JP2007136637A - Magnetic field assisted micropolishing device and magnetic field assisted micropolishing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic field assisted micropolishing device enabling micropolishing of the surface to be polished and a magnetic field assisted micropolishing method, capable of eliminating as much as practicable bias workmanship of polishing, even when the surface includes a plurality of regions in mixture having different characteristics to accept polishing. <P>SOLUTION: The magnetic field assisted micropolishing device 10 is equipped at least with a holding member 12 to hold a work 1 to be polished, a first magnet 14 positioned facing the surface to be polished 2 of the work 1 held by the holding member 12, in an arrangement such that a prescribed gap S is reserved in the area facing the surface 2, and a first driving means to put the holding member 12 and the first magnet 14 in rotation and/or horizontal vibration relatively within a virtual plane approximately parallel with the surface 2, and a polish supply means for supplying the gap S between the surface 2 and the first magnet 14 with a polish, consisting of magnetic abrasive grains, polish grains containing magnetic particles, and/or a polishing slurry containing the magnetic abrasive grains or the polish grains. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a magnetically assisted fine polishing apparatus and method that enables fine polishing of a surface to be polished of an object to be polished, and more specifically, even a surface to be polished in which regions having different characteristics to be polished are mixed. The present invention relates to a magnetically assisted fine polishing apparatus and method that can eliminate bias as much as possible.

  Copper wiring may be applied as wiring of an integrated circuit (IC). This copper wiring is usually formed by a method called a damascene method. In the damascene method, first, a wiring groove (also referred to as a trench) is formed in a portion of each IC where copper wiring is applied, and a copper layer having a thickness that is sufficient to fill the depth of the trench is plated on the entire surface of the silicon wafer. After that, the copper layer formed on the entire surface of the silicon wafer is polished by a combination of chemical dissolution and mechanical polishing called chemical mechanical planarization (CMP). In this method, an excess portion is removed and only the copper buried in the trench is left to form a copper wiring.

  The chemical mechanical planarization polishing method (CMP method) is performed by, for example, supplying a polishing liquid (slurry) containing silica particles to the wafer surface while polishing or polishing the surface of the wafer attached or chucked to the spindle. In this method, the surface to be polished is brought into contact with the polishing pad on the surface, and the surface to be polished of the wafer and the surface of the polishing plate are directly brought into pressure contact and rubbed to collectively polish the surface to be polished of the wafer.

  However, since the CMP method is a polishing method in which rigid bodies are directly brought into pressure contact with each other, distortion of the wafer, uneven thickness of the wafer, variation in inclination when the wafer is fixed to the wafer holder, flat surface of the polishing plate surface. There is a problem that various non-uniform factors such as insufficient degree tend to affect uniform polishing of the wafer surface. For such a problem, for example, the pressure applied to the surface to be polished is made uniform using a buff, or the polishing slurry is uniformly supplied to the surface to be polished of the wafer. In any case, it has been difficult to uniformly polish the surface to be polished by applying an equal pressure to the surface to be polished.

  In addition, if pressure non-uniformity exists in the surface to be polished, partial rolling may occur on the surface on which a soft and malleable metal such as copper is formed.

  Therefore, in the conventional CMP method as described above, there are still many problems to perform uniform polishing on the surface to be polished of the wafer, and the slowest polishing portion in the surface to be polished is the processing end point (for example, unnecessary). If polishing is performed until reaching the point of time when copper is completely removed, there is a problem that a portion where excessive polishing is performed is generated in the surface to be polished. In the portion where overpolishing has been performed, for example, the wiring trench portion where copper is exposed on the surface and the portion where the insulating oxide or barrier metal other than copper is exposed on the surface have different polishing characteristics. There is a problem that the copper in the trench for use is polished to thin the copper wiring and the flatness characteristic of the CMP method is impaired.

  Furthermore, in the conventional CMP method, a strong frictional pressure is applied to the surface to be polished, so that there is a risk of damage such as cracks in the insulating layer used for wiring formation. There is also a problem that a promising insulating layer material having a resistance cannot be adopted due to brittleness.

  The present invention has been made in order to solve the above-described problems, and the object of the present invention is to eliminate unevenness of polishing as much as possible even on a surface to be polished in which regions having different characteristics to be polished exist. An object of the present invention is to provide a magnetic-assisted fine polishing apparatus and a magnetic-assisted fine polishing method that enable fine polishing of a polished surface.

  In order to solve the above problems, a magnetically assisted fine polishing apparatus of the present invention includes a holding member for holding an object to be polished, a surface to be polished of the object to be polished held by the holding member, and the surface to be polished. And / or relatively rotating and / or rotating the first magnet disposed with a predetermined gap between the first holding magnet and the first magnet in a virtual plane substantially parallel to the surface to be polished. Magnetic abrasive grains, abrasive grains containing magnetic grains, and magnetic abrasive grains or the abrasive grains are contained in a gap between the first drive means for horizontal vibration and the surface to be polished and the first magnet. And an abrasive supply means for supplying an abrasive selected from the polishing slurry.

  According to the present invention, since the surface to be polished and the first magnet are arranged with a predetermined gap and the abrasive is supplied to the gap, the abrasive supplied to the gap is provided. However, the surface to be polished is polished by the relative movement of the holding member and the first magnet. As a result, the surface to be polished can be polished without direct pressure contact as in the conventional CMP method. Such a magnetically assisted fine polishing apparatus of the present invention is a wafer-like polishing having various non-uniform factors such as wafer distortion, wafer thickness non-uniformity, and variation in inclination when the wafer is fixed to a holding member. Even an object can achieve uniform polishing of the surface to be polished, and can be applied, for example, to a copper damascene wiring formation process without causing alteration such as partial rolling. Similar effects can be preferably applied to a solder paste printing mask for producing a printed wiring board.

