JP2008004822A - Method for setting processing condition of wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for setting a processing condition of a wafer for forming two laser processing grooves at a predetermined position along a street. <P>SOLUTION: The method for setting the processing condition for forming two laser processing grooves 95 along the street includes: the street detection step of imaging the street to detect a center L1 of the street; the center interval setting step of setting a center interval of the two laser processing grooves 95 to be formed on both sides of the center L1 of the detected street; the processing groove forming step; the inside interval measuring step of imaging the street by an imaging means 6 to measure an inside interval β of the two laser processing grooves 95 formed in the street; and an outside interval calculating step of acquiring an outside interval γ of the two laser processing grooves 95 by γ=2α-β, when a center interval of the two laser processing grooves 95 obtained by the center interval setting step is denoted as α and the inside interval of the two laser processing grooves 95 measured by the inside interval measuring step is denoted by β. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wafer processing condition setting method for setting processing conditions for forming two laser processing grooves along a street formed on the surface of a wafer such as a semiconductor wafer.

  As is well known to those skilled in the art, in a semiconductor device manufacturing process, a semiconductor in which a plurality of devices such as ICs and LSIs are formed in a matrix by a laminated body in which an insulating film and a functional film are laminated on the surface of a semiconductor substrate such as silicon. A wafer is formed. In the semiconductor wafer formed in this way, the above devices are partitioned by dividing lines called streets, and individual devices are manufactured by dividing along the streets.

  Such division along the street of the semiconductor wafer is usually performed by a cutting device called a dicer. This cutting apparatus includes a chuck table for holding a semiconductor wafer as a workpiece, a cutting means for cutting the semiconductor wafer held on the chuck table, and a movement for relatively moving the chuck table and the cutting means. Means. The cutting means includes a rotating spindle that is rotated at a high speed and a cutting blade attached to the spindle. The cutting blade is composed of a disk-shaped base and an annular cutting edge mounted on the outer periphery of the side surface of the base. The cutting edge is formed by fixing diamond abrasive grains having a grain size of about 3 μm, for example, by electroforming. ing.

  Recently, in order to improve the processing capability of devices such as IC and LSI, inorganic films such as SiOF and BSG (SiOB) and polymer films such as polyimide and parylene are formed on the surface of a semiconductor substrate such as silicon. A semiconductor wafer in a form in which a device is formed by a laminated body in which a low dielectric constant insulator film (Low-k film) made of an organic film and a functional film for forming a circuit is laminated has been put into practical use.

  Since the Low-k film described above is different from the material of the wafer, it is difficult to cut simultaneously with a cutting blade. That is, the low-k film is very fragile like mica, so when the cutting blade cuts along the street, the low-k film peels off, and this peeling reaches the circuit, causing fatal damage to the device. There is a problem.

In order to solve the above problem, two laser-processed grooves are formed along the streets formed in the semiconductor wafer to divide the laminate, and a cutting blade is positioned between the two laser-processed grooves. A wafer dividing method has been proposed in which a semiconductor wafer is cut along a street by moving a cutting blade and a semiconductor wafer relative to each other. (For example, refer to Patent Document 1.)
JP-A-2005-64231

  Thus, in order to accurately form the two laser processing grooves along the street having a width of several tens of μm, it is necessary to set the processing conditions precisely. Whether or not the two laser-processed grooves are accurately formed at a predetermined position on the street is confirmed by imaging the street on which the two laser-processed grooves are formed by an image pickup means constituted by an imaging device (CCD). is doing. However, in a wafer in which an individual device formed on the surface of a semiconductor substrate is coated with polyimide resin or the like, a considerable level difference is generated between the device and the street, and when the street is imaged, a device shadow is created on the street. This shadow overlaps the outline of the two laser-processed grooves formed on the street, and the outside of the two laser-processed grooves cannot be recognized. As a result, it becomes difficult to set processing conditions such as setting the width of the laser processing groove.

  The present invention has been made in view of the above-mentioned facts, and its main technical problem is to set processing conditions for a wafer that can set processing conditions for forming two laser processing grooves at predetermined positions along the street. Is to provide a method.

In order to solve the main technical problem, according to the present invention, a chuck table for holding a wafer, a laser beam irradiation means for irradiating a laser beam to the wafer held on the chuck table, the chuck table, and the laser beam irradiation means, Is held by the chuck table, a machining feed means that moves relative to the machining feed direction, an index feed means that moves the chuck table and the laser beam irradiation means relatively in an index feed direction perpendicular to the machining feed direction, and the chuck table And a laser processing apparatus having an imaging means for imaging the wafer, and two strips along the street of the wafer in which devices are formed in a plurality of regions partitioned by a plurality of streets formed in a lattice pattern on the surface. Wafer processing to set processing conditions for forming laser processing grooves A matter setting method,
A street detection step of imaging the street formed on the wafer held on the chuck table by the imaging means and detecting the center of the street;
A center interval setting step for setting the center interval of the two laser processing grooves to be formed on both sides of the center of the street detected by the street detection step;
A processing groove forming step of operating the laser beam irradiation means, the processing feeding means, and the indexing feeding means to form two laser processing grooves at the center interval set by the center interval setting step on both sides of the center of the street;
An inner interval measuring step in which the processed groove forming step is performed and the street is imaged by the imaging means, and an inner interval between the two laser processed grooves formed in the street is measured;
When the center interval of the two laser processing grooves set in the center interval setting step is α and the inner interval of the two laser processing grooves measured in the inner interval measurement step is β, two laser processing An outer interval calculating step of obtaining an outer interval γ of the groove by γ = 2α−β,
A method for setting processing conditions for a wafer is provided.

  In the wafer processing condition setting method according to the present invention, there is a considerable step between the device formed on the wafer and the street, and even if a shadow of the device is formed on the street when the street is imaged, it is formed on the street. In addition, it is possible to accurately determine the outer distance between the two laser-processed grooves. Therefore, when the center interval of the two laser processing grooves is set, the street formed on the wafer is adjusted by adjusting the processing conditions such as the focused spot diameter, output and processing feed rate of the laser beam to be irradiated. It is possible to set appropriate processing conditions that can form two laser processing grooves in the predetermined region. In addition, when the condensing spot diameter, output and processing feed speed of the laser beam to be irradiated are set, the predetermined area of the street formed on the wafer is adjusted by adjusting the center interval of the two laser processing grooves. It is possible to set appropriate processing conditions that can form two laser processing grooves.

  The wafer processing condition setting method according to the present invention will be described below in more detail with reference to the accompanying drawings.

  FIG. 1 is a perspective view of a laser processing apparatus for carrying out a wafer processing condition setting method according to the present invention. A laser processing apparatus 1 shown in FIG. 1 includes a stationary base 2, a chuck table mechanism 3 that is disposed on the stationary base 2 so as to be movable in a machining feed direction indicated by an arrow X, and holds a workpiece. A laser beam irradiation unit support mechanism 4 disposed on the table 2 so as to be movable in an index feed direction indicated by an arrow Y perpendicular to the direction indicated by the arrow X, and movable to the laser beam unit support mechanism 4 in a direction indicated by an arrow Z And a laser beam irradiation unit 5 disposed in the.

  The chuck table mechanism 3 includes a pair of guide rails 31, 31 arranged in parallel along the machining feed direction indicated by the arrow X on the stationary base 2, and the arrow X on the guide rails 31, 31. A first slide block 32 movably disposed in the processing feed direction; and a second slide block 33 disposed on the first slide block 32 movably in the index feed direction indicated by an arrow Y; A cover table 35 supported by a cylindrical member 34 on the second sliding block 33 and a chuck table 36 as a workpiece holding means are provided. The chuck table 36 includes a suction chuck 361 formed of a porous material, and holds, for example, a disk-shaped semiconductor wafer, which is a workpiece, on the suction chuck 361 by suction means (not shown). . The chuck table 36 configured as described above is rotated by a pulse motor (not shown) disposed in the cylindrical member 34. The chuck table 36 is provided with a clamp 362 for fixing an annular frame described later.

  The first sliding block 32 is provided with a pair of guided grooves 321 and 321 fitted to the pair of guide rails 31 and 31 on the lower surface thereof, and in the index feed direction indicated by an arrow Y on the upper surface thereof. A pair of guide rails 322 and 322 formed in parallel with each other are provided. The first sliding block 32 configured in this way is processed by the arrow X along the pair of guide rails 31, 31 when the guided grooves 321, 321 are fitted into the pair of guide rails 31, 31. It is configured to be movable in the feed direction. The chuck table mechanism 3 in the illustrated embodiment includes a machining feed means 37 for moving the first sliding block 32 along the pair of guide rails 31 and 31 in the machining feed direction indicated by the arrow X. The processing feed means 37 includes a male screw rod 371 disposed in parallel between the pair of guide rails 31 and 31, and a drive source such as a pulse motor 372 for rotationally driving the male screw rod 371. One end of the male screw rod 371 is rotatably supported by a bearing block 373 fixed to the stationary base 2, and the other end is connected to the output shaft of the pulse motor 372 by transmission. The male screw rod 371 is screwed into a penetrating female screw hole formed in a female screw block (not shown) provided on the lower surface of the central portion of the first sliding block 32. Therefore, when the male screw rod 371 is driven to rotate forward and backward by the pulse motor 372, the first sliding block 32 is moved along the guide rails 31, 31 in the machining feed direction indicated by the arrow X.

  The laser processing apparatus in the illustrated embodiment includes a processing feed amount detecting means 374 for detecting the processing feed amount of the chuck table 36. The processing feed amount detection means 374 includes a linear scale 374a disposed along the guide rail 31, and a read head disposed along the linear scale 374a along with the first sliding block 32 disposed along the first sliding block 32. 374b. In the illustrated embodiment, the reading head 374b of the feed amount detecting means 374 sends a pulse signal of one pulse every 1 μm to the control means described later. Then, the control means to be described later detects the machining feed amount of the chuck table 36 by counting the input pulse signals. When the pulse motor 372 is used as the drive source of the machining feed means 37, the machining feed amount of the chuck table 36 is counted by counting the drive pulses of the control means to be described later that outputs a drive signal to the pulse motor 372. Can also be detected. When a servo motor is used as a drive source for the machining feed means 37, a pulse signal output from a rotary encoder that detects the rotation speed of the servo motor is sent to a control means described later, and the pulse signal input by the control means. By counting, the machining feed amount of the chuck table 36 can also be detected.

  The second sliding block 33 is provided with a pair of guided grooves 331 and 331 which are fitted to a pair of guide rails 322 and 322 provided on the upper surface of the first sliding block 32 on the lower surface thereof. By fitting the guided grooves 331 and 331 to the pair of guide rails 322 and 322, the guided grooves 331 and 331 are configured to be movable in the indexing and feeding direction indicated by the arrow Y. The chuck table mechanism 3 in the illustrated embodiment is for moving the second slide block 33 along the pair of guide rails 322 and 322 provided in the first slide block 32 in the index feed direction indicated by the arrow Y. First index feeding means 38 is provided. The first index feed means 38 includes a male screw rod 381 disposed in parallel between the pair of guide rails 322 and 322, and a drive source such as a pulse motor 382 for rotationally driving the male screw rod 381. It is out. One end of the male screw rod 381 is rotatably supported by a bearing block 383 fixed to the upper surface of the first sliding block 32, and the other end is connected to the output shaft of the pulse motor 382. The male screw rod 381 is screwed into a penetrating female screw hole formed in a female screw block (not shown) provided on the lower surface of the central portion of the second sliding block 33. Therefore, when the male screw rod 381 is driven to rotate forward and reversely by the pulse motor 382, the second slide block 33 is moved along the guide rails 322 and 322 in the index feed direction indicated by the arrow Y.

  The laser processing apparatus in the illustrated embodiment includes index feed amount detection means 384 for detecting the index processing feed amount of the second sliding block 33. The index feed amount detecting means 384 includes a linear scale 384a disposed along the guide rail 322 and a read head disposed along the linear scale 384a along with the second sliding block 33 disposed along the second sliding block 33. 384b. In the illustrated embodiment, the reading head 384b of the feed amount detection means 384 sends a pulse signal of one pulse every 1 μm to the control means described later. Then, the control means described later detects the index feed amount of the chuck table 36 by counting the input pulse signals. When the pulse motor 382 is used as the drive source of the first indexing and feeding means 38, the drive table of the chuck table 36 is counted by counting the drive pulses of the control means to be described later that outputs a drive signal to the pulse motor 382. The index feed amount can also be detected. When a servo motor is used as a drive source for the machining feed means 37, a pulse signal output from a rotary encoder that detects the rotation speed of the servo motor is sent to a control means described later, and the pulse signal input by the control means. It is possible to detect the index feed amount of the chuck table 36 by counting.

  The laser beam irradiation unit support mechanism 4 includes a pair of guide rails 41, 41 arranged in parallel along the indexing feed direction indicated by the arrow Y on the stationary base 2, and the arrow Y on the guide rails 41, 41. The movable support base 42 is provided so as to be movable in the direction indicated by. The movable support base 42 includes a movement support portion 421 that is movably disposed on the guide rails 41, 41, and a mounting portion 422 that is attached to the movement support portion 421. The mounting portion 422 is provided with a pair of guide rails 423 and 423 extending in the direction indicated by the arrow Z on one side surface in parallel. The laser beam irradiation unit support mechanism 4 in the illustrated embodiment includes a second index feed means 43 for moving the movable support base 42 along the pair of guide rails 41, 41 in the index feed direction indicated by the arrow Y. is doing. The second index feed means 43 includes a male screw rod 431 disposed in parallel between the pair of guide rails 41, 41, and a drive source such as a pulse motor 432 for rotationally driving the male screw rod 431. It is out. One end of the male screw rod 431 is rotatably supported by a bearing block (not shown) fixed to the stationary base 2, and the other end is connected to the output shaft of the pulse motor 432. The male screw rod 431 is screwed into a female screw hole formed in a female screw block (not shown) provided on the lower surface of the central portion of the moving support portion 421 constituting the movable support base 42. For this reason, when the male screw rod 431 is driven to rotate forward and backward by the pulse motor 432, the movable support base 42 is moved along the guide rails 41, 41 in the index feed direction indicated by the arrow Y.

  The laser beam irradiation unit 5 in the illustrated embodiment includes a unit holder 51 and laser beam irradiation means 52 attached to the unit holder 51. The unit holder 51 is provided with a pair of guided grooves 511 and 511 that are slidably fitted to a pair of guide rails 423 and 423 provided in the mounting portion 422. By being fitted to the guide rails 423 and 423, the guide rails 423 and 423 are supported so as to be movable in the direction indicated by the arrow Z.

  The laser beam irradiation unit 5 in the illustrated embodiment includes a moving means 53 for moving the unit holder 51 along the pair of guide rails 423 and 423 in the direction indicated by the arrow Z (Z-axis direction). The moving means 53 includes a male screw rod (not shown) disposed between the pair of guide rails 423 and 423, and a drive source such as a pulse motor 532 for rotationally driving the male screw rod. By driving the male screw rod (not shown) in the forward and reverse directions by the motor 532, the unit holder 51 and the laser beam irradiation means 52 are moved along the guide rails 423 and 423 in the direction indicated by the arrow Z (Z-axis direction). In the illustrated embodiment, the laser beam irradiation means 52 is moved upward by driving the pulse motor 532 forward, and the laser beam irradiation means 52 is moved downward by driving the pulse motor 532 in reverse. Yes.

  The illustrated laser beam application means 52 includes a cylindrical casing 521 arranged substantially horizontally. Further, as shown in FIG. 2, the laser beam irradiation means 52 is oscillated by the pulse laser beam oscillation means 522 disposed at the tip of the casing 521 and the pulse laser beam oscillation means 522 and the transmission optical system 523 disposed in the casing 521. And a condenser 524 for irradiating the workpiece held on the chuck table 36 with the pulsed laser beam. The pulse laser beam oscillation means 522 is composed of a pulse laser beam oscillator 522a composed of a YAG laser oscillator or a YVO4 laser oscillator, and a repetition frequency setting means 522b attached thereto. This repetition frequency setting means 522b is controlled by the control means described later. The transmission optical system 523 includes an appropriate optical element such as a beam splitter.

  Returning to FIG. 1, the description is continued. At the tip of the casing 521 constituting the laser beam irradiation means 52, an imaging means 6 for detecting a processing region to be laser processed by the laser beam irradiation means 52 is disposed. The image pickup means 6 is composed of an image pickup device (CCD) or the like, and sends the picked up image signal to the control means 8.

  The control means 8 is constituted by a computer, and a central processing unit (CPU) 81 that performs arithmetic processing according to a control program, a read-only memory (ROM) 82 that stores a control program and the like, and a design value of a workpiece to be described later. A readable / writable random access memory (RAM) 83 that stores data, calculation results, and the like, a counter 84, an input interface 85, and an output interface 86 are provided. Detection signals from the machining feed amount detection means 374, the index feed amount detection means 384, the imaging means 6 and the like are input to the input interface 85 of the control means 8. A control signal is output from the output interface 86 of the control means 8 to the pulse motor 372, pulse motor 382, pulse motor 432, pulse motor 532, laser beam irradiation means 52, display means 80, and the like. The random access memory (RAM) 83 includes a storage area for storing detection value data and processing condition data, which will be described later.

Next, the wafer processed by the laser processing apparatus 1 described above will be described with reference to FIGS. A semiconductor wafer 9 shown in FIG. 3 and FIG. 4 includes a plurality of devices 92 such as ICs and LSIs in a matrix form by a laminated body 91 in which an insulating film and a functional film for forming a circuit are laminated on the surface of a semiconductor substrate 90 such as silicon. Is formed. Each device 92 is partitioned by streets 93 formed in a lattice shape. In the illustrated embodiment, the insulating film forming the laminate 91 is an organic film such as an SiO ₂ film, an inorganic film such as SiOF or BSG (SiOB), or a polymer film such as polyimide or parylene. It is made of a low dielectric constant insulator film (Low-k film) made of the above film. The surface of each device 92 is coated with a resin film 94 such as polyimide resin.

  In order to process the semiconductor wafer 9 described above with the laser processing apparatus 1, the semiconductor wafer 9 is attached to a protective tape 12 mounted on an annular frame 11 as shown in the figure. At this time, the semiconductor wafer 9 is bonded to the protective tape 12 with the front surface 9a facing up.

Next, a processing condition setting method for setting processing conditions for forming two laser processing grooves at outer intervals larger than the thickness of the cutting blade described later along the street 93 of the semiconductor wafer 9 will be described.
First, as shown in FIG. 5, the semiconductor wafer 9 supported on the annular frame 11 via the protective tape 12 is placed on the chuck table 36 of the laser processing apparatus 1 shown in FIG. Then, by operating a suction means (not shown), the semiconductor wafer 9 is sucked and held on the chuck table 36 via the protective tape 12. The annular frame 11 is fixed by a clamp 362.

  As described above, the chuck table 36 that sucks and holds the semiconductor wafer 9 is positioned immediately below the imaging unit 6 by the operation of the processing feed unit 37. When the chuck table 36 is positioned immediately below the image pickup means 6, the image pickup means 6 and the control means 8 execute an alignment operation for detecting a processing region to be laser processed on the semiconductor wafer 9. That is, the imaging unit 6 and the control unit 8 align the street 93 formed in the predetermined direction of the semiconductor wafer 9 with the condenser 524 of the laser beam irradiation unit 52 that irradiates the laser beam along the street 93. Image processing such as pattern matching is performed to align the laser beam irradiation position. The alignment of the laser beam irradiation position is similarly performed on the street 93 formed on the semiconductor wafer 9 and extending at right angles to the predetermined direction. Since the above-described alignment has no feature points on the street 93, the positional relationship with the street 93 is stored in advance in the memory of the control means using the feature points of the device 92 as a key pattern in the same manner as in the prior art. Thus, the street 93 is indirectly detected.

  As described above, when the street 93 formed on the semiconductor wafer 9 held on the chuck table 36 is detected and the alignment of the laser beam irradiation position is performed, the street 93 is imaged by the imaging means 6, and the street is captured. A street detection step of detecting the center of 93 is performed. That is, as shown in FIG. 6A, the chuck table 36 is positioned immediately below the imaging means 6, and the predetermined street 93 formed on the semiconductor wafer 9 held on the chuck table 36 is imaged by the imaging means 6. . The captured image information is sent to the control means 8 and displayed on the display means 80 as shown in FIG. As shown in FIG. 6B, the street 93 actually has a width B, but since there is a step between the street 92 and the device 92, shadows A1 and A1 are formed on both sides of the street 93. The Thus, although the full width of the street 93 cannot be confirmed, the center L1 of the street 93 is detected based on the area A2 that is not shaded. That is, since the shadow portions A1 and A1 formed on both sides of the street 93 are the same, the center of the width of the non-shadowed area A2 can be regarded as the center L1 of the street 93.

  If the center L1 of the street 93 is detected by carrying out the street detection step described above, a center interval setting step for setting the center interval of the two laser processing grooves to be formed on both sides of the street center is carried out. . That is, as shown in FIG. 7, the center interval α between the two laser processing grooves centering on the center L1 of the street 93 is set. Accordingly, the first laser beam irradiation position La is set on one side of the center L1 of the street 93 at a position α / 2 from the center L1, and the position on the other side of the center L1 of the street 93 is a position α / 2 from the center L1. To the second laser beam irradiation position Lb. The first laser beam irradiation position La and the second laser beam irradiation position Lb at the center L 1 of the street 93 are stored in a random access memory (RAM) 83 of the control means 8.

Next, a laser processing groove forming step for forming two laser processing grooves at the center interval α set by the center interval setting step is performed. The laser processing groove forming process will be described with reference to FIGS.
The chuck table 36 holding the semiconductor wafer 9 is moved to the laser beam irradiation region where the condenser 524 of the laser beam irradiation means 52 for irradiating the laser beam is located, and the first laser beam irradiation position La set on the predetermined street 93 is set. It is positioned directly below the condenser 524. At this time, as shown in FIG. 7A, the semiconductor wafer 9 has a first laser beam irradiation position La set on the street 93 at one end (the left end in FIG. 8A) immediately below the condenser 524. It is positioned to be located at. Next, the chuck table 36 is moved at a predetermined processing feed rate in the direction indicated by the arrow X1 in FIG. 8A while irradiating a pulsed laser beam from the condenser 524 of the laser beam irradiation means 52. When the other end of the first laser beam irradiation position La (the right end in FIG. 7A) reaches a position directly below the condenser 524, the irradiation of the pulse laser beam is stopped and the movement of the chuck table 36 is stopped. . In this laser processing groove forming step, the condensing point P of the pulse laser beam is matched with the vicinity of the surface of the street 93.

  Next, the chuck table 36 is moved in the direction perpendicular to the paper surface (index feed direction) by the center distance α (index feed amount), and the second set on the street 93 as shown in FIG. 8B. The laser beam irradiation position Lb is positioned directly below the condenser 524. Then, while irradiating a pulse laser beam from the condenser 524 of the laser beam irradiation means 52, the chuck table 36 is moved at a predetermined processing feed speed in the direction indicated by the arrow X2 in FIG. When the other end of Lb (the left end in FIG. 8A) reaches a position directly below the condenser 524, the irradiation of the pulse laser beam is stopped and the movement of the chuck table 36 is stopped.

