JP3910190B2 - Cleaning device - Google Patents

Description

The present invention relates to a cleaning apparatus for cleaning a semiconductor substrate or the like.

  As a method for cleaning a semiconductor substrate, an RCA cleaning method using an SC-1 solution of hydrogen peroxide and ammonium hydroxide and an SC-2 solution of hydrogen peroxide and dilute hydrochloric acid is known. In this RCA cleaning method, a semiconductor substrate is immersed in a cleaning bath for cleaning, so that when the semiconductor substrate is cleaned, metal impurities in the cleaning liquid adhere to the surface of the semiconductor substrate or are removed once from the surface of the semiconductor substrate. There was a problem that impurities reattached. In recent years, there have been movements for increasing the diameter of semiconductor substrates, making fine processes, and introducing new wiring materials, and a review of conventional RCA cleaning methods is being considered.

  In addition, from the viewpoint of reducing the burden on the global environment, it is necessary to review the conventional cleaning process that uses a large amount of chemicals and ultrapure water. As a method for solving these problems, a single semiconductor substrate is used. There is a growing interest in cleaning methods using a single wafer cleaning method. In order to remove particles, metal contamination, and organic contamination on the semiconductor substrate in a short cleaning time, a cleaning device using functional water for cleaning such as ozone water has been developed and used.

  The ozone water used in the semiconductor device manufacturing process is required to have a high concentration of ozone dissolved in water, a high degree of cleanness, and no impurities. Usually, ozone water is generated by bringing ozone gas generated by electrolysis of pure water or an oxygen gas discharge method into contact with pure water or ultrapure water to dissolve ozone in the ozone gas in pure water. The use of high-purity oxygen gas as the raw material for producing ozone gas and the use of pure water or ultrapure water as the raw material for producing ozone water are none other than eliminating impurities from ozone gas and reducing impurities in ozone water.

  However, the solubility of ozone in ultrapure water is low. For example, when used for single wafer cleaning, it is about 30 ppm, and since the amount of dissolved ozone is small, satisfactory cleaning power cannot be obtained, the range of use is limited, and quick cleaning is difficult. It has become.

  Therefore, how to increase the solubility of ozone is a major issue. Further, since ozone is relatively unstable in pure water, there is an inherent problem that ozone dissolved in pure water is easily decomposed and it is difficult to maintain the concentration. Although depending on the purity of ultrapure water, which is raw water, it has been confirmed that the concentration of ozone water of 10 ppm or more drops to 2 ppm or less when 20 m is passed through the pipe. For this reason, in ozone water cleaning, it is necessary to arrange ozone water supply equipment as close as possible to the cleaning machine. In order to obtain a stable concentration, ozone water is continuously supplied regardless of whether it is used or not. When not used, blow water is discharged without touching the semiconductor substrate.

  As described above, ozone water has low solubility in pure water. Moreover, it has been confirmed that the solubility is further lowered by simply passing the pipe. Therefore, it is an issue to make ozone water with high solubility so that the solubility does not decrease even through piping.

The present invention has been made by paying attention to the above circumstances, and an object of the present invention is to provide a cleaning device capable of ejecting water vapor onto a substrate and removing fine particles, organic matter, metal powder, etc. on the substrate. There is to do.

In order to achieve the above object, according to a first aspect of the present invention, there is provided a mounting table on which a substrate to be cleaned is mounted, hydrogen and oxygen are burned, and water vapor containing oxygen, ozone and radical oxygen is generated. A container installed at a distance from the mounting table, and having one end connected to the container and a water vapor supply nozzle facing the surface of the substrate of the mounting table at the other end, and is generated in the container A cleaning apparatus comprising: a steam supply pipe that continuously or intermittently supplies the steam and sprays the steam on the surface of the substrate by the steam supply nozzle.

According to a second aspect of the present invention, the water vapor supply pipe according to the first aspect has a spiral water vapor passage that mixes and stirs oxygen generated in the container, water vapor containing ozone and radical oxygen during supply. It is characterized by.

