CUTTING APPARATUS

A cutting apparatus includes a cutting liquid supply nozzle that is disposed adjacent to a cutting unit and supplies a cutting liquid to a contact point between a cutting blade and a workpiece and a chemical liquid supply nozzle that has a length in a Y-axis direction which is greater than the width of the workpiece and supplies a chemical liquid for preventing adhesion of cutting swarf to a front surface of the workpiece.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a cutting apparatus for cutting a workpiece.

Description of the Related Art

A wafer formed on a front surface thereof with a plurality of devices such as integrated circuits (ICs) and large-scale integration (LSI) circuits in the state of being partitioned by a plurality of intersecting projected dicing line (streets) is divided into individual device chips by a cutting apparatus including a cutting blade in a rotatable manner, and the thus divided device chips are used for electric apparatuses such as mobile phones and personal computers.

The cutting apparatus includes a chuck table that holds a wafer, a cutting unit that includes, in a rotatable manner, a cutting blade for cutting the wafer held by the chuck table, an X-axis feeding mechanism for relative cutting-feeding of the chuck table and the cutting unit in an X-axis direction, and a Y-axis feeding mechanism for relative indexing-feeding of the chuck table and the cutting unit in a Y-axis direction, and can divide the wafer into individual device chips with high accuracy.

In addition, when the wafer is cut by the above-mentioned cutting blade, cutting swarf (contaminants) may float on and be adhered to the front surface of the wafer, thereby lowering the quality of the devices. In view of this, there has been proposed a technology of supplying cleaning water to the front surface of the wafer to wash away the cutting swarf and thereby prevent adhesion of the cutting swarf to the devices (refer to Japanese Patent Laid-open No. 2014-121738).

SUMMARY OF THE INVENTION

However, even when the cleaning water is supplied based on the technology described in the above-mentioned Japanese Patent Laid-open No. 2014-121738, it is difficult to efficiently wash away the cutting swarf, adhesion to the devices cannot be sufficiently prevented, and hence there is a demand for proposal of further solution.

Accordingly, it is an object of the present invention to provide a cutting apparatus that is able to efficiently prevent adhesion of cutting swarf to devices.

In accordance with an aspect of the present invention, there is provided a cutting apparatus including a chuck table that holds a workpiece, a cutting unit having, in a rotatable manner, a cutting blade for cutting the workpiece held by the chuck table, an X-axis feeding mechanism for relative cutting-feeding of the chuck table and the cutting unit in an X-axis direction, a Y-axis feeding mechanism for relative indexing-feeding of the chuck table and the cutting unit in a Y-axis direction orthogonal to the X-axis direction, a cutting liquid supply nozzle that is disposed adjacent to the cutting unit and supplies a cutting liquid to a contact point between the cutting blade and the workpiece, and a chemical liquid supply nozzle that has a length in the Y-axis direction which is greater than a width of the workpiece and supplies a chemical liquid for preventing adhesion of cutting swarf to a front surface of the workpiece.

Preferably, the cutting liquid supply nozzle supplies pure water or an aqueous solution of a neutral surface active agent, and the chemical liquid supply nozzle supplies any one of ammonia and aqueous hydrogen peroxide, a citric acid solution, sulfuric acid and aqueous hydrogen peroxide, ozone water, phosphoric acid and buffered hydrofluoric acid, and a phosphoric acid solution.

According to the cutting apparatus of the present invention, cutting swarf can be efficiently washed away from the front surface of the workpiece, and, further, lubricating properties and cooling properties for a cutting edge of the cutting blade can be maintained while corrosion of the cutting edge is prevented.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A cutting apparatus according to an embodiment of the present invention will be described in detail below with reference to the attached drawings.FIG.1depicts a general perspective view of a cutting apparatus1according to the present embodiment. A workpiece to be processed by the cutting apparatus1is, for example, a wafer W formed of silicon (Si).

