JP7634600B2 - Grinding Equipment - Google Patents

Description

The present invention relates to a grinding device that grinds wafers with a grinding wheel.

In the semiconductor manufacturing field, back grinding is performed to grind the back side of semiconductor wafers such as silicon wafers (hereafter referred to as "wafers") to form them into a thin film.

Patent Document 1 discloses a grinding device 10 that grinds the top surface of a wafer W held by suction on a chuck table 11 with a grinding wheel 12 while grinding water (cooling water) is supplied between the grinding wheel 12 and the wafer W from a nozzle provided at the tip of a coolant supply mechanism 17.

The coolant supply mechanism 17 is installed on the side of a chamber that houses an arm-shaped sensor movement mechanism 18 carrying a non-contact sensor 15, a contact sensor, and the like. The nozzle of the coolant supply mechanism 17 is connected to a flexible hose, and is configured so that the position at which the grinding water is supplied can be changed as desired. The reference numerals are those in Patent Document 1.

JP 2016-184604 A

However, in the grinding device 10 described in Patent Document 1, various devices are arranged in a small chamber, so that during maintenance work, the flexible hose must be bent to move the nozzle away from the vicinity of the grinding wheel 12, which tends to make the maintenance work complicated. In addition, because the operator must manually bend the flexible hose to adjust the nozzle position, there is a problem that the grinding water discharge position may not be constant.

Therefore, a technical problem arises that must be solved in order to perform maintenance work efficiently and to eject grinding water to a specific location to efficiently cool the wafer and grinding wheel, and the present invention aims to solve this problem.

In order to achieve the above object, a grinding apparatus according to the present invention includes a chuck for suction-holding a wafer, a spindle having a grinding wheel for grinding the wafer attached to its lower end and disposed above the chuck and capable of being raised and lowered, a jacket for accommodating the spindle and disposed so as to be capable of being raised and lowered, and a grinding water supply mechanism having a plurality of nozzles disposed integrally with the jacket and capable of being raised and lowered, the plurality of nozzles having a fixed direction for discharging the grinding water so as to discharge the grinding water at a fixed position , The number of nozzles includes at least one first nozzle arranged corresponding to a first position within the chuck and at least one second nozzle arranged corresponding to a second position within the chuck closer to a processing line where the grinding wheel contacts the wafer than the first position, the first position corresponding to a down-cut processing line where the grinding wheel grinds the wafer from the center of the wafer toward the outer periphery, and the second position corresponding to an up-cut processing line where the grinding wheel grinds the wafer from the outer periphery of the wafer toward the center.

With this configuration, the nozzle is configured to be able to rise and fall as one unit with the jacket, so that the nozzle does not interfere with the operator's work space during maintenance, allowing maintenance work to be carried out efficiently. In addition, there is no need to change the direction of the nozzle each time maintenance is performed, so grinding water can be discharged to a fixed location.

In the present invention, the nozzle is configured to be raised and lowered integrally with the jacket, so that the nozzle does not interfere with the operator's work space during maintenance, allowing maintenance work to be carried out efficiently. In addition, since there is no need to change the direction of the nozzle each time maintenance is performed, grinding water can be discharged to a fixed location.

1 is a plan view of a grinding device according to an embodiment of the present invention, viewed from above; FIG. FIG. 3 is an enlarged perspective view of a main portion of FIG. 2 . FIG. 3A and 3B are a plan view and a side view showing a schematic diagram of down-cutting. 3A and 3B are a plan view and a side view, respectively, which show a schematic diagram of an upcut.

The embodiment of the present invention will be described with reference to the drawings. Note that in the following, when referring to the number, numerical value, amount, range, etc. of components, unless otherwise specified or when it is clearly limited to a specific number in principle, it is not limited to that specific number, and it may be more or less than the specific number.

In addition, when referring to the shape or positional relationship of components, etc., this includes things that are substantially similar or similar to that shape, etc., unless otherwise specified or considered in principle to be clearly different.

In addition, drawings may exaggerate characteristic parts to make the features easier to understand, and the dimensional ratios of components may not be the same as in reality. In addition, in cross-sectional views, hatching of some components may be omitted to make the cross-sectional structure of the components easier to understand.

The grinding device 1 grinds one surface (the surface to be processed) of a wafer W into a flat surface. The grinding device 1 is divided into one or more chambers C according to the process. By providing multiple chambers C, multiple wafers W can be processed continuously. Figure 1 is a plan view showing the configuration inside the chamber C. Figure 2 is a perspective view showing the grinding device 1.

The grinding device 1 includes an index table 10 and a chuck 11 that is arranged on the index table 10 and holds the other side of the wafer W by suction.

The index table 10 is rotatable around a rotation axis 12, and multiple chucks 11 are arranged concentrically at equal intervals around the rotation axis 12.

The chuck 11 has an adsorbent (not shown) made of a porous material such as alumina embedded in its upper surface. The chuck 11 has a conduit (not shown) that runs through the inside and reaches the surface. The conduit is connected to a vacuum source, a compressed air source, or a water supply source via a rotary joint (not shown). When the vacuum source is activated, the wafer W placed on the chuck 11 is adsorbed and held by the chuck 11. When the compressed air source or water supply source is activated, the adsorption between the wafer W and the chuck 11 is released.

