JP2019038061A - Grinder, and grinding method - Google Patents

Abstract

To provide a grinder and a grinding method by which a device layer is accurately ground.SOLUTION: Thickness measurement means 100 of a grinder comprises: a projector which projects measurement light having transmissivity with respect to a silicon carrier 230 of a plate-like work-piece W and an adhesive layer 220 from the silicon carrier side, and a light receiver 105 which receives first reflectance 122 of the measurement light reflected on a surface of the silicon carrier, second reflectance 123 reflected on a boundary surface between the silicon carrier and the adhesive layer, and third reflectance 124 transmitted through the silicon carrier and is reflected on a boundary surface between the adhesive layer and a device layer 210, for each wavelength; a first calculation part which calculates a thickness of the silicon carrier by a light path length difference between the first reflectance and the second reflectance which have been received by the light receiver; a second calculation part which calculates a thickness of the adhesive layer by a light path length difference between the second reflectance and the third reflectance which have been received by the light receiver; and a device layer calculation part which calculates a thickness of the device layer by subtracting a total value of the thickness of the silicon carrier and the thickness of the adhesive layer from a thickness of the work-piece.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a grinding apparatus for grinding a plate-like workpiece and a grinding method for grinding a plate-like workpiece.

  WL-CSP (Wafer-Level Chip Size Package) is a technology in which chips stacked on a wiring board in a wafer state are sealed with a mold resin to form a device layer, and then divided into device packages with a cutting blade or the like. Since the size of the package obtained by dividing the wafer into the size of the semiconductor device chip, it is widely adopted from the viewpoint of miniaturization and weight reduction.

  In the WL-CSP manufacturing process described above, silicon chips stacked on the surface of the wiring substrate and metal posts connected to the electrodes of the silicon chips are formed, and these are sealed with a mold resin to form a device layer. To do.

  Next, the mold resin forming the device layer is ground and thinned to a predetermined target thickness, and the metal post is exposed to the surface of the mold resin, and external terminals called bumps are formed on the end surface of the metal post. . Then, it cuts with a cutting device etc. and divides | segments into each CSP.

  As described above, in order to protect the semiconductor device from impact, moisture, and the like, it is useful to seal with a mold resin that serves as a sealant. Normally, the mold resin is a resin mixed with a filler made of SiC, and the thermal expansion coefficient of the mold resin is brought close to the thermal expansion coefficient of the semiconductor device chip, resulting in a package during heating caused by the difference in the thermal expansion coefficient. To prevent damage.

  On the other hand, grinding the mold resin layer of the WL-CSP wafer to reduce the thickness of the metal post to the same height and to expose the metal post on the surface of the mold resin, the diamond is solidified with glass or resin. A grinding device called a grinder having a grindstone or a cutting tool equipped with a cutting blade made of single crystal diamond is used (for example, see Patent Document 1).

JP 2013-008898 A

  A plate-like workpiece that is ground by a grinding machine that executes the manufacturing process of the WL-CSP wafer described above is formed from the lower surface from a silicon carrier, an adhesive layer, and the device layer described above. In the conventional grinding process, when starting the grinding process, the total thickness of the plate-like workpiece is measured, and the mold resin constituting the device layer is ground on the mold resin surface by grinding a predetermined amount from this total thickness. The post is exposed.

  A thickness error of about ± 20 μm is allowed for the silicon carrier constituting the plate-like workpiece, and a thickness error of about ± 10 μm is allowed for the adhesive layer. That is, in the total thickness of the plate-shaped workpiece described above, a thickness error of about ± 30 μm may occur in the silicon carrier and the adhesive layer. In the conventional grinding process, it is assumed that the variation in the total thickness of the plate-shaped workpiece before processing is caused by the above-described thickness error between the silicon carrier and the adhesive layer. Had been implemented. However, when processing is performed based on this assumption, there has been a problem that the mold resin constituting the device layer is excessively scraped or the metal post is not sufficiently exposed due to insufficient shaving.

  In order to thin the mold resin layer by grinding the upper surface of the device layer and align the height of the metal post, and to carry out the grinding process to reliably and accurately expose the metal post on the surface of the mold resin, the device layer It is necessary to accurately grind so that the thickness of the film becomes a predetermined target thickness. However, the plate-like workpiece is composed of a silicon carrier, an adhesive layer, a device layer, and a plurality of layers. Further, since the device layer is composed of a wiring substrate, a silicon chip, and a mold resin, its thickness is directly reduced. It was difficult to measure, and it was difficult to process the device layer to a predetermined target thickness.

  The present invention has been made in view of the above-mentioned facts, and its main technical problem is that a silicon carrier, an adhesive layer, and a device layer in which a silicon chip laminated on a wiring board is sealed with a mold resin from the lower surface are formed. An object of the present invention is to provide a grinding apparatus and a grinding method that can accurately grind a device layer to a target thickness when a plate-like workpiece is processed by a grinding apparatus.

  In order to solve the above-mentioned main technical problem, according to the present invention, a plate-like work formed from a device layer in which a silicon carrier, an adhesive layer, and a silicon chip laminated on a wiring substrate are sealed with a mold resin from the lower surface. A holding table having a holding surface for holding the surface, a grinding means for grinding a device layer of a plate-like workpiece held by the holding table with a grinding wheel, and a holding table height measuring gauge for measuring the upper surface height of the holding table And a difference between the plate-like workpiece height measuring gauge for measuring the upper surface height of the plate-like workpiece held by the holding table, the holding table height measuring gauge, and the plate-like workpiece height measuring gauge A workpiece thickness calculator that calculates a total thickness of the plate workpiece from the grinding table, the grinding device before the plate workpiece is held by the holding table Thickness measuring means for measuring the thickness of the silicon carrier and the adhesive layer is provided, and the thickness measuring means is permeable to the silicon carrier and the adhesive layer from the silicon carrier side of the plate-like workpiece. A light projecting unit that projects measurement light of a wavelength; a first reflected light reflected by the surface of the silicon carrier; and a second reflected light reflected by an interface between the silicon carrier and the adhesive layer. And a light receiving unit that receives, for each wavelength, a combined light composed of third reflected light that passes through the silicon carrier and is reflected at the interface between the adhesive layer and the device layer, and the light receiving unit A first calculation unit that calculates the thickness of the silicon carrier based on an optical path length difference between the first reflected light and the second reflected light, and the second reflected light received by the light receiving unit. The thickness of the adhesive layer due to the optical path length difference with the third reflected light The thickness of the device layer is calculated by subtracting the sum of the thickness of the second calculation unit for calculating the thickness of the silicon carrier and the thickness of the adhesive layer from the thickness of the plate-like workpiece calculated by the workpiece thickness calculation unit. There is provided a grinding apparatus for grinding a plate-like workpiece held by the holding table with a grinding means until the thickness calculated by the device layer calculation unit reaches a predetermined target thickness.

  In order to solve the above main technical problem, according to the present invention, a board formed from a device layer in which a silicon chip laminated on a silicon carrier, an adhesive layer, and a wiring board is sealed from a lower surface with a mold resin. A method of grinding a plate-like workpiece by holding the shaped workpiece on a holding surface of a holding table and grinding the upper surface to make the device layer have a predetermined thickness, which is permeable to the silicon carrier and the adhesive layer A first reflected light reflected from the lower surface of the silicon carrier and a second reflected light reflected from the interface between the silicon carrier and the adhesive layer; A first measurement step of measuring the thickness of the silicon carrier based on the optical path length difference, a second reflected light reflected by reflection of the measurement light, and a third reflected by the interface between the adhesive layer and the device layer of A second measuring step for measuring the thickness of the adhesive layer based on the optical path length difference from the incident light; a holding step for holding the silicon carrier side of the plate-like workpiece on the holding surface; and Work thickness for measuring the height of the upper surface of the held plate-like workpiece and the height of the holding surface, and calculating the thickness of the plate-like workpiece from the difference between the upper surface height of the plate-like workpiece and the height of the holding surface A device layer thickness calculating step for calculating the thickness of the device layer by subtracting the thickness of the silicon carrier and the thickness of the adhesive layer from the thickness of the plate-like workpiece calculated in the workpiece thickness calculating step; And a grinding step of grinding the plate workpiece until the thickness of the device layer calculated in the device layer thickness calculation step reaches a predetermined target thickness.

  According to the grinding apparatus of the present invention, it is provided with the thickness measuring means for measuring the thickness of the silicon carrier of the plate-like work and the adhesive layer before holding the plate-like work on the holding table. A light projecting unit that projects measurement light having a wavelength that is transmissive to the silicon carrier and the adhesive layer from the silicon carrier side of the workpiece, and first reflected light and silicon reflected by the surface of the silicon carrier. The second reflected light reflected at the interface between the carrier and the adhesive layer and the third reflected light transmitted through the silicon carrier and reflected at the interface between the adhesive layer and the device layer are received for each wavelength via the spectroscope. A light receiving unit that receives light, a first calculation unit that calculates the thickness of the silicon carrier based on a difference in optical path length between the first reflected light and the second reflected light received by the light receiving unit, and a second reflection received by the light receiving unit. Optical path length between light and third reflected light The thickness of the device layer is calculated by subtracting the sum of the thickness of the second carrier for calculating the thickness of the adhesive layer and the thickness of the silicon carrier and the thickness of the adhesive layer from the thickness of the plate-like workpiece calculated by the workpiece thickness calculator. A device layer calculating unit that calculates the thickness of the plate-like workpiece held by the holding table until the thickness calculated by the device layer calculating unit reaches a predetermined target thickness. Thus, it becomes possible to accurately grind the thickness to a predetermined target thickness.

  In addition, according to the grinding method of the present invention, the measurement light having a wavelength that is transmissive to the silicon carrier and the adhesive layer is irradiated from the silicon carrier side, and reflected by the lower surface of the silicon carrier. A first measurement step of measuring the thickness of the silicon carrier by an optical path length difference between the reflected light of 1 and the second reflected light reflected at the interface between the silicon carrier and the adhesive layer; and reflection of the measurement light A second measuring step of measuring the thickness of the adhesive layer by the optical path length difference between the second reflected light reflected by the third reflected light reflected by the interface between the adhesive layer and the device layer; Measuring the holding step of holding the silicon carrier side of the plate-like workpiece on the holding surface, the height of the upper surface of the plate-like workpiece held on the holding surface by the holding step, and the height of the holding surface; Difference between the height of the upper surface of the plate workpiece and the height of the holding surface A workpiece thickness calculating step for calculating the thickness of the plate-like workpiece, and subtracting the thickness of the silicon carrier and the thickness of the adhesive layer from the thickness of the plate-like workpiece calculated in the workpiece thickness calculating step. A device layer thickness calculating step for calculating the thickness of the device, and a grinding step for grinding the plate-like workpiece until the thickness of the device layer calculated by the device layer thickness calculating step reaches a predetermined target thickness. Thus, the thickness of the device layer can be accurately ground to a predetermined target thickness.

It is a perspective view showing the whole grinding device concerning the embodiment of the present invention. It is the perspective view which shows the whole plate-shaped workpiece processed in the grinding apparatus shown in FIG. 1, and a partial expanded sectional view. It is a figure for demonstrating the measuring method by 1st embodiment of the thickness measurement means arrange | positioned at the grinding apparatus shown in FIG. It is a partially expanded perspective view which shows 2nd embodiment of the thickness measurement means arrange | positioned at the grinding apparatus shown in FIG. It is a figure for demonstrating the measuring method by the thickness measuring means shown in FIG.

