JPH0521367A - Thermal processing apparatus - Google Patents

Abstract

PURPOSE:To improve reproducibility and uniformity of electrical characteristics of an ion-implanted semiconductor by forming a trapping type holder with a cover for loading a sample with a material such as silicon, which does not allow vaporization of elements at a thermal processing temperature and ensures excellent infrared absorption coefficient, in a thermal processing apparatus of a semiconductor substrate. CONSTITUTION:Halogen lamps 1 are disposed at the upper and lower outside of a quartz glass furnace tube 2. A 3-inch GaAs substrate 3 is housed within a Si holder 4. The holder 4 is formed as a disk measuring external diameter of 125mm and thickness of 1.5mm. The holder 4 houses a substrate 3, provided with a cover 6 made of Si and is then loaded within a furnace tube 2 with support of a quartz glass pin 5. With this structure, the holder is heated by the infrared emitted by the halogen lamp 1. Namely, Si is implanted in the quantity of 1X10<13>cm<-2> to an undoped semi-insulating GaAs substrate with an implantation energy of 10keV by the surface orientation <100> LEC method at a room temperature. As a result, fuluctuation of sheet resistance can be improved in comparison with that of a graphite holder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a short-time heat treatment apparatus used for forming a conductive layer by, for example, ion-implanting a III-V semiconductor single crystal substrate and then heat-treating for a short time.

[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 the contact resistance. Although a heat treatment method that does not cause large crystal damage to the dissimilar junction is required, the short-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 involves a temperature rise (about 100 per second).
(° C.) and an extremely short heat treatment time (1 to several tens of seconds), 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 this direct heating method, the temperature of the sample can be raised and lowered quickly by infrared absorption / emission of the semiconductor. For example, it is more responsive than the indirect heating method of heating the plate on which the sample is placed with Joule heat. It is possible to perform temperature control with excellent properties.

When such a short-time heat treatment is performed, the substrate to be heat-treated is installed by supporting the substrate at three points with pins such as quartz, or by installing it on another semiconductor substrate and surrounding it with a guard ring. Although the method of enclosing and the like has been used, the method which has received the most attention today is a method in which a sample is housed in a disk-shaped holder made of graphite or the like and heat-treated (A. Tamura et al. J. Appl.P
hys. 62, 1102 (1987), S.H. J. Pea
rton & R. Caruso J. Appl. Ph
ys. 66.663 (1989)).

By using this method, the edge effect (RT Blunt et al. Ap) in which the temperature of the peripheral portion of the substrate is lower than that of the central portion due to heat radiation from the periphery of the substrate
pl. Phys. Lett. 47.304 (1985)
Temperature non-uniformity effect caused by the convection of the atmospheric gas (M. Kohno et al. J. Appl. Phy).
s. 69.1294 (see 1991)), and heat treatment with excellent uniformity can be performed.

As a temperature control method for carrying out such a large amount of heat treatment with good reproducibility, it is necessary to use a pyrometer for detecting the thermal radiation of the sample and monitoring the temperature.

[0009]

However, when the sample substrate is housed in the holder and the heat treatment is performed for a short time using the pyrometer, the measurement temperature is greatly affected by the value of the emissivity of the surface of the holder. It has been known.

In particular, when the holder is made of a material such as graphite that easily adsorbs impurities, or a material such as GaAs that easily evaporates components at high temperatures,
It is necessary to coat the surface of the holder with a substance such as SiC in order to prevent contamination by impurities during heat treatment.
It is known that when such coating is performed, the value of emissivity largely depends on the thickness and quality of the coated material.

For this reason, the reproducibility of the thickness and quality of the coating material easily affects the temperature measurement, but the process reproducibility at the time of coating is not generally sufficient, and at the same time, the factor of modification by heat treatment. It is known that the reproducibility of the emissivity is generally deteriorated when the coating is performed due to the addition of the.

In such a case, the temperature reproducibility of the holder measured by the pyrometer is lowered, and the reproducibility of the process is lowered. This is a problem that must be avoided in order to manufacture an integrated circuit with excellent yield.

Therefore, it is necessary to select, as a holder material for controlling the temperature with good reproducibility using a pyrometer, a substance having a very low possibility of contamination by impurities as described above.

However, due to differences in the infrared absorption characteristics, thermal conductivity, specific heat, density, etc. of the substrates, an instantaneous temperature difference may occur between the two, resulting in deterioration of uniformity and process reproducibility. It is known.

For example, when the infrared absorption spectrum of the holder material is much larger than that of GaAs of the sample, it is clear that the temperature of the holder tends to be higher than that of the sample during the temperature rising process by lamp heating.

In such a case, a deviation occurs between the temperature of the holder measured by a thermocouple or a pyrometer and the temperature of the sample, which deteriorates the reproducibility of the process and adversely affects the uniformity itself. This is a problem that must be avoided in order to manufacture an integrated circuit with excellent yield.

An object of the present invention is to provide a heat treatment apparatus which solves the conventional problems associated with the above-mentioned lamp heating heat treatment.

[0018]

In order to achieve the above object, the heat treatment apparatus according to the present invention is a heat treatment apparatus having a confined holder with a lid and a sample such as a compound semiconductor substrate placed in the holder. The confined holder with a lid is formed of a material such as silicon, germanium or the like, which does not evaporate components at the heat treatment temperature and has an excellent infrared absorption rate.

[0019]

When the ion-implanted III-V compound semiconductor substrate is heat-treated for a short time, it is difficult to adsorb impurities,
And the components do not evaporate at high temperature (low vapor pressure)
By placing the sample in a disk-shaped holder made of a substance such as Si crystal and performing heat treatment, the electrical uniformity and reproducibility of the ion-implanted layer is significantly improved.

The reason why the present invention greatly improves the uniformity of the heat treatment process is that it is difficult to adsorb impurities, and the components do not evaporate at high temperatures (low vapor pressure).
Since the sample is placed in a disk-shaped holder made of a substance such as i-crystal and the heat treatment is performed, there is little error in measuring the sample temperature with a pyrometer, and it is considered that the reproducibility of the process is improved.

[0021]

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, the halogen lamp 1 is arranged above and below the quartz glass core tube 2. Three
Inch GaAs substrate 3 is a Si holder (susceptor)
It is stored in 4. The holder 4 has a disk shape, and has an outer diameter of 125 mm and a thickness of 1.5 mm.

The Si holder 4 accommodates the substrate 3,
It is covered with a Si lid 6, supported by a quartz glass pin 5, and installed in the furnace core tube 2. Using the heat treatment apparatus of the present invention having the above configuration, heating was performed by infrared rays emitted from the halogen lamp 1, and the following experiment was conducted.

Orientation <100> LEC (Liquid
Encapsulated Czochralski)
Energy of undoped semi-insulating GaAs substrate 1
Si (plus) was injected at 00 KeV at 1 × 10 ¹³ cm ⁻² at room temperature. The sheet resistance variation as a result of performing the experiment 20 times or more is σRs = 7Ω / □, and the result when the graphite holder coated with SiC is used σRs =
It was found that it was significantly improved compared to 18Ω / □.

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.

In the present invention, as the holder material,
It is a material that has a high infrared absorption rate and that does not easily evaporate the constituent components of the holder at the heat treatment temperature.
In addition to Si, any substance that does not easily adsorb impurities such as germanium and whose components do not evaporate at high temperatures (low vapor pressure) can be applied. 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.

[0028]

As described above, according to the apparatus of the present invention, for example, the resistance uniformity and reproducibility in the substrate surface of the ion-implanted active layer obtained by the short-time heat treatment of the III-V group compound semiconductor can be improved. The yield can be greatly improved as compared with the conventional one, and thus the yield of the high speed integrated circuit 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]

 DESCRIPTION OF SYMBOLS 1 Halogen lamp 2 Quartz glass core tube 3 3 inch GaAs substrate 4 Holder of the present invention (made of Si) 5 Quartz glass pin 6 Lid (made of Si)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location H01L 21/26 L 8617-4M 21/324 C 8617-4M

Claims (1)

Claim: What is claimed is: 1. A heat treatment apparatus having a confinement type holder with a lid, wherein a sample such as a compound semiconductor substrate is installed in the holder, wherein the confinement type holder with the lid is made of silicon or germanium. In addition, the heat treatment apparatus is characterized in that it is formed of a material that does not evaporate the components at the heat treatment temperature and has an excellent infrared absorption rate.