JP2013197303A - Semiconductor device manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce chipping generated by dicing of a substrate.SOLUTION: A semiconductor device manufacturing method comprises: a first process of irradiating with laser beams a rear face of a substrate 6 which has a plurality of integrated circuits separated by scribe lines, in regions opposite to the scribe lines to achieve amorphization 22 of the rear face side of the substrate without scattering a material of the rear face of the substrate 6; and a second process of dicing by rotating dicing means after the first process, the substrate 6 along the scribe lines with a surface of the substrate 6 being directed toward a rotation center side of the dicing means.

Description

  The present invention relates to a method for manufacturing a semiconductor device.

  A wafer level CSP (Chip Size Package) is a package of a semiconductor device miniaturized to the limit. A semiconductor device packaged in a wafer level CSP is manufactured, for example, by forming external terminals on an integrated circuit on a wafer and dividing the wafer into chips.

JP 2011-40611 A

  The wafer is divided into chips by a dicing blade that rotates at high speed. Large chipping (chips or cracks) occurs on the back surface of the chip divided by the dicing blade.

  For this reason, a semiconductor device in which a package (wafer level CSP or the like) is completed by dicing has a problem that appearance quality is not good. Further, the semiconductor device has a problem that when the chipping is increased, the semiconductor device is easily broken by an external force.

  Patent Document 1 discloses a technique for preventing chipping that occurs when chips are separated into individual pieces. In this technique, a groove is formed on the back surface of the wafer by laser irradiation, and the groove is covered with a resin, and then a dicing process is performed. However, at the time of laser irradiation, the molten silicon is scattered by the energy of the laser beam and adheres to the processing surface and its surroundings. The adhered silicon adheres in the form of particles by rapid cooling and solidification, and the processing surface Becomes an uneven shape. This uneven shape makes it easy for the back surface of the wafer to be peeled off from the dicing tape, resulting in a hindrance to the dicing process.

  Therefore, in order to solve the above problem, according to one aspect of the manufacturing method, an energy beam is applied to a region facing the scribe line on the back surface of the substrate having a plurality of integrated circuits separated by the scribe line on the surface. A first step of amorphizing the back side of the substrate without irradiating and scattering, and after the first step, the surface is directed to the rotation center side of the dicing means by the rotating dicing means. And a second step of dicing the substrate along the scribe line.

  According to this manufacturing method, chipping of the substrate caused by dicing is reduced.

It is process drawing explaining the manufacturing method of the semiconductor device of embodiment. It is process drawing explaining the manufacturing method of the semiconductor device of embodiment. It is process drawing explaining the manufacturing method of the semiconductor device of embodiment. It is sectional drawing of the board | substrate along the IV-IV line of FIG. It is a figure explaining a laser irradiation process. It is a figure explaining a laser irradiation process. It is sectional drawing explaining an example of the shape of an amorphous area | region. It is a figure explaining the mounting | wearing method to the dicing apparatus of a board | substrate. It is a top view explaining the dicing method. FIG. 10 is a cross-sectional view taken along line XX in FIG. 9. It is sectional drawing along the XI-XI line of FIG. It is a top view explaining chipping of a substrate. It is a top view explaining chipping of a substrate. It is sectional drawing along the XIV-XIV line | wire of FIG. It is a top view explaining the dicing of the board | substrate with which the area | region which opposes a scribe line is not amorphized. It is sectional drawing along the XVI-XVI line of FIG. It is a perspective view which shows the back surface of the chip | tip of embodiment. It is a figure which shows the back surface of the chip | tip divided | segmented from the board | substrate which is not amorphized in the area | region which opposes a scribe line. It is a figure explaining the modification of embodiment. It is a figure explaining the modification of embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the technical scope of the present invention is not limited to these embodiments, but extends to the matters described in the claims and equivalents thereof. Note that, even if the drawings are different, corresponding parts are denoted by the same reference numerals, and description thereof is omitted.

  1 to 3 are process diagrams (perspective views) for explaining a method of manufacturing a semiconductor device according to the embodiment.

