JPH0666278B2 - Film forming equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention provides an apparatus for forming a good quality film under the low temperature condition required in the next-generation VLSI manufacturing process.

<Prior art> In the future development of VLSI, there is a limit when considering the profitability and the reliability of the device only by extending the technology of reducing the device circuit size, which realizes the high integration of the present VLSI. The situation is expected to be reached. Such high integration of VLSIs in the future can be achieved by SOI technology that multi-layers circuits with insulating films as proposed in 3D LSIs, or by horizontally leveling on the circuit plane like conventional semiconductor devices. It is expected to be realized by forming the formed transistor in the vertical direction. Moreover, in order to realize the high functionality of LSI, MOS-on one substrate
Bi-CMOS technology that mixes FETs and bipolar transistors is also expected to spread.

<Problems to be Solved by the Invention> In order to cope with such a change in the element structure, the existing technology cannot cope. For example, when trying to integrate a circuit in a multi-layered structure on an LSI such as a three-dimensional LSI, it is necessary to perform a heat treatment at about 1000 degrees for impurity diffusion or insulating film formation when forming an upper layer element. Inevitably, a refractory metal with high resistance is used. However, in order to increase the degree of circuit integration, an aluminum alloy having a lower resistance is more advantageous as a wiring material. Further, in the Bi-CMOS technology, a single crystal growth must be performed to form a bipolar, so a high temperature heat treatment in the vicinity of 1000 degrees is also required. Further, there is a problem that a warp of a substrate, a disconnection of a wiring material, and the like occur due to a heat treatment cycle at high temperature, a defective product is likely to occur during manufacturing, and manufacturing conditions are severe.

At present, film formation of various materials for VLSI often requires a high temperature of 500 ° C. or higher. The reason is that thermal CVD, which uses a method of thermally decomposing the substrate temperature as a method of decomposing the raw material gas of the film, can form a high-quality film. For example, using plasma CVD, which is a low-temperature film-forming technology that has been developed in the past, it is possible to form semiconductor materials such as silicon, but it is a defect in forming minute transistors used in VLSIs. It has not been put to practical use due to its high density. Also, optical CVD that does not easily induce defects even at low temperature film formation
When the method is used, it is possible to form a film at a low temperature, but the film quality has a problem that the crystal grain size is small and the growth rate is small at a temperature of about 400 degrees. In addition, the source gas that can be decomposed by a laser or lamp in the ultraviolet region is limited unless the mercury sensitization method is used, and expensive equipment must be used. There is also a problem in the apparatus because the film deposition rate changes or dust is generated due to film deposition on the window into which light is incident.

Therefore, in recent years, various techniques have been vigorously studied in various fields for forming various materials required for VLSI at a low temperature of about 400 ° C.

The present invention has been made in view of the problems of the conventional film forming apparatus described above, and provides an apparatus for forming a film of a material such as a semiconductor, an insulator, or a metal necessary for manufacturing a VLSI under a low temperature condition. is there.

<Means for Solving Problems> The present invention is directed to a film forming apparatus for forming a thin film of a component contained in a raw material gas by simultaneously irradiating a substrate surface with an ultraviolet laser beam while decomposing the raw material gas by microwave discharge. In, the inner wall surface surrounding the region where the microwave is discharged is covered with an insulator, and has a translucent window provided on a side surface so that the ultraviolet laser light is irradiated to the substrate surface. A microwave introduction tube for introducing the microwave into the reaction chamber from above and in parallel to the reaction chamber and the substrate, and the ultraviolet laser light is obliquely applied to the surface of the substrate through the transparent window. And an optical system arranged at a position to provide a film forming apparatus.

<Operation> According to the present invention, on the substrate surface requiring film formation, the intensity of the laser beam irradiated on the substrate surface is adjusted in advance, so that uniform film growth can be performed at low temperature over the entire film formation region. It is possible to form a stable film with few defects.

<Example> The present invention, when forming various material films of VLSI at 400 ° C or lower,
This is an apparatus for performing film formation by performing laser irradiation at the same time as decomposition of the raw material gas by discharge, and by combining the advantages of both plasma CVD and optical CVD in this way, it is possible to deposit a high-quality film at low temperatures. Further, the present invention is a film forming apparatus having a method of uniformly forming a film on a large-diameter substrate and also a method of reducing irradiation damage due to charged particles.

In FIG. 1, the reaction chamber 1 is provided with a tiltable holding table 3 for supporting a substrate 2 for film formation. Reaction chamber 1
A waveguide 4 is coupled to the wall surface of the substrate 2, a microwave of 2.45 GHz is introduced parallel to the surface of the substrate 2, and a magnetic field is generated by a magnet 10 in a direction perpendicular to the introduced microwave. Can be applied. Further, a translucent window 5 is provided in the reaction chamber 1, and the substrate 2 is irradiated with the excimer laser light 6 at a desired angle. After the excimer laser light 6 is projected by the laser generator 7, the excimer laser light 6 passes through a light intensity adjusting unit 8 including an attenuator (reflecting plate) and a lens for adjusting the light intensity, and a laser beam scanning mechanism 9 is further applied. When passing, the beam direction is controlled, and not only the incident angle to the substrate 2 but also the irradiation area is adjusted to scan the surface of the substrate 2 two-dimensionally. 11 and
12 supplies a raw material gas or a dilution gas to the reaction chamber 1,
It is a system for exhausting air. At least the inner wall surface of the discharge region 13 of the reaction chamber 1 to which the micro-waveguide 4 is coupled is covered with an insulator such as quartz.

First, the characteristics of a film forming apparatus that uses both plasma CVD and optical CVD will be described.

Since the film forming apparatus decomposes the raw material gas in the microwave discharge part, there is no restriction on the raw material gas which causes a problem in photo CVD. However, when gas decomposition by microwave discharge is used, it is necessary to suppress the diffusion of charged particles, especially electrons, generated in the discharge region to the substrate.
This is because the electrodeless discharge that is a pollution source can be easily realized by using the microwave as the excitation source of the plasma, but the electron, which has good followability to the vibration of the electric field strength generated by the electromagnetic wave, has a higher energy state than the ion. Therefore, various problems occur. That is, when the means for suppressing the electron diffusion to the substrate is not used together, electron damage to the substrate occurs and the mobility of electrons and ions has a large difference, so that the potential of the plasma rises and the ion deposition on the deposited film is increased. Implantation may induce defects. Therefore, in order to suppress the diffusion of electrons, a magnet 10 is installed in the reaction chamber 1 and a magnetic field is applied. By thus applying a magnetic field perpendicular to the direction of the electric field in which the electrons are accelerated, it is possible to make the motion of the electrons spiral and reduce the effective diffusion rate of the electrons.
Further, by covering the microwave discharge region of the reaction chamber 1 with an insulating film, diffusion of electrons from plasma can be further suppressed.

Further, the substrate 2 is laser-irradiated by irradiating the surface of the deposited film with the laser beam 6 so that only the outermost surface of the deposited film rises in temperature and diffuses to remove defects due to charged particles. By the effect of, the film quality can be improved to a level equivalent to that obtained by thermal CVD. In this case, when light in the ultraviolet region is used, generally only the surface absorbs light because the light absorption coefficient in the ultraviolet region of a solid is large,
The temperature rise of the entire substrate can be suppressed to within 100 degrees.

Further, since the film is formed by diffusing the reactive species from the discharge region, uniform film growth cannot be performed on the entire substrate unless the distance from the end of the discharge region facing the substrate is constant. Therefore, the laser light 6 needs to be obliquely incident on the surface of the substrate 2. In this embodiment, the holding table 3 is tilted at an angle of 19.5 degrees, so that the laser beam 6 is irradiated onto the substrate 2 at an angle of 70.5 degrees.

