Substrate processing method, substrate processing apparatus, substrate processing system and recording medium

A substrate processing method can remove a part of a processing target film formed on a surface of a substrate W under a normal pressure atmosphere while suppressing an influence upon the substrate. A source material of the processing target film, which is decomposed by irradiating an ultraviolet ray thereto under an oxygen-containing atmosphere, is coated on the substrate W, and the processing target film is formed by heating the source material coated on the substrate W. Then, the substrate W having thereon the processing target film is placed within a processing chamber under the oxygen-containing atmosphere where a gas flow velocity is equal to or smaller than 10 cm/sec, and the part of the processing target film is removed by irradiating the ultraviolet ray to the substrate W.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Japanese Patent Application Nos. 2014-128430 and 2015-087675 filed on Jun. 23, 2014 and Apr. 22, 2015, respectively, the entire disclosures of which are incorporated herein by reference.

TECHNICAL FIELD

The embodiments described herein pertain generally to a technique of processing a processing target film by irradiating an ultraviolet ray to a substrate.

BACKGROUND

In a manufacturing process for a semiconductor device having, for example, a multilayer wiring structure, a resist coating process of forming a resist film by coating a resist liquid on a semiconductor wafer (hereinafter, referred to as “wafer”), an exposure process of exposing the resist film to have a preset pattern, a developing process of developing the exposed resist film, and so forth are performed in sequence. Through these processes, a resist pattern is formed on the wafer. Then, an etching process is performed on the wafer by using the resist pattern as a mask. Then, a removing process of removing the resist film or the like is performed, so that the preset pattern is formed on the wafer. By repeating these processes of forming a pattern on each of stacked layers multiple times, a semiconductor device having a multilayer wiring structure is manufactured.

When patterns are formed on the wafer repeatedly, however, a surface to be coated with the resist film needs to be planarized in order to form the resist film of the (n+1)thlayer to an appropriate height after a pattern is formed on the nthlayer.

Conventionally, to this end, after a processing target film is formed on the pattern of the wafer, a surface of the processing target film is planarized. The processing target film may be formed by using a method involving the processes of: coating a source material on the wafer; forming the processing target film by heating the coated source material; and removing a surface of the processing target film by etching back the processing target film through the use of, for example, a dry etching method (reactive ion etching method), as described in Patent Document 1, for example. Hereinafter, the processing target film coated and formed for the planarization of the substrate will be referred to as a SOC (Spin On Cap) film.

When using the method described in the aforementioned Patent Document 1, the coating and the heating of the source material are performed in a normal pressure atmosphere, whereas the etch-back of the SOC film is performed in a vacuum atmosphere. Thus, the process under the normal pressure atmosphere and the process under the vacuum atmosphere are required to be performed in individual systems, and the wafer needs to be transferred between these different systems. As a result, manufacturing costs for the systems would be increased and a wafer processing throughput would be reduced.

Furthermore, when performing the etch-back of the SOC film through the dry-etching method, the wafer or a film on the wafer may be damaged by plasma. Furthermore, the film on the wafer may be modified by the plasma.

SUMMARY

In view of the foregoing problems, exemplary embodiments provide a substrate processing method, a substrate processing apparatus, a substrate processing system and a recording medium having recorded thereon the substrate processing method capable of removing a part of a processing target film formed on a surface of a substrate under a normal pressure atmosphere while suppressing an influence upon the substrate.

In one exemplary embodiment, a substrate processing method includes coating a source material of a processing target film, which is decomposed by irradiating an ultraviolet ray thereto under an oxygen-containing atmosphere, on a substrate; forming the processing target film by heating the source material coated on the substrate; and removing a part of the processing target film by placing the substrate having thereon the processing target film within a processing chamber under the oxygen-containing atmosphere where a gas flow velocity is equal to or smaller than 10 cm/sec, and, then, by irradiating the ultraviolet ray to the substrate.

In another exemplary embodiment, a substrate processing method includes coating a source material of a processing target film, which is decomposed by irradiating an ultraviolet ray thereto under an oxygen-containing atmosphere, on a substrate; forming the processing target film by heating the source material coated on the substrate; removing a part of the processing target film by placing the substrate having thereon the processing target film within a processing chamber provided with a gas exhaust device under the oxygen-containing atmosphere, and, then, by irradiating the ultraviolet ray to the substrate in a state where an exhaust of an inside of the processing chamber by the gas exhaust device is stopped; and exhausting the inside of the processing chamber by the gas exhaust device.

Each of the substrate processing methods includes configurations to be described below:

The substrate processing method may include generating the oxygen-containing atmosphere by supplying an oxygen-containing gas, having an oxygen concentration higher than that in the air and equal to or lower than 60 vol %, into the processing chamber before the removing of the part of the processing target film. Here, in the substrate processing method of the another exemplary embodiment, the generating of the oxygen-containing atmosphere, the removing of the part of the processing target film and the exhausting of the inside of the processing chamber may be repeatedly performed.

The substrate processing method may include supplying an exhausting gas for facilitating the exhaust of the inside of the processing chamber when performing the exhausting of the inside of the processing chamber by the gas exhaust device. The supplying of the exhausting gas may be performed when performing the exhausting of the inside of the processing chamber.

The substrate processing method may include heating the substrate while performing the removing of the part of the processing target film. The heating of the substrate may be performed such that a temperature of a peripheral portion of the substrate becomes lower than a temperature of a central portion of the substrate.

The removing of the part of the processing target film may be performed under a condition where an illuminance of the ultraviolet ray is respectively set for regions of the substrate.

The substrate processing method may include placing the substrate coated with at least the source material of the processing target film on a placing table at a transfer position, and then, moving the placing table up to a processing position; and lowering the placing table, on which the substrate from which the part of the processing target film is removed is placed, from the processing position to the transfer position, and then, carrying out the substrate. Here, an opening may be formed at a bottom surface of the processing chamber, and the placing table may be configured to be fitted into the opening and hold the substrate placed thereon, and an elevating device may be configured to move the placing table up and down between the transfer position where the substrate is transferred and the processing position which is above the transfer position and where the opening of the processing chamber is blocked and the substrate is placed within the processing chamber.

The processing target film may be an organic film containing a carbon compound.

The coating of the source material of the processing target film may be performed on the substrate having thereon a pattern. The coating of the source material of the processing target film on the substrate, the forming of the processing target film and the removing of the part of the processing target film may be performed multiple times in this sequence. Further, in the removing of the part of the processing target film performed at least before the last time, the part of the processing target film may be removed until a surface of the pattern is exposed.

In yet another exemplary embodiment, a substrate processing apparatus includes a placing table configured to hold thereon a substrate having a processing target film, which is decomposed by irradiating an ultraviolet ray thereto under an oxygen-containing atmosphere; a processing chamber, configured to accommodate therein the substrate placed on the placing table, having therein the oxygen-containing atmosphere; and an ultraviolet ray irradiation device configured to irradiate the ultraviolet ray to the substrate within the processing chamber. The placing table is provided with a surrounding member configured to surround the substrate placed on the placing table and restrict a gas introduction amount from an outside of the substrate toward above the substrate.

In still another exemplary embodiment, a substrate processing apparatus a placing table configured to hold thereon a substrate having a processing target film, which is decomposed by irradiating an ultraviolet ray thereto under an oxygen-containing atmosphere; a processing chamber, configured to accommodate therein the substrate placed on the placing table, having therein the oxygen-containing atmosphere; an ultraviolet ray irradiation device configured to irradiate the ultraviolet ray to the substrate within the processing chamber; a gas exhaust device configured to exhaust an inside of the processing chamber; and a controller configured to output a control signal such that a removing process of removing a part of the processing target film by irradiating the ultraviolet ray to the substrate from the ultraviolet ray irradiation device is performed in a state where the exhaust of the inside of the processing chamber by the gas exhaust device is stopped and then an exhausting process of exhausting the inside of the processing chamber by the gas exhaust device is performed.

According to the exemplary embodiments, since a part of the processing target film is removed by irradiating the ultraviolet ray thereto, it is possible to perform the processing under a normal pressure atmosphere while suppressing an influence upon the substrate. At this time, by irradiating the ultraviolet ray within the processing chamber in which a gas flow velocity is equal to or less than 10 cm/sec, an influence from a gas flow can be suppressed, and, thus, the partial removal of the processing target film can be carried out uniformly over a surface of the substrate.

