JP6029312B2 - Processing method of plate - Google Patents

Description

  The present invention relates to a processing method for a plate-like object such as a wafer in which a plurality of division lines that intersect the surface are set.

  A plate-like object such as a semiconductor wafer is cut along a division line by a cutting device and divided into individual chips. Alternatively, after a laser processing groove and a modified layer are formed along a division line by a laser processing apparatus, an external force is applied and the chip is divided into individual chips.

  Along with processing and division by a cutting device or a laser processing device, processing waste and division waste of a plate-like object are generated. Therefore, for example, the processed or divided plate-like material is washed with a cleaning device as disclosed in JP 2000-033346 A to wash away the machining waste and divided waste. Washing water jetted at a high pressure or a mixed fluid of a liquid and a high-pressure gas is widely used for cleaning a plate-like object after processing or division.

JP 2000-033346 A

  However, the distance between the chips after cutting or dividing is very narrow, and even if the plate-like object is cleaned with a cleaning device, it is very possible to clean the space between the chips and remove foreign matters such as processing scraps and split scraps. difficult.

  If foreign matter remains between the chips, the foreign matter may contaminate the inside of the processing apparatus or the transport mechanism during subsequent processes or handling. Further, in a chip on which a device or an electrode is formed, there is a risk that a foreign substance adheres to cause a device failure or a bonding failure in a subsequent bonding process.

  The present invention has been made in view of the above points, and the object of the present invention is to reduce the possibility of contamination of a processing apparatus, a transport mechanism, and the like by foreign matters adhering to a plate-like object, It is an object of the present invention to provide a plate-like material processing method capable of reducing the risk of causing a defect in a subsequent process.

According to the present invention, there is provided a processing method for a plate-like object in which a plurality of intersecting scheduled lines are set, and the plate-like object is divided along the scheduled division lines by applying a tensile force radially to the plate-like object. And, after performing the dividing step, the gel-like adsorbing member is pressed from the upper surface of the divided plate-like material to enter between the plurality of chips, and at least foreign matter between the chips A foreign matter adsorbing step for adsorbing the gel-like adsorbing member, and after the foreign matter adsorbing step, the foreign matter adhering to the plate-like object is removed by removing the gel-like adsorbing member from the plate-like object. And a removing step. A method of processing a plate-like object is provided.

  According to the present invention, the gel-like adsorbing member is pressed into the divided plate-like object to cause the gel-like adsorbing member to enter the gap between the chips, and the foreign matter is adsorbed to the gel-like adsorbing member to adhere to the plate-like object. Remove the foreign material. Since it is possible to remove foreign matter more reliably than foreign matter removal using a fluid, foreign matter can be removed in a shorter time.

  In addition, the processing method of the present invention eliminates the need for cleaning with a liquid, and thus is particularly suitable for removing foreign matter from a plate-like object that is difficult to clean with a liquid, such as ceramics before sintering.

It is a perspective view of the wafer supported by the annular frame via the dicing tape. It is a perspective view which shows a mode that the wafer is cut with the cutting device. It is a perspective view which shows a mode that the modified layer is formed in the inside of a wafer with the laser processing apparatus. It is sectional drawing which shows a division | segmentation step. It is sectional drawing which shows a foreign material adsorption | suction step (the 1). It is sectional drawing which shows a foreign material adsorption | suction step (the 2). It is sectional drawing which shows a removal step.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Referring to FIG. 1, a perspective view of a semiconductor wafer (hereinafter abbreviated as “wafer”) 11 which is a kind of plate-like object supported by an annular frame F via a dicing tape T is shown.

  On the surface of the wafer 11, devices 15 such as ICs and LSIs are formed in each region partitioned by a plurality of division lines 13 formed in a lattice shape. Prior to cutting or laser processing of the wafer 11, the wafer 11 is attached to a dicing tape T having an outer peripheral portion attached to the annular frame F.

  The plate-like object to be processed of the present invention includes various ceramics, metal plates, and package substrates on which devices such as the semiconductor wafer 11 and the optical device wafer shown in FIG. Including a chip capacitor.

  Next, with reference to FIG. 2, the division | segmentation step using the cutting device 2 is demonstrated. The wafer 11 is sucked and held via the dicing tape T by the chuck table 4 of the cutting device 2.

  A cutting unit 6 of the cutting apparatus 2 includes a spindle that is rotationally driven by a motor (not shown) housed in a spindle housing 8 and a cutting blade 10 that is detachably attached to the tip of the spindle.

  The cutting blade 10 is covered with a wheel cover 12, and a pipe 14 of the wheel cover 12 is connected to a cutting water supply source that supplies pure water or the like. The cutting blade 10 is configured by electrodepositing a grindstone portion (cutting blade) in which diamond abrasive grains are dispersed in a nickel base material or a nickel alloy base material on the outer periphery of a circular base.

  When cutting the wafer 11, the cutting blade 10 is rotated at high speed (for example, 30000 rpm) in the direction of arrow A while jetting cutting water from the cutting water nozzle 16 disposed so as to sandwich the cutting blade 10, and the chuck table 4 is moved. By processing and feeding in the X-axis direction, the wafer 11 is cut along the planned dividing line 13 to form the divided grooves 18.

  While indexing and feeding the chuck table 4 in the Y-axis direction, the division grooves 18 are formed along all the division lines 13 extending in the first direction. Next, after the chuck table 4 is rotated by 90 degrees, a similar dividing groove 18 is formed along the planned dividing line 13 extending in the second direction orthogonal to the first direction, and the wafer 11 is formed on each chip. To divide.

  Next, with reference to FIG. 3, the division | segmentation step using a laser processing apparatus is demonstrated. The wafer 11 is attached to the dicing tape T on the front surface side, and the back surface 11b is exposed and sucked and held by the chuck table 20 of the laser processing apparatus.

  The laser beam irradiation unit 22 has a cylindrical casing 26 arranged substantially horizontally. In the casing 26, a pulse laser beam oscillation unit including a pulse laser oscillator such as a YAG laser oscillator or a YVO4 laser oscillator and a repetition frequency setting unit is disposed. A condenser 28 that collects the pulse laser beam oscillated from the pulse laser beam oscillation unit is attached to the tip of the casing 26.

  Reference numeral 24 denotes an image pickup unit. In addition to a normal image pickup device (CCD) that picks up an image with visible light, an infrared irradiation unit that irradiates the wafer 11 with infrared rays, and an infrared image pickup device (infrared CCD) that outputs an electrical signal corresponding to the infrared rays. The captured image signal is transmitted to a controller (not shown).

  The chuck table 20 that sucks and holds the wafer 11 is positioned directly below the imaging unit 24 by a moving mechanism (not shown). Then, alignment for detecting a processing region of the wafer 11 to be laser processed by the imaging unit 24 is performed.

  That is, the imaging unit 24 and a controller (not shown) are for aligning the planned dividing line 13 extending in the first direction of the wafer 11 and the condenser 28 that irradiates the laser beam along the planned dividing line 13. Image processing such as pattern matching is executed to align the laser beam irradiation position.

  Next, alignment of the laser beam irradiation position is similarly performed on the division line 13 extending in the direction orthogonal to the first direction formed on the wafer 11. At this time, the front surface 11a on which the division lines 13 of the wafer 11 are formed is positioned on the lower side, but since the imaging unit 24 includes an infrared CCD, the division lines 13 are watermarked from the back surface 11b side. An image can be taken.

  After the alignment is performed, the chuck table 20 is moved in the X-axis direction, and one end of the planned dividing line 13 extending in the first direction is positioned directly below the condenser 38 of the laser beam irradiation unit 22.

  Then, while the condensing point of the pulse laser beam having transparency to the wafer 11 from the condenser 28 is positioned inside the wafer 11 and irradiated with the pulse laser beam, the chuck table 20 is moved in the arrow X direction in FIG. By moving at a predetermined processing feed rate, the modified layer 29 is formed along the scheduled division line 13 inside the wafer 11. This modified layer is formed as a melt rehardened layer. The modified layer refers to a region where the density, refractive index, mechanical strength, and other physical characteristics are different from the surroundings.

  The processing conditions in the modified layer forming step are set as follows, for example.

Light source: LD excitation Q switch Nd: YVO 4 pulse laser Wavelength: 1064 nm
Repetition frequency: 100 kHz
Pulse output: 10μJ
Processing feed rate: 100 mm / sec

  After the modified layer forming step is performed along all the division lines 13 extending in the first direction, the chuck table 20 is rotated by 90 degrees and then extended in the second direction orthogonal to the first direction. The same modified layer forming step is performed along all the division lines 13 to be performed.

  Instead of forming the modified layer 29 inside the wafer 11, a laser processing groove may be formed along the planned division line 13 of the wafer 11 by ablation. In this case, the back surface 11b side of the wafer 11 is adhered to the dicing tape T, and the wafer 11 is sucked and held by the chuck table 20 with the front surface 11a side of the wafer 11 exposed.

  Then, a laser beam having a wavelength (for example, 355 nm) having an absorptivity with respect to the wafer 11 is irradiated along the division line 13 to form a laser processing groove by ablation processing.

  While indexing and feeding the chuck table 20, similar laser processing grooves are formed by ablation along all the division lines 13 extending in the first direction. Next, after the chuck table 20 is rotated by 90 degrees, similar laser processing grooves are formed by ablation along all the planned division lines 13 extending in the second direction orthogonal to the first direction.

  After performing the modified layer forming step or the laser processing groove forming step, the dividing step of dividing the wafer 11 by the dividing device 30 as shown in FIG.

  4A, the dividing device 30 includes a frame holding unit 32 that holds the annular frame F, and an expansion drum 34 that extends the dicing tape T attached to the annular frame F held by the frame holding unit 32. ing.

  The frame holding unit 30 includes an annular frame holding member 36 and a plurality of clamps 38 as fixing means disposed on the outer periphery of the frame holding member 36. An upper surface of the frame holding member 36 forms a mounting surface 36a on which the annular frame F is placed, and the annular frame F is placed on the mounting surface 36a.

  The frame holding unit 32 is driven by a driving means 40 including an air cylinder 42, and the annular frame holding member 36 is placed at a reference position where the mounting surface 36 a is substantially flush with the upper end of the expansion drum 34, and the expansion drum 34. It moves in the vertical direction between the extended positions below the upper end by a predetermined amount. A piston rod 44 of the air cylinder 42 is connected to the lower surface of the frame holding member 36.

  In the dividing step, as shown in FIG. 4A, the annular frame F that supports the wafer 11 via the dicing tape T is placed on the placement surface 36a of the frame holding member 36, and the frame is held by the clamp 38. The member 36 is fixed. At this time, the frame holding member 36 is positioned at a reference position where the placement surface 36 a is substantially the same height as the upper end of the expansion drum 34.

  Next, the air cylinder 42 is driven to lower the frame holding member 36 to the extended position shown in FIG. As a result, the annular frame F fixed on the mounting surface 36a of the frame holding member 36 is also lowered, so that the dicing tape T attached to the annular frame F abuts on the upper end edge of the expansion drum 34 and mainly has a radius. Expanded in the direction.

  As a result, radial tensile forces act on the wafer 11 adhered to the dicing tape T. When a tensile force is applied to the wafer 11 in a radial manner in this manner, the strength of the modified layer 29 formed inside the wafer along the scheduled division line 13 is reduced, so that the modified layer 29 or the laser processing groove is divided. As a starting point, the wafer 11 is broken along the modified layer 29 or the laser processing groove and divided into individual chips 17.

  When the dividing step using the cutting device or the laser processing device is performed, cutting waste and processing waste are generated, and the foreign material 21 of the cutting waste and processing waste adheres to the wafer 11 and remains as shown in FIG.

  Therefore, in the processing method of the present invention, the gel-like adsorbing member 50 is pressed against the wafer 11 as shown by the arrow A from the upper surface of the divided wafer 11, and the gel-like adsorbing member 50 is moved as shown in FIG. The foreign substance 21 is adsorbed by the gel-like adsorbing member 50 by entering the gap between the adjacent chips 17. The pressing of the gel-like adsorption member 50 is manually pressed by a press or an operator.

  The gel-like adsorbing member 50 is made of, for example, benzalkonium chloride, methyl paraben, propyl paraben, ethanol, boric acid, diazolinyl urea, or the like.

  After the gel-like adsorbing member 50 is sufficiently pressed against the wafer 11, a removal step of removing the gel-like adsorbing member 50 from the wafer 11 is performed as shown in FIG. When this removal step is performed, the foreign matter 21 attached to the wafer 11, particularly the foreign matter 21 attached to the gap between the chips 17, can be attached to the gel-like adsorbing member 50 and removed.

DESCRIPTION OF SYMBOLS 10 Cutting blade 11 Semiconductor wafer 13 Scheduled dividing line 15 Device 17 Chip 21 Foreign material 22 Laser beam irradiation unit 28 Condenser 29 Modified layer 30 Dividing apparatus 50 Gel-like adsorption member

Claims (1)

A processing method for a plate-like object in which a plurality of intersecting division lines are set,
A dividing step in which a tensile force is applied radially to the plate-like object to divide the plate-like object along the planned dividing line, thereby forming a plurality of chips;
After performing the dividing step, the foreign substance adsorption step of pressing the gel-like adsorbing member from the upper surface of the divided plate-like object to enter between the plurality of chips, and adsorbing at least foreign substances between the chips to the gel-like adsorbing member When,
After performing the foreign matter adsorption step, a removal step of removing the foreign matter attached to the plate-like object by removing the gel-like adsorbing member from the plate-like object,
A method for processing a plate-like object comprising:

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