JP2010052062A - Grinding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately measure thickness and form into the desired thickness when grinding a projection part of the face of a workpiece formed with recesses and projections into the desired thickness. <P>SOLUTION: The method for grinding the face 10 of the workpiece 1 with a grinding tool 60 by affixing a back face 11 of the workpiece 1 formed with recesses and projections on its face to a holding member 2, and holding the holding member 2 side by the chuck table 5, includes a grinding process of affixing a measuring piece 4 to the holding member 2 adjacent to the workpiece 1, rotating the chuck table 5 holding the holding member 2, and grinding the measuring piece 4 with the grinding tool 60 together with the projection part 100 of the face 10 of the workpiece 1; and a thickness measurement process of measuring the thickness of the measuring piece 4 while rotation of the chuck table 5 is temporarily stopped. In the grinding process, the workpiece 1 is ground to the desired thickness based on the measurement value in the thickness measurement process. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a grinding method for grinding a surface of a workpiece having a concavo-convex portion on the surface to obtain a desired thickness.

  When various workpieces are thinned and ground to a desired thickness, grinding is performed while measuring the thickness of the workpiece, and the grinding is terminated when the desired thickness is reached. As a method of measuring the thickness of the workpiece, the contact of the thickness measuring instrument is brought into contact with the surface of the workpiece and the surface of the holding table that holds the workpiece, and the difference in height is obtained. A contact-type measuring method for obtaining the thickness of the workpiece from the difference value is known. In addition, the surface of the workpiece and the surface of the holding table that holds the workpiece are irradiated with laser light of a predetermined frequency, and the thickness of the workpiece is obtained from the difference in arrival time of the reflected waves. Measurement methods are also used. In any case, the thickness of the workpiece is also obtained from the difference between the height of the surface of the workpiece and the height of the surface of the holding table (see, for example, Patent Documents 1 and 2).

  The workpiece is a composite material containing various electronic components and metals, such as resin-encapsulated semiconductor packages, MEMS (Micro Electro Mechanical Systems), probe cards used for electrical testing of electronic components, etc. Even in the case where irregularities are formed on one surface, all the convex portions are aligned to the desired height by grinding the convex portions formed on the one surface, and the workpiece including the convex portions is processed. The entire object is formed to a desired thickness. Also in this case, the thickness of the workpiece is obtained from the difference in height between the top of the convex portion and the surface of the holding table by either a contact method or a non-contact method.

JP 2001-351890 A Japanese Patent Laid-Open No. 2001-9716

  However, it is difficult to accurately measure the thickness of the workpiece including the height of the convex portion of the workpiece having the minute convex portion. Specifically, in the case of using a contact-type thickness measuring device, if the convex portion is minute, there is a problem that considerable accuracy is required to position the contactor on the convex portion. In the case where the convex portions are densely packed, if there is an error in the positioning of the contact, there is a problem that the contact may come into contact with the plurality of convex portions at the same time. Moreover, when a contactor contacts weak parts, such as a hollow part currently formed in MEMS, there also exists a problem that the part will be damaged. On the other hand, even when using a non-contact type thickness measuring device, if the convex portions are minute or dense, there is a problem similar to the case of the contact type thickness measuring device regarding the positioning of the irradiation position, If there is an error in positioning, the reflected wave cannot be reflected to a desired position, and thickness measurement may be impossible.

  Therefore, the problem to be solved by the present invention is to accurately measure the thickness of the workpiece on the surface of the workpiece on which the projections and depressions are formed to obtain the desired thickness. It is to be able to form.

  The present invention relates to a grinding method in which the back surface of a workpiece having irregularities formed on the surface is attached to a holding member, the holding member side is held in a rotatable chuck table, and the surface of the workpiece is ground by a grinding tool. A work piece having an outer diameter smaller than that of the chuck table is attached to a holding member that covers the entire surface of the chuck table, and a measurement piece is attached to the holding member adjacent to the work piece. Grinding process of holding the holding member and rotating the chuck table to grind the measuring piece together with the convex part on the surface of the workpiece with a grinding tool, and the thickness of the measuring piece with the rotation of the chuck table temporarily stopped In the grinding process, grinding with a grinding tool is performed until the workpiece has a desired thickness based on the measurement value in the thickness measurement process. It is obtained by the.

  In the present invention, in addition to the work piece, the measurement piece is also attached to the holding member, and the thickness of the work piece is indirectly measured by measuring the thickness of the measurement piece by grinding the work piece and the measurement piece. Since the convex part is formed to measure, even if the workpiece is difficult to measure with high accuracy if the thickness is directly measured, accurate thickness measurement is possible and finished to the desired thickness. Can do.

  The workpiece 1 shown in FIGS. 1 and 2 has a plurality of convex portions 100 formed on the front surface 10, and the back surface 11 is attached to the adhesive surface 20 of the holding tape 2, which is an elastic holding member. . A metal holding frame 3 formed in a ring shape is attached to the outer peripheral portion of the adhesive surface 20 of the holding tape 2, and the workpiece 1 is supported integrally with the holding frame 3 via the holding tape 2. It will be in the state.

  A measurement piece 4 useful for measuring the thickness of the workpiece 1 is attached to the adhesive surface 20 of the holding tape 2 adjacent to the workpiece 1. The measurement piece 4 is large enough for the contact of the contact-type thickness measuring instrument to come into contact with the contact piece, so that the contact can be reliably contacted even if there is some deviation in the positioning of the contact. It is desirable to be formed. Further, as shown in FIG. 2, the measurement piece 4 has a thickness equal to or greater than the thickness of the workpiece 1 including the convex portion 100. The measurement piece 4 is formed of a material such as a silicon piece that does not deform even when contacted with the contact and can be ground with a grindstone.

  As shown in FIG. 3, the workpiece 1 supported by the holding frame 3 via the holding tape 2 is sucked and held by the holding surface 50 of the chuck table 5 provided in the grinding apparatus. On the holding surface 50, the workpiece 1 and the measurement piece 4 are held by sucking the holding tape 2. At this time, the workpiece 1 has a smaller outer diameter than the chuck table 5, and the holding tape 2 covers the entire surface of the chuck table 5. On the other hand, the holding frame 3 is fixed by a fixing portion 51 disposed on the outer peripheral side of the chuck table 5. The fixing portion 51 in the illustrated example is a magnet type, but is not limited thereto.

  When grinding the convex portion 100 of the workpiece 1 held on the chuck table 5, a grindstone 60 as a grinding tool is positioned above the workpiece 1 and the measurement piece 4. The grindstone 60 is fixed to the lower surface of the grinding wheel 62 fixed to the rotating shaft 61, and is configured to be rotationally driven by a motor 63 connected to the rotating shaft 61.

  At the time of grinding, the chuck table 5 is driven to rotate, and the convex stone 100 is ground by the rotating grindstone 60 positioned so as to pass through the center of rotation of the workpiece 1 contacting the convex part 100. The grindstone 60 also grinds the measurement piece 4 together with the convex portion 100 (grinding process).

  During grinding, the rotational drive of the chuck table 5 is temporarily stopped at an arbitrary timing, the measurement piece 4 is positioned at a position off the lower side of the grindstone 60, and the thickness of the measurement piece 4 is measured. When measuring the thickness of the measurement piece 4, as shown in FIG. 4, the contact 7 of the thickness measuring instrument is brought into contact with the surface 40 to be ground of the measurement piece 4, and the height of the contact 4 at that time is measured. Recognize Before that, the contact 7 is brought into contact with the holding surface 50 of the chuck table 5 in advance, and the height of the contact 7 at that time is recognized. Then, the difference between the height when the contact 7 comes into contact with the holding surface 50 of the chuck table 5 and the height when the contact 7 comes into contact with the measurement piece 4 is obtained, and the thickness of the holding tape 2 is further subtracted from the difference value. The value is the thickness of the measurement piece 4. Since the measurement piece 4 is ground together with the convex portion 100 of the workpiece 1, the thickness of the measurement piece 4 is also the thickness of the workpiece 1. Thus, the thickness of the workpiece 1 is obtained (thickness measurement step). As described above, since the thickness can be indirectly obtained without directly measuring the thickness of the workpiece 1, even when the convex portions 100 are minute or dense, the thickness is affected. The thickness can be measured accurately without any strict positioning accuracy being required. Moreover, since a contact does not contact the workpiece 1, even if it is a workpiece which may be damaged if a contact contacts, thickness can be measured, without damaging.

  When the obtained thickness of the workpiece 1 is thicker than a desired thickness, a grinding process is performed based on the measured value, and the thickness of the workpiece 1 is measured by the thickness measurement process. Thus, the grinding process and the thickness measurement process are repeated, and when the workpiece 1 has a desired thickness, the grinding is finished.

It is a top view which shows the state which stuck the to-be-processed object and measurement piece with the unevenness | corrugation on the surface to the holding tape, and was supported by the holding frame. It is sectional drawing which shows schematically the state which affixed the to-be-processed object and the measurement piece on the holding tape, and was supported by the holding frame. It is sectional drawing which shows schematically the state which grinds the to-be-processed object and a measurement piece in a grinding process. It is sectional drawing which shows schematically the state which made the contactor contact the measurement small piece in the thickness measurement process.

Explanation of symbols

1: Workpiece 10: Front surface 100: Convex portion 11: Back surface 2: Holding tape 20: Adhesive surface 3: Holding frame 4: Measurement piece 40: Surface to be ground 5: Chuck table 50: Holding surface 51: Fixed portion 60: Grinding wheel 61: Rotating shaft 62: Grinding wheel 63: Motor 7: Contact

Claims (1)

In the grinding method of sticking the back surface of the workpiece with irregularities formed on the surface to the holding member, holding the holding member side in a rotatable chuck table, and grinding the surface of the workpiece with a grinding tool,
A workpiece having an outer diameter smaller than that of the chuck table is attached to a holding member that covers the entire surface of the chuck table, and a measurement piece is attached to the holding member adjacent to the workpiece. A grinding step of holding the holding member and rotating the chuck table to grind the measurement piece together with a convex portion on the surface of the workpiece with a grinding tool;
A thickness measuring step of measuring the thickness of the measurement piece in a state in which the rotational driving of the chuck table is temporarily stopped,
A grinding method in which, in the grinding step, grinding with the grinding tool is performed until the workpiece has a desired thickness based on the measurement value in the thickness measurement step.

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