JPH0577148A - Retract mechanism for grinding machine - Google Patents

Abstract

PURPOSE:To provide retract mechanism enabling recovery or the continuation of work without residual damage even in the case of power supply being stopped during the grinding of a semiconductor wafer demanded to be highlly accurate in its machined surface, diameter-enlarged and extremely thin regarding an automatic surface grinding machine for grinding the semiconductor wafer. CONSTITUTION:An elevating device has a motor 7 as drive source, and a spindle 6 is rotated by another motor 7 as drive source. A condenser is interposed in a power circuit between each motor 7 and each power supply. The condenser switches the polarity of the motor 7 by accumulated electric power at the power failure time so as to rotate the motor 7 reversely. Accordingly, even if power failure is generated during the grinding of a semiconductor wafer, the polarity of the motor 7 is switched to rotate the motor 7 reversely by electric power accumulated in the condenser, so that the semiconductor wafer is prevented from being damaged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic surface grinder for grinding a semiconductor wafer, and more specifically, it grinds a semiconductor wafer which requires a highly accurate surface finish, a large diameter and an extremely thin surface. The present invention relates to a retract mechanism capable of recovering damage without remaining even when power supply is stopped.

[0002]

2. Description of the Related Art Semiconductor wafers of this type are required to have a highly accurate finished surface as well as to be extremely thin and have a large diameter due to the yield of products. An automatic surface grinder that grinds wafers is also required to have a mechanism capable of achieving high precision, ultra-thinning, and diameter expansion of the finished surface, which is an urgent task.

Conventionally, an automatic surface grinder for grinding a semiconductor wafer grinds a set cutting allowance by lowering a grinding wheel, but if power supply is stopped for some reason during grinding, In other words, when a power failure occurs, the grinding wheel stops in a state of pressing the upper surface of the semiconductor wafer, and almost no damage remains in the conventional semiconductor wafer having a small diameter and a thickness. Thinning,
The brittle semiconductor wafer whose diameter has been enlarged has damages such as cracks, cracks, and scratches due to the pressure, and an expensive semiconductor wafer on which a circuit has already been printed cannot be used.

[Object of the Invention]

In view of the above-mentioned reasons, the present invention has been made as a result of intensive studies to solve the above-mentioned problems, and as a result, it is possible to sufficiently deal with high quality, ultra-thinning and diameter expansion of semiconductor wafers.
The purpose of the present invention is to provide a mechanism for recovering a semiconductor wafer that is being ground without damage even during a power failure.

[Constitution of the invention]

The structure of the present invention comprises a chuck mechanism, a semiconductor wafer, a cup wheel type grinding wheel, and a spindle shaft movably supported on a base body through an elevating means, and the axis of rotation of the chuck mechanism is provided. In the automatic surface grinding machine in which the spindle and the rotation axis of the spindle shaft are substantially parallel to each other, and the grinding surface of the cup wheel type grinding wheel passes through the center point of the semiconductor wafer at a constant interval, A motor is used as a drive source to lower a cup wheel type grinding wheel to grind a semiconductor wafer, and the spindle shaft is rotated using the motor as a drive source, and a condenser is provided in the power supply circuit between each motor and each power supply. The configuration is such that each motor is reversely rotated in the event of a power failure.

Examples of the invention

A retracting mechanism for a semiconductor wafer according to the present invention, which has achieved the above object, will be described with reference to the drawings of an embodiment.

FIG. 1 is a schematic plan view for explaining an automatic surface grinder using a rotary table according to an embodiment of the present invention, FIG. 2 is a schematic side view for explaining the present invention, and FIG. 3 is a condenser. FIG. 3 is a schematic view of a motor provided with

The present invention relates to an automatic surface grinder that grinds a semiconductor wafer W. More specifically, during grinding of a semiconductor wafer W which requires a highly accurate finished surface, a large diameter, and an extremely thin surface. If the power supply to the
The present invention relates to a mechanism capable of recovering a semiconductor wafer W during grinding without causing any damage to the semiconductor wafer W during the grinding process. The chuck mechanism 2 is fitted to the table 1 and rotates by itself, and the chuck mechanism 2 is vacuum-adsorbed. Semiconductor wafer W, a cup wheel type grinding wheel 3 disposed above for grinding the upper surface of the semiconductor wafer W, and a lifting means 4 for fixing the cup wheel type grinding wheel 3 to the lower end.
And a spindle shaft 6 which is supported by a base body 5 so as to be able to move up and down and rotates by itself, and a rotation axis a of the chuck mechanism 2 and a rotation axis b of the spindle shaft 6 are substantially parallel to each other. In the automatic surface grinder in which the grinding surface of the cup wheel type grinding wheel 3 is arranged with a constant interval passing at least the center point of the semiconductor wafer W, the elevating means 4 is used.
Uses a motor 7 as a drive source to lower the cup wheel type grinding wheel 3 at a constant fine speed to grind a set amount of cutting allowance on the upper surface of the semiconductor wafer W, and the spindle shaft 6 rotates using the motor 7 as a drive source. Therefore, a power storage circuit 9 between each of the motors 7 and each of the power supplies 8 is provided with a capacitor 9a for storing electricity, and the polarity of the motor 7 is switched by the electricity stored in the capacitor 9a during a power failure. To rotate in reverse.

