JPS6226459Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Technical field of the invention The invention relates to the structure of a substrate holder that improves workability in LPE film growth operations.

(b) Background of the Technology Epitaxial technology, in which crystals of the same type or different types having the same crystal axis are grown on a single crystal substrate, is widely used in semiconductors and magnetic bubble memory devices.

There are two types of epitaxial growth: liquid phase epitaxial growth (LPE) performed in a melt and vapor phase epitaxial growth performed in a gas atmosphere, but this invention is used for liquid phase epitaxial growth (hereinafter referred to as LPE). The present invention relates to a substrate holder.

The present invention will be explained below using LPE growth of a magnetic garnet film as an example.

The magnetic garnet used as a material for magnetic bubble memory is formed by LPE growth on a non-magnetic gadolinium gallium garnet Gd ₃ Ga ₅ O ₁₂ (GGG) substrate.

The GGG used as the substrate here has a diameter of 3
Generally, a magnetic film with a thickness of approximately 500 μm in inches is used, and in order to grow a magnetic film with the required composition on this film, an oxide consisting of the necessary garnet component, such as a PbO-B ₂ O ₃ flux, is used. After sufficiently melting using a platinum crucible with
By immersing a GGG crystal substrate (hereinafter referred to as a wafer) in this melt and keeping the liquid temperature below the saturation point,
A magnetic garnet crystal film having the same crystal axis as the GGG wafer is grown on the GGG wafer.

From an economic standpoint, LPE growth requires multiple
This is done by fixing a GGG wafer to a substrate holder and immersing it in the melt, but even though the wafer has a large diameter of 3 inches (76.2 mm), its thickness is approximately
Since it is thin at 500 μm and the crystal is an oxide, it is mechanically fragile and easily cracks, so strong force cannot be applied to hold the wafer.

In addition, LPE growth must be performed while rotating the wafer in order to achieve uniform film growth, and since the specific gravity of the melt is high, the substrate holder needs to be quite strong, and the material must react with the melt. For this reason, platinum (PT) is mainly used, and platinum-gold (PT-Au) alloys are sometimes used due to its hardness.

The present invention relates to the structure of such a substrate holder.

(c) Prior art and problems FIG. 1 shows a conventional structure of a substrate holder.

Here, an alumina rod with a diameter of about 8 mm is inserted into the upper cap 1 and fixed with a platinum wire or the like, and this alumina rod is connected to a motor to rotate the substrate holder.

Next, the board holder has a long support 2 and a short support 3.
supports the retaining rings 4 and 5,
The short strut 3 supports only the uppermost retaining ring 4, and the second and lower retaining rings are held by the long strut 2 and two support rods 6 protruding from it.

Although the substrate holder in FIG. 1 is illustrated as consisting of two holding rings, in reality, a plurality of rings having the same structure as the lower holding ring 5 are formed in series.

Further, each holding ring 4, 5 is provided with a plurality of L-shaped fixing jigs 7 (four in this embodiment) for fixing the wafer, and the wafer is attached to a Pt that extends horizontally from the holding ring. A wire or a Pt plate was used as a holding base, and the wafer was fixed by bending the vertical Pt wire or Pt plate as a claw.

Here, the retaining rings 4 and 5 are attached to the column 2.
The wafer is tilted at an angle of 10 to 15 degrees, and the reason for this is to minimize the amount of melt adhering to the wafer when the substrate holder is lifted out of the melt.

Substrate holders with such a configuration are generally used, but when setting a wafer in the substrate holder, it is necessary to work carefully because the wafer is thin and brittle, and therefore it takes time and labor to attach the wafer. It was a bad idea.

(d) Purpose of the invention The purpose is to improve the workability of fixing a wafer to a substrate holder.

(e) Structure of the device Conventionally, the wafer was fixed to the substrate holder using several fixing jigs provided on the holding ring, but the present invention uses two support holders at each stage. A notch is provided in each of the periphery of the board.
The structure is such that one or two holders are provided on each stage of the holding ring in opposition to this to fix the opposing parts around the substrate.

FIG. 2 is a side view of a substrate holder embodying the present invention, and FIG. 3 is a front view of a holding ring constituting the same.

That is, in the two long columns 8 and 9, notches 11 and 1 corresponding to the thickness of the wafer are formed adjacent to the joint between the two long columns 8 and 9 and the holding ring 10.
2 is provided. Furthermore, the same fixing jig 13 as in the prior art is provided at a position corresponding to the apex of an isosceles triangle whose base is a straight line connecting the two supports.

In other words, the method for fixing the wafer is to use the two notches 11 and 12 provided on the two supports.
This is done by bending the claws of the fixing jig 13 after inserting the wafer.

In order to stabilize the fixed wafer, it is necessary to leave a considerable distance between the two long supports 8 and 9 as shown in FIG.
It is desirable that the shape formed by connecting 3 and 3 is an equilateral triangle.

An even more stable fixing method is to install two long posts 8 at a 90° angle from the center of the retaining ring.
9, and two fixing jigs 13 may be arranged in a regular square shape as in the case of FIG.

(f) Effects of the invention This invention was made with the aim of improving the workability of fixing the wafer to the substrate holder during the LPE film growth process. On the other hand, when using the holder of the present invention, it is only necessary to insert the holder into the notches provided in the two pillars and then fix it using the claws of the fixing jig, which greatly improves work efficiency.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a conventional substrate holder for LPE film growth, FIG. 2 is a side view of the substrate holder according to the present invention, and FIGS. 3 and 4 are front views of a holding ring. In the figure, 2, 8, and 9 are long struts, 3 is a short strut, 4, 5, and 10 are retaining rings, 7 and 13 are fixing jigs, and 11 and 12 are notches.

Claims (1)

[Scope of utility model registration request] A substrate holder that performs epitaxial growth on a plurality of single-crystal thin-layer substrates by holding them in a layered manner and immersing them in a high-temperature solution,
The substrate is secured by a notch provided in each step of the two supports of the holder, and one or two holders provided opposite to the notch on the retaining ring of each step. A substrate holder for LPE film growth, characterized in that: is fixed thereto.