Chip manufacturing method

Abstract

To provide a chip manufacturing method with which it is possible to prevent breakage of a device when removing a ring-shaped reinforcement part and improve the productivity of chips manufactured from a wafer.SOLUTION: Prior to a removal step in which a ring-shaped reinforcement part is removed, a singulation step for singulating a plurality of devices and manufacturing chips is carried out. So the removal step is carried out while the ring-shaped reinforcement part and the plurality of device chips are separated, making it possible to prevent the devices from being broken by the force applied to the ring-shaped reinforcement part in the removal step. Furthermore, there is no step of separating the device region of a wafer and the ring-shaped reinforcement part, and it is possible to manufacture a plurality of device chips while at the same time removing the ring-shaped reinforcement part. Thus, as compared with a chip manufacturing method that includes said step, chip productivity can be improved.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing chips from a wafer in which a device region in which multiple devices are formed is thinned and a central region of a tape in which the peripheral region is attached to an annular frame is attached to the back surface of the wafer, which has a recess formed thereon so as to leave the peripheral excess region surrounding the device region as a ring-shaped reinforcing portion. [Background technology]

[0002] Chips for devices such as integrated circuits (ICs) are essential components in various electronic devices such as mobile phones and personal computers. Such chips are manufactured, for example, by dividing a wafer having a device region on the front side where multiple devices are formed and a peripheral excess region surrounding the device region along the boundaries of the multiple devices, i.e., by singulating the multiple devices.

[0003] The wafer may be thinned before being divided in order to reduce the size of the chips to be manufactured. For example, a method for thinning the wafer may involve grinding using a holding table that holds the wafer and a grinding wheel that is provided above the holding table and has a plurality of grinding stones that are arranged discretely in an annular shape. This grinding is generally performed in the following order:

[0004] First, the wafer is held on a holding table so that the backside is exposed. Next, the holding table is moved so that the center of the backside of the wafer is positioned directly under the path of the multiple grinding wheels when the grinding wheel is rotated. Next, while both the grinding wheel and the holding table are rotated, the grinding wheel is lowered so that the multiple grinding wheels come into contact with the backside of the wafer. This grinds the backside of the wafer, thinning the wafer.

[0005] However, as the wafer becomes thinner, its rigidity decreases, making it more susceptible to cracking. Therefore, a method has been proposed in which a recess is formed on the backside of the wafer so that the device region of the wafer is thinned and the peripheral excess region remains as a ring-shaped reinforcement. In this method, a recess is formed on the backside of the wafer by grinding the backside of the wafer as described above using a grinding wheel with an outer diameter shorter than the radius of the wafer.

[0006] Furthermore, since the ring-shaped reinforcement portion is no longer necessary when manufacturing chips from this wafer, the ring-shaped reinforcement portion may be removed by grinding prior to singulating the wafer into multiple devices. However, grinding the ring-shaped reinforcement portion may cause the device region connected to the ring-shaped reinforcement portion to chip due to the force applied by the grinding, or may cause cracks to propagate into the device region, damaging the devices included in the device region.

[0007] In light of this, it has been proposed to separate the device region and the ring-shaped reinforcing portion by dividing the wafer along the periphery of the device region before removing the ring-shaped reinforcing portion by grinding (see, for example, Patent Document 1). This makes it possible to prevent damage to the devices included in the device region. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent Publication No. 2021-72353 Summary of the Invention [Problem to be solved by the invention]

[0009] However, when dividing a wafer along the periphery of the thinned device region, the force applied by the division may damage the devices contained in the device region, so the division must be performed slowly to avoid adversely affecting the device region, resulting in low yields of chips manufactured from the wafer.

[0010] In view of this, an object of the present invention is to provide a chip manufacturing method that can prevent damage to the device when removing the ring-shaped reinforcing portion and improve the productivity of chips manufactured from wafers. [Means for solving the problem]

[0011] According to the present invention, a method for manufacturing chips from a wafer in which a device region in which a plurality of devices are formed is thinned and a central region of a tape, with the peripheral region attached to an annular frame, is attached to a back surface on which a recess is formed so as to leave a peripheral excess region surrounding the device region as a ring-shaped reinforcing portion, the method comprising: a singulation step for manufacturing chips by processing the wafer along the boundaries of the plurality of devices to individualize the plurality of devices; and a removal step for removing the ring-shaped reinforcing portion using a rotating cutting blade after the singulation step. The method does not include a step of separating the device region and the ring-shaped reinforcement portion by dividing the wafer along the periphery of the device region. A method for manufacturing the chip is provided.

