US-12617054-B2 - Creep feed grinding apparatus

US12617054B2US 12617054 B2US12617054 B2US 12617054B2US-12617054-B2

Abstract

A creep feed grinding apparatus includes a chuck table, a grinding unit having a spindle and a grinding wheel mounted on a lower end of the spindle, the grinding wheel including a plurality of grindstones disposed in an annular array on a surface of an annular base, the grindstones following an annular track upon rotation of the spindle, a moving mechanism for moving the chuck table and the grinding unit relative to each other along a predetermined direction perpendicular to the longitudinal axis of the spindle, and a bottom surface state adjusting mechanism for adjusting states of bottom surfaces of the grindstones by cleaning and/or correcting the bottom surfaces of the grindstones. The bottom surface state adjusting mechanism is positioned outside of a relative movement area of the chick table in which the chuck table and the grinding unit are moved relative to each other by the moving mechanism.

Inventors

Keisuke Nakano
Satoshi Yamanaka
Ryo Shimazu

Assignees

DISCO CORPORATION

Dates

Publication Date: 20260505
Application Date: 20221109
Priority Date: 20211122

Claims (10)

1 . A creep feed grinding apparatus comprising: a chuck table having a holding surface for holding a workpiece under suction thereon; a grinding unit having a spindle rotatable about a longitudinal axis thereof and a grinding wheel mounted on a lower end of the spindle, the grinding wheel including an annular base and a plurality of grindstones disposed in an annular array on a surface of the annular base, the grinding wheel including an annular track having an outside diameter larger than a diameter of the chuck table, the grindstones being in the annular track; a moving mechanism for moving the chuck table and the grinding unit relative to each other along a X-direction, which is perpendicular to the longitudinal axis of the spindle; and a bottom surface state adjusting mechanism for adjusting states of bottom surfaces of the grindstones by cleaning, correcting or cleaning and correcting the bottom surfaces of the grindstones that are held in contact with the workpiece on the holding surface when the grinding unit grinds the workpiece in a creep feed grinding mode, the bottom surface state adjusting mechanism having a longitudinal axis and being positioned below the annular track so that the longitudinal axis of the bottom surface adjusting mechanism is transverse to the bottom surfaces of the grindstones, wherein the bottom surface adjusting mechanism is positioned outside of a relative movement area of the chuck table in which the chuck table and the grinding unit are moved in the X-direction by the moving mechanism between a first position in which the chuck table is separated from the grinding wheel and a second position in which the chuck table is completely under the grinding wheel and the grindstones are contacting the workpiece, and the bottom surface adjusting mechanism is outside of the chuck table in the first position and the second position.
2 . The creep feed grinding apparatus according to claim 1 , wherein the bottom surface state adjusting mechanism has a nozzle for ejecting high-pressure water to the bottom surfaces of the grindstones when the grinding unit grinds the workpiece in the creep feed grinding mode.
3 . The creep feed grinding apparatus according to claim 1 , wherein the bottom surface state adjusting mechanism has a nozzle for ejecting high-pressure water including abrasive grains to the bottom surfaces of the grindstones when the grinding unit grinds the workpiece in the creep feed grinding mode.
4 . The creep feed grinding apparatus according to claim 1 , wherein the bottom surface state adjusting mechanism has a nozzle for ejecting a two-fluid mixture of water and air to the bottom surfaces of the grindstones when the grinding unit grinds the workpiece in the creep feed grinding mode.
5 . The creep feed grinding apparatus according to claim 1 , wherein the bottom surface state adjusting mechanism has a dresser configured for contacting the bottom surfaces of the grindstones when the grinding unit grinds the workpiece in the creep feed grinding mode.
6 . The creep feed grinding apparatus according to claim 1 , wherein the bottom surface state adjusting mechanism has a brush for contact with the bottom surfaces of the grindstones when the grinding unit grinds the workpiece in the creep feed grinding mode.
7 . The creep feed grinding apparatus according to claim 1 , wherein the bottom surface state adjusting mechanism has a laser beam applying unit including a beam condenser for applying a laser beam to the bottom surfaces of the grindstones when the grinding unit grinds the workpiece in the creep feed grinding mode.
8 . The creep feed grinding apparatus according to claim 1 , wherein the bottom surface state adjusting mechanism includes two nozzles disposed diametrically across the center on an outside diameter of a grinding surface of the grinding wheel and outside of a relative movement area of the chuck table.
9 . The creep feed grinding apparatus according to claim 1 , wherein the bottom surface state adjusting mechanism includes a nozzle that is disposed on a straight line parallel to a Y-axis and across a center of the workpiece on a X-Y plane.
10 . The creep feed grinding apparatus according to claim 1 , wherein the grinding unit is attached to a support structure, the support structure being attached to an X-axis moving mechanism that moves the support structure along the X-axis.

