JPS634938B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a vacuum suction and fixing device, and more particularly to a chuck table that suctions and fixes a thin substrate such as a semiconductor wafer in a process of cutting the same.

(2) Background of the technology In the manufacturing process of semiconductor devices, wafer processing such as exposure, heat treatment, vapor deposition, and chemical vapor deposition (CVD) is
Processed wafers with a thickness of, for example, 625 μm are cut to a thickness of, for example, 490 μm before final assembly. is done on the opposite back side.

A vacuum suction fixing device for cutting a wafer will be explained with reference to the schematic cross-sectional view of FIG. The device 10 is placed on a chuck table 11 made of a porous material, and the device 10 is mounted on a rotating turntable 1. Cup wheel (grindstone) for cutting
6 is placed above the turntable 1 and rotates at high speed in the direction shown by the arrow. In the figure, 3 is a motor, 2 is a spindle, 4 is a driving means for moving the spindle 2 up and down, and 5 is a stand. A mechanism for transmitting the rotation of the motor 3 to the cup wheel 6 is built into the spindle 2 . Note that the dashed-dotted line in the same figure indicates the center line of the turntable 1.

The turntable 1 has a configuration as shown in the schematic plan view of FIG. 2, on which a plurality of vacuum suction fixing devices 10 are mounted,
and cup wheel 6 rotate in the directions shown by the arrows. Note that in FIG. 2 and subsequent figures, the same parts as those already shown are designated by the same reference numerals.

The vacuum suction fixing device 10 has the configuration shown in the cross-sectional view of FIG.
A porous chuck table is disposed on the upper table 18, and the wafer 12 is evacuated from the exhaust duct 15 in the direction shown by the arrow in the figure to evacuate the vacuum chamber 19. 11 by suction and fixation. In order to maintain the vacuum, a plastic cover 13 is applied to the outer periphery of the chuck table 11.
A sealing plastic 14 is impregnated along the outer edge of 1.

(3) Prior Art and Problems Wafer cutting in the prior art will be explained with reference to the cross-sectional view in FIG. The tip 7 of the cup wheel 6 cuts the wafer by about 200 μm, for example. At this time, a portion of the wafer 12 indicated by 12' is crushed, and the surface 12 is formed flat to a degree close to a mirror finish. The portion indicated by 8 in the figure is a cup that holds the tooth tips 7, and the cup wheel 6 is connected to the spindle 2 via a shaft 9. The dash-dotted line indicates the center line of the cup wheel. Returning to FIG. 1, when a force V acts in the direction of the arrow due to evacuation, V is decomposed into a lateral (horizontal) force F2 and an upward force F1.
In experiments using the illustrated apparatus, it has been confirmed that F2>>F1, and since such a force relationship holds, it is possible to cut a wafer as shown in FIG. 4.

When the above-mentioned cup wheel is used for a long period of time (wafer cutting), the polishing liquid used during cutting may seep into the chuck table 11, and the wafer 12 and chuck table 11 may be damaged.
The outer edge of the chuck table 11 may be worn or fall off due to contact with the outer edge of the chuck table 11, which may cause the outer periphery of the chuck table 11 to deform and crack or chip the wafer. Even though the parts were impregnated with plastic, there was a vacuum leak (vacuum leak), and there were cases where the wafer suction was not sufficient. Among these failures, if the wafer is cracked or chipped, the loss is significant because the wafer process has already been completed for the wafer.

(4) Purpose of the Invention In view of the above-mentioned conventional problems, the present invention provides a vacuum equipped with a chuck table that has sufficient suction power to wafers, does not damage the wafers, and does not wear or break itself. To provide a suction fixing device.

(5) Structure of the Invention According to the present invention, a chuck table is provided whose periphery is closely surrounded by an outer periphery of a high-strength metal or ceramic material that does not allow air to pass through, and this outer periphery is made of a chuck table. This is accomplished by providing a vacuum suction means configured to engage the pick table and the upper table of the device.

(6) Examples of the invention Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 5 shows a cross section of the vacuum suction fixing device according to the present invention. This device 30 is similar to the conventional device shown in FIG. 3 except for the chuck table 21, so The same parts as those shown are indicated by the same reference numerals, and the configuration and function of each part is completely the same as that of the conventional device, so a detailed explanation thereof will be omitted.

In the illustrated embodiment, the periphery of the chuck table 21, which is formed of a porous material (e.g. ceramic), is surrounded by an outer periphery 20 made of a strong, sufficiently dense and airtight metal. Outer periphery 2
0 is formed so as to be very closely adjacent to the chuck table 21. The material for the outer circumferential portion 20 may be any material that satisfies the above conditions, and it is also possible to use ceramics that do not allow air to pass through. As can be understood from the figure, in order to ensure close contact between the chuck table 21 and the outer peripheral part 20, the lower part of the outer peripheral part 20 engages with the upper table 18, and the central part thereof forms a step inward. This stepped portion is configured to engage with the lower portion of the chuck table 21. Further, the dimensions of the outer periphery of the wafer to be placed on the chuck table 21 are set in advance so that the outer periphery of the wafer rests on approximately the center of the upper surface of the outer periphery 20.

By providing the outer peripheral portion 20 as described above, the chuck table 21 is attracted by the vacuum chamber 19 when exhausting from the exhaust duct 15, and since the chuck table 21 is porous, the wafer 1
2 is attracted and fixed toward the chuck table 21. The above-described configuration of the wafer 12, chuck table 21, and outer circumferential portion 20 reduces the possibility of polishing liquid seeping into the chuck table, and the outer edge of the wafer rests on the hard surface of the outer circumferential portion 20.
The chuck table rarely wears or falls off, the wafer is always placed flat on the flat chuck table 21, and the suction force acts uniformly on the entire wafer, so there is no significant risk of cracking or chipping of the wafer. decreased.

In addition, since the structure of the outer peripheral portion consists of only two steps and the material is metal or ceramic, there are no particularly difficult problems in manufacturing compared to the case of the prior art.

(7) Effects of the Invention As explained above in detail, in the vacuum suction fixing device according to the present invention, the chuck table is surrounded by an outer peripheral part made of metal or ceramic that is in close contact with the chuck table. In addition to preventing wear of the chuck table, the chuck table is always kept flat and perfect, thereby avoiding damage such as cracking of the wafer, which is highly effective in improving the manufacturing yield of semiconductor devices. Note that although the above description has been made by taking wafer cutting as an example, the scope of application of the present invention is not limited thereto, and extends to apparatuses used for processing substrates other than wafers.

[Brief explanation of the drawing]

Figure 1 is a schematic cross-sectional view of the wafer cutting device, Figure 2
The figure is a plan view of a turntable used with the device shown in Figure 1, Figure 3 is a schematic sectional view of a conventional vacuum suction fixing device, Figure 4 is a schematic sectional view showing cutting of a wafer, and Figure 5 is a schematic sectional view of the present invention. It is a sectional view of the vacuum adsorption fixing means concerning this. DESCRIPTION OF SYMBOLS 1... Turntable, 2... Spindle, 3... Motor, 4... Driving means, 5... Stand, 6... Cup wheel, 7... Tooth tip, 8... Cup, 9... Shaft, 10, 30
... Vacuum suction fixing device, 11, 21... Chack table, 12... Wafer, 13... Plastic cover, 14... Sealing plastic, 15... Exhaust duct, 16... Lower table, 17... Fixing means, 18
...Upper table, 19...Vacuum chamber, 20...Outer periphery.

Claims (1)

[Claims] 1 A vacuum chamber provided on the upper table is evacuated by an upper table and a lower table fixed together, and a vacuum suction system is used to suction and fix the substrate to be processed onto a porous chuck table provided on the upper table. In the fixing means, the chuck table is surrounded by an outer periphery, the outer periphery is made of a material that is difficult to pass through air, a lower portion of the outer periphery is in meshing engagement with the upper table, and a central portion of the outer periphery is A vacuum suction fixing device characterized in that the portion has a step formed inwardly, and the step portion is configured to mesh with and engage with a lower portion of the chuck table.