JPH05285826A - Grinding and polishing method - Google Patents

Abstract

PURPOSE:To provide a grinding and polishing wheel and a method capable of carrying out polishing work continuously after grinding work efficiently and in high processing precision. CONSTITUTION:After grinding is finished, by retreating a grinding wheel 1 or a workpiece S so that a gap is made between a grinding wheel grinding surface and a workpiece surface and supplying a mechanochemical abrasive A to the workpiece S while giving relative motion between the grinding wheel 1 and the workpiece S, the workpiece S is polished. The workpiece S is polished by mechanochemical work. Additionally, the abrasive A removes ground dust attached to the grinding surface of the grinding wheel 1 at the time when the abrasive A flows out to the outer peripheral side of the grinding wheel 1 through the gap between the grinding surface of the grinding wheel 1 and the workpiece S.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grinding / polishing method.

[0002]

2. Description of the Related Art A polishing process is sometimes performed after the grinding process in order to further smooth the surface of a workpiece. Mechanochemical polishing is known as one of the polishing processes. Mechanochemical polishing polishes a workpiece using an abrasive having a mechanochemical effect. Mechanochemical abrasives are softer than the work piece and consist of abrasive particles that undergo a solid phase reaction with the work piece. In the mechanochemical polishing, a chemical reaction is induced by mechanical energy applied at a contact point between an abrasive grain and a workpiece, and surface polishing with a small processing unit is performed. According to the mechanochemical polishing, it is possible to obtain a high-precision and high-quality machined surface with almost no process-altered layer.

[0003]

Conventionally, when polishing is performed after surface grinding, a workpiece ground by a grinding machine is transferred to a grinding machine and the ground surface is ground. Therefore, it takes a lot of time to attach and detach the work piece. Further, if the work piece is not properly attached to the polishing device, the machining accuracy such as flatness is greatly reduced.

The present invention provides a grinding / grinding machine capable of performing a grinding work following a grinding work efficiently and with high processing accuracy.
It is intended to provide a polishing method.

[0005]

In the grinding / polishing method of the present invention, after finishing the grinding, the grindstone or the work is retracted so that a gap is formed between the grindstone grinding surface and the surface of the work, and the grindstone is ground. And a workpiece are subjected to relative motion to supply a mechanochemical abrasive to the workpiece to polish the workpiece.

The size of the gap between the grinding surface of the grindstone and the surface of the workpiece during polishing is suitable to be about the particle size of the abrasive grains of the mechanochemical abrasive.

The relative movement of the grindstone and the workpiece may be either rotary movement or linear movement. You may make it give a motion similar to the time of the last grinding to a grindstone. in this case,
It is efficient because the polishing operation can be performed simply by retracting the grindstone or the work piece and supplying the mechanochemical polishing agent.

As the mechanochemical polishing agent, the following polishing agents are used depending on the material of the workpiece. When the workpiece is silicon, a polishing agent in which fine silica powder or BaCO ₃ powder is suspended in an alkaline solution such as KOH aqueous solution, and in the case of sapphire, a polishing agent in which SiO ₂ powder is suspended in water or an alkaline solution, In the case of silicon nitride or silicon carbide, an abrasive obtained by suspending Cr ₂ O ₃ powder or Fe ₂ O ₃ powder in water is used.

[0009]

[Function] Grinding the workpiece by retracting the grindstone or the workpiece slightly (about the abrasive grain size of the abrasive) and supplying mechanochemical abrasive to the workpiece while giving relative motion between the grindstone and the workpiece To do. The workpiece is polished by mechanochemical action. It is possible to perform the work in a state where the workpiece is fixed to the same work table through the grinding process and the polishing process without removing the work item from the work table when shifting from the grinding process to the polishing process.

Further, the abrasive grains of the abrasive remove the grinding dust attached to the grinding surface of the grindstone during the polishing operation.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of an apparatus for carrying out the method of the present invention, showing a state in which a workpiece (silicon wafer) is being polished.

A grinding wheel 1 is fixed to the lower end of a vertically mounted wheel mounting shaft 4. An annular abrasive grain layer 3 is formed on an annular portion 2 provided at the lower end of the grinding wheel 1 so that the grinding surface is horizontal. The abrasive grains of the abrasive grain layer 3 are diamond abrasive grains, and the bond material is vitrified bond. The average grain size of the diamond abrasive grains is 5 μm, and the volume ratio is 30%. A steel polishing plate 5 is fixed to the inner bottom surface of the grinding wheel 1. The surface of the polishing plate 5 is highly accurately flattened, and a plurality of radially extending guide grooves 6 are provided. The size of the gap between the grinding surface of the abrasive grain layer 3 and the surface of the polishing plate 5 should be 1 to 100 μm.
By setting it to be about m
To work efficiently. An abrasive supply hole 7 is provided so as to penetrate through the wheel mounting shaft 4, the grinding wheel 1, and the center of the polishing plate 5, respectively. A pump (not shown) for supplying the mechanochemical abrasive is connected to the abrasive supply hole 7 via a rotary joint. The guide groove 6 guides the abrasive A supplied to the central portion of the polishing plate 5 to the outer peripheral portion of the polishing plate 5.

A method of polishing a silicon wafer, which has been ground, in the apparatus configured as described above will be described.

The silicon wafer S is held by the vacuum chuck 9 on the work table 8. When the grinding process is completed, the grinding wheel 1 is raised by 2 μm. Abrasive A while rotating the grinding wheel 1 and the work table 8
Is supplied to polish. Abrasive A is BaCO ₃ fine powder K
It is suspended in an aqueous OH solution. The average particle size of the fine silicon powder is 10 μm. The silicon wafer S is polished by the mechanochemical action. Further, when the polishing agent A flows between the ground surface of the abrasive grain layer 3 and the silicon wafer S and flows out to the outer peripheral side of the abrasive grain layer 3, it removes grinding debris attached to the ground surface of the abrasive grain layer 3. To do.

When the grinding and polishing were carried out by the above method, the silicon wafer was mirror-finished. The work time, including setup change, was also greatly reduced to less than 70% of the conventional method.

In the above embodiment, the abrasive was supplied from the central portion of the grinding wheel, but the abrasive may be supplied from a plurality of locations on the inner peripheral portion of the grinding wheel. In this case, it is desirable to use a grindstone with a comb-like groove. Also,
Although the guide groove of the polishing plate is radial, it may be provided in a spiral shape.

[0017]

According to the present invention, the work is not removed from the work table when the grinding process is changed to the polishing process, and the work is fixed in the same work table through the grinding process and the polishing process. It can be carried out. Therefore, the polishing work following the grinding work can be performed efficiently and with high processing accuracy.

Further, the abrasive grains of the abrasive remove the grinding dust attached to the grinding surface of the grindstone during the polishing operation. Therefore, even if the dressing is not frequently performed, the grinding operation can be stably continued for a long time.

[Brief description of drawings]

1 is an example of an apparatus for carrying out the method of the invention,
The state where the workpiece is being polished is shown.

[Explanation of symbols]

 1 Grinding Wheel 2 Annular Part 3 Abrasive Grain Layer 4 Wheel Mounting Shaft 5 Polishing Plate 6 Guide Groove 7 Abrasive Supply Groove 8 Work Table 9 Vacuum Chuck A Abrasive S S Workpiece (silicon wafer)

Claims (1)

[Claims] 1. Grinding for grinding a workpiece and then polishing
In the polishing method, after finishing the grinding, the grindstone or the work piece is retracted so that a gap is created between the grindstone grinding surface and the work surface, and the mechanochemical is performed while giving relative motion between the grindstone and the work piece. A grinding / polishing method, which comprises polishing a workpiece by supplying an abrasive to the workpiece.