JP2001102345A - Method and device for treating surface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem, where at least one of gases should be changed into plasma for generating chemical active species when a gas of molecules containing hydrogen, fluorine, and nitrogen atoms as components is used for treating the surface of an object to be machined, and to solve the expensive method and device for treating the surface by eliminating the need for a high-frequency or a microwave power supply required by the device. SOLUTION: A gas of molecules containing hydrogen atoms with relatively low connection energy, fluorine atoms, and nitrogen atoms as components is used, thus achieving generation of chemical active species by at least giving energy which is nearly equal to the heating of the gas, generating a compound required for treatment, and hence treating the surface of an object to be machined.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a gas comprising a molecule containing a hydrogen atom as a constituent element and a gas consisting of a molecule containing a fluorine atom as a constituent element, wherein at least one of the molecules contains a nitrogen atom together with a hydrogen atom or a fluorine atom. The present invention relates to the provision of a surface treatment method and apparatus using a mixture of molecules containing molecules as constituent elements or molecules of molecules containing nitrogen atoms as constituent elements, and using the mixed gas. In particular, in conventional surface treatment using a gas phase reaction, the gas used can be heated only by heating alone, without taking the technique of dissociating or ionizing the gas by high-frequency electromagnetic waves, which is often used to increase the reactivity of the gas used. Is characterized by increasing the reactivity thereof and performing a desired surface treatment. Also,
Another feature is that an inexpensive processing device can be supplied because high-frequency electromagnetic waves are not used.

[0002]

2. Description of the Related Art In the manufacturing process of ultra-large-scale semiconductor devices, which are currently being miniaturized, it is necessary to provide metal wiring in the structure of fine grooves and holes. It is indispensable to remove a natural oxide film present on a part of the silicon surface in order to secure good electric conduction.
In the conventional wet cleaning method for such cleaning, it is becoming difficult for the cleaning solution to enter the fine grooves and holes, and the desired cleaning cannot be achieved, resulting in good electric conduction. It has been pointed out that it is becoming difficult to obtain (Naoto Aoto et al.
Silicon Technology No. 6, 6 (1998)). In order to clean the surface having such a fine structure, a dry (dry) cleaning method in which the active species or compounds contributing to the cleaning can enter the fine grooves and holes more easily than in the case of the wet cleaning is advantageous. It is considered that there is a method that mainly uses the reducing property of hydrogen atoms generated by dissociating and generating hydrogen gas into plasma and a method using the reactivity of fluorine atoms generated by dissociating fluorine-based gas with plasma. Has been done. Among these, one of those using hydrogen atoms is one in which an object to be processed is processed in hydrogen plasma. However, this method causes damage to the surface of an object to be processed by high-energy particles such as ions and electrons in plasma, and thus is not suitable for manufacturing ultra-large-scale semiconductor devices with further miniaturization. As a method for avoiding this, a so-called hydrogen plasma down-flow process for processing an object to be processed at a position downstream of a plasma region is performed. However, in this method, outside the plasma region, hydrogen atoms easily recombine and return to hydrogen molecules mainly on the wall surface of the reaction vessel, and the hydrogen atom concentration in the downflow region where the object is placed is reduced. Because of the drastic reduction, no suitable practical method has been obtained. On the other hand, as a method using a fluorine-based gas, ammonia (NH ₃ )
Downflow treatment of a mixed gas of nitrogen and nitrogen trifluoride (NF ₃ ) (Nishino et al .: J. App.
l. Phys. 74 (1993) 1345), hydrogen (H
₂ ) and a plasma downflow treatment of a mixed gas of NF ₃ (T. Kutsuki et. Al .: Ext. Abst)
r. of ECS, Hawaii (1993) p. 37
It has been reported that the natural oxide film on the silicon surface can be removed. This is ammonium fluoride (NH ₄ F)
A species that etches a silicon oxide film such as is formed in the plasma and reaches the surface of the silicon substrate on which the silicon oxide is formed, which is installed in the downflow region of the plasma, and etches the oxide. Is believed to be However, in these treatment methods, fluorine atoms generated by dissociation from NF ₃ by the plasma reach the silicon surface which is the object to be treated, so that fluorine remains on the silicon surface from which the natural oxide film has been removed. The fluorine remaining on the silicon surface has an adverse effect on a thin film to be subsequently grown, which is not preferable in the manufacture of a very large-scale semiconductor device.

