JPS622521A - Molecular beam epitaxial device - Google Patents

Abstract

PURPOSE:To produce a crystal with excellent quantity by measuring and controlling accurate temperature of a substrate by a method wherein a radiothermometer and a black body radiative source are arranged on positions symmetric with a perpendicular drawn on the surface of a substrate to control the temperature of black body radiative source and the substrate independently. CONSTITUTION:When a substrate 2 is mirror-reflected, the calories Q per unit area measured by a radiothermometer 8 are represented by the reflection between the temperature TW of substrate 2 and the temperature TB of a black body radiative source 10. The temperature TB of black body 10 is measured by a thermocouple 11. Therefore, when the temperature TB of another black body radiative source 11 is independently fluctuated in two ways by a heater 13 and the respective calories Q are measured by the radiothermometer 8, the temperature TWof substrate 2 and the emissivity epsilon can be calculated. Through these procedures, the absolute temperature of substrate 2 can be measured making it feasible to control the output froml another heater 5 by means of feeding back the absolute temperature thus measured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a molecular beam epitaxy apparatus, and particularly to a molecular beam epitaxy apparatus suitable for accurately controlling the temperature of a substrate.

[Background of the invention]

Conventionally, temperature control of the substrate in molecular beam epitaxy equipment has been carried out in accordance with [Molecular Beam Epitaxy Equipment Technology] (Kogyo Kenkyukai, 1.
984) is known. To explain with reference to FIG. 3, in the vacuum container 1, the substrate 2
and is attached to the sample rotation holder 4.

A heater 5 for heating the substrate 2 and a thermocouple 6 for measuring the temperature of the substrate 2 are fixed to the sample rotation holder 4.

The tip of the thermocouple 6 cannot come into contact with the rotating susceptor 3.

It is fixed near the center of the susceptor 3. Since such an installation structure does not allow absolute measurement of temperature, the indicated value of the thermocouple 6 is calibrated with a radiation thermometer 8 through the window 7 of the vacuum container 1 at any time.

The temperature of the substrate 2 is controlled by feeding back the indicated value of the thermocouple 6 and controlling the output of the heater 5 with the temperature regulator 9.

However, in the temperature measurement and control method with the above configuration, the molecular beam 10 flying from the single molecular beam cell attaches to the surface of the substrate 2, and the weight of the substrate 2 changes, causing the overall thermal balance to collapse. The relative relationship between the temperature of the substrate 2 and the indicated value of the thermocouple 6 is no longer constant, and the correct temperature of the substrate 2 cannot be measured. Therefore, there was a problem that temperature control was not possible.

Furthermore, the temperature of the substrate 2 is not measured by the thermocouple 6.

Even if the temperature is measured using a radiation thermometer 8, accurate temperature measurement cannot be performed because the weight of the substrate 2 changes over time. The purpose of this invention is to provide a molecular beam epitaxy device that can accurately measure and control the temperature of a substrate.

[Summary of the invention]

The molecular beam epitaxy apparatus of the present invention takes advantage of the specular reflection property of the substrate and arranges a blackbody radiation source and a radiation thermometer at symmetrical positions with respect to the perpendicular to the substrate surface. The temperature of the substrate surface can be detected by using a radiation thermometer to detect the amount of heat from the blackbody radiation source reflected on the substrate surface and the amount of heat radiated from the substrate surface. In addition, the temperature can be accurately controlled to the crystal growth temperature.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be explained with reference to FIG.
The same symbols as in the figure indicate the same parts.

In FIG. 1, 11 is a black body radiation source, 12 is a thermocouple that measures the temperature of the black body radiation source 11, 13 is a heater that heats the black body radiation source 11, and 14 is a perpendicular line drawn to the surface of the substrate 2. The radiation thermometer 8 and the fish body radiation source 11 are arranged symmetrically with respect to this perpendicular 14 so as to form an angle of 0. Note that 15 is a molecular beam cell for generating the molecular beam 10, 16 is a vacuum pump for evacuating the inside of the vacuum container 1, and 17 is a thermal pair for measuring the temperature of the blackbody radiation source 11.

In the above configuration, when the substrate 2 is completely specularly reflected, the amount of heat Q per unit area detected by the radiation thermometer 8 is
is expressed by the following equation.

Q=t・σT,'+ (1-t)・aT@'
-(1) Here, E is the weight t of the substrate 2, Tw is the temperature I of the substrate 2, TR is the temperature of the blackbody radiation source 10, and σ is the Stefan-Boltzmann constant. Temperature T of black body radiation *10
, are values measured by the thermocouple 11. Therefore, if the temperature T of the blackbody radiation source 11 is independently changed in two ways by the heater 13, and the amount of heat Q at that time is set to 41 by the radiation thermometer 8, then from equation (1), the temperature T of the group Fi2, It is possible to obtain the tofu weight ε. In this way, it is possible to measure the absolute temperature of the substrate 2 and control the output of the heater 5 by feeding back this temperature.

Note that instead of changing the temperature T of the blackbody radiation source 11 using the heater 13, as shown in FIG.

A chopper 18 is provided between the black body radiation source 11 and the substrate 2, the temperature of the black body radiation source 11 is kept constant, and the chopper 18 is rotated to calculate the amount of heat i・σT w' radiated from the surface of the substrate 2 and the black body radiation source 11. Even if the amount of heat radiated from the body radiation @11 and reflected on the surface of the substrate 2 (1-g) ・σT,4 and the sum of the amount of heat ε・σTw4 radiated from the substrate surface are detected separately, the amount of heat emitted from the substrate 2 is Surface temperature T.

and weight C can be measured.

Next, when the cross-weight ε of the substrate 2 changes with time as during crystal growth, the temperature Tll of the blackbody radiation source 11
is changed by the heater 13 and set equal to the set temperature (crystal growth temperature) T□ of the substrate 2. Between the set temperature T,ll of the black body radiation source 11 and the set temperature TV,l of the substrate 2, as in both equations (1) when the weight does not change, Q2ε・σTWll'+(1-ε)・σT,,'-(2
) holds, and here T. = T, A, so Q = σTw
a'=σT1.4... (3
), and the amount of heat Q detected by the radiation thermometer 8 becomes equal to the amount of heat radiated by the blackbody radiation source 11, regardless of the weight ε of the substrate 2. In other words, when the temperature of the black body radiation source 11 is set to the temperature of the substrate 2 to be set, the amount of heat Q detected by the radiation thermometer 8 is equal to the amount of heat σT radiated by the black body radiation source 11.
By changing the output of the heater 5 so that it becomes equal to wa' or σT, 4, accurate temperature control of the substrate 2 becomes possible.

Next, FIG. 3 shows a block diagram of a control system that independently controls the temperature of the substrate 2 and the blackbody radiation source 11. The set values T□ and T□ of the substrate temperature and the blackbody radiation source temperature are set in advance in adjustment 11i)9.

The respective temperatures are detected by the radiation thermometer 8 and the thermocouple 17, and the deviations from the set values T, , T□ are Δ'r,.

The heater 5°1 is controlled by the output signal from the regulator 9 by AT, l.
The temperature is controlled by changing the output of step 3. At this time, the amount detected by the radiation thermometer 8 is the amount of heat Q, so 1
The temperature T is calculated using equation (1) or equation (3).

Therefore, the blackbody radiation source temperature T is also fed back to the temperature calculation section of the substrate temperature control system.

In addition, in the above invention, the same effect can be obtained even if a radiation thermometer that detects a specific wavelength or wavelength range is used instead of the radiation thermometer 8 to detect the radiation resistance strength in this wavelength or wavelength range. Needless to say.

〔Effect of the invention〕

As explained above, according to the present invention, the radiation thermometer and the blackbody radiation source are arranged in symmetrical positions with respect to the perpendicular line drawn on the substrate surface, and the temperature of the blackbody radiation source and the substrate temperature are controlled independently. By doing this, it is possible to accurately measure and control the temperature of the substrate not only when the weight of the substrate is constant, but also when the weight of the substrate changes over time. This has the effect that it can be obtained.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of the molecular beam epitaxy apparatus of the present invention, Figure 2 is an explanatory diagram of another embodiment of the molecular beam epitaxy apparatus of the present invention, and Figure 3 is an illustration of temperature control in the molecular beam epitaxy apparatus of the present invention. Block diagram of the control system. FIG. 4 is an explanatory diagram of a conventional molecular beam epitaxy apparatus. DESCRIPTION OF SYMBOLS 1... Vacuum container, 2... Substrate, 5, 13... Heater, 8... Radiation thermometer, 11... Black body radiation source, 17
...Thermocouple, 18...Chopper.

Claims (1)

[Claims] 1. In a molecular beam epitaxy device that detects the temperature of the substrate surface and irradiates the substrate with molecular beams to achieve epitaxial growth while controlling the heating temperature of the substrate, A black body radiation source and a radiation thermometer are disposed, and the temperature of the substrate and the temperature of the black body radiation source are independently controlled, and the radiation thermometer measures the amount of heat emitted from the black body radiation source and reflected on the substrate surface. 1. A molecular beam epitaxy apparatus characterized by being configured to measure the temperature of the substrate surface by detecting the amount of heat radiated from the substrate surface and to control the temperature of the substrate surface. 2. In the apparatus according to claim 1, the means for independently controlling the temperature of the substrate and the temperature of the black body radiation source measures the temperature of the substrate and adjusts the heater with the regulator to control the temperature of the substrate. It consists of a substrate temperature control system that controls the temperature, and a blackbody radiation source temperature control system that measures the temperature of the blackbody radiation source and controls the temperature of the blackbody radiation source by adjusting the heater with a regulator. A molecular beam epitaxy apparatus that controls the heating temperature of a substrate while feeding back the temperature of a blackbody radiation source to a calculation unit that calculates the temperature.