JP4837853B2 - Grinding wheel - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to, but is not limited to, a grinding wheel that is advantageously used to grind one side of a semiconductor wafer.
[0002]
[Prior art]
As is well known to those skilled in the art, in the manufacture of semiconductor devices, single-side grinding is performed to grind one side of a semiconductor wafer so that the semiconductor wafer has a required thickness. For such grinding, a grinding machine including a chuck table having a flat holding surface and a rotating shaft disposed to face the chuck table is used. The semiconductor wafer is held on the chuck table with its one surface to be ground exposed (hence, the opposite surface is in close contact with the chuck table), and a grinding wheel is mounted on the tip of the rotating shaft. The grinding wheel is composed of an annular base and grindstone means mounted on the lower surface of the base. The grindstone means is usually composed of a plurality of grindstones that are arranged at intervals in the circumferential direction and extend in an arc shape in the circumferential direction. A plurality of coolant flow holes are formed in the base at intervals in the circumferential direction. Each of the coolant flow holes extends through the base from the upper surface to the lower surface of the base, and the lower end thereof is positioned radially inward of the grindstone means attached to the lower surface of the base. The chuck table is rotated at a relatively low speed (for example, 100 to 300 rpm), the rotating shaft and the grinding wheel attached thereto are rotated at a relatively high speed (for example, 4000 to 5000 rpm), and the grinding wheel means of the grinding wheel is a semiconductor. Grinding of one side of the semiconductor wafer is performed by pressing against one side of the wafer and moving it forward. In such grinding, a coolant such as pure water is supplied to the coolant flow hole of the grinding wheel through the coolant flow path disposed on the rotating shaft, and the coolant flowing in the bottom surface of the base is opened. Coolant flows out of the hole.
[0003]
[Problems to be solved by the invention]
Thus, according to the inventor's experience, in the grinding using the conventional grinding wheel of the above-described form, the supplied coolant is used for the grinding wheel means of the grinding wheel and the grinding surface of the object to be ground, that is, the semiconductor wafer. It has been found that the grinding efficiency is not necessarily sufficient due to the fact that the grinding efficiency is not sufficient due to the fact that the grinding wheel is not sufficiently effective for cooling, and that the grinding wheel means in the grinding wheel is relatively worn.
[0004]
The present invention has been made in view of the above-mentioned facts, and the main technical problem thereof is to improve the grinding wheel and use the supplied coolant sufficiently effectively for cooling the grinding wheel and the object to be ground. Is to do so.
[0005]
[Means for Solving the Problems]
In Japanese Patent Application No. 2001-203115 (name of invention: grinding wheel) according to the applicant's application, the shape of the base of the grinding wheel is improved, and more specifically, radially inward of the inner periphery of the base. An open coolant reservoir is formed and the coolant supplied to the grinding wheel base is prevented from flowing radially outward by the coolant reservoir and then overflows toward the grinding wheel means and the object to be ground. It is disclosed that the supplied cooling liquid can be effectively used for cooling the grinding wheel and the workpiece to be ground. The inventor further improves the grinding wheel, that is, grinds the supplied coolant by forming a plurality of coolant guide grooves extending from the coolant reservoir to the grinding wheel means at intervals in the circumferential direction. It has been found that it can be used more effectively for cooling wheels and workpieces.
[0006]
That is, according to the present invention, as a grinding wheel that achieves the main technical problem, a plurality of annular bases and a plurality of circumferentially spaced apart circumferential bases are provided on the lower surface of the bases . In a grinding wheel composed of a grinding wheel means composed of a grinding wheel,
A cooling liquid reservoir that is opened radially inward is formed on the inner periphery of the base, and the inner peripheral surface and the lower surface of the base are spaced apart in the circumferential direction and each of the grindstones. Correspondingly, there is provided a grinding wheel characterized in that a plurality of cooling liquid guide grooves extending in the direction of rotation of the grinding wheel are formed from the cooling liquid reservoir toward the grindstone .
[0007]
It is preferable that the downstream end of the coolant guide groove continues to the inner peripheral surface of the grindstone on the upstream side of the middle of the grindstone as viewed in the rotation direction of the grinding wheel . In a preferred embodiment, the cooling liquid reservoir is continuously extended in the circumferential direction. The cooling liquid reservoir inclines downward and extends outward in the radial direction and inclines downward below the upper inclined surface substantially horizontally inward in the radial direction or downward inward in the radial direction. It is defined between the projecting surfaces that extend. A plurality of communication cutouts or communication holes communicating with the coolant reservoir from the upper surface are formed in the base at intervals in the circumferential direction. The base has a lower inclined surface extending downward and inclined radially outward below the projecting surface.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, with reference to the accompanying drawings, a preferred embodiment of a grinding wheel constructed according to the present invention will be described in more detail.