  Hereinafter, a grinding apparatus and a grinding method configured according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is an overall perspective view of a grinding apparatus according to a first embodiment of the present invention. As shown in the figure, the grinding apparatus 1 is configured to perform a series of operations including a carry-in process, a rough grinding process, a finish grinding process, a cleaning process, and a carry-out process on a plate-like workpiece W that is a workpiece. Has been. The plate-like workpiece W is formed in a substantially disc shape as shown in FIG. 2A, and a support made of silicon (Si) from the lower surface as shown in a partially enlarged sectional view in FIG. 2B. A silicon carrier 230 employed as a plate, an adhesive layer 220, and a device layer 210 in which a silicon chip laminated on a wiring board is sealed with a mold resin. For example, an adhesive made of an epoxy resin can be used for the adhesive layer 220. A cassette C containing a plurality of such plate-like workpieces W is carried into the grinding apparatus 1.

  On the front side of the base 11 of the grinding apparatus 1, a pair of cassettes C in which a plurality of plate workpieces W are accommodated are placed. Behind the pair of cassettes C, a cassette robot 16 for taking in and out the plate-like workpieces W with respect to the cassettes C is provided. A positioning mechanism 21 that positions the unprocessed plate-like workpiece W is obliquely rearward to the right of the cassette robot 16, and a cleaning mechanism that is used to wash the processed plate-like workpiece W diagonally to the left of the cassette robot 16. 26. Between the positioning mechanism 21 and the cleaning mechanism 26, there are a carrying-in means 31 for carrying the plate-shaped workpiece W before processing into the holding table 41 and a carrying-out means 36 for carrying out the processed plate-like workpiece W from the holding table 41. Is provided.

  The cassette robot 16 is configured by providing a hand portion 18 having a suction mechanism (not shown) at the tip of a robot arm 17 formed of a multi-node link. In the cassette robot 16, the unprocessed plate workpiece W is transferred from the cassette C to the positioning mechanism 21, and the processed plate workpiece W is transferred from the cleaning mechanism 26 to the cassette C.

  The positioning mechanism 21 is configured by arranging a plurality of positioning pins 23 that can move forward and backward with respect to the center of the temporary table 22 around the temporary table 22. In the positioning mechanism 21, the center of the plate-like workpiece W is centered on the center of the temporary placement table 22 by a plurality of positioning pins 23 being abutted against the outer peripheral edge of the plate-like workpiece W placed on the temporary placement table 22. Is done.

  The positioning mechanism 21 in the present embodiment is provided with a thickness measuring unit 100 configured according to the present invention, and a signal output from the thickness measuring unit 100 is sent to the control unit 85. As shown in the drawing, the thickness measuring means 100 is disposed inside the temporary table 22 and the temporary table 22 has an opening 24 through which measurement light for measuring the thickness passes.

  The configuration of the thickness measuring unit 100 will be described with reference to FIG. As shown in the drawing, the thickness measuring unit 100 emits the measuring light 121 emitted from the light emitting unit 101 upward, that is, in the Z direction. The reflecting mirror 102, the sensor head 103 that transmits the measurement light 121, the diffraction grating 104 that splits the reflected light 125 that is reflected by the plate-like workpiece W and returned, and is split by the diffraction grating 104. And an image sensor 105 (light receiving unit) that receives the light 126 for each wavelength. In addition, although illustration is abbreviate | omitted, the collimating lens which converts the measurement light 121 irradiated from the sensor head 103 into parallel light, and irradiates the plate-shaped workpiece | work W is also arrange | positioned.

  The light emitting unit 101 is, for example, a super luminescent diode (SLD), and the measurement light 121 emitted from the light emitting unit 101 has a relatively wide spectral width. The wavelength region of the measurement light 121 is selected from the wavelength region that transmits the silicon carrier constituting the plate-like workpiece W and the material of the adhesive layer (in this embodiment, epoxy resin). In the present embodiment, light in the infrared region is employed as the measurement light 121.

  The measurement light 121 applied to the plate-like workpiece W is divided into light 122 (first reflected light) reflected from the lower surface of the silicon carrier 230 located on the lowermost side and light incident into the silicon carrier 230. . The light incident into the silicon carrier 230 is divided into light 123 (second reflected light) reflected at the interface between the silicon carrier 230 and the adhesive layer 220 and light incident into the adhesive layer 220. Further, the light incident on the adhesive layer 220 is reflected at the interface between the adhesive layer 220 and the device layer 210 to become light 124 (third reflected light). Therefore, the reflected light 125 reflected and returned by the plate-like workpiece W includes the light 122 reflected from the surface of the silicon carrier 230, the light 123 reflected from the interface between the silicon carrier 230 and the adhesive layer 220, and the adhesive layer 220. The combined light is combined with the light 124 reflected at the interface with the device layer 210. Since the light 122 to 124 have different optical path lengths, the combined light is a combination of lights having different phases. . When the phases of the lights 122 to 124 are aligned, the amplitude is increased, and when the phases are shifted, the amplitude is decreased. If the wavelength is different, the phase difference is different even if the optical path length difference is the same. Therefore, the amplitude of the reflected light 125 differs depending on the wavelength of the measurement light. Therefore, by analyzing the spectrum of the reflected light 125, the optical path length difference of the lights 122 to 124 can be obtained.