According to the other exemplary embodiments, when irradiating the ultraviolet ray to the substrate within the processing chamber equipped with the gas exhaust device, by stopping the exhaust of the inside of the processing chamber through the gas exhaust device, the influence from the gas flow can be suppressed. Hence, the partial removal of the processing target film can be performed uniformly over the surface of the substrate.

DETAILED DESCRIPTION

Hereinafter, exemplary embodiments will be described.FIG. 1is a plan view illustrating an outline of a wafer processing system (substrate processing system)1according to a first exemplary embodiment.FIG. 2andFIG. 3are side views illustrating an outline of the inside of the wafer processing system1. The present exemplary embodiment will be described for a case where the wafer processing system1forms an organic film, which is decomposed by irradiating an ultraviolet ray thereto, as a SOC film on a surface of a wafer W serving as a substrate. Further, a pattern of a SiO2film or the like is previously formed on the surface of the wafer W to be processed in the wafer processing system1.

As depicted inFIG. 1, the wafer processing system1includes a cassette station110; and a processing station120connected thereto. In the cassette station110, carry-in/out of a cassette C accommodating a multiple number of, e.g., 25 sheets of wafers W is carried-in/out the outside thereof and, also, the wafer W is carried-in/out the cassette C. The processing station120includes a multiple number of processing apparatuses, each of which is configured to perform a preset process on the wafer W.

Below, in the description of the wafer processing system1, a direction where the cassette station110is located will be defined as a front side, and a direction where the processing station120is located will be referred to as a rear side.

The cassette station110is equipped with a cassette placing table111. The cassette placing table111is arranged in a single row along a front-side surface of the wafer processing system1. A multiple number of cassettes C can be placed on the cassette placing table111.

Provided within the cassette station110is a wafer transfer device113configured to be movable is carried-in/out on a travel path112which is extended in a left-right direction when viewed from the front side. The wafer transfer device113is configured to be also movable vertically and pivotable around the vertical axis (i.e., movable in a θ direction) and is capable of transferring the wafer W between the cassette C and the processing station120.

The processing station120has a wafer transfer device122provided at a central portion thereof. For example, four processing blocks G1to G4, each of which includes various kinds of processing apparatuses arranged in multiple levels, are provided around the wafer transfer device122. On the right side of the wafer transfer device122when viewed from the front side, a first processing block G1and a second processing block G2are arranged in this sequence from the front side. On the left side of the wafer transfer device122when viewed from the same direction, a third processing block G3and a fourth processing block G4are arranged in this sequence from the front side.

Further, a delivery table121for delivering the wafer W is provided at a front central position of the processing station120facing the cassette station110. The wafer transfer device122is capable of transferring the wafers W into/from the delivery table121and the various processing apparatuses to be described later, which are disposed in the processing blocks G1to G4.

As depicted inFIG. 2, in the first processing block G1, coating apparatuses130and131, each of which is configured to coat a source material for forming a SOC film on a wafer W, are stacked in two levels in sequence from below. Likewise, in the second processing block G2, coating apparatuses132and133are stacked in two levels in sequence from below. At the lowermost levels of the first processing block G1and the second processing block G2, chemical chambers134and135for supplying the source material of the SOC film to the coating apparatuses130to133are provided, respectively.

Here, a liquid, which is prepared by dissolving an organic film source material, for example, a polymer source material having a polyethylene structure ((—CH2—)n), containing a carbon compound to be decomposed through a reaction with active oxygen or ozone generated as a result of irradiating an ultraviolet ray in an oxygen-containing atmosphere, into a solvent may be used as the source material of the SOC film supplied from the chemical chambers134and135.

As depicted inFIG. 3, in the third processing block G3, wafer processing apparatuses140,141and142each configured to perform heat treatment or ultraviolet ray irradiation on the wafer W and temperature control apparatuses143and144each configured to adjust a temperature of the wafer W are stacked in five levels in sequence from the bottom. As in the third processing block G3, wafer processing apparatuses150,151and152and temperature control apparatuses153and154are stacked in five levels in sequence from the bottom in the fourth processing block G4.

Now, configurations of the coating apparatuses130to133will be explained. Since the coating apparatuses130to133have the same configuration, only the configuration of the coating apparatus130is illustrated inFIG. 4as an example.

The coating apparatus130has a processing vessel200, the inside of which is hermetically sealable. A carry-in/out opening (not shown) for the wafer W is each in a side surface of the processing vessel200at the side of the wafer transfer device122. A shutter (not shown) is provided at the carry-in/out opening.

A spin chuck210configured to hold and rotate the wafer W thereon is provided within the processing vessel200. A placing surface for the wafer W is formed on a top surface of the spin chuck210, and a suction hole (not shown) for suctioning the wafer W is formed on the placing surface. The wafer W can be attracted to and held on the spin chuck210by being suctioned through this suction hole.

A chuck driving device211having, for example, a motor is provided under the spin chuck210. The spin chuck210is configured to be rotated at a preset speed by the chuck driving device211. Further, the chuck driving device211is also equipped with an elevating device such as a cylinder configured to be moved up and down.

A recovery cup212for receiving and collecting a liquid dispersed or falling from the wafer W is provided around the spin chuck210. Connected to a bottom surface of the recovery cup212are a discharge line213through which the collected liquid is discharged and an exhaust line214through which an atmosphere within the recovery cup212is exhausted.

A coating nozzle222held by a nozzle head221is provided above the spin chuck210. The nozzle head221is held by an arm (not shown) which is configured to be moved along a rail (not shown) extended in the left-right direction inFIG. 4. Provided at the side of the recovery cup212is a nozzle bus224in which the nozzle222stands for a time period during which the source material onto the wafer W is not coated.

Accordingly, the coating nozzle222can be moved between the nozzle bus224as a standby position and a position above a central portion of the wafer W at which the source material is supplied onto the wafer W placed on the spin chuck210. Further, the arm holding the nozzle head221is configured to be moved up and down, so that height of the coating nozzle222can be adjusted.

A supply line225through which the source material of the SOC film is supplied to the coating nozzle222is connected to the coating nozzle222. The supply line225communicates with a source material supply source226that stores the source material therein. Further, the supply line225is provided with a flow rate controller227that stops the supply of the source material or adjusts a flow rate of the source material.

A back rinse nozzle (not shown) configured to discharge a cleaning liquid toward a rear surface of the wafer W may be provided under the spin chuck210. The rear surface of the wafer W and a peripheral portion of the wafer W may be cleaned by the cleaning liquid discharged from the back rinse nozzle.

Now, referring toFIG. 5toFIG. 8, configurations of the aforementioned wafer processing apparatuses140to142and150to152will be discussed. Since these wafer processing apparatuses140to142and150to152have the same configuration, only the configuration of the wafer processing apparatus140is illustrated inFIG. 5toFIG. 8as an example.

As shown inFIG. 5, the wafer processing apparatus140is provided with a flat housing300having a long and narrow rectangular shape elongated in the front/rear direction. A carry-in/out opening301for the wafer W and a shutter302for opening or closing the carry-in/out opening301are provided at a side wall surface of the housing300at the front side thereof.

The inside of the housing300is partitioned into an upper space and a lower space by a partition plate303. A transfer arm41configured to transfer the wafer W is provided in the upper space above the partition plate303at the front side when viewed from the carry-in/out opening301. The transfer arm41is equipped with a non-illustrated moving device that enables the transfer arm41to be moved between a front position where the wafer W is transferred between the transfer arm41and the wafer transfer device122of the wafer processing system1and a rear position where the wafer W is delivered between the transfer arm41and a placing table51to be described later. The transfer arm41also serves as a cooling arm that cools the processed wafer W.

Supporting pins421configured to support the wafer W temporarily when the wafer W is delivered between the wafer transfer device122and the transfer arm41are provided at the front position where the wafer W is delivered to/from the wafer transfer device122. The supporting pins421are connected to an elevation motor423via an elevating member422which is provided in the lower space under the partition plate303. With this configuration, the supporting pins421can be moved up and down between a position below a wafer placing surface of the transfer arm41and a position which is above this wafer placing surface and at which the wafer W is delivered to/from the wafer transfer device122.

The placing table51for the wafer W is provided at a position at the rear side of the position where the wafer W is delivered between the transfer arm41and the wafer transfer device122. As depicted in a plan view ofFIG. 6, the placing table51is formed of a rectangular plate member which is made of a ceramic material such as SiC or AlN. The placing table51has a heater512embedded therein to serve as a heating device configured to heat the wafer W. The heater512is divided in a diametrical direction of the wafer W and is configured to vary a heating temperature for individual areas of the wafer W. Detailed configuration of this heater will be elaborated later.

The placing table51is supported by a multiple number of extensible/contractible supporting members531from the rear surface thereof. By extending and contracting the supporting members531by motors532provided at base end portions of the respective supporting members531, the placing table51can be moved up and down in the vertical direction between a processing position where the wafer W is processed and a delivery position where the wafer W is delivered to/from the transfer arm41. The partition plate303is provided with a notch corresponding to the shape of the placing table51. As depicted inFIG. 8, when the placing table51is lowered, the placing table51is fitted into the notch, and the partition plate303and the placing table51are substantially arranged on the same plane.

As illustrated inFIG. 5andFIG. 8, under the placing table51are provided supporting pins541configured to support the wafer W temporarily when the wafer W is delivered between the placing table51and the transfer arm41. As shown inFIG. 6, the placing table51is provided with through holes511through which the supporting pins541are allowed to pass. When the placing table51is lowered downwards, tip end portions of the supporting pins541are protruded from a top surface of the placing table51.

The supporting pins541are connected to an elevation motor543via an elevating member542. The supporting pins541are moved up and down between a position under the wafer placing surface of the transfer arm41which is moved to a position above the placing table51and a position above this wafer placing surface, so that the wafer W can be delivered to/from the transfer arm41. Further, by moving the placing table51up and down after the transfer arm41is retreated to the front position, the wafer W is delivered between the placing table51and the supporting pins541.

An opening63having a shape corresponding to the placing table51is formed in a ceiling surface of the housing300above the placing table51. Further, a flat processing chamber61is provided on a top surface of the housing300to cover the opening63. The placing table51supported by the supporting members531can be fitted into the opening63, so that a processing space60for the wafer W can be formed between the placing table51and the processing chamber61(FIG. 5).

A height dimension between a top surface of the wafer W placed on the placing table51and a ceiling surface (a UV transmission member73to be described later) of the processing space60is in a range from several millimeters (mm) to several tens of millimeters (mm), for example, 3 mm.

In this processing space60, a process of forming a SOC film by heating the wafer W coated with the source material of the SOC film and a process of removing a part of the SOC film by irradiating an ultraviolet ray (UV light) to this SOC film are performed.

As illustrated inFIG. 5andFIG. 6, a gas introduction room621extended in the left-right direction when viewed from the front side is formed along a front-side periphery of the placing table51at a position in front of the processing space60. The gas introduction room621is connected to a clean air supply device625via an air supply line624. Clean air is supplied from the clean air supply device625to the gas introduction room621.

Further, a multiple number of gas introduction holes622are formed with a gap therebetween in a sidewall surface of the gas introduction room621that faces the processing space60. Accordingly, the clean air supplied into the gas introduction room621is uniformly introduced into the processing space60. Further, a tapered portion623provided between the gas introduction room621and the processing chamber61is configured to adjust a discharge position of the clean air from the gas introduction holes622and an introduction position of the clean air into the processing space60.

Meanwhile, a gas exhaust room641extended in the left-right direction when viewed from the front side is formed along a rear-side periphery of the placing table51at a position behind the processing space60. The gas exhaust room641is connected to a gas exhaust line644which is equipped with a gas exhaust fan645configured to exhaust an atmosphere within the processing space60. The gas exhaust line644is connected to an external harm-removing facility646.

The gas exhaust room641, the gas exhaust line644, the gas exhaust fan645, and so forth correspond to a gas exhaust device according to the present exemplary embodiment.

A multiple number of gas exhaust holes642are formed with a gap therebetween in a sidewall surface of the gas exhaust room641that faces the processing space60. The atmosphere within the processing space60is exhausted through these gas exhaust holes642. A tapered portion643provided between the processing chamber61and the gas exhaust room641is configured to adjust a discharge position of the atmosphere within the processing space60and an exhaust position from the gas exhaust holes642.

As depicted inFIG. 5andFIG. 6, as the gas introduction room621and the gas exhaust room641are arranged to be opposed to each other at the front and rear sides with the processing space60therebetween, a one-direction flow of the clean air, which flows toward the gas exhaust room641through the processing space60after supplied from the gas introduction room621, is formed within the processing space60.

A lamp chamber71which accommodates therein UV lamps72for irradiating UV rays to the wafer W placed in the processing space60is provided at an upper side of the processing chamber61. As shown inFIG. 7, each of the multiple straight tube-shaped UV lamps72is extended in the forward/backward direction, and the UV lamps72are arranged with a gap therebetween. In the present exemplary embodiment, four UV lamps72are provided.

A wavelength of the UV rays irradiated from the UV lamp72may not be particularly limited as long as the UV rays are capable of generating active oxygen or ozone for removing a SOC film from oxygen included in the atmosphere within the processing space60. As the wavelength of the UV rays decreases, energy may be increased, whereas the UV rays may become easier to be absorbed into a gas within the processing space60. In consideration of a balance between these two aspects, the UV lamps72used in the present exemplary embodiment irradiate UV rays of a wavelength of 172 nm.

These UV lamps72are connected to a power supply device74, and they are turned on as a power is supplied from this power supply device74and turned off as the power supply is stopped.

As illustrated inFIG. 5,FIG. 11and so on, the UV transmission member73that transmits the UV rays irradiated from the UV lamps72toward the inside of the processing space60is provided between the processing chamber61and the lamp chamber71which are stacked on top of each other in the vertical direction. The UV transmission member73is made of, by way of non-limiting example, a glass plate that transmits the UV rays.

The UV lamps72, the power supply device74, the UV transmission member73, and so forth correspond to an ultraviolet ray irradiation device according to the present exemplary embodiment.

The wafer processing apparatus140having the above-described configuration performs a SOC film forming process of forming the SOC film as the processing target film by heating the wafer W within the processing space60and a wafer surface planarizing process of planarizing the surface of the wafer W by removing a part of the SOC film through the irradiation of the UV rays to the wafer W, as already mentioned above.

Among these processes, the SOC film forming process is performed under a condition where the one-direction flow of the clean air that flows from the gas introduction room621to the gas exhaust room641. Accordingly, components cause from the source material of the SOC film during the heating of the wafer W can be exhausted from the processing space60.

Meanwhile, the present inventors found out that if the UV rays are irradiated to the wafer W under the condition where the one-direction flow of the clean air, i.e., the same condition as that in case of forming the SOC film, it becomes difficult to remove the SOC film uniformly, which suppresses the surface of the wafer W from being planarized.

As depicted inFIG. 9, if the UV rays are irradiated toward the processing space60in which the one-direction flow of the clean air from the gas introduction room621to the gas exhaust room641is formed, an atmosphere including abundant active oxygen or ozone is created at an upstream side in the flow direction. Further, within the flat processing chamber61, the air flow velocity becomes slower in a region close to the left and right sidewall surfaces, when viewed from the front side, than in a region on a central region. As a result, a state in which the active oxygen or ozone is abundant is created at a front side and at left and right side positions within the processing space60. Accordingly, the wafer W placed in the processing space60may have a region (film thickness decrease region R) where the film removing amount is increased, i.e., the region where the active oxygen or ozone is abundant. Resultantly, the SOC film may not be removed uniformly.

In order to solve this problem, in the wafer processing apparatus140according to the present exemplary embodiment, a circular ring-shaped surrounding member52that surrounds the wafer W placed on the placing table51is provided as shown inFIG. 5andFIG. 6, so that the gas introduction into the space above the wafer W to which the UV rays are irradiated can be suppressed. Further, during the irradiation of the UV rays, the supply of the clean air from the gas introduction room621and a compulsory exhaust from the gas exhaust room641are stopped. By irradiating the UV rays in this stationary atmosphere, it is possible to suppress the film thickness decrease region R, illustrated inFIG. 9, from being generated.

As will be elaborated later, since the convection is created within the processing space60surrounded by the surrounding member52, the gas flow velocity within the processing space60may not become zero in the present exemplary embodiment. However, if the gas flow velocity within the processing space60is equal to or less than 10 cm/s, it is possible to suppress the film thickness decrease region R from being generated, and the planarizing process of the wafer W can be performed uniformly.

Meanwhile, if the UV rays are irradiated within the narrow space surrounded by the surrounding member52even without supplying oxygen from the outside, there may be a lack of active oxygen or ozone required for removing the SOC film. To solve this problem, a gap (oxygen inlet opening601) is formed between an upper end of the surrounding member52and a ceiling surface of the processing chamber61, as shown inFIG. 11and an enlarged view ofFIG. 12. As a result, clean air including oxygen can be introduced into the space surrounded by the surrounding member52from the outside (an oxygen supply space602shown inFIG. 6and so forth) of the surrounding member52.

The height of the oxygen inlet opening601is set to be larger than zero and equal to or smaller than 3 mm, for example, 0.8 mm. Here, however, the oxygen inlet opening601may not be merely limited to the gap between the upper end of the surrounding member52and the ceiling surface of the processing chamber61. Alternatively, a slit-shaped oxygen inlet opening601may be formed along a circumferential direction of the surrounding member52, and this opening may be closed during the process by the UV rays.

In the illustration ofFIG. 11andFIG. 12, the height dimensions of the processing space60and the surrounding member52are exaggerated.

As will be presented in experimental results to be described later, the present inventors have also found out that even in case of irradiating the UV rays to the wafer W within the processing space60surrounded by the surrounding member52, a removing rate of the SOC film can also be increased by increasing a temperature of the placing table51with the heater512to heat the wafer W. Further, the present inventors have also found out that if the UV rays are irradiated while a temperature of the entire surface of the wafer W is maintained uniform, it is possible to obtain a film thickness distribution where the film removing amount becomes larger at a peripheral portion of the wafer W and becomes smaller toward a central portion of the wafer W.

The reason for the above-mentioned film thickness distribution may be because by-products, which are generated when the SOC film is decomposed, float within the processing space60and absorb the UV rays, so that the generation of active oxygen or ozone can be suppressed, and, also, because these by-products react with the active oxygen or ozone, so that the reaction of the active oxygen or ozone with the SOC film can be suppressed (FIG. 11). Further, the reason why the film removing amount at the peripheral region of the wafer W becomes larger than at the central region of the wafer W may be because an amount of the by-products generated at the peripheral region of the wafer W in the vicinity of the surrounding member52is smaller than an amount generated at the central region of the wafer W, and, also, because oxygen as a source of the active oxygen or ozone is supplied through the oxygen inlet opening601.

To solve the problem, in the wafer processing apparatus140according to the present exemplary embodiment, the placing table51is concentrically divided in the diametrical direction of the wafer W into a first placing table region (first heating device)51aand a second placing table region (second heating device)51b, as illustrated inFIG. 11. A power from a power supply device514aconfigured to supply a power to a first heater512ain the first placing table region51aprovided at a central side of the placing table51may be different from a power supply device514bconfigured to supply a power to a second heater512bin the second placing table region51bprovided at a peripheral side thereof. Further, as depicted inFIG. 11, a heat insulating member513is provided between the first placing table region51aand the second placing table region51b.

In the present exemplary embodiment, a temperature of the first placing table region51aon the central side is set to be in the range from 200° C. to 350° C., e.g., 300° C., and a temperature of the second placing table region51bis set to be in the range from 200° C. to 350° C., e.g., 250° C. Accordingly, by increasing a removing rate of the SOC film at the central portion of the wafer W, where the film removing amount becomes smaller when heating the wafer surface uniformly, the film thickness distribution of the SOC film after the irradiation of the UV rays can be uniformed.

The example shown inFIG. 11has been described for the case where the placing table51is divided into two in the diametrical direction of the wafer W. However, by dividing the placing table51into three or more, it may be possible to adjust the film thickness with higher precision.

Further, in the wafer processing apparatus140according to the exemplary embodiment, it is also possible to achieve the uniform thickness distribution of the SOC film after irradiating the UV-ray thereto by changing materials for the UV transmission member73corresponding to the irradiation regions of the wafer W.

That is, as illustrated inFIG. 7,FIG. 11and so forth, the UV transmission member73is divided into two in the diametrical direction of the wafer W: a first UV transmission member731and a second UV transmission member732. The first UV transmission member731is made of a glass plate having higher UV transmittance, whereas the second UV transmission member732is made of an opaque glass plate having a relatively lower UV transmittance.

Due to this difference in the materials, a UV ray passing through the first UV transmission member731is irradiated into the processing space60at an illuminance ranging from 30 mW/cm2to 60 mW/cm2, e.g., 40 mW/cm2, whereas a UV ray passing through the second UV transmission member732is irradiated into the processing space60at an illuminance ranging from 20 mW/cm2to 45 mW/cm2, e.g., 30 mW/cm2. As a result, a generation amount of active oxygen or ozone may become relatively smaller at the peripheral portion of the wafer W. Therefore, the thickness distribution of the SOC film after the UV-ray irradiation can be uniformed.

The first UV transmission member731and the second UV transmission member732correspond to an illuminance adjusting device in the present exemplary embodiment. Here, the UV transmission member73may be divided into three or more in the diametrical direction of the wafer W, so that the illuminance of the UV rays can be adjusted with higher precision.

The wafer processing system1, the coating apparatuses130to133, and the wafer processing apparatuses140to142and150to152having the above-described configurations are connected to a controller8. The controller8is implemented by a computer having a CPU and a memory. Recorded on the memory are programs including step (command) sets for the control of operations of the wafer processing system1, the coating apparatuses130to133and the wafer processing apparatuses140to142and150to152, i.e., for the control of operations of taking out the wafer W from the cassette C and delivering the wafer W into the coating apparatuses130to133or the wafer processing apparatuses140to142and150to152; forming the SOC film by coating and heating the source material; planarizing the surface of the wafer W by removing a part of the SOC film by the UV irradiation; and then returning the wafer W back into the cassette C. These programs may be stored on a recording medium such as, but not limited to, a hard disk, a compact disk, a magnetic optical disk, a memory card, or the like and may be installed in the computer therefrom.

Now, referring toFIG. 10toFIG. 13G, an operation of the wafer processing system1will be described.FIG. 10illustrates a state of the processing space60during the heating process for forming the SOC film.FIG. 11andFIG. 12depict a state of the processing space60during the irradiation of the UV rays.FIG. 13AtoFIG. 13Gschematically illustrate a longitudinal cross section in the vicinity of the surface of the wafer W being processed.

As illustrated inFIG. 13AtoFIG. 13G, a SiO2film, for example, is previously patterned on the surface of the wafer W to be processed in the wafer processing system1. Patterns P are densely and sparsely formed. There are a blanket region A where only patterns P are formed and a line-and-space region B where the patterns P and recesses Q are alternately formed.

If the cassette C accommodating the wafer W having thereon the patterns P is placed on the cassette placing table111, the wafer W is taken out of the cassette C by the wafer transfer device113. Then, the wafer W is transferred onto the delivery table121of the processing station120and delivered into any one of the temperature control apparatuses143,144,153and154by the wafer transfer device122. In the temperature control apparatus, a temperature of the wafer W is adjusted to be a set value.

Thereafter, the wafer W is transferred into the coating apparatus130by the wafer transfer device122. The wafer W carried in the coating apparatus130is delivered from the wafer transfer device122onto the spin chuck210to be attracted thereto and held thereon. Subsequently, the coating nozzle222which has been on standby in the nozzle bus224is moved to the position above the central portion of the wafer W and supplies the source material of the SOC film onto the wafer W being rotated by the spin chuck210. The source material supplied onto the wafer W being rotated is dispersed on the entire surface of the wafer W in a film shape by a centrifugal force.

At this time, as depicted inFIG. 13A, as for the source material L coated on the wafer W with a surface tension or a viscosity, the source material L (hereinafter, referred to as “source material LB”) coated on the line-and-space region B becomes recessed downwards as compared to the source material L (hereinafter, referred to as “source material LA”) coated on the blanket region A. That is, a height HB1from the tip end portions of the patterns P to a surface of the source material LBis smaller than a height HA1from the tip end portions of the patterns P to a surface of the source material LA. As a result, a step-shaped portion D1is formed between the source material LAand the source material LB.