The grinding device 1 also includes a grinding wheel 20, a spindle 21, and a spindle feed mechanism 22. The grinding wheel 20 is, for example, a cup-shaped grinding wheel. The grinding wheel 20 is attached to the lower end of the spindle 21. The spindle 21 is configured to be rotatable together with the grinding wheel 20.

The spindle feed mechanism 22 is configured to raise and lower the jacket 23 that houses the spindle 21 in the vertical direction (the up and down direction on the paper in FIG. 2). The spindle feed mechanism 22 includes two linear guides 25 that connect the jacket 23 and the column 24, and a known ball screw slider mechanism 26 that raises and lowers the jacket 23 in the vertical direction.

A fixed thickness gauge 30 and a mobile thickness gauge 40 are provided in chamber C.

The fixed thickness gauge 30 measures the wafer thickness at a fixed point at a predetermined radial position on the wafer W. The fixed thickness gauge 30 is equipped with a pair of sensor heads 31, 32. The sensor head 31 is arranged so that it can contact the upper surface of the wafer W, and measures the height of the lower end of the sensor head 31. The sensor head 32 is arranged outside the sensor head 31, arranged so that it can contact the upper surface of the chuck 11, and measures the height of the lower end of the sensor head 32. The difference between the measured values of the sensor heads 31, 32 is the thickness of the wafer W.

The mobile thickness gauge 40 measures the thickness of the wafer W while moving in the radial direction on the wafer W. The mobile thickness gauge 40 includes a sensor 41 and an arm 42 with the sensor 41 attached at its tip.

Sensor 41 is a film thickness sensor that measures the thickness of the wafer W in a non-contact manner during grinding. For example, a spectral interference film thickness sensor is preferable for sensor 41. A spectral interference film thickness sensor is resistant to external disturbances such as vibrations, and can measure the thickness of the wafer W with high accuracy. The following describes an example in which a spectral interference film thickness sensor is used as sensor 41.

The sensor head (not shown) of the sensor 41 irradiates light toward the wafer W and receives reflected light resulting from interference between the light reflected on the upper and lower surfaces of the wafer W. The reflected light is split by a spectroscope, and a control device (described later) calculates the thickness of the wafer W based on the optical path difference between the light reflected on the upper surface of the wafer W and the light reflected on the lower surface of the wafer W.

The arm 42 can swing in the radial direction of the wafer W, with the drive shaft 43 as a fulcrum. The arm 42 can swing so that the sensor 41 can scan from the outer edge of the wafer W to a position that does not interfere with the grinding wheel 20.

The fixed thickness gauge 30 and the mobile thickness gauge 40 are located on opposite sides of the spindle 21 from the opening O through which the operator accesses the chamber C when performing maintenance work.

The grinding water supply mechanism 50 supplies grinding water (cooling water) between the grinding wheel 20 and the wafer W. The specific configuration of the grinding water supply mechanism 50 will be described later.

The operation of the grinding device 1 is controlled by a control device (not shown). The control device controls each of the components that make up the grinding device 1. The control device is, for example, a computer, and is composed of a CPU, memory, etc. The functions of the control device may be realized by controlling it using software, or may be realized by operating it using hardware.

Next, the specific configuration of the grinding water supply mechanism 50 will be described with reference to Figures 3 and 4.

The grinding water supply mechanism 50 includes a nozzle 51 protruding from the lower end of the jacket 23. The nozzle 51 has an outlet 52 facing downward. The nozzle 51 is connected to a pipe 53 through which the grinding water passes, and supplies the grinding water between the wafer W and the grinding wheel 20. Four nozzles 51 are provided along the rotation direction D of the grinding wheel 20. The number of nozzles 51 is not limited to four, and may be three or less, or five or more. Some of the pipes 53 are omitted in Figures 2 to 4.

A valve 54 is installed in the pipe 53 through which the grinding water passes, and is configured so that the grinding water can pass through either two nozzles 51 provided on one side of the rotation direction D (hereinafter collectively referred to as the "first nozzle group A") or two nozzles 51 provided on the other side of the rotation direction D (hereinafter collectively referred to as the "second nozzle group B").

The nozzle 51 is formed in a generally L-shape when viewed from the side. The nozzle 51 is also configured to be rigid (i.e., unable to bend) in the direction of the grinding water supply. This allows the nozzle 51 to supply grinding water to approximately the same position. The base end side of the nozzle 51 is also connected to the inside of the jacket 23 via a link mechanism 55. This allows the nozzle 51 to rotate around the link mechanism as a fulcrum, and the direction of the discharge port 52 can be finely adjusted, allowing the grinding wheel 20 and the wafer W to be cooled efficiently.

Next, the operation of the grinding device 1 will be explained with reference to the drawings.

First, the index table 10 rotates, and the chuck 11 that holds the wafer W by suction is transported into the chamber C and positioned below the grinding wheel 20. Then, the spindle feed mechanism 22 is driven to move the grinding wheel 20 close to the wafer W.

