JPS6080216A - Method for epitaxial growth by molecular beam - Google Patents

Abstract

PURPOSE:To prevent contamination of a substrate surface at ion implantation or excess of In by covering surfaces of holding means in a periphery of the substrate with InAs or InSb of the same quality as the substrate. CONSTITUTION:When a substrate 1 of InAs or InSb is attached to a substrate holding means 2 by In solder, surfaces of the holding means 2 and a substrate stopper plate 3 in a periphery of the substrate to be subjected to ion irradiation are also coated with In. Further, before ion bombardment, As or Sn is evaporated from a cell for molecular beam in a vacuum to heat the substrate 1, the holding means 2 and the stopper plate 3. By such heating, In fuses so that As or Sb atoms which bumped against the holding means 2 and the stopper plate 3 fuse into the In and solid phases of InAs or InSb are deposited on the surfaces of them after cooling to a room temperature. If ion implantation is performed under this condition, there is no exposed metallic part of the holding member 2 and the stopper plate 3 within a range that the ions bump against. Accordingly, the surface of the substrate 1 is not contaminated by the metal composing the holding means 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a molecular beam epitaxial growth method for epitaxially growing crystals of the same type or different types on a semiconductor substrate by vapor deposition.

[Prior art]

In the molecular engineering/pitaxial growth method, prior to growth, it is necessary to clean the substrate surface by removing oxides and the like. To this end, conventional methods have been used to evaporate the oxide by heating at high temperatures, or to remove the oxide by evaporating the oxide by ion bombardment.

However, when using an InAs or In8b substrate, the melting point is low, so it cannot be heated to a high temperature.

Since the congruent evaporation (or sul)limation temperature (above this temperature, the V group is more likely to evaporate from the surface of the rV-V group semiconductor than the group V group), high-temperature heating methods do not remove As or sul from the cell. This has been commonly used because III is unlikely to be separated and produced on the substrate surface even if sb is evaporated.

In the molecular beam epitaxial growth method, as shown in FIGS. 1 and 2, the substrate l is made of Mo + by solder such as In.
It is attached and held by a substrate holder λ made of metal such as Ta. In addition, in some cases, after the substrate 1 is placed on the substrate holder, it is fixed to the holder 2 with the metal substrate holding plate 3 using this holding plate 3ta-visg. . Ion bombardment is performed by ionizing an inert gas such as argon, accelerating it at a voltage of 0.1-/kV, and applying it to the surface of the substrate 1.

At this time, since the ion beam irradiation range is wider than the substrate l, not only the substrate l but also the substrate holder 2 around the substrate l
The surface of the substrate holding plate 3 is also subjected to ion bombardment. For this reason, metal atoms such as Mo and Ta that constitute the holder λ, etc., and In atoms attached to the surface of the holder 2 are also knocked out, and some of them also adhere to the surface of the substrate 1. and pollute;
Alternatively, excessive In may be produced on the surface of the substrate (lσ), which adversely affects subsequent crystal growth.

〔the purpose〕

Therefore, an object of the present invention is to eliminate such drawbacks (i.e., to replace the surface of the holder etc. around the substrate with InA of the same quality as the substrate).
The object of the present invention is to provide a molecular beam epitaxial growth method in which the substrate is covered with In8b or In8b and treated appropriately.

[Structure of the invention]

In order to achieve such an objective, the present invention.

Prior to molecular beam epitaxial growth of a crystal of the same or different type as the InAs or InS b substrate, the substrate V, In? When the substrate is bonded to a substrate holding member as solder and the surface of the substrate is cleaned by ion bombardment with an inert gas, the substrate σ) is bonded to the substrate holding member in the area irradiated with ions during ion bombardment around the substrate. The surface of the holding member is covered with In, and the substrate holding member is heated in a vacuum before ion bombardment.
or sb is evaporated to cover the substrate holding member.
First, the substrate and the substrate holding member are cooled, and then the substrate is cleaned by Kion bombardment.

Note that here, the substrate holding member is /jO−≠! [Example] In the present invention, first, when a substrate made of InAs or InSb is attached to a substrate holder λ by In solder, ion irradiation σ) is applied at the time of ion bombardment. A substrate holding member around the rising substrate l, that is, a substrate holder! And also on the surface of the substrate holding plate 30? Apply and cover.

Furthermore, the holder is attached to a 2ft molecular beam epitaxial apparatus, and then, after evacuation and before ion bombardment, if an InAs substrate is used as the substrate 1, for example, A is removed from the molecular beam cell.
In the case of an InSb substrate, sb is evaporated, and the substrate 1, substrate holder 2, and substrate holding plate 3 are heated to 150~
Heat to ≠s o ”c.

Note that, since the melting point of In8b is 530°C, the upper limit of this temperature was set at ≠SO°C with a margin so that the heating temperature did not approach this melting point too much.

When heated above 750°C, In melts, so the As or sb atoms that evaporate and hit the substrate holder 2 and substrate holding plate 3 dissolve into the In, and after cooling to room temperature, the In melts. A solid phase of InAs or InSb is deposited on the surface. If ion bombardment is performed in this state, since there are no exposed metal parts of the holder 2 and the substrate holding plate 3 in the range hit by the ions, the surface of the substrate will be contaminated by the 111t4MO etc. that make up these holders 2. Never.

Yet again. Since InAs or InSb is generated on the In-coated surfaces of the holder 2 and the substrate holding plate 3, not only In but also As (or sb) is knocked out by ion bombardment of these parts. Therefore, the materials that scatter and adhere to the substrate l are also In and As.
However, by heat treatment after ion bombardment, these form the same InAs (or InSb) as the substrate 1, and there is no excessive In as in the conventional technology, and there is almost no effect on subsequent epitaxial growth. .

These effects of the present invention are more effective when the spatial distribution of the ion beam intensity is not uniform or when the beam is raster scanned.

〔effect〕

As explained above, according to the method of the present invention.

Since the substrate surface is not contaminated or In excess occurs during ion bombardment, there is an advantage that good molecular beam epitaxial growth can be performed thereon.

[Brief explanation of the drawing]

FIG. 1 is a top view showing an example of a substrate and a substrate holder, and FIG. 2 is a side view thereof. l...Substrate, 2...Substrate holder. 3... Board holding plate, ≠... screw. Patent applicant Nippon Telegraph and Telephone Corporation

Claims (1)

[Claims] 1) Prior to molecular beam epitaxial growth of a crystal of the same or different type as the substrate on an InAs or In8b substrate, the substrate '%7. When In is bonded to a substrate holding member using solder and the surface of the substrate is cleaned by ion bombardment with an inert gas, the area irradiated with ions during ion bombardment around the substrate bonded to the substrate holding member is The surface of the substrate holding member is covered with In, and As is heated while the substrate holding member is heated in vacuum before ion bombardment.
Alternatively, the Sb is evaporated and deposited on the In covering the substrate holding member, the substrate and the substrate holding member are then cooled, and the substrate is then cleaned by ion bombardment. Epitaxial growth method. 2. In the molecular beam epitaxial growth method according to claim 1, the substrate holding member +i so-HirojQ
Molecular beam epitaxial growth method characterized by heating to ℃ (margin below)