, Chemical Formula 2 and Chemical Formula 3 occur.

Here, water (H ₂ O) in Chemical Formula 2 and Chemical Formula 3 is 30 percent water contained in a 70 weight percent sulfuric acid solution. In the anode chamber 30, peroxomonosulfate ions (HSO ₅ ⁻ ) are generated by the reaction of Chemical Formula 2. In addition, the elementary reactions of Chemical Formula 1 and Chemical Formula 3 cause the entire reaction as shown in Chemical Formula 4 and the reaction of generating peroxomonosulfate ions (HSO ₅ ⁻ ) and sulfuric acid. This peroxomonosulfuric acid has a stronger detergency than sulfuric acid.

Alternatively, as shown in Chemical Formula 5, after the hydrogen peroxide (H ₂ O ₂ ) is generated from the elementary reaction of Chemical Formula 1 and Chemical Formula 3, the peroxomonosulfate ion (HSO ₅ ⁻ ) of Chemical Formula 4 is generated. There is also. In addition, peroxodisulfuric acid (H ₂ S ₂ O ₈ ) may be generated by the reaction of Chemical Formula 1. Chemical formula 4 and chemical formula 5 represent secondary reactions from chemical formula 1.

In the cathode chamber 40, hydrogen gas is generated as represented by Chemical Formula 6. This is because hydrogen ions (H ⁺ ) generated at the anode move to the cathode through the diaphragm 20 and an electrolysis reaction occurs. Hydrogen gas is discharged from the cathode chamber 40 through the cathode outlet portion 16.

In this embodiment, as shown in Chemical Formula 7, by oxidizing the sulfuric acid solution, for example, oxidizing properties such as peroxomonosulfuric acid (H ₂ SO ₅ ), peroxodisulfuric acid (H ₂ S ₂ O ₈ ), etc. Since the substance can be obtained, an oxidizing solution containing it can be obtained. In addition, although hydrogen gas is produced | generated as a by-product, this hydrogen gas does not affect peeling of a resist etc.

When peroxomonosulfuric acid is used, the reaction rate with organic substances such as resist is high, so that even a relatively large amount of resist to be removed can be removed in a short time. When peroxomonosulfuric acid is used, it can be peeled off at a low temperature, so that adjustment time such as temperature rise is unnecessary. Moreover, since peroxomonosulfuric acid can be stably produced in a large amount, the reaction rate with the removal target can be increased even at low temperatures.

  Here, in order to shorten the processing time and improve the production efficiency, the amount of the oxidizing substance may be increased. In this case, if the size of the apparatus is increased, the applied power is increased, or the amount of dilute sulfuric acid solution is increased, the amount of the generated oxidizing substance can be increased. However, doing so will also increase production costs and environmental impact. Therefore, it is necessary to improve the electrolytic efficiency and efficiently generate the oxidizing substance.

According to the knowledge obtained by the present inventors, when the electrolysis parameters (for example, the amount of electricity, the flow rate, the temperature, etc.) are made constant, the more the oxidizing substance is generated, the lower the sulfuric acid concentration during electrolysis. it can. Therefore, if the concentration of sulfuric acid supplied to the sulfuric acid electrolysis unit 10 is lowered, the production efficiency of oxidizing substances (for example, peroxomonosulfuric acid and peroxodisulfuric acid) contained in the oxidizing solution can be improved.
However, according to other knowledge obtained by the present inventors, the treatment time becomes longer as the concentration of inorganic acid such as sulfuric acid is lower in the removal and removal of organic substances such as resist.
FIG. 3 is a graph for illustrating the influence of the concentration of the oxidizing substance and the concentration of the inorganic acid on the peeling time. The horizontal axis represents the concentration of the oxidizing substance, and the vertical axis represents the peeling time. In the figure, B1 is 70% by weight of sulfuric acid, B2 is 80% by weight of sulfuric acid, B3 is 85% by weight of sulfuric acid, B4 is 90% by weight of sulfuric acid, B5 Is when the sulfuric acid concentration is 95 weight percent.
As can be seen from FIG. 3, the lower the concentration of sulfuric acid, the more oxidizing substances can be generated, and the concentration of oxidizing substances increases. In the case where the sulfuric acid concentration is the same, the stripping time can be shortened as the concentration of the oxidizing substance is higher (as the amount of the oxidizing substance is larger).
However, in comparison with those having different sulfuric acid concentrations, the higher the sulfuric acid concentration, the shorter the peeling time.