(1) Back grinding process (FIGS. 1A to 1C)
First, as shown in FIG. 1A, a substrate (wafer) 6 having a plurality of integrated circuits 4 separated by scribe lines 2 on the surface is prepared.

  The integrated circuit 4 is, for example, a logic circuit or a CPU (Central Processing Unit). The substrate 6 is, for example, a wafer in which the integrated circuit 4 is formed on a silicon single crystal substrate having a thickness of about 775 μm.

  FIG. 4 is a cross-sectional view of the substrate 6 taken along line IV-IV in FIG. FIG. 4 shows the central portion of the IV-IV line. A substrate 6 shown in FIG. 4 is a wafer for wafer level CSP.

  As shown in FIG. 4, the integrated circuit 4 includes elements (transistors, resistors, etc.) 8 formed on the surface of the substrate 6, a wiring layer 10 including a multilayer wiring layer, and external terminals (in the example of FIG. 12). The wiring layer 10 may include a rewiring layer. The integrated circuit 4 may have a resin protective layer (not shown) that covers the wiring layer 10.

  The scribe line 2 is an area cut by a dicing process described later. In the example shown in FIG. 4, nothing is formed on the scribe line 2. However, the scribe line 2 may be formed with a TEG (Test Element Group), a marker indicating the position of the scribe line, or the like.

  Next, as shown in FIG. 1B, a surface protection tape 14 is attached to the surface of the substrate 6. The surface protection tape 14 protruding from the substrate 6 is removed. Thereafter, as shown in FIG. 1C, the back surface of the substrate 6 is back-ground (polished) with a rotating ring-shaped grindstone 16. By this back grinding, the substrate 6 has a predetermined thickness (for example, 25 to 700 μm). The pattern on the back side of the substrate 6 shown in FIG. 1C is a saw mark generated by back grinding.

(2) Laser irradiation process (see FIG. 2 (a))
5 to 7 are diagrams for explaining the laser irradiation process. In FIG. 5, elements and bumps formed on the substrate 6 are omitted (the same applies to the following drawings).

  First, from the back-ground back surface, the substrate 6 is seen through, for example, by infrared rays, and a region 18 (see FIG. 5) facing the scribe line 2 is confirmed. A laser beam 20 is applied to the region 18 on the back surface of the substrate. The irradiation with the laser beam 20 is performed by scanning the laser beam 20 along the scribe line as shown in FIG.

  The region 18 facing the scribe line 2 is heated and melted by irradiation with the laser beam. When the laser beam passes, the melted portion is rapidly cooled, and an amorphous region 22 in which the single crystal is changed to amorphous is formed along the scribe line 2 as shown in FIGS.

  By the way, a single crystal becomes brittle when it becomes amorphous. Therefore, the amorphous region 22 becomes more fragile than the surrounding region.

  As shown in FIG. 6, the substrate 6 is amorphized to the middle of the thickness by the irradiation of the laser beam 20. For example, the substrate 6 is amorphized to approximately half the thickness. However, it is preferable not to be amorphous within 20 μm of the substrate surface. More preferably, it is preferable that the surface of the substrate is not amorphized within 30 μm. If the substrate is melted to the vicinity of the surface due to amorphization, the integrated circuit 4 may be deteriorated.

  The width of the amorphous region 22 is preferably about the same as the width of the scribe line 2 as shown in FIG. The amorphous region 22 may be narrower than the scribe line 2, but is preferably wider than a dicing blade described later.

  In the embodiment, the laser beam is applied to the substrate 6 so that the molten substrate 6 does not boil. When the substrate 6 boils, the molten substrate becomes fine particles and scatters and adheres to the back surface of the substrate 6. The attached fine particles deteriorate the appearance quality of the semiconductor device. Furthermore, the adhered fine particles make the dicing process described later difficult.

  Therefore, it is preferable that the substrate 6 is heated to a temperature not lower than the melting point of the constituent material and lower than the boiling point (when the substrate is Si, it is not lower than 1,420 ° C. and not higher than 2,599 ° C.). Whether or not the substrate has boiled can be confirmed by observing the shape of the amorphous region 22.