According to a third aspect of the present invention, the water vapor supply pipe according to the first aspect has a vapor supply pipe connected to a supply source of the organic solvent inside, the organic solvent is sprayed from the water vapor supply nozzle onto the surface of the substrate, and The condensation of water vapor is prevented, and the water film on the substrate is replaced with an organic solvent.

According to this invention, in cleaning the surface of the substrate, hydrogen and oxygen are combusted in a container, and the water vapor after combustion is jetted onto the surface of the substrate. Therefore, even if the piping from the generation of ozone to the substrate is lengthened, high-concentration ozone can be supplied to the substrate without self-decomposition, and the substrate can be installed at an arbitrary position.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows an overall configuration of an ozone water vapor cleaning apparatus, which is provided with a cylindrical container 1 made of quartz glass for burning high purity hydrogen and high purity oxygen to generate water vapor. A heater 2 is provided on the outer periphery of the container 1 so as to surround the container 1 so that the inside of the container 1 can be constantly heated to 600 ° C. or higher. A water cooling jacket 3 for absorbing radiant heat from the heater 2 and radiant heat generated from the combustion flame in the container 1 is provided on the outer periphery of the container 1 and the heater 2.

  Further, a flame detector 4 is provided in the water cooling jacket 3 for the purpose of monitoring the combustion flame in the container 1. Further, a hydrogen supply pipe 5 and an oxygen supply pipe 6 are provided in the container 1 through the water cooling jacket 3, and a hydrogen nozzle 7 and an oxygen nozzle located inside the container 1 are provided in the hydrogen supply pipe 5 and the oxygen supply pipe 6. 8 is provided.

  The hydrogen supply pipe 5 and the oxygen supply pipe 6 are connected to the hydrogen supply port 10 and the oxygen supply port 11 of the hydrogen / oxygen flow control device 9 by piping. Further, the hydrogen supply pipe 5 and the oxygen supply pipe 6 are connected to the nitrogen supply ports 12 and 13 by piping. The hydrogen / oxygen flow control device 9 is provided with a pipe 15 for connecting the hydrogen supply port 10 and the hydrogen supply source 14, and the pipe 15 is provided with a hydrogen valve 16 and a hydrogen mass flow controller 17. Furthermore, a nitrogen valve 20 is provided in a pipe 19 that connects the nitrogen supply port 12 and the nitrogen supply source 18.

  The hydrogen / oxygen flow control device 9 is provided with a pipe 22 for connecting the oxygen supply port 11 and the oxygen supply source 21, and an oxygen valve 23 and an oxygen mass flow controller 24 are provided in the pipe 22. Furthermore, a nitrogen valve 26 is provided in the pipe 25 connecting the nitrogen supply port 13 and the nitrogen supply source 18.

The container 1 is connected to the chamber 30 via a water vapor supply pipe 29. On the inlet side of the water vapor supply pipe 29, there is provided a stirring and mixing plate 31 that is a combination of a plurality of plates having a plurality of small holes, and is mixed when the water vapor H ₂ O, ozone O _{3 and} radical oxygen RO pass through. It is designed to be stirred. Further, a quartz rod 32 is welded in a spiral structure inside the water vapor supply pipe 29, and a helical water vapor passage 33 is formed inside the water vapor supply pipe 29. Then, water vapor H ₂ O, ozone O ₃ , and radical oxygen RO are injected into the chamber 30 from the outlet of the water vapor supply pipe 29 as ozone water vapor H ₂ O + O ₃ that is further mixed and stirred inside the water vapor supply pipe 29. It is comprised so that.

A substrate mounting table 36 that rotates about a rotation shaft 35 is provided inside the chamber 30, and a substrate 37 such as a semiconductor wafer is mounted on the substrate mounting table 36. A water vapor supply nozzle 38 provided at the outlet of the water vapor supply pipe 29 is provided at the center of the upper surface of the substrate 37 so as to be opposed thereto. The distance H between the substrate 37 and the water vapor supply pipe 29 is set to several millimeters, and the ozone water vapor H ₂ O + O ₃ is efficiently dispersed uniformly by preventing the ozone water vapor H ₂ O + O ₃ from scattering and increasing the internal pressure on the substrate 37. It is configured to be supplied to the surface of the substrate 37.