  The diffraction grating 104 separates the reflected light 125 by reflecting the reflected light 125 in different directions depending on the wavelength. The image sensor 105 is configured by arranging a plurality of light receiving elements in a straight line. The image sensor 105 receives light 126 that is reflected by the diffraction grating 104 and dispersed by wavelength. Since the angle with respect to the reflection point at which the reflected light 125 is reflected by the diffraction grating 104 differs depending on the position of the light receiving element, each light receiving element receives a specific wavelength component of the reflected light 125. The image sensor 105 outputs a signal indicating the intensity of light received by each light receiving element. That is, the signal output from the image sensor 105 indicates the result of analyzing the spectrum of the reflected light 125. The thickness measuring means 100 has a configuration generally as described above, and a method for calculating the thickness will be supplemented.

  Returning to FIG. 1 and continuing the description, the carry-in means 31 is configured by providing a carry-in pad 33 provided with a suction means (not shown) at the tip of a carry-in arm 32 that can turn on the base 11. In the carry-in means 31, the plate-like workpiece W is sucked and lifted from the temporary placement table 22 by the carry-in pad 33, and the carry-in pad 33 is turned by the carry-in arm 32, whereby the plate-like workpiece W is placed on the holding table 41 at the carry-in position. It is brought in.

  The carry-out means 36 is configured by providing a carry-out pad 38 having a suction means (not shown) at the tip of a carry-out arm 37 that can turn on the base 11. In the carry-out means 36, the plate-like work W is sucked and lifted from the holding table 41 by the carry-out pad 38, and the carry-out pad 38 is turned by the carry-out arm 37, so that the plate-like work W is carried out from the holding table 41 at the carry-out position. Is done. Note that the carry-out position and the carry-in position described above are the same position.

  The cleaning mechanism 26 is configured by providing various nozzles (not shown) for injecting cleaning water and dry air toward a spinner table 27 configured to be rotatable. In the cleaning mechanism 26, the spinner table 27 holding the plate-like workpiece W is lowered into the base 11, and cleaning water is sprayed in the base 11 to wash the plate-like workpiece W, and then dry air is blown. Then, the plate-like workpiece W is dried.

  Behind the carry-in means 31 and the carry-out means 36 is provided a turntable 40 provided with three holding tables 41 at equal intervals in the circumferential direction. Below the holding table 41, a rotating means (not shown) for rotating the holding table 41 is provided. A holding surface 42 for sucking and holding the lower surface of the plate-like workpiece W is formed on the upper surface of each holding table 41.

  As the turntable 40 rotates, a loading / unloading position at which the plate-like workpiece W held on the holding table 41 is carried in and out, a rough grinding position corresponding to the rough grinding means 46, and a finish grinding corresponding to the finish grinding means 51 are obtained. Positioned sequentially.

  In addition, columns 12 and 13 are erected around the turntable 40. The column 12 is provided with a moving mechanism 61 that moves the rough grinding means 46 up and down. The moving mechanism 61 includes a pair of guide rails 62 arranged in front of the column 12 and parallel to the Z-axis direction, and a motor-driven Z-axis table 63 slidably installed on the pair of guide rails 62. Yes.

  A rough grinding means 46 is supported on the front surface of the Z-axis table 63 via a housing 64. A ball screw 65 is screwed to the back side of the Z-axis table 63, and a drive motor 66 is connected to one end of the ball screw 65. The ball screw 65 is rotationally driven by the drive motor 66, and the rough grinding means 46 is moved along the guide rail 62 in the Z-axis direction.

  Similarly, the column 13 is provided with a moving mechanism 71 that moves the finish grinding means 51 up and down. The moving mechanism 71 includes a pair of guide rails 72 arranged in front of the column 13 and parallel to the Z-axis direction, and a motor-driven Z-axis table 73 slidably installed on the pair of guide rails 72. Yes.

  A finish grinding means 51 is supported on the front surface of the Z-axis table 73 via a housing 74. A ball screw 75 is screwed to the back side of the Z-axis table 73, and a drive motor 76 is connected to one end of the ball screw 75. The ball screw 75 is rotationally driven by the drive motor 76, and the finish grinding means 51 is moved along the guide rail 72 in the Z-axis direction.

  The rough grinding means 46 and the finish grinding means 51 are configured by providing mounts 47 and 52 at the lower end of a cylindrical spindle. In the rough grinding means 46, the device layer 210 that forms the upper surface of the plate-like workpiece W held on the holding table 41 is roughly ground. On the lower surface of the mount 47 of the rough grinding means 46, a grinding wheel 49 in which a plurality of rough grinding wheels 48 are annularly arranged is rotatably mounted. The rough grinding wheel 48 is composed of, for example, a diamond grinding stone in which diamond abrasive grains are hardened with a binder such as resin bond or vitrified bond.

  Further, the finish grinding means 51 finish-grinds the upper surface of the device layer 210 of the plate-like workpiece W held on the holding table 41. On the lower surface of the mount 52 of the finish grinding means 51, a grinding wheel 54 is mounted as a finish grinding processing tool in which a plurality of finish grinding wheels 53 are annularly arranged. The finish grinding wheel 53 is formed of abrasive grains having a smaller particle diameter than the coarse grinding wheel 48. In the rough grinding process and the finish grinding process, the device layer 210 of the plate-like workpiece W is ground and thinned to a predetermined target thickness by the grinding wheels 48 and 53.

  In such a grinding apparatus 1, the plate-like workpiece W is conveyed from the cassette C to the positioning mechanism 21, and the plate-like workpiece W is centered by the positioning mechanism 21. Next, the plate-like workpiece W is carried onto the holding table 41, and the plate-like workpiece W held on the holding table 41 is positioned in the order of the rough grinding position and the finish grinding position by the rotation of the turntable 40. The plate workpiece W is roughly ground at the rough grinding position, and the plate workpiece W is finish ground at the finish grinding position. Then, the plate workpiece W is cleaned by the cleaning mechanism 26, and the plate workpiece W is carried out from the cleaning mechanism 26 to the cassette C.