  FIG. 7 is a cross-sectional view illustrating an example of the shape of the amorphous region.

  As shown in FIG. 7, the substrate 6 partially evaporates when the heating temperature increases, and a depression is generated in the amorphous region 22a. If the substrate 6 is only melted and does not boil, the depth d of the recess is about 5 μm at most. Therefore, it is possible to determine whether or not the back surface of the substrate 6 has boiled by observing the depth d of the recess.

  In the embodiment, the spot diameter, power, scanning speed, and the like of the laser beam 20 are set so that the region 18a facing the scribe line 2 after irradiation with the laser beam 20 is not recessed 5 μm or more (preferably 3 μm or more) from the surroundings. adjust. Thereafter, the laser beam 20 is irradiated onto the substrate 6.

  The laser beam can be applied to the substrate 6 by, for example, a laser marking device or a laser scribing device. The wavelength of the laser beam is preferably a wavelength absorbed by the substrate (for example, 200 nm to 1,000 nm for a Si substrate).

  The power of the laser beam is, for example, 0.1 W to 10 W. The form of laser oscillation may be either continuous oscillation or pulse oscillation.

(3) Dicing process (FIGS. 2B to 3A)
Next, as shown in FIG. 2B, the substrate 6 is disposed at the center of the frame ring 24, and the dicing tape 26 is attached to the back surface of the substrate 6 and the frame ring 24. As a result, the substrate 6 is fixed to the dicing tape 26.

  Thereafter, the dicing tape 26 protruding from the frame ring 24 is removed, and the surface protection tape 14 covering the surface of the substrate 6 is further removed as shown in FIG.

  Next, the substrate 6 fixed to the dicing tape 26 is mounted on a dicing apparatus (so-called dicing saw) having a dicing blade. FIG. 8 is a diagram for explaining a method of mounting the substrate 6 on the dicing apparatus.

  As shown in FIG. 8, the substrate 6 is mounted on the dicing apparatus so that the surface thereof faces the rotation center 30 side of the dicing blade 28. The height of the dicing blade 28 is adjusted so that the tip of the dicing blade 28 enters the dicing tape 26. When the dicing blade 28 is attached to the rotation shaft, the center of the rotation shaft becomes the rotation center 30 of the dicing blade 28.

  In this state, the dicing blade 28 is rotated, and the substrate 6 is diced (cut) along the scribe line 2 as shown in FIG. The dicing blade 28 is a dicing means in which diamond particles or the like are fixed to a base material such as metal with a bond material.

  FIG. 9 is a plan view for explaining the dicing method. FIG. 10 is a cross-sectional view taken along line XX in FIG. 11 is a cross-sectional view taken along line XI-XI in FIG.

  The dicing blade 28 cuts the substrate 6 along the scribe line 28 as shown in FIG. The dicing blade has a width W1 narrower than the scribe line 2. The width W2 of the scribe line 2 is, for example, 40 to 100 μm. The width W1 of the dicing blade 28 is preferably 10 to 30 μm narrower than the width W2 of the scribe line 2.

  As shown in FIG. 10, the dicing blade 28 cuts the entire thickness of the substrate 6 and a part of the dicing tape 26.

  By the way, as shown in FIG. 3A, the scribe line 2 extends in a second direction 32b intersecting (for example, orthogonal to) the first direction 32a and the first direction. Therefore, the substrate 6 is divided for each integrated circuit 4 by the dicing.

  As shown in FIG. 11, the width W <b> 3 of the amorphous region 22 is wider than the width W <b> 1 of the dicing blade 28. Therefore, the chipping is confined in the amorphous region as will be described later.

―Chipping―
12 to 13 are plan views for explaining chipping of the substrate 6. 14 is a cross-sectional view taken along line XIV-XIV in FIG.

  FIG. 12 shows a dicing blade 28 cutting the substrate 6. The dicing blade 28 cuts the substrate 6 by being pushed in the traveling direction 33 while rotating. At this time, the dicing blade 28 receives a reaction (cutting resistance) 36 from the substrate 6 and accumulates stress.