[0003] In recent years, it has been reported that a large amount of hydrogen atom concentration can be ensured downstream of the plasma by using a gas in which water vapor is mixed with hydrogen (J. Kik).
uchi et. al. : Jpn. J. Appl. Ph
ys. , 32, pp. 3120-3124 (199
3). ), A large amount of hydrogen atoms can be obtained even in the downflow region of hydrogen plasma. Then, by utilizing the reducibility of the hydrogen atoms obtained by this method, NF ₃ gas is added in a downflow region of hydrogen plasma,
It has been reported that a natural oxide film on the silicon surface can be removed by the reaction product, and that the silicon surface after the treatment is a hydrogen-terminated surface that is not easily oxidized again (J. Kikuchi).
et. al. : Jpn. J. Appl. Phys. ,
33, 2207-2211 (1994). ). In this method, it has been confirmed that no fluorine remains on the silicon surface after removing the natural oxide film. This is because NF ₃ is added in the downflow region of the hydrogen plasma, so that no fluorine atoms are generated from NF ₃ by the plasma.

[0004]

In the above-described dry cleaning technology in the process of manufacturing an ultra-large-scale semiconductor device, any of the above-mentioned processes uses microwaves or high-frequency waves to convert a gas into plasma, and utilizes active species generated there. is there. Therefore, this method requires a microwave or high-frequency power supply in a processing apparatus, and further requires a plasma discharge unit, so that the mechanism is complicated and inevitably expensive. Did not.

[0005]

From various attempts aimed at dry cleaning using plasma in an ultra-large-scale semiconductor device manufacturing process, in particular, in order to remove a natural oxide film from a silicon surface by dry processing, it is necessary to use fluorine. In addition to the above, it is understood that a molecular gas containing hydrogen and nitrogen atoms as constituent elements is required. This is because the compound etching the silicon oxide film is ammonium fluoride, and ammonium hexafluorosilicate ((NH ₄ ) ₂ SiF ₆ ) is deposited as a by-product on the silicon surface as the silicon oxide film is etched. You can tell from doing. Also, this fluorine, hydrogen,
In order to generate ammonium fluoride having a function of removing a silicon oxide film from a gas containing nitrogen, it is necessary to supply a chemically active species to these gases to generate them. These active species were generated by converting the to plasma. In the present invention, in order to make it possible to manufacture the device at low cost, as a method of generating this chemically active species, expensive high-frequency, without using a plasma that requires a microwave power source, at most gas It was noted that only the thermal energy of the degree of heating was used, and a gas that easily dissociated or excited by this thermal energy to generate active species was used. As such a gas, first, xenon difluoride (XeF ₂ ) is known to decompose spontaneously even at room temperature to release chemically active fluorine atoms, which particularly generate thermal energy. It is thought that it works as a fluorine atom source even if not added. From the thermodynamic data, the chemical bond energy (O
K), fluorine (F ₂ ), chlorine trifluoride (Cl
F ₃ ) and nitrogen trifluoride (NF ₃ ) each have 155
kcal / mol, 251 kcal / mol, 273k
Since the binding energy is relatively low at cal / mol, it is expected that these gases can be easily dissociated or thermally excited by applying thermal energy to them to produce chemically active species such as fluorine atoms. . At this time, a compound such as ammonium fluoride capable of etching silicon oxide is produced by reacting such an active species with a molecule containing a hydrogen atom or a nitrogen atom, and is supplied to the workpiece to be processed. It is believed that the desired treatment can be achieved at the surface.