  By performing the above-described laser processing groove forming step, the street 93 of the semiconductor wafer 9 has a first laser processing groove 95a and a second laser processing groove 95b deeper than the thickness of the stacked body 91 as shown in FIG. Two laser processing grooves are formed. The first laser processing groove 95a is formed around the first laser beam irradiation position La, and the second laser processing groove 95b is formed around the second laser beam irradiation position Lb. Accordingly, the center distance between the first laser processing groove 95a and the second laser processing groove 95b is α.

In addition, the said laser processing groove | channel formation process is performed on the following processing conditions, for example.
Laser light source: YVO4 laser or YAG laser Wavelength: 355 nm
Output: 0.4W
Repetition frequency: 100 kHz
Condensing spot diameter: φ5μm
Processing feed rate: 100 mm / sec Center interval (α): 20 μm

  If the above-mentioned laser processing groove forming step is performed, the street 93 in which the first laser processing groove 95a and the second laser processing groove 95b are formed is imaged by the imaging means 6, and the first formed on the street 93 is captured. An inner distance measuring step for measuring the inner distance between the laser processing groove 95a and the second laser processing groove 95b is performed. That is, the chuck table 36 is positioned immediately below the imaging means 6, and the first laser processing groove 95 a and the second laser processing groove 95 b of the semiconductor wafer 9 held on the chuck table 36 by the imaging means 6 are formed. The street 93 is imaged. This captured image information is sent to the control means 8 and displayed on the display means 80 as shown in FIG. As shown in FIG. 10, the first laser processed groove 95 a and the second laser processed groove 95 b formed in the street 93 appear as shadows. However, since there is a step between the street 93 and the device 92, Since shadow portions A1 and A1 are formed on both sides, it is impossible to detect the outside of the first laser processing groove 95a and the second laser processing groove 95b. However, since the inner side A3 of the first laser processing groove 95a and the second laser processing groove 95b can be clearly recognized, the inner distance β between the first laser processing groove 95a and the second laser processing groove 95b is set. taking measurement.

  Next, the center interval α of the two laser processing grooves (first laser processing groove 95a and second laser processing groove 95b) set in the center interval setting step and the two items measured in the inner interval measuring step. An outer interval calculation step for obtaining the outer interval of the two laser processed grooves based on the inner interval β of the laser processed grooves (first laser processed groove 95a and second laser processed groove 95b) is performed. That is, the first laser processing groove 95a and the second laser processing groove 95b are formed symmetrically about the first laser beam irradiation position La and the second laser beam irradiation position Lb, respectively, as shown in FIG. The control means 8 can obtain the outer interval γ by γ = 2α−β based on the center interval α and the inner interval β of the first laser processing groove 95a and the second laser processing groove 95b. Note that the widths of the first laser processing groove 95a and the second laser processing groove 95b vary depending on processing conditions such as the focused spot diameter of the laser beam to be irradiated, the output and the processing feed rate, and therefore the first laser processing groove 95a. The inner interval β and the outer interval γ of the second laser processing groove 95b also vary depending on the processing conditions.

  The outer distance γ obtained as described above needs to be formed in a range wider than the thickness C of the cutting blade 10 and narrower than the width B of the street 93 as shown in FIG. That is, if the outer interval γ is smaller than the thickness C of the cutting blade 10, the function due to the formation of the first laser processing groove 95 a and the second laser processing groove 95 b is not achieved, and the outer interval γ is the width of the street 93. If it is wider than B, the laser-processed groove may reach the device 92 and deteriorate the quality of the device. Therefore, based on the outer distance γ between the first laser processing groove 95a and the second laser processing groove 95b obtained as described above, the focused spot diameter of the laser beam to be irradiated, the output and the processing feed speed, or two items. The processing conditions such as the center interval α of the laser processing grooves (the first laser processing groove 95a and the second laser processing groove 95b) are adjusted, and appropriate processing conditions are set. The machining conditions set in this way are stored in a random access memory (RAM) 83 of the control means 8. Then, by performing the above-described laser processing groove forming step according to the set processing conditions, two laser processing grooves can be reliably formed in a predetermined region along the street 93 of the semiconductor wafer 9. When cutting the semiconductor wafer 9 along the street 93 by positioning a cutting blade between the two laser processing grooves, a laser is inserted between the two laser processing grooves to improve the guide of the cutting blade. A processing groove may be formed.

The perspective view of the laser processing apparatus for enforcing the processing condition setting method of the wafer by this invention The block diagram which shows simply the structure of the laser beam irradiation means with which the laser processing apparatus shown in FIG. 1 is equipped. The perspective view which shows the semiconductor wafer as a wafer used for the processing condition setting method of the wafer by this invention. FIG. 4 is an enlarged cross-sectional view of the semiconductor wafer shown in FIG. 3. FIG. 4 is a perspective view showing a state in which the semiconductor wafer shown in FIG. 3 is supported on an annular frame via a protective tape. Explanatory drawing of the street detection process in the processing condition setting method of the wafer by this invention. Explanatory drawing of the center space | interval setting process in the processing condition setting method of the wafer by this invention. Explanatory drawing of the laser processing groove | channel formation process in the processing condition setting method of the wafer by this invention. Explanatory drawing of the inner space | interval measurement process in the processing condition setting method of the wafer by this invention. Explanatory drawing of the outer space | interval calculation process in the processing condition setting method of the wafer by this invention. The cross-sectional enlarged view of the wafer in which the laser processing groove | channel formation process in the processing condition setting method of the wafer by this invention was implemented. Explanatory drawing which shows the relationship between the 2 laser processing groove | channel formed by the laser processing groove | channel formation process in the processing condition setting method of the wafer by this invention, and a cutting blade.

Explanation of symbols

1: laser processing device 2: stationary base 3: chuck table mechanism 36: chuck table 37: processing feed means 38: first index feed means 4: laser beam irradiation unit support mechanism 43: second index feed means 5: laser beam Irradiation unit 52: Laser beam irradiation means 6: Imaging means 8: Control means 9: Semiconductor wafer 90: Semiconductor substrate 91: Laminate 92: Device 93: Street 94: Resin coating 95a: First laser processing groove 95b: Second Laser processing groove

Claims (1)

A chuck table for holding a wafer, a laser beam irradiation means for irradiating a wafer held on the chuck table with a laser beam, a machining feed means for moving the chuck table and the laser beam irradiation means in a machining feed direction, Laser processing apparatus comprising: index feeding means for relatively moving the chuck table and the laser beam irradiating means in an index feeding direction orthogonal to the machining feed direction; and an imaging means for imaging the wafer held on the chuck table To set processing conditions for forming two laser processing grooves along the streets of a wafer in which devices are formed in a plurality of regions partitioned by a plurality of streets formed in a lattice pattern on the surface The processing condition setting method of
A street detection step of imaging the street formed on the wafer held on the chuck table by the imaging means and detecting the center of the street;
A center interval setting step for setting the center interval of the two laser processing grooves to be formed on both sides of the center of the street detected by the street detection step;
A processing groove forming step of operating the laser beam irradiation means, the processing feeding means, and the indexing feeding means to form two laser processing grooves at the center interval set by the center interval setting step on both sides of the center of the street;
An inner interval measuring step in which the processed groove forming step is performed and the street is imaged by the imaging means, and an inner interval between the two laser processed grooves formed in the street is measured;
When the center interval of the two laser processing grooves set in the center interval setting step is α and the inner interval of the two laser processing grooves measured in the inner interval measurement step is β, two laser processing An outer interval calculating step of obtaining an outer interval γ of the groove by γ = 2α−β,
A method for setting processing conditions for a wafer.

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