JP4097372B2 - High concentration ozone-containing gas storage method, high concentration ozone-containing gas storage device, oxidation treatment method and oxidation treatment device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a high-concentration ozone-containing gas storage method for storing a high-concentration ozone-containing gas, a high-concentration ozone-containing gas storage device, and an oxidation treatment method for efficiently performing various oxidation treatments using the stored high-concentration ozone gas. And an oxidation treatment apparatus.
[0002]
[Prior art]
Recently, ozone (element symbol: O _Three ) Oxidation using strong oxidizing power is progressing in various fields including water and sewage treatment. In particular, in the field of semiconductor device manufacturing, Si wafer cleaning and TEOS-CVD (Tetra Ethyl Ortho Silicate-Chemical Vapor Deposition) is being studied.
[0003]
Si wafer cleaning uses ozone water in which ozone gas is dissolved in pure water as a cleaning liquid, and it has been announced that heavy metals and organic substances on Si wafer can be removed by using together with dilute hydrofluoric acid aqueous solution.
[0004]
In addition, TEOS-CVD is used to form an interlayer insulating film when a semiconductor element is formed into a multilayer wiring, and it is characterized in that the unevenness of the wafer surface due to the electrode can be flattened by the insulating film, and ozone is applied to this TEOS-CVD. It has been reported that the addition improves the planarization performance.
[0005]
These announcements and reports are examples of using a relatively low concentration ozone gas of about 10%, but using a relatively high concentration ozone gas of 80% or more is considered in the conventional use of low concentration ozone gas. The possibility of a new application that has not been started is pointed out, and as an example, Japanese Patent Laid-Open No. 8-335576 discloses the formation of a silicon oxide film such as a semiconductor device. According to this publication, it is possible to form an oxide film at a relatively low temperature such as room temperature, which cannot be achieved by a conventional thermal oxidation method, by using a relatively high concentration ozone gas. It has been introduced that it is possible to form a high-quality oxide film with few defect structures.
[0006]
A conventional silicon oxide film forming method will be described based on the apparatus shown in FIG. In the figure, 20 is a vacuum chamber, 21 is a high-purity ozone generator, and 22 is a transport pipe for supplying high-purity ozone to the vacuum chamber 20.
[0007]
First, as a first step, the surface of the sample 27 to be oxidized is chemically subjected to hydrogen termination, for example, by the Shiraki method. Instead of the Shiraki method, after a 7 × 7 clean surface of the sample surface is exposed, the sample temperature is kept at 380 ° C. in the vacuum chamber 20 to expose the sample 27 to hydrogen gas (the hydrogen gas supply system is not shown). Hydrogen termination treatment can also be achieved by heating a tungsten filament (not shown) provided at a position facing the sample 27 at a high temperature to dissociate hydrogen molecules into atoms. However, if it is not desirable to heat the sample 27 even at a temperature of about 380 ° C. although it is sufficiently lower than the high temperature environment in the conventional thermal oxidation method that reaches 900 ° C., the former Shiraki It is preferable to use chemical methods such as law. The surface of the sample 27 thus hydrogen-terminated is extremely smooth and flat on the atomic layer order.
[0008]
Then, as a second step, as shown in FIG. 15, high-purity ozone generated by the ozone generator 21 is introduced into the vacuum chamber 20 as a beam-like ozone jet 23 through the transport pipe 22, By performing the oxidation treatment by spraying on the oxidized sample 27, it is possible to form a high-quality oxide film with less suboxide layer and defect structure.
[0009]
Here, as the high-purity ozone generator 21, a method of storing and generating almost 100% pure ozone by utilizing the difference in vapor pressure at low temperatures between ozone and oxygen is known. As an example, The apparatus introduced in Japanese Patent Publication No. 5-17164 which generates almost 100% high concentration ozone gas by liquefying and storing the generated ozone gas and then evaporating it can be used.
[0010]
By using such a high purity ozone generator, a high ozone concentration of 80% or more can be obtained when introduced into the vacuum chamber 20, and the irradiation time of the ozone jet 23 is also in units of 1 mS. Besides being controllable, the pressure fluctuation of the ozone jet 23 can be suppressed to within 10%.
[0011]
Reference numeral 25 is an XPS (X-ray photoemission spectroscopy) analyzer for analyzing the sample surface, 24 is an X-ray source, and 26 is an X-ray, which are provided as peripheral devices of this seed oxidation treatment apparatus. Is.
[0012]
[Problems to be solved by the invention]
By the way, even if high concentration ozone gas of almost 100% can be generated by the ozone generator, about 20% is decomposed into oxygen while passing through the transport pipe. However, the decomposition here can reduce the ozone decomposition rate to some extent by making the transport pipe as thick and short as possible.
[0013]
However, since the ozone gas blown into the vacuum chamber spreads by diffusion, some components that actually collide and react on the sample to be oxidized. In order to increase the efficiency, there is no other way but to make the distance from the end of the piping port to the sample to be oxidized as close as possible.
