Substrate cleaning apparatus and substrate cleaning method

A substrate cleaning apparatus (50) that cleans a substrate (S) includes: circumference supporting members (51) that support and rotate the substrate (S); a sponge (541) having a cleaning surface that is brought into contact with the surface to be cleaned of the substrate (S) being rotated by the circumference supporting members (51), and cleans the surface to be cleaned; an arm (53) that moves the sponge (541) in a radial direction of the substrate (S) while maintaining the cleaning surface in contact with the surface to be cleaned; and a controller (60) that controls the contact pressure of the cleaning surface on the surface to be cleaned. When the sponge (541) is located near the edge of the substrate (S), the controller (60) adjusts the contact pressure to a smaller value than that of when the sponge (541) is located near the center of the substrate (S).

CROSS-REFERENCE TO RELATED APPLICATIONS

The present disclosure is a 371 U.S. National Stage Application of Patent Application No. PCT/JP2015/005279 filed on Oct. 20, 2015, which claims the benefit of priority from Japanese Patent Application No. 2014-223715, filed on Oct. 31, 2014, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present technology relates to substrate cleaning apparatuses and substrate cleaning methods for cleaning substrates such as semiconductor wafers, and more particularly, to a substrate cleaning apparatus and a substrate cleaning method for cleaning the surface of a substrate while moving a cleaning head in a radial direction of the substrate.

BACKGROUND ART

As semiconductor devices have become smaller in size, substrates with microstructures (substrates formed with material films that vary in physical properties) are being processed these days. For example, in a damascene interconnect formation process in which wiring grooves formed in a substrate are filled with metal, extra metal is removed by polishing performed by a substrate polishing system (CMP system) after the damascene interconnect formation, and thus, materials films (such as a metal film, a barrier film, and an insulating film) that vary in physical properties are formed on the substrate surface. On such a substrate surface, there are residues of the slurry used in CMP and metal grinding sludge (such as Cu grinding sludge). Therefore, in a case where a substrate surface cannot be sufficiently cleaned, such as a case where complexity of a substrate surface makes the cleaning difficult, leakage or an adhesion defect occurs due to residues or the like, and might result in a decrease in reliability. To counter this, a CMP system that polishes semiconductor substrates conducts cleaning after the polishing. In the cleaning process, pen scrub cleaning or two-fluid jet cleaning is performed, for example (see Patent Literatures 1 and 2, for example).

CITATION LIST

Patent Literatures

Patent Literature 1: JP 2013-172019 A

Patent Literature 2: JP 11-40530 A

SUMMARY OF INVENTION

Problem to be Solved

In a conventional substrate cleaning apparatus, when a substrate surface is subjected to pen scrub cleaning, the substrate is rotated, and a cleaning head formed with a rotating sponge moves on the substrate surface in a radial direction of the substrate. Substrate cleaning is then conducted.FIG. 12is a plan view and a front view of a cleaning head at radial positions on a substrate.FIG. 12shows a cleaning head H1located near the center of a substrate S, a cleaning head H2located between the center and the edge of the substrate, and a cleaning head H3located near the edge of the substrate S.

As the substrate S is supported at the edge, the central portion of the substrate S sinks due to its own weight, and the shape of the entire substrate has a curved shape that protrudes downward, as shown in the front view inFIG. 12. In this case, the surface of the substrate S has different heights near the center and near the edge of the substrate S. Specifically, the surface near the center of the substrate S is lower than the surface near the edge of the substrate S. If the sponge is held at the same height when the cleaning head is located near the center and when the cleaning head is located near the edge, the sponge of the cleaning head is in contact with the surface of the substrate S with an appropriate contact pressure in the vicinity of the center of the substrate S, but the contact pressure becomes higher as the cleaning head becomes closer to the edge of the substrate S. Such unevenness in contact pressure is more conspicuous in a larger substrate.

FIGS. 13A through 13Care a cross-sectional view taken along the line A-A′ inFIG. 12, a cross-sectional view taken along the line B-B′ inFIG. 12, and a cross-sectional view taken along the line C-C′ inFIG. 12, respectively. InFIGS. 13A through 13C, the substrate S is moving to the left in each drawing. As shown inFIG. 12andFIGS. 13A through 13C, the sponge of the cleaning head is dragged by the substrate because of the frictional force between the substrate and the sponge, and is thus deformed. In a case where the cleaning head moves in a radial direction, if the rotating speed of the substrate is constant, the moving speed of the surface of the substrate S in contact with the cleaning head becomes higher relative to the cleaning head as the cleaning head moves outward in the radial direction of the substrate S. Therefore, as shown inFIGS. 13A and 13B, the cleaning head deformation due to the dragging by the substrate is greater when the cleaning head is located at an outer portion in the radial direction of the substrate. Such deformation is more conspicuous where the radius of the substrate is greater.

