JP2013154370A - Machining device and machining method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a machining device and a machining method not taking time and labor for changing a machining condition per workpiece even in case of a large variation in thickness of the workpieces.SOLUTION: A machining device performs machining on a workpiece. The machining device is provided including a holding means holding the workpiece, a machining means machining the workpiece held by the holding means, a weight measuring means measuring the weight of the workpiece, and a control means having a thickness calculation unit dividing the weight measured by the weight measuring means by the specific gravity and area of the workpiece to calculate the thickness of the workpiece, a machining condition selection unit selecting a machining condition for machining the workpiece based on the thickness calculated by the thickness calculation unit, and a machining means operation unit operating at least the machining means based on the machining condition selected by the machining condition selection unit.

Description

  The present invention relates to a processing apparatus and a processing method for processing a workpiece.

  Conventionally, for example, as disclosed in Patent Document 1, a technique for processing a via hole in a wafer as a workpiece is known. Patent Document 1 discloses a technique for performing a first processed hole forming step for forming a non-through hole and a second processed hole forming step for forming a via hole through the non-through hole.

  As disclosed in Patent Document 1, since processing parts such as via holes exist at a plurality of locations on the wafer, the wafer is moved as needed and laser irradiation is performed as needed according to preset processing conditions. .

JP 2008-0104089 A

  However, there is a concern that desired processing is not performed under the set processing conditions due to the presence of thickness variations in the workpiece. For example, in the case of a workpiece having a thickness greatly deviated from the average value, it is conceivable that via holes that do not penetrate are formed in the processing as disclosed in Patent Document 1.

  Therefore, it is conceivable to set the processing conditions as appropriate according to the thickness of the workpiece, but it will be very cumbersome for the operator to change and set the processing conditions manually. As a result, there is a disadvantage that the processing efficiency is lowered.

  The present invention has been made in view of the above problems, and the object of the present invention is to perform processing that does not require labor for changing processing conditions for each workpiece even when the thickness variation of the workpiece is large. An apparatus and a processing method are provided.

  According to the first aspect of the present invention, there is provided a processing apparatus for processing a workpiece, a holding means for holding the workpiece, and a processing means for processing the workpiece held by the holding means; A weight measuring unit for measuring the weight of the workpiece, a thickness calculating unit for calculating the thickness of the workpiece by dividing the weight measured by the weight measuring unit by the specific gravity and the area of the workpiece, and a thickness calculating unit A machining condition selection unit that selects a machining condition for machining the workpiece based on the thickness calculated in step 1, and a machining means operating unit that operates at least the machining means based on the machining condition selected by the machining condition selection unit. And a control device having the control means.

  According to the second aspect of the present invention, there is provided a processing method for processing a workpiece, the weight measuring step for measuring the weight of the workpiece, and the weight of the workpiece measured in the weight measuring step. A thickness calculation step for calculating the thickness of the workpiece by dividing by the specific gravity and area of the workpiece, a processing condition selection step for selecting a processing condition based on the thickness of the workpiece calculated in the thickness calculation step, And a processing step of processing the workpiece based on the processing conditions selected in the processing condition selection step.

  ADVANTAGE OF THE INVENTION According to this invention, even when the thickness dispersion | variation of a workpiece is large, the processing apparatus which does not need the effort which changes a processing condition for every workpiece is provided. And processing will be performed on the processing conditions according to a to-be-processed object, and the improvement of the processing quality which can implement | achieve desired processing reliably will be aimed at.

It is an external appearance perspective view of a laser processing apparatus. It is a perspective view which shows the wafer integrated with the flame | frame. It is a block diagram of a laser beam irradiation unit. It is a figure shown about the example of a process of the via hole to a wafer. It is a flowchart shown about the step of a processing method.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows the appearance of a laser processing apparatus 2 that can be used in the practice of the present invention.

  On the front side of the laser processing apparatus 2, an operation panel 4 is provided for an operator to input instructions to the apparatus such as processing conditions. In the upper part of the apparatus, a display monitor 6 such as a CRT on which a guidance screen for an operator and an image captured by an imaging unit described later are displayed is provided.

  As shown in FIG. 2, on the surface of the semiconductor wafer W to be processed, the first street S1 and the second street S2 are formed orthogonally, and the first street S1 and the second street S2 are formed. A number of devices D are formed in a region partitioned by.

  The wafer W is attached to a dicing tape T that is an adhesive tape, and the outer peripheral edge of the dicing tape T is attached to an annular frame F. As a result, the wafer W is supported by the annular frame F via the dicing tape T, and a plurality of wafers (for example, 25 wafers) are accommodated in the wafer cassette 8 shown in FIG. The wafer cassette 8 is placed on a cassette elevator 9 that can move up and down.

  Behind the wafer cassette 8 is disposed a loading / unloading device 10 for unloading the wafer W before laser processing from the wafer cassette 8 and loading the processed wafer into the wafer cassette 8.

  Between the wafer cassette 8 and the carry-in / out apparatus 10, a temporary placement area 12, which is an area on which a wafer to be carried in / out, is temporarily placed, is provided. An alignment device 14 for aligning with the position is arranged.

  Reference numeral 30 denotes a cleaning device, which cleans the processed wafer. In the vicinity of the temporary placement region 12, a transfer device 16 having a turning arm that sucks and transfers the annular frame F integrated with the wafer W is disposed.

  The wafer W is attracted by the transport device 16 and transported onto the chuck table 18, and is sucked by the chuck table 18, and the annular frame F is fixed by a plurality of fixing mechanisms (clamps) 19, whereby the wafer W is mounted on the chuck table 18. Retained.

  The chuck table 18 is configured to be rotatable and reciprocable in the X-axis direction, and an alignment mechanism 20 that detects a street of the wafer W to be laser-processed above the movement path of the chuck table 18 in the X-axis direction. Is arranged.

  The alignment mechanism 20 includes an imaging unit 22 that images the surface of the wafer W, and can detect a street to be laser processed by image processing such as pattern matching based on an image acquired by imaging. The image acquired by the imaging unit 22 is displayed on the display monitor 6.

  On the left side of the alignment mechanism 20, a laser beam irradiation unit 24 that irradiates a laser beam onto the wafer W held on the chuck table 18 is disposed. The casing 26 of the laser beam irradiation unit 24 accommodates laser oscillation means and the like which will be described in detail later. A condenser 28 for condensing the laser beam on the wafer to be processed is disposed at the tip of the casing 26. It is installed.

  In the casing 26 of the laser beam irradiation unit 24, as shown in the block diagram of FIG. 3, a laser oscillation means 34 and a laser beam modulation means 36 are disposed.

  As the laser oscillation means 34, a YAG laser oscillator or a YVO4 laser oscillator can be used. The laser beam modulating unit 36 includes a repetition frequency setting unit 38, a laser beam pulse width setting unit 40, and a laser beam wavelength setting unit 42.

  The repetition frequency setting means 38, the laser beam pulse width setting means 40, and the laser beam wavelength setting means 42 constituting the laser beam modulation means 36 are of known forms, and detailed description thereof is omitted in this specification.

  The wafer W that has been subjected to laser processing by the laser beam irradiation unit 24 moves the chuck table 18 in the X-axis direction, and is then held by the transfer device 32 that can move in the Y-axis direction and transferred to the cleaning device 30. The cleaning apparatus 30 cleans the wafer by rotating the wafer W at a low speed (for example, 800 rpm) while spraying water from the cleaning nozzle.

  After cleaning, the wafer W is dried at a high speed (for example, 2000 rpm) by blowing air from the air nozzle and drying the wafer W. Then, the wafer W is adsorbed by the transfer device 16 and returned to the temporary placement area 12, and then carried in and out. The apparatus 10 returns the wafer W to the original storage location of the wafer cassette 8.

  Next, a characteristic configuration in the embodiment of the present invention will be described. First, as shown in FIG. 1, a chuck table 18 serving as a holding means for holding a wafer W as a workpiece, and a laser beam irradiation unit 24 serving as a processing means for processing the wafer W held by the chuck table 18. It is set as the structure provided with.

  In addition to the above-described configuration, the thickness of the wafer W is obtained by dividing the weight measured by the weight measuring device 52 (weight measuring means) 52 and the weight measuring device 52 by the specific gravity and the area. The thickness calculation unit 54 for calculating the processing conditions, the processing condition selection unit 56 for selecting processing conditions for processing the wafer W based on the thickness calculated by the thickness calculation unit 54, and the processing conditions selected by the processing condition selection unit 56. And a control device (control means) 60 having at least a processing means operating unit 58 for operating the laser beam irradiation unit 24 based on the control means.

  More specifically, the weight measuring device 52 is for measuring the weight of the wafer W, and can be realized, for example, by providing the transfer device 16 with a known weight sensor (weighing scale). The transfer device 16 sucks and holds the wafer W carried to the temporary placement region 12 and transfers it onto the chuck table 18. In this transfer process, the weight of the wafer W can be measured.

  In this embodiment, since the wafer W is transported in a state of being fixed to the annular frame F via the dicing tape T, the weight of the single wafer W is reduced by the weight of the dicing tape T and the annular frame F. Can be specified.

  The weight of the wafer W may be specified before the processing of the wafer W is performed. In addition to realizing the weight measuring device 52 at the site of the transfer device 16, the weight known to the chuck table 18 is also known. By providing a sensor (weighing scale), the weight measuring device 52 can be realized at the site of the chuck table 18, or the weight measuring device is arranged at a location different from the laser processing device 2, so It is also conceivable to measure.

  Next, a control device (control means) 60 having a thickness calculation section 54, a processing condition selection section 56, and a processing means operating section 58 will be described. The control device 60 is realized in a form that also functions as a control device for controlling the above-described laser processing device, and may be separately provided as a control device different from the control device having the function.

  First, the thickness calculation unit 54 is for calculating the thickness of the wafer W. Specifically, the thickness of the wafer W measured by the weight measuring device 52 is divided by the specific gravity and area of the wafer W. Thus, the thickness of the wafer W is specified.

  The specific gravity and area of the wafer W for calculating the thickness of the wafer W are stored in advance in the thickness calculator 54 for each type of wafer W. Note that the weight of the wafer W is calculated by multiplying “area”, “specific gravity”, and “thickness”.

For example, when the workpiece is a silicon wafer having a diameter of 8 inches (20.32 cm) and an “area” of about 324.13 cm ² , the “specific gravity” is stored as 2.3 g / cm ^3, and the weight measuring device 52 Is calculated as 7.38 g, the thickness calculator 54 calculates “thickness” as 99 μm.

  The “area” and the “specific gravity” corresponding to the type of the workpiece (wafer W) whose thickness is to be measured must be recognized by the thickness calculator 54. For example, the recognition may be performed by the thickness calculation unit 54 by manual input by an operator before the start of processing, or the barcode of the wafer cassette 8 may be automatically read and recognized by the thickness calculation unit 54. It is not particularly limited.

  The processing condition selection unit 56 has a function of selecting processing conditions for processing the wafer W based on the “thickness” calculated by the thickness calculation unit 54.

  The processing conditions are a database of various “conditions” for performing predetermined processing in association with the type of workpiece and the “thickness”, and are read by the processing condition selection unit 56 as appropriate. It is conceivable that the machining conditions stored in the database are stored in a memory (not shown) such as a memory provided in the machining condition selection unit 56 or an external storage device. The following processing conditions may be considered as databased processing conditions.

  When the above-mentioned laser processing apparatus 2 (see FIG. 1) is used to form a via hole on a wafer by irradiating a laser beam, the laser beam output, energy density, wafer feed speed (chuck table processing feed) Speed), the number of pulses of laser beam irradiation, etc. are one of the “conditions”.

  When the above-described laser processing apparatus 2 (see FIG. 1) is used to form a modified layer at a predetermined position in the wafer thickness direction by laser beam irradiation, or when a laser processing groove having a predetermined depth is formed. The laser beam output and energy density, the wafer feed rate (chuck table processing feed rate), the focal position of the laser beam, etc. are among the “conditions”.

  When performing a grooving of a predetermined depth on the wafer with a rotating cutting blade (rotating cutting blade) (such as half-cut processing before grinding), the height position of the cutting blade, The feed rate (work feed rate of the chuck table), the rotation speed of the cutting blade, etc. are one of the “conditions”.

  When cutting (dicing) the wafer with a rotating cutting blade (rotating cutting blade), the cutting blade height position, wafer feed speed (chuck table processing feed speed), cutting blade The number of rotations is one of the “conditions”.

  When performing cutting (bite cutting) to thin the wafer to a predetermined thickness with a rotating bite wheel (cutting bite), the height position of the bite at the first processing feed, the bite to the wafer The cutting amount, the number of repetitions of machining feed (number of passes), etc. are one of the “conditions”.

  When grinding processing (grinding wheel grinding) to thin the wafer to a predetermined thickness with a rotating grinding wheel (grinding wheel), the height position of the grinding wheel, the grinding amount, etc. are one of the “conditions”. .