  That is, the lower the concentration of sulfuric acid, the more oxidizing material can be produced at the stage of producing the oxidizing substance, but the sulfuric acid concentration can be increased even if the amount of oxidizing substance is the same at the stage of stripping. The higher the value, the shorter the peeling time.

Therefore, in the present embodiment, a dilute sulfuric acid solution having a sulfuric acid concentration of 30 weight percent or more and 70 weight percent or less is supplied to the sulfuric acid electrolysis unit 10. In addition, a high-concentration inorganic acid solution (for example, a concentrated sulfuric acid solution having a sulfuric acid concentration of 90 weight percent or more) is supplied to the surface of the cleaning object W without passing through the sulfuric acid electrolysis unit 10.
Therefore, the electrolytic efficiency in the sulfuric acid electrolysis part 10 can be improved and more oxidizing substances can be generated. In addition, a high concentration inorganic acid can be supplied to the surface of the cleaning object W without affecting the electrolysis efficiency in the sulfuric acid electrolysis unit 10. As a result, a solution having a high concentration of an inorganic acid such as sulfuric acid and a large amount of an oxidizing substance can be supplied to the surface of the cleaning object W, so that the processing time can be greatly shortened.

  Here, according to an experiment conducted by the present inventors, a diluted sulfuric acid solution having a sulfuric acid concentration of 70 weight percent is supplied to the sulfuric acid electrolysis unit 10 to generate an oxidizing solution, which is applied to the surface of the cleaning object W. When the resist was stripped by supplying, the stripping time was about 120 seconds. On the other hand, a diluted sulfuric acid solution having a sulfuric acid concentration of 70 weight percent is supplied to the sulfuric acid electrolysis unit 10 to produce an oxidizing solution, and when this is supplied to the surface of the cleaning object W, a concentrated sulfuric acid concentration of 98 weight percent is obtained. When sulfuric acid was added to form an oxidizing solution having a sulfuric acid concentration of 82 weight percent, the stripping time could be greatly reduced to about 20 seconds.

  In addition, a semiconductor device for high-speed operation is manufactured by implanting a high dose of impurities, but if a high dose of impurities is implanted, an altered layer is formed on the resist surface. The resist having such a deteriorated layer is difficult to peel off, and there is a problem that a desired peeling margin cannot be obtained.

  According to the present embodiment, since a highly concentrated inorganic acid and an oxidizing solution containing a large amount of an oxidizing substance can be supplied to the surface of the cleaning object W, even a resist having an altered layer formed can be used. The peelability can be improved.

Moreover, the reaction heat at the time of mixing a high concentration inorganic acid solution and the oxidizing solution which is also a low concentration inorganic acid solution can also be utilized. If the temperature is increased, the reactivity of the oxidizing substance contained in the oxidizing solution can be increased, so that the processing time can be shortened.
However, if the solution temperature in the sulfuric acid electrolysis unit 10 or the inorganic acid supply unit 50 is increased, the heat-resistant temperature and strength of each component (for example, pipes, opening / closing valves, pumps, tanks, covers of the cleaning processing unit, etc.) May be a problem. In order to improve chemical resistance, a portion that comes into contact with a high concentration inorganic acid solution or oxidizing solution is often formed of, for example, a fluorine resin. In such a case, if the temperature is too high, the required strength may not be obtained.

  According to the present embodiment, before being supplied to the cleaning target W or on the cleaning target W, the high-concentration inorganic acid solution and the oxidizing solution that is also the low-concentration inorganic acid solution are mixed. Heat of reaction can be generated. Therefore, while the temperature rise of each component can be suppressed, the reactivity of an oxidizing substance can be improved by raising the temperature of the mixed liquid.