  The magnetic-assisted fine polishing apparatus of the present invention can be configured to include a second magnet on the opposite side of the first magnet across the holding member.

  According to the present invention, since the second magnet is disposed on the opposite side of the first magnet with the holding member interposed therebetween, the two magnets (the first magnet and the second magnet) disposed with the holding member interposed therebetween. By moving the magnet) relative to the holding member, it is possible to enhance the uniform polishing effect by the abrasive supplied to the gap between the holding member and the first magnet. The magnetism of the second magnet and the magnetism of the first magnet preferably constitute opposite magnetism, and as a result, the magnetism in the NS field composed of the first magnet and the second magnet. The uniform polishing effect by the abrasive grains can be enhanced. Further, by using an electromagnet capable of changing the magnetic field of the second magnet, the friction between the magnetic abrasive grains and the surface to be polished can be controlled, and uniform fine polishing can be realized.

  In the magnetic-assisted fine polishing apparatus of the present invention, when the second magnet is disposed, the holding member and the second magnet are relatively rotated and rotated in a virtual plane substantially parallel to the surface to be polished. It can comprise so that it may have the 2nd drive means to carry out horizontal vibration. According to the present invention, the second magnet may be moved so as to be synchronized with the first magnet, or may be moved independently of the first magnet.

  In the magnetic-assisted fine polishing apparatus of the present invention, the first magnet has a buff attached with an adhesive or a buff held by the magnetic force of the magnet at the tip of the first magnet facing the surface to be polished. Can be configured. The buff is preferably coated with an electroless plating film containing dispersed magnetic abrasive grains.

  In the magnetic-assisted fine polishing apparatus of the present invention, the magnetic abrasive grains are preferably formed by forming a magnetic plating film containing abrasive particles dispersed on the particle surface.

  In the magnetic-assisted fine polishing apparatus of the present invention, the polishing object is preferably applied to a case where regions to be polished are mixed on the surface to be polished. For example, the object to be polished is preferably a wafer or damascene solder mask printing mask for producing a printed wiring board.

  The magnetic-assisted fine polishing method of the present invention for solving the above problems is performed using the magnetic-assisted fine polishing apparatus of the present invention.

  According to the magnetic-assisted fine polishing apparatus or method of the present invention, the surface to be polished and the first magnet are arranged at a predetermined interval, and the abrasive is supplied to the gap. The polishing material supplied to the gap polishes the surface to be polished by the relative movement of the holding member and the first magnet. As a result, the surface to be polished can be polished without direct pressure contact as in the conventional CMP method. Such a magnetic-assisted fine polishing apparatus or method of the present invention has a hardness such as a wafer having various non-uniform factors such as wafer distortion, wafer thickness non-uniformity, and variation in inclination when the wafer is fixed to the holding member. A surface to be polished in which fine regions having different polishing characteristics represented by malleability, brittleness, chemical properties, and the like are mixed can be polished to a uniform and excellent surface.

  When the magnetically assisted fine polishing apparatus or method of the present invention is applied to a copper damascene wiring formation process, alteration such as partial rolling can be prevented, and the copper wiring in the wiring trench is polished. It is possible to prevent the flatness from being lost. In addition, since strong frictional pressure is not applied to the surface to be polished, there is no risk of damage such as cracks in the insulating layer used for wiring formation, etc. Promising insulating layer material with desired characteristics related to dielectric constant, for example, is adopted It is also possible to do.

  In addition, if the magnetic-assisted fine polishing apparatus and method of the present invention are applied to a method for forming a copper damascene wiring, copper polishing can be performed without excess or deficiency without applying strong pressure over the entire wafer surface in the copper polishing step. The thinning of the copper wiring can be reduced. As a result, it is possible to improve the yield of IC products, improve the reliability, reduce costs associated therewith, and realize an environmentally friendly process by not using chemical solutions.

  Further, in the conventional polishing method, the entire surface to be polished could only be polished at once, but according to the magnetic-assisted fine polishing apparatus and method of the present invention, the shape of the first magnet and the first magnet or holding By combining the movement of the member, a part of the surface to be polished can be selectively polished, or the surface to be polished can be subjected to sweep polishing or batch polishing.

  In addition, the polishing apparatus or method without large pressure, which is a feature of the magnetic-assisted fine polishing apparatus or method of the present invention, can perform polishing of a very thin layer with good control, and a polishing method using a strong pressure is applied. In addition to making it possible to polish materials that could not be made, it is also possible to apply to a wide range of nano-level polishing.

  Hereinafter, although the magnetic assistance fine polishing apparatus and method of the present invention will be described, the present invention is not limited to the following embodiments as long as it has the technical idea.

  FIG. 1 is a schematic configuration diagram showing an example of a magnetic-assisted fine polishing apparatus of the present invention. FIG. 2 is a schematic partial configuration diagram showing another example of the magnetic-assisted fine polishing apparatus of the present invention. As shown in FIG. 1, the magnetic-assisted fine polishing apparatus 10 of the present invention faces a holding member 12 that holds an object 1 to be polished and a surface 2 to be polished of the object 1 that is held by the holding member 12. In addition, the first magnet 14, the holding member 12, and the first magnet 14 that are disposed with a predetermined gap S between the surface 2 and the polished surface 2 are virtually parallel to the surface 2 to be polished. In the gap S between the surface to be polished 2 and the first magnet 14, the magnetic abrasive grains, the abrasive grains containing magnetic particles, And at least abrasive supply means 18 for supplying an abrasive 5 selected from magnetic abrasive grains or a polishing slurry containing the abrasive grains. Hereinafter, each configuration will be described in detail.