Description

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a creep feed grinding apparatus for grinding a workpiece with a grinding wheel while a grinding unit having a spindle with the grinding wheel mounted on a lower end thereof and a chuck table holding the workpiece under suction thereon are being moved relative to each other in a direction perpendicular to the longitudinal axis of the spindle. Description of the Related Art Pieces of electronic equipment such as cellular phones and personal computers typically incorporate device chips having such devices as integrated circuits (ICs). Device chips are manufactured as follows: First, a plurality of projected dicing lines or streets are established in a grid pattern on the face side of a wafer made of a semiconductor such as silicon, and devices are formed in respective rectangular areas demarcated on the face side of the wafer by the projected dicing lines. Then, a cutting apparatus is used to cut the wafer along the streets into individual pieces as device chips. In recent years, it has been customary to grind the reverse side of a wafer after devices have been formed on the face side thereof, thereby reducing the finished thickness of device chips to be produced from the wafer, with a view to reducing the size and weight of the device chips. Wafers are ground using a creep feed grinding apparatus, for example (see Japanese Patent Laid-open No. 2010-103192). The creep feed grinding apparatus includes a chuck table having a holding surface for holding a workpiece, i.e., a wafer, under suction thereon. The creep feed grinding apparatus also includes a grinding unit disposed above the holding surface. The grinding unit has a cylindrical spindle whose longitudinal axis extends substantially perpendicularly to the holding surface. Usually, the longitudinal axis of the spindle lies substantially parallel to a Z-axis of the creep feed grinding apparatus, e.g., a vertical axis. The spindle has a lower end on which there is mounted an annular grinding wheel by a circular plate mount interposed therebetween. The grinding wheel has an annular base whose lower surface supports thereon an annular array of grindstones spaced at substantially equal intervals along circumferential directions of the annular base. When the spindle is rotated about its central axis, i.e., its longitudinal axis, the grinding wheel is also rotated about its central axis, enabling the grindstones to provide an annular grinding surface along an annular track made up of the lower surfaces of the grindstones as they rotate in unison with the grinding wheel. In order for the creep feed grinding apparatus to operate in a creep feed grinding mode, the workpiece has its face side held under suction on the holding surface with its reverse side exposed upwardly, and the grinding unit is adjusted in its vertical position or height such that the annular grinding surface is slightly lower than the exposed reverse side of the workpiece. Then, the chuck table is moved along an X-axis perpendicular to the Z-axis to cause the grindstones to grind the reverse side of the workpiece in the creep feed grinding mode. In the creep feed grinding mode, the load applied along the X-axis to the outer side surfaces of the grindstones tends to be larger than the load applied along the Z-axis to bottom surfaces of the grindstones. By contrast, in an in-feed grinding mode in which the grinding unit is processing-fed downwardly along the Z-axis while the chuck table disposed below the grinding unit is being rotated, the load applied along the Z-axis to the bottom surfaces of the grindstones tends to be larger than the load applied along the X-axis to the outer side surfaces of the grindstones. In the creep feed grinding mode, depending on the loads applied to the grindstones when the workpiece is ground, the bottom surfaces of the grindstones are liable to wear to a smaller extent than the bottom surfaces of the grindstones liable to wear in the in-feed grinding mode. In the creep feed grinding mode, hence, the bottom surfaces of the grindstones are likely to suffer a grindstone condition failure or malfunction such as grindstone loading. In particular, the bottom surfaces of the grindstones are more likely to suffer a grindstone condition failure when the grindstones grind a substrate of resin in the creep feed grinding mode. SUMMARY OF THE INVENTION Such a grindstone condition failure may be eliminated by a dressing step of dressing the grindstones in addition to a grinding step of grinding the workpiece in the creep feed grinding mode. However, the additional dressing step lowers the efficiency of grinding in the creep feed grinding mode. The present invention has been made in view of the above difficulties. It is an object of the present invention to provide a creep feed grinding apparatus that is capable of eliminating a grindstone condition failure at the bottom surfaces of grindstones with