JP2849602B2 - Joining method of single crystal sapphire - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for bonding single crystal sapphire.

[Conventional technology and its problems]

Regarding the joining of single crystal sapphire, see JP-A-59-233000.
According to this method, two single-crystal sapphires are arranged such that their crystal plane orientations coincide at an angle within 1 °, and their ends are fused and joined. .

However, according to the above-mentioned joining method, there is a problem that the shape of the joining portion is destroyed due to melting and joining, so that a joined body having a precise shape cannot be formed.

In addition, when the joining area is increased when the joining surface is melted, it is difficult to uniformly melt the entire joining surface, and thus there is a problem that the joining is not suitable for joining over a large area.

[Object of the invention]

Accordingly, the present invention has been completed in view of the above circumstances, and an object of the present invention is to provide a method for joining single crystal sapphire which is suitable for joining over a large area without deforming the shape near the joining surface. is there.

[Means for Solving the Problems] The method for bonding single crystal sapphire according to the present invention is characterized by comprising the following steps A and B in order.

A: The bonding surfaces of a single crystal sapphire body having a bonding surface having a center line average roughness of not more than Ra500 ° are in close contact with each other.

B: A single crystal sapphire body in a close state is placed in a vacuum furnace and heated in a vacuum.

[Action]

In the case of the above joining method, the joining can be made firmly without melting, and the joining surface can be made large, whereby a large joined body having a precise shape can be made.

〔Example〕

 Hereinafter, the present invention will be described with reference to examples.

In this example, as shown in FIG. 1, two disk-shaped single-crystal sapphire plates 1 and 2 (50 mm in diameter and 0.5 mm in thickness) were prepared.
The joining principal surfaces 1a and 2a of the two plates are completely overlapped, and a joined body is obtained by the steps A and B described later. In addition, 1b, 2b
Is the non-bonded main surface of each.

Crystal Orientation Single crystal sapphire is hexagonal, and according to the orientation shown in FIG. 2, it is (0001) perpendicular to the C axis of the crystal.
There is a surface (commonly referred to as C-plane), a _1-axis rotational symmetry direction so that and 120 ° central angle in a direction perpendicular to the C axis, a ₂ axis, there is a _3-axis, these The three planes perpendicular to the three axes are crystallographically equivalent, and the plane is the (110) plane (generally called the A plane). Also, a plane perpendicular to the R axis inclined at 57.6 ° in the m axis direction (the m axis direction is an axis perpendicular to the side surface of the hexagonal prism) with respect to the C axis is (102).
Plane (generally called an R plane).

As described above, there are three types of plane orientations. In order to obtain the desired plane orientations of the bonding principal surfaces 1a and 2a, it is also possible to obtain an existing single-crystal sapphire by chamfering using a diamond tool. In the following EFG method (Edge-def
ined Film-fed Growth method).

EFG method In producing a sapphire plate, a single crystal is grown so that the plate surface has a predetermined plane orientation.

That is, a high-purity alumina is melted in an inert atmosphere, and a ribbon-shaped sapphire single crystal growing molybdenum die having a slit therein is positioned so as to be in contact with the melt. The sapphire seed having a predetermined plane orientation is brought into contact with the alumina melt at the upper end of the die, and then the seed is pulled upward to grow single crystal sapphire. One main surface of the sapphire plate pulled up by this has a predetermined plane orientation.

 Next, both steps A and B will be described.

Step A Sapphire plate 1 having such a predetermined plane orientation
In manufacturing and bonding, the main bonding surfaces 1a and 2a are polished as a step A, and the center line average roughness R of the main surface is obtained.
It is necessary to set a to 500 mm or less, preferably 300 mm or less.

Conventionally known means for polishing a single crystal may be employed for such polishing. In this example, lapping was first performed using diamond powder dissolved in lapping oil, and then polishing was performed using a cloth. Thus, the center line average roughness Ra as described above was obtained.

Generally, after the above-mentioned polishing, the joining main surfaces 1a and 2a are contaminated by organic substances and dust. Therefore, cleaning is performed with a detergent, isopropyl alcohol, or the like.

After that, both sapphire plates 1 and 2 are immediately superimposed. In this superposition, the two joining main surfaces 1a and 2a are merely in close contact over the entire surface, and are easily separated by applying an appropriate force. Therefore, in performing the next step B, the intimate contact body is placed at a predetermined position inside the vacuum annealing furnace and slightly pressed from the non-bonding main surfaces 1b and 2b (for example, about 10 to 50 g per unit area of the sapphire plate). / cm ² ). Thereby, the close contact state is maintained.