  In the present embodiment, a holding table height measuring gauge (first gauge) 91 for measuring the height of the upper surface (holding surface 42) of the holding table 41 and the holding table 41 are held near the rough grinding position. A plate-like workpiece height measuring gauge (second gauge) 92 for measuring the height of the upper surface (surface to be ground) of the plate-like workpiece W is provided. The 1st gauge 91 and the 2nd gauge 92 are comprised with a contact-type gauge. Each measurement value obtained by the first gauge 91 and the second gauge 92 is output to a control unit 85 that controls the respective units of the apparatus.

  Further, in the vicinity of the finish grinding position, a holding table height measuring gauge (third gauge) 93 for measuring the upper surface (holding surface) height of the holding table 41 and a plate-like workpiece W held by the holding table 41 are also provided. A plate-like workpiece height measuring gauge (fourth gauge) 94 for measuring the height of the upper surface (surface to be ground) is provided. The third gauge 93 and the fourth gauge 94 are constituted by contact type gauges. Each value (measured value) obtained by the third gauge 93 and the fourth gauge 94 is output to the control unit 85.

  The above-described control unit 85 is configured by a computer, and a central processing unit (CPU) that performs arithmetic processing according to a control program, a read only memory (ROM) that stores a control program, etc., detected detection values, calculation results, and the like. A random access memory (RAM) that can be read and written for temporary storage, an input interface, and an output interface are provided (details are not shown). The control unit 85 includes a calculation unit 86. The calculation unit 86 is realized by a plurality of control programs stored in the ROM. For example, the calculation unit 86 calculates the total thickness of the plate-like workpiece W from values measured by the gauges 91, 92, 93, and 94, and The calculation of the thickness of the silicon carrier 230 and the adhesive layer 220 described later is also performed. The control unit 85 controls the amount of movement of the rough grinding unit 46 and the finish grinding unit 51 in the Z-axis direction according to the output result from the calculation unit 86.

  The grinding apparatus 1 of the present invention has a configuration generally as described above, and its operation will be described below.

  When grinding the plate-shaped workpiece W in the grinding apparatus 1, first, the hand unit 18 disposed at the tip of the robot arm 17 of the cassette robot 16 is operated to operate the unprocessed plate accommodated in the cassette C. The workpiece W is taken out. The plate-like workpiece W taken out from the cassette C is transported to the temporary placement table 22 of the positioning mechanism 21, and the plate-like workpiece W is placed so as to become the silicon carrier 230, the adhesive layer 220, and the device layer 210 from the lower surface. . Then, the centering of the plate-like workpiece W becomes the center of the temporary placement table 22 by the plurality of positioning pins 23 being abutted against the outer peripheral edge of the plate-like workpiece W placed on the temporary placement table 22. Is done.

  When the plate-like workpiece W is positioned, the thickness measuring unit 100 is operated to measure the thicknesses of the silicon carrier 230 and the adhesive layer 220.

  The thickness measuring unit 100 irradiates the measurement light 121 emitted from the light emitting unit 101 through the opening 24 while the plate-like workpiece W is held on the temporary table 22. As described with reference to FIG. 3, the reflected light 125, which is the combined light of the lights 122 to 124 reflected from the layers of the plate-like workpiece W by the measurement light 121 irradiated from the opening 24, is spectrally separated by the diffraction grating 104. The light 126 is received by the image sensor 105. The signal of the reflected light 125 received by the image sensor 105 is sent to the control unit 85, analyzed by the calculation unit 86, and subjected to Fourier transform to calculate each optical path length difference of the light 122 to light 124.

  Since the reflected light 125 is a combined light of the three lights 122 to 124, the calculation unit 86 calculates three optical path length differences that are the number of combinations for selecting two of the three lights 122 to 124. . The optical path length difference between the light 122 and the light 123 is twice the thickness of the silicon carrier 230. The optical path length difference between the light 123 and the light 124 is twice the thickness of the adhesive layer 220. The optical path length difference between the light 122 and the light 124 is twice the total thickness of the silicon carrier 230 and the adhesive layer 220. Therefore, half of each optical path length difference is the thickness of each layer. Here, regarding each layer constituting the plate-like workpiece W of the present embodiment, the thickness of the adhesive layer 220 is a small value with respect to the thickness of the silicon carrier 230 even if the above-described allowable thickness error is taken into consideration. I know that there is. Therefore, looking at the three optical path length differences described above, the optical path length difference between the light 122 and the light 124 is the largest, the optical path length difference between the light 122 and the light 123 is the next largest, and the optical path between the light 123 and the light 124. The difference in length is the smallest. That is, if the three optical path length differences are found, it is easily found which optical path length difference each indicates. Based on this, the thickness calculator 86 calculates the thickness T1 of the silicon carrier 230 (first measurement step), calculates the thickness T2 of the adhesive layer 220 (second measurement step), and adheres to the silicon carrier 230. A total value T1 + T2 obtained by adding the thicknesses with the agent layer 220 can be calculated. The calculation unit 86 includes a first measurement unit that performs the first measurement process and a second measurement unit that performs the second measurement process. The thicknesses T1, T2, and T1 + T2 calculated by the calculation unit 86 are stored in the memory of the control unit 85. The total value T1 + T2 obtained by adding the thicknesses of the silicon carrier 230 and the adhesive layer 220 described above may be calculated by adding the thickness T1 of the silicon carrier 230 and the thickness T2 of the adhesive layer 220 individually. However, it may be calculated directly from the optical path length difference between the light 122 and the light 124. In that case, the first measurement process and the second measurement process are performed by calculating a total value T1 + T2 obtained by adding the thicknesses of the silicon carrier 230 and the adhesive layer 220 from the optical path length difference between the light 122 and the light 124. It will be performed at the same time.

  In addition, since the wavelength of light changes with the refractive index of the substance through which light passes, and the refractive index of a substance is influenced by temperature, when the temperature change of the environment where the grinding device 1 is located is large, according to temperature Correction may be performed. In addition, since the refractive index differs depending on the substance, in this embodiment, the measured value is converted into the actual thickness by multiplying the coefficient. Specifically, the thickness measuring unit 100 of the present embodiment is set so that the thickness of silicon can be measured accurately. Since the refractive index of silicon is 3.88, whereas the refractive index of the epoxy resin constituting the adhesive layer is 1.55, the thickness of the adhesive layer calculated by the thickness measuring means 100 is calculated. The value is multiplied by a coefficient of 3.88 / 1.55 = 2.5 to calculate the thickness of the adhesive layer T2.

  Returning to FIG. 1 and continuing the description, as described above, if the thicknesses T1 and T2 of each layer of each plate-like workpiece W and the total value (T1 + T2) are measured, the plate-like workpiece on the temporary table 22 is measured. W is adsorbed by the carry-in pad 33 of the carry-in means 31 and carried onto the holding table 41 positioned at the carry-in position, and the lower surface of the plate-like workpiece W, that is, the silicon carrier 230 side is sucked into the holding surface 42 of the holding table 41. Hold (holding step).

  When the holding table 41 is moved from the loading position of the wafer W to the rough grinding position and the outer periphery of the grinding wheel 49 is positioned at a position passing through the center of the plate-like workpiece W, the holding table 41 is moved outside the plate-like workpiece W. The first gauge 91 comes into contact with the upper surface portion, and the height H1 of the upper surface of the holding table 41 is measured. Further, the second gauge 92 contacts the upper surface of the plate-like workpiece W, that is, the upper surface of the device layer 210, and the height H2 of the upper surface of the plate-like workpiece W is measured. The measurement result is output to the calculation unit 86 of the control unit 85, and the difference between the value H2 measured by the second gauge 92 and the value H1 measured by the first gauge 91 is determined from the difference ΔH1. Total thickness T is calculated (work thickness calculation step). A control program for carrying out the workpiece thickness calculation step is provided in the calculation unit 86, which becomes the workpiece thickness calculation unit of the present invention.

  Next, the grinding wheel 48 is rotated while the holding table 41 is rotated, the grinding wheel 49 is brought close to the upper surface of the plate-like workpiece W, and the grinding wheel 49 is brought into contact with the upper surface of the plate-like workpiece W. The upper surface is roughly ground by a grinding wheel 49. While executing rough grinding, the height H2 of the upper surface 81 of the plate-like workpiece W is measured in real time by the second gauge 92, and the height H1 of the holding table 41 measured immediately before the rough grinding of the plate-like workpiece W is started. The total thickness T of the current plate-like workpiece W changed by rough grinding is calculated from the difference ΔH1. Further, in the present embodiment, the calculation unit 86 performs grinding by subtracting the total value (T1 + T2) of the silicon carrier 230 and the adhesive layer that are measured and stored in advance from the total thickness T of the plate-like workpiece W. A device layer calculation unit that calculates the thickness T3 of the device layer 210 in the middle (device layer thickness calculation step) is provided. Based on the thickness T3 of the device layer 210 calculated in real time, the movement amount of the rough grinding means 46 is controlled by the control unit 85 (grinding process). By this control, the rough grinding of the wafer W is continued until the thickness T3 of the device layer 23 reaches a predetermined target thickness in the rough grinding, and when the predetermined target thickness is reached, the rough grinding means 46 rises and grinding from the plate-like workpiece W is performed. The wheel 49 is released to complete the rough grinding of the plate-like workpiece W. In addition, the predetermined target thickness in rough grinding is a thickness obtained by adding the thickness to be ground by finish grinding in the next process to the final target device layer thickness.

  After the above-described rough grinding is performed, the plate-like workpiece W held on the holding table 41 is positioned at the finish grinding position by the rotation of the turntable 40 (see FIG. 1). When the outer periphery of the grinding wheel 54 is positioned at a position passing through the center of the plate-like workpiece W, the third gauge 93 comes into contact with the upper surface of the outside of the plate-like workpiece W of the holding table 41, and the height H3 of the holding table 41 is reached. Measure. The fourth gauge 94 is in contact with the upper surface of the plate-like workpiece W, that is, the upper surface of the device layer 210 after rough grinding, and the height H4 of the upper surface of the plate-like workpiece W is measured. The measurement result is output to the control unit 85.

  Next, the grinding wheel 54 rotates while the holding table 41 rotates, the grinding wheel 54 approaches the upper surface of the plate-like workpiece W, the grinding wheel 54 comes into contact with the upper surface of the plate-like workpiece W, and the plate-like workpiece W The upper surface of each is finish-ground by the grinding wheel 54.

  At this time, the calculation unit 86 calculates the height H4 of the upper surface of the plate-like workpiece W and the holding table from the difference between the value of H4 measured by the fourth gauge 94 and the value of H3 measured by the third gauge 93. A difference ΔH3 with respect to the height H3 of the upper surface of 41 is calculated. The thickness T3 of the device layer 210 during grinding can be calculated in real time by subtracting the total value of the thickness of the silicon carrier 230 measured and stored in advance and the thickness of the adhesive layer from ΔH3. . Then, based on the calculated thickness T3 of the device layer 210, the moving amount of the finish grinding means 51 is controlled by the calculating unit 86. By this control, the finish grinding of the plate-like workpiece W is continued until the thickness T3 of the device layer 230 reaches a predetermined target thickness in the finish grinding, that is, the metal post is appropriately exposed from the surface of the device layer 210. When the target thickness is reached, the finish grinding means 51 rises, the grinding wheel 54 is released from the plate workpiece W, and the finish grinding of the plate workpiece W is completed.

