JP2009182060A - Cutting-working method for plate-form material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting-working method for plate-form materials which so controls the cutting depth of a cutting byte in a wafer accurately without requiring any reference height-position indexing frequently as to be able to cut a plate-form material to its desired thickness. <P>SOLUTION: The cutting-working method for plate-form materials has a first cutting process for so setting a desired cutting thickness d1 of a plate-form material 23 and so holding it on a chuck table 34 as to cut it, a second calculating process of the thickness of a plate-form material for so measuring the top-surface height of the plate-form material as to calculate a thickness d2 of the plate-form material obtained after the first cutting process based on the measured value and the top-surface height of the chuck table, a correction-value calculating process for so calculating the difference between the desired cutting thickness d1 set in the first cutting process and the thickness of the plate-form material which is calculated in the second calculating process of a plate-form material as to obtain a cutting correction value, and a second cutting process for so setting a desired finishing thickness d in consideration of the cutting correction value calculated in the correction-value calculating process as to cut the plate-from material to the desired finishing thickness. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a cutting method for cutting a laminated portion of a semiconductor wafer having a laminated portion made of resin, metal, or the like on a surface thereof to a desired thickness.

  There are various techniques for realizing light and thin semiconductor devices. As an example, a plurality of metal protrusions called bumps having a height of about 10 to 100 μm are formed on the surface of a device formed on a semiconductor wafer, and these bumps are directly bonded to the electrodes formed on the wiring board. A technique called flip chip bonding has been put into practical use.

  The bump formed on the device surface of the semiconductor wafer is formed by a method such as plating or stud bump. For this reason, the heights of the individual bumps are non-uniform, and it is difficult to uniformly bond the plurality of bumps to the electrodes of the wiring board as they are.

  Therefore, as a method of cutting the bumps to a desired thickness, a method of scraping with a cutting bit has been proposed in, for example, Japanese Patent Application Laid-Open No. 2000-173954. Since the height of a general bump is as small as about 10 to 100 μm, such cutting requires control in the micron order.

Generally, in an apparatus as described in the above-mentioned publication, the cutting amount is controlled by the distance from the chuck table that holds the workpiece. That is, the cutting tool and the chuck table are brought into electrical contact to establish electrical continuity, and the Z-axis direction position (height position) at that time is stored to determine the reference position (origin position) in the Z-axis direction. The workpiece is cut by setting the remaining cutting amount (distance from the chuck table) of the workpiece.
Japanese Patent Application Laid-Open No. 2000-173954

  However, when the cutting tool is diamond or CBN (cubic boron nitride), electrical conduction cannot be obtained only by contacting the cutting tool with the chuck table. Therefore, it is necessary to set a reference position by placing a contact sensor having a predetermined thickness on the chuck table and bringing the contact sensor into contact with the cutting tool.

  On the other hand, with the operation of the apparatus, heat is generated at the electrical parts and processing points, and this heat propagates into the apparatus, thereby causing thermal expansion of the cutting tool support part and the chuck table support part. Further, since the cutting tool tip is worn or deformed by continuous processing, the positional relationship between the cutting tool and the chuck table is displaced with the processing. Therefore, in order to control the cutting amount on the micron order, it is necessary to frequently perform the reference position in the Z-axis direction, and the work becomes complicated.

  Furthermore, when the cutting tool is composed of diamond or CBN, it is necessary to install a contact sensor on the chuck table in order to determine the reference position, so that it is difficult to process the workpiece continuously. The workability is bad.

  The present invention has been made in view of these points, and the object of the present invention is to provide a highly accurate cutting amount of a cutting tool into a plate-like object without frequently performing a reference position in the Z-axis direction. It is to provide a method for cutting a plate-like material that can be controlled to a desired thickness.

  According to the present invention, a plate shape is formed by grinding the upper surface of a plate-like object composed of a substrate portion and a laminated portion formed with a predetermined thickness on the upper surface of the substrate portion, and forming the laminated portion with a predetermined thickness. A method of cutting an object, wherein the height measurement means measures the upper surface height of the plate-like object held on the chuck table, and measures the upper surface height of the chuck table to determine the thickness of the plate-like object. A target of the plate-like object held on the chuck table based on the first plate-like object thickness calculating step to be calculated and the thickness of the plate-like object calculated in the first plate-like object thickness calculating step A first cutting step of setting a cutting thickness and cutting the upper surface of the plate-like object so that the plate-like object has a target cutting thickness; and the first cutting unit held on the chuck table by the height measuring means The height of the upper surface of the plate-like object after the cutting process is measured, and the measured value and the first plate-like object thickness calculator And the target cutting set in the first cutting step, the second plate thickness calculating step for calculating the thickness of the plate after the first cutting step, and the height of the upper surface of the chuck table measured in step (1). Calculating a difference between the thickness and the thickness of the plate-like object calculated in the second plate-like object thickness calculating step to obtain a cutting correction value; and the cutting calculated in the correction value calculating step A target finish thickness setting step for setting a target finish thickness of the plate-like object taking the correction value into consideration; and a second cutting step for cutting the plate-like object to the target finish thickness set in the target finish thickness setting step. There is provided a cutting method of a plate-like object characterized by the above.

  In the first cutting step, instead of cutting the entire upper surface of the plate-like object, only a part thereof may be cut.

  According to the present invention, since the position of the Z-axis direction (height direction) is corrected for each plate-like object, there is no need to frequently perform the reference positioning in the Z-axis direction, and the plate-like object can be obtained with high accuracy. It becomes possible to cut to thickness. In addition, the through-butt can be improved by cutting only a part of the upper surface of the plate-like object in the first cutting step.

  Hereinafter, the cutting method of the embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a perspective view of a cutting apparatus suitable for carrying out the cutting method of the embodiment of the present invention.

  The housing 4 of the cutting device 2 includes a horizontal housing part 6 and a vertical housing part 8. A pair of guide rails (only one is shown) 10 extending in the vertical direction are fixed to the vertical housing portion 8.

  A cutting unit 12 is mounted along the pair of guide rails 10 so as to be movable in the vertical direction. The cutting unit 12 is attached to a moving base 14 whose housing 22 moves up and down along the pair of guide rails 10.

  The cutting unit 12 includes a housing 22, a spindle (not shown) rotatably accommodated in the housing 22, a servo motor 24 that rotationally drives the spindle, a bite wheel 26 fixed to the tip of the spindle, and a bite wheel 26. A cutting tool (cutting blade) 28 is detachably attached to the tool.

  The cutting unit 12 includes a cutting unit moving mechanism 20 including a ball screw 16 and a pulse motor 18 that move the cutting unit 12 in the vertical direction along the pair of guide rails 10. When the pulse motor 18 is pulse-driven, the ball screw 16 rotates and the moving base 14 is moved in the vertical direction.

  A chuck table unit 30 is disposed in the horizontal housing portion 6. The chuck table unit 30 includes a chuck table base 32 and a chuck table 34 mounted on the chuck table base 32. The chuck table 34 is moved in the Y-axis direction by a chuck table moving mechanism (Y-axis direction feed mechanism) (not shown).

  Reference numeral 36 denotes a height measuring device assembly for measuring the height of the chuck table 34, the height of the wafer 11 (see FIG. 2) held on the chuck table 34, and the like, and a gate shape fixed to the horizontal housing portion 6 of the housing 4. The support member 38 is included. The support member 38 is attached with a pair of linear gauges 40 and 42 that measure the height in a contact manner.

  A rectangular attachment member 44 is further fixed to the support member 38. The mounting member 44 is provided with an X-axis drive mechanism including a ball screw 48 and a pulse motor 50. When the pulse motor 50 is driven in pulses, the slider 46 is moved in the X-axis direction.

  The slider 46 is equipped with a Z-axis drive mechanism including a ball screw 54 and a pulse motor 56. When the pulse motor 56 is driven in a pulsed manner, the non-contact type height measuring device 52 is moved in the vertical direction (Z-axis direction). Moved.

  The non-contact type height measuring device 52 includes, for example, a non-contact type height measuring unit 58 such as a scanning white interferometer SWLI (manufactured by Toray Engineering Co., Ltd.) and an alignment unit 60 having an imaging unit such as a CCD camera. It is attached. Instead of the scanning white interferometer, ultrasonic measurement means, laser beam measurement means, or the like may be employed as non-contact type height measurement means.

  The horizontal housing portion 6 of the housing 4 includes a first wafer cassette 62, a second wafer cassette 64, a wafer transport mechanism 66, a positioning table 68 having a plurality of positioning pins 70, a wafer carry-in mechanism 72, A wafer carry-out mechanism 74 and a spinner unit 76 are provided.

