JPS6229131A - Thin film formation - Google Patents

Abstract

PURPOSE:To accelerate the filming speed while arresting ultrafine particles produced by photoexciting reaction effectively on the substrate by a method wherein both reaction gas feeding and substrate temperature are controlled synchronizing with laser beam irradiation. CONSTITUTION:A substrate 12 is loaded upon a stage 11 in a reaction chamber 28 while the temperature of stage 11 is controlled by an infrared ray lamp 40 and a coolant feeder 46. In order to accelerate the filming speed on the substrate 12, the substrate temperature is lowered synchronizing with laser beam irradiation. Then in order to increase the filming capacity on the substrate 12 as the next process, the substrate temperature is raised stepwise. Next reaction gas is fed from a nozzle 26 connected to a cylinder through the intermediary of flow rate controllers 20. In case of pulse laser beams, oscillating pulse signals are transmitted to the other controller 48 to control both temperature of substrate 12 and feeding of reaction gas synchronizing with the pulse signals. On the other hand, in case of continuously oscillating laser beams, a mechanism such as a chopper to transfer laser beams to pulses is provided to transmit the synchronized signals to the controller 48.

Description

[Detailed description of the invention] [Field of application of the invention] The present invention relates to selective chemical processing equipment, and more particularly.

This invention relates to a technique that uses energy beams to selectively cause chemical vapor deposition reactions.

[Background of the invention]

It has been known that when a laser beam is irradiated onto the surface of a substrate that is in contact with an organometallic compound, a thin metal film is formed on the surface of the substrate due to a photochemical reaction. For example, Applied Physics Letter 35 (2) 175
(1979) (Appl, Phys, Lett.

35(2), 175 (1979)) Furthermore, when a laser beam is irradiated while an organometallic compound and a gas such as NO2 or N20 are in contact with the substrate surface, the substrate coating 42
(8) 662 (1983) (Appl, Ph
YS, Lett, 42(8).

The prior art disclosed in Japanese Unexamined Patent Publication No. 58-165330 will be described with reference to FIG.

In FIG. 3, a semiconductor substrate 12 placed on a stage 11 in a reaction chamber 7 comes into contact with a gas introduced from a gas inlet 9. As shown in FIG.

The laser light emitted from the laser light source 1 passes through the dye 2, passes through the mirror 6 driven by the position control system 5, passes through the entire entrance window 8 of the reaction chamber 7, and is irradiated onto the semiconductor substrate 12.
A thin film is formed on the semiconductor substrate 12.

Conventionally, in order to form a metal thin film on a semiconductor substrate, the thin film to be formed is first deposited on the entire surface of the substrate, and then a photolithography technique is used.

The common method was to remove the unnecessary parts, but as an alternative method, this technology utilizes a photochemical reaction.
Patterning directly onto the substrate.

This technology improves the precision of thin film formation on the substrate,
Improving the rate of thin film formation is an important issue. In order to improve the thin film formation rate, it is important to increase the energy density per unit area of laser light or the like irradiated onto the substrate surface. However, when the intensity of the laser beam is increased, precipitates generated by photochemical reactions adhere not only to the semiconductor substrate surface 12 but also to the inside of the entrance window 8 of the reaction chamber 7, resulting in a decrease in the amount of laser beam transmission. , there is a problem that the precipitation rate does not increase.

In the figure, 3 is a diffraction grating, 4 is a laser beam, 10 is a gas inlet,
13 is a heating coil, 14.15 is an electrode.

16.18 is a laser.

[Purpose of the invention]

An object of the present invention is to provide a selective processing apparatus that does not require consideration of contamination of the entrance window of the reaction chamber and that can form a thin film at a high speed.

[Summary of the invention]

A reaction that uses light energy to cause a chemical vapor deposition reaction is called photoCVD (Chemical Vapor
, [) epos i tion).
Conventionally, mercury lamps, xenon lamps, and the like have been widely used as light sources. In recent years, the development of various lasers has progressed,
This has come to be widely used as a light source for optical CVD. The reaction gas for photo-CVD includes, for example, a silane gas such as 5i)(4゜81zHe) to form a Si film, and G to form a Ge[' film.
e Germanic gas such as H4 can be used. Furthermore, in order to form a high melting point metal film, for example, Cr (
CO)s, Mo(CO)a.

Carbonyl compounds such as W(Co)a and Cot(Co)s can be used. Additionally, organometallic compounds such as At(CH3)s, Zn(CHs)
By using z, Cd(CH3)z, etc.
Thin films of metals At and Zfllcd can be formed. In addition, by using a mixed gas of an organometallic compound and a gas that can be an oxygen source, such as N z O,
A thin film of 40s, ZnO, etc. can be formed. S
A *5fsN4 thin film can also be formed from a mixed gas of iH4 and NHs. Furthermore, by mixing a gas containing an element of group 1 of the periodic table and a gas containing an element of group V, it is also possible to form a thin film of, for example, Galys.

When such a reactive gas is irradiated with an energy beam such as a laser, the reactive gas is photoexcited and active molecules are generated, which collide with each other to generate micronuclei, which are then After adhering to the substrate, these micronuclei are thought to gather through migration to form a thin film.

The inventors conducted detailed experimental studies on this thin film formation process, and as a result, completed the present invention.

When a reactive gas is irradiated with a laser beam, microparticles are formed along the laser beam, and when the substrate is at room temperature,
They slowly move along with the gas flow in the reactor,
A part of it adheres to the substrate surface, and most of it moves to the exhaust system and does not participate in film formation.

In addition, a portion of it adheres to the reactor wall and does not participate in film formation on the substrate. In order to form a thin film from fine particles attached to a substrate, microcrasion on the substrate is the rate-determining process, so the film formation rate is extremely slow when the substrate is at room temperature. Therefore, the substrate is usually heated to increase the migration rate on the substrate. However, when the substrate is constantly heated, due to gas convection within the reactor, the microparticles generated by the laser beam rise along with the gas flow, reducing the number of particles that adhere to the substrate. However, the film formation rate does not increase.

Furthermore, if the temperature of the reactor wall is lower than the substrate temperature, most of the generated fine particles will adhere to the inner wall of the reactor and will hardly participate in film formation on the substrate.

As a result of experimentally examining the behavior of hemoglobin and the film formation rate in a reactor as described above, the present inventors controlled the supply of reactant gas and the substrate temperature in synchronization with laser beam irradiation. By doing so, it is possible to effectively form a film on the substrate.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail based on examples.

An embodiment of the present invention is shown in FIG. 1, and a sequence for controlling the reaction gas and substrate temperature in synchronization with laser beam irradiation is shown in FIG.

A substrate 12 is supported on a stage 11 within the reaction chamber 28 . A substrate such as a silicon wafer can be used. The temperature of the stage 11 is controlled by an infrared lamp 40 and a coolant supply device 46.

The temperature of the substrate is measured by a temperature detector 50 and controlled by these two devices. In this example.

Infrared lamps are used as substrate heating devices, but
Other devices having a function of heating the substrate, such as a heater built into the stage 11, carbon dioxide laser irradiation, or the like may also be used.

Further, as the substrate cooling device, for example, a device having a function of cooling the substrate, such as cold methanol or liquid nitrogen circulation, can be used.

The flow rate control device 20 enters the reaction chamber 28 from the cylinder.
A reaction gas is supplied from the nozzle 26 through the nozzle 26 . In addition, as one reaction gas, not only substances that are gaseous at room temperature but also liquid organometallic compounds can be used. In this case, gas such as hydrogen or helium is bubbled in the cylinder 22 whose temperature is controlled by a constant temperature bath 24. can be supplied. A plurality of these reaction vessels can be installed, and a plurality of organometallic compounds can be supplied into the reaction chamber 28. Reaction chamber 2
What is the shape of the nozzle 26 that supplies gas into the interior of the 8?

It is preferable that the gas flow on the substrate 12 be close to a laminar flow, and any shape can be used.

The interior of the reaction chamber 28 is evacuated by a high vacuum exhaust system 42 before starting the reaction. After the reaction starts.

Through the exhaust nozzle 30i, any reaction pressure 1 e.g.

The pressure is controlled to be maintained at 0.1 to 10 Torr and exhausted by an exhaust system 44. The exhaust system 44 may be shared with the high vacuum exhaust system 42 and may use a butterfly valve or the like.

The laser beam oscillated from the laser light source 1 is shaped into an arbitrary beam shape via the lens system 3B and sent to the reaction chamber 2.
The inside of the reaction chamber 28 is irradiated through the window plate 32 of 8. As the laser, an excimer laser can be used, but other lasers, such as solid-state lasers, can be used.

A gas laser, a dye laser in combination with these lasers, etc. can be used, and light matching the absorption wavelength of the reaction gas to be deposited on the substrate can be used. In the case of a pulsed laser, an oscillation pulse signal is sent to the control device 48, and the temperature control of the substrate 12 and the introduction of the reaction gas can be controlled in synchronization with the oscillation pulse signal. In the case of a continuous wave laser other than a pulsed laser, a mechanism such as a chopper that pulses the laser light can be provided and a synchronization signal can be sent to the control device 48.

Also, other energy beams other than lasers, e.g.

Mercury lamp, xenon lamp, SOR (3ynchr
otoron Qrbita 11 (adiation
, synchrotron radiation), etc., similar effects can be obtained. Further, the direction in which the substrate 12 is irradiated with laser light or the like may be parallel to or perpendicular to the substrate 12. Furthermore, the same effect can be obtained even if these two methods are combined.

The reaction chamber 28 has a window plate 32 through which the laser beam enters.

By introducing a purge gas such as helium from the purge nozzle 34, it is possible to completely prevent deposits from adhering to the window plate 32. Further, fluororesin oil or the like may be applied to the inside of the window plate 32. 24 is a constant temperature bath.

In this apparatus having such a configuration, the control device 48 causes the introduction of the reaction gas and the temperature side of the substrate to be performed in synchronization with the t-noser irradiation into the reaction chamber 28. This sequence is shown in FIG. A reaction gas is supplied into the reaction chamber 28 via the flow rate control device [20] a time Δ before the laser irradiation time. The supply time of the reaction gas is as follows:
This is the period until the reaction gas reaches the top of 2, and the laser beam is irradiated accordingly. Laser beam is 25mX
It is a 2 mm rectangle and is adjusted to a height of 5 days above the board. The effect is the same even if the shape of this laser beam is made into any shape by the lens system. Furthermore, the distance between the substrate and the laser beam can also be changed arbitrarily. When a laser beam is irradiated into a space where a reactive gas exists, the reactive gas is excited by the laser light and a photodecomposition reaction starts. When an organometallic compound such as trimethylaluminum is used as a reaction gas, the following reaction occurs.

v At(CHs)s□ At+ product At atoms generated in this reaction are caused by collisions.

All of the ultrafine particles are generated and float along the optical path of the laser beam, and if no manipulation is applied, they float and move along with the gas flow within the reaction chamber 28.

In the present invention, in order to move the ultrafine particles generated above onto the substrate 12 in a short time and improve the film formation rate on the substrate 12, the substrate temperature is lowered in synchronization with laser beam irradiation. With this operation.

The ultrafine particles generated above smoothly move and adhere to the substrate 12. After the fine particles have been deposited, the next step is to increase the substrate temperature to a desired temperature in order to increase the film formation on the substrate 12. This temperature control of the substrate 12 is achieved by controlling the supply of refrigerant and the infrared lamps by the control device 42. By this operation, the ultrafine particles generated by the V-the beam can be forcibly moved and attached onto the substrate 12, and a film can be efficiently formed on the substrate 12.

Furthermore, by repeating this operation in synchronization with the laser beam, a film can be formed on the substrate 12.

A case is shown in which trimethylaluminum (denoted as TMA) is used as a reaction gas. TMA is a liquid at room temperature and is supplied to the reaction chamber 28 using Ht gas as a carrier.

An excimer laser is used as the laser, and ArF (19
A laser beam of 3 nm) was used. In this case, the energy per pulse is approximately 200 mJ. This V-za light is transmitted through a lens system using a cylindrical lens.

It was made into a rectangle of 25 m x 3 m and 5W of light was irradiated onto the substrate 12. 0.5 seconds before laser beam irradiation, TMA was supplied to the substrate 12 at 5 Torr using the flow rate control device 20. Simultaneously with the V-the beam irradiation, the substrate 12 was cooled to i-100C by the coolant supply system 46, and then the substrate 12 was heated by the infrared lamp 40 to bring the substrate temperature to 200C for 5 seconds. By repeating this operation, it was possible to completely form an At thin film on the substrate at a rate of 2000/-. Without performing this operation, the substrate temperature is 20
When 0C was kept constant and the reaction gas was also continuously flowed, the film formation rate was about 1000 people/-. The film quality was almost the same in both methods.

Another advantage of the present invention is that since the ultrafine particles generated on the V-za beam in the reaction chamber 28 are efficiently collected on the substrate, the amount of by-products deposited inside the laser entrance window is extremely large. This means that it can be reduced to When precipitates are formed inside the laser entrance window, the incident power of the V-laser light is extremely reduced.

Since the efficiency of film formation is greatly reduced, it is a great advantage to be able to prevent this.

This is shown in other embodiments of the present invention. A plurality of gases can be used as the reaction gas, and TMA as an organometallic compound.
t and nitrous oxide (1'hO) was used.

TMA was supplied to the reaction chamber 28 using helium as a carrier.

In order to cause a photochemical reaction using a laser.

It is well known that there must be light absorption of the reactant gas. Spectra of TMA and NzO in the ultraviolet region @
Shown in Figure 4. In order to cause a photochemical reaction with an excimer maser, t(r F (248 nm) or ArF (193 nm) laser f light must be used.
There is no absorption for these gases.

However, since the V-J' light of KrF (248 nm) has a small absorption with respect to the reaction gas, even if the same gas t1fr: is supplied, the reaction rate is lower than when the entire V-J' light of ArF (193 nm) is irradiated. is slow.

It is known that TMA and Ni0 react according to the following formula.

TMA 10Nz O-+ktz O1+f4E, acid This reaction is complex and the elementary reactions are not precisely understood, but the precipitate is alumina and other gaseous substances are produced as by-products.

For the mixed gas of TMA and NiO, it is necessary to add more than twice as much N20 as TMA, and the total pressure in one reaction chamber 28 is 5'porr! Ic was supplied.

ArF (193nm)'t= was used as the V-zer, and the lens system was used to make it 25m x 3m+ wide on the substrate.
The fl position was irradiated. The energy per laser pulse was 200 m, T. The temperature of the substrate is -100
It was controlled in synchronization with laser beam irradiation between tll' and 35CI'. In this case, a thin film of alumina was formed on the substrate. Silicon was used as the substrate, and it became clear that this alumina had sufficient performance as an insulating film.

On the other hand, when the substrate temperature was controlled between -100C and 100C, an ultrafine particle layer of alumina was formed on the substrate.
A porous fine particle layer of alumina with a diameter of 0 was formed.

In this case, this porous alumina layer serves as a carrier for the catalyst, for example.

It can be used as a fuel chamber reservoir N mark.

As a first step, nickel carbonyl (Ni(COL)) was supplied to the thus formed alumina support layer along with a hydrogen carrier according to the operation of the present invention.
o) a is photolyzed by V-za to produce ultrafine Ni particles, which adhere to the alumina carrier layer. The Ni-supported alumina layer can be used as a catalyst for steam reforming, for example as a 'B' layer for internal reforming molten carbonate fuel cells. In this case, methane and steam can be introduced directly into the fuel cell.