  FIG. 4 is a graph for illustrating temperature increase due to reaction heat. The vertical axis represents the temperature of the mixed liquid, and the horizontal axis represents the concentration of the mixed liquid. Further, the temperature of the high-concentration inorganic acid solution and the low-concentration inorganic acid solution before mixing (the concentrated sulfuric acid solution and the diluted sulfuric acid solution illustrated in FIG. 4) are both 88 ° C. C1 in the figure represents the case where a diluted sulfuric acid solution having a sulfuric acid concentration of 30 weight percent and a concentrated sulfuric acid solution having a sulfuric acid concentration of 98 weight percent are mixed. C2 in the figure represents a case where a diluted sulfuric acid solution having a sulfuric acid concentration of 50 weight percent and a concentrated sulfuric acid solution having a sulfuric acid concentration of 98 weight percent are mixed. C3 in the figure represents a case where a diluted sulfuric acid solution having a sulfuric acid concentration of 70 weight percent and a concentrated sulfuric acid solution having a sulfuric acid concentration of 98 weight percent are mixed.

As can be seen from FIG. 4, reaction heat can be generated by mixing inorganic acids (sulfuric acid) having different concentrations, and by using this, the temperature of the mixed liquid can be raised. Also, the temperature rise is increased as there is a difference in the concentration of the liquid to be mixed or the mixing ratio is such that the mixed liquid is diluted (the mixing ratio is such that the concentration of the mixed liquid is decreased). Can be increased.
Therefore, it is possible to adjust the conditions such that optimum peeling can be performed by appropriately selecting the concentration of the liquid to be mixed, the mixing ratio, the amount and reactivity of the oxidizing substance, the temperature of the solution before mixing, and the like.

In the case described above, a high-concentration inorganic acid solution is mixed with an oxidizing solution that is also a low-concentration inorganic acid solution. Next, a high-concentration inorganic acid solution and an oxidizing solution are sequentially added. The case of supplying is illustrated.
Table 1 compares the time until the resist is peeled when the test piece having a resist formed on the surface is immersed in a highly concentrated inorganic acid solution and then the test piece is immersed in an oxidizing solution. Is. The high concentration inorganic acid solution was a concentrated sulfuric acid solution having a sulfuric acid concentration of 98 weight percent. The oxidizing solution was generated by electrolyzing a diluted sulfuric acid solution having a sulfuric acid concentration of 70 weight percent. Moreover, the temperature of the high concentration inorganic acid solution and the oxidizing solution is set to about 100 to 110 ° C. as an example.

表１に示すように、高濃度の無機酸溶液（硫酸濃度が９８重量パーセントの濃硫酸溶液）に浸漬させない場合は（サンプルＮＯ．１の場合）、レジストが剥離されるまでに１２０秒かかる。これに対し、高濃度の無機酸溶液（硫酸濃度が９８重量パーセントの濃硫酸溶液）に浸漬させた場合は（サンプルＮＯ．２〜４の場合）、レジストが剥離されるまでに２０秒程度しかかからず処理時間（剥離時間）の大幅な短縮が図れることがわかる。また、高濃度の無機酸溶液（硫酸濃度が９８重量パーセントの濃硫酸溶液）に浸漬させる時間は短くても、レジストが剥離されるまでの時間には大きな影響がないこともわかる。

As shown in Table 1, when not immersed in a highly concentrated inorganic acid solution (concentrated sulfuric acid solution having a sulfuric acid concentration of 98 weight percent) (in the case of sample No. 1), it takes 120 seconds for the resist to be stripped. In contrast, when immersed in a high-concentration inorganic acid solution (concentrated sulfuric acid solution having a sulfuric acid concentration of 98 weight percent) (in the case of sample Nos. 2 to 4), it takes only about 20 seconds until the resist is peeled off. It can be seen that the processing time (peeling time) can be greatly shortened. It can also be seen that even if the time for dipping in a high-concentration inorganic acid solution (concentrated sulfuric acid solution having a sulfuric acid concentration of 98 weight percent) is short, the time until the resist is stripped is not significantly affected.

