JPS6118122A - Semiconductor manufacturing apparatus - Google Patents

Abstract

PURPOSE:To reduce impurity mixing into a film, and to provide a high quality thin film, by introducing another substance reacting with the imprity when forming the film under a reduced pressure condition. CONSTITUTION:When an Si thin film is formed with an optical CVD method using a raw material gas of Si2H6, hydrogen is introduced into the vacuum vessel 5 from a hydrogen gas system 11, and active hydrogen is then produced by irradiating the interior of the vacuum vessel 5, using a light source 3 of a hydrogen discharge lamp with such a wavelength that hydrogen molecules can absorb light to decompose into atoms. In this state, ArF excimer laser light from an optical source 1 which is shaped into wide planar light by an optical system 2, is introduced into the vicinity of the entire surface of a wafer, while Si2H6 gas is introduced from a raw material gas system 10. The Si2H6 gas absorbs the ArF excimer laser light and is decomposed, forming an Si thin film on the substrate 6. Since oxygen remaining in the vessel would couple with active hydrogen atoms and is exhaused out of the vessel 5 by means of a vacuum exhausting system 8, oxygen in the resulted film can be reduced to about 1/20.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a semiconductor manufacturing apparatus, and particularly to a semiconductor manufacturing apparatus suitable for manufacturing high quality semiconductor materials with few impurities for LSI.

[Background of the invention]

ArF (wavelength 193 nm) and KrF (249 nm)
JPPL, Phys, Lett, Dan 183 (198
2) (by, R, lf, Andreatta at a
), a polycrystalline Si thin film is placed in the region 1a#, and a Si
It is formed using H4 as a raw material gas. However, in optical CVD using a vacuum ultraviolet lamp, a large amount of oxygen was mixed into the film. The reason for this is that the film formation rate when using a vacuum ultraviolet lamp is slower than when using an excimer laser (about 1/1000), so the contamination of oxygen becomes noticeable (that is, photon absorption in the gas phase). The excitation S generated by
It is thought that the density of iH4 molecules becomes lower and the oxygen remaining in the vacuum container becomes non-negligible.

Therefore, when forming an optical CVDSi film by spreading A r F, K r F, or F2 laser light using an optical system and irradiating the entire surface (approximately 80 d) of a 4-inch wafer, the light intensity on the substrate is 1/ of the known examples of et al.
100, the film formation rate (that is, the excitation S
It is well known that the iH (molecular density) is reduced and oxygen is mixed into the film, which poses a major problem when applying photo-CVD to an LSI process.

[Object of the Invention] An object of the present invention is to solve the above-mentioned problems and provide a method for efficiently forming a film of a high-quality semiconductor material containing few impurities, and a semiconductor manufacturing apparatus for the method.

[Summary of the invention]

To achieve the above objective, a second substance is introduced which chemically reacts with the undesired first substance remaining in the vacuum vessel. The chemical reaction between the first substance and the second substance forms a volatile substance containing the first substance, and the undesired first substance is removed from the chemical reaction for forming the desired film. This makes it possible to suppress the incorporation of impurities into the formed film.

In addition, when the chemical reaction between the first substance and the second substance does not occur as it is, or when the chemical reaction progresses slowly,
Provides the energy necessary for the reaction.

Now let us assume that the second substance is hydrogen. When hydrogen is exposed to ultraviolet rays or discharged, it becomes active hydrogen that easily reacts chemically with other substances. This active hydrogen then combines with an undesired first substance, such as oxygen, to form its hydride. This hydride is removed from the vacuum vessel by an exhaust system. Similar effects can also be achieved on arsenic, phosphorus, halogen, antimony, tin, etc.

Suitable light sources for producing active hydrogen include hydrogen discharge lamps, rare gas resonance lamps, and second harmonics of excimer lasers. Furthermore, Hg photosensitization using an Hg lamp can also be applied to the method of producing active hydrogen.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIG.

In this example, photo-CVD is performed using Si and HG as raw material gases.
A Si thin film is formed by the method.