(Polishing object)
Examples of the polishing object 1 that is preferably applied to the present invention include various objects that require fine polishing, and it is preferable that the surface 2 to be polished has a mixture of regions having different characteristics to be polished. For example, a wafer including a damascene structure of a metal wire layer, a solder paste printing mask for producing a printed wiring board, and the like can be given. Further, the present invention can be preferably applied to a polishing object 1 that needs to be polished by a certain thickness without processing the entire surface 2 to be polished into a flat surface. Such polishing of the polishing object 1 was impossible with the conventional CMP method, but is possible with the magnetic-assisted fine polishing apparatus of the present invention. When the polishing object 1 as described above is polished by the magnetic-assisted fine polishing apparatus 10 of the present invention, the entire surface 2 to be polished can be polished finely and flatly without excess or deficiency. In particular, the present invention can be preferably applied to a copper polishing process for forming a copper damascene wiring on a silicon wafer and a manufacturing process of a solder paste printing mask for producing a printed wiring board.

(Holding member)
The holding member 12 is a member that holds the object 1 to be polished, and is opposed to the first magnet 14 with a predetermined gap S therebetween. The gap S can be arbitrarily changed depending on the type of polishing object 1, the polishing form, the type of abrasive 5, and the like, but is usually adjusted to a range of 0.05 mm to 5 mm. The holding member 12 holds the surface to be polished 2 of the object to be polished 1 on the first magnet 12 side.

  When holding the polishing object 1 whose back surface is flat, such as a silicon wafer, the holding member 12 is a surface on the side in contact with the polishing object 1 (hereinafter, holding surface 3). The holding surface 3 may have a partial recess such as a vacuum hole for suction or a vacuum groove. However, in the case where a partial recess is provided in the holding surface 3, it is assumed that the holding surface 3 can hold the polishing object 1 flat.

  As a holding method of the polishing object 1 to the holding member 12, a method of attaching the polishing object 1 to the holding member 12 with an adhesive or the like, or a polishing object 1 using a vacuum hole or a vacuum groove formed in the holding member 12. And the like. In addition, when the object to be polished 1 is a columnar or cylindrical object and the surface 2 to be polished is the end surface thereof, or when it is the end surface of another irregularly shaped object, the holding member 12 Any part other than the surface to be polished may be held by a vise or a gripping means such as a fastener.

  The width of the holding surface 3 is desirably greater than or equal to the maximum dimension of the polishing object 1, but may be less than the maximum dimension of the polishing object 1 as long as the polishing object 1 can be held without distortion or deformation. I do not care. Further, an inclination adjusting mechanism 26 such as a height adjusting screw may be provided on the four sides of the holding member 12, and the surface inclination of the holding member 12 can be adjusted by the inclination adjusting mechanism 26.

  The holding member 12 is opposed to the first magnet 14 by a moving means (not shown in FIG. 1) such as a moving screw or a sliding mechanism driven manually or by a motor (Z direction: vertical direction in FIG. 1). Z). The movement is controlled manually or automatically by a movement distance adjusting mechanism (not shown in FIG. 1), and between the surface to be polished 2 of the polishing object 1 held by the holding member 12 and the first magnet 14. The interval S can be adjusted arbitrarily. Further, the moving distance adjusting mechanism may have a detection mechanism (not shown in FIG. 1) that detects the interval S between the surface to be polished 2 and the first magnet 14. The moving means may be omitted when the first magnet 14 described later is provided, or both the holding member 12 and the first magnet 14 may be provided.

(First magnet)
The first magnet 14 opposes the surface 2 to be polished of the object 1 to be polished held by the holding member 12 and is disposed with a predetermined gap S between the first magnet 14 and the surface 2 to be polished. In the first magnet 14 thus arranged, the polarity on the side facing the polishing object 1 may be an N pole or an S pole.

  As a kind of the first magnet 14, a permanent magnet such as an NdFeB magnet can be preferably used, but an electromagnet may be used.

  The first magnet 14 may be composed of a single magnet bar as shown in FIG. 1, or may be composed of a plurality of magnet bars as shown in FIG. When the first magnet 14 is constituted by a plurality of magnet rods, the magnetic poles on the polished surface 2 side may be the same or different.

  When a plurality of magnet rods are used and the magnetic poles on the polished surface 2 side are the same, as shown in FIG. 2, the individual magnet rods are arranged apart from each other and are bundled by a fixture 28. It is preferable that Since the first magnet 14 having such a structure can substantially increase the length of the corner portion on the surface to be polished 2 side, the abrasive 5 such as magnetic abrasive grains can be turned to the corners of the end surfaces of the individual magnet bars. There is an advantage that the portion (that is, the circumferential length portion of the end face of the magnet bar) can be magnetized more. Further, a plurality of magnet rods may be used and the magnetic poles on the polished surface 2 side may be bundled alternately. In this case, although not shown, among the other ends of the individual magnet rods (the end portions that are not on the polishing object 1 side), magnetic poles having different polarities are connected to each other in pairs or collectively with a yoke. Is preferable, and as a result, the magnetic abrasive grain attractive force on the polishing object 1 side can be increased.

  When an electromagnet is used as the first magnet 14, a DC power supply is preferably used as a power supply (not shown in FIG. 1). The direct current power source can fix the polarity of each magnetic pole, and can increase the attractive force of the magnetic abrasive grains. On the other hand, the AC power supply is disadvantageous in terms of the attractive force of the magnetic abrasive grains because the polarity of the magnetic poles alternately changes, and the polishing efficiency is reduced, but it is advantageous from the viewpoint of the apparatus cost and operation cost.

  In addition, as illustrated in FIG. 2, a plurality of first magnets 14 can be attached to a fixture 28 that is parallel to the surface 2 to be polished. The fixture 28 is a rod-like or cylindrical nonmagnetic material. Or it can be comprised with a magnetic body. As described above, when the yoke is joined to the plurality of first magnets 14 having the same polarity, the yoke can be used as the fixture 28.

