JPH0294430A - Photo-assisted cvd apparatus - Google Patents

Abstract

PURPOSE:To control the formation speed of a film by using the same chamber by controlling the pressure of inert gas containing mercury vapor in a chamber accommodating a light source. CONSTITUTION:A substrate holder 3 mounting a substrate 2 composed of semiconductor substrates and a sample stand 4 are accommodated in a film formation chamber 1 of a photo-assisted CVD apparatus. The holder 3 is mounted on the sample stand 4 by a chuck 5. A heater 6 is installed in the inside of the sample stand 4. Further, in the film formation chamber 1, a heater 6 is arranged, material gas is introduced from a gas feeding part 7, and gas in the film formation chamber 1 is discharged by an exhaust pump 8. an accommodation chamber 14 accommodating a light source 13 constituted of a low pressure mercury lamp is installed in the lower part of the film formation chamber 1, and the light from the light source 13 is reflected by a reflection plate 15. Inert gas containing mercury vapor is introduced into the accommodation chamber 14 from a gas feeding part 30, and gas in the accommodation chamber 14 is discharged by the exhaust pump 12. The film formation chamber 1 and the accommodation chamber 14 are partitioned by a light introducing window of synthetic quartz plate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an improvement in a photo-CVD apparatus that deposits a film on a substrate using a photo-excited chemical reaction.

(Prior Art) With the recent progress in semiconductor integrated circuits, miniaturization and high integration of devices are required, and to achieve this, a photoexcitation process, which is a semiconductor process that is performed at low temperature and is free from ion damage, is attracting attention. Various photoexcitation processes are beginning to be incorporated into the elemental technologies of integrated circuit fabrication, such as semiconductor epitaxial growth, etching, and deposition of metal, insulating, and semiconductor films. The light source uses an excimer laser in the ultraviolet range with high photon energy or a low-pressure water button.

When using a low-pressure mercury lamp, a mercury sensitization method using Hg as a catalyst is well known.

The present invention focuses on film deposition among the above optical processes, that is, photoCVD.
Regarding D, this is particularly related to the device configuration.

The film deposition rate of a photoCVD device is determined by the light intensity on the substrate to be deposited, the concentration of the source gas in the atmosphere, and in the case of mercury sensitization method, the mercury concentration in the atmosphere, etc. By optimizing these parameters, In the mercury sensitization method, 100 people/
It is possible to obtain a film deposition rate higher than win, and the device structure is also a structure that maximizes the film deposition rate.

On the other hand, when forming a laminated structure film of thick and thin films, it is necessary to form a dense film by slow film deposition when forming the thin film, and if the deposition rate is too high, the time to form the thin film will be significantly shortened. The instability of the light source in the early stage of forming the upper film, which is difficult to control over time, or the instability of radicals in the reaction vessel have a large influence, and the controllability of the film thickness is significantly reduced.

Therefore, in order to improve the film thickness controllability during thin film formation, it is necessary to lower the deposition rate during thin film formation.

The film deposition rate in photoCVD depends on the light intensity on the surface of the substrate to be deposited, the temperature of the substrate to be deposited, the pressure of the raw material gas in the reaction vessel, and the mercury concentration in the reaction vessel in the case of the mercury sensitization method. . Among these, changing the temperature of the substrate to be deposited and the pressure of the source gas in the reaction vessel not only changes the film deposition rate but also the characteristics of the deposited film, such as electron mobility and dangling bond density in the case of hydrogenated amorphous silicon. Therefore, it is difficult to control the film deposition rate by changing these conditions. Furthermore, the light intensity on the surface of the substrate to be deposited, for example, when a low-pressure mercury lamp is used as a light source, the light intensity of the light source is fixed due to the characteristics of the light source itself, and cannot be changed by externally applied voltage, etc. Further, the distance from the light source to the substrate to be deposited is a quantity specific to the optical VCD apparatus, and making it variable would complicate the structure of the optical CVD apparatus and is not practical. Another method is to insert an optical filter between the light source and the substrate to be deposited. For example, in the case of a low-pressure mercury lamp light source, a light source of both wavelengths can be used without changing the light intensity ratio of 18501 nm and 254 nm, which have their emission peaks. It is difficult to obtain a filter that attenuates the intensity. Furthermore, the mercury concentration in the mercury in the reaction vessel is controlled by controlling the temperature of a mercury vapor generator installed in the middle of the raw material gas introduction piping and controlling the mercury vapor pressure. , controllability including responsiveness is poor.

(Problems to be Solved by the Invention) As described above, in the conventional photo-CVD apparatus, it is difficult to control only the film deposition rate in film deposition in the same reaction vessel, and therefore, it is difficult to control only the film deposition rate when depositing a film in the same reaction vessel. When forming a film, there are problems in that film thickness control during thin film formation deteriorates and the thin film becomes less dense.

The present invention has been made in consideration of the above circumstances, and its object is to provide a photo-CVD apparatus that can easily control the film deposition rate during film deposition in the same reaction vessel.

[Structure of the invention]

(Means for Solving the Problems) The gist of the present invention is to evacuate the light source housing space in which the light source of a photoCVD apparatus is housed, and at the same time introduce an inert gas containing mercury vapor into the light source housing guide. By controlling the pressure inside the storage chamber, we can control the mercury concentration in the light source housing chamber, and use the light absorption by this mercury vapor to control the light intensity on the surface of the substrate to be deposited, making it possible to control the film deposition rate. be.

That is, the present invention provides a means for evacuating a light source housing chamber in which a light source is housed, and an inert gas containing mercury vapor in the light source housing chamber, in a photo-CVD apparatus that deposits a film on a substrate using a photo-excited chemical reaction. It is equipped with means for introducing gas and means for controlling the pressure inside the light source housing chamber.

(Function) According to the present invention, by controlling the pressure of the inert gas containing mercury vapor in the light source housing chamber, the film deposition rate on the substrate can be controlled easily and with good controllability.

(Example) Hereinafter, details of the present invention will be explained with reference to illustrated embodiments.

FIG. 1 is a schematic configuration diagram schematically showing a photoexcited film forming apparatus according to a first embodiment of the present invention.

In the figure, reference numeral 1 denotes a film forming chamber, and a substrate holder 3 on which a substrate 2 made of, for example, a semiconductor substrate is placed, and a sample stage 4 are accommodated in the film forming chamber 1.
It is attached to the sample stage 4 by. A heater 6 is provided inside the sample stage 4 .

Further, raw material gas is introduced into the film forming chamber 1 from a gas supply section 7, and the gas in the film forming chamber 1 is exhausted by an exhaust pump 8.

On the other hand, in the lower part of the film forming chamber 1, there is a housing chamber 14 that houses a light source 13 made of, for example, a low-pressure mercury lamp, and a reflecting plate 15 that reflects light from the light source is provided inside.

Inert gas containing mercury vapor is introduced into the storage chamber 14 from the gas supply section 30, and the gas in the storage chamber 14 is pumped through the exhaust pump 1.
2, the air is exhausted.

The film forming chamber 1 and the storage chamber 14 are separated by a light introduction window made of, for example, a synthetic quartz plate.

Next, the operation of the apparatus configured as described above will be explained.

First, the substrate 2 is attached and the inside of the film forming chamber 1 is evacuated by the exhaust pump, and an inert gas containing mercury vapor is introduced into the storage chamber 14 from the gas supply section 30 at a flow rate of 10,100 ESCC, and the exhaust pump 12 is used to evacuate the inside of the film forming chamber 1. The inside of the containment room 14 is numbered (To
rr) to several tens of Torr. Next, 5il14 gas and C2H□ gas containing mercury were supplied as raw material gases from the supply system 7 into the film forming chamber 1 at a flow rate of 10100 (s).
cC, 10 (SCCM), pressure 0.1 (Torr), and heated to 250 (
Heat to ℃). Turn on the low pressure mercury lamp 12 and set the wavelength to 25.
A thin film as a first layer is formed by irradiating the surface of the substrate 2 with ultraviolet light of 4 (nm).

