JP2005302801A - Cleaning apparatus and method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily clean the inside of a processing chamber. <P>SOLUTION: An ion supply unit 21 takes out hydride ions from a minus ion source S by heating the minus ion source S and applying an electric field to the same. The ion supply unit 21 reduces by-products produced in a processing chamber 51 by supplying the hydride ions so taken out into the processing chamber 51 with the aid of carrier gas that is inactive gas. A halogen supply device 22 gasifies the by-products reduced as above by supplying halogen gas into the processing chamber 51. A gas exhaust device 52 exhausts the gasified by-products to the outside of the processing chamber 51. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an apparatus and method for removing by-products generated in a processing chamber.

In manufacturing a semiconductor device, various processes such as a film forming process and an etching process are performed in various processing chambers.
When a film formation process, an etching process, or the like is repeatedly performed, by-products such as SiN, SiO ₂ , Ti, TiN, W, and Ta ₂ O ₅ adhere to the inner wall of the processing chamber.

  By-products attached to the inner wall or the like of the processing chamber may cause generation of particles, deteriorate the reproducibility of the etching shape, or cloud the observation window provided in the processing chamber. Therefore, it is necessary to periodically clean the inside of the processing chamber to remove by-products in the processing chamber.

In order to remove by-products in the processing chamber, conventionally, plasma of NF ₃ (remote plasma) generated outside the processing chamber is used (see, for example, Patent Document 1), or ClF ₃ is contained in the processing chamber. It is introduced and heated (see, for example, Patent Document 2).
JP 2003-17416 A (summary, claim 10) JP 2002-93785 A (paragraph 0018)

However, since the plasma source for generating the remote plasma is expensive, the above-described cleaning method using the NF ₃ remote plasma has a problem that the apparatus cost is high.

In addition, ClF ₃ has a very high reactivity compared to fluorine and the like and has a high risk. Therefore, handling of the ClF ₃ is difficult, in order to perform the cleaning process by using a ClF _3, it is necessary to highly control for safety.

Moreover, the use of ClF ₃ is regulated in some countries due to its high risk. For this reason, ClF ₃ may not be used for cleaning the processing chamber.

  Accordingly, it is an object of the present invention to provide a cleaning device and a cleaning method that can easily perform cleaning in a processing chamber.

  It is another object of the present invention to provide a cleaning device and a cleaning method capable of performing cleaning inside a processing chamber at a low cost.

  In order to achieve the above object, a cleaning apparatus according to a first aspect of the present invention performs a cleaning process for removing a by-product generated in a processing chamber that performs a predetermined process on a semiconductor wafer. The hydride ions are supplied into the processing chamber to reduce the by-product generated in the processing chamber, and the by-products reduced by the ion supplying unit are reduced. A gasifying agent supplying means for supplying a gasifying agent for gasification into the processing chamber; and the by-product gasified by the gasifying agent supplying means by exhausting the gas in the processing chamber. And evacuation means for removing an object from the processing chamber.

  The ion supply means includes a source heating means for heating the negative ion source containing the hydride ions, and an electric field applied to the negative ion source heated by the source heating means, thereby containing the negative ion source. Electric field applying means for taking out the hydride ions that are taken out and supplying the hydride ions into the processing chamber.

  The electric field applying means may apply an electric field of 200 to 1500 V / cm to the negative ion source.

  The strength of the electric field is preferably 200 to 600 V / cm.

  The source heating means may heat the negative ion source to 250 to 1000 ° C.

  The heating temperature is preferably 400 to 800 ° C, more preferably 700 ° C.

  The gasifying agent supply means may supply a halogen gas or an organic acid as the gasifying agent into the processing chamber.

  A cleaning method according to a second aspect of the present invention is a cleaning method for removing a by-product generated in a processing chamber for performing a predetermined process on a semiconductor wafer, wherein hydride ions are introduced into the processing chamber. An ion supply step for reducing the by-product generated in the processing chamber by supplying the gas, and a gasifying agent for gasifying the by-product reduced in the ion supply step. A gasifying agent supplying step for supplying the gas into the processing chamber, and an exhausting step for removing the by-product gasified in the gasifying agent supplying step from the processing chamber by exhausting the gas in the processing chamber; It is characterized by providing.

  As is apparent from the above description, the present invention can easily perform the cleaning of the processing chamber and can perform the cleaning of the processing chamber at a low cost.

Next, the cleaning method according to the embodiment of the present invention will be described.
In the cleaning method according to the present embodiment, negative ions, specifically, hydride ions (H ⁻ ) and halogen gas (or organic acid) are used. By-products (SiN, SiO ₂ , Ti, TiN, W, Ta ₂ O _5, etc.) generated in the processing chamber are reduced by negative ions and become halides (or metal complexes by organic acids) by halogen gas, It is removed as a gaseous component.

  The ion source generating apparatus that generates the negative ion source that emits the negative ions can be configured from an electric furnace that can be controlled in atmosphere, for example, used in the ceramic industry.

  1 (a) and 1 (b) show the configuration of the ion source generator. FIG. 1B shows a cross section of the ion generator shown in FIG. 1A taken along the line A-A ′.

  As shown in FIG. 1, the ion source generation apparatus includes a processing vessel 11, a raw material gas supply device 12, a gas exhaust device 13, a heat insulation vessel 14, a heater 15, a heater control device 16, and a control device 17. Is composed of.

  The processing container 11 is a heat-resistant container formed from a metal having heat resistance or a ceramic having high reduction resistance. For example, the processing container 11 is a cylindrical container formed from high-purity alumina.

  In the processing container 11, a mounting table 11a made of alumina or the like for mounting the object to be processed T serving as a negative ion source is installed. In addition, the shape of the to-be-processed object T may be a disk shape as shown to Fig.2 (a), and may be petri dish shape (disk shape with an edge) as shown in FIG.2 (b). The object to be processed T is carried in and out after the lid 11b of the processing container 11 is removed.

  Further, a gas supply pipe 11 c for supplying a source gas for generating a negative ion source and a gas exhaust pipe 11 d for exhausting the gas in the processing container 11 are installed on the wall of the processing container 11. ing.

  The raw material gas supply device 12 is connected to the processing container 11 through a gas supply pipe 11 c and supplies a raw material gas (a gas containing hydrogen) necessary for generating a negative ion source into the processing container 11.

The gas exhaust device 13 includes an exhaust pump or the like, is connected to the processing container 11 via the gas exhaust pipe 11d, and exhausts the gas in the processing container 11.
The heat insulating container 14 is a container made of a heat insulating material, and a pipe-type heater 15 is installed on the inner wall thereof. The processing container 11 is accommodated in the heat insulating container 14 and heated by the heater 15.

  The heater control device 16 is connected to a heater 15 installed in the heat insulating container 14, and causes the heater 15 to generate heat by flowing a current of a predetermined magnitude through the heater 15, so that the processing container 11 stored in the heat insulating container 14. Is heated to a predetermined temperature.

  The control device 17 is composed of a microcomputer or the like and stores a program for generating a negative ion source. The control device 17 controls the operation of the entire ion source generation device according to the stored program, and generates a negative ion source.

  For example, the control device 17 controls the raw material gas supply device 12 to supply the raw material gas into the processing container 11. The control device 17 controls the gas exhaust device 13 to set the pressure in the processing container 11 to a predetermined pressure. The control device 17 controls the heater control device 16 to heat the inside of the processing container 11 to a predetermined temperature.

Next, the operation of the ion source generator will be described.
The object to be processed T is placed on the placing table 11a, the lid 11b is closed, and the inside of the processing container 11 is sealed. The object to be processed T is made of, for example, 12CaO · 7Al ₂ O ₃ .

  After the workpiece T is carried into the processing container 11, the ion source generation device performs the following operation in response to an instruction from an operator, for example. The following operation is performed under the control of the control device 17.

First, the source gas supply device 12 supplies a mixed gas of 20% hydrogen and 80% nitrogen into the processing container 11 as a source gas.
Subsequently, the gas exhaust device 13 exhausts the gas in the processing container 11 and sets the pressure in the processing container 11 to a predetermined pressure. Specifically, the gas exhaust device 13 sets the pressure in the processing container 11 to atmospheric pressure (for example, 9 × 10 ^{4 to} 11 × 10 ⁴ Pa).

  Further, the heater control device 16 causes the heater 15 to generate heat by flowing a current of a predetermined magnitude through the heater 15 and heats the inside of the processing container 11 to a predetermined temperature (about 1300 ° C.).

The control device 17 holds the above state for about 2 hours. Thereby, the to-be-processed object T becomes a negative ion source (hydrogen substitution C12A7) which discharge | releases a negative ion (hydride ion; H < ^- >).

The negative ion source generated as described above is a hydride ion (hydride ion; H ⁻ ) confined in a cage formed by polymerization of the AlO ₄ tetrahedron.

  As will be described later, the negative ions in the negative ion source are taken out by heating the negative ion source to a predetermined temperature and applying an electric field having a predetermined strength, and are used for cleaning the processing chamber.

Next, a cleaning method in the processing chamber will be described.
FIG. 3 shows a configuration of an apparatus for performing a cleaning process in the processing chamber.

  Hereinafter, a case where the cleaning process is performed using a halogen gas will be described. FIG. 3 mainly shows a configuration necessary for the cleaning process for easy understanding, and an apparatus for supplying a processing gas necessary for manufacturing the semiconductor device is omitted.

  As shown in FIG. 3, the apparatus for performing the cleaning process includes an ion supply unit 21 that supplies negative ions to the processing chamber 51, a halogen supply device 22 that supplies halogen gas to the processing chamber 51, and the processing chamber 51. And a semiconductor processing unit 23 that performs a predetermined process on the semiconductor wafer, an ion supply unit 21, a halogen supply device 22, and a control device 24 that controls the semiconductor processing unit 23.

The ion supply unit 21 includes a processing chamber 31, a high voltage power source 32, a source gas supply device 33, a gas exhaust device 34, and a carrier gas supply device 35, and takes out negative ions from the negative ion source S. This is supplied to the semiconductor processing unit 23.
The processing chamber 31 is a processing chamber formed from, for example, aluminum. On the wall of the processing chamber 31, piping for circulating various gases is installed.

  Specifically, a raw material gas supply pipe 31 a for introducing a raw material gas into the processing chamber 31, a carrier gas supply pipe 31 b for introducing a carrier gas into the processing chamber 31, and a gas in the processing chamber 31 are used. A gas exhaust pipe 31c for exhausting and an ion supply pipe 31d for transporting the extracted negative ions to the semiconductor processing unit 23 using a carrier gas are installed.

  The carrier gas supply pipe 31b and the ion supply pipe 31d are installed so as to face each other so that negative ions are smoothly transferred by the carrier gas introduced into the processing chamber 31.

  Negative ions collide with walls or bind to other chemical species and lose their activity. For this reason, the inner diameter of the ion supply tube 31d is set as large as possible, and the length is set as short as possible. Further, the inner wall of the ion supply pipe 31d is formed of fluorocarbon (particularly PTFE; tetrafluoroethylene resin), Teflon (registered trademark), or the like that does not easily react with negative ions. Further, the ion supply pipe 31d is grounded or held at a negative potential during the processing so as not to attract negative ions.

  Further, an inert gas, preferably an inert gas containing a raw material (hydrogen gas) is used as the carrier gas in order to maintain an oxygen-reduced atmosphere from the generation of ions to the treatment chamber. By containing the source gas, there is an effect of maintaining the activity of negative ions (reducing recombination).

  Further, in order to keep the flow rate of the carrier gas high, the region to which the carrier gas is supplied (the region above the extraction electrode 46 described later in the processing chamber 31) is a range in which negative ions do not collide with the wall or the like. It is preferable to set as narrow as possible.

A thermometer 41 that measures the temperature in the processing chamber 31 and a pressure gauge 42 that measures the pressure in the processing chamber 31 are installed on the wall of the processing chamber 31.
Inside the processing chamber 31, a heater 43, a contact electrode 44, an electrode support member 45, and an extraction electrode 46 are installed.

  The heater 43 is installed at substantially the center in the processing chamber 31 and heats the negative ion source S disposed in the processing chamber 31 to a predetermined temperature described later. Inside the heater 43, a gas flow path 43a is formed which is connected to the source gas supply pipe 31a and jets the source gas introduced through the source gas supply pipe 31a from the surface of the heater 43.

  The contact electrode 44 is manufactured in a state of being attached to the negative ion source S. The contact electrode 44 is made porous so as to have a through-hole having a size through which the source gas passes, and is manufactured to have a three-phase interface of the source gas, the negative ion source S, and the contact electrode 44. As a manufacturing method of the contact electrode 44, for example, there is a method in which fine powder is molded into a film shape and sintered, or a method of depositing a film by sputtering or vapor deposition. In order to increase the contact area with the source gas, the contact electrode 44 may be formed in a net shape having a plurality of openings 44a as shown in FIG.

  The contact electrode 44 is electrically connected to the cathode of the high-voltage power supply 32 for applying an electric field. In order to prevent a large amount of source gas from flowing out from the gap between the contact electrode 44 and the heater 43, the gap between the source gas 44 and the heater 43 is held by the protruding member 43b to maintain airtightness.

Substances that can be used for the contact electrode 44 include: (1) a perovskite type proton-conductive (ABO ₃ ) double oxide doped, (2) a substance containing hydride ions, and (3) a ceria-based substance. There are substances, or (4) substances with high ion conductivity such as metals that are stable in a reducing atmosphere.

Examples of the substance corresponding to the above (1) include Sr (Ce, In) O ₃ : strontium cerate, barium cerate-indium dope, Ca (Zr, In) O ₃ : calcium zirconate-indium dope, LaAlO ₃ : Examples include lanthanum aluminate and lanthanum aluminate.

Substances corresponding to the above (2) include MgO: H (magnesia MgO reduced in hydrogen) and LaSrCoO ₃ H _0.7 (K ₂ NiF ₄ type (perovskite related structure) lanthanum strontium cobaltate). Topochemical (maintaining structure) hydrogen substitution).

Examples of the substance corresponding to the above (3) include GDC (20 mol% GdO _1.5 -CeO ₂ ): gadolinium-containing ceria and SDC (20 mol% SmO _1.5 -CeO ₂ ): samarium-containing ceria.

  Examples of the substance corresponding to the above (4) include Pt, Au, and Ag. When the processing temperature is relatively low, another metal can be used as the contact electrode 44.

  One end of the electrode support member 45 is fixed to the wall of the processing chamber 31. The electrode support member 45 supports the extraction electrode 46 so as to face the contact electrode 44. Since the carrier gas for carrying negative ions is supplied to the upper part in the processing chamber 31, the extraction electrode 46 is disposed at a position lower than the installation positions of the carrier gas supply pipe 31b and the ion supply pipe 31d. Is done.

  The extraction electrode 46 is an electrode formed in a shape through which negative ions extracted from the negative ion source S can pass. For example, the extraction electrode 46 is composed of a metal electrode or a ceramic electrode formed in a net shape or a composite material thereof. Further, for example, a disk shape having a hole at the center may be used. Examples of the metal that can be used for the extraction electrode 46 include Pt and Au having reduction resistance (hydrogenation resistance).

  The high-voltage power supply 32 has a cathode connected to the contact electrode 44 via a wiring passing through the heater 43 and an anode connected to the extraction electrode 46 via a wiring passing through the electrode support member 45. The high voltage power supply 32 applies an electric field having a strength described later to the negative ion source S by applying a voltage having a predetermined magnitude between the contact electrode 44 and the extraction electrode 46. Thereby, negative ions are extracted from the negative ion source S heated to a predetermined temperature.

  The source gas supply device 33 is connected to the processing chamber 31 via a source gas supply pipe 31a. The raw material gas supply device 33 supplies a raw material gas (hydrogen gas or a mixed gas of hydrogen gas and inert gas) for replenishing a negative ion source S from which negative ions have been extracted, to a raw material gas supply pipe. It supplies in the processing chamber 31 via 31a.

  The source gas supplied by the source gas supply device 33 is ejected from the surface of the heater 43 through the gas channel 43a formed in the heater 43 through the source gas supply pipe 31a. The ejected source gas is supplied to the three-phase interface of the negative ion source S, the contact electrode 44 and the source gas via the contact electrode 44.

Further, the source gas supply device 33 is configured such that the total gas pressure and the raw material partial pressure on the back surface side of the contact electrode 44 are equal to the total gas pressure and the raw material partial pressure on the extraction electrode 46 side of the negative ion source S or The source gas is supplied so that it is slightly higher. For example, when the pressure on the extraction electrode 46 side of the negative ion source S is set to 4000 Pa and the partial pressure of the raw material 400 Pa by an inert gas containing 10% of the raw material gas, the total pressure on the back side of the contact electrode 44 is An inert gas containing 10% of the raw material gas is supplied so that 1.3 × 10 ⁴ Pa and the partial pressure of the raw material are 1300 Pa. By providing such a partial pressure difference, a concentration gradient of target ions in the negative ion source S is created, and negative ions can be easily extracted.

  The gas exhaust device 34 includes an exhaust pump and the like, and is connected to the processing chamber 31 via a gas exhaust pipe 31c. The gas exhaust device 34 exhausts the gas in the processing chamber 31 and sets the pressure in the processing chamber 31 to a pressure described later.

  The carrier gas supply device 35 is connected to the processing chamber 31 via a carrier gas supply pipe 31b. The carrier gas supply device 35 uses an inert gas such as argon, helium or nitrogen, hydrogen gas, or a mixed gas thereof as a carrier gas for transporting negative ions extracted from the negative ion source S in the processing chamber 31. Supply. At this time, the carrier gas supply device 35 uses a relatively high flow rate (for example, 50 cm / s) in order to prevent negative ions from losing their activity due to collision with walls or other chemical species. Then, the carrier gas is supplied into the processing chamber 31.

The halogen supply device 22 is connected to the processing chamber 51 of the semiconductor processing unit 23 through the ion supply pipe 31d, and the halogen gas (F ₂ , Cl ₂ , Br ₂ , I _2, etc.) described later is supplied into the processing chamber 51. To supply.

  The semiconductor processing unit 23 includes a processing chamber 51 and a gas exhaust device 52, and removes by-products attached to the inner wall and the like of the processing chamber 51 using supplied negative ions and halogen gas. .

  The processing chamber 51 is made of, for example, aluminum, and is connected to the processing chamber 31 of the ion supply unit 21 and the halogen supply device 22 through the above-described ion supply pipe 31d. The processing chamber 51 is provided for performing a predetermined process related to the manufacture of a semiconductor device such as a film forming process or an etching process on the semiconductor wafer.

  The processing chamber 51 includes a susceptor 51 a for placing a semiconductor wafer, a heater 51 b for heating the processing chamber 51, a thermometer 51 c for measuring the temperature in the processing chamber 51, and the inside of the processing chamber 51. A pressure gauge 51d is installed for measuring the pressure.

  Note that the temperature in the processing chamber 51 heated by the heater 51b is set to a temperature suitable for reducing by-products by negative ions and gasifying them by halogen gas.

  For example, if the temperature in the processing chamber 51 is too high, there may be a case where a reaction other than by-products (such as the processing chamber 51 itself or the susceptor 51a) with negative ions or halogen gas tends to occur. On the other hand, when the temperature in the processing chamber 51 is too low, the reaction between the by-product, the negative ions, and the halogen gas may not easily proceed.

  Therefore, the temperature in the processing chamber 51 when removing the by-product is set to 100 to 400 ° C., preferably 200 to 300 ° C. Thereby, substantially only a by-product can be removed appropriately.

  The gas exhaust device 52 is connected to the processing chamber 51 via a gas exhaust pipe 54. The gas exhaust device 52 includes an exhaust pump or the like, exhausts the gas in the processing chamber 51, and sets the pressure in the processing chamber 51 to a predetermined pressure (for example, 133 to 667 Pa (1 to 5 Torr)).

  The control device 24 is composed of a microcomputer or the like, and stores a program for removing by-products generated in the processing chamber 51 of the semiconductor processing unit 23. The control device 24 controls operations of the ion supply unit 21, the halogen supply device 22, and the semiconductor processing unit 23 according to the stored program, and removes by-products in the processing chamber 51.

  For example, the control device 24 controls the heater 43 and sets the temperature in the processing chamber 31 to a predetermined temperature using the measurement result of the thermometer 41. Further, the control device 24 controls the gas exhaust device 34 and uses the measurement result of the pressure gauge 42 to set the inside of the processing chamber 31 to a predetermined pressure. In addition, the control device 24 controls the high voltage power supply 32 and applies an electric field having a predetermined strength to the negative ion source S. The control device 24 controls the carrier gas supply device 35 to supply the carrier gas and supply negative ions to the semiconductor processing unit 23. Further, the control device 24 controls the halogen supply device 22 to supply halogen gas to the semiconductor processing unit 23. The control device 24 controls the heater 51b and heats the inside of the processing chamber 51 to a predetermined temperature using the measurement result of the thermometer 51c. In addition, the control device 24 controls the gas exhaust device 52 and sets the inside of the processing chamber 51 to a predetermined pressure using the measurement result of the pressure gauge 51d.

  Next, the temperature of the negative ion source S heated by the heater 43, the voltage applied by the high voltage power source 32, the pressure in the processing chamber 31 set by the gas exhaust device 34, and the halogen supply device 22 The amount of halogen gas to be supplied will be described.

  Negative ions in the negative ion source S are taken out by heating the negative ion source S and applying an electric field. At this time, if the temperature of the negative ion source S is too low, the negative ions in the negative ion source S are not activated, making it difficult to extract the negative ions. On the other hand, if the temperature of the negative ion source S is too high, activated negative ions may be abnormally generated and the negative ion source S may be denatured. Furthermore, if the heating temperature is too high, a special ceramic or metal having high heat resistance must be used for the heater 43 and the electrode installed in the processing chamber 31.

  For this reason, the temperature of the negative ion source S heated by the heater 43 can easily extract negative ions from the negative ion source S, and can be used with a material such as a general metal, 250 to 1000 ° C. The temperature is preferably set to 400 to 800 ° C, more preferably 700 ° C.

  By applying an electric field to the negative ion source S heated to a suitable temperature as described above, negative ions contained in the negative ion source S can be taken out.

  The magnitude of the voltage applied by the high-voltage power supply 32 is set according to the size (or cleaning area, etc.) of the processing chamber 51 to be cleaned. In other words, the magnitude of the voltage is set so that the strength of the electric field applied to the negative ion source S is strong enough to extract the amount of negative ions necessary for reduction of the by-product.

Generally, when a semiconductor wafer is disposed on the lower surface in the processing chamber, the by-product mainly adheres to the upper and side surfaces in the processing chamber. For example, in a cylindrical processing chamber for a 300 mm wafer, assuming that Ta ₂ O ₅ with a thickness of 1 μm attached to the upper and side 1570 cm ² (φ400 mm, height 25 mm) ranges, all Ta ₂ O ₅ is reduced. In order to do this, 3.0 × 10 ⁻² mol of hydride ions are required. The negative ion current and 10～100Myuei, hydrogen gas was 100sccm corresponds mixed in a carrier gas, maintain the activity of the hydride ions (reducing recombination) that is, the subject in about 4 minutes treatment time Ta ₂ O ₅ can be reduced.

In order to further remove the reduced Ta, a volatile compound can be formed and removed using a halogen gas such as fluorine F ₂ . The halogen gas is suitable to be supplied in an amount equal to or twice that of hydride ions. For example, in the case of the processing chamber of the above-mentioned size, the reactant can be removed as a volatile component by supplying negative ions under the conditions of 133 Pa and 200 ° C. and injecting fluorine gas equivalent to 200 sccm.

Assuming that Al ₂ O ₃ having a thickness of 1 μm adheres to the upper and side surfaces of 1570 cm ² in the processing chamber of the above example, in order to reduce all Al ₂ O ₃ , it is 5.6 × 10 6. ^-2 mol of hydride ion is required. The negative ion current and 10～100Myuei, hydrogen gas was 100sccm corresponds mixed in a carrier gas, maintain the activity of the hydride ions (reducing recombination) that is, the subject in about 6 minutes processing time Al ₂ O ₃ can be reduced.

It is also possible to form and remove volatile compounds using an organic acid such as hexafluoroacetylacetone in order to further remove the reduced Al. For example, in the case of the processing chamber of the above-mentioned size, the reactant can be removed as a volatile component in about 10 minutes by supplying 400 sccm of hexafluoroacetylacetone and 200 sccm of N ₂ gas under the conditions of 133 Pa and 300 ° C.

  The amount of current obtained from the negative ion source S increases as the size of the negative ion source S (area of the surface from which ions are extracted) increases and increases as the applied electric field increases.

For example, when hydrogen-substituted C12A7 is used as the negative ion source S and the negative ion source S is heated to 700 ° C., a current amount of about 0.1 μA / cm ² can be obtained by applying an electric field of 400 V / cm. .

  Therefore, the intensity of the electric field applied to the negative ion source S (that is, the magnitude of the voltage applied by the high-voltage power supply 32) depends on the size of the negative ion source S and the above-described current amount (10 to 100 μA). It is set to be obtained.

  In order to supply negative ions to the processing chamber 51 of the semiconductor processing unit 23, the atmosphere and pressure of the processing chamber (negative ion generation chamber) 31 when taking out negative ions from the negative ion source S are the same as the inert gas or the inert gas. A pressure higher than that of the processing chamber 51 is set in an atmosphere containing the source gas and reducing oxygen.

For example, when the inside of the processing chamber 51 of the semiconductor processing unit 23 is set to 133 to 667 Pa (1 to 5 Torr), the pressure in the processing chamber 31 uses an inert gas containing 10% of a raw material (hydrogen gas), It can be set to 1000 to 1.01 × 10 ⁵ Pa (7.5 to 760 Torr), preferably 1000 to 10000 Pa (7.5 to 75 Torr).

Among these pressure ranges, at atmospheric pressure, a usable electric field range that does not cause discharge in the processing chamber 31 is 200 to 1500 V / cm, and a preferable pressure range is 200 to 600 V / cm. At this time, the range of ion currents that can be generated is 0.05 to 0.15 μA / cm ² . A more preferable applied electric field is 400 V / cm, and the ion current at this time is 0.1 μA / cm ² .

For example, as an area corresponding to drawing out an ion current of 10 to 100 μA necessary for reducing Ta ₂ O ₅ adhering in the processing chamber for the 300 mm wafer described above, 200 to 1000 cm from the above preferred electric field range. ^It suffices if there is an area of the negative ion source S facing the ^two electrodes. Specifically, for example, if the shape is a disk having a diameter of 16 to 36 cm, an ion current of 20 to 100 μA can be extracted with an applied electric field of 400 V / cm.

  If the supply amount of the halogen gas is too large, things other than the by-products are likely to react with the halogen gas, whereas if it is too small, the by-products cannot be sufficiently removed.

  Therefore, the supply amount of the halogen gas is set according to the size (or cleaning area, etc.) of the processing chamber 51 to be cleaned. In other words, the supply amount of the halogen gas is set to an amount that can sufficiently remove the by-product.

  For example, for a single wafer processing chamber for processing a semiconductor wafer, the supply amount of halogen gas is doubled from the amount equal to the amount of negative ions (or the total amount of hydride ions and hydrogen gas). Is set as follows.

Specifically, for example, when removing Ta ₂ O ₅ adhering to the processing chamber for 300 mm wafer described above, when the negative ion current is 100 μA and the flow rate of hydrogen gas contained in the carrier gas is 100 sccm, the flow rate of the halogen gas is 50˜50. It is set to 500 sccm, preferably 100 to 200 sccm.

Further, as a specific example of the organic acid gas for changing the by-product into a volatile substance, when removing Al ₂ O ₃ adhering to the processing chamber for the 300 mm wafer, a negative ion current of 100 μA, a carrier When the hydrogen gas contained in the gas is 100 sccm, it can be set to, for example, hexafluoroacetylacetone 400 sccm and nitrogen gas 200 sccm.

Next, a cleaning operation performed by the above-described apparatus will be described.
The negative ion source S is set in the processing chamber (negative ion generation chamber) 31 in advance.

  In response to the operator's instruction to start cleaning, or when the processing of the number of semiconductor wafers set in the stored program is completed, the control device 24 executes the following cleaning process.

First, the control device 24 controls the gas exhaust device 52 to exhaust the gas remaining in the processing chamber 51.
Then, the control device 24 controls the source gas supply device 33 to supply hydrogen gas (or a mixed gas of hydrogen gas and inert gas) into the processing chamber 31.

Subsequently, the control device 24 controls the gas exhaust device 34 and sets the inside of the processing chamber 31 to the pressure described above using the measurement result of the pressure gauge 42.
Then, the control device 24 controls the heater 43 and heats the negative ion source S set on the contact electrode 44 to about 700 ° C. using the measurement result of the thermometer 41.

Subsequently, the control device 24 controls the carrier gas supply device 35 to supply the carrier gas into the processing chamber 31 at a predetermined flow rate (for example, 10% H ₂ —Ar is 500 sccm).
Thereafter, the control device 24 controls the high voltage power supply 32 to apply a voltage between the contact electrode 44 and the extraction electrode 46, thereby applying the above-described electric field to the negative ion source S.

  Thereby, the negative ions in the negative ion source S are taken out by the applied electric field. The extracted negative ions pass through the extraction electrode 46 and are transferred to the semiconductor processing unit 23 by the carrier gas flowing through the upper portion of the processing chamber 31.

In addition, after supplying negative ions to the semiconductor processing unit 23, the control device 24 controls the halogen supply device 22 to supply halogen gas (for example, F ₂ ) at a predetermined flow rate to the processing chamber of the semiconductor processing unit 23. 51 is supplied.

  The control device 24 supplies negative ions and halogen gas, controls the gas exhaust device 52, and uses a measurement result of the pressure gauge 51d to set a predetermined pressure (for example, 133 Pa (1 Torr) in the processing chamber 51. ).

And the control apparatus 24 controls the heater 51b, and sets the inside of the process chamber 51 to predetermined | prescribed temperature (for example, 200 degreeC) using the measurement result of the thermometer 51c.
Thereby, the by-product adhering to the inner wall or the like of the processing chamber 51 is reduced by the supplied negative ions and gasified by the supplied halogen gas. Specifically, for example, the reactions shown in Chemical Formulas 1 and 2 occur on the inner wall of the processing chamber 51 and the by-products are gasified.
(Chemical formula 1)
Ta ₂ O ₅ + 10H ⁻ → 2Ta + 5H ₂ O ↑
(Chemical formula 2)
2Ta + 5F ₂ → 2TaF ₅ ↑

  As described above, the by-product adhering to the inner wall or the like of the processing chamber 51 is reduced by the supplied negative ions, gasified by the supplied halogen gas, and processed by the gas exhaust device 52 by the gas exhaust device 52. It is discharged outside.

  After maintaining the above state for a predetermined time, the control device 24 stops the supply of negative ions and halogen gas, and ends the cleaning process of the processing chamber 51.

  As described above, negative ions can be obtained by a simple method of heating the negative ion source S and applying an electric field. In other words, the ion supply unit 21 can have a simple configuration. As a result, the cleaning process can be performed at a lower cost than when an expensive plasma source is used.

Further, since negative ions of hydrogen and halogen gas are less reactive than ClF ₃ , the cleaning process can be performed more safely and easily.

  In the above embodiment, an example in which negative ions and halogen gas are supplied to one processing chamber 51 has been described. However, the ion supply unit 21 and the halogen supply device 22 may be connected to the plurality of processing chambers 51 and supply negative ions and halogen gas to the plurality of processing chambers 51.

  Further, in FIG. 3, a shower head type is shown as the negative ion outlet in the processing chamber 51 of the semiconductor processing unit 23. However, depending on the volume of the processing chamber 51 and the setting of the apparatus, other types such as a nozzle type are shown. A thing may be used.

In addition, the configuration of the ion supply unit 21 is not limited to the configuration illustrated in FIG. 3, and may be configured as illustrated in FIGS. 5A to 5C, for example.
Specifically, when the negative ion source S has a disk shape as shown in FIG. 2A, the negative ion source S may be fixed by the clamp 61. In this case, for example, as shown in FIG. 5A, the negative ion source S can be installed vertically.

  In addition, as shown in FIG. 5A, a perforated metal hot plate 62b formed of Ta or Mo that includes a covered heater 62a may be used instead of the heater 43, and absorbs a temperature difference. The hot plate 62b may be installed on the hollow metal tube 63.

  As shown in FIG. 5B, a plurality of lamps 64 may be installed instead of the heater 43, and the negative ion source S may be heated by the radiant heat of the lamps 64. In this case, a quartz window 65 that transmits light is provided between the contact electrode 44 and the lamp 64. Further, in order to concentrate the radiant heat on the negative ion source S, a reflector 66 or the like that reflects the light of the lamp 64 may be installed.

Further, as shown in FIG. 5C, a microwave power source 67 for generating a microwave, a waveguide 68a for propagating the microwave, and a conical quartz glass (waveguide) 68b are installed, and the microwave is installed. The negative ion source S may be heated by In this case, in order to uniformly heat the entire surface of the negative ion source S between the conical quartz glass 68b and the contact electrode 44, SiC or mullite (3Al ₂ O having a high microwave absorption rate and high thermal conductivity is provided. A soaking plate 69 formed of ₃ · 2SiO ₂ ) or the like may be provided.

  Even if the ion supply unit 21 is configured as described above, the negative ions are taken out from the negative ion source S and the by-products attached to the inner wall of the processing chamber 51 are reduced as in the above-described embodiment. Can do.

  Further, the above-described ion supply unit 21 is configured as shown in FIG. 5A, for example, and may be directly connected to the processing chamber 51 as shown in FIG. In this case, an extraction electrode 46 is installed between the ion generation chamber 31 of the ion supply unit 21 and the processing chamber 51. In this case, the extraction electrode 46 also functions as a conductance plate that adjusts the pressure difference between the ion generation chamber 31 and the processing chamber 51. In this way, the transport distance by the carrier gas is short, and the deactivation of hydride ions can be minimized.

  Alternatively, the ion supply unit 21 and the halogen supply device 22 described above may be connected to a batch-type processing chamber to perform the same cleaning process as described above.

  In the above embodiment, hydrogen substitution C12A7 is shown as an example of the negative ion source S containing hydride ions, but other types of negative ion source S for releasing hydride ions may be used. .

Examples of the negative ion source S that emits hydride ions include hydrogen-substituted mayenite and (1) perovskite-type (ABO ₃ ) double oxide having proton conductivity that can be used for the contact electrode 44 described above. A material doped with a material, and (2) a material containing hydride ions.

  In the above, the case where the by-product in the processing chamber 51 is removed using the halogen gas has been described, but an organic acid may be used instead of the halogen gas. In this case, an organic acid supply device is provided instead of the halogen supply device 22, and, for example, a mist-like organic acid is supplied into the processing chamber 51 instead of the halogen gas described above. Even in this case, the cleaning process can be performed in the same manner as described above.

  Further, although it is difficult at a pressure of several Torr order to atmospheric pressure, if possible, negative ions are not supplied into the processing chamber 51 by the carrier gas, and a deflecting device composed of a deflection coil or the like is connected to the processing chamber 51. Then, the extracted negative ion beam may be directly applied to the sidewall of the processing chamber 51 or the like.

It is a block diagram of the ion source production | generation apparatus concerning embodiment of this invention. It is a figure which shows the to-be-processed object used with the ion source production | generation apparatus of FIG. It is a block diagram of the apparatus for performing the cleaning process concerning embodiment of this invention. It is a block diagram of the minus electrode which comprises the apparatus shown in FIG. It is a figure which shows the other structure of the ion supply apparatus which comprises the cleaning apparatus of FIG. It is a figure which shows the other structure of a cleaning apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Processing container 11a Mounting base 11b Cover 11c Gas supply pipe 11d Gas exhaust pipe 12 Raw material gas supply apparatus 13 Gas exhaust apparatus 14 Heat insulation container 15 Heater 16 Heater control apparatus 17 Control apparatus 21 Ion supply unit 22 Halogen supply apparatus 23 Semiconductor processing unit 24 Control device 31 Processing chamber 31a Source gas supply pipe 31b Carrier gas supply pipe 31c Gas exhaust pipe 31d Ion supply pipe 32 High pressure power source 33 Source gas supply apparatus 34 Gas exhaust apparatus 35 Carrier gas supply apparatus 41 Thermometer 42 Pressure gauge 43 Heater 43a Gas Flow path 43b Projection member 44 Contact electrode 44a Opening 45 Electrode support member 46 Extraction electrode 51 Processing chamber 51a Susceptor 51b Heater 51c Thermometer 51d Pressure gauge 52 Gas exhaust device 54 Gas exhaust pipe

Claims (6)

A cleaning device for performing a cleaning process for removing a by-product generated in a processing chamber for performing a predetermined process on a semiconductor wafer,
Ion supply means for reducing the by-product generated in the processing chamber by supplying hydride ions into the processing chamber;
A gasifying agent supplying means for supplying a gasifying agent for gasifying the by-product reduced by the ion supplying means into the processing chamber;
An exhaust means for removing the by-product gasified by the gasifying agent supply means from the process chamber by exhausting the gas in the process chamber;
A cleaning device comprising: The ion supply means includes
Source heating means for heating the negative ion source containing the hydride ions;
An electric field applying means for taking out hydride ions contained in the negative ion source by supplying an electric field to the negative ion source heated by the source heating means, and supplying the hydride ions into the processing chamber;
The cleaning apparatus according to claim 1, comprising:   The cleaning apparatus according to claim 2, wherein the electric field applying unit applies an electric field of 200 to 1500 V / cm to the negative ion source.   The cleaning apparatus according to claim 2, wherein the source heating unit heats the negative ion source to 250 to 1000 ° C.   The cleaning apparatus according to claim 1, wherein the gasifying agent supply means supplies a halogen gas or an organic acid as the gasifying agent into the processing chamber. A cleaning method for removing by-products generated in a processing chamber for performing a predetermined process on a semiconductor wafer,
An ion supply step of reducing the by-product generated in the processing chamber by supplying hydride ions into the processing chamber;
A gasifying agent supplying step of supplying a gasifying agent for gasifying the by-product reduced in the ion supplying step into the processing chamber;
An exhaust step of removing the by-product gasified in the gasifying agent supplying step from the inside of the processing chamber by exhausting the gas in the processing chamber;
A cleaning method comprising:

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