Thereafter, the wafer W is carried out of any one of the coating apparatuses130to133by the wafer transfer device122and transferred into any one of the wafer processing apparatuses140to142,150to152(hereinafter, the reference number of the wafer processing apparatus140will only be specified for the simplicity of illustration). When the wafer transfer device122enters the wafer processing apparatus140through the carry-in/out opening301, the transfer arm41is moved to the front position and the placing table51stands by in a state where the placing table51is lowered downwards.

After the shutter302is opened, the wafer transfer device122enters the wafer processing apparatus140through the carry-in/out opening301and stops at a position above the transfer arm41. Then, the supporting pins421are lifted up and receive the wafer W from the wafer transfer device122. Afterwards, the wafer transfer device122is retreated out of the wafer processing apparatus140, and the shutter302is closed.

If the supporting pins421supporting the wafer W thereon are lowered down, the wafer W is delivered onto the transfer arm41from the supporting pins421, and the transfer arm41is moved towards the rear side where the placing table51stands by. If the transfer arm41stops at a position above the placing table51, the supporting pins541are raised up, and the wafer W is delivered onto the supporting pins541from the transfer arm41(seeFIG. 8).

Thereafter, the transfer arm41is moved to the standby position at the front side, and the placing table51is raised up to receive the wafer W from the supporting pins541. As a result, the wafer W is placed on the placing table51surrounded by the surrounding member52. The placing table51holding the wafer W thereon is moved up to a position at a bottom side of the processing chamber61to close the opening63.

Here, as illustrated inFIG. 11, if the placing table51is raised up to a position where the gap between the upper end of the surrounding member52and the ceiling surface of the processing chamber61is 0.8 mm, a uniform one-direction flow of clean air is difficult to form above the wafer W surrounded by the surrounding member52. To solve the problem, as depicted inFIG. 10, the lifting of the placing table51is stopped at the timing, for example, when the upper end of the surrounding member52and the upper ends of the tapered portions623and643are substantially arranged on the same plane.

Accordingly, the one-direction flow of the clean air flowing from the gas introduction room621toward the gas exhaust room641is formed within the processing space60formed between the processing chamber61and the placing table51. The power supply device514(514aand514b) supplies a power to the heater512(512aand512b), so that the wafer W is heated to, for example, 300° C. At this time, the outputs of the power supply devices514aand514bare same, and, thus, the entire surface of the wafer W is heated to have the same temperature.

After the wafer W is heated for a predetermined time period, a SOC film F as an organic film is formed from the source material L (FIG. 13B). Even at this time, the aforementioned step-shaped portion D1is formed between the SOC film F (hereinafter, referred to as “SOC film FA”) on the region A and the SOC film F (hereinafter, referred to as “SOC film FB”) on the region B.

By-products generated when the SOC film is formed are carried on the one-direction flow of the clean air to be exhausted from the processing space60through the gas exhaust room641(FIG. 10).

Subsequently, the supply of the clean air from the gas introduction room621and the exhaust of the inside of the processing space60by the gas exhaust room641are stopped, and the placing table51is moved up to a position where the oxygen inlet opening601between the upper end of the surrounding member52and the ceiling surface of the processing chamber61has a height of 0.8 mm (FIG. 11). Further, the output of the power supply device514bis reduced, and the heating temperature of the wafer W on the second placing table region51bis adjusted to 250° C.

Thereafter, a power is fed from the power supply device74, and each of the UV lamps72is turned on and irradiates the UV rays into the processing space60. Active oxygen or ozone is generated from oxygen in the clean air (oxygen-containing atmosphere) within the processing space60by the irradiated UV rays. A surface of the SOC film F (a part of the SOC film F) is decomposed to be removed by the active oxygen and ozone, and a so-called etch-back is performed.

At this time, the exhaust of the inside of the processing space60is stopped, and the UV rays are irradiated into the processing space60surrounded by the surrounding member52. Thus, since the SOC film is partially removed under an atmosphere where a gas flow velocity is equal to or less than 10 cm/sec, the uniform process can be performed on the entire surface of the wafer W. Further, the placing table51on which the wafer W is placed is heated by the heater512, whereas the ceiling surface of the processing space60is not heated to such a high temperature ranging from 250° C. to 300° C. As a result, a temperature distribution in which a gas temperature decreases as it goes upwards toward an upper portion of the processing space60from a lower portion thereof is generated, so that a convection where the gas is circulated above the wafer W in a vertical direction is also generated, as shown inFIG. 12. Thus, the gas within the processing chamber60is uniformly circulated. This convection also allows the uniform process to be performed on the entire surface of the wafer W.

Further, since the surrounding member52is provided with the oxygen inlet opening601, if the active oxygen or ozone is consumed within the processing space60surrounded by the surrounding member52and, thus, a concentration of these active components is reduced, an atmosphere containing oxygen (which may exist as active oxygen or ozone by being irradiated by the UV rays) is introduced into a region inside the surrounding member52. That is, a space outside the surrounding member52serves as a so-called oxygen supplement space and thus contributes to the process of removing a part of the SOC film.

At the peripheral portion of the wafer W, a temperature of the second placing table region51bis adjusted to a temperature lower than that of the first placing table region51a, and a UV-ray transmittance of the second UV transmission member732is lower than that of the first UV transmission member731at the central side thereof. Accordingly, since a removing rate of the SOC film at the peripheral region of the wafer W, which is less affected by the by-products, is suppressed to be low, the partial removal of the SOC film can be performed uniformly over the entire surface.

By irradiating the UV-rays as above-described, the SOC film of the height HA1is removed up to a depth where the SOC film FAon the region A is completely removed. As a result, surfaces of the patterns P of the wafer W are exposed, and the SOC film FAno more exists on the region A, and the SOC film FBof a height HC1remains within the recesses Q of the patterns P.

After the irradiation of the UV rays is performed for a preset time period, the UV lamps72are turned off and the power supply to the heater512is stopped, and the placing table51is lowered to a position indicated inFIG. 10. Thereafter, the one-direction flow of the clean air is formed within the processing space60again by performing the supply of the clean air from the gas introduction room621and the exhaust from the gas exhaust room641, and the active oxygen or ozone, the by-products, and so forth are exhausted from the processing space60.

Afterwards, the placing table51is moved down, and the processed wafer W is delivered onto the transfer arm41in the reverse order to that taken when loading the wafer W. The transfer arm41that has received the wafer W is moved to the front position where the wafer W is delivered to/from the wafer transfer device122and stands by for a predetermined time period and waits for the wafer W to be cooled to a preset temperature. The temperature-adjusted wafer W is delivered onto the wafer transfer device122in the reverse order to that taken when loading the wafer W and taken out of the wafer processing apparatus140.

The source material coating process by the coating apparatuses130to133, the heating process for the wafer W in the wafer processing apparatuses140to142and150to152, and the UV-ray irradiation process are performed multiple times, for example, n times in this sequence.

For example, in a second source material coating process, the source material L of the SOC film is coated again on the wafer W in any one of the coating apparatuses130to133.

In the second source material coating process, a film thickness of the source material L is controlled to be smaller than that in the first source material coating process. To elaborate, a method of increasing a rotational speed of the spin chuck210or a method of reducing a supply amount of the source material L onto the wafer W may be adopted, for example. As a result, as depicted inFIG. 13D, heights HA2and HB2of SOC films FAand FB(source materials LAand LB) in the second source material coating process become smaller than the heights HA1and HB1of the SOC films FAand FBin the first source material coating process, respectively.

Afterwards, the source material L on the wafer W is heated within the processing space60of the wafer processing apparatus140, so that a SOC film F is formed (FIG. 13D). At this time, a step-shaped portion D2formed between the SOC film FAand the SOC film FBis smaller than the step-shaped portion D1in the first source material coating process.

Then, by irradiating the UV rays onto the wafer W within the processing space60of the wafer processing apparatus141, the SOC film F of the height HA2is removed to a depth where the SOC film FAon the region A is completely removed, as shown inFIG. 13E. As a result, SOC film FAno more exists on the region A, and the SOC film FBof a height HC2remains in the recesses Q of the patterns P on the region B. The height HC2of the SOC film FBremaining after the second UV-ray irradiation becomes larger than the height HC1of the SOC film FBremaining after the first UV-ray irradiation. That is, whenever the series of processing sequences (i.e., coating the source material→forming the SOC film→removing a part of the SOC film) are repeated, the SOC film FBis deposited within the recesses Q of the patterns P.

Just like the series of processing sequences of the second processing described→above, a series of processing sequences (i.e., coating the source material→forming the SOC film removing a part of the SOC film) are also repeated in a third to a nthprocessing. As a result, step-shaped portions D3to Dnbetween the SOC film FAand the SOC film FBare gradually reduced, and a step-shaped portion Dnfinally becomes almost zero. Then, as depicted inFIG. 13F, the height of the surface of the SOC film FBequals to the height of the surface of the patterns P. Here, the step-shaped portion Dnmay not necessarily be zero but it only needs to be in a required preset range.

Thereafter, the source material L is coated on the wafer W in a preset film thickness in any one of the coating apparatuses130to133, and only the heating process of heating the source material L on the wafer W is performed within the processing space60of the wafer processing apparatus140. As a result, as shown inFIG. 13G, a SOC film F having a predetermined thickness and a planarized surface is finally formed on the wafer W.

Once the SOC film F is formed as shown inFIG. 13G, the wafer W is delivered to the transfer arm41without performing the UV-ray irradiation thereto. Then, after the temperature adjustment is performed, the wafer W is carried out of the wafer processing apparatus140by the wafer transfer device122. Thereafter, the wafer W is transferred into the cassette station110from the processing station120via the delivery table121and the wafer transfer device113in sequence and returned back into the cassette C on the cassette placing table111. Then, the SOC film forming process for planarizing the surface of the wafer W in the wafer processing system1is completed.

With the wafer processing system1and the wafer processing apparatuses140to142and150to152according to the present exemplary embodiment, the following effects can be achieved. Since a part of the SOC film is removed by irradiating UV rays thereto, the removal can be performed under a normal pressure atmosphere while suppressing an influence upon the wafer W. At this time, the UV-ray irradiation is performed in the processing chamber61having the exhaust device (the gas exhaust room641, the gas exhaust fan645, or the like) under the conditions where the exhaust of the inside (processing space60) of the processing chamber61is stopped and the gas flow velocity is equal to or less than 10 cm/sec. Accordingly, the partial removal of the SOC film can be carried out uniformly on the surface of the wafer W while suppressing an influence caused by the gas flow.

Now, referring toFIG. 14toFIG. 16, a wafer processing apparatus140aaccording to a second exemplary embodiment will be discussed. In the wafer processing apparatus140a, a gas introduction room621for supplying an oxygen-containing gas into a processing space60and a gas exhaust room641for discharging a gas exhausted form the processing space60are provided below the placing table51. In this aspect, the second exemplary embodiment is different from the first exemplary embodiment in which the gas introduction room621, the gas exhaust room641and the processing space60are arranged horizontally (seeFIG. 5andFIG. 10).

Further, in each of various exemplary embodiments to be described with reference toFIG. 14toFIG. 18E, constituent components having the same functions as those of the wafer processing apparatus140of the first exemplary embodiment will be assigned the same reference numerals as depicted inFIG. 5toFIG. 12. Further, inFIG. 14toFIG. 18E, illustration of divisions (a first and a second UV transmission member731and732) of a UV transmission member73and divisions (a first and a second placing table region51aand51b) of the placing table51are omitted.

As illustrated inFIG. 14toFIG. 16, the placing table51of the wafer processing apparatus140aaccording to the present exemplary embodiment is provided with a cylindrical flange640that surrounds a side peripheral surface of the placing table51. A lower end of the flange640is extended downwards. The flange640is fixed to the placing table51to be moved in a vertical direction together with the placing table51as the supporting members531are extended and contracted.

As shown inFIG. 16, provided within the flange640at the rear side when viewed from the placing table51is a gas introduction room621which is formed as an arc-shaped groove along the placing table51. As depicted inFIG. 14, the gas introduction room621is connected with an air supply line624, and clean air as an oxygen-containing gas is supplied from a clean air supply device625. In the wafer processing apparatus140aaccording to this second exemplary embodiment, the clean air is force-fed by using an air pump626provided on the air supply line624. Further, the air supply line624provided within a housing300ais made of a flexible hose or the like to be transformed according to the vertical movement of the flange640.

A top surface of the gas introduction room621is covered with a top surface member of the flange640, and the top surface member covering the gas introduction room621is provided with a multiple number of gas introduction holes622along the circumference of the placing table51. The clean air diffused within the gas introduction room621is discharged from the gas introduction holes622in a dispersed manner (FIG. 16). As shown inFIG. 14, the gas introduction holes622are formed at a height position lower than the processing space60(i.e., lower than the wafer W placed on the placing table51) that accommodates the wafer W therein.

Meanwhile, provided within the flange640at the front side when viewed from the placing table51is provided a gas exhaust room641which is formed as an arc-shaped groove along the placing table51. (FIG. 16). As depicted inFIG. 14, the gas exhaust room641is connected with a gas exhaust line644, and a gas exhausted from the processing space60is introduced into the gas exhaust room641and then is discharged to an external harm-removing facility646. Further, the gas exhaust line644is also made of a flexible hose or the like such that it may be transformed according to the vertical movement of the flange640. Instead of or together with the force-feeding of the clean air using the air pump626provided on the side of the air supply line624, a gas exhaust by a gas exhaust fan645provided on the side of the gas exhaust line644may be performed.

Further, a top surface of the gas exhaust room641is covered with the top surface member of the flange640, and the top surface member covering the gas exhaust room641is provided with a multiple number of gas exhaust holes642along the circumference of the placing table51. A gas exhausted from the gas introduction room621is discharged into the gas exhaust room641through the gas exhaust holes642(FIG. 16). As shown inFIG. 14, the gas exhaust holes642are also formed at a height position lower than the processing space60(i.e., lower than the wafer W placed on the placing table51).

Further, within the flange640, the gas introduction room621and the gas exhaust room641are distanced apart from each other such that the clean air supplied into the gas introduction room621is not directly introduced into the gas exhaust room641.

A circular ring-shaped lower-side flow path forming member652having a protruded and curved surface, which is bent from a peripheral portion of the placing table51toward a surrounding member52aprovided on the placing table51, is provided on an upper end portion of the flange640. Meanwhile, an upper-side flow path forming member651having an opening63(seeFIG. 15), which conforms to the placing table51and the flange640, is provided at a ceiling surface of a housing300a. The upper-side flow path forming member651is provided with a recessed and curved surface, which is formed along the circumference of the opening63.

At the regions where the gas introduction holes622and the gas exhaust holes642are formed, the recessed curved surface of the upper-side flow path forming member651is disposed to face the protruded and curved surface of the lower-side flow path forming member652with a gap of several millimeters (mm) apart from the protruded and curved surface of the lower-side flow path forming member652when the placing table51is raised up to the processing position. As shown inFIG. 14, gaps surrounded by the opposing curved surfaces of the upper and lower-side flow path forming members651and652serves as slit-shaped flow paths653aand653bthrough which the clean air supplied into the processing space60and the gas exhausted from the processing space60are flown, respectively. In the wafer processing apparatus140aaccording to the this second exemplary embedment, a flat circular plate-shaped space surrounded by the upper-side flow path forming member651, the placing table51and the ceiling surface (UV transmission member73) of the housing300aserves as the processing space60. Accordingly, in a region outside a surrounding member52a, the oxygen supply space602as depicted inFIG. 6and so forth is not formed.

Meanwhile, at a the remaining region where the gas introduction holes622and the gas exhaust holes642are not formed, by allowing the curved surfaces of the upper-side and lower-side flow path forming members651and652to be located as closely to each other as possible, a gas flow path may not be formed therebetween. Thus, the clean air supplied from the gas introduction holes622may not flow into the gas exhaust holes642by bypassing the processing space60.

In the wafer processing apparatus140ahaving the above-described configuration, if the placing table51is moved up to the processing position, the processing space60is formed between the UV transmission member73and the placing table51, and the flow path653afor the supply of the clean air and the flow path653bfor the exhaust of the gas from the processing space60are formed between the lower-side flow path forming member652and the upper-side flow path forming member651. If the clean air is supplied into the gas introduction room621from the air supply line624, the clean air is introduced into the processing space60via the flow path653a, so that an oxygen-containing atmosphere is created within the processing space60. A gas substituted with the clean air within the processing space60flows to form the one-direction flow, and then, is exhausted via the flow path653band discharged toward the downstream of the gas exhaust room641through the gas exhaust holes642.

Here, in the wafer processing apparatus140aof the second exemplary embodiment, the gap between the upper end of the surrounding member52aand the ceiling surface of the processing space61is set to have a size that allows the air sent by the air pump626to flow toward the gas exhaust room641through the gas exhaust holes642and that allows a one-direction air flow within the processing space60.

The constitution that the wafer W is heated by a heater512in this state, the SOC film F is formed on the surface of the wafer W coated with the source material L and by-products generated at that moment is exhausted through the gas exhaust holes642from the inside of the processing space60are the same as those of the wafer processing apparatus140according to the first exemplary embodiment as described above with reference toFIG. 10.

Also, as in the wafer processing apparatus140according to the first exemplary embodiment, the supply of the clean air through the gas introduction holes622and the exhaust of the inside of the processing space60through the gas exhaust holes642are stopped at the timing when the SOC film F is formed; ozone or active oxygen are generated within the processing space60by turning on the UV lamps72; a part of the SOC film F is removed (seeFIG. 11); the inside of the processing space60is exhausted by forming the one-direction flow of the gas flowing from the gas introduction holes622toward the gas exhaust holes642after removing the part of the SOC film F.

In the wafer processing apparatus140aaccording to the second exemplary embodiment illustrated inFIG. 14toFIG. 16, the gas introduction room621for supplying the clean air into the processing space60is located below the processing space60, and the gas exhaust room641through which the gas exhausted from the processing space60is discharged is also provided below the processing space60. Accordingly, an air supply device (the flange640in a region where the gas introduction room621is provided, the air supply line624, and so forth) for the supply of the clean air and a gas exhaust device (the flange640in a region where the gas exhaust room641is formed, the gas exhaust line644, and so forth) for the exhaust of the gas within the processing space60can be provided by using a space within the housing300aconstituting the wafer processing apparatus140a. Thus, the wafer processing apparatus140acan be reduced in size as compared to the wafer processing apparatus140of the first exemplary embodiment where the gas introduction room621, the gas exhaust room641and the processing space60are arranged horizontally.

In addition, the scale-down of the wafer processing apparatus140aof the second exemplary embodiment can also be achieved by the following configurations. That is, the transfer arm41serving as a cooling arm may not be provided, and the wafer W may be directly delivered between the supporting pins541and the wafer transfer device122that has entered through the carry-in/out opening301. Further, the supporting pins541are supported at a certain height position by a base543and are configured not to be moved up and down. Besides, a height dimension of the housing300ais also decreased.

Now, referring toFIG. 17andFIG. 18AtoFIG. 18E, a wafer processing apparatus140baccording to a third exemplary embodiment will be described.

As stated above, in the wafer processing apparatus140aaccording to the second exemplary embodiment, the oxygen supply space602, which is provided in the wafer processing apparatus140of the first exemplary embodiment, is not provided in order to scale down the apparatus and so forth. In such a case, however, when the UV rays are irradiated to the oxygen-containing atmosphere within the narrow processing space60without supplying the clean air, the concentration of the active oxygen or ozone would be reduced as the SOC film is moved, so that the removing rate of the SOC film may be decreased.

To solve the problem, in the wafer processing apparatus140baccording to the third exemplary embodiment, a high-concentration oxygen supply device626aconfigured to supply “high-concentration oxygen” into the processing space60is connected to the processing space60, as depicted inFIG. 17. By increasing the amount of oxygen included in the oxygen-containing atmosphere, a requirement amount of the active oxygen or ozone for the removal of the SOC film can be obtained.

Further, in the wafer processing apparatus140bshown inFIG. 17andFIG. 18AtoFIG. 18E, no surrounding member52or52ais provided on the placing table51.

In the preset exemplary embodiment, the term “high-concentration oxygen” refers to an oxygen-containing gas having an oxygen concentration higher than 21 vol % (in a normal state of 0° C. and 1 atmosphere) and equal to or lower than 60 vol %, more desirably, in the range from 25 vol % to 60 vol %. By way of example, the high-concentration oxygen may be prepared by mixing an oxygen gas into the clean air.

The high-concentration oxygen supply device626ais connected to the processing space60of the wafer processing apparatus140bshown inFIG. 17, and the high-concentration oxygen is supplied into the processing space60from a gas introduction hole622a. The supply of the high-concentration oxygen into the processing space60is stopped by a pneumatic value628a. Here, when preparing the high-concentration oxygen by mixing oxygen obtained by vaporizing liquid oxygen with clean air, for example, a temperature of the high-concentration oxygen may be decreased due to heat of vaporization at the time of vaporizing the liquid oxygen. Thus, in order to suppress the temperature of the processing space60from being decreased, a heating device627configured to heat the high-concentration oxygen is provided on an air supply line624a.

Further, in the wafer processing apparatus140b, a clean air supply device626bconfigured to supply the clean air into the processing space60as an example exhausting gas for exhausting a gas within the processing space60is connected to the wafer processing apparatus140b. The clean air is supplied into the processing space60from the clean air supply device626bthrough an air supply line624bconnected to a gas introduction hole622b, and the supply of the clean air into the processing space60is stopped by a pneumatic valve628b. Further, the clean air supplied from the clean air supply device626bis also used for forming the SOC film F as described above with reference toFIG. 10,FIG. 14, and so on. The clean air supply device626bthat supplies the clean air as the exhausting gas corresponds to an exhausting gas supply device of the present exemplary embodiment.

In addition, as depicted inFIG. 17, a start and a stop of the exhaust of the gas within the processing space60through a gas exhaust line644from a gas exhaust hole642are performed by a pneumatic valve647. Operations of the aforementioned pneumatic valves628a,628band647are controlled by supplying or stopping the supply of air for operation into the pneumatic valves628a,628band647individually in response to control signals outputted from the controller8.

Now, operations of the wafer processing apparatus140baccording to the third exemplary embodiment will be explained with reference toFIG. 18AtoFIG. 18E.

If a wafer W to be processed is placed on the placing table51, the placing table51is moved upwards, and the processing space60is formed (FIG. 18A). Then, clean air is supplied into the processing space60from the clean air supply device626b, and, in the meantime, a gas exhaust from the gas exhaust hole642is performed, so that a one-direction flow of the clean air is formed within the processing space60. Since a subsequent process of forming a SOC film F on the wafer W by heating the wafer W is the same as that of the wafer processing apparatuses140and140aaccording to the first and second exemplary embodiments, redundant description thereof will be omitted here.

Upon the formation of the SOC film F, the gas supplied into the processing space60is substituted with the high-concentration oxygen from the clean air, so that an atmosphere containing the high-concentration oxygen is generated within the processing space60(FIG. 18B). At this time, the exhaust of the inside of the processing space60through the gas exhaust hole642may continue to accelerate the substitution of the gas within the processing space60.

Subsequently, the supply of the high-concentration oxygen and the exhaust of the inside of the processing space60are stopped at a timing when the inside of the processing space60has turned into the oxygen-containing atmosphere of a predetermined oxygen concentration. Then, ozone or active oxygen are generated within the processing space60by turning on the UV lamps72, and a process of removing a part of the SOC film F is performed (FIG. 18C).

At a timing when a concentration of the ozone or active oxygen within the processing space60becomes lower than a previously set target concentration as they are consumed, the UV lamps72are turned off, and the exhaust of the inside of the processing space60is performed while supplying the clean air as the exhausting gas into the processing space60(FIG. 18D). Upon the completion of the exhaust of the processing space60, the supplied gas is changed into the high-concentration oxygen, and the oxygen-containing atmosphere is generated again in the processing space60.

The above-described operations set forth inFIG. 18BtoFIG. 18Dare repeated plural times, for example, more than twice. If these operations are repeated the preset number of times, the placing table51is then lowered, and the wafer W is carried out of the wafer processing apparatus140b(FIG. 18E).

In the wafer processing apparatus140baccording to the third exemplary embodiment, the oxygen-containing atmosphere can be generated by supplying the high-concentration oxygen, and the gas within the processing space60can be substituted to generate a new oxygen-containing atmosphere at the timing when the ozone or active oxygen are consumed. Accordingly, a decrease of the removing rate of the SOC film F can be suppressed, and it is possible to remove a desired amount of SOC film F in a comparatively short time period.

Further, the removal of the SOC film F by using the high-concentration oxygen can also be performed in the wafer processing apparatus140equipped with the surrounding member52and the oxygen supply space602according to the first exemplary embodiment. In addition, in case of removing a part of the SOC film simply by using the clean air without supplying the high-concentration oxygen as well, a gas within the processing space60may be substituted by repeatedly performing the operations ofFIG. 18BtoFIG. 18D.

In the wafer processing apparatuses140,140aand140baccording to the above-described exemplary embodiments, it is not essentially necessary to provide the surrounding member52within the processing chamber61(refer to the wafer processing apparatus140baccording to the third exemplary embodiment). For example, the wafer W may be placed on the placing table51not provided with the surrounding member52, and after forming the processing space60, the UV rays may be irradiated in the state where the supply of the clean air into the processing space60and the exhaust of the inside of the processing space60are stopped. By irradiating the UV rays under the condition that the concentration of the active oxygen or ozone is not imbalanced as described with reference toFIG. 9, the SOC film can be more uniformly removed over the surface of the wafer W.

Further, in the wafer processing apparatuses140,140aand140bshown inFIG. 5and so forth, the heating process for the wafer W in order to form the SOC film and the UV-ray irradiation process for removing a part of the SOC film are performed in the common processing space60by using the same placing table51. However, these processes may be performed on individual placing tables51(heating devices) or processing spaces60.

The configuration of the processing chamber61is not limited to the aforementioned example where the opening63is formed at the bottom surface of the processing chamber61and the placing table51blocks the opening63to form the processing chamber61. For example, the wafer W may be carried in and out through the side surface of the flat processing chamber.

Further, it is not essentially necessary, either, to vary a heating temperature in a diametrical direction of the wafer W by dividing the placing table51into the first placing table region51aand the second placing table region51b, or to vary an illuminance of the UV rays in the diametrical direction of the wafer W by dividing the UV transmission member73into the first UV transmission member731and the second UV transmission member732.

Further, the temperature control of the wafer W with the transfer arm41may be performed in other temperature control apparatuses143,144,153and154, or may not be performed by lowering the heating temperature for the wafer W during the UV-ray irradiation. As will be depicted in an example to be described later, if the heating temperature for the wafer W is set to be low, the removing rate of the SOC film may be decreased. However, if there is no limit in the processing time, the UV-ray may be irradiated at a room temperature.

Further, in the process of removing a part of the SOC film for the purpose of planarizing the surface of the wafer W, there has been described a method of removing the SOC film uniformly over the surface of the wafer W by irradiating the UV rays in the state that the gas flow velocity is equal to or less than 10 cm/sec or the exhaust of the inside of the processing space60is stopped. This method of removing a part of a film from the surface of the wafer W may not limited to the partial removal of the SOC film. By way of example, this method may also be applicable to a partial removal of another coating film.

EXPERIMENTAL EXAMPLES

Within the sealed processing chamber61(processing space60), a change in a removing rate of a SOC film with a lapse of time is observed by varying a temperature of the placing table51on which a wafer W is heated.

A. Conditions for the Experiment

(Experimental example 1-1) A wafer W having thereon an organic film is placed on the placing table51in which a temperature of the entire surface thereof is set to 300° C. While irradiating the UV rays having a wavelength of 172 nm with an illuminance of 40 mW/cm2, a processing time is varied to 5 minutes, 10 minutes, 20 minutes, 30 minutes and 60 minutes. A gap between a top surface of the wafer W and a bottom surface of the UV transmission member73is 3 mm.

(Experimental example 1-2) Except that a set temperature of the placing table51is 250° C., the wafer W is processed under the same conditions as those in experimental example 1-1.

(Experimental example 1-3) Except that a set temperature of the placing table51is 200° C., the wafer W is processed under the same conditions as those in experimental example 1-1.

B. Experimental Results

Results of the experimental examples 1-1 to 1-3 are shown inFIG. 19. A horizontal axis onFIG. 19represents the processing time (min) and a vertical axis denotes the removing rate (nm/min) of the organic film. A result of the experimental example 1-1 is indicated by ∘; a result of the experimental example 1-2, Δ; and a result of the experimental example 1-3, □.

As can be seen from the results shown inFIG. 19, as the temperature of the placing table51increases, the removing rate of the organic film also increases. Meanwhile, in the experimental example 1-1 in which the temperature of the placing table51is set to 300° C., the removing rate of the organic film (an average value within each processing time) is found to decrease as the processing time increases. In the experimental example 1-2 in which the temperature of the placing table51is set to 250° C., there is also found the same tendency in the experimental example 1-1 that the removing rate of the organic film decrease as the processing time increases. In the experimental example 1-2, however, the decrease rate of the removing rate is slow than that in the experimental example 1-1. Further, in the experimental example 1-3 where the temperature of the placing table51is set to 200° C., the decrease of the removing rate of the organic film is not observed.

As described above, for the reason why the decrease of the removing rate takes place with the lapse of the processing time when the temperature of the placing table51is set to a high temperature, it is considered that with the rise of the temperature of the wafer W when the UV rays are irradiated thereto, decomposition of the organic film proceeds faster and the oxygen within the processing space60is consumed faster. Further, it is also considered that with the progress of the decomposition of the organic film, by-products are accumulated within the processing space60, so that the reaction of generating the active oxygen or ozone from the oxygen by the UV-ray irradiation is suppressed, or an influence of a reaction between the active oxygen generated from the oxygen and the by-products becomes conspicuous.

In this aspect, as explained with reference toFIG. 11, the configuration where the outside of the surrounding member52is used as the oxygen supplement space may have an effect of suppressing the decrease of the removing rate of the organic film. Further, even if the removing rate of the organic film is reduced, there would be no problem in processing the wafer W as long as a certain amount of the organic film can be removed within a previously set time period.

Within the sealed processing chamber61(processing space60), a removing rate distribution over an entire surface of an organic film is measured when the wafer W is processed while varying the illuminance of the UV rays or the temperature of the placing table51.

A. Conditions for the Experiment

(Experimental example 2-1) The wafer W is processed for one minute under the same conditions as those of the experimental example 1-3 (the temperature of the placing table51is 200° C., and the illuminance of the UV rays is 40 mW/cm2).

(Experimental example 2-2) Except that the illuminance of the UV rays is set to 60 mW/cm2, the wafer W is processed under the same conditions as those of the experimental example 2-1.

(Experimental example 2-3) Except that the temperature of the placing table51is set to 300° C. and the illuminance of the UV rays is set to 60 mW/cm2, the wafer W is processed under the same conditions as those of the experimental example 2-1.

B. Experimental Results

Results of the experimental examples 2-1 to 2-3 are shown inFIG. 20toFIG. 22. In each figure, a circle indicates an outline of the wafer W, and a horizontal axis and a vertical axis are axes of coordinates that represent a distance from a center of the wafer W.

An average value of the removing rate over the entire surface of the organic film is found to be 16.9 nm/min in the experimental example 2-1, 20.5 nm/min in the experimental example 2-2, and 36.6 nm in the experimental example 2-3. As can be seen from this result, with the increase of the illuminance of the UV rays and, also, with the rise of the temperature of the placing table51, the removing rate of the organic film also increases.

Meanwhile, in comparison ofFIG. 20toFIG. 22, in the experimental example 2-3 where the temperature of the placing table51is 300° C., the removing rate of the organic film is observed to increase from a central portion of the wafer W toward a peripheral portion thereof, whereas the uniformity of the removing rate over the entire surface thereof is deteriorated, as compared to the experimental examples 2-1 and 2-2 where the temperature of the placing table51is 200° C. This may be caused, as explained before with reference toFIG. 11, by a distribution of the by-products that are generated by the irradiation of the UV rays. In this aspect, a method of decreasing a temperature of the peripheral portion of the wafer W by generating a temperature difference between the first placing table region51aand the second placing table region51b, or a method of decreasing the illuminance of the UV rays irradiated to the peripheral portion of the wafer W by generating a difference in the UV-ray transmittance between the first UV transmission member731and the second UV transmission member732is considered as an effective way to process the surface of the wafer W uniformly.