JP3456933B2 - Semiconductor processing apparatus cleaning method and semiconductor processing apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor processing apparatus cleaning method and a semiconductor processing apparatus, and more particularly to a semiconductor processing apparatus cleaning method and a semiconductor processing apparatus using a reactive gas having radicals.

[0002]

2. Description of the Related Art For objects requiring cleaning,
There is a manufacturing apparatus for performing a desired process on a semiconductor wafer on which an IC is formed, a liquid crystal thin film circuit, or the like.

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

Chemical Vapor Deposition Method (Chemical
In a CVD apparatus for depositing a semiconductor, an insulator, a metal film or the like on a semiconductor wafer by Vapor Deposition (hereinafter, referred to as CVD) to form a film, a film is formed on a reaction chamber other than the semiconductor wafer, an exhaust pipe, a pump, or the like. And dust adheres.

Therefore, depending on the kind of the deposits generated at the time of film formation on the semiconductor wafer and adhering to various places, ClF ₃ , NF
_3. Select a cleaning gas of HCl as appropriate and use CVD
It was introduced into the inside of the equipment to decompose and discharge the deposits, and the reaction chamber of the semiconductor processing equipment and the exhaust pipe were cleaned.

For example, in a silicon epitaxial growth apparatus, a susceptor holding a semiconductor wafer is placed at 1100 ° C.
The silicon adhering to the susceptor is cleaned by heating to a temperature of about ₂ ° C and flowing HCl with H ₂ . Further, in a film forming apparatus for polysilicon or silicon nitride,
The device is cleaned by flowing ClF ₃ directly. In addition, CF ₄ and O ₂ may be caused to flow inside the CVD apparatus to generate radicals by plasma, and cleaning may be performed.

[0007]

However, in the conventional method for cleaning a semiconductor processing apparatus as described above,
If ClF ₃ is selected as the cleaning gas,
It is very reactive and suitable for cleaning, but due to this high reactivity, careful handling was required such as selection of piping and sealant and prevention of mixing with other gases.

Further, ClF ₃ and NF ₃ are very expensive cleaning gases, and the cost of cleaning itself occupies 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 placed inside, so that the reliability of the device is improved. Was the cause of the decrease.

When cleaning is performed with a gas in which radicals are generated by plasma, plasma is generated at a low pressure, and thus radicals generated by collision with a wall are easily deactivated before being supplied to the reactor, and cleaning is performed. Is not efficient. Providing the plasma generation unit makes the device expensive and also a source of pollution.

Therefore, the present invention has been made in view of the above-mentioned conventional problems. A preliminary reaction chamber is provided in front of the reaction chamber, and an inexpensive stable gas is converted into a reactive gas in the preliminary reaction chamber to be converted into the reaction chamber. An object of the present invention is to provide a cleaning method for a semiconductor processing apparatus and a semiconductor processing apparatus which are highly efficient in cleaning, have less contamination, are safe, and are inexpensive.

[0012]

In order to achieve the above object, the present invention uses chlorine gas and fluorine gas, and converts them into reaction gas in a preliminary reaction chamber by utilizing heat or light for cleaning. It is introduced into the reaction chamber as gas.

In the semiconductor processing apparatus cleaning method according to the first aspect of the present invention, unnecessary deposits and impurities adhering to the reaction chamber for processing the semiconductor are introduced into the cleaning gas and reacted to be gasified and removed outside the reaction chamber. In the method for cleaning a semiconductor processing apparatus, the first gas containing chlorine and the second gas containing fluorine are supplied, the first gas and the second gas are reacted with each other to generate a cleaning gas, and the generated gas is generated. The cleaning gas is introduced into the reaction chamber.

According to this structure, the cleaning gas which is a reactive gas can be generated immediately before the reaction chamber, and the gas can be stably supplied. In addition, the cleaning effect is stable regardless of the type of adhered matter. Also, an expensive cleaning gas is used by reacting an inexpensive cleaning gas in the preliminary reaction chamber to generate a gas containing an active intermediate that efficiently cleans deposits, deposits, etc. in the reaction chamber. There is no need. Since chlorine gas and fluorine gas are caused to react with heat or light energy, impurities can be mixed from the preliminary reaction chamber with a small amount of pressure, and it is possible to react at a high pressure state, and by collision with the inner wall of the reaction chamber,
It is also possible to reduce the deactivation of active radicals. The pressure in the preliminary reaction chamber can be reduced from a reduced pressure of several Torr to several kgf /
It can be set within a range up to a pressure of about cm ² . Further, by adjusting the conductance valve, it is possible to set the pressure in the preliminary reaction chamber high and decrease the pressure in the reaction chamber.

Next, in the semiconductor processing apparatus of the present invention, unnecessary deposits and impurities attached to the reaction chamber for processing the semiconductor are introduced into the reaction chamber by the cleaning gas and reacted to be gasified and removed outside the reaction chamber. In a semiconductor processing apparatus for performing a desired film formation on a substrate, a preliminary reaction chamber that is connected to the reaction chamber and supplies chlorine gas and fluorine gas to convert these gases into a reactive gas; and the semiconductor chamber in the reaction chamber. And a supply means for supplying the raw material gas required for the film formation or the reactive gas.

Chlorine gas and fluorine gas are supplied 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 and use the desired cleaning gas for cleaning.

The type of film formation on the semiconductor wafer is S
i, SiN, SiO ₂ , metal film (W, Al, Cu, etc.)
Even when the CVD apparatus is equipped 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 halogen-containing gases 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
To use. The main substance (cleaning target) that adheres and deposits in the reaction chamber is, for example, silicon.

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

Cl ₂ and F ₂ after dissociation are Cl ₂ → 2Cl (1) F ₂ → 2F (2)

Cl and F produced by dissociation are Cl + F → ClF (3) Cause a reaction.

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).

The chemical reactions as shown in the above chemical formulas (1) to (5) continuously occur, and active F, Cl, ClF are activated.
Radicals are generated.

The radicals usually change to a stable gas immediately, but in Cl ₂ and F ₂ , they are stable for a long time because of repeating the chemical reactions of the chemical formulas (1) to (5). Exists in.

By reacting these radicals with the silicon deposited and deposited, a chemical reaction of Si + (F, Cl, ClF) → SiF _z Cl _4-z (6) occurs, and cleaning is performed. The range of z is 0 <z <4.

The deposits adhering to the reaction chamber are
The cleaning can be easily performed by supplying a gas containing a metal, a silicon compound such as SiN or SiO ₂ , or an impurity such as B or P containing an active intermediate.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION The configuration of an embodiment 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, and FIG. 2 is a partially cutaway view of a reaction chamber of a first embodiment of the semiconductor processing apparatus of the present invention, Figure 3
3 is a flow chart of a method for cleaning a semiconductor processing apparatus of the present invention.

First tank 1 for storing chlorine gas Cl ₂
And the second tank 2 storing the fluorine gas F ₂ are in communication with the preliminary reactor 5 via the pressure reducing valve 3a.

The gas discharged from the preliminary reactor 5 is introduced into the reaction chamber 8. A refiner 6 and a filter 7 can be provided between the preliminary reaction chamber 5 and the reaction chamber 8 as needed. Normally, 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 the 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 wall 13 is arranged around the rotary shaft 11.

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

In order to discharge the gas in the reaction chamber 8, the reaction chamber 8 is provided with 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, the 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.

A heating device 12 such as a heater is installed outside the reaction chamber 8. The outer wall of the reaction chamber 8 is provided with a through hole penetrating therethrough, and a plurality of supply pipes 25 for supplying the source gas or the cleaning gas into the reaction chamber 8 and the gas after the reaction in the reaction chamber 8 (unreacted gas An exhaust pipe 26 for exhausting (including) is inserted into the through hole.

Inside the reaction chamber 8, a plurality of semiconductor wafers 9
Are stacked at a predetermined interval and are held by the holder 10. The semiconductor wafer 9 and the holder 10 are arranged in the reaction container 27. Reaction container 27 and semiconductor wafer 9
A flow path plate 28 forming a flow path for the gas supplied to the reaction container 27 or the gas discharged therein is provided along the inner wall of the reaction container 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 so as to exhaust gas from below the container 27 between the reaction container 27 and the flow path plate 28. Has been.

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

A film forming method of the semiconductor processing apparatus having such a structure will be described.

(B) The semiconductor wafer 9 placed on and held by the holder 10 is heated by the heating device 12 to a temperature which is a desired film forming condition.

(B) The rotation movement of the rotary shaft 11 causes the semiconductor wafer 9 to rotate together with the holder 10.

(C) On the rotating semiconductor wafer 9, the raw material gas stored in the raw material gas tank 14 for the desired film formation is reacted from above the reaction chamber 8 after the valve 15 is opened. It is introduced into the chamber 9. Depending on the type of film formation, multiple source gases may be introduced. Further, the inside of the reaction chamber 8 is sucked by the pump 17 so as to have a negative pressure compared to the atmospheric pressure.

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

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

Here, when the deposition and 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, but the impurities and deposits in the reaction chamber 8 can be visually inspected, experience,
The cleaning end point may be detected and stopped by optically measuring impurities and deposits using a film thickness sensor or the like, or by inspecting the film formation state on the semiconductor wafer 9 (distribution and concentration of products). (1) Chlorine gas is introduced into the preliminary reaction chamber 5 from the first tank 1 by opening the valve 4a. (2) Fluorine gas causes the second 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 to cause a chemical reaction at a predetermined temperature and pressure. The chemical reaction is the above-described chemical formulas (1) to (5). (4) The reactive gas, ClF, containing the generated active intermediate is purified by a purifier 6 or a filter 7, which is provided as needed, to remove unnecessary products such as impurities and impurities. The gas from which impurities have been removed becomes a cleaning gas.

A purifier and a filter are usually provided.
In that case, the generated reactive gas remains as it is.
It becomes cleaning gas. (5) The cleaning gas from the preliminary reaction chamber 5 is a valve
It is introduced into the reaction chamber 8 by opening 18. (6) Supplying the cleaning gas to the reaction chamber 8
8 Silicon and silicon compounds deposited and deposited inside
Of metal, metal compound, ceramics, etc.
A reaction occurs and cleaning is started. (7) After the lapse of a predetermined time, the inside of the reaction chamber 8 is cleaned.
The film thickness is checked visually to see if
Sensors such as sensors, generated SiF_zCl _4-z
, Or by gas chromatography,
Determine whether to continue or stop the cleaning operation. It is continuation
If so, return to step (7). If stopped, step
Proceed to (8). (8) Close valves 4a and 4b, open valve 4c,
After purging the preliminary reaction chamber with nitrogen, the valve 18 was closed.
End the cleaning.

The exhaust gas exhausted from the reaction chamber 8 is directly emitted to the atmosphere if it has a component and concentration capable of being released to the atmosphere. Further, when the exhaust gas cannot be released into the atmosphere, various processes necessary for releasing into the atmosphere are performed.

When the cleaning gas is supplied to the reaction chamber 8, it is preferable that both the valve 18 and the exhaust valve 16 are 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 cleaning may be performed in a confined state.

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

Further, as compared with the conventional cleaning gas,
Since there are few restrictions on usage conditions and storage conditions, maintenance is easy, and it is highly safe and inexpensive.

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

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

During the film formation, the silicon film or powder is removed by 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 system pipe or the like that communicates from the partition wall 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 (adhesion causes an adverse effect on film formation), cleaning is performed.

Cl ₂ is used as the first gas and F ₂ is used as the _second gas.

The chemical reaction in the preliminary reaction chamber 8 is represented by the above chemical formulas (1) to (5) and the like, and Cl (radical), F
A cleaning gas containing (radicals), ClF molecules, ClF (radicals), etc. is generated.

The generated cleaning gas is supplied to the reaction chamber 8 after the impurities contained in the gas are removed by the purifier 6 and the filter 7 provided as necessary. Depending on the generation state of the cleaning gas, a plurality of purifiers and filters may be provided, or none may be provided.

The cleaning gas causes a chemical reaction of the chemical formula (6) with the silicon film or powder adhering to the inside of the reaction chamber 8 to become SiF _Z Cl _4-Z gas.

The cleaning gas after the reaction is pump 17
Is discharged to the outside of the device.

In the embodiment described above, Cl ₂ , F
By generating a cleaning gas containing Cl, F, ClF, etc. from ₂ , and performing cleaning, it is possible to efficiently clean the silicon deposited and deposited in the reaction chamber 8.

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

In each of the following embodiments, the same components as those in the first embodiment are designated by the same reference numerals, and the duplicated description will be omitted.

The 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 the third embodiment of the semiconductor processing apparatus of the present invention.

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

The temperature adjusting device 19 comprises a heater 19a as a heating source and a cooling pipe 19b as a cooling source. Cooling water can flow through the inside of 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 cleaning is performed using the heater 17a and the cooling pipe 17b in order to efficiently generate the cleaning gas. The temperature of the reaction chamber 5 is controlled and kept at a predetermined temperature.

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

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

In the second embodiment as 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 the third embodiment of the semiconductor processing apparatus of the present invention will be described with reference to FIG.

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

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

Around the preliminary reaction chamber 5 made of transparent quartz or a plurality of translucent quartz reaction tubes provided in the preliminary reaction chamber 5, ultraviolet rays having a specific wavelength are emitted. 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 It
The excited Cl ₂ and F ₂ have the same chemical formulas (1) to
The chemical reaction (5) is caused to generate a cleaning gas. The generated cleaning gas removes deposits adhering to the inside of the reaction chamber 8.

In the third embodiment as described above, the cleaning gas can be efficiently generated at low cost 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.

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

It is needless to say that the present invention is not limited to the above-described conventional embodiment, and can be variously modified and implemented without departing from the spirit of the 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 if the temperature inside the preliminary reaction chamber can be adjusted to a desired temperature, the cooling pipe and the heater may be provided in that order. .

The cooling tubes, heaters, electrodes, and ultraviolet lamps may have any number, installation positions, and installation areas as long as they can efficiently generate the cleaning gas.

Further, the cleaning gas after cleaning was discharged to the outside of the apparatus, but if the cleaning effect can be obtained even after use, it is re-introduced into the reaction chamber and recycled. You can also In the case of recycling, the post-reaction compound contained in the post-reaction cleaning gas may be appropriately removed and introduced.

Although the preliminary reaction chamber and the reaction chamber are separately provided, the preliminary reaction chamber may be provided in a part of the reaction chamber as long as a desired gas can be generated.

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

Further, the pre-reacted gas may be supplied to a plurality of reaction chambers.

[0091]

As described above, according to the present invention, by using a gas containing radicals and containing at least ClF as a cleaning gas, it is possible to easily clean deposits that were difficult to clean.

[Brief description of drawings]

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

FIG. 2 is a partial cross-sectional 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 cleaning method for 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 a semiconductor processing apparatus of the present invention.

[Explanation of symbols]

5 Preliminary reaction chamber 8 reaction chambers 9 Semiconductor wafer (semiconductor) 17 pumps (supply means) 19 Temperature control device (excitation means) 22 UV lamp (excitation means)

Front page continued (58) Fields surveyed (Int.Cl. ⁷ , DB name) C23C 16/44 H01L 21/205 H01L 21/3065

Claims (4)

(57) [Claims] 1. A cleaning method for a semiconductor processing apparatus, wherein a cleaning gas is introduced into a reaction chamber for processing a semiconductor to react and gasify it to remove it from the reaction chamber. A second gas containing a gas and fluorine is supplied, the first gas and the second gas are reacted with each other to generate a cleaning gas, and the generated cleaning gas is introduced into the reaction chamber. Method for cleaning a semiconductor processing apparatus. 2. A semiconductor process in which unnecessary deposits and impurities adhering to a reaction chamber for processing a semiconductor are introduced into a reaction gas by cleaning gas to be reacted, gasified and removed outside the reaction chamber, and a desired film is formed on the semiconductor by a source gas. In the apparatus, a preliminary reaction chamber which is connected to the reaction chamber and which supplies a chlorine gas and a fluorine gas to convert these gases into a reactive gas, a raw material gas necessary for forming the semiconductor film in the reaction chamber, Alternatively, the semiconductor processing apparatus is provided with a supply means for supplying the reactive gas. 3. The semiconductor processing apparatus according to claim 2, wherein the preliminary reaction chamber is provided with an excitation means for exciting fluorine gas and chlorine gas in the preliminary reaction chamber by heat or light. 4. A cleaning method for a semiconductor processing apparatus, wherein a cleaning gas is introduced into a reaction chamber for processing a semiconductor to react and gasify it to remove it from the reaction chamber, and a chlorine gas and a fluorine gas are used. Is introduced into the reaction chamber as a cleaning gas.