JP4601804B2 - Polishing wheel and method for manufacturing polishing wheel - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a polishing wheel and a polishing method, and more particularly to a polishing wheel suitable for polishing a surface of a semiconductor wafer. of The present invention relates to a manufacturing method and a polishing method.
[0002]
[Prior art]
In response to a demand for downsizing of an electronic circuit device, for example, as disclosed in Japanese Patent Application Laid-Open No. 2000-141215, an attempt is made to directly form an electronic circuit on a semiconductor bare chip. Here, by alternately forming insulating layers and wiring layers on the semiconductor chip, it is possible to form an electronic circuit in multiple layers.
[0003]
When manufacturing such an electronic circuit, for example, as disclosed in Japanese Patent Application Laid-Open No. 11-288906, the insulating layer formed on the semiconductor wafer is flattened, and the next layer is formed thereon. I am doing so. Here, a CMP (Chemical Mechanical Polishing) processing method is used for planarizing the surface of the insulating layer. In this processing method, the insulating layer formed on the surface of the semiconductor wafer is polished and flattened by a rotating polishing wheel, and high-precision flattening processing is performed.
[0004]
[Problems to be solved by the invention]
In the CMP process for planarizing the insulating layer on the surface of the semiconductor wafer as described above, polishing is performed while rotating and sliding a polishing wheel on the surface of the rotating semiconductor wafer while supplying slurry. Yes. Here, the polishing wheel in which the abrasive particles are held by a binder and the abrasive grains are fixed has a large number of pores formed on the surface, and these pores increase the unevenness of the wheel surface together with the abrasive grains to increase the polishing efficiency. I am doing so.
[0005]
Although such a polishing method can obtain high flatness, there is a drawback that the polishing ability changes according to wear of the wheel. In addition, there is a disadvantage that the polishing ability varies among the polishing wheels, and thus the polishing ability is not stable.
[0006]
This is because the fixed abrasive grains easily fall off from the wheel, and in order to maintain the polishing ability by maintaining the falling abrasive grains that are sequentially supplied to the abrasive grains and other pores, However, in practice, it is technically difficult to stably form the diameter and density of the pores.
[0007]
The present invention has been made in view of such problems, and while maintaining the advantages of the polishing wheel used in the CMP processing method and the like, while eliminating the disadvantages, high flatness is obtained and over a long period of time. Polishing wheel that demonstrates stable processing capability and maintains stable polishing performance with no variation between polishing wheels of An object is to provide a manufacturing method and a polishing method.
[0008]
[Means for Solving the Problems]
The invention of the present application is a method for manufacturing a polishing wheel used for CMP planarization of a semiconductor wafer, wherein a fiber sheet base material having a predetermined width is operated, and abrasive grains and a binder having a particle diameter of 0.01 to 10 μm Is applied to the surface of the sheet substrate to form an abrasive layer and a sheet substrate layer, and the thickness after forming the abrasive layer is 0.05-0. Winding a 3 mm sheet base material in a spiral shape. And A polishing surface is formed on the end surface that is orthogonal to the axial direction of the wound sheet base material and the end of the width direction of the sheet base material is exposed, and the polishing surface includes a sheet base material and an abrasive layer. A gap to hold loose abrasive grains is formed due to the difference in wear amount The present invention relates to a method of manufacturing a polishing wheel. In addition, it winds long in an axial direction here, and you may make it slice so that the dimension of an axial direction may become predetermined length after winding.
[0009]
Here, the sheet may be composed of a hydrophilic fiber sheet, and abrasive grains may be bonded and applied to the surface of the sheet with a bonding material. The hydrophilic fiber sheet is preferably a woven fabric, a nonwoven fabric, or a felt-like fibrous sheet. On the other hand, the abrasive grains applied to the sheet are one or more of silicon oxide, cerium oxide, aluminum oxide, manganese dioxide, iron oxide, zinc oxide, silicon carbide, boron carbide, and synthetic diamond. Is preferred.
[0012]
A main invention related to a polishing method is a polishing method for CMP flattening processing of a semiconductor wafer, wherein a fiber sheet base material having a predetermined width is operated, and abrasive grains and a binder having a particle diameter of 0.01 to 10 μm Is applied to the surface of the sheet substrate to form an abrasive layer and a sheet substrate layer, and the thickness after forming the abrasive layer is 0.05-0. A polishing surface is constituted by an end surface at which a side end portion in the width direction of the sheet substrate in a polishing wheel formed by winding a sheet substrate of 3 mm in a spiral shape is exposed. And, on the polishing surface of the polishing wheel, performing dressing to form a groove that is coarser than the thickness of the sheet base material after forming the abrasive grain layer, and after performing dressing, contact the semiconductor wafer while rotating the polishing wheel, Contains loose abrasive The present invention relates to a polishing method characterized by performing polishing while supplying a polishing liquid.
[0013]
Here, it is preferable that a groove is formed by a dresser on the polishing surface of the polishing wheel, and that the groove by the dresser is made rougher than the groove formed by the thickness of the spiral sheet of the polishing wheel. Moreover, it is suitable for use in a polishing method in which the workpiece is made of a semiconductor wafer and the insulating layer covering the conductor portion is polished. Alternatively, the workpiece may be made of a semiconductor wafer, and the conductor layer formed on the surface may be polished.
[0014]
The inventors of the present application have conducted extensive research on a polishing wheel that is capable of obtaining high flatness and maintaining stable processing performance over a long period of time. As a result, side end portions in the width direction of a spirally wound sheet are obtained. By making the exposed end surface the polishing surface of the polishing wheel, the fine structure of the polishing surface can be made substantially the same over time, and it has been found that stable polishing performance can be obtained, and the present invention has been achieved. Conventionally, the end surface where the side end in the width direction of the sheet is exposed has not been used as a polishing surface.
[0015]
That is, a preferred embodiment of the main invention of the present application is a polishing method in which a polishing wheel that holds fixed abrasive grains is rotated and slid while supplying free abrasive grains by slurry to a surface to be polished of a workpiece. In this polishing wheel, a polishing surface is constituted by an end surface at which side end portions in the width direction of one or more types of sheets are exposed, and the end surface is exposed in a spiral shape. It is a feature. And by making the end surface where the side edge of the width direction of the sheet is exposed as a polishing surface, the same polishing surface can be obtained from the same sheet, and even if the polishing surface is scraped, the inside is also the same polishing surface. Accordingly, a new polished surface is always created, and stable polishing performance can be obtained over a long period of time.
[0016]
In particular, the polishing wheel according to the invention of the present application is arranged such that the side end portion in the width direction of the sheet is exposed in a spiral shape or a spiral shape on the end surface constituting the polishing surface. Even if it carries out, the peeling between sheets which arises by the grinding | polishing resistance which a grinding wheel receives from a to-be-polished material at the time of grinding | polishing, ie, delamination can be prevented. On the other hand, when the laminated cut surface is simply a polished surface, delamination easily occurs due to polishing resistance and cannot be used stably as a polishing wheel.
[0017]
In such a polishing wheel, even if the polishing content is different between the surface and the inside of the sheet by applying a solution containing abrasive grains almost uniformly on the sheet constituting the polishing wheel, the width direction of the sheet The side edge of the sheet and the content of the abrasive grains on the surface and the inside of the sheet are almost the same, so even if the surface of the grinding wheel is scraped, an almost constant abrasive grain pattern can be used as the polishing surface. As a result, stable polishing performance can be obtained.
[0018]
In addition, according to such a grinding wheel, the cutting surface of the sheet having different physical properties such as hardness and porosity and the cutting surface of the sheet holding the fixed abrasive grains are regularly and alternately arranged in a spiral shape on the polishing surface. can do. And by selecting the thickness or dimension of each sheet to be used, the fine structure of the polishing functional site due to the physical properties of the side edges in the width direction of each sheet can be made constant, so there is no variation in polishing ability Stable polishing can be performed.
[0019]
In particular, according to a preferred aspect of the present invention, the polishing surface of the polishing wheel is arranged in a spiral shape on the side surface where one or more types of sheets are exposed in the width direction, and at least one type of the sheet holds fixed abrasive grains. Therefore, the fixed abrasive supply unit, the polishing unit, or the free abrasive holding unit can be caused to function in a minute portion of the polishing surface of the polishing wheel. Therefore, it is possible to perform polishing evenly while maintaining a high polishing rate and with few scratches. In addition, since the polishing wheel can be composed of a homogeneous sheet, high polishing performance can be maintained even when the polishing wheel is consumed by continuous processing, and there is little variation in polishing performance between the polishing wheels. The effect which can be processed is brought about.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
The polishing wheel and the polishing method of this embodiment are used for polishing an insulating film formed on the surface of a semiconductor wafer by a CMP processing method. That is, when a circuit is directly formed on the surface of the semiconductor wafer, an insulating layer is formed on the surface of the semiconductor wafer, and a wiring pattern is applied to the surface of the insulating layer. By repeating such a process for the number of layers, a circuit is directly formed on the surface of the semiconductor wafer.
[0021]
As shown in FIG. 1A, a conductor 12 constituting a wiring pattern is formed on the surface of a semiconductor wafer 11 by, for example, aluminum. An insulating film 13 is formed on the surface so as to cover the conductor 12. Here, the surface of the insulating film 13 is a convex portion in the portion where the conductor 12 is present, whereas the portion where the conductor 12 is not present is a concave portion, and the surface is uneven. Therefore, it is inappropriate to directly apply a conductor constituting the wiring pattern of the next layer on the surface of the insulating film 13. That is, as shown in FIG. 1B, it is necessary to planarize the surface of the insulating film 13, and for this purpose, a CMP processing method is used.
[0022]
FIG. 2 shows a CMP processing method, in which the semiconductor wafer 11 is held on the rotating disk 17. And the free abrasive grains are included from the slurry supply means 18 provided in the upper part of the rotating disk 17. It is polishing liquid Supply slurry. On the other hand, the grinding wheel 20 is attached to the attachment disc 19, and the rotating disk 17 and the attachment disc 19 are rotated separately.
[0023]
That is, here, the slurry supply means 18 supplies a slurry made of a polishing liquid containing free abrasive grains to the surface of the semiconductor wafer 11 while rotating the semiconductor wafer 11 mounted on the turntable 17 around the axis of the turntable 17. On the other hand, the hollow disc-shaped polishing wheel 20 is rotated around its axis by the mounting disc 19 to polish the surface of the semiconductor wafer 11. Here, the polishing wheel 20 is slid along the surface of the semiconductor wafer 11 as it rotates, and performs surface polishing with a predetermined pressing force.
[0024]
3 to 5 show a polishing wheel 20 used for the CMP processing of such a semiconductor wafer 11. 3 shows the overall appearance, FIG. 4 shows the surface of the grinding wheel 20, and FIG. 5 shows the bottom surface of the grinding wheel 20. That is, the polishing wheel 20 is disposed such that the end portion in the width direction of the sheet 24 is spirally exposed at the end surface constituting the polishing surface. The sheet used for the grinding wheel 20 may be anything as long as it has mechanical properties that can be wound in a spiral shape, and is not particularly limited. Further, the thickness of the sheet 24 to be used is about 0.05 to 1 mm, preferably about 0.1 to 0.3 mm.
[0025]
The direction of the spiral pattern formed by the sheet 24 of the polishing wheel 20 may be right-handed or left-handed. Any of both end faces in the axial direction of the polishing wheel 20 can be used as a polishing surface. Further, when such a polishing wheel 20 is used, the spiral pattern may be a direction in which the slurry is wound, or may be a direction in which the slurry is discharged. The selection is arbitrarily selected according to the winding direction of the sheet 24 formed on the wheel 20 and the rotation direction of the wheel 20.
[0026]
As the material of the sheet 24, a chemically synthesized fiber or inorganic fiber processed into a sheet shape in the state of woven fabric, nonwoven fabric, felt, or paper, an elastic polymer sheet, a sheet containing inorganic fine particles, or the like can be used. Moreover, although the kind of sheet | seat used here may be one type, it is preferable to use combining 2 or more types. It is particularly preferable to use a combination of an abrasive sheet holding fixed abrasive grains and a hydrophilic chemically synthesized fiber sheet.
[0027]
In particular, as the abrasive grain sheet 24 used in the present embodiment, the abrasive grains are impregnated or applied to the chemically synthesized fiber sheet 24 together with a binder made of a synthetic polymer, that is, a binder, and heated and dried to obtain fixed abrasive grains. It is preferable to hold it. As the abrasive grains impregnated or coated on the sheet, those having the same quality as the free abrasive grains used for the slurry during polishing are suitable. Specific examples of the fixed abrasive and the free abrasive include oxide, carbide, nitride, diamond and the like.
[0028]
Among these, examples of the oxide include silicon oxide, cerium oxide, aluminum oxide, manganese dioxide, iron oxide, and zinc oxide. In the case of carbide, silicon carbide, boron carbide and the like can be mentioned. In the case of nitride, cubic boron nitride or the like is used. In addition, natural or synthetic diamond is used. Moreover, the abrasive grain itself used may be a conventionally known one used for this kind of purpose, and is not particularly limited.
[0029]
Among such abrasive materials, it is preferable to select an abrasive material in consideration of the material of the material to be polished, polishing conditions, and compatibility with the material to be polished. As compatibility with the material to be polished, it is preferable to use a material having a hardness somewhat lower than the hardness of the material to be polished as the abrasive grains. For example, it is preferable to use cerium oxide as abrasive grains for processing a silicon oxide film and zinc oxide as abrasive grains for processing silicon.