In addition, an IPA vapor supply pipe 39 for supplying isopropyl alcohol (hereinafter referred to as IPA) as an example of an organic solvent is provided inside the water vapor supply pipe 29. The IPA vapor supply pipe 39 has an IPA supply port 40 and a pure water supply port 41 at a base end portion, and a distal end portion faces the water vapor supply nozzle 38. Then, the IPA vapor supply pipe 39 is heated by ozone water vapor H ₂ O + O _{3 of} several hundred degrees Celsius flowing inside the water vapor supply pipe 29, and the IPA vapor is not condensed in the IPA vapor supply pipe 39, and the water vapor supply nozzle 38 is used. Can be sprayed from. Incidentally, IPA vapor V is capable of jetting the ozone water vapor _H 2 _O + O ₃ simultaneously or ozone water vapor _H 2 _O + O ₃ IPA vapor supply nozzle 38 alone supplies before (after outage) of.

  Next, the operation of the ozone water vapor generating apparatus configured as described above will be described.

  The hydrogen / oxygen flow control device 9 performs supply (stop) control of hydrogen and oxygen supplied into the container 1 and flow control of hydrogen and oxygen. The flow rate ratio between the oxygen flow rate and the hydrogen flow rate is in the range of 1: 1.2 to 1: 2.02, and preferably in the range of 1: 1.5 to 1: 1.9.

When it is necessary to generate steam, the hydrogen valve 16 and the oxygen valve 23 of the hydrogen / oxygen flow control device 9 are opened, and hydrogen H ₂ whose flow rate is controlled by the hydrogen mass flow controller 17 and the oxygen mass flow controller 24 is supplied to the hydrogen supply port 10, Oxygen O ₂ is supplied from the oxygen supply port 11 to the hydrogen supply pipe 5 and the oxygen supply pipe 6, respectively, and ejected from the hydrogen nozzle 7 and the oxygen nozzle 8 in the container 1.

At this time, since the temperature inside the container 1 is 600 ° C. which is higher than the ignition temperature of hydrogen H ₂ , the temperature inside the container 1 becomes a hydrogen ignition source, and hydrogen H ₂ and oxygen O ₂ are contained inside the container 1. A hydrogen combustion flame 27 is generated, and clean water vapor 28 is generated. The amount of water vapor 28 generated is determined by the hydrogen flow rate controlled by the oxygen mass flow controller 24, and the temperature of the water vapor 28 injected from the water vapor supply pipe 29 increases as the hydrogen flow rate during combustion increases as shown in Table 1. To do. However, the steam temperature decreases with the extension of the steam supply pipe 29.

As one of the methods of generating ozone, when an ultraviolet ray of 240 nm or less, called an ozone generation line having a short wavelength, is irradiated to oxygen molecules, the oxygen molecules are dissociated to generate two oxygen atoms. bonded to the oxygen molecules of ozone O ₃ is generated. Briefly, it is as follows.

O ₂ + UV (240 nm) = O + O
The oxygen atom combines with other oxygen,
O ₂ + O = O ₃ (ozone)
Ozone generating means is a proper vessel 1, by burning in a combustion ratio of the proper oxygen and hydrogen, the excess oxygen O ₂ which has not contributed to the combustion in the container 1 is generated, this excess oxygen O ₂ It becomes oxygen necessary for the production of ozone O ₃ . Then, ultraviolet light having a wavelength of 240 nm or less necessary for generating ozone O ₃ is irradiated from the hydrogen combustion flame 27.