[0006]

FIG. 1 shows an apparatus for performing a surface treatment according to the present invention. Reference numerals 1 and 2 denote gas supply devices containing hydrogen, fluorine and nitrogen atoms. The gas supplied from the gas supply device passes through a pipe wound with a heater 3 to a tank 5 where a workpiece 4 is placed. Be guided. At this time, the gas is heated in the piping section around which the heater 3 is wound, and a compound that etches silicon oxide such as ammonium fluoride is generated as chemically active species are generated. The compound is supplied through the diffusion plate 6 so that the compound is supplied uniformly on the surface of the workpiece. Reference numeral 7 denotes a table on which the workpiece is set, and the temperature of the workpiece can be adjusted by a heater or a refrigerant in order to keep the temperature of the workpiece constant and obtain a processing result with good reproducibility. Reference numeral 8 denotes an exhaust device from which gas in the tank is exhausted. Materials used for processing tanks and piping may be significantly corroded by the gases used, or by chemically activated species such as fluorine atoms or compounds that etch silicon oxides such as ammonium fluoride generated by heating. If not, ceramics such as quartz, aluminum oxide, silicon carbide, silicon nitride, and aluminum nitride, and metals such as stainless steel and aluminum may be used. However, in the case of using quartz, there is a risk of etching by a compound that etches silicon oxide generated after heating the gas. In this case, the quartz wall is heated to about 50 ° C. or more. Suppress the etching.

[0007]

[First Embodiment] Using the processing apparatus shown in FIG. 1, a silicon substrate on which a silicon oxide film is formed as a workpiece is placed on a processing table to perform actual processing. At this time, ammonia and xenon difluoride were supplied from a gas supply source at a partial pressure ratio of 9: 1, the pressure was 10 Torr, the gas and the workpiece were not heated or cooled, and the treatment was performed at room temperature for 5 minutes. Was. FIG. 2 shows the difference between the infrared absorption spectra before and after the treatment. From this, it can be seen that an absorption peak appears upward at around 1100 cm ⁻¹ . This indicates that the silicon oxide film formed on the surface of the workpiece is etched by this process. In fact, ellipsometry revealed that the silicon oxide film was etched by about 10 nm. In FIG. 2, 3
^{300cm -1,} 1400cm ^-1, stretching vibration and deformation vibration of bonds each nitrogen atom and a hydrogen atom in the vicinity of 700 cm ^-1, and an absorption peak derived from stretching vibration of a bond of silicon and fluorine are observed. This was observed because ammonium hexafluorosilicate, which is a by-product accompanying the etching of silicon oxide by this treatment, was deposited on the surface of the workpiece. Such deposits can be easily removed by increasing the temperature of the workpiece to about 50 ° C. in a vacuum or an inert gas atmosphere such as nitrogen or argon, following the above-described silicon oxide etching treatment. Was confirmed by infrared absorption measurement. Removal of by-products deposited on the workpiece surface due to such etching,
Although the temperature was raised by increasing the temperature of the work table of the apparatus shown in FIG. 1, the temperature of the work may be increased by irradiating light for quick removal, The tank equipped with the mounting table is connected to the processing tank as shown in FIG. 1, and after removing the silicon oxide from the surface of the workpiece in the processing tank, the mounting table heated is removed. The heat treatment may be performed immediately after the workpiece is transported to the equipped tank.

Second Embodiment Using the processing apparatus shown in FIG. 1, a silicon substrate on which a silicon oxide film is formed as a workpiece is placed on a processing table to perform processing. At this time, ammonia and nitrogen trifluoride are supplied from a gas supply source at a partial pressure ratio of 1: 9, the pressure is 10 Torr, and after mixing the gas, the gas is heated by a heater wound around a pipe, and then the surface of the workpiece is applied. Lead. The processing time is one minute. FIG. 3 shows the temperature dependence of the heater used to heat the gas having the thickness of the silicon oxide film formed on the surface of the workpiece etched by this process. This shows that the thickness of the silicon oxide to be etched increases as the heater temperature increases. This is because the generation of active species such as fluorine atoms is promoted by the thermal decomposition and thermal excitation of nitrogen trifluoride as the heater temperature rises, and as a result this reacts with ammonia to form silicon oxide such as ammonium fluoride. It is considered that the thickness of the silicon oxide material to be etched is increased because the amount of the compound that etches the material is increased. Although it depends on the partial pressure ratio between ammonia and nitrogen trifluoride, particularly, the partial pressure ratio between nitrogen trifluoride and nitrogen trifluoride is 9%.
It was confirmed that the etching of silicon oxide was possible when the temperature of the heater for heating the gas was about 300 ° C. when that of ammonia was 1.