  The first magnet 14 can be moved in the direction facing the holding member 12 (Z direction) by moving means (not shown in FIG. 1) such as a moving screw or a sliding mechanism driven manually or by a motor. it can. The movement is controlled manually or automatically by a movement distance adjusting mechanism (not shown in FIG. 1), and between the first magnet 14 and the surface 2 to be polished of the object 1 held by the holding member 12. The interval S can be adjusted arbitrarily. Further, the moving distance adjustment mechanism may have a detection mechanism (not shown in FIG. 1) that detects the distance S between the first magnet 14 and the surface 2 to be polished. This moving means may be omitted when the holding member 12 is provided, or both the holding member 12 and the first magnet 14 may be provided.

(First driving means)
As shown in FIG. 1, the first driving means 16 relatively rotates and / or horizontally vibrates the holding member 12 and the first magnet 14 within a virtual plane 2a substantially parallel to the surface 2 to be polished. It is. In FIG. 1, the first driving means 16 is provided with the first magnet 14, but the holding member 12 may be provided, or both may be provided.

  First, the case where the holding member 12 includes the first driving means will be described. The holding member 12 is moved in a direction orthogonal to the facing direction of the first magnet 14 by a moving means such as a moving screw or a sliding mechanism driven manually or by a motor, that is, a direction parallel to the holding surface 3 of the holding member 12. It can be moved in (X direction and Y direction). Such movement can be performed by an XY movement mechanism, and the surface 2 to be polished of the object 1 can be moved to a position facing the first magnet 14.

  By the movement of the holding member 12, the polished surface 2 of the polishing object 1 is adjusted to a predetermined position. Thereafter, the first driving means rotates or horizontally vibrates the holding member 12, whereby the polished surface 2 and the first magnet 14 rotate relatively in a virtual plane 2 a substantially parallel to the polished surface 2. Or it vibrates horizontally.

  Although not shown in FIG. 1, the rotation of the holding member 12 is a rotation mechanism that drives a gear directly attached to the holding member 12 with a motor, or a rotation mechanism that drives a spindle connected to the holding member 12 with a motor via a gear mechanism. The surface 2 to be polished and the first magnet 14 can be relatively rotated in a virtual plane 2a substantially parallel to the surface 2 to be polished. On the other hand, with respect to the horizontal vibration of the holding member 12, an imaginary plane 2 a that is substantially parallel to the surface to be polished 2 is made to move the surface to be polished 2 and the first magnet 14 by vibration means that converts rotation by the motor into linear vibration by a cam. The linear vibration can be performed with a predetermined amplitude in either the X direction or the Y direction. It is also possible to vibrate elliptically by vibrating simultaneously in both the X and Y directions.

  Next, as shown in FIG. 1, the case where the first magnet 14 includes the first driving means 16 will be described. The first magnet 14 is moved in a direction perpendicular to the direction facing the holding member 12, that is, a direction parallel to the holding surface 3 of the holding member 12 by moving means such as a moving screw or a sliding mechanism driven manually or by a motor. It can be moved in (X direction and Y direction). Such movement can be performed by an XY movement mechanism, and the first magnet 14 can be moved to a position facing the surface to be polished 2 of the object 1 to be polished.

  By the movement of the first magnet 14, the first magnet 14 is adjusted to a predetermined position facing the polished surface 2. Thereafter, as shown in FIG. 1, the first driving means 16 rotates or horizontally vibrates the first magnet 14 so that the first magnet 14 and the surface 2 to be polished are substantially parallel to the surface 2 to be polished. Relatively rotate or horizontally oscillate in the virtual plane 2a.

  The rotation of the first magnet 14 is a rotation mechanism that drives a gear directly attached to the first magnet 14 with a motor, a rotation mechanism that drives a spindle connected to the first magnet 14 with a motor via a gear mechanism, or the like. The first driving means 16 can rotate the first magnet 14 and the surface 2 to be polished relative to each other within a virtual plane 2a substantially parallel to the surface 2 to be polished. On the other hand, for the horizontal vibration of the first magnet 14, the first magnet 14 and the surface 2 to be polished are virtually parallel to the surface 2 to be polished by vibration means that converts rotation by the motor into linear vibration by a cam. It is possible to vibrate linearly with a predetermined amplitude in either the X direction or the Y direction within the plane. It is also possible to cause elliptical vibration by simultaneously vibrating in both the X and Y directions.

(Abrasive supply means)
As shown in FIG. 1, the abrasive material supply means 18 includes magnetic abrasive grains, abrasive grains containing magnetic particles, and magnetic abrasive grains or abrasive grains in the gap S between the surface to be polished 2 and the first magnet 14. A polishing material 5 selected from a polishing slurry containing s. The supply of the abrasive 5 by the abrasive supply means 18 may be directly supplied to the gap S between the polished surface 2 and the first magnet 14 or may be supplied in the vicinity of the gap S.

  Examples of the abrasive material supply means 18 include supply means capable of spraying or dropping an appropriate amount of the abrasive material 5. Specific examples include those having a nozzle made of a non-magnetic material or impermeable magnet. The injection amount and dripping amount of the abrasive 5 and the injection time and dripping time thereof can be controlled by adjusting the opening and closing of a solenoid valve provided in the middle of the conduit connected to the nozzle. Such abrasive supply means 18 may be provided along the side surface of the first magnet 14, or may be formed integrally with the first magnet 14 by providing a guide hole in the first magnet 14 itself. However, it may be arranged at a position where the influence of the magnetic force of the first magnet 14 is relatively small.