[0030]
As the slurry for supplying the free abrasive grains, when the free abrasive grains are settling such as cerium oxide, an additive such as a surfactant is added to make the abrasive grains floating. In the case of abrasive grains such as silicon oxide, colloidal particles may be supplied.
[0031]
The particle diameter of the abrasive grains used is preferably within a range of 0.01 to 10 μm. If the particle diameter is within this range, it can be dispersed uniformly at a high density, but if the particle diameter exceeds 10 μm, it causes a fatal scratch.
[0032]
As a binder for dispersing abrasive grains, a polymer polymer such as polyacrylic, epoxy, or polyurethane is diluted with water or an organic solvent such as DMF (dimethylformamide) or DEF (diethylformamide). it can. The content of abrasive grains in the abrasive liquid is preferably 50 to 90% by weight.
[0033]
The polishing wheel 20 can be manufactured by winding the sheet 24 in a spiral shape while preferably applying or impregnating the binder with a binder. When the sheet 24 is wound, in order to strengthen the binding between the sheets, it is preferable to wind the sheet 24 while applying a synthetic polymer solution as a binder.
[0034]
As the synthetic polymer liquid used as the binder used here, a solvent solution or an aqueous emulsion of a thermosetting resin such as acrylic, epoxy, polyester, or urethane can be used. Alternatively, a thermoplastic resin may be used, and binding may be performed by heat sealing. In other words, the binder is not particularly limited as long as it is used in a concept including an adhesive and can attach the sheet 24.
[0035]
In addition to the function of binding between sheets, the above-mentioned binder has a function as a polishing region by controlling the coating thickness to be constant, and also has a function as an adjustment material for the elastic compressibility of the pad. You can also
[0036]
Here, the polishing wheel 20 can be formed by winding the sheet 24 in a state matching the size of each polishing wheel 20. Alternatively, the molded product formed in a cylindrical shape can be cut in a direction perpendicular to or crossing the axial direction, and the cutting end surface can be used as a polishing surface to form the polishing wheel 20 of the present embodiment. Further, the sheet 24 can be wound around a winding frame while being slit to the dimension in the thickness direction of the polishing wheel 20 to obtain a polishing wheel as it is.
[0037]
With the above structure, the polishing surface formed by the end face of the polishing wheel 20 holding the fixed abrasive grains has a portion holding the fixed abrasive grains and a polishing portion made of chemically synthesized fibers and chemically synthesized fibers as shown in FIGS. The pore portions of the sheet 24 can be repeatedly arranged in a spiral shape, and the polishing rate and flatness are set to predetermined values by providing the respective portions with functions of supplying fixed abrasives, polishing, and holding floating abrasive grains. It is possible to maintain high surface accuracy by reducing surface scratches.
[0038]
In addition, the polishing wheel 20 having such a configuration can homogenize the physical properties of the respective sheets 24 two-dimensionally using existing techniques. Such a sheet 24 is repeatedly arranged in a spiral shape to achieve three-dimensional homogenization, and even if the polishing wheel 20 is worn, a uniform polishing surface can be obtained, so that stable polishing performance can be obtained. .
[0039]
Further, since the thickness and homogenization of the sheet 24 are stably supplied even between the production lots, a polished surface with little variation can be obtained within the production lot of the polishing wheel 20 or between the production lots, and the stable polishing performance. Is obtained.
[0040]
By using the polishing wheel 20 as described above, the polishing performance is imparted by the abrasive grains filled in the base material constituting the wheel 20, and the base material of the wheel 20 has appropriate wear resistance. The surface of the wheel 20 is scraped little by little depending on the number of polishings, and polishing can be performed on a new surface.
[0041]
In addition, when such a polishing wheel is used, a stable quality polished surface can be obtained. If the abrasive-containing liquid is applied almost uniformly to the sheet 24, the abrasive content differs between the surface and the inside of the sheet. However, since the pattern of free abrasive grains contained in the cut end face of the sheet 24 and the surface and inside of the sheet 24 is substantially uniform, polishing can always be performed under constant polishing conditions.
[0042]
Note that the thickness of the abrasive grain layer 25 adhered to the sheet 24 can be adjusted by changing the squeezing ratio in a manufacturing apparatus described later. Therefore, as shown in FIG. 6 and FIG. It becomes a sheet base material layer The ratio of the relative thickness of the sheet 24 and the abrasive grain layer 25 can be arbitrarily adjusted. FIG. 6 shows a thick sheet 24 formed with a relatively thin abrasive layer 25. On the other hand, FIG. 7 shows the polishing wheel 20 when a thick abrasive grain layer 25 is formed on a thin sheet 24.
[0043]
Such a polishing wheel 20 is made of a CMP process used in the planarization process of the wafer 11 in the semiconductor wafer manufacturing process described above, or a glass substrate or an aluminum substrate that forms a master disk composed of a master disk such as a CD, DVD, or laser disk. Applied to surface processing. Alternatively, it can be applied to high-precision curved surface processing such as optical lenses and mold parts.
[0044]
For example, when used in the CMP processing method of the semiconductor wafer 11, the sheet 24 of the polishing wheel 20 is composed of a synthetic fiber sheet, particularly as shown in FIG. Abrasive Since it is softer than the layer 25, a minute space is formed between the abrasive grain layers 25 on the lower surface of the sheet 24 on the polishing surface where the side edges in the width direction of the sheet 24 are exposed, and slurry is supplied in such a space. The loose abrasive grains supplied by the means can be retained. By holding such loose abrasive grains, the CMP process can be stabilized.
[0045]
The laminated structure of the sheet 24 and the abrasive grain layer 25 constituting the polishing wheel 20 is not necessarily limited to the structure shown in FIG. 8, and a polymer film 26 and paper 27 may be further added between them. That is, as shown in FIG. 9, in addition to the sheet 24 and the abrasive layer 25, a thin polymer film 26 is further laminated to form three kinds of laminated structures. Alternatively, as shown in FIG. 10, a laminated structure of a sheet 24, an abrasive grain layer 25, and paper 27 may be used. Alternatively, as shown in FIG. 11, a laminated structure of a sheet 24, a polymer film 26, paper 27, and an abrasive layer 25 can be formed. Various other sheet-like materials can be appropriately laminated so that characteristics corresponding to the workpiece to be polished can be obtained.
[0046]
Next, an example of a manufacturing apparatus for manufacturing such a grinding wheel 20 will be described with reference to FIGS. As shown in FIG. It is a sheet base material The sheet 24 is supplied by a sheet supply roller 29. A motor 30 and a frequency generator 31 are coaxially attached to the supply roller 29. A tension roller 32 is disposed downstream of the sheet supply roller 29. A frequency generator 33 is attached to the tension roller 32. An abrasive bath 34 is disposed downstream of the tension roller 32. The abrasive bath 34 , Including binder A bath dissolved and dispersed in an organic solvent or the like, and provided with a pair of immersion rollers 35.
[0047]
A guide roller 36 is provided at a downstream outlet portion of the abrasive bath 34, and a pair of upper and lower squeezing rollers 37 and 38 are disposed on the downstream side of the guide roller 36. A frequency generator 39 is attached to one of the pair of squeezing rollers 37, 38, for example, the upper squeezing roller 37. A winding frame 40 is provided on the downstream side of the squeezing rollers 37 and 38, and a motor 41 and a frequency generator 42 are attached to the shaft.
[0048]
As shown in FIGS. 13 and 14, the winding frame 40 is provided with flanges 46 on both sides thereof, and the side ends of the sheet 24 wound by such flanges 46 are positioned. The flange 46 of the reel 40 is connected to a drive shaft 47, and the drive shaft 47 is rotatably supported by a pair of bearings 49 provided in a sleeve 48.
[0049]
Here, the frequency generators 31, 33, 39 and 42 shown in FIG. 12 are connected to the controller 43. The controller 43 controls the rotation of the motors 30 and 41.
[0050]
In such an apparatus, the sheet 24 fed from the sheet supply roller 29 is guided by the guide roller 32, and when passing through the abrasive bath 34, abrasive grains are applied or adhered to the surface thereof. Then, it reaches the squeezing roller 37 through the guide roller 36 and adjusts the amount of the abrasive liquid adhering thereto. And the sheet | seat 24 with which the appropriate quantity of abrasive liquid was apply | coated is wound up in the shape of a spiral by the winding frame 40, and the polishing wheel 20 is manufactured by this.
[0051]
In this apparatus, as shown in FIG. 14, the sheet 24 is wound in a state equal to the axial length of the polishing wheel 20, but the width of the sheet 24 is set to the width of the polishing wheel 20. A plurality of grinding wheels 20 can be created by setting the value to a sufficiently large value and slicing the sheet 24 after winding it in a spiral shape. Alternatively, the sheets supplied from the sheet supply roller 29 are slit in the middle so that the width of each sheet 24 is substantially equal to the value of the polishing wheel 20, thereby simultaneously winding a plurality of polishing wheels 20. Also good.
[0052]
As shown in FIG. 8, such a grinding wheel 20 has a different amount of wear when contacting the workpiece 11 between the soft sheet 24 portion and the hard abrasive grain layer 25 portion. A minute gap is generated in the part. Accordingly, the loose abrasive grains can be held by such a gap.
