JPH0722312A - Method for manufacturing strain semiconductor film - Google Patents

Abstract

PURPOSE:To provide the title strain semiconductor film having high quality and reliability by relaxing the restriction on the critical film thickness posing a problem when the strain semiconductor film is to be grown. CONSTITUTION:The second semiconductor 12 having a different lattice constant from that of the first semiconductor is formed on a substrate comprising the first semiconductor 11 in about the critical film thickness in a dual heterostructure and successively the third semiconductor 13 having the strain in the reverse direction to that of a semiconductor layer lattice-matching with the first semiconductor 11 or the second semiconductor 12 is formed. At this time, the step of forming the second semiconductor 12 is to be performed either at low growing temperature not damaging the crystallinity or making use of surfactant. Through these procedures, the title strain semiconductor layer can have high quality with the layer thickness thereof restricted to the range within about the critical film thickness in a dual heterostructure thereby enabling the excellent reliability upon element manufacturing process to be stably placed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a strained semiconductor film used in high performance semiconductor lasers and high performance electronic devices.

[0002]

2. Description of the Related Art When a semiconductor layer having a lattice constant different from that of a substrate is laminated on the substrate, the semiconductor layer is deformed by biaxial stress to form a strained semiconductor layer. In this strained semiconductor layer, the energy band structure of the valence band can be changed mainly according to the magnitude of strain and the layer thickness. Therefore, by using this strained semiconductor layer as an active layer of a semiconductor laser, for example, Higher performance such as lower oscillation threshold and faster response becomes possible. However, when a strained semiconductor layer is stacked, energy due to strain is stored in the film, and when a certain layer thickness is reached, dislocations are generated in the film or the growth changes three-dimensionally into island-shaped growth. This critical film thickness is called a critical film thickness, which is a great constraint when using a strained semiconductor. The critical film thickness is originally an amount determined by the strain amount or elastic constant of the strained semiconductor layer, but by performing low temperature growth or growth using a surfactant such as Te or Sb, the strained semiconductor layer having the critical film thickness or more is quasi It is known to form as a stable state (GJWhaley et
al.Appl. Phys. Lett. 57 , 144 (1990), N. Gramdjean et
Rev. Lett. 69 , 796 (1992)).

[0003]

In the above-described low temperature growth or strained semiconductor growth using a surfactant, a flat epitaxial film with few misfit dislocations can be stacked up to a certain layer thickness, but annealing for device fabrication, etc. This process causes strain relaxation due to the introduction of dislocations and defects in the strained semiconductor layer in the metastable state, and the strain effect initially intended disappears. In addition, strain relaxation occurs during device driving, resulting in characteristic deterioration. An object of the present invention is to provide a method of manufacturing a strained semiconductor film which is energetically stable and highly reliable.

[0004]

In the method for manufacturing a strained semiconductor film according to the present invention, the crystallinity of a second semiconductor having a lattice constant different from that of the first semiconductor is impaired on a substrate made of the first semiconductor. Low temperature growth, or growth using one of the surfactants' crystal growth method, and stacking within the critical film thickness of the double hetero structure, and continuing.
The third semiconductor layer is characterized by laminating the third semiconductor layer having either one of the structure lattice-matched with the semiconductor of 1) and the structure distorted in the opposite direction to the second semiconductor.

[0005]

The operation of the present invention will be described with reference to the drawings. Figure 2
The relationship between the strain amount f and the film thickness is shown. The dotted line in FIG. 2 shows the critical film thickness of the single hetero structure, and the solid line shows the critical film thickness of the double hetero structure. When a strained semiconductor film having a strain amount f ₁ is grown, this film reaches a critical film thickness at a film thickness h _C1 under normal growth conditions and misfit dislocations start to be introduced into the film, but low temperature growth and surfactant are not generated. By using it, it is possible to stack without causing misfit dislocations in the strained semiconductor layer even if h _C1 is exceeded. The thickness of the strained semiconductor layer is the critical thickness N _{2 of the} double hetero structure.
(This is larger than the critical film thickness of the single hetero structure), and if a semiconductor layer having the same lattice constant as that of the substrate or strain in the opposite direction to the strained semiconductor layer is successively laminated thereon, this strained semiconductor film will be formed. It becomes energetically stable, and the occurrence of misfit dislocations during the process or device driving is extremely reduced. Thus, in the present invention,
It is possible to grow a strained semiconductor layer having a high reliability with the same strain amount and a strained semiconductor layer having a larger strain amount with the same film thickness with high reliability.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a strained semiconductor film manufactured according to the present invention. A second semiconductor 12 having a different lattice constant is laminated on a substrate made of the first semiconductor 11 by low temperature growth or growth using a surfactant to a layer thickness within the critical film thickness of the double hetero structure. Subsequently, a third semiconductor 13 having the same lattice constant as the first semiconductor 11 or strain in the opposite direction to the second semiconductor 12 is laminated. In the method for manufacturing a strained semiconductor film of the present invention, there are few dislocations during growth of the strained semiconductor and the final strained semiconductor layer is energetically stable, so that the strained semiconductor layer is less deteriorated during the process or device driving. The restrictions on device design due to the critical film thickness have also been greatly improved.

Embodiments of the present invention will be described below with reference to specific examples.

FIG. 3 is a process chart in the case where the second semiconductor layer which is a strained semiconductor is grown at a low temperature. A GaAs layer 32 of 1000 liters is laminated on a GaAs substrate 31 having a (100) plane orientation by a molecular beam epitaxial method. The growth temperature at this time is 600 ° C., the growth rate is 0.7 μm / h,
The As pressure was 1 × 10 ⁻⁶ Torr. Then, when a strained semiconductor layer having an In composition of 0.3 is grown, the growth temperature is 550
The critical film thickness of the single heterostructure is about 30Å at about ° C. Here, the growth temperature is lowered to 460 ° C., and low-temperature growth InGa having a critical film thickness of the double hetero structure of about 60 Å
The As layer 33 is laminated. At this time, misfit dislocations and three-dimensional island-shaped growth were not observed by RHEED observation even if the thickness exceeded 30 Å, and a coherent strained semiconductor layer having high flatness was formed. Subsequently, while increasing the growth temperature to 600 ° C., the GaAs cap layer 34 is laminated to 1000 Å. No morphology such as crosshatch or slip line is observed on the surface, and the low temperature grown InGaAs layer 33 is in a completely distorted state from the photoluminescence spectrum, and the full width at half maximum and the strength are both good and there are no defects. A strained semiconductor layer having a small number of layers is formed. Moreover, even if this strained semiconductor film is annealed in an As atmosphere at 650 ° C. for 1 hour,
It can be seen that the surface morphology does not change and the photoluminescence spectrum does not change from that before annealing, and this strained semiconductor film is thermally stable.

FIG. 4 is a process diagram in the case where a second semiconductor layer which is a strained semiconductor is grown by using a surfactant. The GaAs layer 42 is laminated on the (100) plane GaAs substrate 41 by the molecular beam epitaxy method to 1000 Å. The growth temperature at this time is 600 ° C, and the growth rate is 0.7μ.
The m / h and As pressure were 1 × 10 ⁻⁶ Torr. Next Te
A single atomic layer of atoms is irradiated onto the GaAs layer 42 to Te.
The atomic layer 43 is formed. After slightly lowering the growth temperature to 550 ° C., an InGaAs layer 44 having an In composition of 0.3 is laminated by 60 Å. Even in this case, the RHEED is a streak even after the growth of the 60 Å InGaAs layer 44, and a strained semiconductor layer having high flatness can be obtained without dislocation or three-dimensional island formation. Then, at a growth temperature of 500 ° C., In composition 0.4, InGa
The P layer 45 is laminated by 300Å. The InGaP layer 45 has a lattice constant smaller than that of GaAs and has a strain in the opposite direction to the InGaAs layer 44. The strained semiconductor film produced in this manner has the same good surface morphology and photoluminescence spectrum as in the above-mentioned examples, and is also excellent in thermal stability.

In the above embodiments, InGaAs / GaA is used.
Although the s series was used as an example, this is InGaAsP /
Even InP-based, InGaP / GaAs, SiGe
It may be a / Si system. The surfactant used may also be Sb, As, Sn.

In this embodiment, InGaA is used as the strained semiconductor layer.
Although a single layer composed of s is used for the description, in the present invention,
Even if this strained semiconductor layer is composed of a plurality of layers, the same effect can be obtained. In this case, as the lattice constant of the strained semiconductor layer, the strain amount based on the average lattice constant in consideration of the layer thickness of the plurality of layers forming the strained semiconductor layer may be used.

[0012]

According to the present invention, a strained semiconductor film having a high quality and a high reliability can be formed by significantly relaxing the critical film thickness, which is a constraint condition on the growth when the strained semiconductor film is used. It is possible to improve the performance of a strained semiconductor quantum well laser, a hetero bipolar transistor, etc. using the same.

[Brief description of drawings]

FIG. 1 is a sectional view of a strained semiconductor film according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram for explaining the operation of the present invention.

FIG. 3 is a first of the present invention for growing a second semiconductor layer at low temperature.
Process drawing of the embodiment of FIG.

FIG. 4 is a process drawing of a second embodiment of the present invention in which a second semiconductor layer is grown by using a surfactant.

[Explanation of symbols]

 11 First Semiconductor 12 Second Semiconductor 13 Third Semiconductor 31 GaAs Substrate 32 GaAs Substrate 33 Low Temperature Growth InGaAs Layer 34 GaAs Cap Layer 41 GaAs Substrate 42 GaAs Layer 43 Te Atomic Layer 44 InGaAs Layer 45 InGaP Layer

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[Procedure amendment]

[Submission date] September 21, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

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Claims (1)

[Claims] 1. A low temperature growth of a second semiconductor having a lattice constant different from that of the first semiconductor on a substrate made of the first semiconductor, or a growth utilizing a surfactant. One of the crystal growth methods is used to determine whether the structure is stacked within the critical film thickness in the double hetero structure and is subsequently lattice-matched with the first semiconductor or is distorted in the opposite direction to the second semiconductor. A method for manufacturing a strained semiconductor film, comprising laminating a third semiconductor layer having any one of the structures.