  FIG. 5 is a graph for illustrating the relationship between the number of times of sequential supply and the peeling time. The vertical axis represents the sample NO, and the horizontal axis represents the time until the resist formed on the surface of the test piece is peeled (peeling time). Further, D1 in the figure represents a case where the sulfuric acid concentration is immersed in a concentrated sulfuric acid solution having a 98 weight percent sulfuric acid, and D2 is immersed in an oxidizing solution generated by electrolyzing a diluted sulfuric acid solution having a sulfuric acid concentration of 70 weight percent. This represents the case where Moreover, the temperature of the concentrated sulfuric acid solution with a sulfuric acid concentration of 98 weight percent and an oxidizing solution was about 100-110 degreeC as an example.

Sample No. No. 10 is a case where immersion in a concentrated sulfuric acid solution having a sulfuric acid concentration of 98 weight percent for 1 second was performed once (part D1). In this case, it is understood that it takes about 16 seconds for the resist to be peeled off.
Sample No. 11 is a case where immersion in a concentrated sulfuric acid solution having a sulfuric acid concentration of 98 weight percent for 1 second (part D1) and immersion in an oxidizing solution for 4 seconds (part D2) were sequentially performed. In this case, the resist was peeled off when the sulfuric acid concentration was immersed twice in the concentrated sulfuric acid solution with 98 weight percent and the oxidizing solution was immersed twice. It can be seen that the time until the resist is stripped is 10 seconds, and the processing time can be shortened.

  Sample No. No. 12 is a case where immersion in a concentrated sulfuric acid solution having a sulfuric acid concentration of 98 weight percent for 1 second (part D1) and immersion in an oxidizing solution for 1 second (part D2) were sequentially performed. In this case, the resist was peeled off when the number of immersions in the 98 weight percent concentrated sulfuric acid solution was four and the number of immersions in the oxidizing solution was four. The time until the resist is peeled is 8 seconds, and it can be seen that the processing time can be further shortened.

  As described above, the processing time can be shortened by increasing the number of times of immersion and sequentially repeating the immersion. Further, as illustrated in Table 1, even if the immersion time is short, the time until the resist is peeled off is not greatly affected. Therefore, the treatment time can be shortened by repeating soaking for a relatively short time.

FIG. 6 is a graph for illustrating the influence of the processing temperature (solution temperature). The vertical axis represents the sample NO, and the horizontal axis represents the time until the resist formed on the surface of the test piece is peeled (peeling time). Further, E1 in the figure represents the case where the sulfuric acid concentration is immersed in a concentrated sulfuric acid solution having a 98 weight percent sulfuric acid, and E2 is immersed in an oxidizing solution generated by electrolyzing a diluted sulfuric acid solution having a sulfuric acid concentration of 70 weight percent. This represents the case where
Sample No. 20 is a case where the temperature of the concentrated sulfuric acid solution having a sulfuric acid concentration of 98 weight percent is set to room temperature and the temperature of the oxidizing solution is set to 75 ° C. In this case, the resist is peeled off by immersing in a concentrated sulfuric acid solution having a sulfuric acid concentration of 98 weight percent for 5 seconds and then in an oxidizing solution. In this case, the time until the resist peeled was 520 seconds.

  Sample No. 21 is the case where the temperature of the concentrated sulfuric acid solution having a sulfuric acid concentration of 98 weight percent is 75 ° C. and the temperature of the oxidizing solution is 75 ° C. In this case, the resist is peeled off by immersing in a concentrated sulfuric acid solution having a sulfuric acid concentration of 98 weight percent for 5 seconds and then in an oxidizing solution. In this case, the time until the resist peeled was 360 seconds.

  Sample No. No. 22 is a case where the temperature of the concentrated sulfuric acid solution having a sulfuric acid concentration of 98 weight percent is 100 ° C., and the temperature of the oxidizing solution is 75 ° C. In this case, the resist is peeled off by immersing in a concentrated sulfuric acid solution having a sulfuric acid concentration of 98 weight percent for 5 seconds and then in an oxidizing solution. In this case, the time until the resist peeled was 80 seconds.

  Sample No. No. 23 is a case where the temperature of the concentrated sulfuric acid solution having a sulfuric acid concentration of 98 weight percent is 100 ° C. and the temperature of the oxidizing solution is 100 ° C. In this case, the resist is peeled off by immersing in a concentrated sulfuric acid solution having a sulfuric acid concentration of 98 weight percent for 5 seconds and then in an oxidizing solution. In this case, the time until the resist peeled was 20 seconds.

In this way, the processing time can be shortened as the processing temperature (solution temperature) is increased. However, when the temperature becomes too high, each component of the cleaning system (for example, pipes of each part, on-off valves, pumps, tanks, The heat-resistant temperature and strength of the cleaning processing unit cover, etc.) may become a problem. In order to improve chemical resistance, a portion that comes into contact with a high concentration inorganic acid solution or oxidizing solution is often formed of, for example, a fluorine resin. In such a case, if the temperature is too high, the required strength may not be obtained.
Therefore, considering the shortening of the processing time and the heat-resistant temperature and strength on the cleaning system side, the temperature of the highly concentrated inorganic acid solution and oxidizing solution is preferably 100 ° C. or higher and 110 ° C. or lower. In this case, if the reaction heat described above is used, the treatment temperature (solution temperature) can be further increased while reducing the thermal burden on the cleaning system. If reaction heat is used, the processing temperature (solution temperature) can be set to 100 ° C. or higher and 150 ° C. or lower.

Next, the cleaning method according to this embodiment will be illustrated.
FIG. 7 is a flowchart for illustrating the cleaning method.
First, an oxidized solution containing an oxidizing substance (for example, peroxomonosulfuric acid or peroxodisulfuric acid) is generated by electrolyzing the diluted sulfuric acid solution (step S1-1). In this case, if the sulfuric acid concentration of the diluted sulfuric acid solution is 30 weight percent or more and 70 weight percent or less, an oxidizing substance can be efficiently generated.

  Next, the temperature of the generated oxidizing solution is adjusted (step S1-2). Although this temperature adjustment is not necessarily required, it is preferable to adjust the temperature of the solution to be 100 ° C. or higher and 110 ° C. or lower as described above. It should be noted that the temperature adjustment can be performed on any of the generated oxidizing solution, the oxidizing solution generated (electrolysis), or the diluted sulfuric acid solution supplied for electrolysis.

  Further, the temperature of the high concentration inorganic acid solution is adjusted (step S2). Examples of the high concentration inorganic acid solution include an inorganic acid solution having an inorganic acid concentration of 90 weight percent or more. For example, a concentrated sulfuric acid solution having a sulfuric acid concentration of 90 weight percent or more can be used. Although this temperature adjustment is not always necessary, it is preferable to adjust the temperature to be 100 ° C. or higher and 110 ° C. or lower as described above.

Next, a high-concentration inorganic acid solution and an oxidizing solution are supplied to the surface of the cleaning object W individually, sequentially or substantially simultaneously (step S3). The supply may be performed for each cleaning object W from a nozzle or the like, or may be sequentially immersed in a high-concentration inorganic acid solution and an oxidizing solution. In addition, for example, the high-concentration inorganic acid solution and the oxidizing solution may be supplied separately or sequentially from separate piping systems. Also, a so-called single wafer processing method, batch processing method, or the like can be used.
Further, the surface of the cleaning object W is generated by supplying a high-concentration inorganic acid solution (for example, concentrated sulfuric acid) and an oxidizing solution containing an oxidizing substance (for example, electrolysis of diluted sulfuric acid). If the treatment performed by supplying (electrolytic sulfuric acid) is repeated a predetermined number of times, the treatment time (peeling time) can be further shortened.
In this case, it is not necessary to provide a step of supplying the rinse liquid to the surface of the cleaning object W between the supply of the high-concentration inorganic acid solution and the supply of the oxidizing solution. Therefore, the manufacturing process can be simplified and the processing time (peeling time) can be shortened.

FIG. 8 is a flowchart for illustrating a cleaning method according to another embodiment.
In the present embodiment, an oxidizing solution and a high-concentration inorganic acid solution are mixed and supplied to the surface of the cleaning object W.

  First, an oxidized solution containing an oxidizing substance (for example, peroxomonosulfuric acid or peroxodisulfuric acid) is generated by electrolyzing the diluted sulfuric acid solution (step S10). In this case, when the sulfuric acid concentration of the diluted sulfuric acid is set to 30% by weight or more and 70% by weight or less, the oxidizing substance can be efficiently generated.

  Next, the oxidizing solution and the high-concentration inorganic acid solution are mixed to generate a cleaning liquid (step S11). At this time, the concentration of the inorganic acid and the amount of the oxidizing substance in the cleaning liquid are appropriately adjusted. Examples of the high concentration inorganic acid solution include an inorganic acid solution having an inorganic acid concentration of 90 weight percent or more. For example, a concentrated sulfuric acid solution having a sulfuric acid concentration of 90 weight percent or more can be used.

  Next, the temperature of the generated cleaning liquid is adjusted (step S12). Although this temperature adjustment is not necessarily required, it is preferable to adjust the temperature of the cleaning liquid to be 100 ° C. or higher and 110 ° C. or lower as described above. In addition, temperature adjustment can also be performed with respect to the oxidizing solution before mixing and a high concentration inorganic acid solution.

  Next, a cleaning liquid (a mixed liquid of a high-concentration inorganic acid solution and an oxidizing solution) is supplied to the surface of the cleaning object W (step S13). The supply may be performed for each cleaning object W from a nozzle or the like, or may be immersed in the cleaning liquid. Also, a so-called single wafer processing method, batch processing method, or the like can be used.

As illustrated in FIGS. 7 and 8, in the present embodiment, since the diluted sulfuric acid solution is electrolyzed, the electrolysis efficiency is high, and more oxidizing substances can be efficiently generated. In this case, since the high-concentration inorganic acid solution and the oxidizing solution are mixed after the generation of the oxidizing substance (after the electrolysis), the electrolytic efficiency is not affected.
Moreover, it can be set as the process in the washing | cleaning liquid with a high density | concentration of an inorganic acid by the high concentration inorganic acid solution, or the washing | cleaning target object W surface with a high density | concentration of an inorganic acid.
Therefore, the treatment (cleaning) with a high concentration of inorganic acid such as sulfuric acid and a large amount of the oxidizable substance can be performed, so that the treatment time (peeling time) can be greatly shortened.

  In addition, a semiconductor device for high-speed operation is manufactured by implanting a high dose of impurities. However, if a high dose of impurities is implanted, an altered layer is formed on the surface of the resist. The resist having such a deteriorated layer is difficult to peel off, and there is a problem that a desired peeling margin cannot be obtained.

  According to the present embodiment, since a solution containing a large amount of high-concentration inorganic acid and oxidizing substance can be supplied to the surface of the object to be cleaned W, even if the resist has an altered layer, its peelability Can be improved.

  Also, before being supplied to the cleaning object W or on the cleaning object W, a reaction heat is generated by mixing a high concentration inorganic acid solution and an oxidizing solution which is also a low concentration inorganic acid solution. Can do. Therefore, the temperature rise of each component of the cleaning system can be suppressed, and the reactivity of the oxidizing substance can be increased by increasing the temperature of the mixed liquid. As a result, the processing time (peeling time) can be further shortened.

Next, a method for manufacturing the microstructure according to this embodiment is illustrated.
As a manufacturing method of the fine structure, for example, a manufacturing method of a semiconductor device can be exemplified. Here, in the manufacturing process of a semiconductor device, a process of forming a pattern on a substrate (wafer) surface by film formation, resist coating, exposure, development, etching, resist removal, etc. in a so-called previous process, an inspection process, a cleaning process, and a heat treatment There are a process, an impurity introduction process, a diffusion process, a planarization process, and the like. In the so-called post-process, there are an assembly process such as dicing, mounting, bonding, and encapsulation, and a function and reliability inspection process.

