JPH05243240A - Heat treating apparatus - Google Patents

Abstract

PURPOSE:To obtain an apparatus in which a temperature irregular effect due to generation of a Benard convection is suppressed and a heat treatment can be executed in a high uniformity for a short time by setting a product of a cube of a distance between a sample substrate and a wall of an upper core tube, a gravity constant, a volume expansion coefficient, a temperature difference of the substrate and the wall of the tube to a special value or less. CONSTITUTION:A heat treating apparatus has a core tube 2, and sets a product of a cube of a distance between a sample substrate 3 mounted in a core tube 2 and a wall of the upper tube, a gravity constant, a volume expansion coefficient, a temperature difference of the substrate 3 and the wall of the tube, a reciprocal of kinematic viscosity coefficient of atmospheric gas 5 and a reciprocal of a temperature conductivity of the gas 5 to 1700 or less. For example, a halogen lamp 1 is disposed above.below an exterior of the tube 2, and a 3-inch GaAs substrate 3 is supported by a pin 4 made of quarts glass. A distance between the substrate 3 and the wall of the upper tube of the board 3 is set to 5mm, and the gas 5 is N2 to satisfy conditions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention has excellent uniformity and reproducibility of electrical characteristics when a conductive layer is formed by, for example, ion-implanting a III-V semiconductor single crystal substrate and then heat treating for a short time. The present invention relates to a short-time heat treatment apparatus capable of obtaining a conductive layer.

[0002]

2. Description of the Related Art In recent years, as the development of high-speed digital integrated circuits using III-V compound semiconductor materials has progressed, the importance of the short-time heat treatment method has been increasing. That is, in the manufacturing process of heterojunction devices such as heterojunction bipolar transistors and heterojunction field effect transistors, ion implantation is performed for the purpose of reducing contact resistance. A heat treatment method that does not cause large crystal damage to the dissimilar junction is required, and the shortest time heat treatment method is currently the most suitable method for this purpose.

This short-time heat treatment method is also suitable for forming a shallow and high-concentration operating layer which is important for enhancing the performance of the field effect transistor. It is known that, by using this method, not only the redistribution of impurities in the operating layer can be suppressed, but also a high electrical activation rate can be obtained.

The short-time heat treatment method has a rapid temperature rise (about 1 second per second).
Heat treatment time (1 to several tens)
Second), an efficient sample heating method is required. Therefore, for example, when heat-treating a semiconductor substrate, a method of directly irradiating infrared rays from a vertical direction of a sample with a halogen lamp or the like has been generally used.

According to such a direct heating method, it is possible to rapidly raise and lower the temperature of the sample by absorbing and radiating infrared rays from the semiconductor. For example, an indirect heating method of heating the plate on which the sample is placed with Joule heat. It is possible to perform temperature control with more excellent responsiveness as compared with.

When such a short time heat treatment is performed, Ar is used to prevent the sample from being oxidized by O ₂ in the atmosphere at a high temperature.
It is common practice to use an inert gas such as (argon), N ₂ (nitrogen), H ₂ (hydrogen) as an atmosphere.

Further, by performing the heat treatment for a short time in the atmosphere gas in this way, the oxidation of the sample can be prevented, and the heat conduction efficiency between the sample support or the susceptor and the sample can be remarkably improved. It is possible to perform heat treatment with excellent temperature uniformity.

[0008]

However, when the annealing is performed for a short time in the atmosphere gas as described above, an irregular gas flow may occur in the furnace core tube. Such a gas flow is generated in a cell shape between the sample heated to a high temperature and the furnace core tube wall having a relatively low temperature above the sample, and is called a Benard flow. The generation of the Benard flow can be a cause of lowering the in-plane temperature uniformity of the sample during the short-time annealing, and is therefore a problem to be avoided in order to manufacture an integrated circuit with excellent yield.

It is an object of the present invention to provide a heat treatment apparatus for the lamp heat treatment as described above, which suppresses the temperature non-uniformity effect due to the generation of Benard convection, and performs highly uniform heat treatment.