[0014]
In addition, in an apparatus using a method of spraying an ozone jet onto a sample to be oxidized, the degree of vacuum cannot be worse than a certain value due to the influence on the surface analyzer installed in the vacuum chamber. The amount of ozone supply (supply rate) is inevitably limited because it is not desired to apply a load with strong ozone gas, and the sample to be oxidized can oxidize several atomic layers (several nm) at room temperature even with ozone having strong oxidizing power. It takes time or more, and it is necessary to heat the sample to be oxidized to several hundred degrees in order to cause oxidation at high speed.
[0015]
As described above, the conventional spraying method can supply only ozone gas decomposed at a certain rate, and the supply amount and supply speed are limited, and the effective utilization rate of the gas is low. Even if it is used, it is difficult to form an oxide film superior to a conventional thermal oxide film using oxygen gas.
[0016]
Therefore, the present invention solves these problems, prevents a decrease in ozone gas concentration, and can effectively utilize its strong oxidizing power, a high-concentration ozone-containing gas storage device, a high-concentration ozone-containing gas storage device, and an oxidation A treatment method and an oxidation treatment apparatus are provided.
[0017]
[Means for Solving the Problems]
The first invention is a method of cooling a target substrate made of a material that is inert to ozone and has a good thermal conductivity and disposed in a vacuum chamber, and supplying high-purity ozone gas onto the target substrate. Adsorption of ozone gas on the target substrate as solid ozone, and supply to the target substrate by stopping the supply of high-purity ozone gas and raising the target substrate temperature until the ozone vapor pressure is the same as the pressure in the vacuum chamber The present invention relates to a method for storing a high-concentration ozone-containing gas, comprising a step of removing a gas other than ozone.
[0018]
The second invention is characterized in that in the step of removing a gas other than the ozone gas of the first invention, the temperature of the target substrate is raised to 40-60K.
[0019]
The third invention is characterized in that the target substrate of the first or second invention has translucency. As a substrate that can be used here, sapphire, fused quartz, calcium fluoride, magnesium fluoride, lithium fluoride, calcite, and the like can be used. Potassium chloride, sodium chloride, potassium bromide, crystal, diamond, fluorine The possibility of using sodium fluoride, barium fluoride, beryllium, etc. is also considered.
[0020]
The fourth invention is the first to third inventions. Any one of the inventions As the target substrate, a sapphire substrate considered to be optimal is used.
[0021]
According to a fifth aspect of the present invention, there is provided a target substrate made of a material that is inert to ozone and has good thermal conductivity, disposed in a vacuum chamber, a cooling means for cooling the target substrate, and high-purity ozone gas on the target substrate. It has a transporting tube to be supplied and a heating means for raising the temperature of the target substrate.
[0022]
The sixth invention is characterized in that the target substrate of the fifth invention has translucency. As a substrate that can be used here, sapphire, fused quartz, calcium fluoride, magnesium fluoride, lithium fluoride, calcite, and the like can be used. Potassium chloride, sodium chloride, potassium bromide, crystal, diamond, fluorine The possibility of using sodium fluoride, barium fluoride, beryllium, etc. is also considered. The seventh invention is characterized in that in the storage device for high-concentration ozone-containing gas of the fifth and sixth inventions, a sapphire substrate considered to be optimal is used.
[0023]
The eighth invention is the first to fourth inventions. Any one of the inventions The solid ozone surface stored by the high-concentration ozone-containing gas storage method is irradiated with a laser beam and ablated to irradiate an ozone beam toward the surface of the sample to be oxidized in a vacuum chamber facing the target substrate. The present invention relates to an oxidation treatment method comprising steps.
[0024]
The ninth invention is characterized in that the laser light in the eighth invention has a wavelength of 200 to 370 nm in the vicinity of ultraviolet light where ozone absorption strongly occurs. Further, it is considered that 220 to 300 nm (Hartley band) having the strongest absorption spectrum of ozone is more preferable.
[0025]
The tenth invention is characterized in that the oxidation region of the sample to be oxidized is adjusted by adjusting the aperture, irradiation position, or distance between the target substrate and the sample to be oxidized in the seventh and eighth inventions. .
[0026]
The eleventh invention is the first to fourth inventions. Any one of the inventions The solid ozone stored by the storage method of the high-concentration ozone-containing gas described in (2) is vaporized by raising the temperature of the target substrate to a temperature at which the ozone vapor pressure becomes higher than the vacuum chamber pressure, so that the target is stored in the vacuum chamber as ozone gas. The present invention relates to an oxidation treatment method comprising a step of directing toward a surface of a sample to be oxidized disposed opposite to a substrate.
[0027]
The twelfth invention is the fifth to seventh inventions. Any one of the inventions A high-concentration ozone-containing gas storage device has a configuration in which a sample to be oxidized is placed facing a target substrate in a vacuum chamber of the gas storage device, and a laser beam irradiation device for irradiating the target substrate surface with laser light is provided. The present invention relates to an oxidation processing apparatus.
[0028]
A thirteenth invention is the oxidation treatment apparatus according to the twelfth invention, wherein the laser beam irradiation device is disposed outside the vacuum chamber, a window that transmits the laser beam and maintains the vacuum state in the vacuum chamber is formed in the vacuum chamber, The present invention is characterized in that the target substrate is irradiated with laser light from a laser light irradiation device through this window.
[0029]
The fourteenth invention is the oxidation treatment apparatus according to the twelfth invention, wherein the laser beam irradiation device is disposed outside the vacuum chamber, and an optical fiber is provided that penetrates the vacuum chamber while maintaining the vacuum state in the vacuum chamber. It is characterized by irradiating the target substrate with the laser beam from the optical fiber via an optical fiber.
[0030]
15th invention is 5th-7th invention Any one of the inventions The present invention relates to an oxidation processing apparatus characterized in that a sample to be oxidized is arranged opposite to a target substrate in a vacuum chamber of a storage device for high-concentration ozone-containing gas.
[0031]
A sixteenth aspect of the present invention is the oxidation processing apparatus of the fifteenth aspect of the present invention, wherein the target substrate is the bottom surface and is made of a material which is inert to ozone and has a good thermal conductivity, and has an opening corresponding to the sample to be oxidized above A chamber is formed, and the diffusion prevention chamber and the transport pipe are communicated with each other.
[0032]
The seventeenth invention is characterized in that aluminum is used as a material that is inert to ozone and has good thermal conductivity in the oxidation treatment apparatus of the sixteenth invention.
[0033]
The eighteenth aspect of the present invention is claims 12 to 17. Any one of the inventions The oxidation processing apparatus described in (1) is characterized by having moving means for moving the sample to be oxidized in the vacuum chamber.
[0034]
The nineteenth invention is characterized in that a manipulator is used as the moving means in the eighteenth invention.
[0035]
DETAILED DESCRIPTION OF THE INVENTION
Applicants believe that if a highly directional ozone beam with controlled composition and momentum can be supplied to the surface of the sample to be oxidized, the advantages of ozone can be further extracted, and particle emission with high translational energy can be obtained. We focused on the laser ablation process that has been confirmed.
[0036]
First, ozone was solidified once, and the composition and momentum of the beam generated when the ablation conditions were changed were analyzed, and an oxidation experiment of metallic copper was attempted.
[0037]
FIG. 1 shows an outline of the experimental apparatus. In FIG. 1, 1 is a vacuum chamber, and 2 is a transport pipe for supplying high-purity ozone generated by an ozone generator (not shown). Reference numeral 3 denotes an excimer laser used as a laser beam irradiation apparatus for irradiating a laser beam, and a KrF excimer laser is used as a laser light source. Reference numeral 4 denotes a target substrate, and in this embodiment, sapphire that has little interaction with ozone and does not absorb laser light is used. The target substrate 4 is preferably made of a material that has good thermal conductivity and does not react with ozone gas, and the target substrate 4 is most preferably sapphire, but fused quartz, calcium fluoride, magnesium fluoride, lithium fluoride, calcite, or the like is used. It is possible to use potassium chloride, sodium chloride, potassium bromide, crystal, diamond, sodium fluoride, barium fluoride, beryllium, and the like. It is also conceivable to use glass, aluminum or the like that has little reaction with ozone. However, considering the influence of laser light irradiation in the absence of solid ozone, the target substrate is preferably a light-transmitting material that transmits laser light.
[0038]
Reference numeral 5 denotes a copper block thermally coupled to the target substrate 4, and the target substrate 4 is connected to a cold head 7 having a heater 6 as a heating means 6 and a refrigerator as a cooling means through the copper block 5, respectively. These control the temperature of the target substrate 4. 8 is a thermometer for measuring the temperature of the target substrate 4, and 9 is a quadrupole analyzer tube (QMS) provided facing the target substrate 4 in order to measure the composition and speed distribution of the emitted particles. It is. Reference numeral 10 denotes a preamplifier for amplifying the output (collector current) of the QMS 9, and reference numeral 11 denotes a digital oscilloscope.
[0039]
The vacuum chamber 1 is formed with a window 1a that transmits laser light and maintains the vacuum state in the vacuum chamber 1. The laser light from the excimer laser 3 is passed through the window onto the target substrate 4. It is configured to be irradiated.
[0040]
Using the experimental apparatus configured as described above, an appropriate amount of ozone gas is supplied from the high-purity ozone generator onto the sapphire substrate 4 cooled to about 50K in the vacuum chamber-1, and then the sapphire substrate 4 temperature is set. While maintaining an arbitrary temperature, the excimer laser 3 irradiates laser light from the direction of 45 degrees on the surface of the sapphire substrate 4, and the composition and speed distribution of particles emitted for each laser pulse are set at positions facing the sapphire substrate 4. Measurement was performed with the provided quadrupole analyzer tube (QMS) 9. The output (collector current) of the QMS 9 was amplified by the preamplifier 10 and recorded by the digital oscilloscope 11 as a function of time from laser pulse application. To improve the S / N ratio, 100 pulses were integrated. Specific experiments will be described below.