  In this case, for example, the resist removal (peeling) can be quickly performed by using the above-described cleaning method or cleaning system in the resist removal step. It should be noted that since the techniques other than the cleaning method and the cleaning system according to the present embodiment described above can apply known techniques in each step, detailed description thereof will be omitted.

  Moreover, although the manufacturing method of the semiconductor device was illustrated as an example of the manufacturing method of a fine structure, it is not necessarily limited to this. For example, the present invention can be applied to fields such as liquid crystal display devices, phase shift masks, micromachines in the MEMS field, and precision optical components.

  Further, in the above-described cleaning system, the solution circulation structure is not necessarily provided. As shown in FIG. 9, the used solution used in the cleaning processing unit 12 is put in the collection tank 63 together with contaminants. Once recovered, it may be discharged out of the system via the discharge pipe 75.

  Moreover, it can be similarly used not only for removing resists made of organic substances but also for removing metal impurities, particles, and dry etching residues.

  Moreover, you may provide the robot for conveying a washing | cleaning target object. Further, the tank 60 for storing the diluted sulfuric acid solution and the tank 51 for storing the high-concentration inorganic acid solution may be connected to a factory line so that the solution is automatically replenished. Moreover, you may provide the rinse tank which rinses the washing | cleaning target object which removed the contaminant. This rinse tank can be provided with an overflow control device or a temperature control device using an inline heater. Quartz may be used as a material for the rinsing tank.

  However, a rinsing liquid is provided between the supply of the high-concentration inorganic acid solution (for example, concentrated sulfuric acid) and the supply of the oxidizing solution (for example, electrolytic sulfuric acid generated by electrolysis of diluted sulfuric acid) to the surface of the object to be cleaned. There is no need to provide a process for supplying to. A treatment performed by supplying a highly concentrated inorganic acid solution (for example, concentrated sulfuric acid) to the object W to be cleaned, and an oxidizing solution containing an oxidizing substance (for example, electrolytic sulfuric acid generated by electrolysis of diluted sulfuric acid) What is necessary is just to repeat the process performed by supplying a predetermined number of times. Therefore, the manufacturing process can be simplified and the processing time (peeling time) can be shortened.

The embodiment of the present invention has been illustrated above. However, the present invention is not limited to these descriptions.
As long as the features of the present invention are provided, those skilled in the art appropriately modified the design of the above-described embodiments are also included in the scope of the present invention.

For example, the shape, size, material, arrangement, and the like of each element included in the above-described cleaning system are not limited to those illustrated, but can be changed as appropriate.
Moreover, each element with which each embodiment mentioned above is combined can be combined as much as possible, and what combined these is also included in the scope of the present invention as long as the characteristics of the present invention are included.

  5 cleaning system, 10 sulfuric acid electrolysis unit, 12 cleaning processing unit, 14 solution circulation unit, 15 diluted sulfuric acid supply unit, 20 diaphragm, 30 anode chamber, 32 anode, 40 cathode chamber, 42 cathode, 50 inorganic acid supply unit

Claims (1)

Electrolyzing a sulfuric acid solution having a sulfuric acid concentration of 30 weight percent or more and 70 weight percent or less to produce an oxidizing solution containing an oxidizing substance;
A step of mixing a sulfuric acid solution having a sulfuric acid concentration of 90 weight percent or more and the oxidizing solution to generate heat of reaction;
A step of cleaning an object to be cleaned having a resist having a deteriorated layer formed on the surface with the sulfuric acid solution and the oxidizing solution heated by the reaction heat;
With
Mixed in the step of generating the reaction heat is carried out at the surface of the pre-Symbol cleaned object,
A cleaning method comprising: repeatedly supplying the sulfuric acid solution to the surface of the object to be cleaned, and supplying the oxidizing solution after supplying the sulfuric acid solution .

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