FIG. 4 shows the etching of the silicon oxide on the surface of the workpiece when the processing is performed for 1 minute at a temperature of 700 ° C. and a pressure of 10 Torr of a heater for heating the gas by mixing ammonia and nitrogen trifluoride gas. It shows the dependency of the partial pressure ratio of nitrogen trifluoride on the mixed gas of ammonia and nitrogen trifluoride having different thicknesses. From this, it is understood that the etching amount of silicon oxide tends to increase as the partial pressure ratio of nitrogen trifluoride increases. This is because the amount of active species such as fluorine atoms generated by the decomposition of nitrogen trifluoride or thermal excitation increases with the heating of the mixed gas, and as a result they react with ammonia to produce silicon oxide. This is probably because the amount of the compound to be etched was increased. However, when ammonia is not supplied and only nitrogen trifluoride is supplied, the silicon oxide is not etched. This is presumably because even if an active species such as a fluorine atom is generated from nitrogen trifluoride, a compound for etching a silicon oxide such as ammonium fluoride cannot be generated because ammonia does not exist. .

A silicon oxide having a thickness of about 1 nm is formed on a silicon substrate in a mixed solution of sulfuric acid and hydrogen peroxide, and the state of the silicon substrate surface after the silicon oxide is removed by the method of the present invention is changed to red. It was examined by external absorption spectroscopy. Using the apparatus shown in FIG. 1, the partial pressure ratio between ammonia and nitrogen trifluoride is 1: 1, and the pressure is 10 Torr.
r, the temperature of the heater wound around the pipe was 800 ° C. for 10 minutes. FIG. 5 shows an infrared absorption spectrum in a wave number range in which infrared absorption derived from a bond between a silicon atom and a hydrogen atom appears. The spectrum of (a) is the infrared absorption spectrum of the silicon substrate surface after the treatment of the present invention, and the spectrum of (b) is the 1% hydrofluoric acid (HF) solution treatment to remove the silicon oxide. Is shown. Comparing the spectra of the two, it can be seen that the shapes and the intensities are substantially equal to each other. It has been clarified that the surface of a silicon substrate treated with a hydrofluoric acid solution is terminated with hydrogen (T. Takah).
agi et al. : J. Appl. Phys. 64,
(1988) 3516. This indicates that the surface of the silicon substrate is terminated with hydrogen by the treatment of the present invention.

Other gas combinations, ie, xenon difluoride and hydrogen and nitrogen, nitrogen trifluoride and hydrogen, fluorine (F
₂ ) Etch silicon oxide with ammonia, fluorine, nitrogen and hydrogen, chlorine trifluoride and ammonia, chlorine trifluoride and nitrogen and hydrogen in the same manner as in the above-mentioned mixed gas of nitrogen trifluoride and ammonia. I was able to. In any of these, an active species such as a fluorine atom is generated by warming a compound containing fluorine (nitrogen trifluoride, fluorine, chlorine trifluoride), and this reacts with a molecule containing a nitrogen or hydrogen atom to produce fluorine. It is considered that a compound that etches a silicon oxide such as ammonium fluoride is generated. When xenon difluoride is used, it is not necessary to particularly heat it. When the treatment of the present invention is applied to the removal of silicon oxide formed on a silicon substrate in sulfuric acid and hydrogen peroxide using a combination of these gases, the silicon substrate surface after the treatment is terminated with hydrogen. Confirmed by infrared absorption spectroscopy.

