JPS5957999A - Method for growing crystal - Google Patents

Abstract

PURPOSE:To prevent the deformation and surface roughening of a substrate, by carrying out the epitaxial growth of a crystal on the substrate made of a semiconductor of a tertiary compound contg. a primary element having higher vapor pressure as one constituent element after holding the substrate in an atmosphere of a secondary element having lower saturation vapor pressure than the primary element. CONSTITUTION:A boat 7 is essentially provided with a substrate 8 made of a semiconductor of a tertiary compound contg. a primary element having higher vapor pressure such as P as one constituent element, e.g., an InP semiconductor and a carbon basket 5 filled with molten Sn 10 contg. solubilized InAs contg. As as a secondary element having lower vapor pressure than P. The boat 7 is put in a quartz tube and heated. As having lower saturation vapor pressure in the molten Sn 10 is first evaporated, and the substrate 8 is held in an atmosphere contg. As vapor.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to epitaxial growth using a compound semiconductor containing an element having a high vapor pressure as a constituent element as a substrate.

InGaAsP-based semiconductors are widely used as materials for light-emitting light-receiving elements for optical communications. These multiplication tables/light receiving element f
- is generally applied to liquid phase or vapor phase Evita Kinyal growth method.
It is often produced from I↓J by crystal growth. By the way, 4'71 of the emitted light of a semiconductor laser
Various structures have been proposed in the past in order to provide a filter effect (wavelength selectivity) in the light receiving element for controlling the i7-mode or the ld longitudinal mode.

The structure of such an element is obtained by performing crystal growth on a complexly processed substrate, but during crystal growth, this substrate is left in the city while the melt is sufficiently melted. . As a result, in a substrate using InP or InGaAsP, there is a problem that the P component in particular dissolves, resulting in roughening of the surface of the substrate and deformation of the portions subjected to complicated force.

For example, in a 1i return type laser (hereinafter abbreviated as DF'B laser), in order to achieve a single longitudinal mode, the light emitting layer or a layer close to the C1 source light layer is provided with circumferential Jυ1 irregularities. Shin'N
It is formed along the force direction VC, and the unevenness provides selectivity of the oscillation wavelength. To be specific, n1iisuIn
Periodic unevenness with a period of 2360A and a diameter of about 1000A is formed on a P substrate, and an n-type 1nGaAsP layer (λ
g - 13 μm, λg: wavelength relative to the forbidden band width) with a thickness of 0.1 pm, an undoped InGaAsP layer (λg =
1. ．． 55 μm) to 0.1 μm, undoped InGaAs
PJW (λg=1.3μm) is 0.1μm, p-type In
If a laser is manufactured using a wafer on which a P layer is formed to a thickness of about 2 μm and a current is injected, a laser that oscillates in the Roux longitudinal mode at 1.55 μlη can be obtained. The threshold of this oscillation mainly depends on the height of the unevenness, or because the uneven surface is left for about an hour at a high temperature during crystal growth, the uneven surface may become rough or deformed, or in the worst case, the unevenness may disappear. It often disappeared and disappeared. The same thing happens even when left in ambient air containing sufficient P components, so this not only causes P to be released from the surface, but also minimizes the surface energy of uneven parts. It is thought that the phenomenon in which such a reaction between the solid phase and the gas phase occurs and the In and P in the image area move to the concave area is also occurring at the same time.

Unfortunately, a similar problem occurred with the light receiving element mentioned above.

Conventionally, in order to prevent the above-mentioned problems, PI (3 gas) was used or f n P crystal was used as a cut into two plates. It is difficult and rare to find +'J< I)j.

The present invention has the following advantages: (2) Suppressing cross-travel phenomenon under solid phase-gas phase and starting crystallization) 1. The purpose of the present invention is to provide a crystal growth method that prevents deformation of the microfabricated portion even in the case of "1".

A feature of the present invention is that a desired '-1
<In the epitaxial/dial crystal growth method for growing a conductor layer, the third compound semiconductor base &
is housed in an atmosphere containing a second element having a lower saturated vapor pressure than the first element.

Hereinafter, the present invention will be explained in detail by taking as an example an InP compound matte board in which P is the first element, and As is the second element.

The figure shows the recesses of a graphite boat for crystal growth.

Bow 1- has melt reservoirs 1, 2, 3.4 and J
It consists of a boat body 7 in which a cavity 6 is formed for accommodating scales 1 and 5, and a substrate holder 9 that accommodates an InP substrate 8 and is slidable when attached to the boat body 7. Here, a Sn melt 10 in which InP and InAs are dissolved is put into the carb basket 5. Each component is, for example, 5 g of Sn, 150 mg of InP + 50 mg of InAs, or 5 g of Sn. dl 1, 2, and 3.4 are filled with melt depending on the growth composition. For example, 11 is n-type InGa.
Melt for AsP layer (λg-], 3 pm), 12 is non-Dog InGaAsP layer (λg = ]-, 55 μm
), 13 is an undoped InGaAsP layer (2 g
14 is a melt for p-type InP layer.
<t. Now, in the actual crystal growth process, after the substrate, melt, etc. are all placed in a boat, it is put into a quartz tube, the temperature is raised to about 620°C while H2 gas is flowing, and the temperature is left for about 30 minutes. After <iiu~14 becomes sufficiently uniform, the temperature is allowed to drop, and the substrate 8 is sequentially brought into contact with the melt to form crystals of desired composition and film thickness. Do long. Now,
Prior to contact between the substrate and the melt, the substrate 8 is held under the carbon basket 5. The P component evaporated from the Sn melt 10 reaches the substrate holder 9 through the holes at the bottom, and serves to protect the P component from dissipating from the InP substrate surface. Furthermore, As from the same 8n melt
The As component has also evaporated, but this As component has formed an Indium component on the substrate surface.
, P, and As, and this prevents a phenomenon such as migration of In and P in the curved portion to the concave portion due to the reaction under the in-phase gas phase.

When leaving an InP substrate at a high temperature, such as with JSO soil, ■
) component and also contains an As component with a slightly lower vapor pressure.
(The protective film on the substrate surface made of As components is extremely thin, and the layer that grows directly on the substrate contains As, so the surface of the substrate can be well protected.) Because rearrangement occurs during growth, this 11ψ
has little effect on the growth layer as a whole. Such protection of the substrate cannot be achieved sufficiently with only the P component or the 1iAs component, and the oJ function can only be achieved by using both the P and As components.

For example, if the above experiment is performed using an InP substrate on which a diffraction grating of soo A and a period of 2400^ is formed,
When there was no As component, the depth was deformed to more than 50X, but when the As component was added, the depth was 300X.
The diffraction grating of grade A was well-equipped with a boat-like shape.

In the above examples, the As and P components were dissolved in the Sn melt, and metals other than Sn, such as In, Ga, PB, B1, Cd, Zn, etc. The As and P components may be dissolved in a melt of Kinmaki and used.

Also, instead of using As and P components that evaporate from the solution, InPx Asl-x or In1-y GayPx
If a single crystal wafer such as AJ-x is used as a cover for the substrate, the As and P components will be dissociated from this cover crystal, so that the same effect as when using the metal melt described above can be obtained.

As yet another method, a compound gas of As or P, such as AsH3r PH3, may be used.

In this case, l'1AsH3+PH3 decomposes at high temperatures and generates AS4°P4, etc., so a similar effect can be obtained.

Claims (5)

[Claims] (1) A substrate of a third compound semiconductor containing the first element having a high vapor pressure as one of its constituent elements. A crystal growth method comprising the step of housing the substrate in an atmosphere containing a second element at low pressure. (2) The atmosphere containing the second element contains S
n + In + Ga + P b + Bi + C
AiI” according to claim 1, characterized in that it is formed using a second element that is dissolved in a metal melt of d or Zn or a combination thereof and evaporated from the solution; Crystal growth method. (3) [The atmosphere containing the second element in Section 11J is
The compound semiconductor is formed using a second element by dissociation from a fourth compound semiconductor in which at least a part of the first element is replaced by the second element among the four constituent elements. A crystal growth method according to claim 1, characterized in that: (4) The atmosphere containing the second element is formed using the second element decomposed from a compound gas containing the second element. Crystal growth method. (5) The first element is P, and the second element is As. The third compound semiconductor is In1-xGaxA5yPl
-F (however, 042y≦χ≦o, soy, and 0≦y〈
Claim 1, characterized in that: The crystal growth method according to item 2, 3, or 4.