As the cleaning head is deformed, the cleaning head, which is originally designed to have a circular contact surface slidably in contact with the substrate surface, is pressed as shown in the plan view inFIG. 12, and the cleaning performance of the cleaning head deteriorates. Further, when the cleaning head rotates about an axis perpendicular to the substrate, the frictional force generated by the rotating substrate and the torque generated by the rotating cleaning head are applied to the sponge in a complicated manner, and great stress is locally applied to the sponge. As a result, the sponge can be detached from the holder.

The present technology has been made in view of the above problem, and an object thereof is to provide a novel substrate cleaning apparatus and a novel substrate cleaning method for cleaning the surface of substrate while moving a cleaning head in a radial direction of the substrate.

Solution to Problem

A substrate cleaning apparatus that cleans a substrate according to one embodiment includes: a substrate rotating supporter configured to support and rotate the substrate; a scrubbing member comprising a cleaning surface configured to clean a surface to be cleaned of the substrate being rotated by the substrate rotating supporter, the cleaning surface being brought into contact with the surface to be cleaned; a movement mechanism configured to move the scrubbing member in a radial direction of the substrate while maintaining the cleaning surface in contact with the surface to be cleaned; and a controller configured to control a contact pressure of the cleaning surface on the surface to be cleaned, wherein the controller sets the contact pressure of when the scrubbing member is located near an edge of the substrate to be smaller than the contact pressure of when the scrubbing member is located near a center of the substrate.

In this structure, the controller controls the contact pressure of the cleaning surface of the scrubbing member. Even in a case where the height of the surface near the edge is greater than the height of the surface near the center since the substrate is supported at the edge, the contact pressure can be prevented from becoming an unintended contact pressure due to the difference in height. Furthermore, the contact pressure near the edge at which the moving speed of the surface to be cleaned is high is reduced to a smaller value than the contact pressure near the center. Accordingly, it is possible to reduce the stress to be applied onto the scrubbing member when the cleaning surface of the scrubbing member in contact with the surface of the substrate to be cleaned is dragged by the surface to be cleaned that moves with the rotation of the substrate. Thus, the possibility of deformation or detachment of the scrubbing member can be lowered.

In the substrate cleaning apparatus, the controller may further control movement of the scrubbing member by the movement mechanism, and seta moving speed of the scrubbing member of when the scrubbing member is located near the edge of the substrate to be smaller than the moving speed of when the scrubbing member is located near the center of the substrate.

In this structure, in the vicinity of the edge where the moving speed of the surface to be cleaned of the substrate is high and the time of contact per unit area with the cleaning surface of the scrubbing member is short, the number of contact times can be increased by lowering the moving speed of the scrubbing member in a radial direction to a lower speed than in the vicinity of the center. Thus, the cleaning performance near the edge can be improved.

The substrate cleaning apparatus may further include a rotation mechanism configured to rotate the scrubbing member, wherein the controller further controls rotation of the scrubbing member by the rotation mechanism, and sets a rotating speed of the scrubbing member of when the scrubbing member is located near the edge of the substrate to be greater than the rotating speed of when the scrubbing member is located near the center of the substrate.

In this structure, it is possible to reduce degradation of the cleaning performance due to the decrease in the contact pressure between the surface to be cleaned of the substrate and the cleaning surface of the scrubbing member near the edge of the substrate. Furthermore, in a case where the moving speed of the scrubbing member is lowered near the edge of the substrate, an effect to improve the cleaning performance by virtue of the rotation of the scrubbing member is expected. Thus, the decrease in the moving speed of the scrubbing member can be reduced, and the decrease in productivity due to the decrease in the moving speed of the scrubbing member can be reduced accordingly.

In the substrate cleaning apparatus, the controller may control rotation of the substrate by the substrate rotating supporter, and set a rotating speed of the substrate of when the scrubbing member is located near the edge of the substrate to be greater than the rotating speed of when the scrubbing member is located near the center of the substrate.

In a case where the scrubbing member moves in a radial direction of the substrate at a constant speed, the number of times the scrubbing member is brought into contact with the substrate becomes smaller as the scrubbing member becomes closer to the edge of the substrate. However, such a decrease in the number of contact times can be reduced or avoided, if the rotating speed of the substrate at a time when the scrubbing member is located near the edge of the substrate is made higher than at a time when the scrubbing member is located near the center of the substrate as in the above described structure. Furthermore, to reduce such a decrease in the number of contact times, the moving speed of the scrubbing member at a time when the scrubbing member is located near the edge of the substrate may be made lower than at a time when the scrubbing member is located near the center of the substrate. In such a case, the decrease in the moving speed of the scrubbing member can be reduced, if the rotating speed of the substrate at a time when the scrubbing member is located near the edge of the substrate is made higher than at a time when the scrubbing member is located near the center of the substrate as in the above described structure. Thus, the decrease in productivity can be reduced.

