JP3421523B2 - Wafer splitting method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for dividing a wafer suitable for a gallium nitride semiconductor light emitting diode. 2. Description of the Related Art Conventionally, semiconductor elements have been formed by laminating semiconductor layers in a wafer state, and thereafter dividing the wafer into so-called chips (individual elements) by a scribe method or a dicing method. However, in a single-wavelength light emitting diode or the like, a semiconductor layer of the same crystal system is not directly stacked on a substrate of the same crystal system, but semiconductor layers are stacked on substrates of different crystal systems. For example, when a violet, blue or green light-emitting diode is obtained with a gallium nitride-based crystal, a gallium nitride-based semiconductor layer is laminated on a sapphire substrate. In such a case, the sapphire substrate is hexagonal and is cleaved. Have no sex. [0003] When a semiconductor layer is grown on a substrate having such a different crystal system, and when the wafer is divided, as disclosed in Japanese Patent Application Laid-Open No. Hei 5-315646, for example. In addition, even if it is cut by the dicing method or split by the scribe method, cracks and chipping of the cut surface are liable to occur as it is, and the shape of the chip tends to be distorted. Especially when the semiconductor layer is a light emitting diode,
Luminous efficiency may be reduced due to leakage current, etc.
This is disadvantageous, for example, in that the light emission distribution becomes irregular due to deformation of the light emitting layer. [0004] In view of the above, the present invention pays particular attention to the fact that in the initial operation of element division, two orthogonal lines draw the element division at the intersection. It was made. According to the present invention, there is provided a method of dividing a wafer in which a crystalline gallium nitride based semiconductor different from the substrate is laminated on the substrate, wherein the scribing is performed in a first direction from the lamination side of the gallium nitride based semiconductor. Or after forming the groove,
After forming a groove wider and deeper than the scribe line or groove that surely crosses the first scribe line or groove in a second direction orthogonal to the first direction, the wafer is divided. is there. FIG. 1 is a perspective view of a wafer on which a gallium nitride based semiconductor used in a first embodiment of the present invention is laminated, and 1 is a sapphire substrate 1 having a thickness of 100 to 500 μm. is there. On the surface of the sapphire substrate 1, n-type Ga _a
Al _1-a N (0 ≦ a ≦ 1) buffer layer 2, n-type Ga _b A
l _1-b N (0 ≦ b ≦ 1) cladding layer 3, i-type Ga _x Al
_{1-x N (0 ≦ x} ≦ 1) light emitting layer 4, p-type Ga _c Al _1-c N
(0 ≦ c ≦ 1) A clad layer 5 and a cap layer 6 are sequentially laminated, and electrodes 7 and 8 are further provided. Such a semiconductor layer is at most dozens of micrometers. In such a wafer, scribing is performed in the first direction from the side of the stacked semiconductor layers. Scribing is to insert a marking line with a diamond needle or the like. Next, scribing is performed in a second direction orthogonal to the first direction. Although the first and second scribe lines 11 and 12 provided in this manner are shallow, in this state, the scribe line 12 which has been scribed later is generally a needle jump by the scribe line 11 provided earlier. Or the scribe line 11 provided earlier is pulled by the scribe performed later, and the semiconductor film or the like is turned up at the intersection. Therefore, a hole 13 is formed through the sapphire substrate 1 at the intersection of the scribe lines 11 and 12 with a laser beam or the like. Then the sapphire substrate 1 side (back side)
Then, the wafer is divided by pressing with a roller or the like. By doing so, for example, when no hole was provided at the intersection, chipping of about 35% occurred, but it was reduced to about 15%. [0009] Such division is substantially the same as the corner of the chip in the wafer, such that cracks and chipping occur in the form of, for example, projecting to the right shoulder of the chip, so that the other shapes are less likely to crack. Since it is generated with a tendency, it is considered that there is a so-called easy-to-break (easily chipped) directionality depending on how to scribe or the like. The above-described dividing method is suitable for a case where the sapphire substrate is relatively thin, such as 100 to 300 μm. When the sapphire substrate is thick, it is preferable to provide a groove instead of the scribe lines 11 and 12 in accordance with the dicing method, and the scribe line and the dicing groove may be selectively used from the front surface and the back surface of the wafer. By such a method, the yield was increased by making it easier to divide the intersection again, but the grooves and holes provided at the intersection were more preferably deeper than the scribe lines and dicing grooves provided for separation. . Further, at the intersection, holes or grooves may be provided with a tool like a drill without using a laser beam machine. In the case of providing a groove, it is most preferable to form a cross-shaped groove from the sapphire substrate side even if the groove itself is shallow. FIG. 2 is a perspective view of a wafer showing another embodiment of the present invention. Each layer of the wafer is the same as that of FIG. 1, and a crystalline gallium nitride based semiconductor different from the substrate is laminated on the substrate. FIG. In this example, the grooves 14 are formed by etching or dicing in the first direction.
Is formed, the first groove 14 is securely traversed in a second direction orthogonal to the groove 14 in the first direction by another wide and sharp dicing blade as shown in FIG. After forming the groove 15 wider and deeper than the first groove 14 to be formed, the wafer is divided. In this method, as in the previous example, the occurrence of a peculiar easily crackable direction in the substrate 1 or the like at the intersection of the grooves 14 and 15 is prevented, and the crack is made in the desired direction at the intersection. Also in this case, when the sapphire substrate 1 is thin, scribe lines may be used instead of the grooves 14 and 15, but care must be taken so that the semiconductor thin film is not peeled off by the scribe lines when the later grooves are provided. As described above, it is possible to prevent the occurrence of a peculiar easily crackable direction at the intersection due to marking or groove cutting, so that undesired chipping does not occur.
Even if chipping or the like occurs in the groove, the light emission characteristics were not adversely affected.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a main part of a wafer for explaining an embodiment of the present invention. FIG. 2 is a perspective view of a main part of a wafer for explaining a second embodiment of the present invention. [Description of Signs] 1 sapphire substrate 11 scribe line 12 scribe line 13 hole 14 groove 15 groove

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-166933 (JP, A) JP-A-7-131069 (JP, A) JP-A-5-343742 (JP, A) JP-A-5-343742 283758 (JP, A) JP-A-4-312955 (JP, A) JP-A-7-273069 (JP, A) JP-A-51-118187 (JP, A) JP-A-53-237909 (JP, A) JP-A-56-169347 (JP, A) JP-A-9-298339 (JP, A) JP-A-61-131583 (JP, A) JP-A-8-153393 (JP, A) (58) (Int.Cl. ⁷ , DB name) H01L 33/00 H01L 21/301 H01L 21/86 H01S 5/00-5/50

Claims (1)

(1) In a method for dividing a wafer in which a crystalline gallium nitride-based semiconductor different from that of a substrate is laminated on a substrate, the first gallium nitride-based semiconductor is firstly stacked from the lamination side .
Scribe or groove formation in the direction of
After forming a groove that is wider and deeper than the scribe line or groove that surely crosses the first scribe line or groove in a second direction orthogonal to the direction of, the wafer is divided. A method for dividing a wafer, comprising: