JP2012152858A - Grinding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform accurate grinding so that a prescribed member embedded into the other member may be applied with cueing.SOLUTION: The grinding device comprises a holding means in which a holding face for holding a workpiece is formed, a processing means which grinds the workpiece held by the holding means, and a control means which controls the movement of the processing means. The workpiece is constituted of a first member whose reflectance is first reflectance, and a second member which covers the first member and whose reflectance is second reflectance, the control means has a detection part which irradiates detection light to a face to be ground of the workpiece, and receives reflection light from the face to be ground, and when it is decided that the first member covered by the second member is exposed on the basis of a light receiving amount detected by the detection part, the grinding of the workpiece is stopped.

Description

  The present invention relates to a grinding apparatus for grinding a workpiece such as a semiconductor wafer.

  In the manufacturing process of a semiconductor device, in order to obtain a target thickness of the semiconductor device, the back surface thereof is ground and polished at the stage of a work which is an aggregate of a large number of semiconductor devices, and thinned. In addition, with recent remarkable thinning of semiconductor devices, workpieces are processed to be thinner.

  In general, grinding or polishing of a workpiece is performed while measuring its thickness. The applicant of the present invention has proposed a grinding apparatus that accurately measures the thickness of a workpiece while bringing the measuring probe into contact with the surface to be processed and grinds the workpiece to a desired thickness (see Patent Document 1).

JP 2000-6018 A

  However, according to the above grinding apparatus, for example, when cueing a predetermined member such as cueing a Cu post embedded in resin by grinding the resin, the member is embedded. Since the height is not always constant, cueing of the member may not be performed properly even if the workpiece is ground to a constant thickness.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a grinding apparatus capable of cueing a predetermined member with high accuracy.

  In order to solve the above-described problems and achieve the object, a grinding apparatus according to the present invention includes a holding unit having a holding surface for holding a workpiece, and a processing unit for grinding the workpiece held by the holding unit. A grinding device having a control means for controlling the movement of the processing means, wherein the workpiece has a first member whose reflectance is a first reflectance and a reflectance covering the first member. Consists of a second member having a second reflectivity, and the control means has a detection unit for irradiating the surface to be ground of the workpiece being ground with detection light and receiving the reflected light from the surface to be ground. The grinding of the workpiece is stopped when it is determined that the first member covered by the second member is exposed based on the amount of received light detected by the detection unit.

  According to the grinding device of the present invention, it is possible to cue a predetermined member with high accuracy.

FIG. 1 is a perspective view showing a configuration of a grinding apparatus according to an embodiment of the present invention. FIG. 2 is a side view showing a configuration of a grinding apparatus according to an embodiment of the present invention. FIG. 3 is a schematic diagram illustrating a configuration of a detection unit of a grinding apparatus according to an embodiment of the present invention. FIG. 4 is a schematic diagram showing a configuration of a workpiece W that is an embodiment of the present invention. FIG. 5 is a flowchart showing the flow of detection processing according to an embodiment of the present invention. FIG. 6 is a diagram for explaining detection processing according to an embodiment of the present invention. FIG. 7 is a diagram for explaining detection processing according to an embodiment of the present invention. FIG. 8 is a diagram for explaining detection processing according to an embodiment of the present invention. FIG. 9 is a schematic diagram showing a configuration of a modified example of the workpiece W according to the embodiment of the present invention.

  Hereinafter, the configuration and operation of a grinding apparatus according to an embodiment of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

[Configuration of grinding equipment]
First, with reference to FIGS. 1-3, the structure of the grinding device which is one Embodiment of this invention is demonstrated. FIG. 1 is a perspective view illustrating a configuration of a grinding apparatus according to an embodiment of the present invention, and FIG. 2 is a side view illustrating a configuration of a grinding apparatus according to an embodiment of the present invention. FIG. 3 is a schematic diagram illustrating a configuration of a detection unit of a grinding apparatus according to an embodiment of the present invention.

  As shown in FIG. 1, a grinding apparatus 1 according to an embodiment of the present invention includes a rectangular parallelepiped base 2. On the front side of the upper surface of the base 2, an operation panel 3 that receives various instructions for the grinding device 1 is provided. A table support 4 for supporting the chuck table 41 is provided on the rear side of the operation panel 3. A column portion 5 is provided on the rear side of the table support 4. A grinding unit 6 is supported on the front surface of the support column 5 so as to be movable in the vertical direction. In the vicinity of the grinding unit 6, a detection unit 70 that detects a member constituting the workpiece W held on the chuck table 41 is provided. A control unit (control means) C controls and supervises these components.

  The workpiece W is composed of two types of members disposed on the substrate, and is configured such that the first member is embedded in the second member. Although it does not specifically limit as a member which comprises the workpiece | work W, For example, Cu can be illustrated as a 1st member and mold resin etc. can be illustrated as a 2nd member. The substrate is not particularly limited, and examples thereof include semiconductor wafers such as silicon wafers, gallium arsenide wafers, and silicon carbide wafers, inorganic material substrates such as ceramic substrates, glass substrates, and sapphire substrates.

  The table support 4 is provided in a square shape and rotatably supports the chuck table 41. The table support 4 is connected to a drive mechanism (not shown), and is slid in the front-rear direction within the opening 2 a formed on the upper surface of the base 2 by a drive force supplied from the drive mechanism. As a result, the chuck table 41 is separated from the grinding position where the exposed surface of the workpiece W is opposed to the grinding unit 6 and forwardly from the grinding position, and the workpiece W before processing is supplied, while the workpiece W after processing is supplied. Is slid to and from the repositioning position at which it is collected. Before and after the table support 4, a dust-proof cover 8 is provided that suppresses grinding wheel waste generated during grinding of the workpiece W from entering the base 2. The dust cover 8 is attached to the front and rear surfaces of the table support 4, and is provided so as to be expandable / contractable according to the movement position of the table support 4, and is configured to cover the opening 2 a of the base 2.

  The chuck table 41 constitutes a holding means according to the present invention, and is formed in a disk shape. A holding surface 41a for holding a workpiece W carried in the direction indicated by an arrow A in the figure is formed on the upper surface thereof. Has been. An adsorption surface is formed of a porous ceramic material at the central portion of the holding surface 41a. The chuck table 41 is connected to a suction source (not shown) arranged in the base 2 and sucks and holds the workpiece W on the suction surface of the holding surface 41a. Further, the chuck table 41 is connected to a rotation drive mechanism (not shown), and is rotated while the workpiece W is held on the holding surface 41a by the rotation drive mechanism.

  The support column 5 is provided in a rectangular parallelepiped shape, and a grinding unit moving mechanism 51 for moving the grinding unit 6 above the chuck table 41 is provided on the front surface thereof. The grinding unit moving mechanism 51 has a Z-axis table 52 that moves in the vertical direction with respect to the support column 5 by a ball screw type moving mechanism. The grinding unit 6 is supported on the Z-axis table 52 via a support portion 53 attached to the front side thereof.

  The grinding unit 6 constitutes processing means according to the present invention, and has a grinding wheel 61 that is detachably attached to a lower end of a spindle (not shown). The grinding wheel 61 is composed of, for example, a diamond grinding stone in which diamond abrasive grains are hardened with a binder such as metal bond or resin bond. The grinding unit 6 is exposed to the surface of the workpiece W by rotating the grinding wheel 61 in the same direction as the rotation direction of the chuck table 41 and bringing the grinding wheel 61 into contact with the surface of the workpiece W arranged at the grinding position. The processed member is ground.

  The detection unit 70 includes an inverted L-shaped arm portion 71 erected on the side of the opening 2 a of the base 2, and a laser head portion 72 provided at the tip of the arm portion 71. As shown in FIG. 2, the detection unit 70 irradiates the surface of the work W with laser light from the laser head unit 72 and receives the laser light reflected on the surface of the work W.

  As shown in FIG. 3, the laser head unit 72 includes a case 721, a separation wall 722, an irradiation system 723 including a light source and a lens, and a sensor 724 connected to the control unit C. Irradiating system 723 while supplying water supplied from a water supply port 725 provided on the side surface of the case 721 to the surface of the workpiece W from a drainage port 726 provided on the lower surface of the case 721 in a space surrounded by 722. Irradiates the surface of the workpiece W with laser light and receives reflected light with the sensor 724. And the control part C detects the member exposed to the workpiece | work W surface based on the change of the received light quantity of reflected light.

  The control unit C that comprehensively controls the operation of each component of the grinding device 1 configured as described above is configured by a microcomputer or the like with a built-in memory that holds various data necessary for the operation of the grinding device 1. The Under the control of the control unit C, the grinding device 1 executes a detection process described below.

[Detection processing]
As shown in FIG. 3, the laser head unit 72 of the detection unit 70 irradiates the ground surface of the workpiece W rotating with the rotation of the chuck table 41 with laser light as detection light and applies reflected light. Receive light. Such processing is performed by appropriately changing the distance from the rotation axis L of the workpiece W (chuck table 41) according to the configuration of the workpiece W and determining the detection path.

  Here, a detection processing procedure according to the present embodiment will be described with reference to FIGS. FIG. 4 is a schematic view illustrating a workpiece W as a detection target of the present embodiment, and FIG. 5 is a flowchart showing a detection processing procedure.

  As shown in FIG. 4, the workpiece W includes two types of members disposed on the substrate, and is configured such that the first member is embedded in the second member. For example, a Cu chip as a first member is disposed on a substrate and covered with a mold resin as a second member.

  When the second member of the workpiece W is ground and the first member is cued, the detection process according to the present embodiment is performed. For example, when the detection process is performed along the path indicated by the arrow B in FIG. 4 while rotating the workpiece W (chuck table 41), the detection unit 70 periodically reflects the reflected light from the first member and the second member. The reflected light is received. Here, since the reflectance of the first member is different from the reflectance of the second member, the intensity of the reflected light changes periodically.

  On the other hand, if the grinding of the second member is inadequate and the first member has not been cueed, or if the cueing of the first member is inadequate, the detection process may be performed along the same path. The intensity of reflected light does not change. Therefore, it can be determined that the first member has been sufficiently cueed because the intensity of the reflected light has changed.

  The flowchart shown in FIG. 5 starts at the timing when the operator operates the operation panel 3 to instruct the execution of the detection process, and the detection process proceeds to step S1.

  In the process of step S1, the control unit C controls the operation of the detection unit 70 to irradiate the workpiece W rotating with the rotation of the chuck table 41 with the laser beam and to receive the reflected light. Store the amount in memory. Thereby, the process of step S1 is completed and a detection process progresses to the process of step S2.

  In step S2, the control unit C confirms the amount of received light stored in step S1 and determines whether there is a change. If not changed (Step S2, No), it is determined that the first member is not sufficiently positioned (Step S3), the grinding of the workpiece W is continued (Step S4), and the process returns to Step S1. On the other hand, if there is a change (step S2, Yes), it is determined that the cueing of the first member has been completed (step S5), and the grinding unit 6 is controlled to stop grinding the workpiece W ( Step S6), a series of detection processing is terminated.

  Here, a specific method for determining whether there is a change in the amount of received light will be described with reference to FIGS. 6 to 8 illustrate the result of measuring the intensity data of the received reflected light and calculating the moving average value of the data along the path indicated by the arrow B in FIG. 4 for the workpiece W in FIG. FIG. 6 is for a workpiece W in which the second member is not sufficiently ground and the first member is not cued, and FIG. 7 is the first member in which the second member is not sufficiently ground. FIG. 8 is for a workpiece W in which the second member is ground and the first member is sufficiently cueed.

  For example, for the workpiece W in FIG. 4, it is determined that the change in the amount of received light in step S <b> 2 described above has occurred because the moving average value of the intensity data of the reflected light has exceeded a predetermined threshold value. It can be judged that the cue has been sufficiently made. About a threshold value, it sets based on the reflectance of a 1st member and a 2nd member previously. Then, in FIG. 6 and FIG. 7, since the moving average value is below the threshold value, grinding is continued. In FIG. 8, since the moving average value exceeds the threshold value, grinding is stopped.

  The grinding process according to the present embodiment can also be applied to a workpiece W in which a plate made of a first member is embedded in a second member as shown in FIG. For such a workpiece W, when the first member is cueed, the amount of received light detected along the path indicated by the arrow C in FIG. Therefore, in step S2, when the intensity data of the reflected light changes in excess of a threshold set in advance based on the reflectance of the first member and the second member, the amount of reflected light received is changed. It is determined that one member has been cueed.

  As is clear from the above description, according to the detection process according to an embodiment of the present invention, the detection unit 70 is embedded in the second member due to the difference in reflectance between the first member and the second member. Further, since the cue of the first member can be detected, cueing of the predetermined member can be performed with high accuracy.

DESCRIPTION OF SYMBOLS 1 Grinding device 6 Grinding unit 41 Chuck table 70 Detection part W Work C Control part

Claims (1)

A grinding apparatus having a holding means formed with a holding surface for holding a work, a processing means for grinding the work held by the holding means, and a control means for controlling the movement of the processing means,
The workpiece is composed of a first member whose reflectivity is the first reflectivity and a second member whose reflectivity covering the first member is the second reflectivity,
The control means has a detection unit that irradiates the surface to be ground of the workpiece being ground with detection light and receives reflected light from the surface to be ground, and based on the amount of received light detected by the detection unit A grinding apparatus characterized by stopping grinding of the workpiece when it is determined that the first member covered by the second member is exposed.

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