Although the present invention has been described above with reference to examples, it is clear that many other modifications are possible. In particular, in addition to the organometallic compounds mentioned above, dimethyl chloride 2. By using dimethylzinc, a metal film of (::d, Zn) can be formed, and by using a carbonyl compound such as Cr, Mo, W, etc., a silane-based compound 1 that can form a metal thin film thereof, for example. , S I H4+
81z) (s and ammonia, Cz H2'!!: By using it, a 5fsN4.SiC film can be formed.

Further, by using a mixed gas containing elements of Groups 1 and V of the periodic table, a compound semiconductor of Group 1-V can also be formed.

In any case, it is within the scope of the present invention to form a thin film while controlling the substrate temperature and supply gas in synchronization with light as an excitation energy source.

The idea of the present invention is also effective when a reactive gas is decomposed to form a thin film using an electron beam plasma or the like in addition to a light beam such as a laser or a mercury lamp as an energy beam. In this case, it is also possible to combine a plurality of energy beams.

The idea of the present invention is also effective when a functional film is formed by laminating a plurality of different thin films.

That is, by controlling the temperature of the substrate, the reaction gas A' is adsorbed onto the substrate, and then the adsorption surface is irradiated with an energy beam to form a film.

Thereafter, the reaction gas B can be similarly adsorbed to stack the films. By repeating this operation, a new functional film can be formed.

In order to improve the throughput of a substrate on which a thin film is formed, it is necessary to make one reaction continuous. In this case, it is necessary to provide a front chamber and a rear chamber in the reaction chamber, and to provide a device that allows the substrate to be taken in and out under vacuum.

The ultrafine particle nuclei generated by decomposing the reaction gas using an energy beam are placed on a substrate provided in a chamber separate from the reaction chamber.
Collect it by controlling the temperature of the substrate.

Forming a film therein is also included in the idea of the present invention.

The energy beam used here may be an optical beam such as a laser, a mercury lamp, or an electron beam or a plasma.

〔Effect of the invention〕

According to the present invention, ultrafine particles generated by a photoexcitation reaction can be efficiently collected on a substrate, and the film formation rate can be improved.

[Brief Description of the Drawings] Fig. 1 is a schematic diagram of an embodiment of the present invention, Fig. 2 is a control sequence diagram of the present invention, Fig. 3 is a conventional schematic diagram, and Fig. 4 is an ultraviolet spectrum of a reaction gas. Show the diagram. DESCRIPTION OF SYMBOLS 1... Laser, 11... Stage, 12... Semiconductor substrate, 20... Flow rate control device, 22...
Cylinder, 24... Constant temperature chamber, 26... Nozzle, 28
...Reaction chamber. 30...Exhaust nozzle/l/, 32...Window plate, 34...
・Purge nozzle, 38...Lens system, 40...
・Infrared lamp, 42... High vacuum exhaust system, 44
...exhaust system, 46...refrigerant circulation system, 4
8...Control device.

Claims (1)

[Claims] 1. A method for selectively forming a thin film by irradiating an energy beam output from an energy source onto a substrate that is in contact with a reactive gas, comprising the steps of: A thin film forming method characterized by supplying source gas in synchronization with an energy beam and controlling substrate temperature. 2. A method for forming a thin film according to claim 1, characterized in that the energy beam is a laser beam selected to have an excitation wavelength that is highly absorbed by the reaction gas. 3. A method for forming a thin film according to claim 1, characterized in that a gas containing an organometallic compound containing an element corresponding to the thin film to be formed is used as the reaction gas. 4. The thin film forming method according to claim 1, wherein the thin film to be formed is a metal, a semiconductor, or an insulating film. 5. A thin film forming method according to claim 1, characterized in that a light source that intermittently irradiates a pulsed laser, a mercury lamp, a xenon lamp, or a continuous wave laser is used as the energy beam. 6. The method for forming a thin film according to claim 1, wherein the thin film to be formed is made of a layer of fine particles of ceramics.