[0012] Preferably, in the singulation step, the plurality of devices are singulated using a rotating singulation cutting blade or a laser beam of a wavelength absorbed by the wafer. [Effects of the Invention]

[0013] In the present invention, a singulation step of singulating the plurality of devices to manufacture chips is performed prior to the removal step of removing the ring-shaped reinforcing portion. That is, in the present invention, the removal step is performed in a state in which the ring-shaped reinforcing portion and the chips of the plurality of devices are separated. Therefore, in the present invention, damage to the devices due to the force applied to the ring-shaped reinforcing portion in the removal step can be prevented.

[0014] Furthermore, in the present invention, the ring-shaped reinforcing portion can be removed and chips of multiple devices can be manufactured without performing a step of separating the device region of the wafer from the ring-shaped reinforcing portion, which makes it possible to improve chip productivity compared to chip manufacturing methods that include this step. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1(A) is a perspective view that schematically shows an example of a frame unit that includes a wafer, and FIG. 1(B) is a cross-sectional view that schematically shows the frame unit shown in FIG. 1(A). [Figure 2] FIG. 2 is a flow chart schematically showing an example of a method for manufacturing chips from a wafer included in a frame unit. [Figure 3] FIG. 3(A) is a partial cross-sectional side view schematically showing an example of the singulation step, and FIG. 3(B) is a partial cross-sectional side view schematically showing another example of the singulation step. [Figure 4] 4(A), 4(B), and 4(C) are each a partial cross-sectional side view schematically showing an example of the removing step. [Figure 5] 5(A) and 5(B) are each a partial cross-sectional side view schematically showing another example of the removing step. DETAILED DESCRIPTION OF THE INVENTION

[0016] An embodiment of the present invention will be described with reference to the accompanying drawings. Fig. 1(A) is a perspective view showing an example of a frame unit including a wafer, and Fig. 1(B) is a cross-sectional view showing the frame unit shown in Fig. 1(A). The frame unit 11 shown in Fig. 1(A) and Fig. 1(B) has a wafer 13 with an exposed surface 13a.

[0017] The wafer 13 is made of a single-crystal semiconductor material such as silicon (Si), silicon carbide (SiC), or gallium nitride (GaN), and further has a device region 13b in which a plurality of devices 15 are formed, and a peripheral excess region 13c surrounding the device region 13b.

[0018] In the device region 13b, the boundaries of the multiple devices 15 are set in a grid pattern, and each of the multiple straight line portions included in the boundaries is also called a dividing line. In addition, a recess 13e is formed on the back surface 13d of the wafer 13 so as to thin the device region 13b and leave the peripheral excess region 13c as a ring-shaped reinforcing portion 14.

[0019] Furthermore, a central region of a disk-shaped tape 17 having a diameter larger than that of the wafer 13 is attached to the back surface 13d of the wafer 13 so as to fit closely to the wafer 13 in the recess 13e without any gaps. The tape 17 has, for example, a flexible film-like tape base material and an adhesive layer (glue layer) provided on the wafer 13 side of the tape base material.

[0020] The tape substrate is made of polyolefin (PO), polyethylene terephthalate (PET), polyvinyl chloride (PVC), polystyrene (PS), etc. The adhesive layer is made of ultraviolet-curing silicone rubber, acrylic material, epoxy material, etc.

[0021] Additionally, an annular frame 19 having an inner diameter larger than the diameter of the wafer 13 is attached to the outer periphery of the tape 17. The annular frame 19 is made of a metal material such as aluminum or stainless steel.

[0022] 2 is a flowchart schematically illustrating an example of a method for manufacturing chips from the wafer 13 included in the frame unit 11. In this method, first, the wafer 13 is processed along the boundaries of the devices 15 to separate the devices 15 into individual chips (singulation step: S1).

[0023] Fig. 3(A) is a partial cross-sectional side view schematically illustrating an example of the singulation step (S1). Briefly, Fig. 3(A) illustrates how a cutting device singulates a plurality of devices 15 using a rotating cutting blade (singulation cutting blade).

[0024] Note that the X1 axis direction and the Y1 axis direction shown in FIG. 3(A) are directions that are perpendicular to each other on a horizontal plane, and the Z1 axis direction is a direction (vertical direction) that is perpendicular to both the X1 axis direction and the Y1 axis direction.

[0025] 3(A) includes a holding table 4. The holding table 4 has a disk-shaped frame 4a whose diameter is slightly smaller than the diameter of the recess 13e formed on the back surface 13d of the wafer 13.

[0026] The frame 4a is made of, for example, a metal material such as stainless steel or ceramics. The frame 4a has a disk-shaped bottom wall and a cylindrical side wall extending from the outer periphery of the bottom wall. That is, a disk-shaped recess defined by the bottom wall and the side wall is formed on the upper surface of the frame 4a.

[0027] A circular porous plate (not shown) having a diameter roughly equal to that of the recess formed on the upper surface of the frame 4a is fixed to the recess. This porous plate is made of, for example, porous ceramics.

[0028] The holding table 4 is also connected to an X1-axis direction movement mechanism (not shown). This X1-axis direction movement mechanism includes, for example, a ball screw and a motor. When this X1-axis direction movement mechanism is operated, the holding table 4 moves along the X1-axis direction.

[0029] The holding table 4 is also connected to a rotary drive source (not shown) such as a motor. When the rotary drive source is operated, the holding table 4 rotates around a rotation axis that passes through the center of the upper surface of the holding table 4 and is aligned with the Z1-axis direction.

[0030] The porous plate of the holding table 4 is connected to a suction source (not shown) such as an ejector through a through-hole formed in the bottom wall of the frame 4a. When the suction source is operated, a suction force acts on the space near the upper surface of the porous plate.

[0031] Furthermore, a plurality of clamps (not shown) are provided around the holding table 4 at approximately equal intervals along the circumferential direction of the holding table 4. Each of the plurality of clamps can grip the annular frame 19 included in the frame unit 11 and fasten the annular frame 19 at a position lower than the upper surface of the holding table 4.

[0032] Then, when the frame unit 11 is carried into the cutting device 2, the wafer 13 is placed on the holding table 4 via the tape 17 so that the recess 13e formed on the back surface 13d of the wafer 13 fits onto the upper part of the holding table 4.

[0033] At this time, the annular frame 19 of the frame unit 11 is gripped by multiple clamps and held at a position lower than the upper surface of the holding table 4. Furthermore, when a suction source communicating with the porous plate of the holding table 4 is operated in this state, the wafer 13 is held on the holding table 4 via the tape 17.

[0034] A cutting unit 6 is provided above the holding table 4. The cutting unit 6 includes a spindle 6a extending along the Y1 axis direction. A cutting blade 6b is attached to the tip of the spindle 6a.

[0035] The base end of the spindle 6a is connected to a rotary drive source (not shown) such as a motor. When the rotary drive source is operated, the cutting blade 6b rotates together with the spindle 6a around a straight line along the Y-axis direction as the rotation axis.

[0036] The cutting unit 6 is also connected to a Y1-axis direction moving mechanism (not shown) and a Z1-axis direction moving mechanism (not shown). Each of the Y1-axis direction moving mechanism and the Z1-axis direction moving mechanism includes, for example, a ball screw and a motor. When the Y1-axis direction moving mechanism and / or the Z1-axis direction moving mechanism is operated, the cutting unit 6 moves along the Y1-axis direction and / or the Z1-axis direction.

[0037] When performing the singulation step (S1) in the cutting device 2, first, a rotary drive source connected to the holding table 4 rotates the holding table 4 so that the linear portions (planned division lines) included in the boundaries of the multiple devices 15 formed on the wafer 13 are parallel to the X1 axis direction.