[0053]
More preferably, as shown in FIGS. 15 and 16, the polishing surface of the polishing wheel 20 is dressed by a dresser 52, whereby a dresser groove 53 having a twill pattern is formed on the polishing surface of the polishing wheel 20 as shown in FIG. You may make it form. It is desirable to set the size of the dresser groove 53 to a value larger than that of the minute concave portion 54 formed at the side end portion of the sheet 24. As a result, as shown in FIG. In addition, a large dresser groove 53 can be formed between the plurality of recesses 54.
[0054]
Next, an apparatus for performing CMP processing on the semiconductor wafer 11 using such a polishing wheel 20 will be described with reference to FIG. This apparatus includes a gantry 57, and a base 58 is mounted on the gantry 57. On the base 58, a Y-axis table 59 and an X-axis table 60 are placed. The Y-axis table 59 is fed in the Y-axis direction by a Y-axis ball screw 61, and a Y-axis actuator 62 for driving the Y-axis ball screw 61 is provided. The X-axis table 60 is fed by an X-axis ball screw 63, and the ball screw 63 is driven by an X-axis actuator 64. A turntable 66 is further mounted on the X-axis table 60 via a rotary actuator 65. The semiconductor wafer 11 is placed on the turntable 66.
[0055]
A column 70 is erected on the mount 57. A Z-axis guide 71 is attached to the column 70, and a spindle motor 73 is supported by an arm 72 provided on the Z-axis guide 71. The spindle motor 73 supports a mounting disc 74 on its output shaft. A Z-axis ball screw 75 is arranged in parallel with the Z-axis guide 71, and a Z-axis actuator 76 for driving the ball screw 75 is provided. A controller 80 is provided to drive and control the Y-axis actuator 62, the X-axis actuator 64, the rotation actuator 65, the spindle motor 73, and the Z-axis actuator 76.
[0056]
In the configuration as described above, the semiconductor wafer 11 is placed on the turntable 66. The turntable 66 is moved in the X-axis direction by the X-axis actuator 64 and the X-axis ball screw 63, and is moved in the Y-axis direction by the Y-axis actuator 62 and the Y-axis ball screw 61. On the other hand, the spindle motor 73 is moved up and down by the Z-axis guide 71 by the Z-axis actuator 76 and the Z-axis ball screw 75. A mounting disc 74 attached to the output shaft of the spindle motor 73 is rotated by the spindle motor 73. Accordingly, by attaching the polishing wheel 20 to the mounting disk 74, the semiconductor wafer 11 on the turntable 66 is polished by such a polishing wheel 20.
[0057]
【Example】
Next, examples of the present invention will be described. In addition, this invention is not limited by such an Example.
[0058]
Example 1
(Polishing wheel)
The grinding wheels were divided into production lots, and 2 lots per lot, 10 in total, and 10 grinding wheels were arbitrarily extracted from each lot, and the grinding results were compared. For convenience of explanation, the grinding wheels extracted from each lot are referred to as (1) and (2). The production specifications of the grinding wheel and the hardness of the grinding wheel produced are shown below.
[0059]
(Production specification of grinding wheel)
An aqueous abrasive solution was prepared by uniformly dispersing cerium oxide having an average particle size of 1.0 μm and a purity of 99.9% in an aqueous methyl methacrylate solution. Such an abrasive liquid is roll-formed while being applied between two spunbonded PET non-woven fabrics having a width of 200 mm and a basis weight of 20 g / m @ 2, and dried by heating to cure methyl methacrylate, and a thickness of 0. A sheet containing 3 mm inorganic fine particles was prepared. The basis weight of the obtained sheet was 600 g / m @ 2, and the cerium oxide content in the sheet was 79% by weight.
[0060]
The sheet containing the fine particles is coated on the transfer roll with the aqueous methyl methacrylate solution, wound to a diameter of 200 mm while being pressed with a touch roll, sliced after being dried by heating, cured, and thereby sliced into a diameter of 200 mm × width. A polishing wheel 20 of 20 mm × thickness 20 mm was prepared.
[0061]
(Hardness of polishing wheel)
The hardness of the grinding wheels (1) and (2) prepared as described above was as follows.
[0062]
Hardness of grinding wheel (1): ASKER C-type hardness meter 97 degrees
Hardness of grinding wheel (2): ASKER C-type hardness meter 98 degrees
Using the polishing wheels (1) and (2), as shown in FIG. 1, a material to be polished on which an insulating film 13 made of silicon oxide having a thickness of 10,000 angstrom was formed on a semiconductor wafer 11 having a diameter of 8 inches was continuously polished.