A storage tank for storing the abrasive 5 is continuously provided in the abrasive supply means 18. The storage tank is preferably provided with an adjustment replenishment system that detects the internal volume and composition concentration and keeps the internal volume and composition concentration constant. The detection of the internal volume and the composition concentration may be an electrical detection device or an optical detection device. The injection amount and dripping amount of the abrasive 5, and the injection time and dripping time thereof are adjusted by opening and closing the solenoid valve provided in the middle of the conduit, as well as opening and closing adjustment of the delivery pressure valve provided in the conduit fed from the storage tank to the nozzle. Can also be controlled.
(Abrasive)
Examples of the abrasive 5 include magnetic abrasive grains, abrasive grains containing magnetic particles, or polishing slurries containing magnetic abrasive grains or abrasive grains.

  Examples of the magnetic abrasive grains include a magnetic powder having a hardness higher than that of the object 1 to be polished, a composite powder in which a nonmagnetic powder having a hardness higher than that of the object 1 to be polished and a magnetic material are integrated. . Examples of the latter composite powder include those obtained by forming a magnetic plating film containing abrasive particles dispersed on the particle surface. As an example, as shown in FIG. 3, for example, magnetic abrasive grains 32 each having a nickel / cobalt plating film 38 containing diamond fine particles 36 dispersed on the surface of a small plastic ball 34 having a diameter of about 10 μm are provided. Needless to say, the present invention is not limited to this form. The material, size, shape, etc. of the magnetic abrasive grains are appropriately selected according to the desired polishing rate, the nature of the solvent liquid when making the slurry, the size shape of the microstructure on the surface 2 to be polished 1, etc. Can be determined.

  The abrasive 5 does not prevent the chemical chemical solution from being used together with the conventional CMP method, but does not necessarily require the chemical solution.

(Buff)
You may comprise so that it may have the buff 24 in the front-end | tip of the side which opposes the to-be-polished surface 2 of the 1st magnet 14. FIG. The buff 24 may be provided by being attached to the tip of the first magnet 14 with an adhesive, or may be provided by being magnetized at the tip of the first magnet 14 by the magnetic attractive force of the magnet. FIG. 4 is a schematic cross-sectional view showing an example of the first magnet 14 provided with the buff 24.

  Preferred examples of the buff 24 include those made of fibers and coated with an electroless plating film containing magnetic abrasive grains in a dispersed manner. The buff 24 thus provided can improve the retention of magnetic abrasive grains that are magnetized by the magnetic attractive force of the first magnet 14, and as a result, between the surface to be polished 2 and the first magnet 14. It is possible to evenly perform the polishing action that works on. Further, since the material of the buff 24 is composed of fibers, it can also have a buffering action, and the polishing action can be performed more evenly.

  The effect of improving the retention of magnetic abrasive grains associated with the use of the buff 24 can contribute to a reduction in the consumption of magnetic abrasive grains. Further, the formation of giant particles due to the aggregation of the magnetic abrasive grains can be prevented to prevent excessive supply of the magnetic abrasive grains, and as a result, the surface 2 to be polished can be effectively prevented from being rough.

  The equal effect of the polishing action acting between the surface to be polished 2 and the first magnet 14 is due to the fact that the polishing pressure is dispersed and equalized due to the presence of the buff 24. Further, the buffering effect of the polishing action that acts between the surface to be polished 2 and the first magnet 14 is effective even when the magnetic abrasive grains are slightly agglomerated to form giant particles. This is derived from the fiber material constituting the buff 24.

  The magnetic abrasive grains in the dispersion plating film formed on the buff 24 are mainly subjected to lateral force during polishing. Therefore, in combination with the cushioning property of the buff 24, the surface to be polished 2 is softer than the floating abrasive grains, and precision finish polishing with a good surface condition is possible. Note that the distance S ′ between the buff 24 and the surface 2 to be polished is preferably determined in consideration of the fragility of the surface 2 to be polished, and may be, for example, a slight distance S ′ or in a substantially contacted state. Alternatively, it may be lightly pressed against the surface 2 to be polished as long as the cushioning property of the buff 24 is not lost.

(Second magnet)
If necessary, the second magnet 22 can be provided on the opposite side of the holding member 12 as viewed from the first magnet 14 side. When the second magnet 22 is provided, it is desirable that the second magnet 22 is disposed at a position substantially opposite to the first magnet 14 with the holding member 12 interposed therebetween. The second magnet 22 may be provided in close contact with the holding member 12 or may be provided away from the holding member 12.

  Similar to the first magnet 14, the second magnet 22 may be composed of a single magnet rod or may be composed of a plurality of magnet rods. Further, as the type of the second magnet 22, a permanent magnet such as an NdFeB magnet can be preferably used as in the case of the first magnet 14, but an electromagnet may be used. The polarity of the second magnet 22 is preferably opposite to the polarity of the first magnet 14. However, when an electromagnet is used for the second magnet 22 and / or the first magnet 14, the second magnet 22 has a second polarity. The polarity of the magnet 22 may be the same as or opposite to the polarity of the first magnet 14.

  When the first magnet 14 has a configuration in which magnet rods having different polarities are bundled, the polarity of the second magnet 22 may be any polarity, and the second magnet 22 is bundled with magnet rods having different polarities. It is good also as a structure. Further, the holding member 12 itself may be the second magnet 22, or the second magnet 22 may be magnetized and arranged on the holding member 12 formed of a magnetizable material. Alternatively, the holding member 12 may be formed of a magnetically permeable material, and the second magnet 22 may be disposed at a predetermined interval from the holding member 12.

  The magnetic pole on the holding member side of the second magnet 22 is preferably connected to the other end of the magnet rod constituting the first magnet 14 (the end not on the polishing object 1 side) with a yoke, As a result, the attractive force of the magnetic abrasive grains of the first magnet 14 can be increased.

  Similarly to the first magnet 14, the second magnet 22 can be moved in the direction facing the holding member 12 (Z direction) by moving means such as a moving screw or a sliding mechanism driven manually or by a motor. it can. The movement is controlled manually or automatically by a movement distance adjusting mechanism, and the interval between the second magnet 14 and the holding member 12 can be arbitrarily adjusted. Further, the moving distance adjustment mechanism may have a detection mechanism that detects the distance between the second magnet 22 and the surface 2 to be polished. This moving means may be omitted.