[0038] Next, the X1-axis direction moving mechanism adjusts the position of the holding table 4, and / or the Y1-axis direction moving mechanism adjusts the position of the cutting unit 6, so that the planned division line parallel to the X1-axis direction is positioned in the X1-axis direction when viewed in a plane from the cutting blade 6b.

[0039] Next, the Z1-axis movement mechanism raises and lowers the cutting unit 6 so that the lower end of the cutting blade 6b is positioned lower than the bottom surface of the recess 13e formed on the back surface 13d of the wafer 13 and higher than the upper surface of the holding table 4.

[0040] Next, the rotation drive source connected to the base end of the spindle 6a rotates the spindle 6a to rotate the cutting blade 6b. Next, the X1-axis direction moving mechanism moves the holding table 4 in the opposite direction of the X1-axis direction so that the lower end of the cutting blade 6b passes from one end of the wafer 13 to the other in the X1-axis direction. As a result, the wafer 13 is cut and divided along the planned division line.

[0041] In other words, grooves 11a that penetrate the wafer 13 and expose the tape 17 at the bottom are formed in the frame unit 11. Furthermore, the above-described process is repeated until the wafer 13 is divided at all of the boundaries of the multiple devices 15. This completes the singulation step (S1).

[0042] Note that specific examples of the singulation step (S1) are not limited to those described above. Fig. 3(B) is a partial cross-sectional side view schematically showing another example of the singulation step (S1). In short, Fig. 3(B) shows how a laser processing apparatus singulates a plurality of devices 15 using a laser beam having a wavelength that is absorbed by the wafer 13.

[0043] Note that the X2 axis direction and the Y2 axis direction shown in FIG. 3(B) are directions that are perpendicular to each other on a horizontal plane, and the Z2 axis direction is a direction (vertical direction) that is perpendicular to both the X2 axis direction and the Y2 axis direction.

[0044] The laser processing apparatus 8 shown in Fig. 3(B) includes a holding table 10. This holding table 10 has a structure similar to that of the holding table 4 shown in Fig. 3(A). That is, the holding table 10 includes a disk-shaped frame 10a and a disk-shaped porous plate fixed to a recess formed on the upper surface of the frame 4a.

[0045] The holding table 10 is also connected to an X2-axis direction movement mechanism (not shown) and a Y2-axis direction movement mechanism (not shown). Each of the X2-axis direction movement mechanism and the Y2-axis direction movement mechanism includes, for example, a ball screw and a motor. When the X2-axis direction movement mechanism and / or the Y2-axis direction movement mechanism is operated, the holding table 4 moves along the X2-axis direction and / or the Y2-axis direction.

[0046] The holding table 10 is also connected to a rotational drive source (not shown) such as a motor. When the rotational drive source is operated, the holding table 10 rotates around a rotation axis that passes through the center of the upper surface of the holding table 10 and is aligned with the Z2-axis direction.

[0047] The porous plate of the holding table 10 is connected to a suction source (not shown) such as an ejector through a through-hole formed in the bottom wall of the frame 10a. When the suction source is operated, a suction force acts on the space near the upper surface of the porous plate.

[0048] Furthermore, a plurality of clamps (not shown) are provided around the holding table 10 at approximately equal intervals along the circumferential direction of the holding table 10. Each of the clamps can grip the annular frame 19 included in the frame unit 11 and fasten the annular frame 19 at a position lower than the upper surface of the holding table 10.

[0049] Then, when the frame unit 11 is carried into the cutting device 2, the wafer 13 is placed on the holding table 10 via the tape 17 so that the recess 13e formed on the back surface 13d of the wafer 13 fits into the upper part of the holding table 10.

[0050] At this time, the annular frame 19 of the frame unit 11 is gripped by multiple clamps and held at a position lower than the upper surface of the holding table 10. Furthermore, when the suction source communicating with the porous plate of the holding table 4 is operated in this state, the wafer 13 is held on the holding table 10 via the tape 17.

[0051] A head 12 of the laser beam irradiation unit is provided above the holding table 10. This head 12 houses an optical system such as a condenser lens and a mirror. The head 12 is also connected to a Z2-axis direction movement mechanism (not shown). This Z2-axis direction movement mechanism includes, for example, a ball screw and a motor. When the Z2-axis direction movement mechanism is operated, the head 12 moves along the Z2-axis direction.

[0052] The laser beam irradiation unit also has a laser oscillator (not shown) that generates a laser beam with a wavelength (e.g., 365 nm) that is absorbed by the wafer 13. This laser oscillator has, for example, Nd:YAG or the like as a laser medium. When the laser beam LB is generated by the laser oscillator, the laser beam LB is irradiated from the head 12 to the holding table 10 side via an optical system housed in the head 12.

[0053] When performing the singulation step (S1) in the laser processing device 8, first, a rotary drive source connected to the holding table 10 rotates the holding table 10 so that the linear portions (planned division lines) included in the boundaries of the multiple devices 15 formed on the wafer 13 are parallel to the X2 axis direction.

[0054] Next, the Y2-axis direction moving mechanism adjusts the position of the head 12 so that the planned dividing line parallel to the X2-axis direction is positioned in the X2-axis direction in a plan view when viewed from the center of the head 12. Next, the Z2-axis direction moving mechanism raises and lowers the head 12 so that the focal point of the laser beam LB emitted from the head 12 is positioned at approximately the same height as the surface 13a of the wafer 13.

[0055] Next, while irradiating the laser beam LB from the head 12 toward the wafer 13, the X2 axis direction moving mechanism moves the holding table 10 in the opposite direction of the X2 axis direction so that the laser beam LB passes from one end of the wafer 13 to the other in the X2 axis direction. This causes laser ablation along the intended dividing line, dividing the wafer 13.

[0056] In other words, grooves 11a that penetrate the wafer 13 and expose the tape 17 at the bottom are formed in the frame unit 11. Furthermore, the above-described process is repeated until the wafer 13 is divided at all of the boundaries of the multiple devices 15. This completes the singulation step (S1).

[0057] When the singulation step (S1) is performed as described above, the ring-shaped reinforcing portion 14 of the wafer 13 is separated from the chips of the multiple devices 15. Then, in the method shown in Fig. 2, after the singulation step (S1), the ring-shaped reinforcing portion 14 is removed using a rotating cutting blade (removal step: S2).

[0058] 4(A), 4(B), and 4(C) are partial cross-sectional side views each showing a schematic example of the removing step (S2). Briefly, each of FIGS. 4(A), 4(B), and 4(C) shows the removal of the ring-shaped reinforcing portion 14 by bringing the outer peripheral surface of a rotating cutting blade (removing cutting blade) into contact with the upper surface of the ring-shaped reinforcing portion 14.

[0059] This removal step (S2) is performed, for example, by the cutting device 2 shown in Fig. 3(A). Note that in the cutting device 2, prior to performing the removal step (S2), a cutting blade (removal cutting blade) 6c is attached to the tip of the spindle 6a in place of the cutting blade (singulation cutting blade) 6b.

[0060] The cutting blade 6c has a larger blade thickness (width along the Y1 axis direction) than the cutting blade 6b. For example, the blade thickness of the cutting blade 6c is slightly larger than the width of the ring-shaped reinforcing portion 14 along the radial direction of the wafer 13.

[0061] When performing the removal step (S2) in the cutting device 2, first, the X1-axis direction moving mechanism adjusts the position of the holding table 4 and / or the Y1-axis direction moving mechanism adjusts the position of the cutting unit 6 so that the cutting blade 6c is positioned above one end of the ring-shaped reinforcement portion 14 in the Y1-axis direction (see Figure 4(A)).

[0062] Next, the rotation drive source connected to the base end of the spindle 6a rotates the spindle 6a to rotate the cutting blade 6c. Next, while the cutting blade 6c is still rotating, the Z1-axis movement mechanism lowers the cutting unit 6 until the outer circumferential surface of the cutting blade 6c comes into contact with the tape 17 (see FIG. 4(B)).

[0063] As a result, the cutting blade 6c cuts into the ring-shaped reinforcing portion 14, removing one end in the Y1-axis direction of the ring-shaped reinforcing portion 14. Next, while the cutting blade 6c is still rotating, the rotary drive source connected to the holding table 4 rotates the holding table 4 so as to rotate the frame unit 11 at least once (see FIG. 4(C)).

[0064] This removes the entire ring-shaped reinforcing portion 14. Note that specific examples of the removing step (S2) are not limited to those described above. For example, in the removing step (S2), the cutting blade 6c may be caused to cut into the ring-shaped reinforcing portion 14 while the holding table 4 is being rotated.

[0065] In the removing step (S2), the ring-shaped reinforcing portion 14 may be removed by grinding using a rotating cutting blade 6c. Figures 5(A) and 5(B) are partial cross-sectional side views each showing a schematic example of such a removing step (S2).

[0066] When performing the removal step (S2) in this manner, first, the X1-axis direction moving mechanism adjusts the position of the holding table 4 and / or the Y1-axis direction moving mechanism adjusts the position of the cutting unit 6 so that the cutting blade 6c is positioned in the Y1-axis direction when viewed in a plane from one end of the ring-shaped reinforcement portion 14 in the Y1-axis direction.

[0067] Next, the Z1-axis direction movement mechanism raises and lowers the cutting unit 6 so that the lower end of the cutting blade 6c is positioned at a height roughly equal to the lower surface of the ring-shaped reinforcing portion 14 (see FIG. 5(A)). Next, the rotation drive source connected to the base end of the spindle 6a rotates the spindle 6a, and the rotation drive source connected to the holding table 4 rotates the holding table 4 so as to rotate both the cutting blade 6c and the frame unit 11.

[0068] Next, while both the cutting blade 6c and the frame unit 11 are being rotated, the Y1-axis direction moving mechanism moves the cutting unit 6 closer to the holding table 4 until the side of the cutting blade 6c comes into contact with the tape 17 (see FIG. 5(B)). As a result, the entire ring-shaped reinforcing portion 14 is ground and removed by the cutting blade 6c.

[0069] 2, a singulation step (S1) is performed to manufacture chips by singulating a plurality of devices 15 prior to a removal step (S2) of removing the ring-shaped reinforcing portion 14. That is, in this method, the removal step (S2) is performed in a state in which the ring-shaped reinforcing portion 14 and the chips of the plurality of devices 15 are separated from each other. Therefore, in this method, it is possible to prevent the devices 15 from being damaged due to the force applied to the ring-shaped reinforcing portion 14 in the removal step (S2).

[0070] Furthermore, this method makes it possible to remove the ring-shaped reinforcing portion 14 and manufacture chips of a plurality of devices 15 without performing a step of separating the device region 13b of the wafer 13 from the ring-shaped reinforcing portion 14. Therefore, this method makes it possible to improve chip productivity compared to chip manufacturing methods that include this step.

[0071] In addition, the structures and methods according to the above-described embodiments can be modified as appropriate without departing from the scope of the present invention. [Explanation of symbols]

[0072] 2:Cutting device 4: Holding table (4a: frame) 6: Cutting unit 6 (6a: spindle, 6b, 6c: cutting blade) 8: Laser processing equipment 10: Holding table (10a: Frame) 11: Frame unit (11a: Groove) 12: Head 13: Wafer (13a: surface, 13b: device region, 13c: peripheral excess region) (13d: rear surface, 13e: recess) 14: Ring-shaped reinforcement part 15: Device 17: Tape 19: Annular frame

Claims

1. A method for manufacturing chips from a wafer in which a device region in which a plurality of devices are formed is thinned and a central region of a tape in which the peripheral region is attached to an annular frame is attached to a back surface of the wafer in which a recess is formed so as to leave a peripheral excess region surrounding the device region as a ring-shaped reinforcing portion, a singulation step of singulating the plurality of devices by processing the wafer along boundaries of the plurality of devices to produce chips; a removing step of removing the ring-shaped reinforcing portion using a rotating cutting blade after the singulation step, A method for manufacturing a chip that does not include a step of separating the device region and the ring-shaped reinforcing portion by dividing the wafer along the periphery of the device region.

2. 2. The method for manufacturing chips according to claim 1, wherein in the singulation step, the plurality of devices are singulated using a rotating singulation cutting blade or a laser beam having a wavelength absorbed by the wafer.

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