[0063]
(slurry)
Free abrasive grains: CeO2 (purity 90%, average particle size 0.5 .mu.m, bulk specific gravity 6.5 g, specific surface area 1-2 m @ 2)
Additive: Surfactant
Volume mixing ratio: 2 water to 1 cerium oxide powder to 1 additive
Mixture supply amount: 40 ml / min
As a result of continuous polishing under the above conditions, it was confirmed that both the polishing wheels (1) and (2) are within the following polishing performance range and have stable polishing performance with no variation.
[0064]
Polishing rate: 3500 ± 5% angstrom / min
Residual film thickness accuracy after polishing at 7000 Å: ± 400 Å
Flatness: 0 angstrom with removal amount twice the initial step
As yet another embodiment of the present invention, two-stage polishing can be performed by changing the material of the polishing wheel 20 and the abrasive grains. This is effective for the purpose of obtaining high surface properties simultaneously with flatness.
[0065]
That is, the primary processing increases the amount of polishing, removes the level difference and unevenness on the surface to improve the flatness, and then increases the surface property by secondary processing of a small amount of polishing. In the primary processing, a slightly harder grinding wheel is used together with abrasive grains having a hardness and particle size that can be polished relatively efficiently. In the secondary processing, in order to enhance the surface property, the hardness and particle size of the micro-scratch can be suppressed. Abrasive grains and a relatively soft polishing wheel are used.
[0066]
In this case, it is extremely effective to use a polishing method using both the fixed abrasive processing and free abrasive processing of the present invention for both primary processing and secondary processing. By such two-stage processing, a polished surface having extremely high flatness and surface property can be obtained efficiently in a short time, and the total tact time can be reduced.
[0067]
Since the polishing wheel 20 used here has a side edge of the sheet 24 as a polishing surface, the same polishing surface can be obtained from the sheet 24 having the same polishing function, and the inside is the same even if the polishing surface is scraped. Since it is a polished surface, stable polishing performance can be obtained. Further, when the surface of the sheet is a polished surface, the fibers are rubbed in the length direction of the fibers, so that the fibers are easily removed. Contrary to this, since the end surface where the side edge in the width direction of the sheet is exposed is used as a polishing surface, the end surface of the fiber is not rubbed, and the fiber does not come out even if it is worn away. Performance is obtained. Further, in the polishing wheel 20 used here, the cut surface of the sheet 24 is arranged in a spiral shape. By doing so, the delamination of the sheet 24 can be achieved even if the end surface constituting the polishing surface is vigorously polished. Will not occur.
[0068]
Although the invention included in the present application has been described above with reference to the embodiments and examples, the invention of the present application is not limited by these examples and embodiments, and various modifications are possible within the scope of the technical idea of the present invention. It can be changed.
[0069]
For example, the above embodiment relates to the polishing of the insulating layer covering the conductor portion on the surface of the semiconductor wafer, but it is also possible to polish the conductor layer instead of the insulating layer.
[0070]
When polishing the conductor layer, a groove for wiring is formed in the insulating film formed on the surface of the semiconductor wafer, and the conductor layer is formed by a method such as plating so as to fill the groove and cover the surface of the insulating layer. Form. Then, by polishing the surface of the conductor layer in the same manner as in the above embodiment, only the conductor in the wiring groove remains, thereby forming the wiring.
[0071]
【The invention's effect】
Grinding wheel Is The sheet coated with abrasive grains is wound in a spiral shape, and the polishing surface is constituted by the end surface at which the side end in the width direction of the sheet is exposed.
[0072]
Therefore, according to such a polishing wheel, even if the polishing surface is scraped and worn, the same internal polishing surface can be created one after another, thereby obtaining stable polishing performance. In addition, since the end surface where the side end in the width direction of the sheet is exposed is used as the polishing surface, the sheet does not cause delamination during polishing.
[0073]
The main invention related to the manufacturing method of the grinding wheel is: A method for manufacturing a polishing wheel used for CMP planarization of a semiconductor wafer, Of a given width Fiber sheet base material , The particle size is 0.01 to 10 μm Abrasive When Binder Mixed with Sheet by passing through solution bath Base material Apply abrasive grains to the surface of The thickness after forming an abrasive grain layer and a sheet base material layer, and forming an abrasive grain layer is 0.05-0.3 mm Sheet Base material Is wound in a spiral shape.
[0074]
Therefore, according to such a method for manufacturing a polishing wheel, it is possible to efficiently and easily manufacture a polishing wheel that forms a polishing surface by an end surface at which the side end portion in the width direction of the sheet is exposed.
[Brief description of the drawings]
FIG. 1 is an enlarged longitudinal sectional view of a main part of a semiconductor wafer.