(Second driving means)
The second driving means 42 is means for relatively rotating the holding member 12 and the second magnet 22 within a virtual plane 2 a substantially parallel to the surface 2 to be polished. In particular, it is preferable that the second driving means 42 is appropriately synchronized with the movement of the first magnet 14 to give a time difference or operate asynchronously.

  The second magnet 22 is moved in a direction perpendicular to the direction facing the holding member 12, that is, a direction parallel to the holding surface of the holding member 12 (moving means such as a moving screw or a sliding mechanism driven manually or by a motor). X direction and Y direction). Such movement can be performed by an XY movement mechanism, and the second magnet 22 can be moved to a position facing the first magnet 14.

  The second magnet 22 is a second rotating mechanism such as a rotating mechanism that drives a gear directly attached to the second magnet 22 by a motor, or a rotating mechanism that drives a spindle connected to the holding member 12 via a gear mechanism. The driving means 42 can rotate the first magnet 14 with or without being synchronized.

(Other configurations)
In the case where an electromagnet is used as the first magnet 14 and / or the second magnet 22, the first magnet 14 and the second magnet 22 are synchronized or time difference is selected by appropriately selecting the magnetic pole conversion frequency of the electromagnet. Or can be asynchronous. By operating in this manner, the behavior mode of the magnetic abrasive grains being polished can be appropriately selected, and a desired polishing state can be obtained.

  In addition, when using a bundle of a plurality of electromagnets as the first magnet 14 and / or the second magnet 22, as in the above, by appropriately selecting the magnetic pole conversion frequency of the individual magnets constituting the bundled electromagnet, About the 1st magnet 14 and the 2nd magnet 22, it can synchronize for every individual magnet, can give a time difference, or can be made asynchronous. By operating in this manner, the behavior mode of the magnetic abrasive grains being polished can be appropriately selected, and a desired polishing state can be obtained.

  The magnetic-assisted fine polishing apparatus 10 of the present invention is a non-contact optical detection means (not shown in FIG. 1) that can place a portion to be polished located in the gap S between the polished surface 2 and the first magnet 14 in the field of view. ). Such non-contact optical detection means can detect optical characteristics such as reflectance or refractive index of the surface 2 to be polished, and as a result, it is also possible to specify the material forming the surface 2 to be polished.

  Moreover, it is preferable that the magnetic assistance fine polishing apparatus 10 of the present invention includes a control unit that compares the data acquired by the non-contact optical detection unit with a preset reference value. This control means compares (i) the three-dimensional relative positional relationship between the first magnet 14 and the polished surface 2 by comparing the data acquired by the non-contact optical detection means with a preset reference value. Adjustment and determination, (ii) Adjustment and determination of the three-dimensional relative positional relationship between the second magnet 22 and the polished surface 2, (iii) Determination of whether or not the polishing end point has been reached, and (iv) Continuation of polishing (V) Determination of stop of polishing, (vi) Adjustment of supply amount of magnetic abrasive grains, (vii) Operation mode, rotation speed, vibration for the first magnet 14, the second magnet 22 or the surface to be polished Various operation controls such as adjustment and determination of speed, amplitude, etc. can be performed. The magnetic-assisted fine polishing apparatus of the present invention is preferably provided with a comprehensive control system comprising such control means.

  Moreover, when the 2nd magnet 22 is provided, it is preferable to provide the position detection means which can detect or measure the three-dimensional relative positional relationship of the 2nd magnet 22 and the holding member 12. FIG. Such position detecting means may be mechanical, optical, or electrical. Further, in this case, it is preferable that a control unit that compares the data acquired from the position detection unit with a preset reference value is provided.

  As described above, according to the magnetic-assisted fine polishing apparatus or method of the present invention, the main force acting between the surface to be polished 2 and the abrasive grains is the individual magnetic abrasive magnetized on the first magnet 14. When the grains or chain-like magnetic abrasive grains move while being dragged and scraped on the surface to be polished 2 at a high speed in accordance with the relative movement of the first magnet 14 and the surface to be polished 2, they collide with the surface to be polished 2. It is characterized by an instantaneous impact force due to the mass and speed of each magnetic abrasive grain.

  The impact force at which each magnetic abrasive grain collides with the surface to be polished 2 is determined by the mass and hardness of the magnetic abrasive grains, the speed at the time of collision, etc., and the polishing speed is determined by the density of the magnetic abrasive grains causing the impact force. It is a function of the average of the impact force. The speed of the magnetic abrasive grains is determined by following the movement of the first magnet 14, and therefore depends on the strength of the binding force (magnetic attraction force) between the first magnet 14 and each magnetic abrasive grain. .

  Specifically, if the magnetic abrasive grains that gave an impact to the surface to be polished 2 have a binding force that does not detach once from the first magnet 14, the impact is successively applied at the moving speed of the first magnet 14. Therefore, the total impact force, that is, the polishing force is maximized. However, if the magnetic abrasive grains that have impacted the surface to be polished 2 are detached from the first magnet 14, the next magnetic abrasive grains on standby will magnetize the first magnet 14, and A time lag occurs when the moving speed is reached and the surface to be polished 2 is impacted. As a result, the total impact force decreases and the polishing force decreases. Therefore, it is desirable to have a strong magnetic attractive force that does not cause the magnetic abrasive grains to leave the first magnet 14, and the above-described improvement in the holding force by using the buff is also effective for this phenomenon.

  FIG. 5 is a block diagram showing an embodiment of the magnetic-assisted fine polishing apparatus of the present invention, which is an example of an apparatus for polishing a copper surface provided on a silicon wafer in a copper damascene wiring process of an integrated circuit manufacturing process. In addition, this invention is not limited to the example specifically shown below in the range which has the characteristic of the said invention.