Next, grinding water is ejected from the first nozzle group A or the second nozzle group B to supply the grinding water between the wafer W and the grinding wheel 20.

Whether the grinding water is discharged from the first nozzle group A or the second nozzle group B is set according to the grinding conditions. For example, as shown in Figures 5(a) and (b), in the case of so-called down-cutting in which the grinding wheel 20 grinds the wafer W from the center of the wafer W toward the outer periphery, the grinding water is discharged from a location (first position) away from the processing line where the grinding wheel 20 contacts the wafer W in the rotation direction of the wafer W, so that the grinding water discharged onto the wafer W spreads throughout the processing line as the wafer W rotates. Therefore, in the case of down-cutting, the grinding water is discharged from the first nozzle group A arranged at the first position.

On the other hand, as shown in Figures 6(a) and (b), in the case of so-called up-cutting, in which the grinding wheel 20 grinds the wafer W from the outer periphery toward the center of the wafer W, more frictional heat is generated during grinding compared to down-cutting, in which the wafer W and the grinding wheel 20 rotate in the same direction, so it is necessary to eject the grinding water at a position (second location) closer to the processing line than the first position. Therefore, in the case of up-cutting, the grinding water is ejected from the second nozzle group B arranged at the second position.

In this way, the grinding water supply mechanism 50 can reduce the amount of grinding water used by ejecting grinding water from the nozzle 51, which can be cooled efficiently according to the grinding conditions.

Next, while rotating the chuck 11 and the grinding wheel 20, the grinding wheel 20 is pressed against the surface of the wafer W. The grinding conditions of the grinding device 1 are, for example, a rotation speed of the chuck 11 of 300 rpm, a grit size of the grinding wheel 20 of #6000, a rotation speed of the spindle 21 of 2000 rpm, and a feed speed of the spindle feed mechanism 22 of 0.4 μm/s.

The grinding device 1 grinds the wafer W until the measurement value of the fixed thickness gauge 30 reaches the desired thickness (e.g., 6 μm). When grinding of the wafer W is completed, the chuck 11 and grindstone 20 stop, the grindstone 20 retreats upward, and the index table 10 rotates to transport the ground wafer W to the next process (polishing, cleaning, etc.).

In this way, the grinding device 1 according to this embodiment is configured so that the nozzle 51 can be raised and lowered integrally with the jacket 23, and therefore the nozzle 51 does not interfere with the operator's work space during maintenance, allowing maintenance work to be carried out efficiently. In addition, since there is no need to change the orientation of the nozzle 51 each time maintenance is performed, grinding water can be discharged to a fixed location.

In addition, because the nozzle 51 is configured to be non-bendable, the grinding water discharged from the nozzle 51 is supplied stably to a fixed location.

The present invention can be modified in various ways without departing from the spirit of the invention, and it goes without saying that the present invention also covers such modifications.

REFERENCE SIGNS LIST 1 ... Grinding device 10 ... Index table 11 ... Chuck 12 ... Rotating shaft 20 ... Grinding wheel 21 ... Spindle 22 ... Spindle feed mechanism 23 ... Jacket 24 ... Column 25 ... Linear guide 26 ... Ball screw slider mechanism 30 ... Fixed thickness gauge 31, 32 ... Sensor head 40 ... Mobile thickness gauge 41 ... Sensor 42 ... Arm 43 ... Drive shaft 50 ... Grinding water supply mechanism 51 ... Nozzle 52 ... Discharge port 53 ... Piping 54 ... Valve 55 ... Link mechanism A ... First nozzle group B ... Second nozzle group C ... Chamber O ... Opening

Claims (3)

a chuck for suction-holding the wafer;
a spindle having a lower end attached with a grindstone for grinding the wafer, the spindle being disposed above the chuck and capable of ascending and descending;
A jacket that houses the spindle and is arranged to be liftable and lowerable;
a grinding water supply mechanism having a plurality of nozzles that are vertically movable and integral with the jacket and that discharge grinding water toward at least one of the wafer and the grindstone;
Equipped with
The plurality of nozzles are fixed in the direction in which the grinding water is discharged so as to discharge the grinding water to a fixed position ,
The plurality of nozzles includes at least one first nozzle disposed corresponding to a first position in the chuck, and at least one second nozzle disposed corresponding to a second position in the chuck closer to a processing line where the grinding wheel contacts the wafer than the first position;
the first position corresponds to a down-cut processing line in which the grindstone grinds the wafer from the center to the outer periphery of the wafer,
A grinding apparatus, characterized in that the second position corresponds to an up-cut processing line in which the grinding wheel grinds the wafer from the outer periphery toward the center of the wafer . The grinding device according to claim 1, characterized in that the nozzles are provided at the lower end of the outer side of the jacket. The grinding device according to claim 1 or 2, characterized in that the grinding water supply mechanism is configured to be able to switch among the multiple nozzles through which the grinding water passes, depending on the grinding conditions under which the grinding wheel grinds the wafer.