[0041]
First, it tried to adsorb | suck solid ozone on the sapphire substrate 4, and investigated the adsorption amount (growth speed) and the purity of solid ozone. When the temperature of the sapphire substrate 4 is cooled to 33 K and high-purity ozone gas is supplied, concentric interference fringes appear on the sapphire substrate 4 and the number of fringes increases and spreads outward with time. It was.
[0042]
Here, as a high-purity ozone generator for supplying high-purity ozone, the device introduced in the aforementioned Japanese Patent Publication No. 5-17164 was used, but in addition, ozone molecules were once adsorbed using a molecular sieve or the like. An apparatus using a method of obtaining high-purity ozone by storing and then desorbing and vaporizing can also be used.
[0043]
Next, when the supply of the high-purity ozone gas was stopped and then the temperature of the sapphire substrate 4 was slowly raised, the pressure change shown in FIG. 2 was confirmed.
[0044]
In FIG. 2, due to the signal intensity ratio of QMS9 (m / e =) 32 and 48 and the vapor pressure, the pressure rise near 40K is due to oxygen (due to ozonolysis in the transport tube 2), and 60 It was confirmed that the pressure increase at ˜80 K was due to the vaporization of ozone. Further, from the signal intensity ratio of the latter QMS 9, it was confirmed that ozone having a purity of 60% or more was adsorbed on the sapphire substrate 4 as solid ozone.
[0045]
After confirming that a sufficient amount of solid ozone was adsorbed, ablation was performed with the excimer laser 3 to examine the composition of the emitted particles, the velocity distribution, and the like. At that time, experiments were also performed by changing the laser power density and the sapphire substrate 4 temperature.
[0046]
FIG. 3 shows typical velocity distributions of ozone and oxygen (relationship between signal intensity and time from laser application). As can be seen from FIG. 3, ozone is ejected at a substantially constant speed, but oxygen varies from a fairly fast component to a slow component. This is the one that was decomposed into oxygen when adsorbed on the sapphire substrate 4, the one decomposed into oxygen at the time of ablation, the one decomposed on the way to the QMS 9 in the beam state, and detected after colliding with the wall of the vacuum chamber 1 many times. This is thought to be because there are things.
[0047]
FIG. 4 shows changes in the ozone velocity distribution when the laser power density is changed. In any case, it has a peak at around 300 ms, and this velocity distribution is almost the same as the experimental result when it is considered that the emitted particles are in translation at high temperature of 900 K and in thermal equilibrium (Boltzmann approximation). Note that when the laser power density is decreased, the total ozone emission amount is reduced, but it can be seen that there are still components having a high speed.
[0048]
FIG. 5 shows changes in the signal intensity integration ratio of ozone and oxygen when ablation by laser light irradiation is performed while changing the temperature of the sapphire substrate 4. This ratio decreases as the temperature of the sapphire substrate 4 decreases. This is considered to be because the ozone decomposition rate at the time of ablation is increased in addition to the decrease in the purity of solid ozone on the sapphire substrate 4 as the temperature decreases.
[0049]
From the above experimental results, the applicant first adsorbs solid ozone onto the sapphire substrate used in the experiment, and after the solid ozone adsorption, the target substrate temperature is set to a temperature at which the ozone vapor pressure becomes the same as the pressure in the vacuum chamber ( In the experiment, it is possible to improve the ozone concentration by removing gas other than ozone adsorbed on the target substrate by raising the temperature to 40-60K (optimal value). It was confirmed that a gas storage method and storage device were obtained.
[0050]
Furthermore, it is possible to supply high-temperature, high-purity ozone gas with a low decomposition rate to the sample to be oxidized, to make the most effective use of ozone gas without waste, and to precisely control the amount and rate of ozone gas supply, from ablation experiments using laser light irradiation. Furthermore, it was considered that by supplying ozone gas under optimum conditions, the high oxidizing power of ozone gas can be effectively extracted and used as an oxidation treatment apparatus. The oxidation processing apparatus according to this embodiment will be described below.
(First embodiment)
A first embodiment of the oxidation processing apparatus according to the present invention will be described with reference to FIG. The first embodiment relates to an oxidation processing apparatus that uses laser light irradiation to vaporize solid ozone adsorbed on a target substrate.
[0051]
In the figure, 1 is a vacuum chamber, and 2 is a transport pipe for supplying high-purity ozone gas from the high-purity ozone generator into the vacuum chamber 1. 3 is an excimer laser that irradiates laser light, 4 is a target substrate (also using a sapphire substrate in this embodiment), 5 is a copper block, 6 is a heater used as heating means, and 7 is a refrigerator used as cooling means. is there. The vacuum chamber 1 is formed with a window 1a that transmits laser light and maintains the vacuum state in the vacuum chamber 1, and the target substrate 4 is irradiated with the laser light from the excimer laser 3 through this window. It is configured to be. As the refrigerator 7, a refrigerator having a cold head may be used as in the above-described experiment. 12 is an ozone gas outlet, 13 is a high-purity ozone generator, and 14 is an oxidized sample to be oxidized. Further, illustrations and descriptions of peripheral devices such as an XPS for analyzing the surface of the sample to be oxidized, an X-ray source, and a vacuum pump for evacuating the vacuum chamber are omitted.