  A magnetically assisted fine polishing apparatus 51 shown in FIG. 5 includes a wafer stage 52 on which a silicon wafer 1a is mounted, a vacuum supply system 56 provided at the lower center of the wafer stage 52, a wafer position moving stage 61, and a wafer position moving system. 62, a first magnet 67 provided at a position spaced from the silicon wafer 1a above the wafer stage 52, a first magnet rotating spindle 68, a first magnet rotating system 69, a first magnet A magnet vibration stage 70; a first magnet vibration system 71; a first magnet position movement stage 72; a first magnet position movement system 73; and a polishing slurry supply system 74. is doing.

  The wafer stage 52 includes a wafer mounting disk 53, a second magnet 55 provided with a slight gap immediately below the wafer mounting disk 53, and a cylindrical casing that wraps them. The wafer stage 52 may be provided with a device cover 78 for preventing the polishing slurry from scattering and a collection tray 79 for used slurry or surplus slurry.

  The wafer mounting disk 53 is made of a magnetically permeable material and has a diameter larger than that of the silicon wafer 1a that is an object to be polished. The wafer mounting disk 53 is provided with vacuum suction holes 54 at predetermined intervals, and the silicon wafer 1 a sucked by the vacuum suction holes 54 is mounted thereon. The vacuum suction holes 54 are a plurality of minute holes that penetrate the wafer mounting disk 53.

  The second magnet 55 is composed of an NdFeB permanent magnet having the same diameter as the wafer mounting disk 53. A vacuum introduction hole penetrating the second magnet 55 is provided in the outer edge portion of the second magnet 55, and the vacuum introduction hole communicates with the vacuum suction hole 54.

  The vacuum supply system 56 includes a vacuum pipe 57, an electromagnetic opening / closing valve 58, a vacuum release valve 59, and a vacuum pump 60 that are provided at the center lower portion of the wafer stage 52 and are connected to a vacuum inlet.

  The wafer position moving stage 61 is a stage that allows the wafer position moving system 62 to rotate or move the wafer stage 52 in an XY direction within a virtual plane substantially parallel to the surface to be polished. Further, the wafer position moving stage 61 can also adjust the inclination of the wafer surface to be polished.

  The wafer position moving system 62 includes a wafer stage rotating spindle 63 connected to the central axis of the wafer position moving stage 61, a horizontal moving screw 64 connected to appropriate horizontal positions in the X and Y directions, and a wafer position moving stage. There are stage inclination adjusting screws 65 provided at four corners 61 and a control motor 66 for operating them.

  The first magnet 67 is provided above the wafer stage 52 at a position separated from the silicon wafer 1a. The first magnet 67 is composed of a NdFeB permanent magnet having a polarity opposite to the magnetic pole of the second magnet 55 described above.

    The first magnet 67 is driven by a rotating spindle 68 having a holding mechanism for holding the first magnet at the tip, and a rotating system 69 that controls the rotation of the rotating spindle 68. The rotation system 69 performs start and stop of the motor, and setting and control of the rotation speed.

  The first magnet vibration stage 70 holds the rotary spindle 68 and the rotation system 69, and causes the first magnet 67 to linearly vibrate in the X or Y direction with a predetermined amplitude along the wafer polishing plane. It is a stage for elliptical vibration that vibrates simultaneously in both directions. The vibration stage 70 is linearly or elliptically vibrated by a vibration system 71 including a cam mechanism, a spring, a cam rotation motor, and the like connected to appropriate positions in the X and Y directions.

  A vibration stage 70 and a vibration system 71 are attached to the first magnet position moving stage 72, and the first magnet 67 is moved in the X direction, the Y direction, and the wafer polished along the wafer polished surface. Move in the Z direction perpendicular to the surface.

  The first magnet position moving system 73 is a system comprising a moving screw connected to an appropriate position in the X direction, Y direction and Z direction of the position moving stage 72 and a control motor for rotating the moving screw. .

  The polishing slurry supply system 74 is a system for supplying a polishing slurry containing magnetic abrasive grains to a polishing region on a silicon wafer 1a to be polished. A polishing slurry tank, a pump for sending the polishing slurry from the tank, a slurry It is composed of a transport pipe, a tip nozzle, a holder for holding the tip nozzle at the position of the polishing region, and the like.

  The magnetic-assisted fine polishing apparatus 51 is further preferably provided with a surface observation device 75 and a surface observation visual field moving system 76. The surface observation device 75 is a device for observing the surface state of the entire polished surface of the wafer, and the surface observation visual field moving system 76 is connected to the surface observation device 75 connected to appropriate positions in the X, Y, and Z directions. And a control motor for rotating the moving screw and the moving screw.

  Next, an operation example of the magnetic-assisted fine polishing apparatus 51 of the present invention will be described.

  (1) First, the surface to be polished of the silicon wafer 1a, which is an object to be polished, is placed on the wafer stage 52, and after starting the vacuum pump 60, the electromagnetic on-off valve 68 of the vacuum pipe 67 is opened, Adsorbed to the stage 52 and fixed. (2) Next, the wafer position moving stage 61 is moved by the wafer position moving system 62 to adjust the tilt of the silicon wafer 1a with respect to the first magnet 67, and the gap between the polished surface of the wafer and the tip of the first magnet 67 is adjusted. Is not changed by the movement of the silicon wafer 1 a or the first magnet 67. Further, the silicon wafer 1a is rotated or moved in the XY direction so that the first magnet 67 is adjusted to the initial position of wafer polishing. (3) Next, the first magnet position moving system 73 is moved up and down by the first magnet position moving system 73 so that the distance between the tip of the first magnet 67 and the surface to be polished is appropriate. Set the correct distance. (4) Next, the polishing slurry supply system 74 supplies an appropriate amount of polishing slurry containing magnetic abrasive grains into the gap between the polishing region on the silicon wafer 1a and the first magnet. (5) Next, the first magnet rotation system 69 rotates the first magnet 67 held at the tip of the rotation spindle 68 of the first magnet, and at the same time, the vibration system 71 of the first magnet. Thus, the first magnet 67 is vibrated with a preset amplitude and direction. (6) Next, in order to perform polishing with a predetermined thickness, polishing is performed by rotating and vibrating the first magnet 67 for a preset time. Thereafter, the first magnet position moving system 73 is used to move the first magnet position moving stage 72 in the X direction or the Y direction by a preset distance so that the tip of the first magnet 67 is moved onto the silicon wafer 1a. After adjusting so as to come to the next polishing position, the above-described work steps (4) to (6) are repeated.