Specifically, the combustion reaction formula in which hydrogen H ₂ and oxygen O ₂ are combusted to generate steam is as follows:
2H ₂ + O ₂ = 2H ₂ O
Two volumes of steam are generated from two volumes of hydrogen and one volume of oxygen. That is, in the case of complete combustion with 2 volumes of hydrogen and 1 volume of oxygen, only water vapor is generated without hydrogen and oxygen remaining. Volume ratio during complete combustion; hydrogen / oxygen = 2
Therefore, the ozone generation means sets the flow rates of hydrogen H ₂ and oxygen O ₂ with the oxygen mass flow control 24 and the hydrogen mass flow controller 17 so that the volume ratio of hydrogen and oxygen during combustion is about 1.9, and combustion Oxygen O ₂ is sometimes generated to generate ozone. This excess oxygen O ₂ absorbs ultraviolet light of 240 nm or less emitted from the hydrogen combustion flame 27 and dissociates into two oxygen atoms, and the oxygen atoms are combined with other excess oxygen O _2, and ozone O ₃ Is generated.

Ozone O ₃ is instantaneously decomposed by absorbing ultraviolet rays of 254 nm or heat of about 400 ° C. or more, and generates excited oxygen atoms (radical oxygen RO). This radical oxygen RO oxidizes the organic substance, decomposes it into carbon dioxide (CO ₂ ) and water (H ₂ O), and volatilizes and removes it.

  As described above, the organic matter is a chemical reaction that is oxidized by radical oxygen RO to carbon dioxide and water, and is volatilized and removed. Therefore, the removal rate of the organic matter strongly depends on the high temperature, and high-temperature ozone is effective.

In general, when ozone O ₃ is used for substrate cleaning, the substrate 37 is heated to promote a chemical reaction. Further, in the case of ozone O _{3 +} UV when compared to ozone O _{3 +} UV + steam 28, in this process, ozone O ₃ is dissolved in water, OH groups are generated, which largely involved in removing organic substances To do.

The means for generating radical oxygen RO is to burn 254 nm ultraviolet light simultaneously with radiation of 240 nm or less from the hydrogen combustion flame 27 by burning in a proper container 1 with a proper combustion ratio of oxygen O ₂ / hydrogen H _2. Has also been radiated. Further, the heat radiation temperature of the hydrogen combustion flame 27 is several hundred degrees Celsius or more. Therefore, the ozone O ₃ generated during combustion absorbs 254 nm ultraviolet rays emitted from the hydrogen combustion flame 27 or absorbs heat of several hundred degrees Celsius or more emitted from the hydrogen combustion flame 27 to generate radical oxygen. Generate RO.

Since the radical oxygen RO is a high temperature of 400 ° C. or higher, it is not necessary to heat the substrate 37 to promote a chemical reaction. Also, ozone O ₃ is to be generated simultaneously with the generation of steam H _{2 O,} there is no need to supply water vapor H _{2 O} from another line.

Water vapor H ₂ O, ozone O _{3, and} radical oxygen 30 are mixed and stirred when passing through the stirring and mixing plate 32, and further become ozone water vapor H ₂ O + O ₃ mixed and stirred inside the water vapor supply pipe 29. Injected from 29 outlets. The ozone concentration of ozone water vapor H ₂ O + O ₃ injected from the outlet of the water vapor supply pipe 29 is determined by the hydrogen flow rate controlled by the oxygen mass flow controller 24, and increases as the hydrogen flow rate during combustion increases as shown in Table 2. To do.

  As shown in Table 2, the ozone concentration injected from the outlet of the water vapor supply pipe 29 when burned at a hydrogen flow rate of 50 L / min is about 100 to 120 ppm, but actually ozone of several hundred ppm is generated. Yes. This decrease in ozone concentration contributes to the generation of radical oxygen RO.

  The means for supplying heated nitrogen gas is supplied from the oxygen nozzle 8 into the container 1 by supplying nitrogen from the nitrogen supply port 13 to the oxygen supply pipe 6. Since the temperature inside the container 1 is 600 ° C. or higher, heated nitrogen gas is generated at the temperature inside the container 1 and can be injected from the nitrogen supply nozzle 38 of the water vapor supply pipe 29 onto the surface of the substrate 37.