The device used in this example is a vacuum container5. Raw material gas system 1
0. It is composed of a hydrogen gas system 11, a vacuum evacuation system 8, a light source 1 for raw material gas reaction, and a light source 3 for active hydrogen generation.

A 4-inch Si wafer was used as the substrate 6 after being cleaned using a conventional method. The inside of the vacuum container 5 is evacuated by the vacuum evacuation system 8.
After exhausting the air to Torr, the substrate 6 is heated to 20°C by the heater 7.
Heated to 0°C. Then, hydrogen was introduced into the vacuum container 5 from the hydrogen gas system 11 to a pressure of 10 Torr. Thereafter, active hydrogen was generated in the vacuum container 5 by irradiating the vacuum container 5 with the above light using a hydrogen discharge lamp with a wavelength at which hydrogen molecules absorb light and decompose into atoms as the light source 3. In this state, an A r F excimer laser beam as a light source 1 is shaped into a wide planar shape by an optical system 2 and introduced near the entire surface of the 4-inch wafer (see Fig. 2), and at the same time Si, H , was introduced up to 10 Torr (the total pressure inside the vacuum vessel 5 was 20 Torr). In this way, Si, H, absorbed the A r F excimer laser beam and decomposed, and a Si thin film was formed on the substrate 6 . The film formation rate at this time was about 0.1 μm/min.

When we measured the infrared absorption spectrum of this Si thin film, we found that the amount of oxygen in the film was 1/20 (approximately 0.Qlat, %
) decreased to a degree. This is because the oxygen remaining in the container combined with active hydrogen atoms, making it easier to be evacuated to the outside of the vacuum container 5 by the vacuum evacuation system 8.

In this example, in the photo-CVD of Si using an ArF excimer laser, introduction of hydrogen gas and irradiation with a hydrogen discharge lamp had the effect of reducing oxygen contamination into the Si film. This method can be applied to film formation under reduced pressure. Furthermore, the method for generating active hydrogen is not limited to light irradiation from a hydrogen discharge lamp, and a rare gas electrodeless discharge lamp, the second harmonic of an ArF excimer laser, etc. are also effective.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, when forming a film under reduced pressure, it is possible to reduce the amount of impurities mixed into the film. Therefore, a high quality thin film can be obtained, and the performance and reliability of the semiconductor device can be improved.

Also, the back pressure inside the vacuum container is 1O-”~1O-”Torr.
Therefore, the exhaust only needs to be exhausted for a short time, and the capacity of the exhaust system can be small. Therefore, mass productivity is improved and the entire device can be downsized.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an apparatus configuration according to an embodiment of the present invention, and FIG. 2 is a plan view showing how light from a light source 1 is shaped by an optical system 2 and guided to a substrate. 1...Light source for raw material gas reaction, 2...Optical system, 3...
・Light source for active hydrogen generation, 4... Light incidence window, 5...
vacuum container. 6... Board, 7... Heater, 8... Vacuum exhaust system,
9... Light incidence window, 10... Source gas system, 11...
Hydrogen gas system.

Claims (1)

[Claims] 1. An apparatus comprising a vacuum container, a means for heating a substrate, a means for forming a desired film on the substrate in the vacuum container, and an exhaust means for maintaining the inside of the vacuum container in a reduced pressure state. , a second substance that chemically reacts with the undesired first substance remaining in the vacuum container to form a substance that is easily evacuated by the exhaust means.
1. A semiconductor manufacturing apparatus comprising: means for introducing a substance. 2. The semiconductor manufacturing apparatus according to claim 1, wherein the means for forming the film is a chemical reaction of a raw material gas introduced into the container. 3. The semiconductor manufacturing apparatus according to claim 1, further comprising means for promoting a chemical reaction between the first substance and the second substance. 4. Semiconductor manufacturing according to claim 3, wherein the first substance is oxygen, the second substance is hydrogen, and hydrogen discharge lamp light is used as a means for promoting the chemical reaction between the two. Device. 5. The method according to claim 3, wherein the first substance is oxygen and the second substance is hydrogen, and the means for promoting the chemical reaction between them is to utilize the photosensitizing effect of Hg. Semiconductor manufacturing equipment.