JPH02184023A - Glow discharge precipitation method of multilayer structure - Google Patents

Abstract

PURPOSE: To provide a multi-layer structure body without changing the composition of a gas mixture during deposition in a single reactor by using the gas mixture composed of the two kinds of gases selected from silane, germane, hydrocarbon and a gas containing nitrogen, changing a voltage applied to the electrode of the reactor during a deposition process and not changing the other parameters. CONSTITUTION: The reactor is deaerated while maintaining the temperature at 250 deg.C and then, the mixture of the germane and the silane is filled into the reactor. Then, the relative ratio of raw materials diluted by hydrogen beforehand is about germane 20% and silane 80%. The conditions are maintained fixed during the deposition. During discharge for about ten minutes, the layer of a Ge-Si alloy (for instance, the atom ratio of Ge: 0.4 and the atom ratio of Si: 0.6) is deposited. When about ten minutes elapses, the voltage at the electrode is reduced to about 400V, it is applied for about ten minutes further and the Ge-Si layer (the atom ratio of Si and Ge: 0.5) is obtained. Then, by alternately changing the voltage applied to the electrode between 1200V and 400V and keeping for a fixed time while the voltage is maintained at one of the values, the cyclic multi-layer structure body of Ge0.4 Si0.6 Ge0.5 Si0.5 is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION A method of manufacturing an amorphous material structure comprising: by plasma deposition in the gas phase. Such a structure may be, for example, J, 1. Edited by Pankove [Semiconductors and Semiconductors and Semiconductors
enimetals) JVol, 21. part,
C, p, 407. Academic Press
(NY) 1984, has applications in electronic and optoelectronic devices.

Currently, these multiphase structures are manufactured by glow discharge by varying the flow rate of the gas flow supplied to the reaction chambers, or by moving the substrate from one reaction chamber to another, and by moving the substrates from one reaction chamber to another. It is common for a certain predetermined gas mixture to be present in either one of the two. between the electrodes,
The gas is dissociated by applying an alternating voltage (frequency 108 to 10'Hz) with a peak-to-peak value of 103 to 10''V.

The former method creates hydrodynamic perturbations in the gas flow that require waiting until complete stabilization before deposition of each layer can occur, while the latter method requires non-negligible intervals to transfer the sample from chamber to chamber. exists.

These drawbacks are overcome by the present invention. The method according to the invention allows multilayer structures to be produced in a single reactor without changing the composition of the gas mixture during the deposition.

According to this, the present invention includes silicon, carbon, oxygen, nitrogen,
Silane, silane,
A gas mixture consisting of two gases belonging to different classes selected from germane, hydrocarbons, nitrogen-containing gases (e.g. nitrogen, dinitrogen pentoxide and nitrogen dioxide, ammonia) is used: applied to the electrodes of the reactor. The voltage is varied during the deposition process to induce a controlled dissociation of the gases making up the mixture and to deposit successive layers of silicon, carbon, oxygen, nitrogen, germanium, hydrogen with a controlled composition. The present invention relates to a glow discharge deposition method for multilayer structures, characterized in that all other reactor presetting parameters (pressure, raw material flow rate, and substrate temperature) are not changed during various depositions.

By appropriately setting the intervals during which the voltage is kept constant, the thickness of the layers can be controlled as desired, while the composition of each layer can be varied by appropriately choosing the value of the voltage applied to the electrodes. be able to. Accordingly, in this method, multiple layers of amorphous material are deposited by means of a plasma to form, inter alia, the structures described below.

St+-I Gem S1+-y Ge, Slt-m
Go, ””Sx, -w Cx Sg-y c, 5
is-* Cm...5ll-1N*Si, □Ny
511-m L...Sg-Ilo, 511-y
Oy S1t-m O*...(Here, x, y,
z is a mutually different number, and is from 0 to 1. ) If it is desired to obtain a doped layer instead of an intrinsic layer, a doping gas such as phosphine, arsine or diborane is added to the binary mixture.

It is also possible to dilute the binary mixture using inert gas or hydrogen.

Furthermore, if the change in the voltage applied to the electrodes is not sharp and the voltage changes uniformly in the increasing or decreasing direction over time, layers with compositional gradient ends or doping gradient ends can be produced.

The variation of the electrode potential is carried out within the range of 100 to 100 OOV. Under suitable conditions, the voltage variation over time is 10
It ranges from 0 to 2000V.

Depending on the intended use of the multilayer structure in electronic or optoelectronic devices, various substrates can be used on which these structures are deposited, such as glass or glass coated with metal oxides or metals.

The following examples are intended to further illustrate the invention, but the invention is not limited thereto.

Example 1 To measure the atomic composition as a function of film thickness, a substrate consisting of a thin silicon plate (size: 40×40×0, 3 mm) was used. This substrate was introduced into a reactor for plasma deposition and purified as described below.