[0009]
Referring to FIGS. 1 and 2, the grinding wheel denoted as a whole by the number 2 is composed of a base 4 and a grindstone means 6. The base 2 which can be formed from a suitable metal such as aluminum is generally annular, an annular upper surface 8 which is substantially horizontal, an annular lower surface 10 which is substantially horizontal and a cylindrical outer peripheral surface which is substantially vertical. Twelve.
[0010]
It is important that a cooling liquid reservoir 14 opened radially inward is formed on the inner periphery of the base 4. In the illustrated embodiment, the inner peripheral surface of the base 4 has an upper hanging surface 16 that extends substantially vertically downward, a receding surface 18 that extends radially outward from a lower end of the upper hanging surface 16, and a receding surface. An upper inclined surface 20 extending obliquely outward in the radial direction downward from the radially outer end of the surface 18, an intermediate hanging surface 22 extending substantially vertically downward from the lower end of the upper inclined surface 20, and the intermediate hanging surface 22 A projecting surface 24 extending downwardly from the lower end of the upper inclined surface 20, and thus downwardly inward in the radial direction, and a lower hanging surface extending substantially vertically downward from the radially inner end of the projecting surface 24. 26, and a lower inclined surface 28 extending from the lower end of the lower drooping surface 26 to be inclined downward in the radial direction downward. And between the upper inclined surface 20 and the protrusion surface 24, the cooling liquid reservoir 14 whose cross-sectional shape is a substantially right triangle shape is prescribed | regulated. The upper hanging surface 16, the retreating surface 18, the upper inclined surface 20, the intermediate hanging surface 22, the projecting surface 24, the lower hanging surface 26, and the lower inclined surface 28 are arranged in the circumferential direction except for a portion where a communication notch described later is formed. The cooling liquid reservoir 14 is also continuously extended in the circumferential direction. The cooling liquid reservoir 14 does not necessarily have to be continuously extended in the circumferential direction, and a plurality of cooling liquid reservoirs extending in the circumferential direction with intervals in the circumferential direction can be formed if desired. The inclination angle α of the upper inclined surface 20 may be about 10 to 30 degrees. The inclination angle β of the lower inclined surface 28 may be about 35 to 55 degrees. The inclination angle γ of the protruding surface 24 may be 0 (that is, it extends substantially horizontally) to about 20 degrees.
[0011]
A plurality of coolant guide grooves 62 extending from the coolant reservoir 14 to the grindstone means 6 are provided on the lower surface 10 together with the lower hanging surface 26 and the lower inclined surface 28 on the inner peripheral surface of the base 4. It is important that it is formed . As will be further described later , the grindstone means 6 is composed of a plurality of grindstones 36 that are arranged at intervals in the circumferential direction and extend in an arc shape in the circumferential direction, and each of the coolant guide grooves 62 is provided in each grindstone 36. Correspondingly formed. Each of the coolant guide grooves 62 extends incline in one circumferential direction, that is, the rotational direction of the grinding wheel 2 as understood by referring to FIG. to eliminate the flow trend in the circumferential direction Ru allowed reduction. Further, it is preferable that the downstream end of each coolant guide groove 62 continues to the inner peripheral surface of the grindstone 36 on the upstream side of the middle of each grindstone 36 when viewed in the rotation direction of the grinding wheel 2. The inclination angle θ of the coolant guide groove 62 in one circumferential direction may be about 20 to 60 degrees.
[0012]
As clearly understood by referring to FIG. 1, the base 4 has a plurality of communication cutouts 30 extending from the upper surface 8 to the receding surface 18 on the inner peripheral surface at intervals in the circumferential direction. Six pieces are formed at an angular interval, and the upper surface of the base 4 is communicated with the cooling liquid reservoir 14 through a communication notch 30. Each of the communication cutouts 30 has a substantially semicircular shape, and the inside in the radial direction is open. If desired, instead of the communication notch 30, a communication hole having an appropriate cross-sectional shape such as a circular shape that is also closed on the radially inner side may be formed. The base 4 further includes a plurality of blind screw holes 32 extending substantially vertically downward from the upper surface 8 at intervals in the circumferential direction. In the illustrated embodiment, six blind screw holes 32 are formed at equal angular intervals, and each of the blind screw holes 32 is positioned in the middle of the adjacent communication notch 30 when viewed in the circumferential direction. Yes.
[0013]
Continuing with reference to FIGS. 1 and 2, the grindstone means 6 is disposed on the lower surface 10 of the base 4. More specifically, in the illustrated embodiment, an annular groove 34 extending continuously in the circumferential direction is formed on the lower surface of the base 10. The grindstone means 6 is composed of a plurality (27 in the illustrated case) of grindstones 36 extending in an arc shape in the circumferential direction with an interval in the circumferential direction, and each of the grindstones 36 is grooved in the upper part by an appropriate adhesive. It is fixed to the lower surface of the base 10 by being fixed in the interior 34. Each of the grindstones 36 may be formed by, for example, bonding diamond abrasive grains with an appropriate binder such as vitrified. Each cross-sectional shape of the grindstone 36 is rectangular .
[0014]
FIG. 4 schematically illustrates a manner in which one side of the semiconductor wafer 38 is ground using the grinding wheel 2 illustrated in FIGS. 1 and 2. The semiconductor wafer 38 to be ground on one side is held on the chuck table 40 with the one side to be ground exposed upward. It is preferable that the chuck table 40 has a configuration in which at least a central main portion is formed of a porous material or has a plurality of suction holes so that the semiconductor wafer 38 can be vacuum-sucked.
[0015]
A rotating shaft 42 is disposed above the chuck table 40, and the grinding wheel 2 is attached to the tip, that is, the lower end of the rotating shaft 42. More specifically, a mounting flange 44 is integrally formed at the lower end of the rotating shaft 42, and a circular recess 46 having a relatively large diameter is formed on the lower surface of the mounting flange 44. The rotating shaft 42 is formed with a coolant flow path 48 that extends in the vertical direction and opens into a circular recess 46. An additional member 50 is fixed to the lower end of the rotating shaft 42, and thus to the mounting flange 44. The additional member 50 has an upper portion having an outer diameter substantially the same as the inner diameter of the circular recess 46 and a lower portion having an outer diameter substantially the same as the outer diameter of the mounting flange 44, and the upper portion is inserted into the circular recess 46. The annular shoulder surface defined between the upper part and the lower part is brought into contact with the lower surface of the mounting flange 44. A through hole extending in the radial direction from the outer peripheral surface to the circular recess 46 is formed in the mounting flange 44 at intervals in the circumferential direction, and a blind screw hole extending in the radial direction from the outer peripheral surface is formed in the upper portion of the additional member 50. Are formed at intervals in the circumferential direction, and the additional member 50 is fixed to the mounting flange 44 by screwing the fastening bolt 51 into the blind screw hole of the additional member 50 through the through hole of the mounting flange 44. A sealing ring 52, which may be made of synthetic rubber, is disposed between the upper outer peripheral surface of the additional member 50 and the inner peripheral surface of the circular recess 46 of the mounting flange 44, and the annular shoulder surface of the additional member 50 and the mounting flange 44. A sealing ring 54, which may be made of synthetic rubber, is also disposed between the lower surface. The upper surface of the additional member 50 is formed with a plurality of (six in the figure) grooves 56 extending radially from the center thereof, and also extends substantially vertically from the outer end of each of the grooves 56 and opens to the lower surface. A hole 58 is formed. The groove 56 and the hole 58 are communicated with the coolant channel 48 formed in the rotating shaft 42.
[0016]
When the description is continued with reference to FIG. 4 together with FIGS. 1 and 2, the grinding wheel 2 is mounted on the lower surface of the additional member 50. The mounting flange 44 and the additional member 50 are formed with a plurality of (six in the illustrated example) through-holes extending substantially vertically at intervals in the circumferential direction. Through this through hole, the fastening bolt 60 is screwed into the blind screw hole 32 formed on the upper surface of the base 4 of the grinding wheel 2, thereby grinding the lower surface of the additional member 50 and hence the lower end of the rotating shaft 44. Wheel 2 is mounted. Each of the communication notches 30 formed on the base 4 of the grinding wheel 2 is aligned with each of the holes 58 formed in the additional member 50. Therefore, the cooling liquid reservoir 14 formed on the base 4 of the grinding wheel 2 passes through the communication notch 30 formed in the base 4 and the hole 58 and the groove 56 formed in the additional member 50. The cooling fluid channel 48 formed in the rotating shaft 44 is communicated.