In addition, since the output of the laser is limited at present, the processing area is a few centimeters square when the laser light is fixed, and it is impossible to process a substrate with a radius of about 10 cm which will be used in the manufacture of future VLSI. Therefore, in the present embodiment, a scanning mechanism 9 is provided to two-dimensionally scan the laser beam 6 on the substrate surface 2 to cope with a large area process. Also, while film formation is progressing over the entire substrate, it is considered that the annealing effect by the laser becomes less effective as the film becomes thicker. Therefore, during film formation, the laser scans the entire surface as one cycle and repeats that cycle to cover the entire surface of the substrate. On the other hand, laser irradiation is sequentially performed to form a film.

In the above equipment, a KrF (248 nm) excimer laser is used as a laser, a pulse oscillation oscillator of 100 Hz is used as a microwave (2.45 GHz), and SiH ₄ gas and Ar gas are mixed as a raw material gas to obtain a glass substrate at a substrate temperature of 400 ° C. When a film was formed on No. 2, crystal growth was confirmed. FIG. 2 shows the result of X-ray diffraction of a silicon crystal thin film grown using the above film-forming apparatus. A diffraction pattern peak with a narrow half width was obtained, indicating that a crystal with a relatively large grain size grew. I understand. The growth rate of the conventional thermal CVD silicon film deposited at 650 ° C. was 10-20 nm / min, and the crystal grain size was about 20 nm in the (110) orientation and the half-value width of the X-ray diffraction peak. In the film-forming apparatus, the film-forming speed is 20-30 nm / min and the (111) -oriented crystal grain size is about 40 nm. In this example, the film-formation rate is faster and a film having a larger crystal grain size is grown. be able to.

FIG. 3 shows the relationship between the film deposition rate and the flow rate ratio of the diluent gas and the source gas SiH ₄ .

In order to cope with film formation on a substrate with a large aperture, the scanning mechanism 9 scans the laser beam two-dimensionally and irradiates the laser light uniformly over the entire substrate to form a film, regardless of the substrate area. A homogeneous thin film can be grown.

Although the above embodiment has been described with reference to the case where a silicon film is formed, other metal films or insulating films can be similarly formed.

<Effect> As described above, according to the present invention, since it is possible to suppress the diffusion of electrons generated in the discharge region when gas decomposition by microwave discharge is used, it is possible to cause the electron irradiation damage to the substrate and the deposition of ions. A thin film can be formed at a low temperature without causing defects due to implantation into the film,
Problems such as wafer warpage and wiring breakage due to high temperature processing can be solved, impurity diffusion due to high temperature processing is eliminated, and aluminum alloy can be used in VLSI design, significantly increasing the degree of freedom, It is possible to easily manufacture the integrated semiconductor device.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention, FIG. 2 is an X-ray diffraction diagram of a thin film to which the present invention is applied, and FIG. 3 shows a relationship between a source gas and a deposition film velocity according to the present invention. It is a figure. 1: reaction chamber, 2: substrate, 3: holding table, 4: waveguide, 6: laser beam, 7: light source, 8: intensity adjusting unit, 9: scanning mechanism, 10: magnet.

Claims (1)

[Claims] 1. A microwave is discharged in a film forming apparatus for forming a thin film of a component contained in a raw material gas by irradiating a substrate surface with an ultraviolet laser beam simultaneously with decomposition of the raw material gas by microwave discharge. An inner wall surface surrounding the region is covered with an insulator, and a reaction chamber having a translucent window provided on the side surface so that the ultraviolet laser light is irradiated to the substrate surface, and the substrate, A microwave introduction tube for introducing the microwave into the reaction chamber in parallel and from above, and an optical system arranged at a position for obliquely irradiating the substrate surface with the ultraviolet laser light through the transparent window. A film forming apparatus comprising: