JPH1098019A - Surface cleaning - Google Patents

Abstract

PROBLEM TO BE SOLVED: To clean the surfaces of workpieces and the interior of a manufactuting device system and to enable removing materials having water and hyroxyl groups, which are adsorbed to the surfaces thereof by a method, wherein CO, or a carbon-containing material and an oxygen-containing material are introduced in the manufacturing device system in such a way that the compositional ratio of the CO or the carbon-containing material to the oxygen- containing material is set to a specified extent. SOLUTION: One kind of a carbon-containing compound, consisting of either a compound having an aliphatic hydrocarbon and an aldehyde group and a C-F compound or more than two kinds of carbon-containing compounds, consisting of both compounds and an oxygen- containing material are introduced in a manufacturing device system, in which cleaning of the surfaces of products is performed. Thereafter, CO is generated by applying energy to the carbon-containing compound or carbon-containing compounds and the oxygen-containing material using at least one means out of discharge, a laser, light and heat. The compositional ratio of the CO or the carbon-containing material or carbon-containing materials, which are introduced in the system to the oxygen-containing material, which is introduced into the system, is set to the range of C:O=1:200 to 1:5 in a mol ratio obtainable in terms of carbon and oxygen atoms. Thereby, residual water on the surfaces of the products can be removed, without contaminating the surfaces of the products.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface cleaning method for cleaning the surface of a workpiece to be processed in a reduced-pressure manufacturing apparatus system and / or the inside of the manufacturing apparatus system and for dehydrating the surface. In particular, the present invention relates to a surface cleaning method for removing a substance having moisture and a hydroxyl group adsorbed on a manufacturing apparatus, that is, a process chamber and / or a wafer surface in order to stabilize the apparatus and the process in manufacturing a semiconductor device.

[0002]

2. Description of the Related Art In general, various vacuum apparatuses such as an ion implantation apparatus, a CVD apparatus, and an etching apparatus are used in a semiconductor manufacturing apparatus. In each case, processing is performed on a wafer under a low pressure, but these apparatuses need to be opened to the atmosphere in a certain cycle to perform chamber cleaning. Therefore, immediately after the cleaning, moisture in the atmosphere is adsorbed on the inner wall of the process chamber, and moisture that cannot be sufficiently removed by conventional long-time evacuation or empty discharge remains. The residual moisture is consumed and reduced by capturing halogen atoms by hydrogen atoms and releasing oxygen atoms by contacting the plasma. Therefore, the concentration of active species for film formation and etching changes along with the change in residual moisture concentration during the cleaning cycle, and as a result, the film quality and etching shape change. Wipe the inner wall with volatile substances such as. However, alcohol has a hydroxyl group in the molecule, and the hydroxyl group remains to adsorb water.

[0003] In addition, although the wafer is carried into the process chamber from the atmosphere via the load lock chamber, it cannot be evacuated for a long time due to the limitation of the throughput, and almost no moisture or hydroxyl groups adsorbed on the wafer. It is brought into the process chamber as it is. As a countermeasure against this, in a sputtering apparatus or the like, a method of evacuating the entire cassette in a load lock chamber or heating the cassette to 200 ° C. to 300 ° C. in a transfer chamber before entering a process chamber (see JP-A-6-330307). is there. Prior to the application of a photoresist, a process of removing water by wiping a wafer with HMDS (hexamethyldisilazane) in order to enhance adhesion or a method using microwave heating in combination with this method (Japanese Patent Application Laid-Open No. 57-55928) Publications) are proposed.

However, the above-mentioned conventional surface cleaning method has the following problems. 1. The semiconductor manufacturing apparatus that has been opened to the atmosphere and the chamber has been cleaned has moisture in the atmosphere adsorbed on the inner wall as described above,
Water that cannot be sufficiently removed by conventional long-time evacuation or empty discharge remains. Even if the inner wall is wiped with a volatile substance such as alcohol or acetone, most of the volatile substance evaporates, and water remains. The residual moisture is consumed by contacting the plasma with hydrogen atoms in the water molecules capturing halogen atoms and releasing oxygen atoms, and is reduced. Therefore, during the cleaning cycle, the concentration of the active species for film formation and etching changes along with the change in the residual moisture concentration, and as a result, the film quality and etching shape change. In etching, halogen is often used as a main etchant. At this time, if a hydrogen atom is present in the apparatus, the hydrogen atom is bonded to the etchant, and the processing rate is tapered due to a decrease in etch rate and promotion of deposition of a sidewall protective film. . That is, since the processing shape (processing size) varies between chamber cleaning cycles, the residual water contributes to limiting the processing accuracy.

[0005] 2. It is not only the residual moisture after cleaning the apparatus that limits the processing accuracy. In the case of a single-wafer type device that is transferred from the load lock chamber to the process chamber,
The moisture adsorbed on the wafer surface is hardly removed in the load lock chamber mainly for evacuation and is carried into the process chamber. Even when the entire cassette is evacuated, it is difficult to remove the adsorbed moisture only by evacuation. Further, since a wafer to be etched has a resist mask on the surface, high-temperature heating cannot be used. If moisture is present on the surface during etching, the processing shape becomes tapered at the beginning of etching as described above, and moisture and the deposits promoted by the processing accumulate in the chamber due to continuous processing, so that the reproducibility of processing dimensions Worsens. As the miniaturization progresses and the aspect ratio becomes higher, the vertical shape is required, and the ratio of the dimensional change due to the taper at the initial stage of the etching and the dimensional change at the time of the continuous processing cannot be ignored.

[0006] 3. HMD for dewatering small parts
Surface dehydration treatment using S (hexamethyldisilazane) or a method using microwave heating in combination with the surface dehydration treatment (JP-A-57-4
However, in the dehydration processing of a large-scale non-wafer-level component such as a semiconductor device, the HM
Due to the property that DS ignites at about 200 ° C., the degree of freedom of use is limited.

The above-mentioned various problems can be said not only in a semiconductor manufacturing system such as a process chamber or a load lock chamber, but also in an apparatus which is generally used under reduced pressure and which needs to remove adsorbed moisture on the surface. Therefore, there is a demand for a method for effectively removing the surface adsorbed moisture in the reduced-pressure production system.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of various problems based on the above-mentioned prior art, and an object of the present invention is to provide a manufacturing apparatus which performs processing under reduced pressure.
In order to stabilize the manufacturing equipment and the manufacturing process, eliminate the variation in the degree of processing of the workpiece, and obtain stability, clean the surface of the workpiece and the inside of the manufacturing equipment system, and remove the moisture adsorbed on the surface and An object of the present invention is to provide a surface cleaning method for removing a substance having a hydroxyl group.

[0009]

In order to achieve the above object, the present invention provides a method for cleaning the surface of a workpiece to be processed in a reduced pressure production system and / or for cleaning the interior of the production system. Then, a CO or carbon-containing substance and an oxygen-containing substance are introduced into the production system so that the molar ratio of carbon atoms to oxygen atoms is in the range of C: O = 1: 200 to 1: 5. A method for cleaning a surface is provided.

It is preferable that the carbon-containing substance is one or more carbon-containing compounds selected from the group consisting of a compound having an aliphatic hydrocarbon, an aldehyde group, and a CF compound.

[0011] In the above method for cleaning a surface, the method may further comprise:
Alternatively, the present invention provides a surface cleaning method in which one or both of an inert gas and a hydrogen-containing gas are added to a mixed gas of the carbon-containing material and the oxygen-containing material.

[0012] The present invention provides the method for cleaning a surface, wherein the method further comprises applying energy to the manufacturing apparatus system by at least one of electric discharge, laser, light, and high heat.

[0013] An object of the present invention is to provide a method of cleaning a surface, wherein the manufacturing process performed on the workpiece is a semiconductor manufacturing process.

The inside of the manufacturing apparatus system provides a method for cleaning a surface which is in the manufacturing apparatus system after maintenance.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The surface cleaning method according to the present invention will be described below in more detail. The surface cleaning method of the present invention is characterized in that at least a CO or carbon-containing substance and an oxygen-containing substance are introduced into a manufacturing system for processing a workpiece under reduced pressure. Since CO is excellent in reducing properties, it combines with the adsorbed moisture on the inner wall of the manufacturing equipment or on the surface of the product to be processed and oxygen of the substance having a hydroxyl group to form CO.
Generates ₂ and hydrogen. Since both products are gaseous, residual moisture can be removed without contaminating the product surface.

As the carbon-containing substance, it is preferable to use one or more carbon-containing compounds of an aliphatic hydrocarbon, a compound having an aldehyde group, or a CF compound. Specific examples of the aliphatic hydrocarbon include lower aliphatic hydrocarbons such as methane, ethane, and propane. Specific examples of the compound having an aldehyde group include compounds such as formaldehyde, acetaldehyde, and acetaldehyde dimethyl acetal. Specific examples of the CF compound include CF ₄ , C ₂ F ₆ , C ₃ F ₈ , C ₄
F ₈ and CHF ₃ can be exemplified. Examples of the oxygen-containing substance include oxygen, nitrous oxide, and oxygen difluoride.

One or more carbon-containing compounds, such as aliphatic hydrocarbons, compounds having an aldehyde group, or C-F compounds, and oxygen-containing substances are incorporated into a manufacturing system for cleaning the surface. After being introduced, discharge, laser,
CO can be generated by applying energy by at least one of light and heat. The composition ratio of CO or the above-mentioned carbon-containing substance and the above-mentioned oxygen-containing substance introduced into the production apparatus system is the molar ratio of CO or the above-mentioned carbon-containing substance and the above-mentioned oxygen-containing substance in terms of carbon atoms and oxygen atoms. C: O = 1: 200 to 1:
It is preferably in the range of 5. This is because in this range, CO is generated and carbon deposits are not generated. Further, the mixing ratio of the carbon-containing substance and the oxygen-containing substance is preferably in the range of 1: 2.5 to 1:20 in terms of the partial pressure in terms of CO and O ₂ , since it is possible to efficiently generate CO. .

In order to introduce CO or the above-mentioned carbon-containing substance and the above-mentioned oxygen-containing substance into the production system for cleaning the surface, these gases and one or both of an inert gas and a hydrogen-containing gas are used. May be mixed, and this mixed gas may be introduced. As an inert gas, He,
Rare gases such as Ne and Ar and hydrogen-containing gases include H ₂ ,
A gas such as NH ₃ can be used. These gases are
Any one or two or more of them may be used. The mixing ratio of CO in the system for performing surface cleaning and any one or both of an inert gas and a hydrogen-containing gas is 1:20 to 1: 100 as a partial pressure ratio of each. This is preferable because the decrease in CO concentration due to dilution is suppressed and the reaction is promoted.

Prior to introducing the mixed gas into a manufacturing system for cleaning the surface, it is preferable to evacuate the manufacturing system. The degree of reduced pressure in the production system when the mixed gas is introduced is preferably set to 0.1 to 2 Torr. This is because the surface cleaning and dehydration by the mixed gas are efficiently advanced. The amount of the mixed gas introduced into the depressurized production system is preferably 1 to 10% of the internal volume of the production system as a flow rate per minute. If the amount is larger than the above range, carbon is undesirably deposited on the inner wall of the manufacturing apparatus or the surface of the workpiece in the manufacturing apparatus system. The gas flow rate can be adjusted by a mass flow controller or the like.

The introduced mixed gas is energized by at least one of electric discharge, laser, light, and heat in the production equipment system, and the CO activated by this is reduced in the production equipment system. , And reacts with a substance having water or a hydroxyl group adsorbed on a workpiece in the manufacturing apparatus system or on an inner wall of the manufacturing apparatus to form CO ₂ and H ₂ .
Since both CO ₂ and H ₂ are gases, they can be exhausted to the outside of the manufacturing system without deposits remaining. Examples of the discharge include discharges such as RIE, MERIE, ECR, and helicon waves, a laser such as a CO ₂ laser, light as ultraviolet light and infrared light, and heat as lamp annealing heat and heater heating. be able to. The energy applied to the mixed gas only needs to be sufficient to activate CO in the mixed gas. The time for introducing the mixed gas and continuing the reaction between the adsorbed water and the CO varies depending on the volume of the manufacturing apparatus and the tolerance of the residual amount of the adsorbed water in the manufacturing apparatus system, and may be appropriately determined. After the water removal process, the inside of the manufacturing system is further evacuated to remove the mixed gas, CO ₂ , and H ₂ from the inside of the manufacturing system. Is also different, and may be determined appropriately.

The above-described dehydration reaction by CO is effective for removing the surface of a workpiece to be processed in a reduced-pressure manufacturing apparatus system and moisture adsorbed in the manufacturing apparatus system. Also,
If the manufacturing apparatus includes a step that requires removal of moisture adsorbed on the surface, the surface cleaning method of the present invention can be suitably applied. For example, such a manufacturing apparatus includes ECR
An etching apparatus, a plasma CVD apparatus, and the like can be given. In particular, the surface cleaning method of the present invention can be used in a manufacturing process of a semiconductor manufacturing apparatus, and specifically, a pre-process of vapor phase film formation, a pre-process of forming an insulating film or a metal wiring film, and a photoresist coating process. It can be suitably used in a pretreatment step and a pretreatment step of etching.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The surface cleaning method of the present invention will be specifically described below based on preferred embodiments of the present invention.

Here, an example of application of the present invention to contact hole etching using the ECR etching apparatus shown in FIG. 1 will be described. As shown in FIG. 1, the inside of the etching chamber 12 is exhausted from an exhaust port 14 by a turbo-molecular pump and a dry pump, and a desired flow rate of each etching gas is introduced into the etching chamber 12 by a mass flow controller 16 to generate plasma. Is done.
The wafer 18 is supported on the lower electrode 20 by an electrostatic chuck mechanism.
During zero, the chiller 22 is filled with He gas.
The heat conduction between the wafer stage 10 and the wafer 18 cooled by the above is secured. An RF bias for increasing anisotropy can be applied to the wafer stage 10. In FIG. 1, reference numeral 24 denotes a magnetron, 26 denotes a waveguide,
8 is a discharge tube, 30 is an electromagnetic coil, 32 is a gas introduction tube, 3
4 denotes a wafer transfer port, and 36 denotes an RF power source.

In the embodiment of the present invention, C ₄ F ₈ was used as a main gas for contact etching, and CO, O ₂ , and Ar were used as main gases for a water removal process. Mixing ratio of the mixed gas, the CO 4.5% ,, O ₂ 50% was 45.5 percent Ar. This mixed gas was radicalized and reacted by plasma discharge. Interlayer film is BPSG film about 1μm
And

As a comparative example, contact hole etching was performed in the same manner as in the example of the present invention, except that only normal vacuum evacuation was performed without performing the water removal process.

(Example 1, Comparative Example 1) FIG. 2 shows that after chamber cleaning, evacuation was performed for 5 hours and the degree of pressure reduction was 10%.
^-5 Torr, the change with time in the average contact diameter when contact etching is performed (Comparative Example 1), and the CO-O for 30 minutes after the degree of pressure reduction becomes 10 ^-4 Torr by vacuum evacuation for 3 hours after cleaning. _The change with time of the average contact diameter when the _2- Ar-based discharge is performed and then the contact etching is performed (Example 1) is shown. At this time, the flow rate of the main gas in the water removal process was 1200 sccm. The vertical axis of FIG. 2 shows the dimensional variation of the contact hole, where the target hole diameter is represented as 1. The abscissa indicates the accumulated time (hr) from immediately after the chamber cleaning to 30 hours later.
Is shown in units. In the actual manufacturing process, the chamber cleaning is performed approximately every 30 hours. Therefore, as a rough guide, the integrated processing time (or RF time) is set to 3 hours.
Up to 0 hours. In Comparative Example 1 in which only evacuation was performed for 5 hours, the hole diameter was reduced by 15% or more at first due to the effect of residual moisture. However, in Example 1 in which CO-O ₂ -Ar-based discharge was performed for 30 minutes, Even when the vacuum evacuation was performed for 3 hours, the diameter of the contact hole was reduced about 6% immediately after the startup. Thus, it can be seen that in the etching apparatus, that is, in the semiconductor manufacturing apparatus, the variation in the processing size between the chamber cleaning cycles can be greatly suppressed.

(Embodiment 2, Comparative Example 2) FIG.
Contact etch with only load lock exhaust
(Comparative Example 2), exhaust gas in the load lock chamber and
15 seconds / CO-O of wafer _Two-In case of Ar discharge
(Example 2) Contact hole during continuous processing of 50 wafers
Shows the variation in diameter. In both Example 2 and Comparative Example 2, the device
The test was performed 15 hours after the leaning. Note that CO
-O_TwoThe flow rate of the -Ar gas was 50 sccm. Normal
In Comparative Example 2 where only the load lock exhaust was
Although the contact diameter is reduced by about 7% by
Lock lock exhaust and 15 seconds / wafer CO-O_Two-Ar system
In Example 2 of the present invention in which discharge was performed, the reduction ratio was about 2%.
It has been suppressed. Thus, semiconductor devices, especially edges,
In the chucking device, moisture absorbed from the wafer into the chamber
Photomask dimensions on the wafer surface
Removal of adsorbed water with little change in water
To ensure high dimensional stability in continuous processing.
It can be seen that this is possible.

As described above, the present invention has been described based on the embodiments. However, the present invention is not limited to the above-described embodiments, and may be another etching step or a wafer cleaning step.
Further, the process of removing water from the wafer may be performed in a preliminary chamber such as a load lock chamber instead of the process chamber. Further, the present invention is not limited to the semiconductor manufacturing process, but may be applied to any process that requires removal of water adsorbed on the surface.

[0029]

As described in detail above, according to the surface cleaning method of the present invention, at least CO or a raw material generating the same is introduced into the reduced-pressure production system, whereby the surface to be cleaned is removed. The substance having the adsorbed moisture and the hydroxyl group on the surface can be decomposed into CO ₂ and H ₂ , and as a result, the substance having the adsorbed moisture and the hydroxyl group can be removed. For this reason, in a manufacturing apparatus system for processing an object to be processed under reduced pressure, fluctuations in processing dimensions between cleaning cycles of the manufacturing apparatus can be significantly suppressed. Also, with respect to carry-in of adsorbed moisture from the workpiece into the manufacturing apparatus system, the adsorbed moisture can be removed without substantially changing the processing dimensions of the workpiece surface, and high dimensional stability is ensured in continuous processing. be able to.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of an example of an ECR etching apparatus using a surface cleaning method of the present invention.

FIG. 2 is a graph showing the change over time of the average contact diameter during contact etching when only vacuum evacuation is performed in Comparative Example 1 and when vacuum evacuation is performed in Example 1 and the surface cleaning method of the present invention is further performed. It is.

FIG. 3 shows a case where only the exhaust is performed in the load lock chamber in Comparative Example 2 and a case where the exhaust is performed in the load lock chamber and the surface cleaning method of the present invention is performed in the load lock chamber in Example 2 when 50 sheets are continuously processed. 4 is a graph showing a change over time in a hole diameter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Wafer stage 12 Etching chamber 14 Exhaust port 16 Mass flow controller 18 Wafer 20 Lower electrode 22 Chiller 24 Magnetron 26 Waveguide 28 Discharge tube 30 Electromagnetic coil 32 Gas introduction tube 34 Wafer entrance 36 RF power supply

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI C23G 5/00 C23G 5/00 H01L 21/205 H01L 21/205 21/3065 21/302 N

Claims (6)

[Claims] In order to clean the surface of a workpiece to be processed in a reduced pressure production system and / or the interior of the production system, a CO or carbon-containing substance is provided in the production system. A method for cleaning a surface, comprising introducing an oxygen-containing substance in a molar ratio of carbon atoms to oxygen atoms in a range of C: O = 1: 200 to 1: 5. 2. The carbon-containing substance is one or more carbon-containing compounds selected from the group consisting of aliphatic hydrocarbons, compounds having an aldehyde group, and CF compounds. The method for cleaning a surface according to claim 1. 3. The method for cleaning a surface according to claim 1, wherein the mixed gas of CO or the carbon-containing substance and the oxygen-containing substance is one of an inert gas and a hydrogen-containing gas. A method for cleaning a surface, comprising adding a seed or both. 4. The method for cleaning a surface according to claim 1, further comprising the steps of:
A method for cleaning a surface, comprising applying energy by at least one of laser, light and high heat. 5. The surface cleaning method according to claim 1, wherein the manufacturing process performed on the workpiece is a semiconductor manufacturing process. 6. The surface cleaning method according to claim 1, wherein the inside of the manufacturing apparatus system is inside the manufacturing apparatus system after maintenance.