FIG. 2 is a front view showing a CMP processing method for a semiconductor wafer.
FIG. 3 is a perspective view of a polishing wheel.
FIG. 4 is a plan view of the grinding wheel.
FIG. 5 is a bottom view of the polishing wheel.
FIG. 6 is a plan view of a polishing wheel in which the thickness of the sheet is increased with respect to the abrasive layer.
FIG. 7 is a plan view of a polishing wheel in which the thickness of the sheet is reduced with respect to the abrasive layer.
FIG. 8 is an enlarged longitudinal sectional view of a polishing wheel.
FIG. 9 is an enlarged longitudinal sectional view of a main part of a polishing wheel according to another embodiment.
FIG. 10 is an enlarged longitudinal sectional view of a main part of a polishing wheel according to still another embodiment.
FIG. 11 is an enlarged longitudinal sectional view of a main part of a polishing wheel according to still another embodiment.
FIG. 12 is a block diagram showing a method for manufacturing a polishing wheel.
FIG. 13 is a side sectional view of a winding portion of a polishing wheel.
FIG. 14 is a longitudinal sectional view of a winding portion of a polishing wheel.
FIG. 15 is a bottom view showing dressing of the grinding wheel.
FIG. 16 is a longitudinal sectional view showing dressing of the grinding wheel.
FIG. 17 is an enlarged longitudinal sectional view of a main part of a polishing surface of a polishing wheel subjected to dressing.
FIG. 18 is a block diagram of a polishing apparatus for CMP processing of a semiconductor wafer.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Semiconductor wafer, 12 ... Conductor (wiring pattern), 13 ... Insulating layer, 17 ... Turning board, 18 ... Slurry supply means, 19 ... Mounting disk, 20 ... Polishing wheel, 24 ... Sheet, 25 ... Abrasive layer (coating layer), 26 ... Polymer film, 27 ... Paper, 29 ... Sheet supply roller, 30 ... Motor, 31 ... Frequency generator, 32 ... Tension roller, 33 ... Frequency generator, 34 ... Abrasive bath, 35 ... Immersion roller, 36 ... Guide roller, 37, 38 ... Squeeze roller, 39 ... Frequency generator, 40 ... Reel, 41 ... Motor, 42 ... Frequency generator, 43 ... Controller, 46 ... Flange, 47 ... Drive shaft, 48 ... Sleeve, 49 ... Bearing, 52 ... Dresser, 53 ... Dresser groove, 54 ... Recess , 57 ... Frame, 58 ... 59 ... Y-axis table, 60 ... X-axis table, 61 ... Y-axis ball screw, 62 ... Y-axis actuator, 63 ... X-axis ball screw, 64 ... X-axis actuator, 65 ... Rotation actuator, 66 ... Turntable, 70 ... Column, 71 ... Z-axis guide, 72 ... Arm, 73 ... Spindle motor, 74 ... Mounting disc, 75 ... Z-axis ball screw, 76 ... Z-axis actuator, 80 controller

Claims (2)

A method for manufacturing a polishing wheel used for CMP planarization of a semiconductor wafer,
A fiber sheet base material having a predetermined width is manipulated, and the abrasive grains are applied to the surface of the sheet base material by passing through a mixed solution bath of abrasive grains and a binder having a particle diameter of 0.01 to 10 μm. Forming an abrasive layer and a sheet base layer,
Winding the sheet base material having a thickness of 0.05 to 0.3 mm after forming the abrasive layer, spirally wound,
A polishing surface is formed on the end surface that is orthogonal to the axial direction of the wound sheet base material and the end of the width direction of the sheet base material is exposed,
A method for manufacturing a polishing wheel, wherein a gap for holding free abrasive grains is formed on the polishing surface by a difference in wear amount between the sheet base material and the abrasive grain layer . A polishing method for CMP planarization of a semiconductor wafer,
A fiber sheet base material having a predetermined width is manipulated, and the abrasive grains are applied to the surface of the sheet base material by passing through a mixed solution bath of abrasive grains and a binder having a particle diameter of 0.01 to 10 μm. Polishing is formed by forming an abrasive layer and a sheet base layer, and winding the sheet base having a thickness of 0.05 to 0.3 mm after the formation of the abrasive layer into a spiral shape. A polishing surface is constituted by an end surface at which a side end portion in the width direction of the sheet base material in the wheel is exposed,
On the polishing surface of the polishing wheel, dressing is performed to form a groove that is coarser than the thickness of the sheet base material after forming the abrasive grain layer,
A polishing method comprising: performing polishing while contacting the semiconductor wafer while rotating the polishing wheel and supplying a polishing liquid containing free abrasive grains after the dressing.

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