The inside of the precipitation chamber is under reduced pressure of 10-' Torr or more,
Hydrogen at a pressure of 300 mTorr was supplied at a flow fi of 20 sec (standard cm" per minute). The support was heated to 250° C. and the electrodes were heated by discharging in hydrogen while supplying an alternating current of 1200 V peak-to-peak. Cleaned for 10 minutes.

When the discharge for purification is finished, the temperature is increased to 250℃.
The reactor was degassed while maintaining the germane (
A mixture of G13H4) and silane (Sin4) was charged into the reactor at a total flow rate of 20 sec and a pressure of 100 mTorr. Note that all of these gas raw materials were diluted in advance with hydrogen at a dilution ratio of 1·1O. The relative proportions of the raw materials fed are 20% germane and 80% silane.

These conditions were applied during precipitation (precipitation was performed at 13.56 MHz).
A voltage of 1200 V is applied to the electrodes by a radio frequency generator that transmits
) and kept constant. During a 10-minute discharge, a germanium-silicon alloy with a thickness of approximately 1000 m (atomic proportion of germanium: 0.
4. A layer with an atomic proportion of silicon: 0.6) was deposited. 1
At the end of 0 minutes, the value of the voltage at the electrodes was reduced to 400 μ and this voltage was applied for a further 10 minutes. In this way, a germanium-silicon layer with a thickness of 700 mm (atomic ratio of silicon and germanium: 0.5) was obtained.

The Geo 4
A periodic multilayer structure (thickness approximately 1 μII+) of Sio, a G (3o, ++ Sia, sa) was obtained.

At the end of the precipitation, the sample was cooled and removed from the reactor.

The composition of the deposited layer, determined by Auger analysis as a function of thickness, is shown above the graph in FIG.

The vertical axis shows the proportion of silicon or germanium. Line 1 relates to silicon and line 2 relates to germanium. These lines consist of 10 silicon-germanium layers whose composition alternates between 60% silicon and 40% germanium and 50% silicon and 50% germanium, from the outermost layer 3 to the layer 4 in direct contact with the substrate. This indicates the presence of an alloy layer. The final part of these lines (100% silicon
) indicates the composition of the substrate.

Below the graph in this figure, the relationship between time and electrode voltage is shown for each layer.

Example 2 The substrate was cleaned and processed under the same conditions as in Example 1 above.

However, in this example, a silane-methane mixture (370 mTorr pressure) was used as the reactant gas at a total flow rate of @20 s.
It was supplied in ccm. The relative proportions of the mixture are 40% methane and 60% silane.

Film growth was initiated by applying a voltage of 1300 V to the electrodes for 10 minutes. Under these conditions, the thickness of approximately 8
A layer of 0.00 silicon carbide (atomic proportion of carbon: 0.1°, atomic proportion of silicon: 0.9) was obtained.

A silicon layer of about 400 was then obtained by reducing the voltage to 600v and maintaining this value for 15 minutes.

By repeating this operation four more times, Si. . C
(+, ISI! multilayer structure (approximately 6000 people) was obtained.

As in Example 1, the Auger spectrum as a function of thickness is shown in FIG. In this figure, line 1 pertains to silicon and line 2 pertains to carbon. Code 3 indicates the outermost layer;
4 indicates a layer in direct contact with the substrate. The lower part of the graph in FIG. 2 shows the value of peak-to-peak voltage as a function of time.

The charts showing composition as a function of thickness do not agree in relation to the voltage-time chart, and the two materials making up the structure exhibit mutually different growth rates (i.e. layer thickness versus growth time). ratio).

[Brief explanation of the drawing]

FIGS. 1 and 2 are graphs showing the operating conditions for implementing the manufacturing method of the present invention and the composition of the obtained multilayer structure.

Claims (1)

[Claims] 1. In a glow discharge method in which a large number of amorphous layers of various compositions containing silicon, carbon, oxygen, nitrogen, germanium, and hydrogen are deposited, silane, germane, hydrocarbon,
A gas mixture consisting of two gases belonging to different classes chosen from nitrogen-containing gases (e.g. nitrogen, dinitrogen pentoxide and nitrogen dioxide, ammonia) is used; the voltage applied to the electrodes of the reactor is controlled during the deposition process. to induce a controlled dissociation of the gases constituting said mixture and to precipitate successive layers of silicon, carbon, oxygen, nitrogen, germanium, hydrogen with controlled compositions; during the various precipitations. ,
A method for glow discharge deposition of multilayer structures, characterized in that all other reactor presetting parameters (pressure, feed flow rate and substrate temperature) remain unchanged. 2. The method of claim 1, wherein a doping gas is added to the reactant gas mixture. 3. The method of claim 1, wherein the reactant gas mixture is diluted with an inert gas. 4. A method for glow discharge deposition of a multilayer structure according to any one of claims 1 to 3, wherein the voltage applied to the electrodes is gradually increased over time. 5. The method according to any one of claims 1 to 3,
A glow discharge deposition method for multilayer structures that gradually reduces the ability of the electrode to apply voltage over time. 6. The method according to any one of claims 1 to 6,
The voltage applied to the electrode is 100 to 2000V,
Glow discharge deposition method for multilayer structures.