  Further, a cleaning water spray nozzle 78 for cleaning the chuck table 34 is provided at a substantially central portion of the horizontal housing portion 6. The cleaning water jet nozzle 78 ejects cleaning water toward the chuck table 34 in a state where the chuck table 34 is positioned in the wafer carry-in / out area.

  Referring to FIG. 2, a plan view of the semiconductor wafer 11 is shown. The semiconductor wafer 11 is made of, for example, a silicon wafer having a thickness of 600 μm, and a plurality of streets 13 are formed in a lattice shape on the surface 11a, and an IC is formed in each of a plurality of regions partitioned by the plurality of streets 13. A device 15 such as an LSI is formed.

  The semiconductor wafer 11 configured as described above includes a device region 17 in which the device 15 is formed, and an outer peripheral surplus region 19 that surrounds the device region 17. A notch 21 is formed on the outer periphery of the semiconductor wafer 11 as a mark indicating the crystal orientation of the silicon wafer.

  FIG. 3 is a cross-sectional view of the device 15 portion of the semiconductor wafer 11. A device 15 is formed on a silicon substrate 23 by a well-known semiconductor manufacturing process, and a laminated portion 25 including a plurality of bumps 27 and a resin layer 29 is formed on the device 15. The bumps 27 are made of a metal such as copper, for example, and are connected to the electrodes of the device 15.

  The cutting operation of the cutting apparatus 2 configured as described above will be described below. The semiconductor wafer 11 accommodated in the first wafer cassette 62 is conveyed by the vertical movement and forward / backward movement of the wafer conveyance mechanism 66 and placed on the wafer positioning table 68.

  After the wafer placed on the wafer positioning table 68 is centered by a plurality of positioning pins 70, the wafer loading mechanism 72 pivots to the chuck table 34 positioned in the wafer loading / unloading area. It is placed and sucked and held by the chuck table 34.

  When the chuck table 34 sucks and holds the wafer 11 as described above, the chuck table moving mechanism is operated to position the chuck table 34 at the height measurement position shown in FIG.

  At the height measurement position, the height of the upper surface of the chuck table 34 is measured with the first linear gauge 40, and the height of the wafer 11 is measured by bringing the second linear gauge 42 into contact with the stacked portion 25 of the semiconductor wafer 11. To do. The thickness of the wafer 11 is calculated from the difference between the readings of the two linear gauges 40 and 42.

  Next, based on the thickness of the wafer 11 calculated from the thickness calculation step described above, a first cutting step of flattening the upper surface of the wafer 11 held by the chuck table 34 with the cutting unit 12 is performed.

  In the first cutting step, the target cutting height of the wafer 11 held on the chuck table 34 based on the thickness of the wafer 11 calculated from the thickness calculating step, that is, the upper surface of the chuck table 34 as shown in FIG. The height d1 from is set.

  Then, as shown in FIG. 5, the first cutting process is performed by feeding the chuck table 34 in the arrow Y direction at, for example, 0.66 mm / sec while rotating the cutting tool 28 in the arrow A direction to, for example, 2000 rpm. In the first cutting step, only a part of the laminated portion 25 may be cut.

  After performing the first cutting step, the chuck table moving mechanism is operated to reposition the chuck table 34 at the height measurement position shown in FIG. In the first embodiment, the height of the wafer 11 is measured by bringing the second linear gauge 42 into contact with the laminated portion 25 cut in the first cutting step. The actual thickness d2 of the wafer 11 after the first cutting step is calculated from the difference between the detected height of the wafer 11 and the height of the upper surface of the chuck table 34 detected in FIG.

  In the second embodiment, after the first cutting process is performed, the chuck table moving mechanism is actuated to return the chuck table 34 to the height measurement position again, and the alignment and non-contact height by the non-contact height measuring device 52 are achieved. Perform the measurement process.

  In the alignment process, the imaging unit of the alignment unit 60 images the alignment target stacked portion 25, and moves the non-contact type height measuring unit 58 to the detected position as shown in FIG.

  At the position moved in the alignment step, the height of the wafer 11 is measured by the non-contact type height measuring means 58. The actual thickness d2 of the wafer 11 after the first cutting step is calculated from the difference between the detected height of the wafer 11 and the height of the upper surface of the chuck table 34 detected in FIG. In the second embodiment, the alignment step may be performed before the first cutting step.

  Next, a cutting correction amount is calculated from the difference between the actual thickness d2 of the wafer 11 after the first cutting step and the target thickness d1. This cutting correction amount is stored in the memory of the controller of the cutting device 2. Alternatively, the operator records the cutting correction amount as a memo.

  Next, the target finish thickness of the wafer 11 taking into account the cutting correction amount is set, the pulse motor 24 is driven by a predetermined pulse by the controller of the cutting device 2, and the cutting tool 28 corresponds to the target finish thickness as shown in FIG. Lower by distance.

  Then, as in the first cutting step, the second cutting step is performed while the cutting tool 28 is rotated in the direction of arrow A at 2000 rpm and the chuck table 34 is fed in the direction of arrow Y at, for example, 0.66 mm / second. Thereby, the wafer 11 can be finished to a desired thickness d.

  After carrying out the second cutting step, a chuck table moving mechanism (not shown) is driven to position the chuck table 34 in the wafer loading / unloading area on the front side of the apparatus. After the suction and holding of the wafer 11 held on the chuck table 34 is released, the wafer 11 is conveyed to the spinner unit 76 by the wafer carry-out mechanism 74.

  The wafer conveyed to the spinner unit 76 is cleaned here and spin-dried. Next, the wafer 11 is stored in a predetermined position of the second wafer cassette 64 by the wafer transport mechanism 66.

  As a modification of the above-described embodiment, the linear gauges 40 and 42 which are contact-type height measuring means are omitted, and the non-contact-type height measuring means 58 is also used as the function of the linear gauges 40 and 42. good.

  According to the above-described embodiment, since correction is performed after the first cutting process for each semiconductor wafer 11, it is not necessary to frequently perform the reference positioning in the Z-axis direction, and the semiconductor wafer 11 can be uniformly distributed to a desired thickness with high accuracy. Can be cut. Further, by cutting only a part of the laminated portion 25 of the semiconductor wafer 11 in the first cutting process, it is possible to improve the through-butt.

It is an external appearance perspective view of a cutting device. It is a top view of a semiconductor wafer. It is sectional drawing of a semiconductor wafer. It is explanatory drawing of a wafer thickness calculation process. It is explanatory drawing of a laminated part planarization process (1st cutting process). It is explanatory drawing of a correction value calculation process. It is explanatory drawing of a laminated part thickness calculation process. It is explanatory drawing of a 2nd cutting process.

Explanation of symbols

2 Cutting device 11 Semiconductor wafer 12 Cutting unit 15 Device 17 Device region 19 Peripheral surplus region 23 Substrate 25 Laminating portion 27 Bump 28 Cutting tool 29 Resin layer 34 Chuck table 36 Height measuring device assembly 40, 42 Linear gauge 58 Non-contact Type height measuring means 60 alignment means

Claims (2)

A cutting method for a plate-like material, in which the upper surface of a plate-like material composed of a substrate portion and a laminated portion formed with a predetermined thickness on the upper surface of the substrate portion is ground, and the laminated portion is formed to a predetermined thickness. Because
First plate thickness for measuring the upper surface height of the plate-like object held on the chuck table by the height measuring means and calculating the thickness of the plate-like object by measuring the upper surface height of the chuck table A calculation process;
Based on the thickness of the plate-like object calculated in the first plate-like object thickness calculating step, a target cutting thickness of the plate-like object held on the chuck table is set, and the plate-like object is set as a target. A first cutting step of cutting the upper surface of the plate-like object so as to have a cutting thickness;
The height of the upper surface of the plate-like object after the first cutting step held on the chuck table by the height measuring means is measured, and the measured value and the chuck measured in the first plate-like object thickness calculating step From the height of the table upper surface, a second plate thickness calculation step for calculating the thickness of the plate after the first cutting step,
A correction value calculating step for calculating a cutting correction value by calculating a difference between the target cutting thickness set in the first cutting step and the thickness of the plate-like material calculated in the second plate-like material thickness calculating step. When,
A target finish thickness setting step of setting a target finish thickness of the plate-like object taking into account the cutting correction value calculated in the correction value calculation step;
A second cutting step of cutting the plate-like object to the target finish thickness set in the target finish thickness setting step;
A cutting method for a plate-like object comprising:   The plate cutting method according to claim 1, wherein only a part of the upper surface of the plate is cut in the first cutting step.

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