The cutting apparatus1includes a cassette4(depicted in long and two short dashes line) that accommodates a plurality of wafers W as workpieces, a temporary placement table5on which the wafer W accommodated in the cassette4is conveyed out and temporarily placed, a conveying-in/out unit6that conveys out the wafer W from the cassette4onto the temporary placement table5and conveys in the wafer W from the temporary placement table5into the cassette4, a conveying mechanism7that sucks the wafer W conveyed out onto the temporary placement table5, swivels the wafer W, and places the wafer W on a holding surface8bof a chuck table8aof a holding unit8, a cutting unit9that cuts the wafer W held under suction by the holding surface8bof the chuck table8a, a cleaning unit10(details are omitted) that cleans the wafer W cut by the cutting unit9, a cleaning conveying mechanism11that conveys the cut wafer W from the chuck table8ato the cleaning unit10, an imaging unit12that images the wafer W on the chuck table8a, and an unillustrated controller. The cassette4is mounted on a cassette table4adisposed to be vertically movable by an unillustrated lifting mechanism, and, at the time of conveying out the wafer W from the cassette4by the conveying-in/out unit6, the height of the cassette4is adjusted as required. Inside an apparatus housing2, there are disposed an X-axis feeding mechanism for processing-feeding of the chuck table8aof the holding unit8in an X-axis direction and a Y-axis feeding mechanism (both omitted in illustration) for indexing-feeding of the cutting unit9in a Y-axis direction orthogonal to the X-axis direction.

With reference toFIG.2, the cutting unit9disposed in the cutting apparatus1depicted inFIG.1will be described specifically.FIG.2is a perspective view depicting, in an enlarged form, an essential part of the cutting unit9of the cutting apparatus1depicted inFIG.1and the holding unit8moved to a position directly under the cutting unit9. As understood fromFIG.2, the cutting unit9includes a rotary shaft housing91extending in the Y-axis direction, a rotary shaft92rotatably supported by the rotary shaft housing91, an annular cutting blade93detachably supported on a tip end side of the rotary shaft92, a cover94that is mounted to the tip of the rotary shaft housing91and that covers the cutting blade93, a cutting liquid supply nozzle95(depicted in broken line) that supplies a cutting liquid L2to a contact point between the cutting blade93and the wafer W, that is, the cutting position, and a chemical liquid supply nozzle96that supplies a chemical liquid L1(described in detail later) for preventing adhesion of cutting swarf to a front surface Wa of the wafer W. Note that the rotary shaft92is driven to be rotated by an unillustrated electric motor disposed on a rear end side of the rotary shaft92. In addition, the cutting unit9in the present embodiment also includes a cutting-in feeding mechanism (omitted in illustration) that moves the cutting unit9in a Z-axis direction to perform cutting-in feeding, in addition to the above-mentioned Y-axis feeding mechanism.

As depicted inFIG.2, the cover94includes a first cover member94afixed to the tip of the rotary shaft housing91, a second cover member94bfixed by a screw to a front surface of the first cover member94a, and a cutting blade detection block94cfixed by screws from an upper surface of the first cover member94a. A blade sensor (omitted in illustration) for detecting wear or chipping on an outer circumferential edge part side of the cutting blade93is disposed in the cutting blade detection block94c.

The chemical liquid supply nozzle96is disposed adjacent to the cutting unit9. In the present embodiment, the chemical liquid supply nozzle96includes a hollow cylindrical main body section96adisposed along the Y-axis direction, a plurality of jet holes96bwhich are disposed in the main body section96atoward the lower side on the cutting blade93side and which jet the chemical liquid L1toward the wafer W held by the chuck table8a, and a chemical liquid introduction port96cformed at an end part on the depth side of the main body section96a. A chemical liquid supply unit13for supplying the chemical liquid L1is connected to the chemical liquid introduction port96c. The chemical liquid supply nozzle96is fixed to the cover94or the rotary shaft housing91by an unillustrated fixing member or members, and is moved as one body with the cutting unit9.

The chemical liquid supply unit13includes a chemical liquid storage tank13athat stores the chemical liquid L1, a chemical liquid passage13bthat connects the chemical liquid storage tank13aand the chemical liquid introduction port96c, and an on-off valve13cfor closing and opening the chemical liquid passage13b. The chemical liquid storage tank13aincludes an unillustrated pump, and, by operating the pump and opening the on-off valve13c, the chemical liquid L1can be jetted through the jet holes96bof the chemical liquid supply nozzle96.