  When the finish grinding for the plate-like workpiece W is completed, the holding table 41 is moved to the carry-out position, and the plate-like workpiece W is carried out by the carry-out means 36 to wash the processed plate-like workpiece W. It is conveyed to. The plate-like workpiece W conveyed to the cleaning mechanism 26 is spinner cleaned with cleaning water sprayed from a cleaning nozzle (not shown) and dried. The dried plate-like workpiece W is conveyed to a predetermined accommodation position of the cassette C by the robot arm 17 of the cassette robot 16, and the grinding process is completed.

  According to the above-described embodiment, the finish grinding means 51 can accurately grind the thickness of the device layer 210 to a predetermined target thickness. For this reason, even if the thickness of the device layer 210 formed on the plate-like workpiece W is different for each solid, the movement of the finish grinding means 51 can be controlled to be adjusted according to this difference. This device layer 210 can be accurately ground to a predetermined target thickness.

  In the first embodiment described above, the movement amount of the rough grinding means 46 and the finish grinding means 51 is controlled by the control unit 85 based on the thickness T3 of the device layer 210 calculated in real time. It is not limited. When the thickness T3 of the device layer 210 is calculated before performing the grinding step, the necessary amount of grinding to be ground based on the difference between the predetermined target thickness of the device layer 210 and the thickness T3 of the device layer 210 before processing. ΔT is determined. After the required grinding amount ΔT is determined, the upper surface of the plate-like workpiece W is ground so that the required grinding amount ΔT is ground from the total thickness T of the plate-like workpiece W calculated in real time based on the necessary grinding amount ΔT. The grinding process can be performed while monitoring the grinding amount with the second gauge and the fourth gauge at the heights H2 and H4.

  Next, a second embodiment will be described based on FIGS. In the first embodiment and the second embodiment, the thickness of the silicon carrier 230 and the adhesive layer 220 of the plate-like workpiece W is set before the plate-like workpiece W is held on the holding table 41 in the carry-in position. This is common in terms of measurement, and only the arrangement position of the thickness measuring means is different. Therefore, in the description of the second embodiment, this difference will be mainly described, and description of other identical configurations will be omitted.

  In the first embodiment described above, the thickness measuring means is disposed immediately below the temporary table 22 and the measurement light 121 is irradiated from the opening 24 of the temporary table 22 to irradiate the silicon carrier 230 of the plate-like workpiece W, the adhesive layer. A thickness of 220 was measured. On the other hand, in the second embodiment, as shown in FIG. 4, more specifically, positioning is performed on a path for carrying the plate-like workpiece W from the temporary table 22 to the holding table 41 positioned at the carry-in position. The thickness measuring means 300 is disposed at a position adjacent to the mechanism 21 and between the base 11 and the turntable 40.

  The thickness measuring unit 300 has substantially the same configuration as the thickness measuring unit 100. Specifically, as shown in FIG. 5, a light emitting unit 301 that emits measurement light 321 to the plate-like workpiece W, and a mirror 302 that reflects the measurement light 321 emitted by the light emitting unit 301 upward, that is, in the Z direction. A sensor head 303 that transmits the measurement light 321, a diffraction grating 304 that splits the reflected light 325 reflected by the measurement light 321 from the plate-like workpiece W, and an image sensor that receives the light 326 split by the diffraction grating 304. 305.

  The light emitting unit 301 is, for example, a super luminescent diode (SLD), and the measurement light 321 emitted from the light emitting unit 301 has a relatively wide spectral width. As the wavelength region of the measurement light 321, a wavelength region that transmits the material of the silicon carrier 230 and the adhesive layer 220 constituting the plate-like workpiece W is selected. In the present embodiment, measurement light in the infrared region is employed as the measurement light 321.

  As described above, in the first embodiment, the thickness of the silicon carrier 230 and the adhesive layer 220 is calculated by operating the thickness measuring unit 100 with the plate-like workpiece W placed on the temporary placement table 22. It was. In contrast, in the second embodiment, after the plate-like workpiece W is centered by the positioning mechanism 21, the plate-like workpiece W on the temporary placement table 22 is disposed on the lower surface of the carry-in pad 33 of the carry-in means 31. The thickness is measured in the middle of the path that is attracted by the suction holding surface 33a and moved toward the holding table 41 positioned at the carry-in position. Specifically, if the plate-like workpiece W is positioned above the sensor head 303 in the course of moving along the holding table 41, the carrying operation of the carry-in means 31 is stopped and the measurement is performed from the thickness measuring means 300. Irradiate light 321.

  The measurement light 321 is divided into light 322 (first reflected light) reflected by the silicon carrier 230 located on the lowermost side and light incident on the silicon carrier 230. The measurement light 321 incident on the silicon carrier 230 is divided into light 323 (second reflected light) reflected at the interface between the silicon carrier 230 and the adhesive layer 220 and light incident on the adhesive layer 220. . The light that has entered the adhesive layer 220 becomes light 324 (third reflected light) that is reflected at the interface between the adhesive layer 220 and the device layer 210. Therefore, the reflected light 325 reflected and returned by the plate-like workpiece W is light 322 reflected from the surface of the silicon carrier 230, light 323 reflected from the interface between the silicon carrier 230 and the adhesive layer 220, and the adhesive layer 220. The combined light is combined with the light 324 reflected at the interface with the device layer 210. Since the light paths 322 to 324 have different optical path lengths, the combined light is obtained by combining lights having different phases. When the phases of the light beams 322 to 324 are aligned, the amplitude is increased, and when the phases are shifted, the amplitude is decreased. The measurement light 321 emitted from the light emitting unit 301 is configured with a wavelength having a predetermined range width. When the wavelength is different, the phase difference is different even if the optical path length difference is the same. Therefore, the amplitude of the reflected light 325 differs depending on the wavelength of the measurement light 321. Therefore, by analyzing the spectrum of the reflected light 325 received by the image sensor 305, the optical path length difference between the lights 322 to 324 can be obtained. Similarly to the first embodiment, the thickness T1 of the silicon carrier 230, the thickness T2 of the adhesive layer 220, and the total value (T1 + T2) can be calculated using these optical path length differences.

