JPH05217902A - Heat treating apparatus - Google Patents

Abstract

PURPOSE:To suppress mixture of impurities with a material to be treated so as to heat-treat the material to be treated such as a semiconductor wafer, etc. CONSTITUTION:All or only surfaces of a heat-treating furnace 4, a susceptor 6, a shaft 5 and a gas inlet tube 1 near the furnace 4 are formed of nickel or a material containing nickel as a main ingredient. More particularly, such a structure can be formed of a nickel-plated member, for example, of stainless steel. The furnace 4 is heated therein to a predetermined temperature by a heater 3, SiHCl3, H2 gas are introduced into the furnace 4, and a wafer W is, for example, CVD-treated. Then, hydrogen chloride gas is generated by heat-treating decomposition and recombination, but even if the gas is brought into contact with the inner surface of an apparatus, no impurity is generated therefrom.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment apparatus for semiconductor wafers and the like, and more particularly to materials for heat treatment furnaces and the like.

[0002]

2. Description of the Related Art In order to obtain a device from a semiconductor wafer, various steps are combined and repeated,
Among them, heat treatment such as CVD and etching is an important step along with lithography. In this type of heat treatment apparatus, a large number of wafers are normally housed in a heat treatment furnace made of quartz or stainless steel, and the inside of the heat treatment furnace is heated to about 800 ° C. by a heater, and a gas supply pipe made of stainless steel is provided. The processing gas is introduced through the heat treatment, and the heat treatment is performed while maintaining a predetermined degree of vacuum.

[0003]

By the way, recently, as DRAMs are aiming for a large capacity transition from 4M to 16M, 32M and further, high integration of devices has been attempted at a rapid pitch. There is.

In order to achieve high integration of such a device, more severe conditions are imposed on each process than ever before, and even in the heat treatment, the purity of the processing gas, the etching selection ratio, the impurities on the wafer, and the like. Further improvement is required for adhesion of substances, and factors that have not been taken up until now have been considered.

The present invention has been made under such circumstances, and an object thereof is an apparatus capable of suppressing the mixing of impurities into the object to be processed when the object to be processed such as a semiconductor wafer is heat-treated. To provide.

[0006]

According to the present invention, as one of the factors for attaining high integration of a semiconductor device, the factor of the contamination of impurities into the wafer during the heat treatment is only the impurities originally contained in the processing gas. However, we have found that it is related to the material of the heat treatment furnace itself, which is not currently focused on as a source of impurities, and even if the factor is not so problematic at the present degree of integration, so-called next-generation It is understood that the influence is high in highly integrated devices, and the present invention selects the material of the heat treatment apparatus based on concrete data.

[0007] That is, the present inventor pays attention to stainless steel which is a material of the heat treatment furnace, which is considered to have no problem in generation of impurities at present, and as shown in Examples to be described later, the stainless steel is actually extremely high in a heating atmosphere. When contacted with a pure hydrogen halide gas and microanalyzed in the gas, it was found that Fe was contained in an amount that would be a pollution source for the production of, for example, 32M DRAM, but nickel (Ni)
I found that it was not included.

In etching, which is one of the heat treatments, a hydrogen chloride (HCl) gas is usually used as a processing gas, and in a film forming process such as CVD, a gas containing hydrogen and halogen such as SiH ₂ Cl ₂ , SiHC
is often used like l _3, in this case the thermal decomposition hydrogen and chlorine recombine some hydrogen chloride generated, the hydrogen chloride is to dislodge the impurities that adhere to the crystal surface. However, if the amount of impurities in the surroundings is large, the amount mixed in the film will be large as a result. Therefore, in the present invention, in such a heat treatment apparatus, the portion which is in contact with the processing gas and is heated is made of a material containing nickel as a main component. Therefore, in the present invention, for example, when heat-treating a semiconductor wafer, impurities are not generated from the apparatus or can be suppressed as much as possible, so that impurities are suppressed from being mixed into the object to be processed.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, for example, a barrel type CV shown in FIG.
It can be applied to the D device. This apparatus is configured by providing a wafer susceptor 6 which is rotated by a vertical shaft portion 5 in a barrel-shaped heat treatment furnace 4 in which a gas introduction pipe 1 and an exhaust pipe 2 are connected and a heater 3 is arranged outside. For example, all or only the surfaces of the heat treatment furnace 4, the susceptor 6, and the shaft portion 5 are made of nickel or a material containing nickel as a main component.

Specifically, such a structure can be achieved by nickel-plating the surface of a molded body made of, for example, stainless steel.

The inside of the heat treatment furnace 4 is heated by the heater 3 to, for example, about 800 ° C., and SiHCl ₃ and H _{2 are} added.
A gas is introduced into the heat treatment furnace 4 to perform CVD on the wafer W.
When the treatment is carried out, hydrogen chloride gas is generated by thermal decomposition and recombination, but when hydrogen chloride gas comes into contact with the inner surface of the apparatus, no impurities are generated from here.

Next, in order to support this, an experiment conducted to investigate the desorption behavior of the component metals from the stainless steel in a hydrogen atmosphere or a hydrogen-hydrogen chloride atmosphere will be described. 1. Sample preparation A round bar made of stainless steel SUS316 and having a diameter of 300 mm was cut with a lathe to a thickness of 10 mm to form a columnar shape, which was polished with emery paper # 800. Then this 60
A sample was prepared by immersing it in a 5% H ₂ SO ₄ aqueous solution heated to ℃ for 3 minutes for etching, washing with ultrapure water, drying with alcohol, and then leaving it in a petri dish for about 15 hours. did. 2. Metal desorption test As shown in FIG. 2, the sample S is placed in the quartz tube 7 set in the electric furnace 71, heated to a predetermined temperature, and then hydrogen gas and hydrogen chloride gas are supplied at 750 ml and 18 ml per minute, respectively. And flow through the quartz tube 7. After holding this state for 30 minutes, hydrogen gas exhausted from the lower end of the quartz tube 7 is passed through the exhaust tube 8 to the ultra-high purity IN hydrochloric acid aqueous solution in the trap container 9 to trap the accompanying metal, After concentrating this hydrochloric acid aqueous solution, Fe, Ni, Cr
Was quantified.

The hydrogen used was one that passed through a molecular sieve (5A; using a drying tube manufactured by GL Sciences) and a membrane filter (0.015 μ manufactured by NUCLREPORE).

Such an experiment was carried out when the temperature inside the quartz tube 7 was 20.
The results shown in Table 1 were obtained when the same experiment was performed under the conditions of 0 ° C., 400 ° C., 600 ° C., and 800 ° C. and the case where only hydrogen gas was flown without flowing hydrochloric acid gas. ..

[0015]

[Table 1] For each temperature condition, the upper numerical values are the results when only hydrogen gas was flown, and the lower numerical values are the results when hydrogen gas and hydrogen chloride gas were flown. The unit of the numerical value in Table 1 is (μg), but only the unit of the numerical value of Fe (m in the case of flowing hydrogen gas and hydrochloric acid gas at a temperature of 800 ° C.)
g). ND is a value outside the detection limit. 3. Discussion Regarding the components of the stainless steel SUS316 used for the sample, Fe is contained in 60 to 72%, Ni is contained in 12 to 16%, and Cr is contained in 16 to 18%. On the other hand, when the sample was allowed to flow through the hydrogen gas and the hydrogen chloride gas without being placed in the quartz tube 7, 2.5 μg of Fe was collected, and Ni and Cr were not contained.

By comparing the above with the results of Table 1, the following can be understood. That is, 200 for Fe
When it is heated up to ℃, it desorbs by reacting with hydrogen gas, and when it exceeds 400 ℃, the desorption amount becomes considerably large with respect to hydrogen chloride gas, especially when it reaches 8000 ℃,
Detached on the order.

Further, Cr does not react with hydrogen gas, but desorbs with respect to hydrogen chloride gas at 800 ° C. On the other hand, Ni is not desorbed to hydrogen gas or hydrogen chloride gas. That is, it was found that Ni is usually corroded by hydrogen chloride in the presence of water, but does not react even at high temperatures in the absence of water.

Therefore, Ni is the preferred material for the device in which hydrogen chloride gas is produced during the process, and C
It is understood that r is a suitable material as long as it does not reach 800 ° C.

Of course, the present invention can be applied to the case where film formation or etching is performed on a semiconductor wafer as described above, but a halogenated gas such as hydrogen chloride gas is introduced to the surface of the object to be processed. The present invention can be applied to other processes for etching the impurities, such as an apparatus for pulling up single crystal silicon by a thermal diffusion method.

The present invention is not limited to the case where all the portions in contact with the heat treatment atmosphere are made of Ni,
For example, Ni may be used only for the heat treatment furnace,
Further, a material containing Ni as a main component may be used instead of 100% Ni.

[0021]

As described above, according to the present invention, a hydrogen halide gas is used as a processing gas, or a source of contamination of an object to be processed is provided to a heat treatment apparatus in which the hydrogen halide gas is generated during the process. Since it is taken from the viewpoint of the material and the material containing nickel as the main component is used, nickel is not released as an impurity into the processing atmosphere as evidenced by the experimental example. Pollution can be suppressed as much as possible. 3
When manufacturing a highly integrated device such as a DRAM having a large capacity of 2M or 64M, the allowable range of mixing of impurities is considerably narrow, which is extremely effective particularly when applied to such a process.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an experimental device for supporting the effect of the present invention.

[Explanation of symbols]

 1 Gas introduction tube 2 Heat treatment furnace 3 Susceptor 4 Quartz tube S Sample

Claims (1)

[Claims] 1. An apparatus for heat-treating an object to be processed using a processing gas containing hydrogen and halogen, wherein a portion which is in contact with the processing gas and is heated is made of a material containing nickel as a main component. And heat treatment equipment.