In the substrate cleaning apparatus, the controller may vary the contact pressure while the cleaning surface is in contact with the center of the substrate.

In this structure, in the vicinity of the center of the substrate, it is also possible to control the contact pressure in accordance with the location of the scrubbing member in a radial direction of the substrate.

In the substrate cleaning apparatus, the movement mechanism may moves the scrubbing member on a predetermined movement locus comprising a location where the cleaning surface overlaps the edge of the substrate, and the controller may set the contact pressure of when the cleaning surface overlaps the edge of the substrate to be smaller than the contact pressure of when the cleaning surface does not overlap the edge of the substrate.

In this structure, a problem, such as deterioration of the scrubbing member due to a high contact pressure of the scrubbing member on the edge of the substrate, can be alleviated.

A substrate cleaning apparatus that cleans a substrate according to another embodiment includes: a substrate rotating supporter configured to support and rotate the substrate; a scrubbing member comprising a cleaning surface configured to clean a surface to be cleaned of the substrate being rotated by the substrate rotating supporter, the cleaning surface being brought into contact with the surface to be cleaned; a rotation mechanism configured to rotate the scrubbing member; a movement mechanism configured to move the scrubbing member in a radial direction of the substrate while maintaining the cleaning surface in contact with the surface to be cleaned; and a controller configured to control a contact pressure of the cleaning surface on the surface to be cleaned, wherein, the movement mechanism moves the scrubbing member on a predetermined movement locus comprising a location where the cleaning surface overlaps an edge of the substrate, and the controller sets the contact pressure of when the cleaning surface overlaps the edge of the substrate to be smaller than the contact pressure of when the cleaning surface does not overlap the edge of the substrate.

In this structure, a problem, such as deterioration of the scrubbing member due to a high contact pressure of the scrubbing member on the edge of the substrate, can be alleviated.

A substrate cleaning method of cleaning a substrate according to one embodiment, the method includes: supporting and rotating the substrate; and moving a scrubbing member in a radial direction of the substrate while maintaining a cleaning surface of the scrubbing member in contact with a surface to be cleaned of the substrate, wherein a contact pressure of the cleaning surface on the surface to be cleaned of when the scrubbing member is located near an edge of the substrate is set to be smaller than the contact pressure of when the scrubbing member is located near a center of the substrate.

In this structure, the contact pressure of the cleaning surface of the scrubbing member is controlled. Even in a case where the height of the surface near the edge is greater than the height of the surface near the center since the substrate is supported at the edge, the contact pressure can be prevented from becoming an unintended contact pressure due to the difference in height. Furthermore, the contact pressure near the edge at which the moving speed of the surface to be cleaned is high is reduced to a smaller value than the contact pressure near the center. Accordingly, it is possible to reduce the stress to be applied onto the scrubbing member when the cleaning surface of the scrubbing member in contact with the surface of the substrate to be cleaned is dragged by the surface to be cleaned that moves with the rotation of the substrate. Thus, the possibility of deformation or detachment of the scrubbing member can be lowered.

A substrate cleaning method of cleaning a substrate according to another embodiment includes: supporting and rotating the substrate; moving a scrubbing member in a radial direction of the substrate on a predetermined movement locus comprising a location where a cleaning surface of the scrubbing member overlaps an edge of the substrate while maintaining the cleaning surface of the scrubbing member in contact with a surface to be cleaned of the substrate; and rotating the scrubbing member, wherein a contact pressure of when the cleaning surface overlaps the edge of the substrate is set to be smaller than the contact pressure of when the cleaning surface does not overlap the edge of the substrate.

In this structure, a problem, such as deterioration of the scrubbing member due to a high contact pressure of the scrubbing member on the edge of the substrate, can also be alleviated.

A substrate cleaning apparatus that cleans a substrate according to another embodiment includes: a substrate rotating supporter configured to support and rotate the substrate; a two-fluid nozzle configured to jet a mixture of liquid and gas to a surface to be cleaned of the substrate being rotated by the substrate rotating supporter; a movement mechanism configured to move the two-fluid nozzle in a radial direction of the substrate; and a controller configured to control a flow amount of the liquid and/or the gas to be supplied to the two-fluid nozzle, wherein the controller sets the flow amount of the liquid and/or the gas of when the two-fluid nozzle is located near an edge of the substrate to be smaller than the flow amount of when the two-fluid nozzle is located near a center of the substrate.

In the vicinity of the edge of the substrate, the speed of the substrate relative to the two-fluid nozzle is high. Therefore, the substrate is damaged due to jetting from the two-fluid jet in some cases. In the above described structure, however, the flow amount of liquid and/or the flow amount of gas at a time when the two-fluid nozzle is located near the edge of the substrate are (is) made lower than at a time when the two-fluid nozzle is located near the center of the substrate. Accordingly, when the two-fluid nozzle is located near the edge of the substrate, the kinetic energy of the liquid to be jetted is smaller than that of when the two-fluid nozzle is located near the center of the substrate. Thus, the above mentioned damage can be reduced or avoided.

DESCRIPTION OF EMBODIMENTS

The following is a description of a substrate cleaning apparatus according to an embodiment of the present technology. It should be noted that the embodiment described below is an example case where the present technology is embodied, and does not limit the present technology to the specific structures described below. In embodying the present technology, any appropriate specific structure according to an embodiment may be employed. In the embodiment described below, a substrate cleaning apparatus to be used in a CMP system or the like that polishes semiconductor substrates is explained as an example.

FIG. 1is a plan view of the entire structure of a substrate processing apparatus that includes substrate cleaning apparatuses (cleaning units) according to an embodiment of the present technology. As shown inFIG. 1, the substrate processing apparatus includes a housing10of a substantially rectangular shape, and a load port12in which a substrate cassette that stores a large number of substrates such as semiconductor wafers is mounted. The load port12is disposed adjacent to the housing10. It is possible to mount an open cassette, a standard manufacturing interface (SMIF) pod, or a front opening unified pod (FOUP) in the load port12. A SMIF and a FOUP are an airtight container that can maintain an environment isolated from the external space by housing a substrate cassette therein and covering the substrate cassette with partitions.

The housing10houses four polishing units14athrough14d, cleaning units (a first cleaning unit16and a second cleaning unit18) that clean polished substrates, and a drying unit20that dries cleaned substrates. The cleaning units (the first cleaning unit16and the second cleaning unit18) may form a vertical two-tier structure in which the cleaning units are arranged in an upper tier and a lower tier. The polishing units14athrough14dare aligned in the longitudinal direction of the substrate processing apparatus, and the cleaning units16and18and the drying unit20are also aligned in the longitudinal direction of the substrate processing apparatus. Substrate cleaning apparatuses of the embodiment of the present technology can be used as the first cleaning unit16and the second cleaning unit18.

A first substrate conveying robot22is disposed in the region surrounded by the load port12, and the polishing unit14aand the drying unit20located on the side of the load port12, and a substrate conveying unit24is disposed parallel to the polishing units14athrough14d. The first substrate conveying robot22receives substrates yet to be polished from the load port12, and transfers the substrates to the substrate conveying unit24. The first substrate conveying robot22also receives dried substrates from the drying unit20, and transfers the dried substrates to the load port12. The substrate conveying unit24conveys substrates received from the first substrate conveying robot22, and transfers the substrates to the respective polishing units14athrough14d.

A second substrate conveying robot26that transfers substrates between the first cleaning unit16and the second cleaning unit18is disposed between the first cleaning unit16and the second cleaning unit18. A third substrate conveying robot28that transfers substrates between the second cleaning unit18and the drying unit20is disposed between the second cleaning unit18and the drying unit20. Further, a controller30that controls operations of the respective apparatuses in the substrate processing apparatus is disposed in the housing10.

FIG. 2is a perspective view of the structure of a substrate cleaning apparatus (cleaning unit) of this embodiment.FIG. 3is a side view of the structure of the substrate cleaning apparatus (cleaning unit).FIG. 4is a plan view of the structure of the substrate cleaning apparatus (cleaning unit). As shown inFIGS. 2 through 4, a substrate cleaning apparatus50includes four circumference supporting members51that support a substrate S at the circumference. The circumference supporting members51are formed with rotatable rollers that nip the edge of the substrate S in the vertical direction. In this embodiment, the four circumference supporting members51are located in the same horizontal plane, and the substrate S is horizontally supported by these four circumference supporting members51, with its front surface (the surface to be polished) facing upward. Some or all of the four circumference supporting members51are rotatively driven, and thus, the supported substrate S rotates. The circumference supporting member(s)51that is (are) not rotatively driven follow(s) the rotation of the substrate S, and thus rotate(s). The circumference supporting members51corresponds to the substrate rotating member.

The substrate cleaning apparatus50includes an arm support pillar52designed to vertically stand, an arm53elevatably and rotatably supported by the arm support pillar52, and a cleaning head54supported by the lower portion of the end of the arm53. Further, nozzles55that supply a cleaning solution (a cleaning liquid (chemical liquid), slurry, or pure water) to the surface (upper surface) of the substrate S stand by the substrate S supported by the circumference supporting members51. The structure formed with the arm support pillar52and the arm53is equivalent to the movement mechanism.

As shown inFIG. 4, the arm53rotates about a swing center OA. With this, the cleaning head54attached to the end of the arm53swings on the substrate S and moves along the surface of the substrate S as if drawing an arc. The arm53moves the cleaning head54on the substrate S in a radial direction of the substrate S so that the cleaning head54passes through the center of the substrate S. The arm53also moves the cleaning head54on the substrate S so that the cleaning head54reaches the edge of the substrate S. That is, the movement locus of the cleaning head54passes through the center of the substrate S, and even covers the edge of the substrate S.

