JPH0770535B2 - Method for manufacturing semiconductor device - Google Patents

Description

The present invention relates to a method for manufacturing a semiconductor device. INDUSTRIAL APPLICABILITY The present invention can be applied to, for example, manufacturing of a memory device, and in that case, the characteristics of a thin SiO ₂ film which is required particularly in a recent MOS memory (DRAM, SRAM, etc.) can be remarkably improved.

SUMMARY OF THE INVENTION The present invention is a method for manufacturing a semiconductor device, wherein a semiconductor substrate is treated in an oxidizing atmosphere to react a semiconductor material with an oxidizing component in the atmosphere to form an oxide film on the semiconductor substrate, After that, by performing a heat treatment by an IR heating method, the unbonded species between the semiconductor substrate material and the oxide film can be reduced, and the interface characteristics can be improved, whereby the film characteristics can be significantly improved by heating for a short time. It was done like this.

[Conventional technology]

Recent semiconductor devices, such as MOS memories, have been miniaturized, and gate oxide films and the like have become extremely thin according to scaling rules.

For example, the capacity oxide film thickness in 256K DRAM is 100-120Å,
For 1Mbit DRAM, a thin film of about 80-100Å is desired. The same applies to the oxide film in SRAM cells: 256K SRAM with 200Å, 1MbitSR
AM requires less than 150Å.

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, a thin SiO ₂ film is usually formed by an oxidation furnace at about 900 ° C. or a low pressure oxidation method using an oxygen / nitrogen mixed gas (O ₂ + N ₂ ) carrier with a low effective oxygen partial pressure. The oxidation method has a problem in the denseness of the oxide film, and there is a concern that the breakdown voltage may decrease and the interface state may increase.

[Problems to be solved by the invention]

As described above, a low-temperature low-pressure oxidation method or the like has been studied to form a thinner SiO ₂ film than before, but the film obtained by this method has no SiO _x bond or unbonded at the SiO ₂ / Si interface. It is said that there are Si atoms, and these can cause an increase in the interface state and a deterioration in breakdown voltage.

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 the SiO ₂ film by using an IR annealing furnace which has excellent controllability at high temperature for a short time in order to solve the above problems.

[Means for solving problems]

The above-mentioned purpose is a step of reacting a semiconductor material with an oxidizing component in the atmosphere by treating the semiconductor substrate in an oxidizing atmosphere to form an oxide film on the semiconductor substrate, and then performing heat treatment by an IR heating method. By reducing unbonded species between the semiconductor substrate material and the oxide film, and improving the interface characteristics, by a method for manufacturing a semiconductor device,
To be achieved. IR heating should be short. The IR heating referred to in the present invention includes not only heating by halogen lamp light or the like, but also heating of the sample by laser light directly irradiated on the sample.

The structure of the present invention is specifically described as follows. That is, for example, a semiconductor wafer on which an oxide film has been grown by a normal oxidation method can be uniformly irradiated with high-output halogen lamp light or the like, and heated instantaneously.

[Action]

In the present invention, for example, by performing IR heating at a high temperature after the growth of the SiO ₂ film, the unbonded Si—O bond at the SiO ₂ —Si interface can be made into a sufficient SiO ₂ bond, thereby improving the interface characteristics. The obtained semiconductor device 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.

〔Example〕

Examples of the present invention will be described in detail below. Needless to say, the present invention is not limited to the examples described below.

Example 1 In this example, CZ (100) nty was used as an experimental sample.
pe2 ~ 3ohm-cm is used, and this is 1100 ℃, O ₂ + HCl (1%)
A gate oxide film (SiO ₂ ) was grown to 900 Å in the atmosphere. Next, as a POA (Post-Oxidation-Anneal) treatment of the SiO ₂ film, an IR annealing (here, halogen lamp heating) treatment was performed at 1000 to 1150 ° C. for 1 second to 2 minutes in an N ₂ atmosphere.
After that, Al vapor deposition and metal sintering (400 ° C., 60 minutes) were performed to create a MOS capacitor.

In Fig. 1, the IR annealing temperature is 1000 ° C (indicated by line III in the figure), 1100 ° C (indicated by line I), and 1150 ° C, respectively.
Treatment time and surface charge Nss (cm)
^-2 ex ^v-1 ).

As is clear from FIG. 1, 1100 shown in lines I and II
The Nss value of the sample according to the present invention which has been subjected to the IR annealing treatment of 1 ° C. and 1150 ° C. is the same as that of the 1000 ° C.-treated sample shown by line III
It can be seen that it has lower interfacial properties than the Nss value. Further, the Nss value of the sample according to the present invention which has been subjected to the IR annealing treatment at 1100 ° C. or higher is instantaneously 0.6 to 1 × 10 ⁹ cm ⁻² e
It is v ⁻¹ , which is 1/5 to 1/10 of that of the sample without POA treatment (Nss = 5.9 × 10 ⁹ cm ⁻² ev ⁻¹ ) indicated by the treatment time of 0.

FIG. 2 shows the POA treatment of the SiO ₂ film grown in the same manner as described above for wet O ₂ (indicated by line VI in the figure) and dry O 2
₂ is a comparative example performed in an electric furnace at 1000 ° C. in the atmosphere of ₂ (shown by the line V), but to obtain Nss of 1 × 10 ⁹ cm ^-2 ev ^-1
It takes more than 60 minutes, and under this condition, the junctions already formed during the gate oxide film growth such as the three-dimensional element junction, the well layer in the fine MOS, the channel stop region, etc. are largely redistributed. On the other hand, the samples according to the present invention shown by lines I and II in FIG. 1 instantaneously have an Nss value of 1 × 10 ⁻⁹ cm ⁻² ev ⁻¹ or less, and the sample according to the present invention by a short time IR annealing treatment. It is clear that the film characteristics are remarkably improved by the method.

Example 2 Using the same CZ (100) ntype 2 to 3 ohm-cm Si substrate as in Example 1, a thin SiO ₂ film of about 150 Å was formed. FIG. 3 shows the breakdown voltage distribution when POA treatment was performed by IR annealing at 1100 ° C. for 10 seconds in N ₂ atmosphere. As a comparative example, FIG. 4 shows the breakdown voltage distribution of a similar SiO ₂ film steam-treated at 900 ° C. In both FIG. 3 and FIG. 4, the horizontal axis represents the electric field applied for film breakdown, 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 the figure of the comparative sample shown in FIG. Compared to the 8.5-9.5 MV / cm shown in the middle (b), it can be seen that it is moving to the high electric field side. Further, the IR annealing treatment according to the present invention is more concentrated in the breakdown voltage distribution,
It can be seen that the in-plane uniformity of the wafer is improved.

The atmosphere of the IR annealing treatment is in N ₂ as well as in O ₂ .
It can be performed in N ₂ + O _{2 or} Ar. In addition, IR heating uses high-output halogen lamp light and CO of 9-10 μm wavelength.
_{2 The} SiO ₂ / Si interface may be momentarily heated by being matched with the intrinsic absorption peak of Si—O by laser light irradiation.

〔The invention's effect〕

As described above, according to the present invention, the POA treatment is performed using an IR annealing furnace that has excellent controllability at high temperature and for a short time, so that the characteristics of the SiO ₂ film can be improved without changing the underlying bond. To be

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the IR annealing treatment time and Nss in the example according to the present invention. Fig. 2 shows P of the comparative example
It is a figure which shows the relationship between OA processing time and Nss. FIG. 3 is a diagram showing the withstand voltage distribution of the IR annealing sample in the example according to the present invention, and FIG. 4 is a diagram showing the withstand voltage distribution of the comparative example. I …… Samples IR-annealed at 1100 ℃ II …… Samples IR-annealed at 1150 ℃ III …… Samples IR-annealed at 1000 ℃ IV …… Samples POA-treated in wet O ₂ V …… Dry O Sample subjected to PAO treatment in ₂ (a) …… Concentrated film destruction part of the sample according to the present invention (b) …… Concentrated film destruction part of comparative sample

Front page continuation (72) Inventor Kazuhiro Tajima 6-735 Kitashinagawa, Shinagawa-ku, Tokyo Sony Corporation (56) Reference JP-A-60-12737 (JP, A)

Claims (1)

[Claims] 1. A step of forming a oxide film on a semiconductor substrate by reacting a semiconductor material with an oxidizing component in the atmosphere by treating the semiconductor substrate in an oxidizing atmosphere, and then performing heat treatment by an IR heating method. This reduces unbonded species between the semiconductor substrate material and the oxide film,
And a step of improving interface characteristics.