  (7) Next, after finishing the above-described work steps (4) to (6) for the entire polishing region on the silicon wafer 1a, the first magnet rotation system 69 and the first magnet vibration system. 71 is stopped, the first magnet position moving system 73 is moved by the first magnet position moving system 73 to retract the first magnet 67 outside the wafer area, and the surface observation visual field moving system 77 is moved. The visual field of the surface observation device 76 is moved onto the silicon wafer 1a to observe the polished state of the entire surface of the wafer. (8) When a region of insufficient polishing is found as a result of wafer surface observation, the surface observation device 76 is retracted outside the wafer region by the surface observation visual field moving system 77, and the above-mentioned (4) ) To (8) are repeated. (9) Finally, after confirming that all the polishing regions on the silicon wafer 1a have been sufficiently polished, the electromagnetic on-off valve 68 of the vacuum pipe 57 is closed, and the electromagnetic on-off valve 68 of the vacuum pipe 57 is also on the terminal side. The vacuum release valve 59 provided in the above is opened, the silicon wafer 1a is removed from the wafer stage 52, and the polishing process is completed.

It is a typical block diagram which shows an example of the magnetic assistance fine polishing apparatus of this invention. It is a typical partial block diagram which shows another example of the magnetic assistance fine grinding | polishing apparatus of this invention. It is typical sectional drawing which shows an example of the abrasive | polishing material applied to this invention. It is typical sectional drawing which shows an example of the 1st magnet provided with the buff. It is a block diagram which shows embodiment of the magnetic assistance fine polishing apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Polishing object 1a Silicon wafer 2 Surface to be polished 2a Virtual plane 3 Holding surface 5 Abrasive material 10 Magnetic assistance fine polishing apparatus 12 Holding member 14 1st magnet 16 1st drive means 18 Abrasive material supply means 22 2nd magnet 24 Buff 26 Inclination Adjustment Mechanism 28 Fixing Tool 32 Magnetic Abrasive Grain 34 Plastic Ball 36 Diamond Fine Particle 38 Plating Film 42 Second Driving Means 51 Magnetic Assisted Fine Polishing Device 52 Wafer Stage 53 Wafer Mounted Disc 54 Vacuum Adsorption Hole 55 Second Magnet Disc 56 Vacuum supply system 57 Vacuum piping 58 Electromagnetic on-off valve 59 Vacuum release valve 60 Vacuum pump 61 Wafer position moving stage 62 Wafer position moving system 63 Wafer stage rotating spindle 64 Wafer stage horizontal moving screw 65 Wafer stage tilt adjusting screw 66 Control Mo 67 First magnet 68 First magnet rotation spindle 69 First magnet rotation system 70 First magnet vibration stage 71 First magnet vibration system 72 First magnet position moving stage 73 First magnet position moving system 74 Polishing slurry supply system 75 Tip nozzle 76 Surface observation device 77 Surface observation visual field moving system 78 Device cover 79 Recovery tray

Claims (9)

A holding member for holding an object to be polished;
A first magnet disposed opposite to the surface to be polished of the object to be polished held by the holding member and provided with a predetermined gap with the surface to be polished;
First driving means for relatively rotating and / or horizontally vibrating the holding member and the first magnet in a virtual plane substantially parallel to the surface to be polished;
A polishing material selected from magnetic abrasive grains, polishing abrasive grains containing magnetic particles, and magnetic abrasive grains or polishing slurry containing the polishing abrasive grains is supplied to the gap between the surface to be polished and the first magnet. A magnetic-assisted fine polishing apparatus comprising at least an abrasive supply means.   The magnetic-assisted fine polishing apparatus according to claim 1, further comprising a second magnet on an opposite side of the first magnet with the holding member interposed therebetween.   The second drive means for relatively rotating and / or horizontally vibrating the holding member and the second magnet in a virtual plane substantially parallel to the surface to be polished. Magnetic assisted fine polishing equipment.   2. A buff attached by an adhesive or a buff gripped by a magnetic force of the first magnet at a tip of the first magnet facing the surface to be polished. Magnetic assisted fine polishing apparatus according to any one of -3.   5. The magnetic-assisted fine polishing apparatus according to claim 4, wherein the buff is coated with an electroless plating film containing magnetic abrasive grains in a dispersed manner.   The magnetic-assisted fine polishing apparatus according to any one of claims 1 to 5, wherein the magnetic abrasive grains are formed by forming a magnetic plating film containing abrasive particles dispersed on the particle surface.   The magnetically assisted fine polishing apparatus according to any one of claims 1 to 6, wherein the object to be polished is a mixture of regions having different characteristics to be polished on the surface to be polished.   8. The magnetically assisted fine polishing apparatus according to claim 1, wherein the object to be polished is a wafer including a damascene structure of a metal wire layer or a solder paste printing mask for producing a printed wiring board. . A magnetic-assisted fine polishing method, which is performed using the magnetic-assisted fine polishing apparatus according to claim 1.

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