JP2981243B2 - Surface treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a surface treatment technique for a substrate to be processed which can be used for manufacturing a semiconductor device, and particularly relates to a substrate having an oxide film on the surface. The present invention relates to a surface treatment technique for dry etching or removing the oxide film of a treatment substrate.

(Prior Art) Conventionally, when manufacturing a semiconductor element having a semiconductor substrate such as silicon, a natural oxide film formed on a surface of the substrate or a semiconductor film or a metal film on the substrate has been a problem. This natural oxide film is easily formed by exposing the substrate to the atmosphere or transferring the substrate between manufacturing apparatuses. The natural oxide film is a very thin film (for example, a natural oxide film of silicon has a thickness of 5 to 20 ° and an oxide film of 2 to 3 atomic layers), and this film greatly affects a semiconductor device manufacturing process or device characteristics. Affect.

For example, selective etching in which a material formed on a semiconductor substrate or the like is selectively etched away from a different material such as a silicon oxide film, or a specific portion of a substrate surface of a semiconductor substrate or the like, for example, only contact holes and through holes This is a problem in a manufacturing process such as selective CVD in which a film is selectively deposited on the substrate.

That is, since the selective etching and the selective CVD are performed by utilizing the difference in the properties of different kinds of materials, for example, a semiconductor such as silicon or the like by using electrically neutral atoms and molecules in the selective etching. When etching a metal such as nitride or aluminum and their oxides, silicon, aluminum chlorine gas, and silicon nitride are easily etched by a mixed gas of chlorine and fluorine.
These oxides are not etched at all and can be selectively etched. However, if a natural oxide film is formed on the surface of the semiconductor or metal, the selectivity is lowered, and good selective etching cannot be performed.

In addition, recently, there has been known an apparatus using a magnetron type reactive ion etching apparatus having a cooling means for a substrate for performing highly selective etching, and performing etching while cooling the substrate by the cooling means. This is because, for example, when a silicon substrate is selectively etched with respect to a silicon oxide film by using a chlorine-based gas, SiCl ₄ as an etching product or SiCl _x (x = 1 to 3) generated by decomposition of the etching product by magnetron plasma. ) Is based on the fact that adsorption tends to occur on the surface of a silicon oxide film having polarity, and this serves as an adsorption layer, which suppresses etching, while utilizing the fact that an adsorption layer is unlikely to be formed on a silicon substrate, thereby achieving highly selective etching. It is done. Also in this case, if a natural oxide film is formed on the silicon substrate, the selectivity is reduced.

Also, in the case of selective CVD, if the substrate temperature is kept at an appropriate level using, for example, WF ₆ and a hydrogen gas or a silane-based gas, the gas reacts with silicon or a metal surface, and tungsten is deposited. Selective CVD is achieved by utilizing the fact that no reaction occurs and does not deposit on it.
Also in this case, if there is a natural oxide film on the silicon or metal surface, the selectivity is lowered and good selective CVD cannot be performed.

Further selection for the contact holes and through holes
When wiring and electrode materials are buried by CVD, there is a problem that the resistance increases if a natural oxide film is present, and the high-speed operation of the device is deteriorated.

Such a problem of the decrease in selectivity is particularly remarkable in a process mainly based on a chemical reaction, but also in a process in which a physical action of giving ions and energy to a chemical reaction such as reactive ion etching is added. Occurs.

When a natural oxide film is formed on such a substrate surface, there is a problem that the selectivity cannot be obtained in etching or deposition, and good etching or deposition cannot be performed. No processing has been performed. However, in order to perform more selective etching and deposition along with miniaturization of elements in the future, a technique capable of easily removing the natural oxide film is desired.

Furthermore, it is also a problem that the natural oxide film is formed on the surface of the substrate in oxidation, epitaxial growth, vapor phase diffusion, and the like in other manufacturing processes such as etching and CVD.

That is, in the formation of an oxide film, particularly in the formation of a gate oxide film, high quality and uniform thickness of the film are required. However, if a natural oxide film is present before the oxide film is formed by a high-temperature heat treatment, a gate oxide film is formed while taking in the natural oxide film having a poor film quality generated at room temperature, and the film quality is deteriorated. Since the thickness of the natural oxide film is not uniform and has no reproducibility, there is a problem that the thickness of the subsequently formed gate oxide film is also uneven.

When epitaxial growth is to be performed on a substrate such as silicon, a good silicon film cannot be obtained unless the surface of the substrate is in a clean state without a natural oxide film. Actually, after removing organic contaminants and metal contaminants by wet cleaning as a pretreatment, the inside of the epitaxial apparatus is set to a high vacuum, and heated while flowing hydrogen chloride or hydrogen gas to convert the natural oxide film to silicon monoxide. However, there has been a problem that contaminants are detached from the vessel wall of the apparatus and adhere to the substrate during the heating.

Furthermore, when impurities such as arsenic and phosphorus are diffused into a substrate such as silicon by vapor phase or solid phase diffusion, if a natural oxide film is present on the surface, it becomes a barrier and the diffusion rate is high. There was a problem of lowering.

As described above, the natural oxide film is not limited, and the oxide film on which the semiconductor device manufacturing process is formed may be etched or removed.

For example, in a DRAM, a so-called trench capacitor forming technique of forming a groove in a silicon substrate so as to reduce the occupied area without reducing the capacity and providing an oxide film on the surface thereof has been performed. Here, in order to avoid dielectric breakdown due to electric field concentration at the corners of the groove, once oxidized (sacrificial oxidation) at a high temperature of 900 ° C. or higher, an oxide film is peeled off to eliminate the surface roughness of the groove and reduce the angle. After rounding the portion, there is a process for forming a new oxide film to prevent electric field concentration at the corner. In this case, it is desired that the oxide film is selectively removed without damaging the underlying silicon substrate.

Further, when an electrode is formed on the inner wall of the groove of the silicon substrate, a silicon oxide containing an impurity is deposited by a CVD method and then heated to diffuse the impurity into the silicon substrate. After the diffusion, it is desired that the silicon oxide be selectively removed without damaging the underlying silicon substrate as described above.

Alternatively, even when an oxide film is formed on a base such as a silicon substrate and a part of the oxide film is etched to form a contact hole or a through hole, the etching of the oxide film is performed so that the contact resistance does not increase. An etching process that does not damage the underlying substrate is required.

Furthermore, an oxide such as silicon may adhere to the back surface of the substrate to be processed or the inner wall of the processing container of the substrate to be processed due to the repetition of the process. For example, when a silicon-based deposition gas is introduced into the processing container, the above-described oxide is peeled off and becomes dust, adheres to the substrate to be processed, and lowers the yield. It is desired that the oxide be easily removed before the removal.

The oxide must be removed because it contains a metal, heavy metal, or the like, or becomes thick when exposed to the air for a long time. This oxide is usually removed by wet treatment with hydrofluoric acid or an ammonium hydrofluoride buffer. According to this, the oxide can be selectively removed from silicon or the like without damaging the base.

However, in the above-mentioned wet treatment, the liquid cannot easily be removed from the oxide inside the groove having a high aspect ratio (ratio of the depth to the opening diameter) due to surface tension, and cannot be removed. Silicic acid is produced as a reaction product by the treatment, and if the subsequent pure water rinsing is insufficient, the silicic acid becomes a colloid and remains as a stain on the substrate surface. Alternatively, the above-mentioned hydrofluoric acid and ammonium hydrofluoride buffer have a problem that they are highly toxic and difficult to handle. Furthermore, after the wet processing, the substrate to be processed is usually exposed to the atmosphere, so that a natural oxide film is formed again.

Alternatively, as a method for solving the problem caused by the wet treatment, the oxide may be removed by a dry treatment using a gas. For example, oxides such as silicon can be etched by fluorine atoms. However, the fluorine atoms are also etched in silicon and metals, and sufficient selectivity cannot be obtained.

(Problems to be Solved by the Invention) As described above, when performing selective etching or selective CVD in the manufacture of a semiconductor device, the selectivity is reduced due to a natural oxide film formed on a substrate, and the resistance of the device is reduced. Therefore, it is desired to remove the natural oxide film, and it is also desired to remove the natural oxide film in manufacturing processes such as oxidation, epitaxial growth, and diffusion.

When etching or removing not only a natural oxide film but also an oxide film formed in a manufacturing process, it is desired to selectively remove only the oxide film by dry treatment without damaging the base. .

The present invention solves the above-mentioned conventional problems,
It is an object of the present invention to provide a surface treatment method and apparatus capable of favorably etching or removing a natural oxide film or another oxide.

[Configuration of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a reaction vessel capable of evacuating a substrate to be processed having an oxide film formed on a substrate surface, and a halogen salt in the reaction vessel. A surface treatment apparatus having a gas introduction means for introducing a gas (first invention), a reaction vessel capable of evacuating a substrate to be treated having an oxide film formed on a substrate surface, a gas containing a halogen element and a basic A surface treatment apparatus comprising: an activating means for activating at least one of the gases in a region different from the reaction vessel; and a means for introducing the gas activated by the activating means into the reaction vessel ( Second invention), a substrate to be processed is housed, and the substrate to be processed is etched,
A processing chamber for performing processing such as deposition, oxidation, diffusion, and epitaxial growth; and means for supplying a halogen salt gas for removing an oxide film on the surface of the substrate to be processed before or after processing in the processing chamber. A surface treatment apparatus (third invention), a processing chamber for accommodating a substrate to be processed and processing the substrate to be etched, deposited, oxidized, diffused, and epitaxially grown; Activating means for activating at least one of the basic gases in a region different from the reaction vessel; and activating the gas activated by the activating means in the reaction vessel before or after processing in the processing chamber. A surface treatment apparatus (fourth invention), characterized in that a substrate to be treated having an oxide film formed on the surface of the substrate is housed in a reaction vessel capable of evacuating, and a halogen salt gas is provided. (Fifth invention), wherein an oxide film on the substrate to be processed is removed by feeding the substrate into the reaction vessel to remove the oxide film from the substrate to be processed. In a reaction vessel, at least one of a gas containing a halogen element and a basic gas is excited in a region different from the reaction vessel and the gases are supplied into the reaction vessel to provide an oxide film on the substrate to be processed. (Sixth invention).

In addition, the present invention provides a method in which a substrate to be processed having a metal or semiconductor oxide film formed on the surface of the substrate is housed in a reaction vessel, and a first gas containing a halogen element and any one of O, S, and C elements are used. At least one of a second gas containing any one of a single gas or a mixed gas of an inorganic compound containing a hydrogen element, or an organic compound gas containing a C or H element only as a constituent element or an O element as a constituent element A surface treatment method (seventh invention) characterized in that one of them is excited in a different region from the reaction vessel, and those gases are supplied into the reaction vessel to remove an oxide film on the surface of the substrate (seventh invention). A substrate to be processed having a metal or semiconductor oxide film formed on the surface of the substrate is housed in a reaction vessel and contains a first gas containing a halogen element, and any one of O, S and C and a hydrogen element A single gas or a mixture of inorganic compounds, Is Rui is constituent element C, only H elements, or O as a constituent element
An organic compound gas containing an element, a second gas containing any of the following gases, an O element or a halogen element, and S, C, B, N, P,
At least one gas out of the third gas containing any element of As is excited in a region different from the reaction vessel, and the first gas, the second gas, and the third gas are subjected to the reaction. An eighth aspect of the present invention provides a surface treatment method characterized by removing the oxide film on the surface of the substrate by supplying it into a container.

(Function) According to the first to third aspects of the present invention, a halogen salt is generated by a gas containing a halogen element and a basic gas, and this reacts with an oxide film of an object to be processed, or the halogen salt gas is directly converted into an oxide film. , The oxide film can be selectively etched and removed without damaging the underlayer.

According to the fourth and fifth aspects of the present invention, a single gas or a mixed gas of a first gas containing a halogen element and an inorganic compound containing any of O, S, and C and a hydrogen element is used. Exciting at least one of the second gas, in which the element is only C, H or an organic compound gas containing the O element in the constituent element, in a region different from the reaction vessel;
These gases are supplied into a reaction vessel in which a metal or semiconductor oxide film is formed on the substrate surface, or the first gas,
The second gas, and an O element or a halogen element and S,
Exciting at least one gas of the third gas containing any element of C, N, P, As in a region different from the reaction vessel and supplying those gases into the vessel, By reacting the oxide film, the oxide film can be selectively etched and removed without damaging the base.

(Example) 1st Example First, the 1st invention of this application is demonstrated with one Example. FIG. 1 is a schematic diagram of a surface treatment apparatus according to an embodiment of the first invention of the present application. The main part of this device is a vacuum vessel
11, a sample table 12 for mounting a sample 18 in the container, gas inlets 13a and 13b into which gas is introduced, and a quartz discharge tube for discharging gas introduced from the gas inlet 13a. 14 and
It comprises a gas exhaust port 15 for exhausting gas introduced into the container, and an exhaust gas treatment device 16 for removing toxic components of the exhausted gas. Further, the vessel 11 is provided with a quartz window 17 for irradiating the sample 18 with light and a means for heating the vacuum vessel 11 and the discharge tube 14 (not shown). It is kept above 100 ° C. This is to prevent a thin film generated on the surface of the sample 18 from being formed on the wall of the vacuum vessel 11 or the discharge tube 14 by the present process. The sample stage 12 is provided with a means for mechanically fixing the substrate 18 to be processed and a temperature
Means are provided to keep it constant between 10 ° C and + 200 ° C. A microwave having a frequency of 2.45 GHz is applied to the discharge tube 14 via the waveguide 19, and an electrodeless discharge is generated therein to decompose the gas introduced from the gas inlet 13a. Also, window 1
An electron gun can be attached instead of 7 to irradiate the sample surface with an electron beam.

Next, the etching of the silicon oxide film of the third embodiment of the present invention using the apparatus shown in FIG. 1 will be described.
FIG. 2 shows a sample 18 in which a silicon oxide film was formed on a silicon substrate when a mixed gas of NF ₃ gas and NH ₃ gas was introduced as a gas containing a halogen element and a basic gas through an inlet 13a, respectively. The etching rate of the silicon substrate and the silicon oxide film was examined by changing the mixing ratio of NF ₃ gas and NH ₃ gas. Here, the pressure in the vacuum vessel 11 is kept constant (0.3 Torr), and the partial pressure of the NF ₃ gas and the NH ₃ gas is changed. The temperature of the sample is about 25 ° C and the processing time is 10
Minutes.

From this figure, when the added amount of NH ₃ gas is small, that is, when the partial pressure ratio is 1 or less, both silicon and silicon oxide are etched, and the etching rate gradually decreases as the added amount increases. If the partial pressure of NH ₃ becomes larger than that of NF ₃ by further increasing the addition amount, a thin film will be formed on the surface of the sample 18. This thin film, as shown in FIG.
The thickness increases as the partial pressure of NH ₃ increases. Sample 18
Can be easily sublimated and removed by heating to about 100 ° C. or higher, which is higher than the temperature at which the following thin film sublimates. When the partial pressure ratio is 1 or more, silicon is not etched at all. On the other hand, the etching rate of silicon oxide increases as the partial pressure ratio of NH ₃ increases. Etching can be performed on other materials such as silicon with high selectivity. Even when the partial pressure of NH ₃ was high, no thin film was formed when the sample was kept at 100 ° C. or higher.

The thin film can be dissolved and removed by water or an organic solvent in addition to the heating as described above. Also,
The components of the thin film consisted of F and N elements by XPS
The analysis revealed that NH ₄ + and SiF ₆ -were contained, and a compound consisting of a gas containing a halogen element and a basic gas, or a compound containing a component of a substrate to be processed in these compounds was used.
It was found that NH ₄ F or (NH ₄ ) ₂ SiF ₆ was a constituent. This NH ₄ F is considered to be generated by the reaction of NH ₃ with F atoms generated by the discharge decomposition of NF ₃ to form HF, and this HF is combined with NH ₃ . Further, the etching mechanism is presumed as follows.

The charge distribution of NH ₄ F molecules is not uniform, F atoms having high electronegativity have negative charges, and NH ₄ has a positive electrode. Similarly, since O atoms have higher electronegativity than Si atoms, in SiO ₂ , O has a negative charge and Si has a positive electrode. Therefore, when NH ₄ F approaches SiO ₂ , F becomes Si due to clonal force,
NH ₄ is attracted to O, NH ₄ F dissociates and reacts with SiO ₂ ,
iF ₄ and H ₂ O. H ₂ O is desorbed into the gas phase, while SiF ₄ is NH ₉
F is combined with F to form (NH ₄ ) ₂ SiF ₆ and incorporated into the thin film.
When heated, (NH ₄ ) ₂ SiF ₆ decomposes to volatile SiF ₄ , NH ₃ , H
Removed as F. The overall reaction equation is as follows: F + NH ₃ → HF + NH ₂ HF + NH ₃ → NH ₄ F 6NH ₄ F + SiO ₂ → (NH ₄ ) ₂ SiF ₆ + 2H ₂ O (NH ₄ ) ₂ SiF → NH ₃ + HF + SiF ₄ metal Oxides can also be removed based on a mechanism similar to that described above.

For example, the following reaction is caused by a compound such as NH ₄ Cl, which is a compound of a gas containing a halogen element of alumina (Al ₂ l ₃ ) and a basic gas, and is etched.

Al ₃ O ₄ + 8NH ₄ as a gas containing a halogen element in _{Cl → 2NH 4 AlCl 4 + 3H} 2 O ↑ + 6NH 3 → NH 4 AlCl 4 → AlCl 3 ↑ + NH 3 ↑ + HCl ↑ above example, NF ₃
Although fluorine atoms were generated by the discharge decomposition of the gas and reacted with NH ₃ as a basic gas, a combination of a gas containing another halogen element and a basic gas may be used, and means other than discharge, such as light irradiation, heating, Irradiation with a charged particle beam, reaction with a highly aggressive species, or the like may be used. Activating a gas containing a halogen element and reacting it with a chlorinated gas as an active species containing the generated halogen element, or reacting a gas or a basic gas that spontaneously dissociates to produce an active species containing a halogen element Alternatively, even if a basic gas such as an NH ₃ gas is activated and reacted with a gas containing a halogen element, a silicon oxide film, a metal oxide, and the like can be removed. In addition, even if it is not necessary to cause a gas-phase reaction in the vacuum vessel to generate the gas, a halogen salt gas or, for example, a mixed gas of H ₂ O of a salt vapor or a vapor of a halogen salt aqueous solution is introduced into the vessel, The etching and removal of silicon and metal oxides can be performed in exactly the same manner.

Further, the thin film is formed thicker as the processing time is increased, but the amount of etching of SiO ₂ does not increase in proportion to the processing time as shown in FIG. That is, as shown in FIG. 15, as the processing time becomes longer, the etching amount gradually becomes saturated, and the etching rate decreases. It is considered that this is because when the thin film becomes thick, it becomes difficult to remove the etching product and the etching is suppressed. Therefore, efficient etching is possible by simply repeating the formation and removal of the thin film, instead of simply increasing the processing time. In fact, as shown in FIG. 16, using the apparatus of FIG.
Forming a thin film of sample (0.5 Torr, a mixed gas (NH ₃ remains NF ₃ gas and NH ₃ were kept at room temperature of the sample, the NH ₃ 0.25 Torr) discharged 10 min handling) and removal of the thin film (in a vacuum Heat to 120 ° C)
Were alternately performed, the silicon oxide was etched in proportion to the number of treatments.

As another means for improving the etching efficiency, a method of forming a thin film, reacting a gas containing a fluorine element with a gas containing a hydrogen element, and flowing the generated gas into a vacuum vessel is considered. For example discharge the NH ₃ into and MF ₃ 5 times the added gas mixture, was treated to form a thin film 10 minutes, SiO ₂
Was etched about 300 mm. After the above processing contrast, was treated to discharge 10 times gas added into H ₂ and NF ₃ without removing the thin film 5 min, SiO ₂ was about 600Å etching. This is due to the HF generated by the discharge of NF ₃ / H ₂ gas.
It is considered that the gas etched the silicon oxide through the thin film. On the other hand, if the NF ₃ / H ₂ gas is discharged unless a thin film is formed in advance, etching does not occur. Therefore, it is considered that the thin film has a function of increasing the concentration of HF on the surface and increasing the reactivity.

As described above, silicon oxide or metal oxide can be etched or directional etched only in a specific region by forming a thin film in a specific region or a specific direction or by forming and removing a thin film. For example, a sample having a silicon oxide film 81 formed on the surface as shown in FIG. 17 (a) is placed on a sample table 12 in a vacuum vessel 11 shown in FIG. Keep the NF ₃ / NH ₃ gas ([N
F ₃ ] / [NH ₃ ] = 1/5) is introduced from the gas inlet 13 b into the vacuum vessel 11 without discharge decomposition, and at the same time, only a specific region of the sample 18 is irradiated with ArF laser light (wavelength 193 nm). Then, the 17th
As shown in FIG. 2B, the silicon oxide film 81 is vertically etched only in the region irradiated with the laser light 82. The reason that etching occurs only in the region irradiated with the laser light 82 is that in the region, F atoms are generated by photolysis of NH ₄ gas, and the F atoms react with NH ₃ to form a halogen salt of an etching species. That's why. The vertical etching is due to the fact that the sample temperature is kept at 10 ° C,
Only the formation of 83 occurs and only a small amount of silicon oxide is etched, whereas a thin film is formed on the bottom surface irradiated with light and at the same time a part of the thin film is removed by light irradiation. This is considered to be caused by the fact that the etching proceeds efficiently.

Further, by irradiating a specific region of the substrate with light, a charged particle beam, or a neutral particle beam so as to excite the surface of the substrate to be processed, an oxide film other than the specific region can be removed.

Further, many of the basic gases have corrosiveness, toxicity, explosiveness and the like. Therefore, in the present invention, it is not always necessary to introduce the basic gas itself from the outside into the container, and a gas containing a component element of the basic gas is supplied into the container.
Alternatively, it may be formed by activating and reacting in another region. For example, if it is NH ₃ gas, relatively safe N ₂ ,
It can also be formed by using H ₂ gas and discharging a mixed gas of both.

Moreover, such degradation tends halide to gasification as NH ₄ F, for example a mixed gas of NH ₃ and HF condensed by adiabatic expansion and the like, may be supplied to the sample to form a NH ₄ F clusters .

Second Embodiment Next, an embodiment according to the second and third inventions of the present application will be described.

FIG. 3 is a schematic view for explaining an apparatus according to an embodiment of the present invention. This apparatus is a surface treatment apparatus provided with a means for etching or removing an oxide film as pretreatment in an oxidation apparatus used for manufacturing a semiconductor device. In the figure, reference numeral 300 denotes a reaction chamber which is a processing chamber for performing an oxidation process on a silicon wafer as a substrate to be processed.
A large number of substrates 301 to be processed are vertically placed or placed on a sample holder 302 in the 300. The R / F coil is provided with a heater 303 outside the reaction vessel 300 as means for heating the substrate 301 to be processed. Further, there is a gas inlet 304 for introducing a process gas for performing processing such as oxidation, diffusion, crystal growth, etc. in the reaction vessel 300, and a gas for evacuating and evacuating the gas in the reaction vessel 300. An exhaust port 305 is provided. Further, a quartz discharge tube 306 is connected to the reaction vessel 300, and the discharge tube 30
6 is coupled with a microwave waveguide 307, and a microwave power source 308
A discharge can be generated in the discharge tube 306 by the microwave from the discharge tube. From the other end of the quartz discharge tube 306, a gas for etching or removing the oxide film of the substrate 301 is introduced into the gas inlet 309,
Further, a basic gas is provided from the gas inlet 310 of the reaction vessel. Here, the basic gas introduced from the gas inlet 310 is supplied to the entire substrate 301 to be treated,
The gas is dispersed by a gas disperser 311 having a large number of openings so as to cause a uniform reaction, and is introduced into the reaction vessel 300.
Reference numeral 311 denotes a valve for separating the reaction vessel and the discharge section.

Substrate to be processed using the apparatus according to the second embodiment of the present invention.
A method for oxidizing a 301 silicon single crystal substrate according to the third embodiment of the present invention will be described. First, a vacuum is drawn into the reaction vessel 300, and NF ₃ gas and NH ₃ gas are introduced from the gas inlet 309 so that the flow rates thereof become 30 sccm and 200 sccm, respectively, and the pressure in the reaction vessel 300 is maintained at 0.5 Torr. . In this case, a silicon single crystal substrate is provided in the reaction vessel 300, and a tens of thousands of native oxide film is formed on the surface thereof. here
By performing microwave discharge on NF ₃ and NF ₃ gas for 10 minutes, the natural oxide film on the base is completely removed.
Here, a thin film is formed on the substrate to be processed 300, and the thin film is removed by a subsequent heat treatment. This step was performed while the substrate to be processed was kept at room temperature. Next, close the valve 311 to stop supplying NF ₃ and NH ₃ gas, and
While flowing an inert gas such as Ar from 304, the inside of the reaction vessel is returned to atmospheric pressure with the inert gas so as to prevent oxygen, water, or the like that causes a natural oxide film from entering the reaction vessel 300. Next, the temperature of the substrate 301 is increased to 1000 ° C. At this time, the thin film on the substrate to be processed 300 is removed, and the clean surface of silicon is exposed. In this state, the gas introduced from the gas introduction port 304 is changed from Ar to an oxidizing gas such as O ₂ + H ₂ O, O ₂ + HCl, thereby oxidizing the surface of the silicon substrate with the usual method.

The silicon oxide film formed on the silicon substrate by the above method does not incorporate a natural oxide film as in the case of the thermal oxidation of the third embodiment described later, so that the silicon oxide film has extremely high quality and characteristics such as withstand voltage and leak current. However, as compared with the case where the surface is not oxidized without performing the surface treatment, it is significantly improved.

In the above embodiment, NF ₃ and NH ₃ were simultaneously discharged as a gas for removing a natural oxide film and introduced into the reaction vessel 300.However, only NF ₃ gas was discharged, and NH ₃ was supplied from the gas inlet 310 to the gas disperser 311. May be dispersed and introduced.

As still another modification, the gas inlet 310 and the discharge tube 306
If the radicals activated by the discharge are supplied to the entire substrate 301 to be processed, the natural oxide film can be more uniformly removed.

Further, the apparatus of the embodiment can perform not only oxidation but also processing such as crystal growth and diffusion of silicon by selecting a gas, and a natural oxide film can be removed by a similar method as a pretreatment of the processing.

In this embodiment, the microwave discharge is used to excite the gas. However, other methods such as thermal, charged particle beam, reaction with an inert gas radical, and photoexcitation may be used.

Further, as in the first embodiment, the gas for removing the natural oxide film may be a combination of a gas containing another halogen element and a basic gas.

Third Embodiment Next, an example in which thermal oxidation of silicon is performed using another embodiment of the surface treatment apparatus according to the second invention of the present application will be described.

FIG. 4 is a schematic configuration diagram of an oxidizing apparatus used in this embodiment. This apparatus includes a pre-processing chamber 400 and a main processing chamber 401 for performing thermal oxidation. Pretreatment room 400 and main treatment room 40
1 is partitioned by a gate valve 402, and can be evacuated independently of each other. The main processing chamber 41 can also deposit a silicon oxide film containing an impurity element.

A quartz discharge tube 400 is attached to the pretreatment chamber 400, and the microwave introduced from a gas inlet 406 is activated by applying a microwave from a microwave power supply 404 via a waveguide 405. The generated radicals can be transported into the pretreatment chamber 400. Further, a gas inlet 407 is separately attached to the pretreatment chamber 400 so that raw gas can be introduced. The gas introduced into the room is exhausted from the gas exhaust port 408.

The substrate to be processed 409 is placed on a quartz boat 410 in the pre-processing chamber 400, and is exposed to the atmosphere between the pre-processing chamber 400 and the main processing chamber 401 by the transfer mechanism 411 through the gate valve 402. It is possible to go back and forth without.

Further, the main processing chamber 401 is provided with a gas inlet 412, a gas outlet 413, and a heater 414.

Next, an example in which the thermal oxidation of silicon according to the method of the third embodiment of the present invention is performed using the apparatus shown in FIG. 4 will be described with reference to the sectional view of FIG. First, as a substrate to be processed 409, silicon (100) of a P type doped with boron and having a resistivity of 10Ω / cm.
Using the wafer 50, organic matter contamination and heavy metal contamination were removed in advance by acid treatment or alkali treatment, and a natural oxide film was removed by dilute hydrofluoric acid treatment. However, since the substrate to be processed is usually washed with water or exposed to the atmosphere, there is a natural oxide film 51 of about 10 ° on the surface of the substrate (FIG. 5 (a)). The substrate to be processed was placed on the boat 410 in the pretreatment chamber 400 and evacuated. Next, gas inlet 406
10 sccm of NF ₃ gas, and 100 sccm of NH ₃ gas from 407,
The discharge tube 403 was discharged. Here, a thin film 52 was formed on the surface of the substrate to be processed (FIG. 5B). After the supply of gas was stopped and the pretreatment chamber 400 was evacuated, the gate valve 402 was opened, and the substrate to be treated 409 was transferred to the main treatment chamber 401.

Ar gas is flowed into the main processing chamber 401 as an atmospheric gas, and the temperature at the center of the chamber is maintained at 800 ° C. As the substrate to be processed 409 is inserted, the thin film 52 on the surface of the substrate sublimates as the substrate temperature rises, and is removed together with the natural oxide film on the surface while being transported to the center of the main processing chamber over 30 minutes. A clean silicon surface was obtained (FIG. 5 (c)).

Next, the Ar gas was switched to oxygen gas and held for 60 minutes to form a silicon oxide film 53 of about 50 ° on the surface (FIG. 5 (d)). Further, in order to evaluate the characteristics of the silicon oxide film 53, a phosphorus-doped polycrystalline silicon film 54 was deposited and patterned to fabricate a MOS capacitor (fifth embodiment).
Figure (d).

The result of examining the dielectric strength of the obtained oxide film using this MOS capacitor will be described. Figure 6 shows the area 10
FIG. 4 is a characteristic diagram showing a relationship between an applied electric field and a frequency of dielectric breakdown for a capacitor of mm ² . Here, the point in time when a current of 10 ⁻⁶ A flows per cm ² is regarded as dielectric breakdown. In the sample A on which an oxide film is formed after only performing a conventional wet treatment of diluted hydrofluoric acid or the like, about 1/4 of the whole is destroyed by a relatively low electric field of 1 MV / cm ² or less. On the other hand, in Sample B in which an oxide film is formed after performing the above-described processing, the frequency of destruction of a low electric field is only about 3%.

From this result, it was found that the uniformity of the oxide film was improved by forming the oxide film after the natural oxide film was removed by the apparatus according to the embodiment of the present invention, and the defects causing dielectric breakdown in a low electric field were reduced. I understand.

Also when focusing on the high field region above 10 MV, whereas the maximum breakdown voltage in the case of the wet process is 14 MV / cm ^2, when the present process was done with 15 MV / cm ^2, the improvement of 1 MV / cm ² breakdown voltage Be looked at. This result indicates that the quality of the oxide film is also improved, which is attributable not only to the removal of the native oxide film but also to the reduction in metal contamination.

In fact, by performing the processing of the above embodiment, Na, K, Fe,
Alkali metal and heavy metal contamination such as Cu is about 50% to about 10%
Was confirmed to have decreased. This indicates that when the natural oxide film is removed, the metals and heavy metals contained in the natural oxide film are simultaneously removed.

In this embodiment, an example in which a thermal oxide film is formed on single-crystal silicon has been described. However, this process is also effective when an oxide film is formed on the surface of another metal or semiconductor. In particular, in the case of polycrystalline silicon doped with impurities such as phosphorus which is important as a constituent material of the LSI together with single-crystal silicon, the thickness of the natural oxide film is as large as 20 to 30 mm. Therefore, the effect of the treatment of the present invention is more remarkable than single crystal silicon.

In this embodiment, the metal contamination on the silicon surface is removed together with the natural oxide film. However, if the silicon surface is sacrificed once or a gas such as basic (CH ₃ ) ₂ NH stronger than NH ₃ is used, Metal contamination existing inside silicon can also occur,
The film quality can be further improved.

Fourth Embodiment Next, an example in which impurity diffusion, which is a method according to the third embodiment of the present invention, is performed using the apparatus shown in FIG. 4 will be described. The substrate to be used is the same as that in the example in which the above-described oxidation was performed.
The sample was placed on a boat 410 of No. 0 and subjected to the same treatment using NF ₃ gas and NH ₃ gas.

Next, after evacuating the pretreatment chamber 400, the gate valve 402 was opened, and the substrate to be treated 409 was introduced into the main treatment chamber 401 by the transfer mechanism 411. At this time, the main processing chamber 401 was heated by the heater 414 and kept at 700 ° C., and the thin film formed on the surface of the substrate to be processed 409 was sublimated and removed. At this time, no natural oxide film was formed on the substrate surface.

Next, the transfer mechanism 411 is pulled out of the main processing chamber, and the gate valve 4
After closing 02, tetraethoxysilane (Si (OCH ₂ CH ₃ ) ₄ 50sccm, triethoxyarsine (As
(OCH ₂ CH ₃ ) ₃ ) 5 sccm was introduced, the pressure was set to 1 Torr, and the mixture was held for 30 minutes. As a result, as shown in the cross-sectional view of FIG. 7A, a silicon oxide film 71 containing As was deposited on the surface of the substrate 70 by about 2000.degree. Then, instead of the above gas, N ₂
Gas is introduced and the substrate to be treated 70 is heated to about 1000 ° C.
Hold for minutes. As a result of this treatment, As was diffused uniformly in the silicon substrate, and an n-type conductive impurity region 72 having a depth of 0.15 μm was formed on the surface thereof.

As a comparative example, FIG. 7 shows a cross-sectional view in the case where diffusion is performed without removing the natural oxide film as in the above-described embodiment. As can be seen from this figure, since the natural oxide film 73 is formed on the base 70, diffusion from the silicon oxide film 71 containing As is inhibited by the natural oxide film 73 serving as a barrier, or Are segregated. Therefore, unlike the above-described embodiment of the present invention, the n-type conductive region 72a has a low concentration and a non-uniform distribution.

FIG. 8 shows a histogram of the resistivity of the impurity region formed by the pretreatment method of the embodiment of the present invention and the conventional wet treatment only. From this figure, according to the embodiment of the present invention, even under the same conditions, an impurity region having a lower resistance than that of the conventional method can be obtained, and a uniform impurity region having a small variation in resistivity can be obtained. That is, since a favorable impurity region can be formed without being affected by the natural oxide film on the surface of the substrate to be processed, the characteristics of the element can be improved.

In this example, As was used as an impurity.
By using phosphine or diborane instead of (OCH ₂ CH ₃ ) ₃ , a diffusion layer containing phosphorus or boron as an impurity can be formed. The present invention can be applied to addition of various other impurities.

In the above-described embodiment, an example in which an oxide film containing impurities is diffused into silicon as a diffusion source on silicon is described. However, the present invention is also effective in a case where diffusion is directly performed from a gaseous phase such as diborane to the surface of a semiconductor substrate. It is.

After diffusing impurities from the oxide film formed as a diffusion source by heat treatment, the impurity is again transferred to the pretreatment chamber 400 in FIG. 4, and a gas containing a halogen element and a basic gas such as NH ₃ are supplied to the oxide film. Can also be removed. This allows efficient processing of the substrate to be processed.

Fifth Embodiment FIG. 9 is a schematic diagram of still another dry process surface treatment apparatus according to a second embodiment of the present invention for performing etching by using discharge.

In the figure, reference numeral 900 denotes a reaction vessel (chamber).
Reference numeral 00 includes a discharge chamber 901 for generating discharge and a processing chamber 902 for performing processing. Reference numeral 912 denotes a waveguide that supplies microwaves for generating a discharge into the discharge chamber 901;
Reference numeral denotes a coil for generating a magnetic field in the discharge chamber 901 to control the discharge in the discharge chamber 901. An ECR discharge can be generated by the microwave and the magnetic field. Reference numeral 904 denotes a gas inlet for sending a process gas for performing an etching process into the discharge 901.
In the processing chamber 902, the substrate to be processed 905 is placed on the sample stage 906.
Installed on top. Further, a gas introduction pipe 907 having a plurality of openings for uniformly supplying a gas for performing a surface treatment for removing an oxide film to the surface of the substrate to be treated in the treatment chamber 902.
The gas introduction tube 907 is a quartz discharge tube 9
Connected to 08. Further, the discharge tube 908 is connected to a microwave waveguide 909, and a discharge is generated in the discharge tube 908 by supplying a microwave from a microwave power supply 910. Further, a gas for removing an oxide film can be introduced from a gas introduction port 911 at the other end of the quartz discharge tube 908.

Further, the processing chamber 902 can be evacuated from the gas exhaust port 913. Further, a heater 914 is provided around the discharge wall made of quartz and the gas introduction tube of the reaction vessel 900 so that heating can be performed. Although not shown, the sample stage 906 is provided with heating and cooling means so that the substrate to be processed 905 can be heated and cooled.

Using the apparatus according to the second embodiment of the present invention, the natural oxide film formed on the surface of the substrate to be processed is favorably removed before the dry etching is performed, or the surface of the substrate to be processed is removed after the dry etching. Deposits and contaminants composed of oxides can be satisfactorily removed.

When the native oxide film on the surface of the substrate to be processed is removed as a pre-dry etching process using the apparatus of this embodiment, the improvement in terms of the reduction of the dead time until the underlying substrate material is etched and the reduction of the etching residue are improved. Can be achieved. Further, if the substrate to be processed is processed by a gas containing a halogen element and a basic gas as a post-process after the etching,
Substances adhering to the surface during etching, such as contaminants from the mask material and components of the reaction vessel, or contamination from the gas, can be removed to obtain a clean substrate surface.

In this embodiment, the case where etching is performed by the apparatus shown in FIG. 9 has been described. However, when a deposition gas is supplied from the gas inlet 904, an oxide film is deposited on the substrate 905 to form a thin film such as a metal film. It is also possible to apply to other processing such as plasma CVD.

If the natural oxide film is removed in the same manner as in the above embodiment before performing the plasma CVD, there is an advantage that the adhesion between the substrate to be processed and the thin film is improved.

Sixth Embodiment Next, as another embodiment of the second invention of the present application, an example of a surface treatment apparatus for performing epitaxial growth will be described.

FIG. 10 is a schematic diagram of an apparatus according to an embodiment of the present invention. This apparatus mainly includes a pretreatment chamber 100, a transfer chamber 101, and a reaction chamber 10
2 and a spare room 103. It comprises a pretreatment chamber 100, a transfer chamber 101, a reaction chamber 102, and a preliminary chamber 103. The pretreatment chamber 100 has a gas inlet 104 for introducing a reaction gas, a gas exhaust port 105 for exhausting gas, and a sample table 10 for mounting a sample.
6. A window 118 for irradiating light and a heater 107 for heating the wall of the pretreatment chamber are provided. Here, the sample stage 106 is provided with a mechanism for electrostatically bringing the sample of the substrate to be processed into contact with the sample stage and a cooling mechanism so that the sample can be cooled to -100 ° C. An exhaust gas treatment device 108 is attached to the gas exhaust port 105.

The transfer chamber 101 has two gas exhaust ports 109 and a sample stage 110.
A heater 111 is embedded in the sample stage 110 so that the sample can be heated up to + 300 ° C. The reaction chamber 102 has a gas inlet 112 and a gas outlet.
113 is provided, and around the reaction chamber 102, a coil 114 for applying high-frequency heating to the sample in the chamber is wound,
The coil is connected to a high frequency power supply.

The spare chamber 103 has a gas exhaust port 1 to evacuate the chamber.
15 and a gas inlet 116 for introducing a rare gas such as N ₂ gas to return the inside of the chamber to atmospheric pressure. In addition, the apparatus as a whole is a load lock type, and each room 100, 101, 102, 103
Is separated by gate valves 117a, 117b and 117c, and has a mechanism capable of transporting a sample between chambers.

Next, an embodiment of the third invention of the present application in the case of performing epitaxial growth using this apparatus will be described. First,
A silicon substrate as a substrate to be processed was washed with an acid solution or an alkaline solution to remove organic contamination and metal contamination, and then treated with diluted hydrofluoric acid to remove a natural oxide film. Next, the silicon substrate is put into the preliminary chamber 103 and evacuated, and then the gate valve 1
17a is opened and transported into the pretreatment chamber 100.
I keep it. Here, a natural oxide film of about 10 ° is formed on the surface of the substrate before the silicon substrate is put in the preliminary chamber and evacuated. Next, NF ₃ gas 0.5 Tor
r, 0.25 Torr of NH ₃ gas is introduced, and A
r Irradiated with laser light (wavelength 193 nm). When this treatment was performed for 10 minutes, a thin film was formed on the substrate. Next, the gate valve 117b is opened, and the transfer chamber 101 evacuated in advance is evacuated.
The substrate was transported to the sample stage 110 and placed on the sample stage 110. This sample table 1
When the substrate was kept at 200 ° C. for 10 minutes on 10, the thin film sublimated and was removed. At this time, the natural oxide film was also removed. Next, the gate valve 117c was opened, and the substrate was transferred into the reaction chamber 102 which was evacuated. In the reaction chamber 102, the substrate temperature is raised to 900 ° C., and the SiH ₂
Was held by introducing C ₁₂ 20 minutes, epitaxial layer having a thickness of about 10 microns on a silicon substrate was formed. This epitaxial layer had a uniform thickness and specific resistance, and no crystal irregularity was observed. On the other hand, when the natural oxide film was not removed in the pretreatment chamber 100, small protrusions were found on the surface of the grown epi layer, and crystal defects occurred at the interface between the epi layer and the substrate. As described above, by using the apparatus according to the embodiment of the present invention, an epitaxial layer having high film quality could be formed.

FIG. 11 shows an example of another surface treatment apparatus for performing epitaxial growth. This device is a barrel-type reaction vessel 20
A susceptor 202 for placing the substrate 201 in 0 is arranged. In order to heat the substrate 201 by high frequency, the reaction vessel 2
A coil 203 is wound around 00 and connected to a high frequency power supply. The reaction gas is introduced from gas introduction pipes 204 and 205 connected to the reaction vessel 200. On the other hand, a discharge tube 206 made of quartz is attached to the reaction vessel 200,
A microwave of 2.45 GHz generated from a microwave power supply 208 via an applicator 207 is applied to 6.

Next, a process which is an embodiment of the third invention of the present application using the apparatus of this embodiment will be described. First, the silicon substrate 201 is placed on the susceptor 202 in the reaction vessel 200,
The inside of the container 200 is evacuated to a vacuum. Then, discharge tube 2 made of quartz
At 06, NF ₃ gas is introduced at a flow rate of 60 sccm. Next, NH ₃ gas was introduced at a flow rate of 60 sccm from the gas introduction pipe 204, and the reaction vessel was
The pressure inside 200 is kept at 0.2 Torr. Then, microwave power
Turns 208 on, causing discharge. This process is performed for 10 minutes.
As a result, a thin film was deposited on the surface of the substrate 201. afterwards,
After stopping the discharge and evacuating the gas, the substrate is heated by a high-frequency power source, the temperature is increased to 100 ° C., and the temperature is maintained for 10 minutes. By this treatment, the thin film deposited on the surface is sublimated, and the substrate 201
The native oxide on the surface is removed. Next, set the substrate temperature to 90
The temperature is raised to 0 ° C., SiH ₂ Cl ₂ is introduced, and epitaxial growth is caused on the surface of the substrate 201. After 20 minutes of epitaxial growth, an epitaxial layer was successfully formed over a thickness of 10 microns.

Seventh Embodiment FIG. 12 is a schematic view showing an embodiment of the surface treatment apparatus of the present invention for selectively growing tungsten as a thin film deposition on a substrate to be treated. The processing apparatus includes a pre-processing chamber 500 and a deposition chamber 501, and both chambers are separated by a gate valve 502. Since the whole apparatus is of a load lock type, a load chamber 505 and an unload chamber 506 are connected to the pretreatment chamber 500 and the deposition chamber 501 via gate valves 503 and 504 provided separately from the gate valve 502. I have. A heater 507 for heating the substrate is provided in the pretreatment chamber 500 and the deposition chamber 501.
Sample tables 508 and 509 in which are embedded are provided. In the pretreatment chamber 500, a quartz discharge tube 510, an applicator 511,
The waveguide 512 and the microwave power supply 513 are connected, and the long-lived radicals generated by the microwave discharge are removed from the pretreatment chamber.
It can be transported within 500. Furthermore, the discharge tube 5
A gas introduction pipe 513 for supplying gas without passing through 10 is provided. On the other hand, the deposition chamber 501 has a gas introduction pipe 5 for introducing a mixed gas of a deposition gas such as WF ₆ and H _2.
14 are provided. The deposition gas may be a mixture of WF ₆ and silane mixed with hydrogen or argon. The exhaust system includes separate exhaust devices (515) for the load chamber 505, the unload chamber 506, the pretreatment chamber 500, and the deposition chamber 501, respectively.
(516), (517), and (518) are provided.

Next, using a surface treatment apparatus for performing the thin film deposition,
An embodiment of the second invention of the present application for performing selective growth of tungsten will be described.

First, as a substrate to be processed, FIGS.
Three samples A, B, and C as shown in the cross-sectional view of (c) are prepared. Here, the sample A has a PSG film 22 having an opening 21 formed on the surface of a silicon substrate 20, and an impurity diffusion layer 23 formed on the substrate surface of the opening 21. Sample B
Is formed by forming a BPSG film 24 having an opening 21 on the surface of a silicon substrate 20, and forming a metal layer 25 such as an aluminum alloy on the substrate surface at the bottom of the opening 21. In addition, sample C
FIG. 9 is a cross-sectional view of one manufacturing step of an S transistor, in which a polycrystalline silicon gate electrode is formed on a P-type silicon substrate via a gate oxide film 27, and impurity diffusion serving as a source / drain is formed on both sides of the gate electrode 28; Layers 29a and 29b are formed. Here, 30a is a field oxide film, 30b is an insulating film, and 31a and 31b are contact holes.

The following processing is performed on such samples A, B, and C using the apparatus of the embodiment of the present invention.

First, the sample is placed in the load chamber 505, and exhaust is performed. Next, the gate valve 503 is opened, and the sample is transported to the pretreatment chamber 500. Here, after evacuation in advance to 0.1 Pa or less, NF ₃ gas is introduced into the quartz discharge tube 510 at 30 sccm, and NH ₃ gas is introduced at a flow rate of 30 sccm from the gas introduction tube 513 that does not pass through the discharge tube. The pressure is maintained at 13 Pa, and microwaves are applied to discharge. This process is performed for 5 minutes, and then the temperature of the substrate is increased by heating the heater 508 while exhausting the pretreatment chamber. After exhausting sufficiently, the gate valve 502 is opened, and the sample is transported to the deposition chamber 501. Sample table 50 in deposition chamber 501
The sample transported to above 9 is heated to 350 ° C., which is the selective growth temperature of tungsten, using heater 507. Thereafter, tungsten is deposited by introducing a deposition gas such as the above-mentioned mixed gas of WF ₆ and hydrogen. After the tungsten film was deposited, the cross section of Samples A, B, and C was observed by SEM to examine the deposition state of tungsten. The diffusion layer of Sample A, the metal layer of Sample B, the diffusion layer of Sample C, and the gate electrode Only selectively and satisfactorily tungsten was formed. For comparison, when the treatment in the pretreatment chamber was not performed, the growth of tungsten as described above was not performed.

As described above, when tungsten is grown after performing the pre-treatment of removing the natural oxide film on the surface of the substrate to be processed, tungsten can be selectively and favorably grown, and the natural oxide film is removed. The contact resistance of holes and through holes can be reduced. In fact, according to the embodiment of the present invention, the contact resistance is n ⁺ , P ⁺
When tungsten was grown on the mold silicon, a contact size of 1.0 μmφ and 10Ω and 200Ω or less, respectively, was formed.

As the gas introduced into the pretreatment chamber, a mixed gas of NF ₃ and NH ₄ may be discharged at the same time, or one of NF ₃ or NH ₄ gas is discharged, and the pretreatment is directly performed without discharging the other gas. May be introduced into the room. The N ₂ F ₄ in place of _{NF 3, XeF 2, ClF 3} , SF 6, Cx
Any gas containing a halogen element such as Fy (x = 1 or more, y = 2x + 2) may be used. Instead of NH ₃ , another basic gas such as AsH ₃ , PH ₃ , (CH ₃ ) ₂ NH, N ( CH ₃ ) ₃ , NH ₂ (CH) or the like may be used. By changing the combination of gases, the optimum condition of the gas flow pressure for performing the pretreatment slightly changes, but basically, the present invention is effective if a combination of a gas containing a halogen element and a basic gas is used. .

In addition, the deposition chamber of this embodiment was an example of a single wafer type,
Needless to say, a plurality of barrel-type containers can be processed.

Further, the thin film to be deposited is not limited to tungsten, but may be another high melting point metal such as molybdenum or tantalum, another metal, or polycrystalline silicon. For example, in the case of polycrystalline silicon, after performing a pretreatment for removing a natural oxide film as in the above embodiment, for example, the
By maintaining the temperature at 650 ° C. and introducing the SiH ₄ gas, a polycrystalline silicon film can be formed on the substrate to be processed.

By forming a polycrystalline silicon film on the substrate to be processed in this manner, even if the contact holes 31a and 31b are buried in FIG.
Since no natural oxide film is formed on the gate electrodes 29a and 29b and the gate electrode 28, conduction with these diffusion layers and the like can be extremely excellent.

Eighth Embodiment FIG. 14 shows an outline of a surface treatment apparatus according to another embodiment of the second invention of the present application for depositing a thin film. This apparatus is different from the seventh embodiment in that the chamber for performing the pretreatment and the chamber for forming the thin film are the same. In the figure, reference numeral 600 denotes a processing vessel for performing a main reaction, and
01 is electrostatically or mechanically fixed to the sample table 602 and installed. Reference numeral 603 denotes a heating unit for heating the object to be processed 601 provided below the sample table 602. The container 600 can be evacuated from two exhaust ports 604, and gas introduction ports 605a and 605b for introducing a process gas for thin film deposition similar to the seventh embodiment are connected to the processing vessel. I have.
Further, two gas supply means 606 for uniformly supplying a gas containing a halogen element such as NF ₃ and NH ₃ and a basic gas for removing and etching the oxide film to the substrate to be processed are provided in the container 600. The gas supply means 606 is connected to a quartz tube 607 provided outside the reaction vessel 600. The quartz tube 607 is connected to the microwave waveguide 608 so that a microwave is generated from the microwave power supply 609 to generate a discharge in the quartz tube 607. A gas inlet 61 into which a gas for removing and etching an oxide film is introduced is introduced into the quartz tube 607.
A further gas inlet 611 is provided so that other gases can be mixed in the downflow region of 0 and the discharge.

The same effect as that of the seventh embodiment can be obtained even with the surface treatment apparatus according to the other embodiment of the present invention.

Ninth Embodiment Next, as a method according to a third embodiment of the present invention, an example in which a contact hole is formed will be described.

FIG. 18 is a process sectional view for forming a contact hole by using the apparatus of one embodiment of the first invention shown in FIG. First, as shown in FIG. 18 (a), a silicon oxide film 91 having a thickness of 1.5 μm was formed as an insulating layer on a p-type silicon substrate 90 by a CVD method, and then a sample coated with a resist 92 was formed. Next, a resist 93 (having a diameter of 1 μm) in the contact hole portion is formed by a photolithography process.
After removal of m), mounted on a sample stage within a vacuum container shown in FIG. 1, while maintaining the sample to 25 ° C., NF ₃ gas 0.05Torr from the gas inlet 13a, the NH ₃ gas 0.45Torr After introducing and applying a microwave of 400 W to the discharge tube for 10 minutes, the process of holding the sample at 120 ° C. for 30 seconds was repeated, and the silicon oxide film 91 was etched by about 4000 °. As a result, as shown in FIG. 18 (b), the silicon oxide film 91 was isotropically etched, and the opening diameter of the silicon oxide film 91 became larger than the opening diameter of the resist mask. At this time, the silicon oxide film
No damage was found on the surface of 91.

This is because the NH ₄ F molecules of the halogen salt for etching the silicon oxide film are larger than the fluorine atoms, and therefore do not enter the inside of the silicon oxide film 91 and do not form silicon oxyfluoride.

Next, the silicon oxide film 91 is etched by about 1 μm by reactive ion etching using a mixed gas such as a CF ₄ gas and a H ₂ gas, and a groove 93 leaving a small portion of the silicon oxide film is formed.
formed a.

The silicon oxide film 91 is formed by this reactive ion etching.
Further, deposits such as silicon oxide were formed on the side walls of the resist 92.

Next, using the apparatus shown in FIG. 1 again, a thin film is formed and removed under the same conditions, and the silicon oxide film is etched.
As shown in FIG. 18 (d), the contact hole 93b was completely opened. This treatment also removed the silicon oxide attached to the side wall of the hole.

Next, after a P-type diffusion 95 is formed in the contact portion by a diffusion process using POCl ₃ gas, the resist mask 92 is removed by O ₂ plasma as shown in FIG. 18E using a barrel-type plasma device. did. Here, the contact part Si
A natural oxide film 96 was formed on the surface. This sample was placed again on the sample stage in the vacuum vessel shown in FIG. 1 and processed under the same conditions, and only the thin film 97 was formed. Next, the sample was placed on a sample stage in a sputtering apparatus, evacuated, heated, and kept at about 120 ° C. for 30 seconds. By this processing, the first
8 The thin film is removed as shown in FIG.
Had also been removed. The reason why the thin film was removed in the sputtering apparatus here is that when the sample is removed in the apparatus shown in FIG. 1, even if the native oxide film is removed at that time, the sample is exposed to the atmosphere when transporting the sample to the sputtering apparatus. Is formed again.

Next, while the sample was kept in a vacuum, an Al-Si alloy was sputtered and deposited on the sample surface. As a result, FIG. 18 (h)
As shown in the figure, the inside of the contact hole was completely filled with the Al-Si alloy.

As described above, by using the present invention, a contact hole can be formed without damaging the silicon oxide film and leaving no deposit on the side wall.
Furthermore, since the contact hole had a high aspect ratio but a wide opening, the Al alloy could be completely buried in the hole without spattering by sputtering.

Next, the contact resistance formed according to the above embodiment was measured. The result will be described with reference to FIG. The forming step C is formed according to the above embodiment. For comparison, the process up to the step shown in FIG. 18 (b) was performed, and the measurement result of a sample in which a contact hole was completely opened only by reactive ion etching and the natural oxide film of the contact portion was not removed (step A) FIG. 18 shows a measurement result (step B) of a sample in which the natural oxide film on the diffusion layer 95 was not removed in the steps shown in FIG. Here, the resistance values before and after annealing (450 ° C., 30 minutes) are also shown. The material formed in the step A has a very high contact resistance and does not become so low even when annealed. This is presumably because the contact portion was damaged by the ion bombardment. In contrast, process B
The sample formed in step 2 has a high resistance immediately after formation, but becomes extremely low due to the annealing treatment. This result indicates that the processing of the present invention used for the final etching of the
It does not damage Si. Further, the reason why the resistance is lowered by annealing is that the natural oxide film is reduced by Al. Further, in the sample formed in the step shown in FIG. 18, the contact resistance is low immediately after formation, and hardly changes even after annealing. This is because a natural oxide film is not formed in the contact portion.

As described above, by using the method according to the second embodiment of the present invention, it is possible to form a contact having a small contact area and a low resistance, and it is not necessary to anneal. Performance can be greatly improved.

Further, in this embodiment, the silicon oxide adhering to the side wall during the reactive ion etching of the silicon oxide film is removed. Deposits formed in the etching step can also be removed. For example, if Si is etched by reactive ion etching using a silicon oxide film as a mask, or if a deposition gas containing silicon is added during etching, deposits will be formed on the side walls and the back surface of the sample. Therefore, it was confirmed that it could be removed by the treatment according to the present invention.

Tenth Embodiment Next, the etching of a silicon oxide film according to an embodiment of the fourth invention of the present application using the apparatus shown in FIG. 1 will be described.
FIG. 20 is a撃合gas of SF ₆ gas and the H ₂ O gas, inlet 13a
The etching rates of the silicon substrate and the silicon oxide film of Sample 18 in which a silicon oxide film was formed on the silicon substrate when introduced from a silicon substrate were investigated by changing the mixing ratio of SF ₆ gas and H ₂ O gas. . Here, the pressure in the vacuum vessel 11 shown in FIG. 1 is maintained at a relatively high constant pressure, for example, 2 Torr, and the partial pressure of SF ₆ gas and H ₂ O gas is changed. The sample temperature is about 2
5 ° C. and treatment time is 10 minutes.

From this figure, it can be seen that silicon is etched at a partial pressure ratio of [H ₂ O] / [SF ₆ ] less than 1, but not etched at 1 or more, and that silicon oxide is etched at a high speed at a partial pressure ratio of 1 or more. . If the partial pressure ratio is further increased, the silicon etching rate will be approximately 0Å / m
In is maintained, and the etching rate of silicon oxide gradually decreases, but the selectivity of silicon oxide to silicon is maintained even at an extremely high partial pressure ratio. That is, by performing the treatment at a partial pressure ratio of 1 or more, silicon oxide can be etched with high selectivity to silicon.

FIG. 20 shows the results when the sample temperature was kept at room temperature (25 ° C.). When the sample temperature was kept at about 60 ° C. during the process, neither silicon oxide nor silicon was etched. When the surface of the silicon oxide treated at a sample temperature, room temperature, and a partial pressure ratio of 1 or more was analyzed by XPS, it was found that a layer containing the elements O, S, and F was formed. After treatment, the condensed layer was removed by heating the sample in vacuum (about 60 ° C.). After this treatment, the surface of the sample has an F
However, the lower portion can be removed by exposing to an excited hydrogen gas as described later or simultaneously irradiating light.

From these results, when the sample temperature is room temperature, O, S, F
It is considered that a condensed layer containing an element was formed and reacted directly with the silicon oxide, or the silicon oxide was etched by supplying an etching species from the condensed layer. Since the above-mentioned condensed layer containing F etches SiO ₂ and is strongly acidic, it is considered that F ⁻ ions and HF ₂ ⁻ ions contribute to the etching as in the etching of SiO ₂ with hydrofluoric acid. Can be Further, since the condensed layer contains S and O, the etching mechanism is assumed as follows.

First, SF ₄ gas is generated by discharge decomposition of SF ₆ gas, which is
Reacts with H ₂ O to generate SO ₂ gas. This SO ₂ gas is H ₂ O
Is combined with O atoms generated by the discharge decomposition of SO ₃ to form SO ₃ .
SO ₃ having a low vapor pressure is easily condensed, and after depositing on the sample surface, part of it reacts with H ₂ O to become liquid H ₂ SO ₄ .
Further, HF gas is generated by the reaction between F atoms and H ₂ O generated by the discharge decomposition of SF ₆ gas and the above-described reaction of SF ₄ + H ₂ O.

HF gas with large polarity is also H ₂ SO with large polarity
Dissolves easily in ₄ . Some of the dissolved HF is ionized to H
⁺ And F ^-, HF ₂ ^- or the like occurs, and some reacts with H ₂ SO ₄ HSO ₃ F
And H ₂ O. HSO ₃ F is also a highly polar liquid and HF
Was dissolved gas F ^- to produce the or HF _2.

In SiO ₂ , O has a negative charge and Si has a positive charge. Therefore, the H ⁺ ion is attracted to 0, and the F ⁻ and HF ₂ ⁻ ions are attracted to Si, and the Si—O bond of SiO ₂ is broken to generate SiF ₄ and H ₂ O. SiF ₄ and H ₂ O are volatile and are removed as a substrate. On the other hand, it is considered that Si having no polarity does not react with ions such as H ⁺ and F ⁻ and does not cause etching. The overall reaction is: Metal oxides can also be removed based on a mechanism similar to the above.

For example, instead of the mixed gas of SF ₆ gas and H ₂ O gas used in the above example, a mixed gas of S ₂ Cl ₂ gas or SO ₂ Cl ₂ gas or the like and H ₂ O gas is used, and H ₂ SO ₄ or HCl To produce alumina (Al
₂ O ₃ ) can be etched by the reaction of Al ₂ O ₃ + HCl → AlCl ₃ + H ₂ O. That is, the present invention is not limited to the above embodiment, and can be applied to other semiconductors and metal oxides.

Further, in the above embodiment, the SF ₆ / H ₂ O mixed gas is discharged, but after discharging only one of the gases, mixing is performed.
It may be supplied to the sample.

In the above embodiment, activation (discharge) is performed at a place different from the reaction vessel, but activation may be performed inside the reaction vessel. However, when performing selective etching, when ions or the like generated by activation irradiate the sample, the selectivity deteriorates. Therefore, the pressure in the container is set so that the ions react with another gas before reaching the sample. Need to be higher. Therefore, for example, when etching is performed by generating plasma in a container, it is better to use plasma etching with relatively high pressure. When O atoms are present during etching of the oxide film, they must be removed because they hinder the etching. However, when the pressure in the container is increased, the gas is decomposed (for example, H ₂ O → O + O).
H) and reactions (F + H ₂ O → HF + OH, 2OH → H ₂ O + O), and O atoms generated by sputtering of a vessel wall using quartz (SiO ₂ ) etc. The gas can be reacted and removed.

From this point of view, Al ₂ O ₃ , BN, etc. are more preferable than SiO _{2 for} the material of the vessel wall at the place of activation. The latter is harder to be etched and harder to emit O atoms,
In the former, for example, SiF ₄ is formed by etching with F atoms, which is etched by H ₂ O and, for example, F atoms.
This is because a reaction that also inhibits oxide film etching is likely to occur, such as generation of ₄ , which reacts with H ₂ O to generate SiO ₂ .

As means for activating the gas, means other than electric discharge, for example, light irradiation, heating, or active species such as charged particles and neutral radicals may be used for the reaction and the like. Further, if a gas that spontaneously dissociates to generate an active species containing a halogen element is used, activation of the gas is not necessarily required. For example, in the case of a combination of XeF ₂ , SO ₂ , and H ₂ O gas, a reaction similar to that of the above-described embodiment occurs only by mixing, and the silicon oxide film can be removed.

The gas is not limited to the above embodiment. In the above embodiment, SF ₆ gas is used as a gas containing a halogen element (here, F element), but as a gas containing an F element, for example, SF ₅ Cl, SOF ₂ , SO ₂ F ₂ , NF ₃ , C _x F _y , C _x F _y H _z , BF ₃ , P
F _3, or the like may be used.

The H ₂ SO ₄ in the above embodiment, SF _x and H ₂ O SO ₃ by reaction of
Generates, although formed which is reacted with HIO, SO ₃
May be generated in other ways. For example, heating SO ₃ powder,
It is also possible to use a method such as gasification or generation of a sulfur gas by heating the sulfur and oxidizing it.

Further, in the above-described embodiment, it is dissolved in HF or H ₂ SO ₄ , but it may be dissolved in another liquid. That is, H ₂ S, HCN, etc.
When a liquid containing an O, S, or C element and a hydrogen element and liquefied is an inorganic compound gas having a proton-donating property, the liquid easily interacts with the HF gas because the liquid is proton-donating. F while dissolved in ^-, HF ₂ ^- ions and the resulting silicon oxide or the like can be etched. This is an organic compound gas such as CH ₃ OH, C ₂ H ₅ OH, C ₃ H ₈ , (C
When using the ₂ H _{5) 2} O, etc. is the same. In addition, these gases can be introduced into the container as raw gas and liquefied on the surface of the sample. However, as in the above embodiment, the gas may be reacted in the reaction container to form a liquid.

Such liquids include H ₂ SO ₄ , H ₂ SO ₃ , HNO ₃ , HN
O ₂ , H ₂ CO ₃ , H ₃ PO ₄ , H ₃ BO ₃ , H ₃ AsO _{4 and the} like. These liquids can be formed by means similar to the above embodiment. That is, a gas containing an O element or a halogen element and any one of S, C, B, N, P, and As, for example, a gas such as CO ₂ , NO ₂ , POCl ₂ , and any of O, S, and C Inorganic compound containing any element and hydrogen element Single gas or mixed gas, or constituent elements are C, H
It can be formed by reacting with an organic compound gas containing only an element or an O element as a constituent element, for example, H ₂ O, CH ₃ OH, C ₂ H ₅ OH, C ₃ H ₈ or the like. The gas used here is not necessarily a raw gas, and can be generated from a mixed gas containing the constituent elements. For example, H ₂ O is H ₂ + O ₂ ,
CO ₂ can be generated by activating and reacting a gas such as CF _x + H ₂ O, O ₂ .

In order to perform the etching of the present invention, it is necessary to sufficiently increase the pressure in the reaction vessel or sufficiently lower the sample temperature in order to form a condensed layer on the sample surface.

In fact, in the above embodiment, when the pressure of the reaction vessel is reduced to 0.2 Torr, even if the [H ₂ O] / [SF ₆ ] partial pressure ratio is larger than 1, SiO ₂
Could not be selectively etched with respect to Si. Further, when the sample temperature was lowered to 5 ° C. in the above example, SiO ₂ could be selectively etched with respect to Si at a partial pressure ratio of 0.5 or more.

However, the condensation layer is not formed in the sample surface to form the equivalent of it in another place, low pressure in the reaction vessel be supplied to the sample, the SiO ₂ even at high sample temperature Si
Can be selectively etched. For example, in the apparatus shown in FIG. 1, a nozzle having a hole having a diameter of 0.1 mm is provided between the discharge tube 14 and the vacuum vessel 11 so that a pressure difference is generated between the discharge tube 14 and the reaction vessel. SF ₆ / H ₂ as in the example
Discharge tube pressure 3 Torr, reaction vessel pressure using O mixed gas
When discharged at 10 ^-6 Torr, the gas discharged from the nozzle undergoes adiabatic expansion, and clusters containing H ₂ SO ₄ and HF are formed. Can be caused.

The reason why the pressure in the reaction vessel is made sufficiently high is that if the pressure in the reaction vessel is low, fluorine atoms are transported to the sample and Si is etched, which is prevented. If the pressure is high, many times before the fluorine atoms reach the sample,
Since it collides with another gas and reacts to form a stable fluoride gas, etching of the Si does not occur.

On the other hand, if the pressure is high, the frequency of gas such as H ₂ O, SO ₃ and HF colliding with the sample surface increases, and a large amount of H ₂ SO ₄ including HF is formed on the surface and the etching rate of SiO ₂ is reduced. It is because it increases.

Further, to lower the sample temperature, since the adsorption probability of higher surface temperature is lower gas increases, H ₂ by cooling to 5 ° C.
The adsorption amount of gas such as O, SO ₃ and HF on the sample surface increases,
This is because a large amount of H ₂ SO ₄ containing is formed on the surface, and the etching rate of SiO ₆ increases. Such an effect of controlling the pressure and temperature is not limited to the above SF ₆ / H ₂ O gas, but applies to all gases included in the present invention. Further, when at least one of a gas containing a fluorine element such as SF ₂ and an H ₂ gas is excited in a region different from the inside of the reaction vessel, and those gases are supplied into the reaction vessel to etch SiO _2. It is also effective. Here, SiO ₂ is etched by fluorine atoms generated by excitation and H ₂ gas, or HF generated by a reaction between H atoms and a gas containing elemental fluorine. In other words, when the amount of HF adsorbed on the SiO ₂ surface exceeds a certain level, 3HF → H ₂ F ⁺ + H
Ions such as H ₂ F ⁺ and HF ₂ ⁻ are generated by F ^{− and the} like, and positively charged Si in SiO ₂ attracts HF ₂ ⁻ and O attracts H ₂ F ^+, and a reaction occurs ( 4HF + SiO ₂ → SiF ₄ + 2H ₂ O) Etching occurs. In order to etch SiO ₂ in this manner, it is essential to generate ions such as HF ₂ ⁻ and H ₂ F ^+, and it is necessary to adsorb a large amount of HF. Therefore, as described above, by increasing the pressure in the reaction vessel or lowering the sample temperature, the amount of HF adsorbed can be increased, and the etching rate of SiO ₂ can be increased.

In contrast, since the Si has no ionic HF ₂ ^-, H ₂ F
^{Even if +} is present, it is not etched. Also, if the amount of HF adsorbed is large, even if some fluorine atoms reach the sample,
And inhibits etching.

For the above reasons, the selectivity of selective etching of SiO ₂ with respect to Si is improved by sufficiently increasing the pressure in the container and lowering the sample temperature.

The present invention is not limited to the first to tenth embodiments described above.

For example, in the present invention, a gas containing a halogen element is NF
In addition to simple halogen gas ₃ gas, interhalogen gas or H, B, C, Si, P, As, S, Xe, any or a mixed gas thereof of a gas containing at least one element and a halogen element selected from Kr Or a mixed gas of them and oxygen gas.

Further, the basic gas is any one of ammonia, hydrazine, amine, phosphine, and arsine.
Or a mixed gas thereof, or a mixed gas thereof and H ₂ O, or a vapor of an aqueous solution thereof, and a gas which spontaneously dissociates to generate an active species containing at least a halogen element, is an interhalogen gas, Xe or A gas composed of Kr and a halogen element, for example, any of xenon fluoride gas,
Alternatively, a salt containing at least a halogen element, which is a mixed gas thereof, includes at least one of ammonia, hydrazine, amine, phosphine, and arsine and a halogen element.

The substrate to be processed is applicable not only to a silicon wafer but also to another semiconductor substrate, a metal or nitride, on which an oxide film such as a natural oxide film or a metal oxide is formed.

For example, as a silicon oxide, a natural oxide film of single crystal, polycrystal, amorphous silicon, a silicon oxide film formed by CVD, oxidation, or a halogen element, B, A
Any of s, P, N, C, and H may be included.

The metal oxide may be any of Al, Cu, W, Mo, Ti, an alloy thereof, a silicide thereof, or an oxide of a nitride thereof.

The substrate to be processed to which the present invention is applied is not limited to a semiconductor wafer or the like, but may be a vacuum vessel inner wall having an oxide film formed on its surface, a quartz tube, a vacuum vessel installation object, a gas inlet section inner wall, a gas exhaust section inner wall, or the like. It may be.

Further, when the oxide film is removed, the substrate to be processed is cooled to a low temperature of, for example, 0 ° C. or lower, so that the etching gas species, for example, NH ₄ F if a combination of NF ₃ and NH ₃ is used.
This method is particularly effective in removing a natural oxide film formed on the surface of the groove having a high aspect ratio because molecules are easily adsorbed to the substrate to be processed.

In addition, when the oxide film is removed at a temperature higher than the temperature at which a thin film such as NH ₄ F or (NH ₄ ) ₂ SiF ₆ is sublimated, the etching rate of the oxide film is reduced. desirable. For example, a gas containing fluorine and NH ₃ , NH ₄ OH, NH ₃
In the case of a mixed gas of H ₂ O and H ₂ or H ₂ , it is desirable to carry out the reaction at 100 ° C. or lower.

Further, as is clear from FIG. 2, the pressure ratio of the two gases for etching the oxide film is NH ₃ , the mixed gas of NH ₃ and H ₂ O or H ₂ , or the pressure of NF ₃ with respect to the vapor of the NH ₄ OH aqueous solution. In the case of the ratio, it is advantageous that the ratio is 1 or more in that high selective etching can be performed.

Furthermore, the thin film formed by etching the oxide film can be removed by irradiating the substrate to be treated with light or electrons or introducing active neutral particles into the reaction vessel in addition to removing the thin film by heating. . Further, by using a down-flow apparatus, by exposing to active species generated by the discharge of H ₂ gas, or simultaneously irradiating light, it is possible to remove a small amount of halogen remaining on the surface of the treated substrate.

〔The invention's effect〕

According to the present invention, a thin film such as NH ₄ F and H ₂ SO ₄ / HF, by selectively forming a condensed layer on a surface of a substrate to be processed without causing damage to an oxide such as a semiconductor or metal, or Can be removed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a surface treatment apparatus according to one embodiment of the present invention, FIG. 2 is a characteristic diagram showing the principle of the present invention, FIG.
FIGS. 9 to 12 and 14 are schematic views of a surface treatment apparatus according to another embodiment of the present invention, FIG. 5 is a cross-sectional view according to the embodiment of the present invention, and FIGS. FIG. 7 is a characteristic diagram for explaining the effect of the embodiment of the present invention, FIG. 7 is a sectional view for explaining the effect of the embodiment of the present invention, and FIG. 13 is a diagram for explaining the embodiment of the present invention. 15 to 17 are explanatory views for explaining an embodiment of the present invention, FIG. 18 is a process cross-sectional view according to an embodiment of the present invention, FIG. 19 and FIG. FIG. 6 is a characteristic diagram for explaining the effect of FIG. 11 Vacuum container, 13a, 13b Gas inlet, 14 Discharge tube, 15 Gas outlet, 18 Sample, 19 Waveguide.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-52932 (JP, A) JP-A-61-256725 (JP, A) JP-A-62-285424 (JP, A) JP-A 63-285424 53929 (JP, A) JP-A-59-11629 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 21/3065

Claims (12)

(57) [Claims] An object of the present invention is to accommodate a substrate having an oxide film formed on the surface of the substrate in a reaction vessel capable of evacuating, forming a thin film containing a halogen salt on the oxide film, and removing the oxide film. Characteristic surface treatment method. 2. The surface treatment method according to claim 1, wherein a halogen salt gas is supplied into the reaction vessel. 3. Activating at least one of a gas containing a halogen element and a basic gas in a region different from the reaction vessel,
The surface treatment method according to claim 1, wherein the gas is supplied into the reaction vessel. 4. After forming the thin film on the oxide film,
The surface treatment method according to claim 1, wherein the substrate is heated, or the substrate is irradiated with light, a charged particle beam, or a neutral particle beam. 5. The gas containing a halogen element may be a halogen simple gas, an interhalogen gas, or H, B, C, Si,
4. A gas containing at least one of P, As, S, Xe, and Kr and a gas containing a halogen element, or a mixed gas thereof, or a mixed gas of these and oxygen gas. The surface treatment method described. 6. The basic gas is one of ammonia, hydracine, amine, phosphine, and arsine.
Or a mixed gas thereof or a mixed gas thereof with H ₂ O or a surface treatment method according to claim 3, characterized in that the vapor of an aqueous solution thereof,. 7. The method according to claim 1, wherein the activation is any one of discharge, light irradiation, heating, irradiation of a charged particle beam, and reaction with an electrically neutral active species. 3. The surface treatment method according to 3. 8. The oxide film may be a natural oxide film of single crystal, polycrystal, amorphous silicon, a silicon oxide film formed by CVD or oxidation, or a halogen element, B, As, P, N, C,
The surface treatment method according to claim 1, wherein any one of H is included. 9. The oxide film is any one of Al, Cu, W, Mo, Ti, an alloy thereof, or a silicide thereof,
The surface treatment method according to claim 1, wherein the surface treatment is a metal oxide of a nitride thereof. 10. The surface treatment method according to claim 1, wherein said oxide film is removed before or after processing of said substrate by etching, deposition, oxidation, diffusion and epitaxial growth. 11. After etching a part of the oxide film of the base by a charged particle beam, the base in which the remaining oxide film is left is accommodated in the reaction vessel, and the remaining oxide film is removed. The surface treatment method according to claim 1, wherein the surface is removed. 12. A substrate to be processed having a metal or semiconductor oxide film formed on the surface of the substrate is housed in a reaction vessel, and H ₂ SO ₄ , H ₂ SO ₃ , HNO ₃ in which anions containing a halogen element are dissolved. , HNO
_2. A surface treatment method comprising forming ₂ , H ₂ CO ₃ , H ₃ PO ₄ , H ₃ BO ₃ or H ₃ AsO ₄ on the oxide film and removing the oxide film.