[Third Embodiment] FIG. 5 shows an apparatus obtained by slightly modifying the apparatus shown in FIG. That is, a heater provided for heating the gas was installed downstream of the 12 gas supply systems. Then, ammonia is supplied from the gas supply system of 11 and nitrogen trifluoride is supplied from the gas supply system of 12, and the pressure is 10 To
rr, gas partial pressure ratio 1: 1, 13 heater temperature 700
The workpiece with the silicon oxide formed on the surface was treated at 1 ° C. for 1 minute. Thereafter, the surface of the workpiece was evaluated by infrared spectroscopy and ellipsometry, and it was found that the silicon oxide was etched. This means that heating the gas is necessary to generate active species, such as fluorine atoms, which react with molecules containing nitrogen and hydrogen atoms to produce compounds that etch silicon oxide, such as ammonium fluoride. In some cases, it is not necessary. Therefore, active species such as fluorine atoms are converted to nitrogen trifluoride, fluorine,
If chlorine trifluoride is produced by heating and then reacted with molecules containing nitrogen or hydrogen (nitrogen, hydrogen, ammonia, etc.) to produce a compound that etches silicon oxide, the desired treatment is Can be achieved.

[Fourth Embodiment] FIG. 6 shows a modification of the diffusion plate of the apparatus shown in FIG. That is, 22 heaters were embedded in a quartz disk having a large number of 21 through-holes, and used to heat the gas and uniformly diffuse the compounds necessary for the resulting processing. FIG. 7 shows a case where the piping is heated to 700 ° C. by a heater at a partial pressure ratio of nitrogen trifluoride and ammonia of 6: 4 and a pressure of 10 Torr as in the apparatus shown in FIG. 1, and a heater is embedded as shown in FIG. The figure shows the etching amount when the silicon oxide formed on the silicon substrate is treated for 1 minute when the diffusion plate is heated to 700 ° C. in the same manner. This shows that the amount of etching is larger when the diffusion plate is heated than when the pipe is heated four times or more. This is because, in the case of the diffusion plate, the area where the heated portion and the gas are in contact with each other is large compared to the case where the pipe is heated because a large number of through-holes are open, so that the silicon oxide is efficiently used. It is considered that a compound that etches was formed.
Therefore, in order to increase the area of the heated portion as much as possible, it is necessary to heat the gas over a long area of the pipe, or to heat the gas by inserting several diffusion plates as shown in FIG. 6 into the pipe. As a result, a compound capable of efficiently etching silicon oxide can be generated.

Fifth Embodiment In order to confirm whether or not the silicon oxide removing method of the present invention can be applied to an actual ultra-large-scale integrated circuit manufacturing process, as shown in FIG. 32 formed BP of about 0.6 μm thickness
SG (boron phosphorous silicone)
(a glass, silicon oxide to which boron or phosphorus is added) A hole having a diameter of 0.4 μm is formed using a reactive ion etching method (aspect ratio of hole: 1.5, aperture ratio: 30%). Growing on the silicon substrate surface at the bottom of the hole 3
An attempt was made to remove a native oxide of silicon having a thickness of about 2.5 nm. As described above, unless the native oxide at the bottom of the hole is removed, good electrical contact cannot be obtained between the silicon substrate and the conductive material to be buried in the hole, which poses a problem.
Using the apparatus shown in FIG. 1, the partial pressure ratio between ammonia and nitrogen trifluoride, 99: 1, and the temperature of the heater wound around the pipe 800
The treatment was performed at a temperature of 1 ° C. and a pressure of 1 Torr for 10 minutes. During the processing, the temperature of the workpiece was kept at room temperature. FIG. 9 shows the results obtained by X-ray photoelectron spectroscopy before (a), immediately after (b), and after processing the workpiece in a nitrogen atmosphere of 1 Torr at 100 ° C. for 5 minutes (c). Silicon 2p
₃ shows a _3/2 photoelectron spectrum. Looking at the spectrum of (a), the spectrum of the photoelectrons emitted from the silicon in the silicon substrate is observed around 48 eV of the binding energy, and exists on the surface of the silicon substrate at the bottom of the hole near the binding energy of 52.5 eV. A spectrum of photoelectrons emitted from silicon atoms in the natural oxide of silicon is observed. The thickness of the silicon native oxide at the bottom of the hole estimated from the intensity ratio of the two spectra was about 2.5 nm. In each of the spectra shown in FIG.
In order to separate the photoelectron spectrum emitted from the silicon atoms in the G film from the spectrum of the photoelectrons emitted from the natural oxide film at the bottom of the hole or from the silicon atoms in the silicon substrate, a voltage of -50 V is applied to the workpiece. Since the measurement was carried out while applying the voltage, _50p from the position where the silicon 2p _3/2 photoelectron spectrum originally appears
A spectrum is observed at a lower binding energy as eV. Next, looking at the spectrum after the treatment of (b), in addition to the spectrum of the photoelectrons emitted from the silicon atoms in the silicon substrate at the bottom of the hole, the etching energy of silicon oxide is increased to around 53.5 eV due to the etching. A spectrum of photoelectrons emitted from silicon atoms in the generated ammonium hexafluorosilicate is observed. The deposited film formed on such a surface is easily removed by a heat treatment at about 100 ° C., as is apparent from the photoelectron spectrum of (c). At this time, the silicon atoms in the silicon native oxide at the bottom of the hole are removed. No photoelectron spectrum is observed, indicating that such native oxide has been removed by this treatment, and the silicon substrate surface at the bottom of the hole is terminated with hydrogen. The shape of the hole before and after the treatment was examined with a scanning electron microscope, and there was almost no difference between the two. Normally, when silicon oxide at the bottom of a hole is formed using a solution of hydrofluoric acid (HF), the BPSG film forming the side wall of the hole is thermally oxidized in a dry oxygen atmosphere to form a thermal oxide film formed on a silicon substrate. The etching rate is several to ten and several times faster than the etching rate. Therefore, when the silicon oxide at the bottom of the hole having the structure shown in FIG. 8 is removed, the BPSG film on the side wall is also etched along with the removal of the natural oxide, and as a result, the diameter of the hole increases. There was a problem. FIG. 10 shows the temperature dependence of the amount of etching of the heater wound around the pipe when the BPSG film and the silicon thermal oxide film are treated by the method of the present invention using the apparatus of FIG. The treatment conditions were the partial pressure ratio of ammonia and nitrogen trifluoride,
The temperature at the time of processing the workpiece is 1: 9, the pressure is 10 Torr, and the processing time is 1 minute. From this, it can be seen that the etching amount of the BPSG film and the silicon thermal oxide film increases as the heater temperature of the piping increases, but there is no difference in the etching amount between the two, and the selectivity is almost 1. Therefore,
When the silicon oxide at the bottom of the hole as shown in FIG. 8 is removed by the method of the present invention, the diameter of the hole is suppressed from being larger than when using a hydrofluoric acid-based solution. It is possible to remove silicon oxide at the bottom of the hole.

[Sixth Embodiment] The apparatus shown in FIG. 1 is used to etch a silicon thermal oxide film formed on a silicon substrate by heating a stage on which a workpiece is set to about 50.degree. I went there. The processing conditions are a partial pressure ratio of ammonia and nitrogen trifluoride of 1: 9, a pressure of 10 Torr, and a heater temperature of 700 ° C. wound around a pipe. When the etching amount of the silicon oxide was examined by ellipsometry after the treatment, it was found to be 8.2 nm. Further, when the surface state of the processed workpiece was examined by infrared spectroscopy and X-ray photoelectron spectroscopy, ammonium hesafluorosilicate generated during etching of the silicon oxide was not observed. This is because the processing was performed by raising the temperature of the workpiece to about 50 ° C., so that ammonium hexafluorosilicate generated by etching of the silicon oxide was sublimated immediately from the surface without depositing on the surface. Conceivable. Therefore, by performing the treatment by raising the temperature of the workpiece in this manner, the silicon oxide can be etched while suppressing the deposition of ammonium hexafluorosilicate generated on the surface of the silicon oxide on the surface of the silicon oxide. This is because the step of removing the ammonium hexafluorosilicate deposit by heating the workpiece, which was necessary when the temperature of the workpiece is room temperature, performs the treatment of the present invention while heating the workpiece. This indicates that this is not always necessary.

Seventh Embodiment Using the apparatus shown in FIG. 1, the dependence of the etching amount of a silicon thermal oxide film formed on a silicon substrate on the temperature of a table on which a workpiece is placed was examined.
The processing conditions were a partial pressure ratio of ammonia and nitrogen trifluoride of 1: 9, a pressure of 10 Torr, and a heater temperature of 700 wound around the pipe.
° C and a processing time of 1 minute. FIG. 12 shows the result. From this figure, it can be seen that the lower the temperature of the workpiece, the greater the amount of silicon oxide to be etched. This indicates that adsorption of a compound for etching a silicon oxide such as ammonium fluoride generated on the surface of the workpiece determines the amount of etching. Therefore, it can be seen that controlling the temperature of the workpiece to obtain the desired etching characteristics is very effective.

[0017]

As described above, in an ultra-large-scale semiconductor device manufacturing process, a conventional apparatus and method for removing a native oxide on a silicon surface by a dry treatment can reduce the reactivity of a used gas by using high-frequency plasma. While the apparatus was complicated and expensive because of the attempt to obtain, the present invention achieved the reactivity of the gas by heating the gas at most, so the apparatus was simple and inexpensive. However, the same effect as the conventional method could be obtained.

[Brief description of the drawings]

FIG. 1 is a view showing an apparatus for performing a surface treatment method of the present invention.

FIG. 2 is a diagram showing an infrared absorption spectrum of a workpiece after applying the surface treatment method of the present invention to the workpiece on which a silicon oxide is formed on a silicon substrate.

FIG. 3 is a diagram illustrating a case where a surface treatment method of the present invention is applied to a workpiece on which a silicon oxide is formed on a silicon substrate; FIG. 4 is a diagram showing the heater temperature dependence.

FIG. 4 shows the dependence of the etching amount of silicon oxide on the partial pressure ratio between ammonia and nitrogen trifluoride when the surface treatment method of the present invention is applied to a workpiece having silicon oxide formed on a silicon substrate. FIG.

FIG. 5 is a diagram illustrating an infrared absorption spectrum of a silicon substrate surface after the silicon oxide has been removed by applying the surface treatment method of the present invention to a workpiece having a silicon oxide formed on the silicon substrate. FIG.

FIG. 6 is a diagram showing an apparatus for performing the surface treatment method of the present invention.

FIG. 7 is a diagram showing components for heating and diffusing a gas in an apparatus for performing the surface treatment method of the present invention.

FIG. 8 is a diagram showing the effects of the components for heating and diffusing the gas shown in FIG. 7 in an apparatus for performing the surface treatment method of the present invention.

FIG. 9 is a diagram showing the structure of holes on the surface having fine holes to which the surface treatment method of the present invention is applied.

FIG. 10 is a diagram showing a silicon 2p _3/2 photoelectron spectrum obtained by X-ray photoelectron spectroscopy of the surface when the surface treatment method of the present invention is applied to a surface having fine holes.

FIG. 11 illustrates a case where the surface treatment method of the present invention is applied to a workpiece in which a thermal silicon oxide or a BPSG film is formed on a silicon substrate; Is a diagram showing the temperature dependence of a heater wound around a pipe for the purpose.

FIG. 12 shows the dependence of the etching amount of silicon oxide on the temperature of a stage on which a workpiece is placed when the surface treatment method of the present invention is applied to a workpiece in which silicon oxide is formed on a silicon substrate. FIG.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 gas supply device 2 gas supply device 3 heater 4 workpiece 5 tank 6 diffusion plate 7 units 8 exhaust device 11 gas supply device 12 gas supply device 13 heater 14 workpiece 15 tank 16 diffusion plate 17 units 18 exhaust device 21 quartz Plate 22 Heater 31 Silicon substrate 32 BPSG film 33 Silicon native oxide

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hiroki Ogawa 2-18-18 Shin-Yokohama, Kohoku-ku, Yokohama, Kanagawa 1st Century Shin-Yokohama Room 701 (72) Inventor Tomoharu Arai 1-6-6 Shinmeicho, Higashimatsuyama-shi, Saitama ( 72) Inventor Takanori Ichiki 1-25-25 Chiyoda, Sakado-shi, Saitama, Japan No. 201, Sanhitsu Kiyoshi Room 201 (72) Inventor Jun Kikuchi 2-14-6, Shirokanedai, Minato-ku, Tokyo

Claims (14)

[Claims] At least one of a gas consisting of a molecule containing a hydrogen atom as a constituent element and a gas consisting of a molecule containing a fluorine atom as a constituent element is a molecule containing a nitrogen atom as a constituent element together with a hydrogen atom or a fluorine atom. so,
A surface treatment method and apparatus, comprising: after mixing these gases, treating a workpiece placed downstream thereof. 2. A gas comprising a molecule containing a hydrogen atom as a constituent element, a gas containing a molecule containing a fluorine atom as a constituent element, and a nitrogen (N ₂ ) gas are mixed, and then a workpiece placed downstream thereof is treated. A surface treatment method and apparatus. 3. A gas comprising a molecule containing a hydrogen atom as a constituent element and a gas consisting of a molecule containing a fluorine atom as a constituent element, or a nitrogen gas according to claim 1 or 2, followed by heating the mixed gas. And a surface treatment method and apparatus for treating a workpiece placed downstream thereof. 4. A gas comprising a molecule containing a fluorine atom as a constituent element according to claim 1 or 2 is heated and mixed with a gas comprising a molecule containing a hydrogen atom as a constituent element or a nitrogen gas downstream thereof. A surface treatment method and apparatus, further comprising treating a workpiece placed downstream thereof. 5. A surface treatment method and apparatus, wherein the molecule containing a hydrogen atom as a constituent element according to claim 1 is hydrogen (H ₂ ) or ammonia (NH ₃ ). 6. The molecule containing a fluorine atom as a constituent element according to claim 1 is preferably xenon difluoride (Xe).
F ₂ ), fluorine (F ₂ ), nitrogen trifluoride (NF ₃ ), or chlorine trifluoride (ClF ₃ ). 7. A surface treatment method and apparatus, wherein the workpiece according to claim 1 is a substance containing silicon oxide as a main component. 8. A method and apparatus for processing a workpiece, wherein the processing of the workpiece is performed while the temperature of the bath for performing the surface treatment of the workpiece according to claim 1 is increased. 9. The method according to claim 1, wherein the workpiece is cooled.
Alternatively, a surface treatment method and apparatus, wherein a workpiece is processed while heating and controlling the temperature. 10. A surface treatment method and apparatus according to claim 9, wherein cooling or heating of the workpiece is performed by controlling light or the temperature of a table on which the workpiece is placed. 11. A surface treatment method and apparatus according to claim 3, wherein said gas is heated by heating a pipe for introducing said gas. 12. A heating element according to claim 3 or 4, wherein a heating element having a large surface area is provided in a pipe for introducing these gases or in a tank for processing a workpiece. And a surface treatment method and apparatus which are performed by passing a gas therethrough. 13. After the surface treatment of the workpiece according to any one of claims 1 to 4, the temperature of the workpiece is increased in an inert gas atmosphere such as nitrogen or in a vacuum, and the workpiece is processed. A surface treatment method and apparatus for removing by-products deposited on an object surface. 14. The heat treatment of the workpiece after the surface treatment of the workpiece according to claim 13 is performed in a tank in which the workpiece is processed or a tank in which the workpiece is processed. A surface treatment method and apparatus, wherein the treatment is performed in a tank provided via a partition.