After the formation of the first layer is completed, a thick film of the second layer is formed. First, in order to remove the raw material gas used in forming the first layer from the film forming chamber 1, the inside of the film forming chamber 1 is evacuated to 5×10'' (Torr) or less using the exhaust pump 8. The inside of the storage chamber 14 is also pumped with a certain number of exhaust pumps 12 (mTorr) in order to remove the mercury vapor introduced during the formation of the first layer film.
) or below. After that, while introducing only inert gas into the storage chamber 14 from the gas supply section 30, the inside of the storage chamber 14 is pumped at several Torr to several tens of Torr using an exhaust pump.
pressure. Next, SiH4 gas containing mercury is supplied from the gas supply system 7 as a raw material gas into the film forming chamber 1 at a flow rate of 101.
00 (SCC pressure 0.5 (Torr)), and the substrate 2
is heated to 250 [° C.] using a heater 6 such as resistance heating. The low pressure mercury lamp 12 is turned on and the wavelength is 254 [nm].
The second I4 thick film is formed by irradiating the surface of the substrate 2 with ultraviolet light of 185 (nm).

The formation of the third and subsequent layers may be performed in the same manner.According to this embodiment, when forming the thin film as the first layer, 25411 [Q, 185
The ultraviolet light of nm wavelength is absorbed, and the intensity of the ultraviolet light on the substrate 2 is reduced. As a result, the film deposition rate is reduced and the controllability of the thickness of the thin film is improved. Further, when forming a thick film as the second layer, since mercury vapor is not present in the storage chamber 14, the intensity of ultraviolet light on the substrate 2 is high, the film deposition rate is high, and the throughput is not reduced.

FIG. 2 is a schematic configuration diagram schematically showing an optical CvD apparatus according to a second embodiment of the present invention. In the figure, parts equivalent to those in FIG. 1 are given the same symbols.

9 in the figure is a preliminary exhaust chamber for substrate transfer, and is a gate valve I.
It is connected to the film forming chamber 1 by O. A substrate transport mechanism 11 is provided in the preliminary exhaust chamber 9, and the interior of the preliminary exhaust chamber 9 is evacuated by an exhaust pump 12.

According to this embodiment, it is possible to attach and detach the substrate 2 without exposing the inside of the film forming chamber 1 to the atmosphere, so that oxygen, nitrogen, moisture, etc. in the atmosphere are adsorbed to the walls of the film forming chamber, etc. This solves the problem of contamination as impurities in the deposited film, and also solves the problem of prolonged exhaust time in the film forming chamber due to the influence of the adsorbed molecules. Also, containment room 1
This embodiment is similar to the first embodiment in that the film deposition rate can be controlled by controlling the amount of mercury vapor in the storage chamber 14 while monitoring the pressure in the storage chamber 14.

FIG. 3 is a schematic configuration diagram schematically showing an optical CVD apparatus according to a third embodiment of the present invention. In the figure, parts equivalent to those in FIG. 2 are given the same symbols.

In this embodiment, in addition to the transport mechanism 11 for the substrate holder 3 containing the substrate 2, a film forming chamber 1 and a storage chamber 1 are provided in the film forming section.
The light introduction window 16 that separates the 4 is also transportable by the window transport mechanism 21, and is chucked by the chuck 17.

The storage chamber 14 and the preliminary evacuation chambers 9 and 19 are always evacuated by the exhaust pump 12, and when the light introduction window 16 is not chucked, the storage chamber 14 and the film forming chamber 1 are evacuated by the exhaust pump 8 to form a 5×10 -' (Exhaust to less than 3 Torr.

During film formation, the accommodation gap 14 is evacuated together with the preliminary evacuation chambers 9 and 14 by the exhaust pump 12, and the film deposition rate is controlled by introducing an inert gas containing mercury vapor from the gas supply section 30. This is similar to the first and second embodiments.

