JPS5845852A - Index table type wafer grinder - Google Patents

Abstract

PURPOSE:To make it possible to automatically perform a work processes from the mounting of a wafer to its super-finishing work by providing in parallel a super-finishing mechanisn for pressing down a super-finish whetstone, while horizontally rocking it, on a grinding board designated on the title equipped with rough grinding and finish grinding mechanisms. CONSTITUTION:An index table 1 is intermittently indexed with rotation, and a wafer 8 is worked in order, from rough work to finish, allowing it to be indexed into a super-finish station. A super-finishing mechanism is constituted such that a super-finish whetstone 28 is moved downward while rocking via an accentric pin 31 with a main shaft 25 driven by a driving motor, and the abrasive grain layer 30 of the whetstone 28 makes contact with the wafer 8 already subjected to finish work with a constant pressure. Thus, in super-finishing work process, micro-work is carried out by pressing down the wafer 8 under a constant pressure, so that it is possible to automatically perform micro-finishing work without any accurate positioning.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wafer grinder for polishing the surface of a silicon wafer, and more particularly to an index table type wafer grinder for automatically attaching, grinding, and removing a wafer.

In a conventional index table type wafer grinder, a method is implemented in which a diamond grindstone is rotated and moved horizontally toward the wafer to grind the wafer.

In this method, the finished surface roughness of the wafer is determined by the grain size of the grindstone, as shown in FIG. The vertical axis in FIG. 1 indicates the surface roughness (μm), the horizontal axis indicates the particle size number of the diamond grinding wheel, and the value within 0 indicates the maximum particle size (μm). Also, the maximum amount of abrasive grains that can be cut in one grinding process is less than the size of the abrasive grains. Therefore, in order to efficiently grind wafers, rough grinding is performed with a coarse-grained whetstone, and rough grinding is performed with a medium-grained whetstone. It is necessary to perform medium grinding using a grinding wheel, and finish grinding using a fine grindstone. The following method can be considered for this purpose.

(1) Machining is performed using one machine with one grindstone axis.

(b) Replace the grindstone manually.

(b) Automatically replace the grindstone.

(If) Processing is performed using three machines with one grindstone axis.

(c) Each machine is dedicated to roughing, medium, and finishing, and processed products are transferred between these machines.

(III) Processing is performed using one machine with three grindstone axes.

) The three axes are used for roughing, medium and finishing, and the table with the workpiece attached is moved (rotated).

Regarding (a) above...it is inefficient.

Regarding the above (b)...This is a so-called grinding machine with a tool changer. Currently, when a tool is attached to a spindle, runout occurs due to the small gap between the two, making it difficult to maintain accuracy within the required several micrometers.

Regarding the above (/→)...Production costs are high and processed products are easily damaged during transportation.

(above) is efficient and economical. Therefore, at present, the above method (by ship) is common.

Next, when +aooo is selected as a finishing whetstone for semi-mirror grinding that requires a surface roughness of 0°02μm@degree, the first
As shown in the figure (the maximum size of the abrasive grains is 5 μm and the depth of cut is 1
．． The depth of cut is 7 μm, but taking into account the variation in abrasive grains, the maximum depth of cut is 1 μm.

However, the finish grinding wheel is 1μ compared to the medium grinding wheel.
It is actually difficult to set the height difference to m.

As a possible method for the above, it is possible to measure the machined surface and make corrections by adding foot marks to the respective cutting axes, but this would be very expensive.

Therefore, for processes that require a level difference of 0.5 μm or less, such as semi-mirror grinding, which requires a surface roughness of about 0.02 μm, it is almost impossible to grind by rotating the grinding wheel and moving it horizontally. That would be close to impossible.

An object of the present invention is to provide a wafer grinding machine that enables top processing in the horizontal direction while rotating the above-mentioned grindstone.

In order to achieve the above object, the present invention is provided with an index table that rotates in a predetermined manner and stops for a certain period of time, and around this index table there are rough grinding and finish grinding mechanisms,
In an index table type wafer grinding machine that is equipped with a rope ink mechanism and an unloading mechanism, and performs rough grinding, finish grinding, and removes and carries out the wafer from the index table when the index table is stopped, and carries the wafer onto the index table. This machine is equipped with a super-finishing mechanism for super-finishing Ueno by pressing the super-finishing whetstone with a constant pressure while swinging it in the horizontal direction. Embodiments of the present invention will be described below with reference to FIGS. 2 to 5, which show embodiments of the present invention.

FIG. 2 is a plan view showing the entire wafer grinding machine for carrying out the present invention, FIG. 3 is a partially sectional front view taken from arrow A in FIG. 2, FIG. 4 is a side view showing the super-finishing mechanism, and FIG. The figure is a cross-sectional front view showing the drive section of the super-finishing mechanism.

In Fig. 2, reference numeral 1 designates an index table, which is rotatably placed on the pet 2, rotates in the direction of the arrow every 72 degrees by a drive mechanism (not shown) installed in the pet 2, and stops for a certain period of time. I'm doing it like I'm doing it.

Also, 42 diagrams are shown on the index table 1 above.■■■■
Five vacuum suction mechanisms (3) are installed in (1), and around them are a loading mechanism (1), a grinding mechanism (1), a super-finishing mechanism (3), and an unloading mechanism (2).

The vacuum suction mechanism 3 vacuum suctions the wafer 8 onto the mounting surface 3a when vacuum air is supplied, and lifts the wafer 8 above the mounting surface 3a when pressurized fluid is supplied. Although the o-ding mechanism is only shown as a block, it conveys the processed raw material wafer 8 and
It is placed on the mounting surface 3a of the vacuum suction mechanism 3 that has reached the position. The grinding mechanism 5 has a pet 9 and this pet 9.
A flamm 10 moves forward and backward toward the index table 1 on its top, a common stand 11 is slidably supported on the vertical sliding surface of the Konokomura 10, and a column is mounted on the front of the common stand 11. A grinding wheel 12a and a finish grinding wheel 12b, a grip 13 that moves only one of the rough grinding wheels 12a in the vertical direction, and a rough grinding wheel 12a and a finish grinding wheel fixed at a rear position of the common table 11. 12b
A motor 16 is provided for fixing a boot IJ 14C connected via a belt 15 to pulleys 14a and 114b mounted on the same axis.

Although a drive mechanism for moving the column 10 forward and backward and a drive mechanism for moving the common stand 11 up and down are not shown, both are installed in the pet 9. The super finishing mechanism supports the above index table 1 with a pet 2.
A cylinder 18 is fixed to the lower surface of the tip of the bracket 17, and a piston rod 19 is fixed to the tip of the piston rod 19 that slides vertically inside the cylinder 18. The support 20 and the sabot 20 are slidably inserted in parallel to each other at both ends, and the lower end is inserted into the bracket 17 and the upper end is inserted into the end piece 22.
two guide rods 21 fixed to the guide rods 21; a spindle head 24 fixed to the tip of an arm 23 fixed to the guide rods 21 in parallel with the piston rod 19 and rotatably supporting the main shaft 25; It is formed of a drive motor 26 fixed to the upper surface of the head 24 and connected to the main shaft 25, and a reduction gear box 27, and the super-finishing whetstone fixed to the lower end of the main shaft 25 is rotated by the drive motor 26, and the cylinder 18, it is moved up and down via a piston rod 19, a support 20, and an arm 23.

The super-finishing whetstone has a disc-shaped whetstone main body 29 with a mountain-shaped cross section, an abrasive grain layer 30 fixed to the lower surface of the whetstone main body 29, and a central boss portion 9a of the whetstone main body 29. Insert the spherical large diameter part 31a so that it can freely slide in the vertical direction, and
It is prevented from being inserted outside by the ring 32, and the detail 31
Insert the tip of the set screw 33 so as to press it against the upper end of the hole 25a formed at an eccentric position on the lower end surface of the main shaft 25.
A spring 34 is inserted between the eccentric pin 31 which is prevented from being inserted to the outside, the spindle head 24 and the grindstone body 29, and always presses the grindstone body 29 downward, and a recess 29b of the grindstone body 29. and a plurality of water supply holes 36 that simultaneously penetrate the abrasive grain layer 30 in the vertical direction and supply water from an upper water supply nozzle 35 to the surface of the abrasive grain layer 30 to discharge chips.The main shaft 25 rotates. When this happens, the grinding wheel main body 29 and the abrasive grain layer 30 swing through the eccentric pin 31. ◎The unloading mechanism 〇 is shown only as a block like the loading mechanism A, but the wafer after grinding When it reaches position ■ and stops,
The wafer 8 is removed from the mounting surface 3a of the vacuum suction mechanism 3 and carried out to a predetermined position. With the above configuration, the index table 1 is
When it rotates and stops, the loading mechanism filter loads the processed rough material wafer 8 onto the mounting surface 3a of the vacuum suction mechanism 3 at position ■, and vacuum air is supplied to the vacuum suction mechanism 3 to remove the wafer. 8 onto the mounting surface 3a. In addition, in the grinding mechanism, the rough grinding wheel 12a is adjusted in advance to an upper position than the finish grinding wheel 12b by an amount corresponding to the finishing allowance, and the motor 1
6 provides a rough grinding wheel 12a and a finish grinding wheel 12.
Move forward while turning b at the same time, and perform rough grinding and finish grinding on the squares 8 at positions ■ and ■. On the other hand, when the super-finishing mechanism rotates the main shaft 25 by the drive motor 26, the super-finishing abrasive stone field is oscillated through the eccentric bin 31 and moved downward by the piston rod 19, so that the abrasive grain layer 30 is at the position (2) after completion of finish grinding. When it comes into contact with a certain wafer 8, only the downward movement of the super-finishing grindstone section is stopped, and the wafer 8 is subjected to super-finishing by the pressing force of the spring 35.

