JPS59151514A - Manufacture of lithium niobate single crystal element - Google Patents

Abstract

PURPOSE:To prevent cracks and chipping and to improve the yield by applying dicing processing to a lithium niobate single crystal in the direction of a line of intersection between a line of cleavage of the crystal for an elastic surface wave filter and a wafer surface. CONSTITUTION:The 64 deg. Y-cut is applied to the wafer so that a straight line segment A rotating the Y axis to the Z axis by 64 deg. is a normal of the face of wafer on the Y-Z plane of a hexagonal unit cell of the lithium niobate single crystal. The planes of the single crystal are (-1012), (01-12) and (1-102) in this case. Then, an oriented flat plane 3 is cut so that a line of intersection between the oriented flat plane 3 and the wafer plane is in parallel with a line of intersection between the (1-102) plane and the wafer plane. The direction N is in parallel with the line of intersection between the (01-12) plane and the wafer plane. Further, the M direction is in parallel with the line of intersection between the (1-102) plane and the wafer plane. Further, the dicing processing is applied to the crystal in a direction in parallel with the directions M and N to form slots 4, 5. The single crystal element 6 is formed by slicing the crystal along the slots.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for manufacturing a lithium niobate single crystal element for a surface acoustic wave filter.

[Technical background of the invention and its problems]

Conventionally, the main components for surface acoustic wave filters are:
It was manufactured by cutting a wafer from a lithium niobate (LiNb0.) single crystal ingot, dicing it to make grooves, and then cutting it. However, in conventional dicing processing, the dicing line does not necessarily coincide with the direction of intersection between the interosseous surface of the lithium niobate (LiNbO5) single crystal and the wafer surface. Therefore, during the dicing process using a grinding wheel, cracks and chips that separate multiple elements are likely to occur between the bones, resulting in a decrease in product yield, and the large cutting depth causes wear of the grinding wheel for dicing. This caused the problem of reduced grinding efficiency.

[Purpose of the invention]

An object of the present invention is to provide a method for manufacturing a lithium niobate single crystal element that can prevent cracking and chipping as much as possible.

[Summary of the invention]

Dicing is performed in the direction of the intersection between the interosseous surface of the lithium niobate single crystal and the wafer surface.

[Embodiments of the invention]

Hereinafter, the present invention will be explained based on examples with reference to the drawings.

First, after manufacturing a lithium niobate single crystal using a single crystal manufacturing apparatus (not shown), in the Y-Z plane of the hexagonal unit cell of lithium niobate shown in FIG. so that the straight line A rotated by a degree becomes the normal to the wafer surface.
The wafer (2) is rotated 64 degrees and Y-cut using a slicing device (not shown). ~ At this time, the crystal opening planes of the lithium niobate single crystal are 0, (1012), (0112), (
1102), but for example, the Labor Kai (110)
2), The direction of intersection of (0112) and the wafer surface, which is the main surface of the wafer (2), is the M direction and the direction M, which has a constant angular relationship with the surface (3) of the ori 7, as shown in FIG. It is set to be in the N direction. That is, the M direction is the interosseous surface (
The direction parallel to the line of intersection between the interosseous surface (0112) and the wafer surface, and the N direction is the direction parallel to the line of intersection between the interosseous surface (0112) and the wafer surface. Therefore, after producing an ingot of lithium niobate single crystal, the interosseous surface (1102)
Grind the ori 72 surface (3) so that the line of intersection of the tJm (txo2) with the wafer surface and the line of intersection of the orientation flat surface (3) and the wafer surface are parallel to each other. Therefore, the above M direction is aligned with the ori 72 plane (
3) and the wafer surface. Then, the wafer (2) is held at a fixed position with respect to the surface (3) of the ori 72 and placed in a dicing device (not shown) so that the dicing line is parallel to the M direction and the N direction. Dicing is performed at predetermined intervals so that one first dicing line (4)...(parallel to the N direction) is a cutting groove as shown in FIG. 4) Form a second dicing line (5) (parallel to the M direction) that intersects with.... Thereafter, the lithium niobate single-crystal element (6) as shown in FIG. 3 is obtained by cutting into pieces. The angle θ1 of this element (6). θ2 is 50 degrees and 130 degrees, respectively.

When a lithium niobate single crystal element is manufactured as described above, each side (7), (8), (9) of the element (6)
After dicing, it is formed so that the direction in which the ridge and inter-bone surface intersect with the well and surface are parallel to each other.
It is extremely unlikely that cracks or chips generated in the cutting groove during cutting will propagate along the interosseous surface and separate individual elements, and the yield in the cutting process will be significantly improved.

In addition, even if the groove depth is made shallower than before during dicing, it can be easily divided. The effect of increasing the life of a circular thin-blade diamond grindstone having a thickness of less than the rim was obtained.

In addition, as another example, a combination of other interosseous surfaces, that is, a combination of an interosseous surface (0112) and an interosseous surface (Tox2) (see FIG. 4; angle θg = 1301Jf,), θ
4=5 billion)), interosseous surface (oxT2), 41 surface (xo
1□), combination with 41 plane (noz) (see Figure 5;
An arbitrary combination may be selected from the angle θ angle=θa=so(i)), and dicing may be performed in the direction of the intersection of the interosseous surface and the wafer surface. At this time, the orientation flat surface is created by identifying the orientation of any one of the combinations of interosseous surfaces using X-ray diffraction (X-ray diffraction) and grinding.

〔Effect of the invention〕

According to the present invention, there is no possibility that generated cracks or chips will propagate along the interosseous surface and separate the individual elements, thereby improving the yield. In addition, since the cutting direction of the element during dicing matches the direction in which the interosseous surface intersects with the wafer surface, subsequent cleavage is easy even if the groove depth is shallower than before, and the grinding wheel has a long lifespan. increases.

[Brief explanation of drawings]

Figure 1 shows the hexagonal unit cell of lithium niobate, Figure 2
The figures show a wafer in which grooves in a predetermined direction have been formed by dicing in one embodiment of the present invention, FIG. 3 shows a device obtained in one embodiment of the present invention, and FIG. figure,
FIG. 5 is a diagram showing a device obtained according to another embodiment of the present invention. (2)...Wafer, (6)...Element. Agent: Patent Attorney Noriyuki Chika (1 person)

Claims (1)

[Claims] Rotated 64 degrees from a lithium niobate single crystal ingot
The process of cutting out the cut wafer and the interosseous surface of the above-mentioned wafer (
1012), (0112), (1102) and the above-mentioned wafer), and a step of cutting the grooved wafer into a plurality of elements. A method for manufacturing a lithium niobate single crystal element, comprising: