JP2016163016A - Manufacturing method of device chip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a device chip capable of continuously arranging a plurality of devices side by side in one line without a gap.SOLUTION: The manufacturing method includes: a modified layer formation step for forming a plurality of two lines of modified layers 21 that are in parallel with each other, in a vertical direction by positioning a convergence point P of a laser beam of a wavelength having transmissivity with respect to a semiconductor wafer 11 within the semiconductor wafer and radiating the laser beam from a rear face of the semiconductor wafer along both edges of a predetermined dividing line 13a in a width direction; and a division step for dividing the semiconductor wafer into a plurality of device chips with the modified layer as a fracture starting point by applying an external force to the semiconductor wafer after the modified layer formation step is implemented. In the modified layer formation step, the rear-side modified layer is formed at a position displaced from the front-side modified layer closer to a device 15, and a side face of the device chips fractured along the plurality of modified layers protrudes most at the front side.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a device chip manufacturing method used for a long line sensor, an LED printer head, or the like.

  Electronic components using device chips obtained by dividing device wafers such as semiconductor wafers and optical device wafers include electronic components such as long line sensors and LED printer heads.

  As a feature of these electronic components, the manufactured device bus chips are arranged in a line without gaps, and the distance between the device chips is reduced to the limit, thereby forming an electronic component in which a plurality of devices are aligned.

  In order to prevent missing of sensing or printing, etc., it is important to arrange the devices as continuously as possible without gaps. Therefore, when manufacturing the device chip, the device chip should not be left as much as possible with the planned division line of the device wafer. It is important to divide into

  In addition, when chips are arranged in a row, it is also important to manufacture so that no protrusions remain on the side surfaces of the chips so that there is no gap between adjacent devices. There has been proposed a machining method in which both edges in the width direction of a division-scheduled line are cut at different angles with a cutting blade inclined in a slanting direction (see, for example, JP 2010-073821 A or JP 2007-273743 A).

JP 2010-073821 A JP 2007-273743 A

  However, in the conventional method using a cutting blade, the cost of preparing a dedicated cutting device in which the cutting blade is inclined is required, and chipping occurs, so that the chipping does not proceed to the device. It is necessary to provide a margin for the distance from the cutting blade, and there is a limit to arranging a plurality of devices in a row continuously.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a device chip manufacturing method capable of arranging a plurality of devices in a row continuously without a gap. is there.

  According to the present invention, there is provided a device chip manufacturing method for manufacturing a device chip from a device wafer in which a device is formed in each region of a surface defined by a plurality of division lines having a predetermined width intersecting each other, A holding step for holding the device wafer with the front side of the wafer facing the holding surface of the chuck table, and after performing the holding step, a condensing point of a laser beam having a wavelength that is transmissive to the device wafer Positioned inside the wafer, the laser beam is irradiated from the back surface of the device wafer along both edges in the width direction of the planned dividing line to form a plurality of parallel modified layers in the vertical direction. After performing the quality layer forming step and the modified layer forming step, external force is applied to the device wafer, and the modified layer is formed. Dividing the device wafer into a plurality of device chips at the starting point of breakage, and in the modified layer forming step, a position where the modified layer on the back surface side is shifted to the device side from the modified layer on the front surface side The device chip manufacturing method is characterized in that the side surface of the device chip formed in the above-described manner and broken along the plurality of modified layers has the surface side most protruding.

  According to the device chip manufacturing method of the present invention, a plurality of modified layers are formed inside a device wafer with a laser beam to break the device wafer into individual device chips. The modified layer is formed closer to the center from both edges of the planned dividing line on the front surface side, and the modified layer is formed along both edges on the back surface side.

  Therefore, in the device chip obtained by dividing the device wafer, since the side surface of the chip is inclined obliquely downward (chip center side) from the surface, a gap is formed between adjacent chips on the device surface side when the chips are connected. There is nothing to do. Therefore, when a plurality of device chips are arranged in one row, the plurality of device chips can be arranged in one row with almost no gap between adjacent devices.

  In addition, since the modified layer formed on the device wafer is divided into a plurality of device chips from the starting point of breakage, there is no chipping, and there is an effect that the device chip can be broken at a portion as close as possible to the edge of the planned dividing line. .

It is a surface side perspective view of a semiconductor wafer. It is a perspective view of the state where the surface side of a semiconductor wafer was stuck on the expanded tape as an adhesive tape with an outer peripheral part attached to an annular frame. It is a partial cross section side view explaining a modified layer formation step. It is a partial enlarged view of the back surface side of the semiconductor wafer explaining the position where the modified layer is formed in the modified layer forming step. FIG. 5A is a sectional view showing the modified layer forming method of the first embodiment of the present invention, and FIG. 5B is a sectional view showing the modified layer forming method of the second embodiment. 6 (A) and 6 (B) are partial cross-sectional side views showing the dividing step, and FIG. 6 (C) is an enlarged view of a portion A in FIG. 6 (B). It is sectional drawing of the line sensor which arranged the several device chip in 1 row.

  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 (device wafer) is shown. A device wafer 11 shown in FIG. 1 is made of, for example, a silicon wafer having a thickness of 300 μm, and a plurality of division lines (streets) 13 are formed in a lattice shape on the surface 11a, and a plurality of division lines 13 are formed. A device 15 such as a CCD or a CMOS is formed in each region partitioned by.

  The semiconductor wafer 11 configured as described above includes a device region 17 in which a plurality of devices 15 are formed and an outer peripheral surplus region 19 surrounding the device region 17 on its surface 11a. 11 b is the back surface of the semiconductor wafer 11.

  The wafer to be processed by the device chip manufacturing method of the present invention is not limited to the semiconductor wafer 11 as shown in FIG. 1, but an epitaxial layer (light emitting layer) such as gallium nitride is formed on a sapphire substrate. A device wafer such as an optical device wafer is also included.

  In the device chip manufacturing method according to the embodiment of the present invention, prior to processing, as shown in FIG. 2, the surface 11a of the device wafer 11 is pasted on an expanded tape T made of an adhesive tape having an outer peripheral portion attached to an annular frame F. To wear. Therefore, the back surface 11b of the device wafer 11 is exposed during processing.

  In the device chip manufacturing method of the present embodiment, first, a holding step of holding the device wafer 11 with the surface 11a side of the device wafer 11 facing the holding surface of the chuck table of the laser processing apparatus is performed.

  That is, as shown in FIG. 3, the device wafer 11 is sucked and held via the expanded tape T by the chuck table 10 of the laser processing apparatus, and the back surface 11b side of the device wafer 11 is exposed upward. Then, the annular frame F is clamped and fixed by the clamp 12.

  With the device wafer 11 held by the chuck table 10, the condensing point of the pulsed laser beam having a wavelength (for example, 1064 nm) having transparency to the device wafer 11 by the concentrator 14 of the laser beam generating unit is scheduled to be divided. The laser beam is irradiated from the back surface 11b side of the wafer 11 and the chuck table 10 is processed and sent in the arrow X1 direction or the X2 direction so that the modified layer 21 is formed inside the wafer. A modified layer forming step for forming a plurality of layers is performed.

  The position of the modified layer formed in this modified layer forming step will be described with reference to FIG. In FIG. 4, description will be made assuming that the side division planned line where devices need to be arranged closely is 13 a and the side division planned line where devices do not need to be arranged closely is 13 b.

  In the planned dividing line 13a, two modified layers 21 are formed inside the wafer 11 along both edges in the width direction of the planned dividing line 13a. The modification layer 21 in this direction is formed in a plurality of layers in the thickness direction of the wafer 11.

  For the planned division line 13b, one modified layer 21 is formed inside the wafer along the approximate center of the planned division line 13b. The modified layer 21 in this direction is also formed in a plurality of layers in the thickness direction of the wafer 11.

  With reference to FIG. 5, the modified layer forming step will be described in more detail. FIG. 5A is a cross-sectional view showing a modified layer forming step of the first embodiment. In the modified layer forming step of the first embodiment, two parallel modified layers are first placed on the side close to the surface 11a of the device wafer 11 at a position on the center side of the predetermined distance from both edges of the division line 13a. 21 is formed.

  Next, two modified layers parallel to each other along both edges of the planned dividing line 13a at a position where the condensing point P of the laser beam condensed by the condenser 14 is raised to the back surface 11b side of the wafer 11. 21 is formed. Further, the condensing point P of the laser beam is positioned on the back surface 11b side of the wafer 11, and the two modified layers 21 parallel to each other are formed so as to overlap the modified layer 21 formed immediately before. By indexing and feeding the wafer 11, a plurality of similar two modified layers 21 are formed along the adjacent division line 13a.

  In the embodiment shown in FIG. 5A, one modified layer 21 on the side close to the front surface 11a of the wafer 11 is formed, and two modified layers 21 on the back surface 11b side that overlap in the vertical direction are formed. However, the number of the modified layers 21 is not limited to this, and two or more modified layers 21 on the front surface 11a side may be formed, and one modified layer 21 on the back surface 11b side may be formed. Only three layers or more may be formed.

  Since the planned dividing line 13b is on the side where it is not necessary to arrange the devices densely, a plurality of modified layers 21 are formed so as to overlap in the vertical direction along the center of the planned dividing line 13b.

  Referring to FIG. 5B, a cross-sectional view showing a modified layer forming step of the second embodiment of the present invention is shown. In the modified layer forming step of the present embodiment, the modified layer 21 on the surface 11 a side of the wafer 11 and the modified layer 21 to be formed next are formed so as to overlap in the thickness direction of the wafer 11.

  The overlap length is preferably about 30 μm. It was confirmed that desired cracks propagated from the modified layer 21 can be reliably formed by forming the modified layer 21 in an overlapping manner.

  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
Average output: 0.2W
Repetition frequency: 80 kHz
Condensing spot diameter: φ1μm
Processing feed rate: 100 nm / s

  After performing the modified layer forming step, an external force is applied to the device wafer 11, and a dividing step is performed in which the modified wafer 21 is divided into a plurality of device chips with the modified layer 21 as a starting point of breakage.

  This division step will be described with reference to FIG. Referring to FIG. 6A, the dividing device 20 includes an expansion drum 22 and a frame holding unit 24 that holds the annular frame F. The expansion drum 22 has an inner diameter smaller than the inner diameter of the annular frame F and larger than the outer diameter of the wafer 11 attached to the expanded tape T attached to the annular frame F.

  The frame holding means 24 includes an annular frame holding member 26 and a plurality of clamps 28 as fixing means arranged on the outer periphery of the frame holding member 26. An upper surface of the frame holding member 26 forms a mounting surface 26a on which the annular frame F is mounted. The annular frame F is mounted on the mounting surface 26a.

  The annular frame F placed on the placement surface 26 a is fixed to the frame holding member 26 by the clamp 28. The frame holding means 24 configured as described above is connected to the piston rod 32 of the air cylinder 30, and the frame holding member 26 is moved in the vertical direction by operating the air cylinder 30.

  A wafer dividing step performed using the dividing apparatus 20 configured as described above will be described with reference to FIGS. 6 (A) to 6 (C). As shown in FIG. 6A, the annular frame F that supports the wafer 11 via the expanded tape T is placed on the placement surface 26 a of the frame holding member 26 and fixed to the frame holding member 26 by the clamp 28. To do. At this time, the frame holding member 26 is positioned at a reference position where the mounting surface 26 a is substantially the same height as the upper end of the expansion drum 22.

  Next, the air cylinder 30 is driven to lower the frame holding member 26 to the extended position shown in FIG. As a result, the annular frame F fixed on the mounting surface 26a of the frame holding member 26 is also lowered, so that the expanded tape T attached to the annular frame F abuts on the upper edge of the expansion drum 22 and mainly has a radius. Expanded in the direction.

  As a result, a tensile force acts radially on the wafer 11 adhered to the expanded tape T. Thus, when a radial pulling force acts on the wafer 11, the wafer 11 is broken with the modified layer 21 as a starting point and is divided into individual device chips 23.

  In the device chip manufacturing method according to the present embodiment, the two reformed layers 21 are formed at the same height along the division lines 13a on the side division lines 13a on which the devices need to be arranged closely. Thus, a plurality of modified layers 21 are formed in the thickness direction of the wafer 11.

  Further, since the pair of modified layers 21 closer to the back surface side than the pair of modified layers 21 closest to the front surface 11a side of the wafer 11 are formed on the side closer to the device 15, A in FIG. As shown in FIG. 6C, which is an enlarged view of the portion, the side surface of the device chip 23 obtained by dividing the wafer 11 is inclined obliquely from the surface on which the device 15 is formed to the chip center side. Further, the street portion 25 remains between the adjacent device chips 23.

  Although not particularly illustrated, for the planned division line 13b orthogonal to the planned division line 13a extending in the first direction, as shown in FIG. 4, one modified layer 21 is provided at the substantially central portion of the planned division line 13b. Therefore, when the dividing step shown in FIG. 6 is performed, the side surface of each device chip 23 is perpendicular to the device 15 formed on the surface.

  According to the device chip manufacturing method of the above-described embodiment, a plurality of device chips 23 are connected to the side where the devices need to be arranged closely because the side surface of the chip is inclined obliquely from the surface to the chip center side. For example, when the line sensor 27 as shown in FIG. 7 is configured, the device chips 23 can be aligned so that there is almost no gap between the adjacent devices 15.

  In the above-described embodiment, the example in which the device chip of the present invention is applied to a semiconductor wafer to manufacture an imaging device chip such as a CCD or CMOS has been described. However, the manufacturing method of the present invention is not limited to this, The present invention can be applied to a method of manufacturing an LED chip by applying it to the division of an optical device wafer having a plurality of LEDs formed on the surface.

10 Chuck table 11 Semiconductor wafers 13, 13a, 13b Scheduled division line (street)
14 Condenser 15 Device 20 Dividing Device 21 Modified Layer 22 Expansion Drum 23 Device Chip 24 Frame Holding Unit 25 Street Part 26 Frame Holding Member 27 Line Sensor

Claims (1)

A device chip manufacturing method for manufacturing a device chip from a device wafer in which a device is formed in each region of a surface defined by a plurality of division lines having a predetermined width intersecting each other,
A holding step of holding the device wafer with the front side of the device wafer facing the holding surface of the chuck table;
After performing the holding step, a condensing point of a laser beam having a wavelength that is transmissive to the device wafer is positioned inside the device wafer, and the laser beam is directed from the back surface of the device wafer in the width direction of the division line. A modified layer forming step of irradiating along both edges and forming a plurality of parallel modified layers of the two strips in the vertical direction;
A step of dividing the device wafer into a plurality of device chips by applying an external force to the device wafer after performing the modified layer forming step,
In the modified layer forming step, the modified layer on the back side is formed at a position shifted to the device side from the modified layer on the front side,
The device chip manufacturing method, wherein the side surface of the device chip that is broken along the plurality of modified layers has a surface side that protrudes most.

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