Furthermore, as a more specific example, as shown in FIG. 4, if the via hole VH is formed in the bonding pad BP on the wafer W whose “thickness” is calculated to be 99 μm, the following processing conditions are processed. It is selected from the storage means by the condition selection unit 56.
Light source: YAG laser Wavelength: 355 nm (third harmonic of YAG laser)
Energy density: 40-60 J / cm ²
Processing amount per pulse: 3μm
Number of irradiation pulses: 33

  In this processing condition, since a groove of 3 μm is formed per pulse, irradiation of 33 pulses (33 times) is required to form a 99 μm via hole VH. . The number of irradiation pulses (33 pulses) is obtained by an operation of dividing the “thickness” of 99 μm by the “processing amount per pulse” of 3 μm. This operation is stored in the storage means in advance as a processing condition. In addition, the processing condition selection unit 56 may execute the processing each time based on the “thickness” and the “processing amount per pulse”.

  The processing means operating unit 58 has a function of operating the laser beam irradiation unit 24 based on the processing conditions selected by the processing condition selecting unit 56. In the present embodiment, the laser beam irradiation unit 24 having the configuration shown in FIG. 3 is controlled by the processing means operating unit 58, and laser processing based on processing conditions is performed.

  By using the above configuration, the following processing method can be implemented. That is, as shown in FIG. 5, a processing method for processing a wafer W, which is a workpiece, is a weight measurement step ST1 for measuring the weight of the wafer W, and the wafer W measured in the weight measurement step ST1. A thickness calculating step ST2 for calculating the thickness of the wafer W by dividing the weight by the specific gravity and the area of the wafer W, and a processing condition selecting step for selecting a processing condition based on the thickness of the wafer W calculated in the thickness calculating step ST2. ST3 and processing step ST4 for processing the wafer W based on the processing conditions selected in the processing condition selection step ST3 are performed.

  And, according to the processing method for carrying out each of the above steps, even when individual thickness variations of the wafer W as a workpiece are large, the processing is performed according to the processing conditions corresponding to the individual wafers W. Processing is performed according to processing conditions corresponding to the type and thickness of individual wafers W, and processing quality can be improved so that desired processing can be realized with certainty.

  In the formation of the via hole VH shown in FIG. 4, the via hole VH that reliably reaches the bonding pad BP can be formed. In addition, since unnecessary laser beam irradiation can be eliminated and no unnecessary (excessive) machining occurs, the machining time can be optimized (shortened).

  Further, according to the above-described apparatus configuration, since the processing conditions are automatically selected, even when the thickness variation of the wafer W is large, a processing apparatus that does not require the trouble of changing the processing conditions for each wafer W is provided. . Then, the processing is performed under the processing conditions corresponding to the wafer W, and the processing quality can be improved so that the desired processing can be surely realized.

  In the above description, the embodiment has been described using a laser processing apparatus for forming a via hole for forming a via hole, but the embodiment is not limited thereto, and as described in relation to the above processing conditions, The present invention can also be implemented in a laser processing apparatus, a cutting apparatus, a cutting tool, a grinding apparatus, a polishing apparatus, or the like that forms a modified layer or a laser processing groove.

2 Laser processing device 16 Conveyance device 18 Chuck table 24 Laser beam irradiation unit 52 Weight measurement device 54 Thickness calculation unit 56 Processing condition selection unit 58 Processing means operation unit 60 Control device W wafer

Claims (2)

A processing device for processing a workpiece,
Holding means for holding the workpiece;
Processing means for processing the workpiece held by the holding means;
A weight measuring means for measuring the weight of the workpiece;
A thickness calculator for calculating the thickness of the workpiece by dividing the weight measured by the weight measuring means by the specific gravity and area of the workpiece;
A processing condition selection unit that selects processing conditions for processing the workpiece based on the thickness calculated by the thickness calculation unit;
Control means having a processing means operating section for operating at least the processing means based on the processing conditions selected by the processing condition selection section;
A processing apparatus comprising: A processing method for processing a workpiece,
A weight measuring step for measuring the weight of the workpiece;
A thickness calculating step of calculating the thickness of the workpiece by dividing the weight of the workpiece measured in the weight measuring step by the specific gravity and area of the workpiece;
A machining condition selection step for selecting a machining condition based on the thickness of the workpiece calculated in the thickness calculation step;
A processing step of processing the workpiece based on the processing conditions selected in the processing condition selection step;
A processing method characterized by comprising:

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