[0010]

To achieve the above object, in a heat treatment apparatus according to the present invention, there is provided a heat treatment apparatus having a furnace core tube, wherein a sample substrate installed in the furnace core tube and a furnace core above it. Cube of distance to tube wall, and gravitational constant,
The product of the coefficient of body expansion, the temperature difference between the sample substrate and the furnace core tube wall above it, the reciprocal of the kinematic viscosity coefficient of the atmospheric gas, and the reciprocal of the thermal conductivity of the atmospheric gas is 1700 or less.

[0011]

It has been reported that if convection of atmospheric gas occurs during heat treatment and the uniformity of the sample temperature is reduced, it may cause defects such as slip lines and warpage in the crystal (Ko.
hno et al. J. Appl. Phys. 69 1
294). It is considered that such conspicuous temperature nonuniformity is largely due to the irregular flow called Benard flow among convection.

Benard convection is generated when the heated atmospheric gas near the sample tries to rise due to buoyancy. Difference, viscosity of atmospheric gas,
It is known to depend on the value of.

That is, the value of the product of two dimensionless numbers called Grashof number and Prandtl number is an index for the generation of Benard convection. The product of the Grashof number and the Prandtl number is the cube of the distance between the sample substrate and the furnace core tube wall above it, and the gravitational constant and the body expansion coefficient, and the sample substrate and the furnace core tube wall above it. It is the product of the temperature difference, the reciprocal of the kinematic viscosity of the atmosphere gas, and the reciprocal of the temperature conductivity of the atmosphere gas. It is empirically known that when this value is about 1700 or more, a Benard flow is generated (JP Holma.
n, HEAT TRANSFER, Mcgraw Hi
ll). The present invention provides a highly uniform heat treatment, which is provided with a condition that can avoid such a Benard flow generation condition.

[0014]

EXAMPLES Examples of the present invention will be described in detail below. FIG. 1 is a diagram schematically showing a device configuration of an embodiment of the present invention.

In the figure, a halogen lamp 1 is arranged above and below the quartz glass furnace core tube 2. Three
The inch GaAs substrate 3 is supported by pins 4 made of quartz glass. Distance 5 between the substrate 3 and the furnace core tube wall above the substrate
mm, atmosphere gas is N ₂ . Such a structure satisfies the condition that the occurrence of Benard convection can be avoided.

The following experiment was conducted using the apparatus having the above-mentioned configuration. Plane orientation <100> Liquid Enc
updated Czochralski (LE
C) method After implanting Si (plus) into an undoped semi-insulating GaAs substrate at an injection energy of 100 KeV at 1 × 10 ¹³ cm ^-2 at room temperature, using the heat treatment apparatus shown in FIG.
Heat treatment was performed at 00 ° C. for 5 seconds. As a result, the variation in the obtained active layer sheet resistance is σRs = 5Ω / □, and N
_This is significantly improved compared to the result σRs = 20Ω / □ when the heat treatment is performed in a _two- gas atmosphere using a heat treatment apparatus having a distance between the substrate and the furnace core tube wall above the substrate of 15 mm.

Regarding the size of the substrate, the apparatus of the present invention is effective for any size other than the 3-inch diameter used in this embodiment.

From the above, it was confirmed that by using the heat treatment apparatus of the present invention, heat treatment with excellent uniformity can be performed with good reproducibility.

[0019]

As described above, according to the device of the present invention, the resistance uniformity in the substrate surface of the ion-implanted active layer obtained by, for example, the short-time heat treatment of the III-V group compound semiconductor is made higher than that of the conventional one. Can be significantly improved, and therefore
The yield of high-speed integrated circuits can be greatly improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram schematically showing a device configuration of an embodiment of the present invention.

[Explanation of symbols]

1 Halogen lamp 2 Quartz glass furnace core tube 3 3 inch GaAs substrate 4 Quartz glass pin 5 Atmosphere gas (N ₂ )

Claims (1)

[Claims] 1. A heat treatment apparatus having a furnace core tube, wherein the cube of the distance between the sample substrate installed in the furnace core tube and the furnace core tube wall above it, the gravitational constant, and the body expansion coefficient, and A heat treatment apparatus characterized in that the product of the temperature difference between the sample substrate and the furnace core tube wall above it, the reciprocal of the kinematic viscosity coefficient of the atmospheric gas, and the reciprocal of the temperature conductivity of the atmospheric gas is 1700 or less.