Step B According to the step B, for example, a vacuum annealing furnace equipped with an induction heating method is used to degas and significantly increase the degree of vacuum. For example, in experiments conducted by the present inventors, the degree of vacuum was set to 1 × 10 ⁻⁵ Torr.
Hereinafter, it is considered that the pressure is preferably set to 1 × 10 ⁻⁶ Torr or less. However, the pressure is not necessarily limited to the above numerical range, and the degree of vacuum may be further increased.

The annealing temperature is appropriately determined within a range in which sapphire itself does not melt. According to experiments repeatedly performed by the present inventors, the annealing temperature may be 1000 ° C. or higher, preferably 1500 ° C. or higher.

When the step B is completed, the temperature may be gradually lowered to room temperature.

Shift angle of plane orientation between joining main surfaces 1a and 2a For example, when both joining main surfaces 1a and 2a are C-planes, there may be a shift angle of plane orientation between the two.

That is, according to the joining state shown in FIG. 3, the deviation angle θ between the respective C axes of the sapphire plates 1 and 2 corresponds to the deviation angle of the plane orientation.

 Next, examples performed by the present inventors will be described.

(Example 1) Polishing was performed so that the joining principal surfaces 1a and 2a were both R surfaces and the center line average roughness was 20 °, and after washing, the two sapphire plates 1 and 2 were immediately superimposed while being pressed. . In this case, the superposition was performed with the misalignment angle of the plane orientation between the two joining principal surfaces 1a and 2a set within 1 °.

Next, the degree of vacuum is set to 3 to 4 × 10 ⁻⁷ Torr and the annealing temperature is set to 16
The temperature was set to 80 ° C., and vacuum annealing was performed for 4 hours to obtain a joined body.

The joined body thus obtained was cut into a square having a side of 10 mm, and the joining strength was measured as shown in FIG. 4 or FIG.

In FIG. 4, reference numeral 3 denotes the above-mentioned square body, on both main surfaces thereof metallized with nickel metal, and further, a metal round bar 4 of 3 mmφ is brazed to both main surfaces. Is pulled in the direction indicated by the arrow X.

When such a tensile strength test was performed, it was peeled off from the metallized portion first.

According to the measuring method shown in FIG. 5, both main surfaces of the square body 3 are metallized with nickel metal, and two rectangular SUS plate-like bodies 5 each having a short side of 10 mm are prepared. Then, brazing is applied over the entire surfaces of the two main surfaces, and both plate-like members 5 are pulled in the arrow Y direction.

Even when such a tensile strength test was performed, it was peeled off from the metallized portion first.

(Example 2) In this example, in (Example 1), the respective plane orientations of the joining main surfaces 1a and 2a are set as shown in Table 1, and the center line average roughness is also set. Were set to the same conditions as in (Example 1), whereby six types of joined bodies were produced. For the joints A, B, and F, the main joining surface 1 of both
The superposition was performed by setting the deviation angle of the plane orientation between a and 2a within 1 °.

When each of the thus obtained joined bodies was subjected to two types of tensile joining strength tests in the same manner as in (Example 1), all of the joined bodies were peeled off from the metallized portion first.

The present inventors have proposed a sapphire plate in which the bonding principal surface has an R-plane orientation, and the lapping and polishing processes are not performed on the principal surface, and the center line average roughness is increased to 2000 °. Individual pieces were prepared, the angle of the plane orientation between the two joining principal surfaces was set to within 1 °, and the other conditions were set to the same conditions as in this example. An attempt was made to produce a joined body, but no joining was performed. .

(Example 3) Next, with respect to the joined body of the present invention and the joined bodies A and B of (Example 1), the present inventors set the misalignment angle of the plane orientation between the joining principal surfaces 1a and 2a to 5 ° and 15 °, respectively. , 40 ゜, 70 ゜ or 90 ゜ were set and superimposed.

The 15 types of joined bodies thus obtained were subjected to two types of tensile joint strength tests in the same manner as in (Example 1).
All peeled off from the metallized part first.

〔The invention's effect〕

As described above, according to the joining method of the present invention, the single crystal sapphire can be firmly joined without melting part of the single crystal sapphire, thereby providing a joined body having a complicated and precise shape.

Further, according to the present invention, it is possible to provide a high-reliability bonded body in which a desired shape can be obtained because the bonding surface can be enlarged.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a bonding method of an embodiment, FIG. 2 is an explanatory view showing a crystal plane orientation of single crystal sapphire, FIG. 3 is a partial cross-sectional view of a bonded body, and FIGS. It is sectional drawing showing the method of a joining strength test. 1,2 …… Sapphire plate 1a, 2a …… Main surface of joining

Claims (1)

(57) [Claims] 1. A method for bonding single crystal sapphire, comprising the following steps A and B: A: The bonding surfaces of a single crystal sapphire body having a bonding surface having a center line average roughness of not more than Ra500 ° are in close contact with each other. B: A single crystal sapphire body in a close state is placed in a vacuum furnace and heated in a vacuum.