JP3223269B2 - Solid material machining method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] The present invention is intended to produce hard and brittle materials such as silicon wafers, glass, ceramics and stones (hereinafter referred to as hard and brittle materials) as solid materials with high efficiency without cracking. They are going to be machined.

[0002]

2. Description of the Related Art When a hard and brittle material is cut or ground, a crack is generated on the surface to be processed by the processing force, and a large number of small cracks may be present on a finished surface of the material. A phenomenon occurs in which the crack propagates into the inside of the base material.

When a processed member is put to practical use with such cracks remaining, brittle fracture may occur starting from the crack, and in the case of hard brittle materials which are originally low in brittle fracture and are liable to cause brittle fracture, the products are processed by processing. The problem remains where the quality is to be reduced and the effectiveness of the material cannot be exploited.

For this reason, conventionally, in the case of this kind of material, machining is performed under a condition in which a large machining stress does not act so as not to cause a machining crack when cutting or grinding is performed, that is, in a minute machining unit. Was common.

[0005]

However, in such a conventional processing method, since the processing efficiency is limited to fine processing, low efficiency and high cost are unavoidable, and the spread of hard and brittle materials is inevitable. And the solution was required.

[0006] An object of the present invention is to propose a novel processing method capable of solving the conventional problems that have occurred in the machining of solid materials, particularly hard and brittle materials.

[0007]

SUMMARY OF THE INVENTION The present invention provides a method of machining a solid material using a pressure vessel body and a lid attached to the pressure vessel body to form a closed space therein. It is arranged in a closed space formed by the pressure vessel, and this closed space is held under a hydrostatic pressure environment that suppresses cracks generated in the material during processing, and in that state, a machine is mounted on the surface to be processed of the solid material. This is a method for machining a solid material, wherein the machining is performed.

In the present invention, a hard and brittle silicon wafer, glass, ceramics, stone, or the like is advantageously used as the solid material.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Cracks on a machined surface during machining are mainly caused by the application of tensile stress to the material between the tool and the tip during machining. At least the surface to be processed of the solid material to be processed is held in an environment under hydrostatic pressure, and machining is performed while maintaining that state. In this case, the tensile stress generated at the tip of the tool is the compressive stress of hydrostatic pressure And the generation of cracks during processing is suppressed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described more specifically with reference to the drawings. FIG. 1 schematically shows a machining apparatus suitable for carrying out the present invention. In the figure, reference numeral 1 denotes a pressure vessel main body, 2 denotes a closed space (pressure chamber) in which the pressure vessel main body 1 is fitted. A cover 3 for forming the P, a connecting bolt 3 for connecting the cover 2 to the pressure vessel main body, a turntable 4 for holding and rotating the solid material S, a fifth end 5 connected to the turntable 4 and a second end driving. The shaft connected to the motor M, 6 is a sealing mechanism disposed between the pressure vessel main body 1 and the lid 2, and 7 is processing means disposed in the closed space P. In this example, a linear groove is formed on the surface of the solid material S, and a processing tool (diamond needle) 7a, a holder 7b for holding the processing tool 7a, and both ends are fixedly held in a closed space P. Shaft 7c and this shuff Consisting slider 7e to adjust the pressing force of the original working tool 7a of the biasing force of the spring 7d to slide along 7c.

Reference numeral 8 denotes a passage connected to the sealed space P of the pressure vessel body 1, reference numeral 9 denotes a high-pressure pump for maintaining the sealed space P in a hydrostatic environment through the passage 8, and reference numeral 10 denotes a high-pressure pump 9. It is a pressure gauge.

In order to machine the solid material S (in this example, to form a linear groove with a diamond needle) using the apparatus having the above configuration, first, the solid material S is put on the turntable 4. The lid 2 is attached to the pressure vessel main body 1 to form a sealed space P therein. The pressing force is adjusted so that a groove having a predetermined depth is formed in the solid material S to press the processing tool 7a against the solid material S, and a low-viscosity liquid such as kerosene is supplied as a pressure medium into the closed space P. And maintain it in a hydrostatic environment.

Then, while maintaining this state, the motor M
Is driven to form a linear groove on the surface to be processed of the solid material S.

When machining is performed on the solid material S, a tensile stress acts on the material S during the processing, as shown in FIG. 2, and the tensile stress is used as a starting point to destroy the material and generate cracks on its surface. However, in the case of machining such as hard and brittle materials, the occurrence of such cracks is particularly noticeable.In the present invention, not only the materials but also the tools are subjected to the hydrostatic environment. The tensile stress generated in the material at the time of processing is canceled out by the compressive stress of hydrostatic pressure, so that the destruction of the material that progresses to a surface crack is avoided.
FIG. 3 shows a machining state when a material is machined by applying the present invention, and FIG. 4 shows an enlarged view of a main part of the machining tool (diamond needle) shown in FIG.

When the hard and brittle material is machined in the manner described above, cracking does not occur even in a large processing unit. The efficiency will be significantly improved.

For example, when a silicon wafer is machined with abrasive grains having a tool tip radius of about 20 μm, a machining amount of about 5 μm ^{2 in the} removal cross-sectional area or 400 MPa when machining with a machining amount of a machining depth of about 1 μm. 50
A pressure of about 0 MPa is required. Conversely, relatively low pressures are possible if not so high processing efficiency is required. The machining can be applied to grinding, lapping, and polishing in addition to cutting and cutting.

Furthermore, the hydrostatic pressure also depends on the processing form, and for example, the hydrostatic pressure applied differs between cutting and grinding. This is due to the difference in the working mechanism, but in any case, the working crack can be suppressed by applying the hydrostatic pressure during the working.

FIG. 5 shows the following procedure for forming a linear groove on the (111) plane of a silicon wafer having a thickness of 0.5 mm and a diameter of about 30 mm using the apparatus shown in FIG. The figure shows the results of investigations on the occurrence of cracks in the material with respect to changes in the groove cross-sectional area, performed under conditions.

Processing conditions Rotation speed of silicon wafer: 1.0 mm / s Hydrostatic pressure: 0,400 MPa Pressure medium: kerosene, turbine oil, air

In FIG. 5, the cracking rate is defined as a value obtained by integrating the lengths of cracks (Lareral) generated on both sides of the groove during processing and dividing the result by the length of the groove. By performing processing in a hydrostatic environment according to the following, the occurrence of cracks is reduced, the maximum groove cross-sectional area without cracks tends to be large, and under hydrostatic pressure of 400 MPa, processing without applying hydrostatic pressure It is apparent that even if the processing is performed at an efficiency of about 10 times as compared, the processing can be performed without generating a crack.

FIGS. 6 (a) and 6 (b) show the results of observing the plane of the groove when kerosene was used as the pressure medium and the hydrostatic pressure was changed to 0 MPa and 400 MPa, and the groove width was variously changed. is there. Groove width (groove depth 0.12μ)
m, 0.16 μm) are relatively small, but as is clear from FIG. 6, when processed under hydrostatic pressure, there is little crack at almost the same groove width. Understand.

FIG. 7 and FIG. 8 each show a case in which a silicon glass having a thickness of about 1 mm and a diameter of about 30 mm is used, and processing is performed under the following conditions to form a linear groove on the surface thereof. It shows the result of an investigation on the occurrence of cracks in the material with respect to changes.

Processing conditions of FIG. 7 Rotation speed: 0.815 mm / s Hydrostatic pressure: 0,400 MPa Pressure medium: Kerosene

Processing conditions in FIG. 8 Rotation speed: 6.59 mm / s Hydrostatic pressure: 0,400 MPa Pressure medium: Kerosene

The data shown in FIG. 6 above relates to a silicon wafer. Such a material has a crystal structure having a diamond structure, whereas glass has an amorphous structure having no crystal. Despite the difference in structure, even when a groove is formed in glass, the critical groove cross-sectional area is increased by applying hydrostatic pressure as shown in FIGS. 7 and 8, and in machining under hydrostatic pressure environment, It is clear that the effect of suppressing cracks on the material surface is apparent, and it was confirmed that the present invention can be applied to any hard and brittle material.

[0026]

According to the present invention, it is possible to process a solid material with high efficiency even if it is a hard and brittle material that is liable to crack during machining.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a machining apparatus suitable for carrying out the present invention.

FIG. 2 is a diagram showing a state of a material and a machining tool in machining.

FIG. 3 is a diagram showing a state of a material and a processing tool when the present invention is implemented.

FIG. 4 is an enlarged view of a main part of the processing tool.

FIG. 5 is a diagram showing a result of investigation of cracks in the example.

FIGS. 6A and 6B are enlarged views of a groove when processing is performed in an example.

FIG. 7 is a diagram showing a result of investigation of a crack in an example.

FIG. 8 is a diagram showing a result of investigation of cracks in the example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pressure vessel main body 2 Lid 3 Connecting bolt 4 Turntable 5 Shaft 6 Seal mechanism 7 Processing means 7a Processing tool 7b Holder 7c Shaft 7d Spring 7e Slider 8 Passage 9 High pressure pump 10 Pressure gauge s Solid material P Sealed space M Motor

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-10-6143 (JP, A) JP-A-9-187815 (JP, A) JP-A 62-153039 (JP, U) (58) Survey Field (Int. Cl. ⁷ , DB name) B23B 1/00 B24B 1/00 B24B 19/22 B28D 1/00 JICST file (JOIS)

Claims (2)

(57) [Claims] When a solid material is machined using a pressure vessel main body and a lid attached to the pressure vessel main body to form a closed space therein, the solid material is applied to the pressure vessel main body and the lid. Placed in an enclosed space formed by machining, maintaining this enclosed space in a hydrostatic environment that suppresses cracks in the material during processing, and subjecting the surface of the solid material to machining in that state A method of machining a solid material. 2. The method for machining a solid material according to claim 1, wherein the solid material is a hard and highly brittle material.