As shown inFIG. 3, the cleaning head54includes a sponge541as a scrubbing member, a holder542that holds the sponge, and a driver543that lifts up and down and rotates the holder542. The driver543is provided inside the arm53. The holder542is supported in a position perpendicular to the substrate S by the driver543, and the driver543rotates the holder542about a rotation axis perpendicular to the substrate S. The driver543also lifts up or lowers the holder542in a direction perpendicular to the substrate S. The driver543is equivalent to the rotation mechanism.

The sponge541is secured to the lower end of the holder542, and rotates with the holder542. The sponge541has a circular cylindrical shape, and the circular bottom surface (polishing surface) thereof is brought into contact with the substrate S. The driver543brings the bottom surface of the sponge541into contact with the surface of the substrate S by lowering the holder542. Furthermore, with the sponge541being in contact with the substrate S, the driver543lifts up and down the holder542, to adjust the contact pressure of the sponge541on the surface of the substrate S. In this embodiment, the contact pressure of the sponge541on the surface of the substrate S is the pressing load per unit area of the sponge541on the surface of the substrate S.

FIG. 5is a block diagram showing the configuration of the control system of the substrate cleaning apparatus of this embodiment. The substrate cleaning apparatus50includes a controller60that controls cleaning operations thereof. This controller60may be the controller30of the substrate processing apparatus (seeFIG. 1), or may be provided separately from the controller30. The controller60is implemented by a computer executing a cleaning program of this embodiment, the computer including a memory and an arithmetic processing circuit. The substrate cleaning apparatus50includes a cleaning method storage61, an arm swinging driver62, a substrate rotating driver63, a head rotating driver64, and a head elevating driver65, as well as the controller60.

In the substrate cleaning apparatus50of the example shown inFIG. 5, the controller60controls the respective drivers32through35, according to a cleaning recipe (cleaning method) stored in the cleaning method storage61. However, the controller60may also perform a feedback control by a predetermined algorithm, in accordance with some sensing data obtained from the substrate cleaning apparatus50. The cleaning method storage61stores control values (the cleaning recipe) for the respective drivers32through35in accordance with the progress of (the elapsed time in) a cleaning process.

The arm swinging driver62drives the arm53to swing about the swing center OA, so that the cleaning head54moves on an arcuate trajectory parallel to the surface of the substrate S. The substrate rotating driver63drives the circumference supporting members51to rotate, so that the substrate S rotates about the central axis. The head rotating driver64drives the driver543to rotate, so that the holder542and the sponge541held by the holder542rotate about the central axis. The head elevating driver65drives the driver543to move up and down, so that the sponge541is brought into contact with the substrate S or the sponge541in contact with the substrate S is detached from the substrate S, and the contact pressure of the sponge541on the substrate S is adjusted.

In this embodiment, the arm53is also driven to move up and down relative to the arm support pillar52as described above. Therefore, the driver543of the cleaning head54may not have the function to lift up and down the holder542. In that case, the driver for lifting up and down the arm53relative to the arm support pillar52may be the head elevating driver65, instead of the driver543or in addition to the driver543. In this embodiment, the driver543brings the sponge541into contact with the substrate S or detaches the sponge541in contact with the substrate S from the substrate S, and adjusts the contact pressure of the sponge541on the substrate S. The driver for lifting up and down the arm53relative to the arm support pillar52is used in bringing the cleaning head54closer to the substrate S when the cleaning head54is at a distance from the substrate S, or in detaching the cleaning head54from the substrate S.

Next, a cleaning method to be implemented by the controller60in accordance with a cleaning recipe stored in the cleaning method storage61is described.FIG. 6is a diagram showing the movement locus of the sponge.FIG. 7is graphs showing the relationships among the location of the center of the sponge on the substrate, the rotating speed of the substrate, the moving speed of the arm, the contact pressure of the cleaning head on the substrate, and the rotating speed of the cleaning head.

The moving speed AS of the arm53varies with the location of the cleaning head54as shown inFIG. 7, as the controller60controls the arm swinging driver62in accordance with the cleaning recipe. The rotating speed SR of the substrate S varies with the location of the cleaning head54as shown inFIG. 7, as the controller60controls the substrate rotating driver63in accordance with the cleaning recipe. The rotating speed HR of the cleaning head54varies with the location of the cleaning head54as shown inFIG. 7, as the controller60controls the head rotating driver64in accordance with the cleaning recipe. The contact pressure HP of the cleaning head54on the substrate S varies with the location of the cleaning head54as shown inFIG. 7, as the controller60controls the head elevating driver55in accordance with the cleaning recipe. In the case described below, the cleaning head54moves from a point near the center of the substrate S toward the edge of the substrate S.

As shown inFIG. 6, the controller60controls the arm swinging driver62, to move the cleaning head54from the center of the substrate S toward the edge of the substrate S. Here, the radius of the sponge541is represented by Ra. Before the center of the sponge541reaches a location at a distance Rb (Rb≤Ra) from the center of the substrate S, the controller60controls the arm swinging driver62, the head elevating driver65, and the substrate rotating driver63, so that the moving speed AS of the arm53, the contact pressure HP of the cleaning head54on the substrate S, and the rotating speed SR of the substrate S become constant.

When the center of the sponge541reaches a location at the distance Rb from the center of the substrate S, that is, before the sponge541completely passes through the center of the substrate S, the controller60controls the arm swinging driver62and the head elevating driver65, so that the speed AS of the arm53and the contact pressure HP of the cleaning head54on the substrate S start decreasing.

After that, the controller60controls the arm swinging driver62and the head elevating driver65, so that the moving speed AS of the arm53and the contact pressure HP of the cleaning head54on the substrate S become lower as the center of the sponge541becomes closer to the edge of the substrate S (or moves toward the outer side). At this point, the rate of decrease in the moving speed AS of the arm53and the rate of decrease in the contact pressure HP of the cleaning head54on the substrate S become lower as the center location of the sponge541become closer to the edge of the substrate S (or moves toward the outer side). Accordingly, the graphs representing these rates are curves slightly protruding downward as shown inFIG. 7.

When the center location of the sponge541reaches a location at a distance Rc (Rc≥Ra) from the edge of the substrate S as the cleaning head54approaches the edge of the substrate S, that is, before the outer rim of the sponge541reaches the edge of the substrate S, the controller60controls the arm swinging driver62and the head elevating driver65, so that the moving speed AS of the arm53and the contact pressure HP of the cleaning head54on the substrate S start rapidly decreasing, and become zero at the time when the center of the sponge541reaches the edge of the substrate S, as shown inFIG. 7.

At a location where the distance between the outer rim of the sponge541and the edge of the substrate S is 0.5 mm to 1.0 mm before the outer rim of the sponge541reaches the edge of the substrate S, the moving speed AS of the arm53may be made 0, and thus, the arm53may be stopped. After the arm53is stopped, the arm53is again moved to such a location that the center of the sponge541reaches the edge of the substrate S.

When the center of the sponge541reaches a location at the distance Rb from the center of the substrate S, that is, before the sponge541completely passes through the center of the substrate S, the controller60controls the substrate rotating driver63, so that the rotating speed SR of the substrate S starts increasing. At this point, the controller60may increase the rotating speed at a constant increase rate, as indicated by a rotating speed SR1, or may increase the rotating speed in such a manner that the rotating speed becomes higher as the center of the sponge541becomes closer to the edge of the substrate S (or moves toward the outer side), as indicated by a rotating speed SR2. As shown inFIG. 7, the graph representing the rotating speed SR1is a straight line, and the graph representing the rotating speed SR2is a curve slightly protruding downward.

Until the center of the sponge541reaches a location at the distance Rb from the center of the substrate S, the controller60controls the head rotating driver64, so that the rotating speed HR of the cleaning head54becomes constant. When the center of the sponge541reaches a location at the distance Rb from the center of the substrate S, that is, before the sponge541completely passes through the center of the substrate S, the controller60controls the head rotating driver64, so that the rotating speed of the cleaning head54becomes higher as the center of the sponge541becomes closer to the edge of the substrate S (or moves toward the outer side).

The cleaning recipe in the substrate cleaning apparatus50has been described above, and the effects of this cleaning recipe are now described below. If the rotating speed of the substrate S is constant, the speed of the surface of the substrate S relative to the cleaning head54becomes higher as the cleaning head54becomes closer to the edge of the substrate S. Accordingly, the contact time in each contact action between the sponge541and the surface of the substrate S becomes shorter. In this embodiment described above, however, the controller60controls the arm swinging driver62so that the moving speed AS of the arm53, which is the moving speed of the cleaning head54in a radial direction of the substrate S, becomes lower as the cleaning head54becomes closer to the edge of the substrate S. In this manner, the number of times the sponge541comes into contact with the surface of the substrate S increases, and the total contact time can be made longer. As described above, the moving speed AS of the arm53is made lower as the cleaning head54becomes closer to the edge of the substrate S. Thus, it is possible to achieve higher cleaning performance than with a substrate cleaning apparatus in which the moving speed of the arm53is constant.

As described above, in this embodiment, the moving speed AS of the arm53is made lower as the cleaning head54becomes closer to the edge of the substrate S. To put this the other way around, the moving speed of the arm53is made higher as the cleaning head54becomes closer to the center of the substrate S. In the vicinity of the center of the substrate S, the circumferential moving speed of the surface of the substrate S relative to the cleaning head54is low, and therefore, the cleaning performance is poor. However, the deterioration of the cleaning performance is reduced, as the moving speed of the arm53, which is the moving speed in a radial direction of the cleaning head54, is made higher.

As described above, the moving speed AS of the arm53is made lower as the cleaning head54becomes closer to the edge of the substrate S. In this manner, the cleaning performance of the cleaning head54is improved. Meanwhile, the time required for the cleaning head54to reach the edge of the substrate S, which is the time required for cleaning a single substrate S, becomes longer, and the productivity becomes lower. In view of this, the controller60controls the head rotating driver64, so that the rotating speed HR of the cleaning head54becomes higher as the cleaning head54becomes closer to the edge of the substrate S in this embodiment, as shown inFIG. 7. In this manner, the cleaning performance per unit time is improved. Thus, the decrease in the moving speed AS of the arm53can be made smaller, and the decrease in the productivity can be reduced.

Furthermore, as described above, where the substrate S is supported at the edge, the substrate S has downward warpage due to its own weight. In a large-sized substrate like a 450-mm substrate, this warpage is more conspicuous. In the above described embodiment, however, the contact pressure of the sponge541on the surface of the substrate S is appropriately controlled. Thus, contact pressures are set at respective locations in accordance with changes in the in-plane height of the surface of the substrate S, and unintended increases and decreases in contact pressure due to warpage of the substrate S can be avoided.

Further, as shown inFIGS. 13A and 13B, the moving speed of the surface of the substrate S relative to the cleaning head54becomes higher as the cleaning head54becomes closer to the edge of the substrate S. Therefore, if the contact pressure of the sponge541on the surface of the substrate S is constant, the surface of the substrate S drags the bottom surface (cleaning surface) of the sponge541of the cleaning head54, and the sponge541is deformed. In this embodiment, on the other hand, the contact pressure of the sponge541on the surface of the substrate S is made lower as the cleaning head54becomes closer to the edge of the substrate S, as shown inFIG. 7. Thus, the deformation due to this dragging can be reduced. Although not shown inFIG. 7, when high cleaning performance is required at the outer circumference of the substrate S, control may be performed so that the contact pressure of the sponge541on the surface of the substrate S becomes higher as the cleaning head54becomes closer to the edge of the substrate S.

Furthermore, in a substrate cleaning apparatus in which a substrate S supported by the circumference supporting members51at the edge is rotated, the lower surface (cleaning surface) of the sponge541can move beyond the edge of the substrate S by virtue of swinging of the arm53. Thus, the edge of the substrate S can be cleaned as well. However, if the pressure of the sponge541on the surface of the substrate S is constant, the contact area between the sponge541and the substrate S becomes smaller when the sponge541reaches the edge of the substrate S, and local stress concentration occurs in the sponge541. In addition, the portion of the sponge541protruding from the edge of the substrate S is rubbed against the edge of the substrate S, and deteriorates. In this embodiment, on the other hand, the contact pressure of the sponge541on the surface of the substrate S is made lower immediately before the sponge541reaches the edge of the substrate S by virtue of swinging of the arm53. Because of this, the above described trouble that occurs when the cleaning head54reaches the edge of the substrate S can be avoided or reduced.

It should be noted that it is possible to perform only part of the above described control on the moving speed AS of the arm53, the rotating speed SR of the substrate S, the rotating speed HR of the cleaning head54, and the contact pressure HP of the cleaning head54on the substrate S, in accordance with the location of the cleaning head54in a radial direction of the substrate S. For example, the rotating speed HR of the cleaning head54may be constant, and the rotating speed SR of the substrate S may be constant.

In the above description, various control operations to be performed when the cleaning head54moves from the center of the substrate S to the edge of the substrate S have been described. However, the cleaning head54may move from the edge to the center. In that case, control can also be performed in the same manner as above. Specifically, as the cleaning head54becomes closer to the center of the substrate S, the moving speed AS of the arm53is increased, the contact pressure of the sponge541on the surface of the substrate S is increased, the rotating speed of the substrate S is lowered, and the rotating speed of the cleaning head54is lowered. Further, the arm53may be operated in such a manner that the cleaning head54moves from the edge on one side of the substrate S toward the center of the substrate S, and, after passing through the center of the substrate S, moves toward the edge on the opposite side.

The following is a description of other example structures of substrate cleaning apparatuses. In the above described embodiment, one end of the arm53holds the cleaning head54, and the arm53is rotated about the other end thereof so as to swing the cleaning head54and move the cleaning head54from the center of a substrate S to the edge of the substrate S. However, the other structures described below may also be employed to move the cleaning head54from the center of a substrate S to the edge of the substrate S.

FIG. 8is a plan view of the structure of a substrate cleaning apparatus according to a modification. As shown inFIG. 8, a substrate cleaning apparatus501horizontally holds a substrate S with four circumference instruction members51. A cleaning head54is attached to the lower surface of one end of an arm53, and the other end of the arm53is held by a rail521extending in a vertical direction on a side of the substrate S so that the other end of the arm53can move in the longitudinal direction of the rail521. As the other end of the arm53moves along the rail521, the arm53moves parallel to the rail521. Accordingly, the cleaning head54attached to one end of the arm53moves parallel to the rail521and along the surface of the substrate S.

FIGS. 9A and 9Bare a plan view and a side view of the structure of a substrate cleaning apparatus according to another modification. In a substrate cleaning apparatus502of this modification, a substrate S is vertically held by three circumference supporting members51. The two circumference supporting members51on the lower side are rotatively driven, and the one circumference supporting member51on the upper side follows rotation of the substrate S and thus rotates. A cleaning head54is attached to one end of an arm53. The other end of the arm53is rotatably supported. In the substrate cleaning apparatus502of this modification, a nozzle55supplies a solution such as a chemical liquid from obliquely above to the surface (the surface to be polished) of the substrate S.

FIGS. 10A and 10Bare a plan view and a side view of the structure of a substrate cleaning apparatus according to another modification. In a substrate cleaning apparatus503of this modification, a substrate S is also vertically held by circumference supporting members51. The two circumference supporting members51on the lower side are rotatively driven, and the two circumference supporting members51on the upper side follow rotation of the substrate S and thus rotate. A cleaning head54is attached to one end of an arm53. The other end of the arm53is supported by a rail522extending in a horizontal direction below the substrate S so that the other end of the arm53can move in the longitudinal direction of the rail522. As the other end of the arm53moves along the rail522, the arm53moves parallel to the horizontal direction. Accordingly, the cleaning head54moves in a horizontal direction along the surface of the substrate S.

FIGS. 11A and 11Bare a plan view and a side view of the structure of a substrate cleaning apparatus according to another modification. In a substrate cleaning apparatus504of this modification, a substrate S is obliquely held. Circumference supporting members51, an arm53, a cleaning head54, and a nozzles55have the same structures as those in the substrate cleaning apparatus502shown inFIGS. 9A and 9B, but are designed to obliquely hold and clean the substrate S.

In the embodiment and the modifications described above, the cleaning head54has the sponge541, and the sponge541is brought into contact with the surface of the surface (the surface to be polished) of a substrate S, to scrub the surface of the substrate S. However, the cleaning head54may be designed to clean the surface of the substrate S in a non-contact manner with a two-fluid jet. The two-fluid jet cleaning head54mixes a liquid such as a chemical liquid with a gas, and jets the mixture onto the surface of a substrate S, to clean the surface of the substrate S.

In this case, it is possible to control the amount of fluid and the jet pressure, instead of controlling the rotating speed of the cleaning head54and the contact pressure of the sponge541on the surface of the substrate S as described above. Specifically, the amount of fluid may be increased as the cleaning head54becomes closer to the edge of the substrate S. In this manner, the amounts of liquid and gas to be jetted per unit area of the substrate S can be made constant.

Meanwhile, in the vicinities of the edge of the substrate S, the speed of the substrate relative to the cleaning head54is higher, and the substrate (particularly, a low-K material or the like) is damaged by jetting from a two-fluid jet in some cases. In such a case, the flow amount of the liquid may be lowered (M is lowered), the flow amount of the gas may be lowered (V is lowered), or both of the rates may be lowered, so that the kinetic energy ½MV2(M being the mass of jetting, V being the velocity of jetting) becomes smaller at the circumference than at the center. As for the control on the rotating speed of the substrate, the moving speed of the arm, and the like, the same control as that of the above described embodiment can be performed to achieve the same effects as those described above.

In the embodiment and the modifications described above, the sponge541is moved up and down relative to the substrate S so as to vary the contact pressure between the cleaning surface of the sponge541and the surface of the substrate S to be cleaned. However, the substrate S may be lifted up and down so as to vary the contact pressure.

In the above described embodiment, the rotating speed SR of the substrate, the moving speed AS of the arm, the contact pressure HP of the cleaning head on the substrate, and the rotating speed HR of the cleaning head vary continuously from the center of the substrate S to the edge of the substrate S. However, those values may vary in a stepwise manner.

A preferred embodiment that is conceivable at present has been described so far. However, various modifications may be made to the embodiment of the present technology, and the claims should be construed as including all such modifications within the true spirit and scope of the present technology.

INDUSTRIAL APPLICABILITY

The present technology is useful as a substrate cleaning apparatus and a substrate cleaning method for cleaning the surface of a substrate while moving a cleaning head in a radial direction of the substrate.

REFERENCE SIGNS LIST