  If the thickness (T1) of the silicon carrier 230, the thickness (T2) of the adhesive layer 220, and the combined value (T1 + T2) of the thickness of the silicon carrier 230 and the thickness of the adhesive layer 220 are calculated, they are stored in the control unit 85. . When the thickness of each layer is calculated, the carrying-in means 31 is actuated again, the plate-like workpiece W is moved and placed on the holding table 41, and is sucked and held by the holding table 41. After the plate-like workpiece W is sucked and held on the holding table 41, the thickness of the device layer 210 is calculated based on the total value (T1 + T2), and each process as described in the first embodiment is performed. By doing so, the plate-like workpiece W can be ground to a predetermined target thickness. When calculating the thickness of each layer by irradiating the measurement light 321, it is not always necessary to stop the operation of the carrying-in means 31, and the irradiation of the measurement light 321 and the calculation of the thickness of each layer are performed even during the operation of the carrying-in means 31. If implementation is possible, the carrying-in means 31 does not need to be stopped. Also in the second embodiment described above, the same operational effects as in the first embodiment can be achieved.

1: Grinding device 11: Base 21: Positioning mechanism 22: Temporary placement table 23: Pin 24: Opening 31: Loading means 32: Loading arm 33: Loading pad 40: Turntable 41: Holding table 42: Holding surface 85: Control Unit 86: calculating unit 100, 300: thickness measuring means 101, 301: light emitting unit 102, 302: mirror 103, 303: sensor head 104, 304: diffraction grating 105, 305: image sensor

Claims (2)

A holding table having a holding surface for holding a plate-like workpiece formed from a device layer obtained by sealing a silicon chip laminated on a wiring substrate with a silicon carrier, an adhesive layer, and a mold resin from the lower surface; Grinding means for grinding the device layer of the held plate workpiece with a grinding wheel, a holding table height measuring gauge for measuring the upper surface height of the holding table, and the upper surface height of the plate workpiece held by the holding table A workpiece thickness calculator for calculating the total thickness of the plate workpiece from the difference between the gauge for measuring the plate workpiece, the gauge for measuring the holding table, and the gauge for measuring the workpiece height; A grinding apparatus comprising:
The grinding apparatus
A thickness measuring means for measuring the thickness of the silicon carrier and the adhesive layer of the plate-like workpiece before holding the plate-like workpiece on the holding table;
The thickness measuring means includes
A light projecting unit that projects measurement light having a wavelength that is transmissive to the silicon carrier and the adhesive layer from the silicon carrier side of the plate-like workpiece, and the measurement light is reflected by the surface of the silicon carrier The second reflected light reflected at the interface between the first reflected light and the silicon carrier and the adhesive layer and the third reflected light transmitted through the silicon carrier and reflected at the interface between the adhesive layer and the device layer. A light receiving unit that receives the combined light composed of the reflected light for each wavelength via the spectrometer;
A first calculation unit that calculates a thickness of the silicon carrier based on an optical path length difference between the first reflected light and the second reflected light received by the light receiving unit;
A second calculation unit that calculates the thickness of the adhesive layer based on the optical path length difference between the second reflected light and the third reflected light received by the light receiving unit;
A device layer calculation unit that calculates the thickness of the device layer by subtracting the total value of the thickness of the silicon carrier and the thickness of the adhesive layer from the thickness of the plate workpiece calculated by the workpiece thickness calculation unit,
A grinding apparatus for grinding a plate-like workpiece held by the holding table with a grinding means until the thickness calculated by the device layer calculating unit reaches a predetermined target thickness. Hold the plate-like workpiece formed from the device layer in which the silicon chip laminated on the silicon carrier, adhesive layer and wiring board from the lower surface is sealed with mold resin on the holding surface of the holding table and grind the upper surface A method for grinding a plate-like workpiece in which the device layer has a predetermined thickness,
The first reflected light reflected from the lower surface of the silicon carrier by irradiating measurement light having a wavelength that is transmissive to the silicon carrier and the adhesive layer from the silicon carrier side, and the silicon carrier and the adhesive A first measurement step of measuring the thickness of the silicon carrier by an optical path length difference with the second reflected light reflected at the interface with the agent layer;
A second thickness of the adhesive layer is measured by a difference in optical path length between the second reflected light reflected by the reflection of the measuring light and the third reflected light reflected at the interface between the adhesive layer and the device layer. Measuring process,
Holding the silicon carrier side of the plate-like workpiece on the holding surface; and
The height of the upper surface of the plate-like workpiece held on the holding surface by the holding step and the height of the holding surface are measured, and the plate-like shape is determined from the difference between the upper surface height of the plate-like workpiece and the height of the holding surface. A workpiece thickness calculating step for calculating the thickness of the workpiece;
A device layer thickness calculating step for calculating the thickness of the device layer by subtracting the thickness of the silicon carrier and the thickness of the adhesive layer from the thickness of the plate-like workpiece calculated in the workpiece thickness calculating step;
A grinding step of grinding the plate work until the thickness of the device layer calculated by the device layer thickness calculation step reaches a predetermined target thickness;
A method for grinding a plate-like workpiece comprising: