JP2001189273A - Cleaning method for semiconductor processor, and semiconductor processor thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To resolve the problem relative to a conventional cleaning method of a semiconductor processor, where the method uses expensive cleaning gases, corresponding to the kinds of sticking matters deposited in its reaction chamber as to increase the treatment cost of the method and make large its size. SOLUTION: In a cleaning method of a semiconductor processor, a first tank 1 for storing therein Cl2 and a second tank 2 for storing therein F2, are communicated with a preliminary reactor 5 via valves 3, 4. The cleaning gas produced out of Cl2 and F2 in the preliminary reactor 5 flows through a purifier 6 and a filter 7, and is introduced into a reaction chamber 8, to remove the adhering matters on it therefrom. In the reaction chamber 8, a semiconductor wafer 9 is mounted on a holder 10 and the holder 10 is supported by a rotational shaft 11. Near the holder 10, a heater 12 is provided, and the rotational shaft 11 is surrounded by a barrier plate 13. The raw-material gas for forming a desired film on the surface of the wafer 9 is stored in a raw-material gas tank 14, to be introduced into the reaction chamber 8 via a valve 15. The inside of the reaction chamber 8 communicated with a pump 17 via an exhausting valve 16, and then is communicated with the external.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for cleaning a semiconductor processing apparatus and a semiconductor processing apparatus, and more particularly to a method for cleaning a semiconductor processing apparatus using a reactive gas having radicals and a semiconductor processing apparatus.

[0002]

2. Description of the Related Art Objects requiring cleaning include:
2. Description of the Related Art There are manufacturing apparatuses that perform desired processing on a semiconductor wafer on which an IC is formed, a liquid crystal thin film circuit, and the like.

A conventional cleaning method for a semiconductor processing apparatus will be described.

[0004] Chemical vapor deposition method (Chemical
In a CVD apparatus in which a semiconductor, an insulator, a metal film, and the like are deposited on a semiconductor wafer to form a film by a vapor deposition (hereinafter, referred to as CVD), a film is formed in a reaction chamber other than the semiconductor wafer, an exhaust pipe, a pump, and the like. And powder adhere.

Therefore, ClF ₃ , NF,
_3. The cleaning gas of HCl is appropriately selected, and CVD is performed.
They are introduced into the apparatus to decompose and discharge attached substances, and clean the reaction chamber and exhaust pipes of the semiconductor processing apparatus.

For example, in a silicon epitaxial growth apparatus, a susceptor for holding a semiconductor wafer is heated at 1100 ° C.
By heating to about the temperature and flowing HCl together with H ₂ , silicon adhered to the susceptor is cleaned. In addition, in a film forming apparatus of polysilicon or silicon nitride,
The apparatus is cleaned by flowing ClF ₃ directly. In some cases, cleaning is performed by flowing CF ₄ and O ₂ into the inside of a CVD apparatus to generate radicals by plasma.

[0007]

However, in the above-described conventional method for cleaning a semiconductor processing apparatus,
When ClF ₃ is selected as the cleaning gas,
The reactivity is very high and suitable for cleaning, but due to the high reactivity, attention must be paid to handling such as selection of pipes and sealants and prevention of mixing with other gases.

Further, ClF ₃ and NF ₃ are very expensive cleaning gases, and there is a problem that the cost of cleaning itself accounts for a large part of the semiconductor wafer manufacturing cost.

Further, when a plasma source is provided in the reaction chamber for cleaning, the CVD apparatus itself becomes expensive and becomes a source of contamination for the semiconductor wafer mounted therein, thereby increasing the reliability of the device. Was causing the decline.

When cleaning is performed using a gas that generates radicals by plasma, the plasma is generated at a low pressure, so that radicals generated by collision with a wall are easily deactivated before being supplied to the reactor. Is not efficient. Providing a plasma generation unit makes the apparatus expensive and also becomes a source of contamination.

In view of the above, the present invention has been made in view of the above-mentioned conventional problems. A preliminary reaction chamber is provided in front of a reaction chamber, and an inexpensive stable gas is converted into a reactive gas in the preliminary reaction chamber to form a reaction gas in the reaction chamber. An object of the present invention is to provide a safe and inexpensive semiconductor processing apparatus cleaning method and a semiconductor processing apparatus with good cleaning efficiency, low contamination, and low contamination.

[0012]

In order to achieve the above-mentioned object, the present invention provides a cleaning method in which a chlorine gas and a fluorine gas are used and converted into a reaction gas in a pre-reaction chamber using heat or light. It is introduced into the reaction chamber as a gas.

According to a first aspect of the present invention, there is provided a method of cleaning a semiconductor processing apparatus, wherein unnecessary deposits and impurities adhering to a reaction chamber for processing semiconductors are introduced into a cleaning gas to cause a reaction and gasified to be removed outside the reaction chamber. In a cleaning method for a semiconductor processing apparatus, a first gas containing chlorine and a second gas containing fluorine are supplied, and the first gas and the second gas are reacted to generate a cleaning gas. The cleaning gas thus obtained is introduced into the reaction chamber.

According to such a configuration, the cleaning gas as a reactive gas can be generated immediately before the reaction chamber, and the gas can be supplied stably. Further, the cleaning effect is stabilized irrespective of the type of the deposit. In addition, an expensive cleaning gas is used by reacting an inexpensive cleaning gas in the pre-reaction chamber to generate a gas containing an active intermediate that efficiently cleans deposits and deposits in the reaction chamber. Eliminates the need. Since the chlorine gas and the fluorine gas are reacted by heat or light energy, the contamination of impurities from the preliminary reaction chamber is small, and the reaction can be performed under a high pressure state.
The deactivation of the active radical can be reduced. The pressure in the pre-reaction chamber is reduced from several Torr to several kgf /
The pressure can be set in a range up to a pressure of about cm ² . Further, by adjusting the conductance valve, it is also possible to set the pressure of the preliminary reaction chamber high and to lower the pressure of the reaction chamber.

Next, in the semiconductor processing apparatus of the present invention, unnecessary deposits and impurities adhering to the reaction chamber for processing semiconductors are introduced into the reaction chamber by reacting with a cleaning gas to be gasified and removed outside the reaction chamber. A preliminary processing chamber connected to the reaction chamber, supplying chlorine gas and fluorine gas to convert these gases into a reactive gas, and the semiconductor processing apparatus, And a supply means for supplying the above-mentioned reactive gas or a source gas necessary for film formation.

And supplying chlorine gas and fluorine gas to the reaction chamber.
By heating the reaction chamber or irradiating the reaction chamber with light, it is possible to excite the chlorine gas and the fluorine gas to perform a desired cleaning gas for cleaning.

The type of film formed on the semiconductor wafer is S
i, SiN or SiO ₂ , metal film (W, Al, Cu, etc.)
Even if a CVD apparatus is provided with a preliminary reaction chamber to generate and use a cleaning gas, it is possible to clean deposits deposited in the reaction chamber.

Further, chlorine gas and fluorine gas are HCl,
Similar effects can be obtained with other gases containing halogen such as HF.

Here, the chemical reaction of the cleaning method of the semiconductor processing apparatus will be described.

[0020] For example, the Cl ₂ is used as a first gas containing a Cl atom, _{F 2} as a second gas containing F atoms
Is used. The main substance (to be cleaned) attached and deposited in the reaction chamber is, for example, silicon.

In order to dissociate Cl ₂ and F ₂ , one or a combination of methods such as irradiation with ultraviolet light having a predetermined wavelength and heating is performed in the preliminary reaction chamber. This is Cl
₂ and F ₂ are non-reactive gases which are very stable at normal temperature and normal pressure, and do not cause a chemical reaction only by mixing.

Cl ₂ and F ₂ after dissociation are as follows: Cl ₂ → 2Cl (1) F ₂ → 2F (2)

The reaction between Cl and F generated by dissociation causes the following reaction: Cl + F → ClF (3)

Further, Cl generated by dissociation and the second gas F ₂ cause a reaction of Cl + F ₂ → ClF + F (4).

Further, F generated by dissociation and the first gas Cl ₂ cause a reaction of F + Cl ₂ → ClF + Cl (5).

Chemical reactions as shown in the above-mentioned chemical formulas (1) to (5) occur continuously, and active F, Cl, ClF
Is generated.

Radicals are usually immediately converted into a stable gas, but in Cl ₂ and F ₂ , the chemical reaction of chemical formulas (1) to (5) is repeated, so that the radical is stable for a long time. Exists.

These radicals react with the silicon deposited and deposited to cause a chemical reaction of Si + (F, Cl, ClF) → SiF _z Cl _4-z (6), thereby performing cleaning. The range of z is 0 <z <4.

The deposits adhering to the reaction chamber are:
Even metals, silicon compounds such as SiN and SiO ₂ , and impurities such as B and P can be easily cleaned by supplying a gas containing an active intermediate.

[0030]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram of a first embodiment of a semiconductor processing apparatus of the present invention. FIG. 2 is a partially cutaway view of a reaction chamber of the first embodiment of the semiconductor processing apparatus of the present invention. FIG.
4 is a flowchart of a method for cleaning a semiconductor processing apparatus according to the present invention.

First tank 1 for storing chlorine gas Cl ₂
When, the second tank 2 to the fluorine gas F ₂ is stored, and communicates with the pre-reactor 5 via a pressure reducing valve 3a.

The gas discharged from the pre-reactor 5 is introduced into the reaction chamber 8. Note that a purifier 6 and a filter 7 can be provided between the preliminary reaction chamber 5 and the reaction chamber 8 as necessary. Usually, the reactive gas from the preliminary reaction chamber 5 is directly introduced into the reaction chamber 8.

In the reaction chamber 8, a semiconductor wafer 9 (semiconductor) is placed on a holder 10. Holder 10 is rotating shaft 1
1 and is rotatable with the rotating shaft 11. A heating device 12 such as a heater is provided near the holder 10. A partition 13 is arranged around the rotation shaft 11.

A source gas for forming a desired film on the surface of the semiconductor wafer 9 is stored in a source gas tank 14. The raw material gas tank 14 is connected to the reaction chamber 8 via the reduced pressure 3 c and the valve 15.
It communicates with the inside.

In order to exhaust gas from the reaction chamber 8, the reaction chamber 8 is connected to a pump 17 (supply means) via an exhaust valve 16.
Is in communication with

A valve 18 is provided between the filter 7 and the reaction chamber 8.

Here, a case where the reaction chamber 8 is a batch type CVD apparatus will be described (see FIG. 2). Note that FIG.
Gas flows in the direction of the middle arrow.

Outside the reaction chamber 8, a heating device 12 such as a heater is provided. The outer wall of the reaction chamber 8 is provided with a through-hole penetrating therethrough. ) Is inserted into the through-hole.

In the reaction chamber 8, a plurality of semiconductor wafers 9
Are stacked at predetermined intervals and held by the holder 10. The semiconductor wafer 9 and the holder 10 are arranged in a reaction container 27. Reaction vessel 27 and semiconductor wafer 9
A flow path plate 28 that forms a flow path for gas supplied to or discharged from the reaction vessel 27 is provided along the inner wall of the reaction vessel 27. The supply pipe 25 supplies gas from below the container 27 between the semiconductor wafer 9 and the flow path plate 28, and the exhaust pipe 26 is provided to exhaust gas from below the container 27 between the reaction container 27 and the flow path plate 28. Have been.

Since the reactive gas reacted in the pre-reaction chamber has high reactivity, it is desirable to make the pre-reaction chamber 5 and the reaction chamber 8 close to each other to shorten the reaction gas path.

A method for forming a film in the semiconductor processing apparatus having the above-described configuration will be described.

(A) The semiconductor wafer 9 placed and held on the holder 10 is heated by the heating device 12 to a temperature at which desired film forming conditions are satisfied.

(B) The semiconductor wafer 9 is rotated together with the holder 10 by the rotation of the rotary shaft 11.

(C) The source gas for forming a desired film stored in the source gas tank 14 on the rotating semiconductor wafer 9 reacts from above the reaction chamber 8 after the valve 15 is opened. It is introduced into the chamber 9. Note that a plurality of source gases may be introduced depending on the type of film formation. Further, the inside of the reaction chamber 8 is sucked by a pump 17 so as to have a negative pressure as compared with the atmospheric pressure.

(D) After a desired film is formed on the semiconductor wafer 9, the unreacted raw material gas and the reacted gas in the reaction chamber 8 are discharged.

(E) When the film formation is completed, the semiconductor wafer 9
Is moved to the next step, and a new semiconductor wafer 9 on which no film is formed is placed and held on the holder 10. Thereafter, the process returns to step (a), and the operations of (a) to (e) are continued.

Here, when the deposition of the product in the reaction chamber 8 exceeds the allowable range, the following cleaning is performed (see FIG. 3).

The cleaning is performed for a preset time.
Impurities and deposits may be optically measured using a film thickness sensor or the like, and the end point of cleaning may be detected and stopped by inspection of the film formation state on the semiconductor wafer 9 (distribution and concentration of products). (1) Chlorine gas is introduced from the first tank 1 into the preliminary reaction chamber 5 by opening the valve 4a. (2) When the fluorine gas is opened by opening the valve 4b,
It is introduced from the tank 2 into the preliminary reaction chamber 5. (3) Chlorine gas and fluorine gas are mixed in the preliminary reaction chamber 5 and cause a chemical reaction at a predetermined temperature and pressure. The chemical reaction is the above-mentioned chemical formulas (1) to (5). (4) The reactive gas of ClF containing the generated active intermediate is removed by a purifier 6 or a filter 7 provided as necessary to remove products unnecessary for cleaning, impurities, and the like. The gas from which impurities and the like have been removed becomes a cleaning gas.

Usually, a purifier and a filter are provided.
In that case, the generated reactive gas
It becomes a cleaning gas. (5) The cleaning gas from the preliminary reaction chamber 5 is supplied to a valve
By opening 18, it is introduced into the reaction chamber 8. (6) Supplying a cleaning gas to the reaction chamber 8
8, silicon and silicon compounds adhering and depositing inside
Metals, metal compounds, ceramics, etc. with chemical formula (6)
A reaction occurs and cleaning begins. (7) After a lapse of a predetermined time, the inside of the reaction chamber 8 is cleaned by cleaning.
Visual inspection and film thickness control to determine whether the
Sensors such as sensors, generated SiF_zCl _4-z
, Or detected by gas chromatography, etc.
The continuation / stop of the cleaning operation is determined. Is a continuation
If so, return to step (7).
Proceed to (8). (8) Close the valves 4a and 4b, open the valve 4c,
After purging the preliminary reaction chamber with nitrogen, the valve 18 is closed.
Therefore, the cleaning is completed.

Exhaust gas exhausted from the reaction chamber 8 is emitted to the atmosphere as it is if it has components and concentrations that can be released to the atmosphere. If the exhaust gas cannot be released to the atmosphere, various processes necessary for releasing the gas to the atmosphere are performed.

When the cleaning gas is supplied to the reaction chamber 8, it is preferable that the valve 18 and the exhaust valve 16 are both opened so that a new cleaning gas always flows into the reaction chamber 8. After supplying a predetermined amount of gas, the valve 18 and the exhaust valve 16 may be closed, and the cleaning may be performed in a state of being closed.

In the embodiment as described above, by using ClF containing radicals as the cleaning gas,
The cleaning gas can be efficiently removed without changing the cleaning gas depending on the type of deposits deposited in the reaction chamber 8.

Further, compared with the conventional cleaning gas,
Since there are few restrictions such as use conditions and storage conditions, maintenance is easy, and safety is high and inexpensive.

Further, since the cleaning effect is good, the productivity of the semiconductor wafer on which a film is formed is improved. (Embodiment) A case where a polysilicon film is formed on a semiconductor wafer 9 will be described. The source gases are SiH ₄ and P
H ₃ and supplied to the reaction chamber 8 together with the carrier gas N ₂ . The semiconductor wafer 9 is heated and maintained at a desired film forming temperature before the introduction of the source gas and the carrier gas.

As the source gas reaches the semiconductor wafer 9, a polysilicon film is formed.

At the time of this film formation, the silicon film or powder is deposited on the holder 10, the inner wall of the reaction chamber 8, the rotating shaft 11, the heating device 12,
It adheres and accumulates in the exhaust pipe connecting the partition 13 or the reaction chamber 8 to the outside air.

When the silicon film or the silicon powder exceeds the allowable range at the time of film formation (adhering matter adversely affects the film formation), cleaning is performed.

Cl ₂ is used for the first gas, and F ₂ is used for the _second gas.

The chemical reaction in the pre-reaction chamber 8 is represented by the above-mentioned chemical formulas (1) to (5) and the like.
A cleaning gas containing (radical), ClF molecules, ClF (radical) and the like is generated.

The generated cleaning gas is supplied to a reaction chamber 8 after impurities contained in the gas are removed by a purifier 6 and a filter 7 provided as necessary. Depending on the state of generation of the cleaning gas, a plurality of purifiers and filters may or may not be provided at all.

[0062] The cleaning gas undergoes a chemical reaction of the silicon film or powder and formula that adheres to the reaction chamber 8 _(6), a gas SiF _{Z Cl 4-Z.}

The cleaning gas after the reaction is supplied to the pump 17.
Is discharged outside the apparatus.

In the embodiment described above, Cl ₂ , F
By generating a cleaning gas containing Cl, F, ClF, etc. from ₂ and performing cleaning, silicon deposited and deposited in the reaction chamber 8 can be efficiently cleaned.

Next, the configuration of a second embodiment of the semiconductor processing apparatus of the present invention will be described with reference to FIG.

In the following embodiments, the same components as those in the first embodiment are denoted by the same reference numerals, and overlapping description will be omitted.

A feature of the second embodiment is that a temperature adjusting device 19 (excitation means) is arranged around the preliminary reaction chamber 5 to improve the cleaning gas generation efficiency.

FIG. 4 is a configuration diagram of a preliminary reaction chamber of a semiconductor processing apparatus according to a third embodiment of the present invention.

A temperature control device 19 is provided so as to be thermally connected to the preliminary reaction chamber 5 or a plurality of reaction tubes made of nickel or alumina having corrosion resistance provided in the preliminary reaction chamber 5.

The temperature adjusting device 19 includes a heater 19a as a heating source and a cooling pipe 19b as a cooling source. Cooling water can flow inside the cooling pipe 19b.

The operation of the second embodiment having such a configuration will be described.

Before Cl ₂ as the first gas and F ₂ as the second gas are introduced into the preliminary reaction chamber 5, a preliminary gas is generated using the heater 17a and the cooling pipe 17b in order to efficiently generate a cleaning gas. The temperature of the reaction chamber 5 is controlled and kept at a predetermined temperature.

Here, if the temperature range for generating a cleaning gas based on Cl ₂ and F ₂ is between 150 ° C. and 350 ° C., a gas containing a desired active intermediate can be generated. Can be. The optimum temperature is about 250 degrees.

When the cleaning gas is not required (not generated), the output of the heater 17a is turned off and the cooling pipe 1 is turned off.
It is cooled by cooling water flowing through 7b and is maintained at a temperature of about room temperature.

In the second embodiment described above, the cleaning gas can be efficiently generated by adjusting the temperature in the preliminary reaction chamber 5, and the cleaning efficiency can be further improved.

Next, the configuration of a semiconductor processing apparatus according to a third embodiment of the present invention will be described with reference to FIG.

A feature of the third embodiment is that a cleaning gas is efficiently generated by irradiating the first gas and the second gas with ultraviolet rays.

FIG. 5 is a configuration diagram of a preliminary reaction chamber of a semiconductor processing apparatus according to a third embodiment of the present invention.

Ultraviolet light having a specific wavelength is provided around a transparent quartz pre-reaction chamber 5 or a plurality of translucent quartz reaction tubes provided in the pre-reaction chamber 5. UV lamp 22 (excitation means) at a position where irradiation is possible
Is provided.

The operation of the third embodiment having such a configuration will be described.

[0081] Cl ₂ and _{F 2} is an ultraviolet radiation having a predetermined wavelength capable of absorbing, by irradiating the first and gases Cl ₂ and the second gas _{F 2,} Cl ₂ and _{F 2} is excited You.
The excited Cl ₂ and F _{2 correspond} to the chemical formulas (1) to
The chemical reaction of (5) is performed to generate a cleaning gas. The generated cleaning gas removes deposits adhering to the inside of the reaction chamber 8.

In the third embodiment described above, the cleaning gas can be efficiently and inexpensively generated by using the ultraviolet lamp 22, and the cleaning effect in the reaction chamber 8 can be improved.

Next, a fourth embodiment of the present invention will be described.

The Cl ₂ gas and the F ₂ gas are supplied to the reaction chamber 8, and the holder 10 is heated to about 350 ° C.
In the vicinity of the holder 10, a gas containing an active intermediate is generated, and the inside of the reaction chamber 8 can be cleaned.

The present invention is not limited to the above-described conventional embodiment, and it goes without saying that the present invention can be implemented with various modifications without departing from the spirit of the present invention. For example, the heater and the cooling pipe are provided in the order of the heater and the cooling pipe along the gas flow direction, but may be provided in the order of the cooling pipe and the heater if the temperature in the preliminary reaction chamber can be adjusted to a desired temperature. .

The number, location, and area of the cooling pipes, heaters, electrodes, and ultraviolet lamps may be any as long as the cleaning gas can be efficiently generated.

The cleaning gas after cleaning is discharged to the outside of the apparatus. However, if a cleaning effect can be obtained even after use, the cleaning gas is introduced again into the reaction chamber and recycled. You can also. In the case of recycling, the compound after the reaction contained in the cleaning gas after the reaction may be appropriately removed and introduced.

Although the preliminary reaction chamber and the reaction chamber are separately provided, a configuration in which the preliminary reaction chamber is provided in a part of the reaction chamber, for example, may be used as long as a desired gas can be generated.

The cleaning gas may be HF, HCl, or the like.

Further, a configuration in which the gas subjected to the preliminary reaction is supplied to a plurality of reaction chambers may be employed.

[0091]

As described above, according to the present invention, deposits which have been difficult to clean can be easily cleaned by using a gas containing radicals and at least ClF as a cleaning gas.

[Brief description of the drawings]

FIG. 1 is a block diagram of a first embodiment of a semiconductor processing apparatus of the present invention.

FIG. 2 is a partially cutaway view of a reaction chamber of the first embodiment of the semiconductor processing apparatus of the present invention.

FIG. 3 is a flowchart of a method for cleaning a semiconductor processing apparatus according to the present invention.

FIG. 4 is a configuration diagram of a preliminary reaction chamber of a second embodiment of the semiconductor processing apparatus of the present invention.

FIG. 5 is a configuration diagram of a preliminary reaction chamber of a third embodiment of the semiconductor processing apparatus of the present invention.

[Explanation of symbols]

 Reference Signs List 5 preliminary reaction chamber 8 reaction chamber 9 semiconductor wafer (semiconductor) 17 pump (supply means) 19 temperature controller (excitation means) 22 ultraviolet lamp (excitation means)

Claims (4)

[Claims] A cleaning method for a semiconductor processing apparatus for introducing unnecessary cleaning substances and impurities adhering to a reaction chamber for processing a semiconductor by introducing a cleaning gas and reacting the gas to gasify and remove the gas outside the reaction chamber. Supplying a gas and a second gas containing fluorine, reacting the first gas and the second gas to generate a cleaning gas, and introducing the generated cleaning gas into the reaction chamber. Cleaning method for a semiconductor processing apparatus. 2. A semiconductor process in which unnecessary deposits and impurities adhering in a reaction chamber for processing a semiconductor are introduced into a reaction gas by introducing a cleaning gas and gasified to be removed outside the reaction chamber, and a desired film is formed on the semiconductor by a raw material gas. In the apparatus, a preliminary reaction chamber connected to the reaction chamber and supplying chlorine gas and fluorine gas to convert these gases into a reactive gas; and, in the reaction chamber, a source gas necessary for film formation of the semiconductor; Alternatively, a semiconductor processing apparatus comprising: a supply unit for supplying the reactive gas. 3. The semiconductor processing apparatus according to claim 2, wherein said preliminary reaction chamber is provided with an exciting means for exciting fluorine gas and chlorine gas in said preliminary reaction chamber by heat or light. 4. A cleaning method for a semiconductor processing apparatus for introducing unnecessary cleaning substances and impurities adhering to a reaction chamber for processing a semiconductor by introducing a cleaning gas and reacting the same to gasify and remove the gas outside the reaction chamber. Cleaning method for a semiconductor processing apparatus, wherein the cleaning gas is introduced into the reaction chamber as a cleaning gas.