Usually, the operating state of the semiconductor wafer W, which is the object to be ground of this type of automatic surface grinder, will be specifically described. First, as shown in FIG.
The semiconductor wafer W is transferred to the delivery side transfer belt 12 by the delivery side transfer belt 12 provided immediately below the delivery side cassette 11 which is stored and stored in a ladder type partition frame and is movable up and down and the front surface is open. 12 is placed on the guide,
The semiconductor wafer W on the delivery-side transfer belt 12 is adsorbed to the suction pad 14 provided at the tip of the delivery-side inversion arm 13 located below and reversible, and the delivery-side inversion arm 13 is inverted to preposition. Placed on 15,
Next, the semiconductor wafer W is vacuum-sucked to the lower surface of the suction pad 17 provided at the tip of the wafer transfer arm 16 which is vertically movable and has a horizontally rotating mechanism, and is transferred onto the rotary table 1 of the grinder. It is a thing.

The rotary table 1 is provided with a plurality of chuck mechanisms 2 each of which is self-rotating and which attracts a circular vacuum, and the rotary table 1 automatically and intermittently repeats rotation and stop at a stop position. Then, the spindle shaft 6 to which the cup wheel type grinding wheel 3 is fixed descends from the upper side of each chuck mechanism 2 to the tip thereof, and the upper surface of the semiconductor wafer W is ground by a preset cutting allowance on each chuck mechanism 2. It is a thing.

The semiconductor wafer W is transferred to the wafer transfer arm 1
6 is accurately set on the chuck mechanism 2 and is vacuum-adsorbed to the chuck mechanism 2. The semiconductor wafer W is moved to the next processing position by rotating the rotary table 1 together with the chuck mechanism 2. Migrated,
Grinding to a predetermined required thickness at each processing position, and when the processing is completed, the spindle shaft 6 is raised and again,
When the rotary table 1 is rotated, it is carried to the next stop position, another spindle shaft 6 descends at the stop position, is sequentially ground, and is cleaned at the cleaning position. The rotary table 1 keeps a constant stop time. While rotating intermittently and endlessly.

The semiconductor wafer W is finally subjected to finish grinding and cleaned, and thereafter, the suction pad 1 of the wafer transfer arm 18 is operated by the action opposite to that of the wafer transfer arm 16 described above.
9 Adsorbed, washed and dried by the washing / drying device 20, placed on the storage-side transport belt 23 by the suction pad 22 provided on the storage-side reversing arm 21, and a ladder type provided on the side wall of the storage-side cassette 24. The cassettes 24 are lifted up and down in the partition frame, and are individually stored again for each individual product.

The surface automatic grinding machine for carrying out the present invention is configured in this way, and the above-described operation is automatically and regularly repeated so that the semiconductor wafers W delivered from the delivery side cassette 11 are successively moved to movable positions. To be guided, ground, cleaned and stored.

That is, the rotary table 1 of the automatic surface grinder is intermittently rotated and stopped repeatedly, and a plurality of chuck mechanisms 2 are fitted to each other with their top surfaces projected. The chuck mechanisms 2 are shared by the rotary drive source of the rotary table 1 and rotate independently of each other, and a vacuum pump is provided by a ventilation system penetrating the rotary table 1. When the semiconductor wafer W is securely vacuum-adsorbed to the upper surface of the chuck mechanism 2 by the vacuum mechanism, the cup wheel type grinding wheel 3 fixed to the lower end of the spindle shaft 6 from above the chuck mechanism 2 is connected to the vacuum mechanism. It descends and starts grinding.

The spindle shaft 6 is moved up and down to the base body 4
2 is supported by the drive source of the electric motor 7 to rotate by itself, and the cup wheel type grinding wheel 3 is also rotated accordingly. As shown in FIG.
Installed on the rotary shaft 4a of the electric motor 7 and the rotation adjusting mechanism 4b.
Is a spindle shaft 6 provided with a rod-shaped thread 4c interposed therebetween and having a guide 4d having a female screw threadedly engaged with the thread 4c, and a minute speed at which a brittle semiconductor wafer W is not damaged by grinding. It can be adjusted.

The axis of rotation a of the chuck mechanism 2 and the axis of rotation b of the spindle shaft 6 are maintained in a substantially parallel state, that is, the upper surface of the semiconductor wafer W and the grinding surface of the cup wheel type grinding wheel 3. Both are in a substantially parallel state,
The substantially parallel state means that the grinding surface of the cup wheel type grinding wheel 3 and the upper surface of the semiconductor wafer W are slightly tilted to reduce the grinding resistance, and that small protrusions are not left on the center of rotation of the semiconductor wafer W. The spindle shaft 6 is slightly oscillated, and the grinding surface of the cup wheel type grinding wheel 3 passes through at least the center point of the semiconductor wafer W. Symbol b is arranged at a constant interval to make the peripheral speed constant in the interference region during grinding between the ground surface of the cup wheel type grinding wheel 3 and the upper surface of the semiconductor wafer W to be ground.

Each of the motors 7 used in the present invention
In this embodiment, a power storage circuit 9 for each power source 8 is provided with a storage capacitor 9a, respectively. In the embodiment, as shown in FIG. 3, the motor 7 itself has a capacitor 9a incorporated in advance. 7, a switch 9b, a fuse 9c, an electromagnetic contactor 9d, and a thermal relay 9e are installed in a power supply circuit 9 which obtains electric power from an AC power supply 8, and in addition, a capacitor 9a for storing electricity is installed. When the power supply is stopped for some reason, the power stored in the capacitor 9a is transferred to the thermal relay 9e.
To switch the polarity of the motor 7
When the motor 7 of the elevating mechanism 4 is also rotated in reverse and the spindle shaft 6 is raised, the cup wheel type grinding wheel 3 fixed to the lower end is detached from the upper surface of the semiconductor wafer W, resulting in an unexpected power failure. Also, it is possible to deal with the grinding process of the semiconductor wafer W whose diameter has been expanded and ultrathin without leaving any damage, and the storage capacity of the capacitor 9a is from the upper surface of the semiconductor wafer W to the cup wheel type grinding wheel 3 It does not matter if it can be separated.

In the above description, the retract mechanism of the present invention has been described for the rotary type rotary table, but the present invention is not limited to this and can be applied to a chuck mechanism such as an index type index table.

[0019]

The effects of the present invention are as follows.
Even if a power failure occurs while grinding a semiconductor wafer with an automatic surface grinder, each motor electrode is switched and the electric power stored in the capacitor causes the motor to rotate in the reverse direction and the cup wheel type grinding wheel applied to the upper surface of the semiconductor wafer. In order to be released from the pressure of, the diameter expansion and ultra thinning are required,
In addition, it is an epoch-making mechanism that can continue the recovery or the grinding process again without leaving any damage on the semiconductor wafer having the brittle property, has a high reliability, and can exhibit a very significant effect.

[0020]

[Brief description of drawings]

FIG. 1 is a schematic plan view for explaining an automatic surface grinder using a rotary table according to an embodiment of the present invention.

FIG. 2 is a schematic side view of the present invention.

FIG. 3 is a schematic diagram of a motor including a capacitor.

[0021]

[Explanation of symbols]

 W Semiconductor wafer a Rotating shaft core of chuck mechanism b Spindle shaft rotating shaft core 1 Table 2 Chuck mechanism 3 Cup wheel type grinding wheel 4 Lifting means 4a Rotating shaft 4b Rotation adjusting mechanism 4c Screw 4d Guide 5 Base 6 Spindle shaft 7 Electric motor 8 power supply 9 power supply circuit 9a capacitor 9b switch 9c fuse 9d electromagnetic contactor 9e thermal relay 11 delivery side cassette 12 delivery side transfer belt 13 delivery side reversing arm 14 suction pad 15 preposition 16 wafer transfer arm 17 suction pad 18 wafer transfer arm 19 Suction pad 20 Washing / drying device 21 Storing side reversing arm 22 Suction pad 23 Storing side conveyor belt 24 Storing side cassette

Claims (1)

[Claims] 1. A chuck mechanism that is fitted to a table and rotates by itself, a semiconductor wafer that is vacuum-sucked to the chuck mechanism, and a cup-wheel type grinding device provided above to grind an upper surface of the semiconductor wafer. A grindstone, and a spindle shaft which is fixed to the lower end of the cup wheel type grinding grindstone and is rotatably supported by a base body through an elevating means, and which rotates on its own axis; and a rotary shaft core of the chuck mechanism and the spindle shaft. In an automatic surface grinder in which the rotation axis is substantially parallel to each other and the grinding surface of the cup wheel type grinding wheel is arranged with a constant interval passing at least the center point of the semiconductor wafer, the elevating means includes a motor. As a drive source, a cup wheel type grinding wheel is moved down at a constant fine speed to grind a set amount of cutting allowance on the upper surface of the semiconductor wafer, and the spindle shaft is rotated by a motor. The motor is rotating with the power source as a drive source, and a capacitor for storing electricity is inserted in the power supply circuit between each of the motors and each of the power sources, and the polarity of the motor is switched by the electric power stored in the capacitor during a power failure. A retractor mechanism for a grinding machine characterized by reverse rotation.