According to this embodiment, in addition to obtaining the same effects as those of the first and second embodiments, the light introducing window 16 can be attached and detached without exposing the film forming chamber l to the atmosphere. When forming a film that absorbs ultraviolet light, such as an amorphous silicon film, the film is deposited on the substrate 2 and at the same time, the film is also deposited on the film forming chamber 1 side of the light introduction window 16, and the deposited film thickness increases. There is a problem in that as the amount increases, the light illuminance on the substrate 2 decreases and the film formation rate decreases. One method for solving this problem is to prevent film deposition on the light introduction window 16 by applying, for example, Fonpurin oil to the film forming chamber 1 side of the light introduction window 16. However, according to this method, the light introduction window 16 has to be removed and reapplied with fluoroplastic oil each time a film is formed. As a result, oxygen, nitrogen, moisture, etc. in the atmosphere may be adsorbed to the inner wall of the film forming chamber 1 and mixed into the deposited film as impurities, or the exhaustion of the film forming chamber may be prolonged due to the influence of the adsorbed molecules. There is a problem.

According to this embodiment, it is possible to attach and detach the light introduction window 16 without exposing the film forming chamber 1 to the atmosphere, so that the above-mentioned problem is solved.

Note that the present invention is not limited to the embodiments described above. The light source is not limited to a low-pressure hydrogen lamp, but may also be a deuterium lamp, excimer laser, or the like. Further, the heater is not limited to resistance heating, and may be a halogen lamp or the like. Furthermore, conditions such as pressure, gas flow rate, substrate temperature, and applied power during film formation, etching of deposited films, and etching of metal electrodes on the substrate depend on the required film thickness and film quality.

It may be determined as appropriate depending on the amount of etching, etc.

In addition, the raw material gas is not limited to monosilane (Si114), but also higher-order silane (for example, silane (siaus)).
rtrisilane (si211s)), methylsilane-based gas (e.g. dimethylsilane (S i H□(CI(2
), ) or germane gas (e.g. germane (Ga
H4)) may be used. As a mixed gas, diborane (B21
16), phosphine (PH2).

It may also contain acetylene (c2n2) and the like. Furthermore, the thickness of the film to be formed is not limited to a-5i, but also silicon oxide film, silicon nitride film, compound semiconductor (e.g. GaAs
, Zn5e, etc.). When forming silicon oxide films, silicon nitride films, etc., use nitrous oxide (N20).
, ammonia (NH3) etc. to monosilane (Si11.)
It may be used in combination with etc. Alternatively, direct excitation without mercury may be used.

〔Effect of the invention〕

According to the present invention, it is possible to control the film deposition rate using the same chamber in a photo-CVD apparatus, maintaining high throughput by high-speed film formation when forming thick films, and maintaining high throughput by forming thin films at low speed. It is possible to form a laminated structure film of thick films with good controllability of film thickness in a dense area.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram schematically showing an optical CD device according to a first embodiment of the present invention, and FIGS. 2 and 3 are schematic diagrams showing optical CVD devices according to other embodiments of the present invention. FIG. 1... Film formation chamber 2... Substrate 3... Substrate holder 4... Sample stage 5.17... Chuck 6... Heater 7... Raw material gas supply system
8,12...Exhaust pump 9.19...Preliminary exhaust chamber 10.20...Gate valve 11.21.
...Transport mechanism 13...Low pressure mercury lamp (light source) 14...Accommodation chamber 15...Reflector plate 1
6...Optical window 18.22...Rail 30...Gas supply system agent Patent attorney Noriyuki Ken Yudo Mitsuyuki Matsuyama Diagram

Claims (3)

[Claims] (1) In a photo-CVD apparatus that photo-excited and decomposes a source gas by irradiation with light and deposits a CVD film on a substrate to be processed, a means for introducing an inert gas containing mercury vapor into a housing chamber in which a light source is housed; 1. An optical CVD apparatus comprising means for evacuating a storage chamber. (2) The photo-CVD apparatus according to claim 1, further comprising means for attaching and detaching the substrate to be processed without exposing the film forming chamber to the atmosphere. (3) A claim characterized in that the film forming chamber is equipped with means for attaching, detaching, and transporting a light introduction window for introducing light from a light source into the film forming chamber without exposing the film forming chamber to the atmosphere. Item 2. Optical CVD apparatus according to item 2.