JPH0774115B2 - Liquid phase epitaxial growth method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Overview] Regarding a liquid-phase epitaxial growth method, a substrate is rotated and moved after the epitaxial growth, and a residual melt adhered on the substrate is dropped to a lower portion by a wipe-off to adhere to the substrate when the epitaxial growth is stopped. For the purpose of providing a liquid phase epitaxial growth method in which the contact area of the residual melt is reduced, the epitaxial growth substrate is supported by a fixing jig enclosed in an ampoule, and the epitaxial growth substrate is melted by being accommodated under the substrate. Rotate the ampoule to the melt to bring it into contact with the substrate, grow the epitaxial crystal on the substrate while lowering the temperature of the melt, and then rotate the ampoule again to drop the melt remaining on the substrate. In the method for growing an epitaxial crystal, the substrate is melted. After the epitaxial crystal is grown by contacting with the melt for the axial growth, the substrate is rotated to temporarily stop the rotation of the ampoule immediately before the substrate is separated from the melt, and then the rotational speed is the rotational speed before the stop of the ampoule. The ampoule is further rotated at the following predetermined rotation speed to separate the substrate from the melt.

[Industrial application field]

 The present invention relates to a liquid phase epitaxial growth method.

A compound semiconductor crystal such as mercury, cadmium, tellurium (Hg _1-x Cd _x Te) having a narrow energy band gap is used for a photoelectric conversion element such as an infrared detection element or an infrared laser element.

When such a Hg _1-x Cd _x Te crystal is epitaxially grown on a cadmium (CdTe) substrate, mercury is an easily evaporative element, so use an ampoule with a closed structure to prevent evaporation of mercury and melt it. The gradient type liquid phase epitaxial growth system that forms the epitaxial layer on the substrate by bringing the melt of Hg _1-x Cd _x Te into contact with the substrate has a simple device structure and good composition controllability of the formed epitaxial layer. It is often used for such reasons.

[Conventional technology]

As shown in FIG. 3, a conventional liquid phase epitaxial growth apparatus has a groove 3 for sandwiching a substrate holder 2 holding an epitaxial growth substrate 1, and accommodates an epitaxial growth melt 4 melted when the apparatus rotates during epitaxial growth. It is composed of a pair of opposed cylindrical fixing jigs 6 each having a space 5, and an ampoule 7 for enclosing the fixing jig 6.

A case where an epitaxial layer is formed on a substrate by a conventional method using such a conventional liquid phase epitaxial growth apparatus will be described.

As shown in FIG. 4 (a) of the sectional view taken along the line III-III ′ of FIG. 3, the substrate 1 is set on the substrate holder 2, and the substrate holder 2 is attached to the groove 3 of the fixing jig 6 described above. Installed inside the substrate 1
The fixing jig 6 in which is installed is sealed in the ampoule 7 in a state where the melt forming material 4 for epitaxial growth made of mercury, cadmium and tellurium is filled in a position on the opposite side facing the substrate.

Next, the ampoule 7 is connected to a furnace core tube (not shown) in a heating furnace.
Then, the ampoule 7 is heated to melt the melt-forming material 4 in the ampoule 7.

Then rotate the ampoule 7 by 180 degrees along the direction of arrow A,
As shown in FIG. 4 (b), the melted epitaxial growth melt 4 is brought into contact with the substrate 1, and the temperature of the heating furnace is lowered to lower the temperature of the melt 4 and the saturated vapor pressure corresponding to the lowered temperature. An epitaxial layer is deposited and formed on the substrate by bringing a saturated melt having the above into contact with the substrate.

Then, further rotate the ampoule 7 in the direction of arrow B by 180 degrees,
The epitaxial growth is stopped by tilting the substrate and finally in a state as shown in FIG. 4 (a) to wipe down the melt adhering on the substrate to the lower part.

[Problems to be Solved by the Invention]

However, in the above method, after growing the epitaxial layer on the substrate, the substrate is rotated 180 degrees from the surface of the melt,
When the molten melt adhering to the substrate is dropped to the lower part, as shown in FIG. 5, this molten melt becomes spherical due to the surface tension and spreads to become the residual melt 4A. The melt 4A enters from the peripheral edge 1A of the epitaxial growth substrate 1 to the inside of the substrate, and when this residual melt 4A is solidified, it appears as a protrusion on the epitaxial layer formed on the substrate, and therefore the epitaxial layer There is a problem that the area that can be used as an element decreases.

The present invention eliminates the above-mentioned problems, allows the residual melt to move to the peripheral portion of the epitaxial layer, and prevents the melt from entering the element formation region of the formed epitaxial layer, thereby making the area of the epitaxial layer usable for the element. It is an object of the present invention to provide a liquid phase epitaxial growth method capable of taking a large amount.

[Means for Solving the Problems]

The liquid phase epitaxial growth method of the present invention for achieving the above object is to support an epitaxial growth substrate with a fixing jig enclosed in an ampoule, and rotate the ampoule into a melt for epitaxial growth that is accommodated under the substrate and melted. Then contact the substrate, and while growing the epitaxial crystal on the substrate while lowering the temperature of the melt,
In a method for growing an epitaxial crystal by rotating the ampoule again to drop the melt remaining on the substrate, the substrate is brought into contact with the melt for epitaxial growth to grow the epitaxial crystal, Immediately before the substrate is separated from the melt by rotating the substrate, the rotation of the ampoule is temporarily stopped, and then the rotational speed is set to a predetermined rotational speed equal to or lower than the rotational speed before the ampoule was stopped, and the ampoule is further rotated. It is constructed so that the melt is separated.

[Work]

The method of the present invention, the substrate is brought into contact with the molten melt and epitaxially grown to rotate the substrate, and immediately before the substrate is separated from the melt surface, the rotation is stopped and the residual melt at the peripheral portion of the substrate is utilized by utilizing the surface tension of the melt. Make sure it falls to the bottom. Furthermore, by lowering the rotation speed of the substrate from this position to a predetermined rotation speed that is lower than the rotation speed before stopping the rotation of the substrate, it is possible to prevent the melt from being scooped again onto the substrate from the peripheral portion of the substrate. Then, even if the residual melt remains on the substrate, a small amount remains,
Prevent the residual melt from entering the element formation area.

〔Example〕

An embodiment of the present invention will be described in detail below with reference to the drawings.

1 (a) to 1 (c) are explanatory views of the liquid phase epitaxial growth method of the present invention.

As shown in FIG. 1 (a), CdTe is placed on the substrate holder 2 described above.
After setting the substrate 1 for epitaxial growth of, the substrate holder 2 is fitted into the groove 3 of the fixing jig 6, and the melt 4 for epitaxial growth is set in the space of the fixing jig 6,
The fixing jig 6 and the melt are enclosed in an ampoule 7, and the ampoule is inserted into a heating furnace to melt the melt.

Then, as shown in FIG. 1 (b), the ampoule 7 is rotated 180 degrees in the direction of the arrow C to bring the molten melt 4 into contact with the substrate 1, and then the temperature of the melt 4 is lowered so that the molten melt 4 is placed on the substrate. An epitaxial layer of melt component is formed. The steps up to this point are the same as the conventional method.

Next, the ampoule 7 is further rotated along the direction of arrow D from 130 to 140 degrees at a rotation speed of 3 degrees per second, and immediately before the peripheral edge portion 1A of the substrate 1 is separated from the melt 4 as shown in FIG. 1 (c). When the position reaches, stop the rotation of the ampoule and
Let stand for 10 to 60 seconds to ensure that the melt adhering to the peripheral edge of the substrate falls to the bottom.

Then, the ampoule 7 is further rotated along the direction of arrow E at a rotation speed not more than 1/2 of the rotation speed before stopping the ampoule, that is, 40 to 50 degrees at a rotation speed of 1 degree per second, and FIG.
Set to the state of (a).

Such rotation speed can be adjusted by attaching a quartz rod to the ampoule sealing portion, further attaching a gear to the quartz rod, and adjusting the rotation speed of a motor for rotating the gear.

By doing so, the peripheral edge portion 1A of the substrate does not scoop up the melt again on the substrate, and the residual melt 4A is accumulated in the peripheral edge portion 1A of the substrate in a very small amount as shown in FIG. Since it does not enter the formation region of the detection element, a large number of detection elements can be formed with a high yield from one substrate.

〔The invention's effect〕

As is clear from the above description, according to the method of the present invention, since the residual melt after wiping off remains in the peripheral portion of the substrate in a trace amount, the element formation region of the epitaxial layer can be made large, and infrared detection can be performed. This has the effect of reducing the manufacturing cost of the device.

[Brief description of drawings]

1 (a) to 1 (c) are sectional views showing a liquid phase epitaxial growth method of the present invention, FIG. 2 is a plan view of a substrate formed by the method of the present invention, and FIG. 3 is a conventional liquid. 4 (a) to 4 (b) are sectional views showing a conventional liquid phase epitaxial growth method, and FIG. 5 is a plan view of a substrate formed by the conventional method. In the figure, 1 is a substrate for epitaxial growth, 1A is a peripheral portion of the substrate, 2 is a substrate holder, 3 is a groove, 4 is melt for epitaxial growth, 4A is residual melt, 5 is a space, 6 is a fixing jig, and 7 is an ampoule. Show.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kosaku Yamamoto 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa, Fujitsu Limited (72) Inventor Ho Yamamoto 1015, Ueda-anaka, Nakahara-ku, Kawasaki, Kanagawa

Claims (1)

[Claims] 1. An epitaxial growth substrate (1) is supported by a fixing jig (6) enclosed in an ampoule (7), and an ampoule (4) is contained in a molten epitaxial growth melt (4) housed under the substrate. 7) is rotated to bring the substrates into contact with each other, and an epitaxial crystal is grown on the substrate while lowering the temperature of the melt, and then the ampoule is rotated again to drop the melt remaining on the substrate. In the method for growing an epitaxial crystal, the substrate (1) is brought into contact with a molten epitaxial growth melt (4) to grow an epitaxial crystal,
Immediately before the rotation of the ampoule (7) is stopped immediately before the substrate is separated from the melt by rotating the substrate, the rotation speed is set to a predetermined rotation speed lower than the rotation speed before the rotation of the ampoule was stopped, and the ampoule is further rotated. A liquid phase epitaxial growth method comprising rotating a substrate to separate the substrate (1) and the melt (4).