JPS6177733A - Pressure measuring device - Google Patents

Abstract

PURPOSE:To reduce the turbidity of components due to a sensor part, by the constitution, wherein the inner side surface of a tubular body through which fluid flows, becomes pressure sensors, which are moved in concave and convex shape in accordance with the pressure of the fluid, and both lower surfaces of the tubular body become input and output ports of said fluid. CONSTITUTION:A pressure measuring device has a circular cylinder shape. One lower surface of the circular cylinder is made to be an input port 1 of gas, and the other lower surface is made to be an output port 2 of the gas. The side surfaces of the circular cylinder are made to be metal diaphragms 5, which are fixed by two ring shaped fixing parts 9 and 10. An airtight chamber 8 is provided so as to surround the metal diaphragms 5. Electrodes 6 are provided so as to face the metal diaphragms 5 in the inside. Thus a pressure sensor is formed. Therefore the side surface of the tubular body of the pressure sensor is moved in the concave and convex shapes in accordance with the pressure of the fluid. Both lower surfaces are made to be the input and output ports of the gas and the inside of the tube is made to be the pressure measuring device. Thus stagnation is not present in the measuring chamber and turbidity is not yielded because the entire gas is replaced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a pressure measuring device for creating gas pressure in a semiconductor crystal vapor phase growth apparatus or the like.

(Prior Art and its Problems) The vapor phase growth method as a method for growing semiconductor crystals involves feeding a gaseous raw material into a crystal growth chamber and growing a semiconductor crystal from the gaseous raw material. It is necessary to measure the gas pressure in order to control the amount of gas phase raw material in the gas flow, control the flow direction of the gas, and control the pressure in the crystal growth chamber.

Conventionally, a structure shown in FIG. 4 (al) or FIG. 4 (bl) has been used for such pressure measurement.

FIG. 4(a) is a sectional view of what is known as a Bourdon tube pressure gauge. This principle has been known for a long time,
For example, there is an explanation on page 1183 of the 3rd edition of the Physical and Chemistry Dictionary published by Iwanami Shoten (published in 1971). This Bourdon tube pressure gauge is
An arc-shaped or spiral-shaped metal tube made of a thin elastic full-cover plate, with a flat cross section, one end 33 closed and the other end 34 connected to the area 32 where the pressure is to be measured. 31. The closed end 33 of this spiral metal tube is connected to another metal plate 3 by a gold A4 rod 35.
6 at a fixed point 17.

When the pressure in the measured region 32 is p1, the Bourdon tube pressure gauge becomes the metal tube 31 shown by the solid line.

The pressure in this measurement area 32 is a higher pressure p2 than the pressure p1.
At the time of
become. spiral metal tube 31 when the pressure is pl
becomes a spiral metal tube 31' shown by a broken line when p2, and the closed end 33 is at the position of the end 33' Fi:, ilC
By moving and pulling the metal rod 35, the metal plate 3
6 moves and comes to the position of the metal plate 36'. Here, by measuring the amount of displacement of the metal plate 36 and the distance Δxt between the measuring point 37 and the measuring point 37' of the tab 9, the pressure p2 can be measured using F) spl as a reference.

Moreover, FIG. 4(b) shows a sectional view of the capacitance pressure gauge.

This measures the displacement of a metal plate due to pressure changes using changes in capacitance. One section of the cylindrical cavity 41 is connected to a metal diaphragm 42, and the bottom surface of the pond is connected to a pressure measurement area 44 through an opening 43. The airtight chamber 45 in which a certain amount of gas is sealed includes a metal diaphragm 42 and an electrode 46 facing the metal diaphragm 42 . This electrode 46 and metal diaphragm 4
The capacitance between the two metal plates varies depending on the distance between the two metal plates. The solid line in FIG. 4(b) shows the state when the pressure in the region 44 to be measured is a certain pressure p1. When the pressure in this pressure measurement area 44 is changed from pl to I)2(+)2>1)1), the position changes from the diaphragm 42 shown by the solid line to the diaphragm 42' shown by the broken line.

As a result, the distance between the diaphragm 42 and the electrode 46 changes, and the capacitance changes. By measuring the change in capacitance in this way, the pressure p2 with respect to s91 is
can be known.

There are several other gas pressure measurement techniques, but all of them involve guiding gas from the pressure measurement area to the pressure measurement area and collecting it in the 2-3 cavities inside the pressure gauge. The structure is such that the pressure is measured using the gas that is present.゛Figure 5 shows the conventional pressure gauge
One configuration diagram used for OVPE) is shown.

Graphite susceptor 22 arranged in quartz growth chamber 21
Hold the G a A S board 23 on top and attach the RF coil 24
Growth is performed by heating the substrate 23. Arrows P, C, D, and J indicate the flow direction of trimethylaluminum (TMA), hydrogen (H2), methylgallium (TMG), and arsine (AsH3), respectively, and 11 to 16 indicate 17 shows a stop valve, and 17 shows a needle valve. By opening and closing these valves 11 and 12, the flow of 9TMA is switched in the direction of arrow E or F. The flow to arrow B is the flow where TMA is discarded to the bypass line, and the flow to arrow F is the flow where TMA is discarded to the growth chamber 2.
There is a flow that is introduced into 1 and used for growth. Similarly, the TMG is switched between the flow H to the bypass line and the flow G to the growth chamber 21 by the valves 13 and 14. Furthermore, AsH3 is switched by valves 15, 16 into a flow L to the bypass line and a flow K to the growth chamber 21. Arrow I indicates a flow containing carrier gas H2 and organometallic raw materials TMA and TMG, which heads toward the growth chamber 21, and arrow M indicates a flow containing A s H3 to this flow, which leads to the growth chamber 2.
This is the flow introduced in 1. Further, the waste turtles that have completed one reaction are removed from the growth chamber 21 as indicated by arrow N. The pressure gauges 25 and 26 measure the pressure of the mixed gas of TMA, TMG, and H2, and the pressure of the growth chamber 21, respectively.
These are of conventional construction. Further, the needle valve 17 is used to adjust the pressure of the carrier gas containing organic metal based on the measured value of the pressure gauge 25.

Using such a growth apparatus, AλX () a 1-
An example of forming a beta structure in which an X As (0<x<1) layer and a GaAs layer are grown in this order will be described. First, with valves 11 closed, 12 open, 13 open, 14 closed, 15 open, and 16 closed, TMA, TMG, and AsH3 are introduced into the growth chamber 21 together with carrier gas H2 to grow AλxGal XAS. After the growth of the AixGal-xAs layer is completed, the valve 11 is opened and the valve 12 is closed to stop the flow of TMA, and the process begins to grow GaAs. At this time, the pressure gauges 25 and 26 indicate AλxGaI XA! 1 during growth, % T M A stagnates inside the pressure gauge, and T
TM remained stagnant inside the pressure gauge even after the flow of MA was stopped.
A gets mixed in with the flow of arrow 1 and arrow M for a while, and reaction tube 2
1, the flow of TMA does not stop abruptly.

An example of the heterostructure interface obtained in this way is the sixth
It will look like the composition distribution diagram in the figure. That is, in FIG. 6, the horizontal axis shows the distance in the thickness direction in units of λ, and the vertical axis shows the molar composition of l of the epitaxial layer and the molar composition of Ga as AJI x
These are shown for the Ga□-XAs layer and the GaAs layer, respectively. From the figure, it can be seen that the range of participants performing the transition area is large, ranging from 500 to 750, approximately 250 people.

The presence of such a thick transition region not only causes defects in properties when creating normal heterostructure elements, but also poses a fatal drawback when creating ultrathin film structures such as quantum wells and superlattice structures. Become. In addition, in the case of a heterostructure of materials in which lattice matching shifts when the composition shifts, anomalies at the interface have a large effect. Furthermore, profile irregularities at the interface of impurity doping have a large adverse effect on device characteristics. In addition, when the growth system is exposed to the atmosphere and the atmosphere is introduced into the pressure gauges 25 and 26, the atmosphere accumulated in the pressure gauges is not easily replaced with inert gas and becomes a source of contamination. The drawback is that it takes a long time to reach a suitable state.

(Object of the Invention) The object of the present invention is to eliminate such conventional drawbacks and to provide a method for growing high-quality semiconductor epitaxial layers and multilayer epitaxial layers with good quality interfaces by applying it to a vapor phase crystal growth apparatus. It is an object of the present invention to provide a pressure measuring device which is suitable for various cases and which causes less turbidity of components due to the sensor portion.

(Structure of the Invention) The structure of the pressure measuring device of the present invention is such that the inner surface of a cylindrical body through which fluid flows is uneven according to the pressure of the fluid, and both bottom surfaces of the cylindrical body are It is characterized in that an inlet and an outlet are formed between the inlet and the outlet and the cylindrical body in a streamlined shape, and the pressure inside the cylindrical body is measured.

(Embodiment) FIG. 1 is a sectional view of an embodiment of the present invention, showing a cylindrical pressure gauge. One bottom surface of this cylindrical tube is designated as a gas inlet 1, and the other bottom surface is designated as a gas outlet 2.

The side surface of this cylinder is a metal diaphragm 5 fixed with two annular fixing parts 9 and 10.

An airtight chamber 8 is formed surrounding this metal diaphragm 5.
An electrode 6 is provided inside thereof facing a metal diaphragm 5, and serves as a pressure sensor.

The capacitance between the metal diaphragm 5 and the metal electrode 6 depends on the distance between them. When the pressure in the pressure measurement chamber 7 is pl, the metal diaphragm 5 is in the state of the metal diaphragm 5 shown by the solid line, but when the pressure in the pressure measurement chamber 7 is high, the pressure p2 (p
z>px), the metal diaphragm 5 as shown by the broken line
9. As the distance between the diamond 72 and the electrode 6 changes, the capacitance value changes. By measuring the value of this capacitance, the pressure in the pressure measurement chamber 7 can be determined. In this embodiment, the gas inlet from arrow A and the gas outlet from arrow B have streamlined structures 3 and 4 that do not cause flow turbulence. With such a structure, there is no part where gas accumulates, and the gas to be measured for pressure does not stay inside the pressure gauge, so that the gas inside the pressure gauge can be replaced quickly. 1ζ When the type of gas flowing inside the pressure gauge changes from the state in which a flow is formed by the gas inside the pressure gauge and its pressure is measured, the next gas displaces the first gas.
Therefore, gas exchange is quick.

On the other hand, a pressure sensor consisting of a metal diaphragm 5 and an electrode 6 measures the pressure of the new flow.

Even if this pressure measurement chamber 7 is not a cylinder but a polygonal cylinder, the effect remains the same. With this configuration, the inner surface of the cylindrical or polygonal cylinder becomes a pressure sensor, and both bottom surfaces become the gas intake and outlet, respectively, and the inside of this cylinder becomes a pressure measuring device, so pressure can be measured. A pressure measuring instrument having a structure in which all the gas is quickly replaced without stagnation inside the room can be obtained.

FIG. 2 shows a configuration diagram when the pressure gauge of this embodiment is applied to MOVPE. This figure shows a pressure gauge 1 in place of the pressure gauges 25 and 26 used in the conventional configuration shown in Figure 5.
8.19 was established. These pressure gauges18.19
are the pressure of the TMA-TMG/H2 mixed gas, respectively,
This device measures the pressure in the growth chamber 21, and has the structure of the embodiment shown in FIG. 1, and the pressure of the gas to be measured is measured by causing the gas to be measured to flow inside the pressure gauge. In the growth apparatus shown in FIG. 2, as in FIG. 5, AAxGax-xAa
(When forming a veterinary structure in which a 0 (x < 1) layer and a GaAs layer are sequentially grown, the pulp is controlled to open and close the inflow of TMA into the growth chamber 21. In this case, the pressure gauge 18
9 has a different structure from the conventional structure, and since there is no part where gas accumulates, the TMA quickly flows away, and this TMA
The flow of MA is abruptly stopped.

Therefore, the heterostructure interface obtained is steep as shown in the distribution diagram of FIG. In Figure 3, the horizontal axis shows the distance in the thickness direction * in units of , and the vertical axis shows the molar composition of AfL and the molar composition of Ga in the epitaxial layer A x G
a 1-zA a layer and GaAsjiiVc are respectively shown. As shown in this figure, it can be seen that when this example is used, a configuration in which the width of the transition region is as small as 10 Å or less can be obtained. For this reason, double heterostructure lasers and high-transition′! It becomes possible to obtain good characteristics in a heterostructure element such as a 1JJ transistor, and it also becomes possible to obtain an ultra-thin film structure with good characteristics.

Furthermore, even if the growth system is exposed to the atmosphere and the atmosphere is introduced into the pressure gauges 18 and 19, by purging the inside with inert gas, the atmosphere accumulated in the pressure gauges can be quickly expelled. The source of contamination can be removed.

Note that this example uses AJ! by vapor phase growth. xGa1-XA
Although we have explained the formation of S-based heterojunction, AJGaInP
It can be applied to the vapor phase growth of semiconductors such as the growth of InGaAsP-based and InGaAsP-based compounds. Further, although this embodiment has been explained using gas, it is obvious that it can also be applied to fluids such as liquids.

(Effects of the Invention) By applying the present invention, it is suitable for a vapor phase growth apparatus that grows high-quality semiconductor epitaxial layers and multilayer epitaxial layers with good quality interfaces, and no fluid remains in the senna part and mixes. A pressure measuring device with less turbidity of components can be realized.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view of an embodiment of the present invention, FIG. 2 is a configuration diagram showing how to use the embodiment of FIG. 1, and FIG. 3 is a composition of a heterostructure interface formed using this embodiment. Distribution diagram, Figures 4(a) and 4(b) are sectional views showing two sides of a conventional pressure measuring device, Figure 5 is a configuration diagram of the conventional example shown in Figure 4 when used, and Figure 6 is a diagram showing the configuration of the conventional pressure measuring device. FIG. 3 is a composition distribution map of a heterostructure interface obtained from the figure. In the figure, 1... Gas inlet, 2... Gas outlet, 3
, 4... streamline structure, 5.5', 42
．． 42'...Metal diaphragm, 6.46...
... Electrode, 7 ... Pressure measurement chamber, 8.45.
...Airtight chamber% 9,10...Ring shaped fixing part, 11-16...Pal 7', 17...
Needle pulp, 18.19°25.26...
...Pressure gauge, 21...Growth chamber, 22...
・Susceptor, 23...Substrate, 24...
RF coil, 31.31'... spiral metal tube,
32, 44... Pressure measurement area, 33.33
'...Metal pipe closed end, 34...Metal pipe connection end, 35...Metal rod, 36.36'
...Metal plate, 37.37'...Measurement point, 41...National policy Z diagram - Thickness direction pressure 1 屹 (A) Horse 3 Figure 4 figure

Claims (1)

[Claims] The inner surface of the cylindrical body through which the fluid flows becomes a pressure sensor that is uneven according to the pressure of the fluid, and both bottom surfaces of the cylindrical body serve as the inlet and outlet of the fluid, and the connection between these inlets and outlets and the cylindrical body A pressure measuring device characterized in that a gap is formed in a streamlined shape and measures the pressure inside the cylindrical body.