  The temperature of the heated gas injected from the nitrogen supply nozzle 38 increases as the heated nitrogen gas flow rate increases as shown in Table 3. However, the heating nitrogen gas temperature decreases with the extension of the water vapor supply pipe 29.

  FIG. 2 is a flowchart for explaining an embodiment of a single wafer cleaning apparatus for removing fine particles, organic substances, and metals on the substrate 37 using the ozone water vapor generating apparatus of FIG.

  Specifically, a substrate cleaning method using a single wafer spin cleaning method using an ozone water vapor generating apparatus will be described in detail with reference to the flowchart of FIG. 2 and FIGS. As shown in FIG. 3, the substrate 37 is set on the substrate mounting table 36 (step S1). Next, the ozone water vapor generating device is rotated in the direction of the arrow to lower the chamber 30 of the water vapor supply pipe 29 to the position just above the substrate 37 in the direction of the arrow, and to a predetermined position where the chamber 30 completely covers the substrate 37. (Step S2).

  As shown in FIG. 4, after the water vapor supply pipe 29 is installed at a predetermined position, the substrate 37 on the substrate mounting table 36 is rotated in a horizontal state around the rotation shaft 35, and the IPA vapor supply pipe 39 to the substrate 37 is rotated. Pure water is injected into the water (step S3). Then, a water film is formed on the substrate 37 (step S4).

Next, as shown in FIG. 5, hydrogen H ₂ and oxygen O ₂ are supplied into the container 1 to start combustion in the container 1 (step S5). Simultaneously with the generation of the water vapor 28 in the container 1, ozone O ₃ and radical oxygen RO are generated, and mixed with stirring when passing through the stirring and mixing plate 31 and the water vapor supply pipe 29 to generate ozone vapor H ₂ O + O _3. To do. This ozone vapor H ₂ O + O ₃ is sprayed onto the substrate 37 from the water vapor supply nozzle 38 of the water vapor supply pipe 29 (step S6).

Ozone water is formed on the substrate 37 while dissolving ozone water vapor H ₂ O + O ₃ at a high concentration in the water film of the substrate 37 (step S7). Metal atoms such as Fe, Al, and Cu on the substrate 38 are ionized by the ozone water, and dissolved and removed in the ozone water. Also, the organic matter on the substrate 37 is decomposed by the high oxidizing power of ozone water and dissolved and removed in the ozone water (step S8).

In addition, when the substrate cleaning with only the ozone water vapor H ₂ O + O ₃ is required, the step of forming a water film by injecting pure water onto the substrate 37 is omitted, and only the ozone water vapor H ₂ O + O ₃ is formed on the substrate 37. , For example, the organic matter on the substrate 37 is oxidized by radical oxygen, and volatilized and removed as carbon dioxide and water.

As described above, since ozone O ₃ is generated simultaneously with the generation of the water vapor 28, ozone is dissolved in the water film condensed on the substrate 37, and OH groups are generated, which is greatly involved in organic matter removal. Further, since the ozone O ₃ and radical oxygen are as high as 400 ° C. or higher, it is not necessary to heat the substrate 37 in advance in order to promote the oxidation reaction. It is also possible to rotate the water vapor supply pipe 27 from the central portion on the substrate 37 toward the end of the substrate 37 while ozone water vapor H ₂ O + O ₃ and pure water are jetted onto the substrate 37.

Next, ozone water vapor H ₂ O + O ₃ and pure water are sprayed onto the substrate 37 for a predetermined time (step S9). Thereafter, the supply of hydrogen H ₂ and oxygen O ₂ and pure water 40 supplied into the container 1 are stopped (step S10).

  Next, as shown in FIG. 6, IPA vapor is supplied from the IPA vapor generator to the IPA vapor supply pipe 39, and the IPA vapor is injected from the IPA vapor supply nozzle 38 onto the substrate 37 (step S <b> 11). IPA is condensed thereon (step S12), and the water film on the substrate 37 is replaced with IPA (step S13). It is also possible to rotate the water vapor supply pipe 29 from the central portion on the substrate 37 toward the end portion of the substrate 37 while the IPA vapor is jetted onto the substrate 37.

Next, as shown in FIG. 7, after the IPA vapor is sprayed onto the substrate 37 for a predetermined time, the water film on the substrate 37 is replaced with IPA, and then the IPA vapor supplied to the IPA vapor supply pipe 29 is replaced. Supply is stopped (step S14). Nitrogen N ₂ is supplied from the oxygen supply pipe 6 connected to the nitrogen supply port 11 toward the wall surface in the container 1. Since the temperature in the container 1 is 600 ° C. or higher, the temperature in the container 1 is generated, and heated nitrogen of 100 ° C. or higher is sprayed from the nitrogen supply nozzle 38 onto the substrate 37 through the water vapor supply pipe 29 (step S15).

  Therefore, the IPA on the substrate 37 is diverged and the surface of the substrate 37 is dried (step S16). It is also possible to rotate the water vapor supply pipe 29 from the central portion on the substrate 37 toward the end portion of the substrate 37 while jetting heated nitrogen onto the substrate 37.

  As shown in FIG. 8, after the surface of the substrate 37 is dried, the supply of nitrogen is stopped (step S <b> 17), the ozone water vapor generating device is raised to a predetermined position and rotated, and the water vapor supply pipe 29 is moved from above the substrate 37. Move upward. After the movement is completed, the substrate 37 is unloaded from the single wafer spin cleaning machine.

As described above, hydrogen H ₂ and oxygen O ₂ are combusted, and the water vapor 28 after combustion is generated continuously or intermittently, whereby fine particles, organic matter, metal powder, etc. on the substrate 37 are efficiently removed. be able to. Furthermore, even if the piping from the generation of ozone to the substrate 37 is lengthened, high-concentration ozone can be supplied to the substrate without self-decomposition, and the substrate can be installed at an arbitrary position.

  The present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Moreover, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, the constituent elements over different embodiments may be combined.

BRIEF DESCRIPTION OF THE DRAWINGS The 1st Embodiment of this invention is shown, The schematic block diagram of an ozone water vapor generating apparatus. The flowchart which shows the effect | action of the ozone water vapor generating apparatus of the embodiment. Action | operation explanatory drawing of the ozone water vapor generating apparatus of the embodiment. Action | operation explanatory drawing of the ozone water vapor generating apparatus of the embodiment. Action | operation explanatory drawing of the ozone water vapor generating apparatus of the embodiment. Action | operation explanatory drawing of the ozone water vapor generating apparatus of the embodiment. Action | operation explanatory drawing of the ozone water vapor generating apparatus of the embodiment. Action | operation explanatory drawing of the ozone water vapor generating apparatus of the embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Container, 5 ... Hydrogen supply pipe, 6 ... Oxygen supply pipe, 29 ... Water vapor supply pipe, 37 ... Substrate

Claims (3)

A mounting table for mounting a substrate to be cleaned;
  Burning hydrogen and oxygen to produce water vapor containing oxygen, ozone and radical oxygen, and a container installed away from the mounting table,
  One end is connected to the container, and the other end has a water vapor supply nozzle facing the surface of the substrate of the mounting table, and continuously or intermittently supplies water vapor generated in the container. A water vapor supply pipe for spraying and cleaning the surface of the substrate by a supply nozzle;
  A cleaning apparatus comprising: 2. The water vapor supply pipe according to claim 1, wherein the water vapor supply pipe has a spiral water vapor passage that mixes and stirs the water containing oxygen, ozone, and radical oxygen generated in the container during supply. Cleaning device. The water vapor supply pipe has a vapor supply pipe connected to a supply source of the organic solvent inside, and sprays the organic solvent from the water vapor supply nozzle onto the surface of the substrate to prevent the water vapor from condensing on the substrate. The cleaning apparatus according to claim 1, wherein the water film is replaced with an organic solvent.

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