When the super-finishing process is completed after a predetermined period of time has elapsed, the super-finishing whetstone moves up in a rotating state, and stops rotating when it returns to this position. Further, the unloading mechanism 2 removes the wafer 8 at position (3) after superfinishing from the mounting surface 3a and carries it out to a predetermined position.

When the rough grinding, finish grinding, super finishing, loading, and unloading operations are completed in this way, the index table 1 rotates 72 degrees and stops, and the above operations are repeated thereafter.

Next, Fig. 6 shows another super-finishing whetstone part of the super-finishing mechanism,
In this figure, an eccentric pin 37 is fastened to the lower surface of the large diameter of the lower end of the main shaft 25. It is formed from an eccentric bin 37b fixed at a more eccentric position, and a spring 40 inserted into a hole 37c penetrating vertically through the center of the eccentric bin 37b and pressing the super finishing grindstone part downward via a slide piece 38. , the O-ring 41 is inserted into the outer circumferential surface of the super-finishing whetstone section, and the outer circumferential surface 11 of this O-ring 39! !
is pressed against the inner peripheral surface of the lower end of the outer ring 40 fixed to the outer peripheral surface of the lower end of the spindle head 24.

In the case of this configuration, as the main shaft 25 rotates, the super-finishing whetstone part revolves while swinging through the eccentric bin 37, and at the same time, the inner circumferential surface of the stationary outer ring 40 is super-finished through the O-ring 41. Since the finishing whetstone section rotates, uneven wear of the abrasive grain layer of the super finishing whetstone section can be reduced.

As mentioned above, the super-finishing mechanism of the present invention presses the wafer with a constant pressure while rocking the super-finishing grindstone to perform micro-machining, so the configuration is simple and easy without particularly precise positioning. Can be processed to a super finish.

Therefore, the super-finishing mechanism according to the present invention can be implemented in a wafer grinding machine that automatically performs wafer mounting, rough grinding, finish grinding, and wafer mounting, thereby improving wafer processing accuracy. 0 that has the effect of

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the relationship between the abrasive grain layer and surface roughness of the diamond grinding wheel when Ueno S is ground by moving the diamond grinding wheel in the horizontal direction while rotating, and Fig. 2 shows the entire implementation apparatus of the present invention. 3 is a partially sectional front view taken in the direction of arrow A in FIG. 2; FIG. 4 is a side view showing the super-finishing mechanism; FIG. FIG. 6 is a sectional front view showing the drive section of another superfinishing mechanism of the present invention.

Claims (2)

[Claims] (1) An index table that rotates at a predetermined angle and stops for a certain period of time is provided, and a rough grinding/finish grinding machine 111, a rotink mechanism, and an unrope ink mechanism are provided around this index table, and when the index table stops, Rough grinding, finishing grinding, and index table type wafer grinding machines that remove and carry out wafers from the index table or carry wafers onto the index table.The super finishing grindstone is pressed with a constant pressure without making a horizontal rocking motion. An index table type wafer grinding machine characterized by being equipped with a super-finishing mechanism for super-finishing wafers. (2) The index table-shaped wafer according to claim 1, which comprises a super-finishing mechanism that super-finishes the wafer by rotating the super-finishing grindstone while horizontally oscillating (revolving) it and pressing it with a constant pressure. Grinder