  When this stress reaches the threshold value, as shown in FIG. 13, the tip of the dicing blade 28 vibrates and the stress is released.

  As shown in FIG. 10, the dicing blade 28 rotates from the front surface to the back surface of the substrate 6. Accordingly, a force for peeling off the substrate body acts on the back surface of the substrate 6. When the tip of the dicing blade 28 vibrates, as shown in FIG. 14, the back surface side of the substrate 6 is destroyed by the vibration impact and the force to be peeled off from the substrate.

  An amorphous region 22 is formed on the back side of the substrate 6. As described above, since the amorphous region 22 is brittle, it is destroyed before the stress of the dicing blade 28 increases. For this reason, the vibration of the dicing blade 28 is weak, and a small chipping 34 is generated on the substrate 6.

  The amorphous region 22 is surrounded by a single crystal that is not easily destroyed. Therefore, as shown in FIG. 14, the destruction of the substrate 6 is confined in the substantially amorphous region 22. For this reason, the chipping 34 of the substrate 6 is further reduced.

  FIG. 15 is a plan view for explaining dicing of the substrate 6a in which the region facing the scribe line 2 is not amorphized. 16 is a cross-sectional view taken along line XVI-XVI in FIG. In the example shown in FIGS. 15 and 16, the entire substrate is a single crystal that is not easily broken. Therefore, the threshold value at which the dicing blade vibrates is high. For this reason, as shown in FIG. 15, the vibration 35 of the dicing blade increases. As a result, the substrate 6a is largely destroyed as shown in FIG. 16, and the chipping 34a becomes large.

  When the dicing blade 28 is rotated from the back surface to the front surface of the substrate 6, chipping occurs on the surface of the substrate 6 and the integrated circuit 4 is destroyed. Therefore, such dicing is hardly performed.

(4) Subsequent process (FIGS. 3B to 3C)
Next, as shown in FIG. 3B, the dicing tape 26 is cured by irradiating the dicing tape 26 with ultraviolet rays 38 from the back side of the substrate 6. Thereby, the divided substrate (chip) is easily peeled off from the dicing tape 26.

  Thereafter, the chip 38 is picked up from the dicing tape 26 as shown in FIG. The chip 38 is a semiconductor device packaged by a wafer level CSP.

  FIG. 17 is a perspective view showing the back surface of the chip (semiconductor device) 38. As shown in FIG. 17, according to the embodiment, the chipping 34 generated in the semiconductor device 38 is fine. For example, the width of the chipping 34 is about 5 μm to 15 μm. Therefore, the appearance quality of the semiconductor device 38 is good.

  FIG. 18 is a perspective view showing the back surface of the chip 38a divided from the substrate 6a in which the region facing the scribe line 2 is not amorphized. As shown in FIG. 18, a large chipping 34a is generated on the substrate 6a.

  The length L of the chipping 34a is, for example, about 200 μm. The width W4 of the chipping 34a is, for example, 50 to 60 μm. The depth of the chipping 34a is, for example, 30 to 100 μm.

  Therefore, the appearance quality of the chip 38a is poor. Such a chip 38a is weak against external force and easily broken.

(5) Modification FIGS. 19 and 20 are diagrams for describing a modification of the embodiment.

  If the scanning speed of the laser beam is increased to suppress the depth of the amorphous region 22, the width of the amorphous region may become too narrow than the scribe line 2.

  In such a case, as shown in FIG. 19, the laser beam 20 is irradiated a plurality of times (for example, twice) so that the irradiation position in the lateral direction 40 of the scribe line 2 (that is, the direction perpendicular to the scribe line) is different. ) You may scan.

  In the example shown in FIG. 19, the first laser beam 20a is a laser beam in the first scan. The second laser beam 20b is a laser beam in the second scan.

  As shown in FIG. 20, the amorphous region 22a formed by the first laser beam 20a and the amorphous region 22b formed by the second laser beam 20b are combined to form an amorphous region 22c having substantially the same width as the scribe line 2. Therefore, the amorphous region can be thickened to the same extent as the scribe line 2 by scanning the laser beam a plurality of times.

