JPH07321061A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To improve the characteristics of an SiO2 film or the like using an IR annealing furnace, which has a very superior high-temperature and short-time controllability, in a method of manufacturing a semiconductor device, which has a process of forming an insulating film. CONSTITUTION:A method of manufacturing a semiconductor device is provided with a process of forming an insulating film, such as an SiO2 film, on a semiconductor substrate, such as an Si semiconductor substrate, in an atmosphere containing oxidizing gas or the like, such as chlorine gas, or the like, a process of heating the substrate and the insulating film in an N2 gas, O2 gas, inert gas or the like-containing atmosphere or the like by an IR heating method and a process of forming an electrode (an Al electrode or the like) on the insulating film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device. The present invention can be applied, for example, to the manufacture of memory devices, in which case the thin S required especially in recent MOS memories (DRAM, SRAM, etc.) is required.
The properties of the iO ₂ film can be significantly improved.

[0002]

SUMMARY OF THE INVENTION According to the present invention, in a method of manufacturing a semiconductor device, an insulating film is formed on a semiconductor substrate and then heat treatment is performed by IR heating, so that the film characteristics can be remarkably improved by heating for a short time. It is the one.

[0003]

2. Description of the Related Art Recent semiconductor devices, such as MOS memories, have been miniaturized, and gate oxide films and the like have become extremely thin in accordance with scaling rules.

For example, a 256K DRAM has a capacitance oxide film thickness of 100 to 120 Å, and a 1 Mbit DRAM has 8
A thin film of about 0 to 100Å is desired. The same applies to the oxide film in the SRAM cell, which is 200 Å for 256K SRAM, 1
The Mbit SRAM requires 150 Å or less.

On the other hand, in such a thin SiO ₂ film, it is extremely important to secure the breakdown voltage, and it is also important to reduce the surface level of the SiO ₂ / Si interface together with the cleaning treatment of the Si surface.

That is, it is usually 9 to form a thin SiO ₂ film.
Oxidation furnace at around 00 ° C and mixed gas of oxygen and nitrogen (O ₂ +
Although a low pressure oxidation method using N ₂ ) carrier and a low effective oxygen partial pressure is used, these oxidation methods have a problem in the denseness of an oxide film, and there is a concern that the breakdown voltage may decrease and the interface state may increase.

[0007]

As described above, a low temperature / low pressure oxidation method or the like has been studied for forming a thinner SiO ₂ film than before, but the film obtained by this method is S
It is said that SiOx bonds and unbonded Si atoms are present at the iO ₂ / Si interface, and these can cause an increase in the interface state and a breakdown voltage deterioration.

Further, although the film characteristics can be improved by the high temperature treatment, the conventional heat treatment is not suitable for a three-dimensional element or a fine MOS structure because the underlying bonding shape changes due to the long treatment time.

It is an object of the present invention to improve the characteristics of an insulating film such as a SiO ₂ film by using an IR annealing furnace which is excellent in controllability at high temperature for a short time in order to solve the above problems.

[0010]

The above object is to form an insulating film (for example, SiO ₂ ) on a semiconductor substrate in an atmosphere containing an oxidizing gas or chlorine element, and then to remove nitrogen, oxygen, and an inert gas. I in an atmosphere containing at least one
This is achieved by applying R heat treatment. IR heating may be short. The IR heating referred to in the present invention includes not only heating by a halogen lamp light or the like, but also heating of the sample by a laser beam directly applied to the sample.

The structure of the present invention is specifically outlined as follows. That is, for example, a semiconductor wafer on which an oxide film has been grown by treatment in an atmosphere containing an oxidizing gas or chlorine element to form an insulating film is uniformly irradiated with high-output halogen lamp light, etc. It can be configured to heat.

[0012]

In the present invention, the unbonded Si—O bond at the SiO ₂ —Si interface can be made into a sufficient SiO ₂ bond by subjecting the SiO ₂ film to IR heating at a high temperature after the growth of the SiO ₂ film. A semiconductor device having improved characteristics can be obtained. Further, since this IR heating can be performed in a short time, the characteristic deterioration due to the change of the underlying bonding shape, which is a problem in a three-dimensional element or a fine MOS, can be prevented.

[0013]

EXAMPLES Examples of the present invention will be described in detail below. Naturally, the present invention is not limited to the embodiments described below.

Example 1 In this example, a semiconductor substrate (here, a Si substrate) is used.
A step of forming an insulating film (here, a SiO ₂ film),
A semiconductor device was manufactured by a step of heating the semiconductor substrate and the insulating film by an IR heating method and a step of forming an electrode (here, an Al electrode) on the insulating film.

In particular, the insulating film of the examples was formed by oxidizing the surface of the semiconductor substrate with an oxidizing gas, especially in an atmosphere containing chlorine element.

Further, in the step of heating the semiconductor substrate and the insulating film by the IR heating method, the atmosphere containing at least one of nitrogen, oxygen and an inert gas (N ₂ atmosphere in this example)
Went inside.

More specifically, in this embodiment, as an experimental sample, a CZ (100) n-type substrate (2 to
3 ohm-cm), and at 1100 ° C., O ₂ + H
A gate oxide film (SiO ₂ ) of 900 Å was grown in an atmosphere of Cl (1%). Then, POA of the SiO ₂ film (Po
st-Oxidation-anneal) treatment in an N ₂ atmosphere at 1000 to 1150 ° C. for 1 second to 2 minutes
R annealing (here, halogen lamp heating) treatment was performed. After this, Al vapor deposition, metal sintering (400 ℃, 60
Min) to prepare a MOS capacitor.

In FIG. 1, the IR annealing temperature is 1000 ° C. (indicated by line III in the figure) and 1100 ° C., respectively.
(The same is shown by line I) 1150 ° C. (the same is shown by line II)
The relationship between the processing time and the surface charge Nss (cm ⁻² eV ⁻¹ ) in FIG.

As is apparent from FIG. 1, line I and line II
The Nss value of the sample according to the present invention which was subjected to the IR annealing treatment at 1100 ° C. and 1150 ° C.
It can be seen that the Nss value is lower than that of the 1000 ° C.-treated sample shown in FIG. Again 1
The Nss value of the sample according to the present invention that has been subjected to IR annealing at 100 ° C. or higher has an instantaneous Nss value of 0.6 to 1 × 10 ⁹ c.
m ⁻² eV ⁻¹ , which is reduced to ⅕ to 1/10 as compared with the sample without POA treatment (Nss = 5.9 × 10 ⁹ cm ⁻² eV), which shows the treatment time of 0. I understand.

FIG. 2 shows SiO grown as described above.
The POA treatment of the _two films was performed in an atmosphere of wet O ₂ (shown by line IV in the figure) and dry O ₂ (shown by line V in the figure).
This is a comparative example conducted in an electric furnace at 1000 ° C., but 1 × 10 ⁹
It takes more than 60 minutes to obtain Nss of cm ⁻² eV ⁻¹ , and under these conditions, the three-dimensional element junction, the well layer in the fine MOS, the channel stop region, etc. are already formed during the growth of the gate oxide film. The existing junctions were largely redistributed, and in comparison with this, the samples according to the present invention shown by lines I and II in FIG. 1 had an instantaneous Nss value of 1 × 10 ^−9.
It is clear that the film characteristics are significantly improved according to the present invention by the IR annealing treatment for a short time, which is lower than cm ^-2 eV ^-1 .

Example 2 Same as Example 1 CZ (100) n-type2-3 oh
Using m-cm Si substrate, thin SiO _{2 of} about 150Å
A film was formed. After that, in a N ₂ atmosphere, 1100 ° C., 10
FIG. 3 shows the breakdown voltage distribution when the POA treatment by IR annealing for 2 seconds was performed. As a comparative example, similar SiO
Figure 4 shows the breakdown voltage distribution of _two films that have been steam treated at 900 ° C.
It was shown to. In both FIG. 3 and FIG. 4, the horizontal axis represents the electric field applied for film destruction, and the vertical axis represents the breakdown rate. In the sample according to the present invention shown in FIG. 3, film breakdown occurs intensively in the vicinity of the breakdown electric field field of 9 to 10 MV / cm shown in (a) in the figure, and in the figure of the comparative sample shown in FIG. It can be seen that, as compared with 8.5 to 9.5 MV / cm shown in (b), it moves to the high electric field side. Further, it can be seen that the IR annealed according to the present invention shows a more concentrated concentration of the breakdown voltage distribution, and the in-plane uniformity of the wafer is improved.

The atmosphere of the IR annealing treatment is N
Other _2, in O _2, can be carried out in N ₂ + O ₂ and Ar secondary. In addition, IR heating is performed by irradiating a CO ₂ laser beam with a wavelength of 9-10 μm in addition to a high-output halogen lamp light to match the intrinsic absorption peak of Si—O with SiO.
_{The 2} / Si interface may be heated instantaneously.

[0023]

As described above, according to the present invention, the POA process is performed by using the IR annealing furnace which is excellent in controllability at high temperature and for a short time, so that the SiO ₂ film can be formed without changing the underlying bond. Improved properties can be achieved.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between IR annealing treatment time and Nss in an example according to the present invention.

FIG. 2 is a diagram showing a relationship between POA processing time and Nss in a comparative example.

FIG. 3 is a diagram showing a withstand voltage distribution of an IR-annealed sample in an example according to the present invention.

FIG. 4 is a diagram showing a breakdown voltage distribution of a comparative example.

[Explanation of symbols]

I: Sample subjected to IR annealing at 1100 ° C. II: Sample subjected to IR annealing at 1150 ° C. III: Sample subjected to IR annealing at 1000 ° C. IV: Sample subjected to POA treatment in wet O ₂ V: Dry O Sample subjected to POA treatment in ₂ (a) ...... Concentrated film destruction part of sample according to the present invention (b) …… Concentrated film destruction part of comparative sample

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Kazuhiro Tajima 6-735 Kitashinagawa, Shinagawa-ku, Tokyo Sony Corporation

Claims (5)

[Claims] 1. A step of forming an insulating film on a semiconductor substrate,
A method of manufacturing a semiconductor device, comprising: a step of heating the semiconductor substrate and the insulating film by an IR heating method; and a step of forming an electrode on the insulating film. 2. The method of manufacturing a semiconductor device according to claim 1, wherein the insulating film is formed by oxidizing the surface of the semiconductor substrate with an oxidizing gas. 3. The method for manufacturing a semiconductor device according to claim 1, wherein the step of heating the semiconductor substrate and the insulating film by the IR heating method is performed in an atmosphere containing at least one of nitrogen, oxygen and an inert gas. A method of manufacturing a semiconductor device, comprising: 4. A step of forming an insulating film on a semiconductor substrate,
A method of manufacturing a semiconductor device, comprising a step of heating the semiconductor substrate and the insulating film by an IR heating method in an atmosphere containing at least one of nitrogen, oxygen and an inert gas. 5. A method of manufacturing a semiconductor device, comprising the steps of forming an insulating film on a semiconductor substrate in an atmosphere containing chlorine element, and heating the semiconductor substrate and the insulating film by an IR heating method.