[0017]
When grinding one side of the semiconductor wafer 38, the chuck table 40 is rotated at a relatively low speed, which may be about 100 to 300 rpm, and the rotary shaft 44 is rotated at a relatively high speed, which may be about 4000 to 5000 rpm. Then, the grinding wheel 2 is pressed against one surface of the semiconductor wafer 38 to be processed gradually, and thus one surface of the semiconductor wafer 38 is ground by the grinding wheel 2, more specifically by the grindstone means 6. During such grinding, a coolant that is pure water at room temperature is supplied through the coolant channel 48 of the rotating shaft 44. The coolant flows from the coolant channel 48 of the rotating shaft 44 through the groove 56 and the hole 58 formed in the additional member 50, and then passes through the communication notch 30 formed in the base 4 of the grinding wheel 2. Into the coolant reservoir 14. Since the grinding wheel 2 is rotated at a relatively high speed, a considerable centrifugal force acts on the coolant, thereby causing the coolant to flow radially outward. However, in the grinding wheel 2 configured according to the present invention, the cooling liquid reservoir 14 opened radially inward is disposed, so that the cooling liquid having a tendency to flow radially outward is once cooled. The liquid is retained in the liquid reservoir 14 and the outward flow in the radial direction is suppressed. Then, after being retained in the coolant reservoir 14, it flows out of the coolant reservoir 14 mainly through the coolant guide groove 62, and is guided onto the grindstone means 6 and one surface of the semiconductor wafer 38 being ground thereby. In the grinding wheel 2 configured according to the present invention, the coolant that is caused to flow radially outward due to the high-speed rotation of the grinding wheel 2 is once retained in the coolant reservoir 14, so that a required portion, that is, grinding is performed. Since the cooling liquid is supplied to the portion where it is performed, it is prevented or suppressed that the cooling liquid is caused to flow excessively outward in the radial direction and is wasted, and the cooling liquid is used sufficiently effectively.
[0018]
【The invention's effect】
In the grinding wheel of the present invention, the supplied coolant is sufficiently effectively used for cooling the grinding wheel and the object to be ground, so that the abrasion of the grindstone is reduced and the grinding ratio is improved.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a preferred embodiment of a grinding wheel constructed according to the present invention, with a part cut away.
2 is a partially enlarged sectional view of the grinding wheel shown in FIG.
FIG. 3 is a partial perspective view showing a part of the grinding wheel shown in FIG. 1;
4 is a cross-sectional view illustrating a manner in which one side of a semiconductor wafer is ground using the grinding wheel shown in FIG. 1;
[Explanation of symbols]
2: Grinding wheel 4: Base 6: Grinding wheel means 14: Coolant reservoir 20: Upper inclined surface 24: Protruding surface 30: Communication notch 36: Grinding stone 62: Coolant guide groove

Claims (6)

In a grinding wheel composed of an annular base and a grindstone means composed of a plurality of grindstones arranged at intervals in the circumferential direction on the lower surface of the base and extending in an arc shape in the circumferential direction ,
A cooling liquid reservoir that is opened radially inward is formed on the inner periphery of the base, and the inner peripheral surface and the lower surface of the base are spaced apart in the circumferential direction and each of the grindstones. Correspondingly, a plurality of cooling liquid guide grooves extending obliquely in the rotation direction of the grinding wheel from the cooling liquid reservoir toward the grinding wheel are formed . The grinding wheel according to claim 1, wherein the downstream end of the coolant guide groove continues to the inner peripheral surface of the grindstone on the upstream side of the middle of the grindstone as viewed in the rotation direction of the grinding wheel. The coolant reservoir is being caused to extend continuously in the circumferential direction, according to claim 1 or 2 Symbol placement of the grinding wheel. The cooling liquid reservoir inclines downward and extends outward in the radial direction and inclines downward below the upper inclined surface substantially horizontally inward in the radial direction or downward inward in the radial direction. is defined between the projecting surface extending Te, grinding wheel according to any one of up to claim 1 or et 3.   The grinding wheel according to any one of claims 1 to 4, wherein a plurality of communication notches or communication holes communicating with the coolant reservoir from the upper surface thereof are formed in the base at intervals in the circumferential direction. .   The grinding wheel according to any one of claims 1 to 5, wherein the base has a lower inclined surface extending downwardly in the radial direction downwardly below the protruding surface.

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