  In the above example, the substrate is irradiated with a laser beam to locally amorphize the back surface of the substrate without scattering. However, instead of the laser beam, the substrate may be irradiated with another energy beam (for example, an electron beam).

  In the above example, the substrate is a silicon single crystal substrate. However, the substrate may be a single crystal at least on the back side. For example, the substrate may be a SIO (Silicon on Insulator) substrate or a compound semiconductor substrate.

  In the above example, the substrate is diced using a dicing blade in which diamond is fixed to a metal base material. However, the substrate may be diced by other dicing means (for example, an artificial grindstone in which a binder is mixed with an abrasive and sintered).

  In the above example, the cross section of the laser beam is a spot (dot). However, it is also possible to irradiate the back surface of the substrate with a laser beam having a line-shaped cross section to make the regions facing the scribe line all amorphous.

  In the above example, the substrate is amorphized to the middle of its thickness. However, if the scribe line is sufficiently wide, the substrate surface may be amorphized. In this case, heating the integrated circuit can be avoided by making the amorphous region sufficiently narrower than the scribe line.

  Regarding the above embodiment, the following additional notes are disclosed.

(Appendix 1)
A back surface of the substrate having a plurality of integrated circuits separated by a scribe line is irradiated with an energy beam on a region facing the scribe line on the back surface of the substrate, so that the back surface side of the substrate is not scattered. A first step of amorphization;
After the first step, there is a second step of dicing the substrate whose surface is directed to the rotation center side of the dicing means by the rotating dicing means along the scribe line. Method.

(Appendix 2)
In the method for manufacturing a semiconductor device according to attachment 1,
The substrate is a single crystal at least on the back side,
In the first step, the substrate is amorphized to the middle of its thickness.

(Appendix 3)
In the method for manufacturing a semiconductor device according to appendix 1 or 2,
A method of manufacturing a semiconductor device, wherein a dicing tape is attached to the back surface of the substrate after the first step and before the second step.

(Appendix 4)
In the method for manufacturing a semiconductor device according to any one of appendices 1 to 3,
In the first step, the energy beam adjusted so that the region irradiated with the energy beam is not depressed more than 5 μm from the surroundings is irradiated.

(Appendix 5)
In the method for manufacturing a semiconductor device according to any one of appendices 1 to 4,
In the first step, the energy beam is irradiated a plurality of times so that an irradiation position in a direction perpendicular to the scribe line is different.

(Appendix 6)
In the method for manufacturing a semiconductor device according to any one of appendices 1 to 5,
The method of manufacturing a semiconductor device, wherein the energy beam is a laser beam or an electron beam.

2 ... scribe line 4 ... integrated circuit 6 ... substrate 8 ... element 10 ... wiring layer 22 ... amorphous region 30 ... center of rotation 34 ... chipping

Claims (5)

A back surface of the substrate having a plurality of integrated circuits separated by a scribe line is irradiated with an energy beam on a region facing the scribe line on the back surface of the substrate, so that the back surface side of the substrate is not scattered. A first step of amorphization;
After the first step, there is a second step of dicing the substrate whose surface is directed to the rotation center side of the dicing means by the rotating dicing means along the scribe line. Method. In the manufacturing method of the semiconductor device according to claim 1,
The substrate is a single crystal at least on the back side,
In the first step, the substrate is amorphized to the middle of its thickness. In the manufacturing method of the semiconductor device according to claim 1 or 2,
A method of manufacturing a semiconductor device, wherein a dicing tape is attached to the back surface of the substrate after the first step and before the second step. In the manufacturing method of a semiconductor device according to any one of claims 1 to 3,
In the first step, the energy beam adjusted so that the region irradiated with the energy beam is not recessed more than 5 μm from the surroundings is irradiated. In the manufacturing method of the semiconductor device of any one of Claims 1 thru / or 4,
In the first step, the energy beam is irradiated a plurality of times so that an irradiation position in a direction perpendicular to the scribe line is different.