[0052]
With the above configuration, first, the sapphire substrate 4 disposed near the ozone gas outlet 12 in the vacuum chamber 1 can be set to a melting point of ozone of 80 K or less by the refrigerator 7 through the copper block 5 as in the above-described experiment. Lower as much as possible. As the temperature, a temperature at which the vapor pressure of oxygen is sufficiently lower than the pressure in the vacuum chamber 1 is good, and in this embodiment, it was 33K.
[0053]
Then, high-purity ozone gas from the high-purity ozone generator 13 is blown toward the sapphire substrate 4 from the blowout port 12. At this time, since the blowout port 12 is provided near the target substrate 4, most of the ozone gas emitted from the blowout port 12 can be solidified and trapped on the sapphire substrate 4. Almost no rise is caused, and a necessary and sufficient amount of ozone-containing gas (including oxygen) can be adsorbed onto the sapphire substrate 4. While the ozone is adsorbed on the sapphire substrate 4, the sample to be oxidized 14 is preferably kept away from the facing position of the sapphire substrate 4 as indicated by a dotted line in FIG. 6. The adsorption amount can be adjusted by changing the time for adsorbing the ozone-containing gas and the size of the target substrate.
[0054]
After the necessary amount of adsorption is completed, the valve is closed to stop the supply of ozone gas, and the temperature of the sapphire substrate 4 is increased by the heater 6 so that the ozone vapor pressure becomes as high as the pressure in the vacuum chamber 1 (40-60K). The temperature was raised slowly until. Thereby, gases other than ozone adsorbed on the sapphire substrate 4 (gas having a melting point lower than ozone, particularly oxygen) can be removed, and the purity of solid ozone on the sapphire substrate 4 can be increased.
[0055]
Next, the sapphire substrate 4 of While keeping the temperature constant, the excimer laser 3 irradiates the solid ozone on the sapphire substrate 4 with a constant frequency (or continuous oscillation) through a window 1 a formed in the vacuum chamber 1. The laser beam to be irradiated preferably has a wavelength in the vicinity of ultraviolet light with the largest ozone absorption, specifically 200 to 370 nm, and the strongest absorption spectrum of ozone is 220 to 300 nm (Hartley band). Further preferred.
[0056]
By the way, a method of growing particles and ions that jump out when a target is irradiated with a laser beam on a substrate facing the target is known as a laser ablation method, and is often used for forming a metal thin film. This method is known to be able to form a thin film having the same composition ratio as the chemical composition existing on the target. In the case of ozone, when light is absorbed, the decomposition reaction into oxygen shown in the formula (1) occurs with some probability (several percent).
[0057]
[Expression 1]
O _Three + hn → O ₂ + O ( ¹ D) ... (1)
O ( ¹ D) is the atomic oxygen in the excited state
Therefore, in order to supply high-purity ozone gas during the oxidation treatment, the relationship between “ozone emission amount—laser energy density”, “beam energy—laser energy density”, etc. is examined in advance as shown in FIG. The energy density of light must be measured where ozone decomposition does not occur. Applicant's target substrate temperature 30K, irradiation area 9mm ² In the experiment under the conditions of the laser energy density of 27 mJ / cm ² Was confirmed to be the optimum value.
[0058]
In addition, the temperature of the target substrate during laser ablation also greatly affects the probability of ozone decomposition. In the experiments conducted by the applicants and the like, as shown in FIG. It has been confirmed that an ozone beam with a small amount can be extracted.
[0059]
Then, by irradiating the sample to be oxidized 13 with an ozone beam by irradiating the laser beam to vaporize solid ozone, the oxidation rate of the sample to be oxidized 13 is oxidized. It was confirmed that it was improved compared to the conventional case. This is because the particle group popping out by the laser ablation method has a higher translational energy due to the energy density of the laser to be irradiated, so that when this particle collides with the surface of the sample 13 to be oxidized, It is considered that the oxidation rate at the initial stage of oxidation was improved by increasing the surface temperature of the oxidized sample 13. Then, when silicon was oxidized as the sample to be oxidized 13, in the conventional ozone gas spraying method having energy of about room temperature, if the sample temperature to be oxidized is not raised to several hundred degrees Celsius, oxidation in a realistic time is not possible. Although it was not possible, it was confirmed that in this laser ablation method, the ozone gas beam collides with a translational energy of about 1000 K, so that the initial oxidation proceeds sufficiently fast even at the sample temperature to be oxidized.
[0060]
Next, since the particle group popping out by the laser ablation method has high directivity, an attempt was made to oxidize only a part of the surface of the sample to be oxidized by changing the laser irradiation position. As shown in FIG. 8, the sample 13 to be oxidized is brought as close to the target substrate 4 as possible, and when ablation is performed at an arbitrary place on the target substrate 4 for a predetermined time, a fine oxide film pattern having the same degree as the minimum beam spread of the laser is formed. I was able to.
[0061]
Further, as shown in FIG. 9, the position of the sample to be oxidized 13 is moved away from the target substrate 4 as much as possible, and the ablation is caused over a wide range of the target substrate 4 by weakening the aperture of the laser. It was possible to oxidize uniformly.
[0062]
Furthermore, the excimer laser 3 can be scanned on the target substrate on which solid ozone is adsorbed by supporting the excimer laser 3 with any means such as a galvano mirror or the like so as to be movable. With this configuration, the entire surface of the sample to be oxidized in a wider range could be oxidized.
[0063]
Here, when the relationship between the area to be ablated by irradiating the laser beam, the amount of released ozone, and the ozone beam density was measured, the result shown in FIG. 10 was obtained.
[0064]
As experimental conditions, the target substrate temperature is 30K, and the laser energy density is 27 mJ / cm. ² It was. From the results shown in FIG. 10, it was confirmed that when the laser irradiation area was larger than 4 mm 2, the amount of released ozone increased almost in proportion to the irradiation area, and that the beam purity gradually decreased as the laser irradiation area increased. This decrease in beam purity is thought to be due to the fact that solid ozone vaporizes due to a slight increase in temperature around the pole irradiated with the laser, and this effect has resulted in a decrease in beam purity. This phenomenon is caused by the emission ozone per unit area. Since the amount may be a cause of the phenomenon, it is considered that the above phenomenon due to the laser irradiation area needs to be taken into consideration when actually performing the oxidation treatment.
[0065]
Furthermore, when the energy density of the laser beam was fixed at a constant level, it was confirmed that the amount of ablation (amount of solid ozone stripped) per one time (unit time for continuous oscillation) was constant. The amount of ozone gas supplied to the sample to be oxidized can be uniquely determined depending on whether the ablation reaction has occurred once (or time). By utilizing this, a change in the oxidation rate can be controlled quantitatively, and an arbitrary oxide film forming condition can be derived.
[0066]
As described above, according to the oxidation processing apparatus of the present embodiment, laser irradiation is used for vaporization of solid ozone adsorbed on the target substrate, and at that time, the laser energy density, the temperature of the target substrate 13 and the like are set to appropriate values. Thus, a highly directional ozone beam with high kinetic energy with minimal ozone decomposition can be supplied to the sample to be oxidized. This high kinetic energy further draws out the ozone activity, allowing the initial oxidation to proceed at a high speed even when the temperature of the sample to be oxidized is as low as room temperature, and using the high directivity. Thus, oxidation of a large-diameter sample and fine processing of the surface are possible.
[0067]
In the present embodiment, the laser beam is transmitted through the vacuum chamber 1 and a window for maintaining the vacuum state in the vacuum chamber 1 is formed and irradiated with the laser beam. However, as shown in FIG. An optical fiber 1b penetrating the vacuum chamber 1 is provided in a state in which the vacuum in the vacuum chamber 1 is maintained through an optical fiber connector or the like, and laser light from the excimer laser 3 is irradiated onto the target substrate 4 through the optical fiber 1b. You may comprise so that it may carry out.
(Second Embodiment)
In the second embodiment, solidified ozone is vaporized by raising the temperature of a target substrate, and an oxidation process is to be performed.
[0068]
Next, a second embodiment of the present invention will be described based on FIG. In FIG. 12, the same components as those in FIG. 6 are denoted by the same reference numerals, and description thereof is omitted. Further, illustration and description of the peripheral devices such as the XPS, the X-ray source, and the pump are omitted as in the first embodiment.
[0069]
In the figure, reference numeral 15 denotes a diffusion prevention chamber. The diffusion prevention chamber 15 is formed with the target substrate (sapphire substrate in this embodiment) 4 as the bottom and an opening 15a corresponding to the sample to be oxidized 14 above. The air outlet 12 of the transport pipe 2 is configured to communicate. As a material for forming the diffusion prevention chamber 15, for example, aluminum is preferable because it has good heat conduction and low reactivity with ozone. The diffusion prevention chamber 15 is thermally coupled to the copper block 5.
[0070]
First, similarly to the first embodiment, after solid ozone is adsorbed on the sapphire substrate 4, a gas other than ozone is removed.
[0071]
Next, the temperature of the sapphire substrate 4 is raised to a temperature at which the vapor pressure of ozone is increased by the heater 6, and the sample to be oxidized 14 is moved to the opening 15 a of the diffusion prevention chamber 15. The movement of the sample 14 to be oxidized is performed using a manipulator (not shown).
[0072]
Then, the temperature of the sapphire substrate 4 is raised to an appropriate temperature to vaporize ozone, and ozone gas is guided to the surface of the sample to be oxidized 14 to perform oxidation treatment. Since the supply amount of ozone molecules is uniquely determined by the vapor pressure of ozone gas, it can be set to an arbitrary value by adjusting the temperature of the sapphire substrate 4. The temperature of the sapphire substrate 4 is determined in consideration of the efficiency of oxidation, the balance of analysis equipment not shown, the load on the vacuum pump, and the like. This is less desirable because it only becomes reaction-limited on the surface of the oxidized sample 14. Regarding the temperature setting here, for example, based on the data indicating the pressure change after ozone adsorption shown in FIG. 2, as shown in FIG. 13, “temperature for adsorbing ozone on the substrate”, “temperature for increasing ozone purity” "," Temperature for supplying ozone gas to the sample to be oxidized "should be set to an appropriate temperature range.
[0073]
Note that when the vaporized ozone is introduced into the sample to be oxidized 14, the diffusion prevention chamber 15 thermally coupled to the copper block 5 is at a low temperature similar to the temperature of the sapphire substrate 4. Even if it collides with the inner wall surface of this diffusion prevention chamber 15, it is not decomposed into oxygen and is efficiently led to the sample to be oxidized 14 as ozone molecules.
[0074]
Further, since the diffusion prevention chamber 15 is almost completely cut off from the outside (inside the vacuum chamber 1), the sapphire substrate 4 and the sample to be oxidized 14 in the diffusion prevention chamber 15 are sprayed when ozone gas is blown onto the sample to be oxidized 14. A pressure difference shown in FIG. 14 is generated on the surface, and ozone molecules can collide with the sample to be oxidized 14 at a high speed.
[0075]
As described above, according to the oxidation processing apparatus according to the present embodiment, high-purity ozone gas can be efficiently supplied to the surface of the sample to be oxidized at an arbitrary speed. Since ozone gas is supplied to both the target substrate and the sample to be oxidized at a low temperature, the degree of vacuum in the vacuum chamber is not deteriorated compared to the case of supplying at room temperature, and problems such as adverse effects on peripheral devices are prevented. can do.
[0076]
【The invention's effect】
As described above, according to the present invention, it is possible to store a high-concentration ozone-containing gas by adsorbing solid ozone onto the target substrate, and the target substrate temperature after the solid ozone adsorption is changed to the ozone vapor pressure in the vacuum chamber. It is possible to remove the gas other than ozone adsorbed on the target substrate and raise the ozone concentration by raising the temperature to the same temperature.
[0077]
In addition, by using laser irradiation to vaporize solid ozone adsorbed on the target substrate by the storage method or apparatus of the present invention, an ozone beam with extremely high directivity and activity is supplied to the sample to be oxidized, for example, Even if the temperature of the oxidized sample is as low as room temperature, it is possible to perform an efficient oxidation process that can proceed with the initial oxidation at a high speed. Ozone decomposition can be suppressed to a minimum, and furthermore, by utilizing its high directivity, it is possible to oxidize a large-diameter sample to be oxidized or to finely process the surface.
[0078]
And even if the solid ozone adsorbed on the target substrate by the storage method or apparatus of the present invention is vaporized by raising the temperature of the target substrate, the oxidation treatment with high-purity ozone gas can be performed, and the diffusion prevention chamber is further provided. By providing it, high purity ozone gas can be efficiently supplied to the surface of the sample to be oxidized at an arbitrary speed. At this time, ozone gas is supplied to both the target substrate and the sample to be oxidized at a low temperature. The degree of vacuum in the vacuum chamber is not deteriorated compared to the case of supply, and problems such as adverse effects on peripheral devices can be prevented.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an experimental apparatus (a high-concentration ozone-containing gas storage apparatus) according to the present invention.
FIG. 2 is a graph showing a pressure change after ozone adsorption.
FIG. 3 is a graph showing the velocity distribution of ozone and oxygen.
FIG. 4 is a graph showing the velocity distribution of ozone when the laser power density is changed.
FIG. 5 is a graph showing the composition of emitted particles when the substrate temperature is changed.
FIG. 6 is a schematic configuration diagram of an oxidation processing apparatus according to the first embodiment of the present invention.
FIG. 7 is a graph showing the relationship between the ratio of ozone molecules to oxygen molecules and the laser energy density.
FIG. 8 is an explanatory diagram of surface oxidation of a sample to be oxidized using laser ablation.
FIG. 9 is an explanatory view of surface oxidation of a large-diameter sample to be oxidized using laser ablation.
FIG. 10 is a graph showing the relationship between the ablation area release ozone amount and the ozone beam density.
FIG. 11 is a schematic configuration diagram of an oxidation processing apparatus using another laser irradiation method according to the first embodiment of the invention.
FIG. 12 is a schematic configuration diagram of an oxidation processing apparatus according to a second embodiment of the invention.
FIG. 13 is a view showing the concept of a target substrate temperature control method.
FIG. 14 is a graph showing the pressure distribution between the target substrate temperature and the sample to be oxidized.
FIG. 15 is a schematic configuration diagram of a conventional oxidation treatment apparatus.
[Explanation of symbols]
1, 20 ... Vacuum chamber
2, 22 ... Transport pipe
3. Excimer laser
4 ... Target substrate (sapphire substrate)
5 ... Copper block
6 ... Heater
7 ... Cold head (refrigerator)
8 ... Thermometer
9 ... Mass spectrometer
10 ... Preamplifier
11 ... Oscilloscope
12 ... Outlet
13, 21 ... high purity ozone generator
14, 27 ... Oxidized sample
15 ... Diffusion prevention room
15a ... opening

Claims (19)

  A step of cooling a target substrate made of a material that is inert to ozone and has good thermal conductivity disposed in a vacuum chamber, and supplying the high-purity ozone gas to the target substrate by supplying a high-purity ozone gas onto the target substrate; Adsorbing as solid ozone on the substrate and stopping the supply of high-purity ozone gas and increasing the target substrate temperature until the ozone vapor pressure becomes the same as the pressure in the vacuum chamber. A method for storing a high-concentration ozone-containing gas, comprising a step of removing a gas other than ozone.   The method for storing a high-concentration ozone-containing gas according to claim 1, wherein in the step of removing a gas other than the ozone gas, the temperature of the target substrate is increased to 40 to 60K.   The said target substrate has translucency, The storage method of the high concentration ozone containing gas of Claim 1 or 2 characterized by the above-mentioned. The method for storing a high-concentration ozone-containing gas according to any one of claims 1 to 3 , wherein a sapphire substrate is used as the target substrate.   A target substrate made of a material that is inert to ozone and has good thermal conductivity, disposed in a vacuum chamber, cooling means for cooling the target substrate, and transport for supplying high-purity ozone gas onto the target substrate A high-concentration ozone-containing gas storage device comprising a tube and heating means for raising the temperature of the target substrate.   6. The high concentration ozone-containing gas storage device according to claim 5, wherein the target substrate has translucency.   The high-concentration ozone-containing gas storage device according to claim 5 or 6, wherein a sapphire substrate is used as the target substrate. A solid substrate surface stored by the method for storing a high-concentration ozone-containing gas according to any one of claims 1 to 4 is irradiated with laser light to perform ablation, whereby a target substrate and a target substrate are placed in the vacuum chamber. An oxidation treatment method comprising irradiating an ozone beam toward the surface of the sample to be oxidized which is disposed opposite to the surface.   9. The oxidation treatment method according to claim 8, wherein the laser light has a wavelength of 200 to 370 nm in the vicinity of ultraviolet light where ozone absorption is strong.   10. The oxidation method according to claim 8, wherein the oxidation region of the sample to be oxidized is adjusted by adjusting the aperture of the laser beam, the irradiation position, or the distance between the target substrate and the sample to be oxidized. . The solid ozone stored by the high-concentration ozone-containing gas storage method according to any one of claims 1 to 4 is increased to a temperature at which the ozone vapor pressure becomes higher than the vacuum chamber pressure. And oxidizing the ozone gas toward the surface of the sample to be oxidized which is disposed opposite to the target substrate in the vacuum chamber as ozone gas. A sample to be oxidized is disposed in a vacuum chamber of the high-concentration ozone-containing gas storage device according to any one of claims 5 to 7 so as to face the target substrate, and the target substrate surface is irradiated with laser light. An oxidation processing apparatus characterized in that a laser beam irradiation apparatus is provided.   The laser beam irradiation device is disposed outside a vacuum chamber, a window that transmits the laser beam to the vacuum chamber and maintains a vacuum state in the vacuum chamber is formed, and the laser beam from the laser beam irradiation device is transmitted to the window. The oxidation processing apparatus according to claim 12, wherein the target substrate is irradiated via a substrate.   The laser beam irradiation device is disposed outside the vacuum chamber, an optical fiber is provided that penetrates the vacuum chamber while maintaining a vacuum state in the vacuum chamber, and the laser beam from the laser beam irradiation device is transmitted through the optical fiber. The oxidation processing apparatus according to claim 12, wherein the target substrate is irradiated. In claims 5 to the vacuum chamber of the storage device of high-concentration ozone-containing gas according to any one of claims 7, oxidation treatment apparatus characterized by disposing the oxidized sample with the target substrate and the counter.   A diffusion prevention chamber having an opening corresponding to the sample to be oxidized is formed on the upper side with a material that is inert to ozone and has a good thermal conductivity with the target substrate as a bottom surface. The oxidation treatment apparatus according to claim 15, wherein the oxidation treatment apparatus is configured to communicate.   The oxidation processing apparatus according to claim 16, wherein aluminum is used as a material that is inert to ozone and has good thermal conductivity. Wherein in a vacuum chamber, oxidation processing apparatus according to any one of claims 12 to 17, characterized in that a moving means for moving the oxidized sample.   The oxidation processing apparatus according to claim 18, wherein a manipulator is used as the moving means.

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