The cutting liquid supply nozzle95depicted in broken line inFIG.2is disposed adjacent to the cutting unit9. In the present embodiment, the cutting liquid supply nozzle95is formed inside the first cover member94a, and supplies the cutting liquid L2introduced via a cutting liquid introduction port95a, toward the contact point of the cutting blade93and the wafer W to be cut. A cutting liquid supply unit14is connected to the cutting liquid introduction port95a. The cutting liquid supply unit14includes a cutting liquid storage tank14athat stores the cutting liquid L2, a cutting liquid passage14bthat connects the cutting liquid storage tank14aand the cutting liquid introduction port95a, and an on-off valve14cfor closing and opening the cutting liquid passage14b. The cutting liquid storage tank14aincludes an unillustrated pump, and, by operating the pump and opening the on-off valve14c, the cutting liquid L2can be jetted from a jet port95bof the cutting liquid supply nozzle95.

The chemical liquid L1in the present embodiment will be described below. The chemical liquid L1adopted in the present invention is a chemical liquid which is used for a main purpose of preventing adhesion of cutting swarf generated by cutting to the front surface of the workpiece (in the present embodiment, the wafer W of silicon). Various chemical liquids having different effects as set forth below can be adopted according to the cutting conditions and the status of the workpiece. Note that the chemical liquid to be adopted in the present invention is not limited to Chemical Liquids 1 to 6 described below, and any chemical liquid that prevents adhesion of the cutting swarf generated by cutting to the front surface of the workpiece is not excluded from the present invention.

Mixed water of ammonia and aqueous hydrogen peroxide: excellent in removal of particles.

A citric acid solution: excellent in removal of heavy metal elements.

Mixed water of sulfuric acid and aqueous hydrogen peroxide: excellent in removal of organic matter.

Ozone water: excellent in removal of metals and organic matter.

A mixed liquid of phosphoric acid and buffered hydrofluoric acid: excellent in removal of particles of insulating films.

A phosphoric acid solution: excellent in removal of metallic impurities. When this solution is used, its temperature is raised to 35° C. to 50° C.

The above-described chemical liquid supply nozzle96is for supplying the chemical liquid L1such that the cutting swarf scattered on the front surface Wa of the wafer W held by the chuck table8aduring cutting would not be adhered, and in the chemical liquid supply nozzle96and the wafer W held by the above-mentioned chuck table8aare set to satisfy the following conditions described based onFIG.3. Note thatFIG.3is a plan view depicting the wafer W held by the chuck table8aof the holding unit8and the chemical liquid supply nozzle96disposed in the cutting unit9, in which, for convenience of explanation, those configurations of the cutting unit9which are other than the chemical liquid supply nozzle96(the cover94, the rotary shaft housing81, and the like) are omitted. The wafer W is a wafer formed on its front surface Wa with a plurality of devices Wd in the state of being partitioned by streets We, and the wafer W is held by an annular frame F having an opening Fa capable of accommodating the wafer W, with an adhesive tape T therebetween.

As understood from the plan view ofFIG.3, the chemical liquid supply nozzle96is disposed along the Y-axis direction, and has a length in the Y-axis direction which is greater than a width P1in the Y-axis direction of the workpiece (in the present embodiment, the wafer W). In addition, in a case where the plurality of jet holes96bformed in the main body section96aof the chemical liquid supply nozzle96are not present over the whole region in the longitudinal direction of the main body section96a, a length P2defined by the jet hole96bat an end part on one side and the jet hole96bat an end part on the other side is set to be longer than the width P1of the workpiece, as depicted inFIG.3. Further, the number and the intervals of the plurality of jet holes96bformed are set in such a manner that the chemical liquid L1is supplied through the jet holes96bto the whole region in the width direction of the workpiece held by the chuck table8a. Note that, in the above-described embodiment, the chemical liquid supply nozzle96is formed with the plurality of jet holes96bto supply the chemical liquid L1therethrough, but the present invention is not limited to this configuration, and the chemical liquid L1may be supplied through a slit formed along the longitudinal direction of the chemical liquid supply nozzle96. In this case, the length of the slit is set in a size greater than the length of the width P1of the above-mentioned workpiece. The chemical liquid supply unit13, the cutting liquid supply unit14, and each operating section described above are controlled by the above-mentioned controller.

The cutting apparatus1of the present embodiment is configured substantially as described above, and a mode of cutting the wafer W as a workpiece by the cutting apparatus1will be described below. Note that the workpiece in the present invention is the plate-shaped wafer W as depicted inFIG.4, which is formed with the plurality of devices Wd on the front surface Wa thereof partitioned by the streets We.

At the time of performing cutting by the cutting unit9of the cutting apparatus1described based onFIG.1, first, the wafer W accommodated in the cassette4is conveyed out onto the temporary placement table5by the conveying-in/out unit6, and is conveyed onto the chuck table8apositioned at the conveying-in/out position inFIG.1, by the conveying mechanism7. After the wafer W is mounted on the chuck table8aand held under suction, the wafer W is positioned at a position directly under the imaging unit12by the X-axis feeding mechanism omitted in illustration and is imaged, and a predetermined street We extending in a first direction of the wafer W in a region to be cut is detected and is matched to the X-axis direction. Next, alignment of the street We at which cutting is to be started and the cutting blade93of the cutting unit9is conducted, and the cutting unit9is positioned at a predetermined processing start position.

Subsequently, as depicted inFIG.4, the cutting blade93of the cutting unit9is rotated at high speed in the direction indicated by an arrow R1and is positioned on the street We having been matched to the X-axis direction, then the above-mentioned chemical liquid supply unit13and cutting liquid supply unit14are operated to jet the chemical liquid L1and the cutting liquid L2from the chemical liquid supply nozzle96and the cutting liquid supply nozzle95, respectively. Then, the above-mentioned cutting-in feeding mechanism is operated to cause the cutting blade93to cut into the wafer W in the Z-axis direction from the front surface Wa side of the wafer W, and the above-mentioned X-axis feeding mechanism is operated to put the wafer W into processing-feeding in the X-axis direction indicated by an arrow X inFIG.4, thereby forming a cut groove100.

A front view of the cutting for forming the above-mentioned cut groove100according to the embodiment is depicted inFIG.5. InFIG.5, for convenience of explanation, the second cover member94band the cutting blade detection block94cof the cover94are omitted, and a part of the first cover member94aformed with the cutting liquid supply nozzle95is depicted in section.

As understood fromFIGS.4and5, the above-mentioned chemical liquid L1is supplied onto the front surface Wa of the wafer W from the jet holes96bof the chemical liquid supply nozzle96of the chemical liquid supply unit13, so that the cutting swarf (contaminants) scattered from the contact point between the cutting blade93and the wafer W during formation of the cut groove100is prevented from being adhered to the front surface Wa of the wafer W. Incidentally, there is a fear that a bonding agent (for example, nickel plating) constituting the cutting edge of the cutting blade93is corroded due to the influence of this chemical liquid L1, thereby lowering the quality of cutting. In the present embodiment, however, the cutting liquid L2is supplied from the cutting liquid supply nozzle95toward the contact point between the cutting blade93and the wafer W as the workpiece. As a result, corrosion of the cutting edge which might be generated under the influence of the chemical liquid L1supplied onto the front surface Wa of the wafer W can be prevented. As the cutting liquid L2, for example, either pure water or a neutral surface active agent solution is preferably selected, and, as a result, corrosion of the cutting edge of the cutting blade93can be prevented, and lubricating properties and cooling properties for the cutting edge can be maintained. Note that, as the neutral surface active agent, there can be used, for example, a fatty acid salt, a synthetic detergent, and the like.

After the above-mentioned cut groove100is formed, the cutting blade93of the cutting unit9is put to indexing-feeding onto an unprocessed street We which extends in the first direction and which is adjacent in the Y-axis direction to the street We formed with the cut groove100, and the cut groove100is formed similarly to the above. By repeating these operations, the cut grooves100are formed along all the streets We extending in the first direction. Next, the wafer W is rotated by 90 degrees, to match the streets We extending in a second direction orthogonal to the first direction to the X-axis direction, and, while the above-mentioned chemical liquid L1and cutting liquid L2are supplied, cutting is carried out on all the streets We extending in the second direction, whereby the cut grooves100are formed along all the streets We formed on the wafer W. By the above operations, the devices Wd of the wafer W are divided into individual device chips.

According to the cutting apparatus1of the embodiment described above, the cutting swarf can be efficiently washed away from the front surface Wa of the wafer W, the lubricating properties and cooling properties for the cutting edge of the cutting blade93can be maintained while corrosion of the cutting edge is prevented, and the wafer W can be divided along the streets We into the individual device chips.