JP3311563B2 - Thin film formation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a device such as a semiconductor device or a photoelectric conversion device, and more particularly to a method for depositing a thin film such as a metal film on a substrate.

[0002]

2. Description of the Related Art As a method of forming a thin film by deposition, CV is used.
D (Chemical Vapor Deposition)
n) The method is known. In this method, a reaction gas is introduced into a reaction chamber to cause a chemical reaction, and a reaction product is deposited on a substrate to form a thin film. This CVD method is used not only for forming a SiO ₂ film or a polysilicon (p-Si) film, but also for forming a metal thin film. Conventionally, a method of forming a metal thin film using the CVD method includes a compound material gas such as a metal fluoride such as tungsten fluoride (WF ₆ ) or a metal carbonyl compound such as tungsten carbonyl (W (CO) ₆ ). Is introduced into the reaction chamber, and a reaction gas such as hydrogen (H ₂ ), which reacts with the compound material to form a thin film, is introduced into the reaction chamber, and is excited by excitation means such as ultraviolet light, laser light, plasma, or heat. A method of disassembling and depositing a metal thin film on a substrate is known (see Japanese Patent Application Laid-Open No. 2-225670).

[0003]

However, in such a CVD method, a film is formed from a material gas, that is, a gaseous phase, and the compound material density on a substrate is low because of the gaseous phase. There is a disadvantage that. In addition, when the substrate is irradiated with the laser light or the like, the compound material existing as a gas phase above the substrate reacts with the reaction gas to form metal atoms. Because it disperses to some extent when it falls and accumulates,
Since the metal film is formed so as to be wider than the spot position of the laser beam, there is a disadvantage that the transfer accuracy in the laser pattern is low.

[0004] In view of the above circumstances, an object of the present invention is to provide a thin film forming method capable of increasing a film forming speed and increasing transfer accuracy in a laser pattern.

[0005]

According to the present invention, there is provided a method of forming a thin film, comprising the steps of: adhering a compound material to a surface of a substrate ;
And a step of forming a thin film by reacting the hydrogen gas and the compound material with an energy beam.

In this method, a film is formed from the compound material attached to the substrate surface. Since the compound material is present in the attached state, the density of the compound material on the substrate is high. Can be faster. Ma
In addition, hydrogen gas is ionized into the compound material attached to the substrate surface.
Hydrogen gas in the compound material
Is present to enhance the film formation reaction. Furthermore, when the energy beam is directed toward the substrate, the compound material adhering to the substrate surface reacts with the reaction gas to form a thin-film product. , The dispersion of the film-forming product is suppressed. Therefore, a thin film is formed without spreading to the spot position of the energy beam, and the transfer accuracy in the beam pattern can be increased.

[0007] The thin-film forming method of the present invention includes the steps of depositing a compound material on the surface of the substrate adsorption or by condensing a compound material gas in the reaction chamber on the surface of the substrate by cooling the substrate, said compound material Water ionized in
And a step of forming a thin film by reacting the hydrogen gas and the compound material with an energy beam.

According to this method, when the compound material exists as a gas phase at room temperature, the compound material can be adhered to the surface of the substrate by adsorption or condensation. And the transfer accuracy in the beam pattern can be increased.

[0009]

Embodiment 1 Hereinafter, a reference example of an embodiment of the present invention will be described with reference to the drawings.

FIG. 1A is a cross-sectional view showing a schematic configuration of a thin film manufacturing apparatus, and FIG. 1B is an enlarged explanatory view of a portion indicated by an arrow A in FIG. In the chamber (reaction chamber) 1,
By a gas introduction path (not shown), for example, a tungsten fluoride (WF ₆ ) gas as a compound material gas and a hydrogen (H ₂ ) gas as a reaction gas are respectively introduced or a hydrogen gas is introduced as a carrier gas. I have.

A substrate 2 is arranged in a chamber 1, and the substrate 2 is fixed by a substrate holder 3. A cooling pipe 4 is passed through the substrate holder 3 in a horizontal direction. By flowing, for example, liquid nitrogen into the cooling pipe 4, the substrate 2 on the substrate holder 3 can be cooled. The cooling temperature is, for example, −50 ° C. to −150 ° C. when tungsten fluoride (WF ₆ ) is used as the compound material gas as described above, but this temperature can be changed depending on the pressure in the chamber 1. Things,
In short, the compound material gas condenses (adsorbs) on the surface of the substrate 2
The temperature may be set to such a value.

An excimer laser irradiation device 5 for irradiating a laser as an energy beam is disposed above the chamber 1. The excimer laser irradiator is, for example, a KrF excimer laser (wavelength 248 n).
m). The laser light emitted by the excimer laser irradiation device 5 reaches the inside of the chamber 1 through an upper glass window (not shown) of the chamber 1 and reaches the substrate 2. A mask 6 is provided between the excimer laser irradiation device 5 and the chamber 1.
Are arranged so that the substrate 2 is irradiated with laser light in a predetermined pattern.

Next, a method of forming a thin film using the above-described thin film manufacturing apparatus will be described.

First, the substrate 2 is placed and fixed on the substrate holder 3 in the chamber 1, and liquid nitrogen is passed through the cooling pipe 4 to keep the substrate 2 at a temperature of about -100.degree.
Then, WF ₆ gas as a compound material gas and H ₂ gas as a reaction gas are introduced into the chamber 1 at a flow rate of 200 to 300 sccm, and the inside of the chamber 1 is 10 to 300 tons.
Set to rr.

When the substrate 2 is cooled as described above, the WF ₆ gas existing near the surface of the substrate 2 is condensed (adsorbed) on the surface of the substrate 2 and the compound material W
An F ₆ liquefied layer 10 is formed. In the state where the WF ₆ liquefied layer 10 having a predetermined thickness (for example, 20 nm) is formed on the surface of the substrate 2 or in the process of attaching WF ₆ to the substrate 2, the excimer laser irradiation device 5 is used. Is operated to collect the excimer laser light emitted from the excimer laser irradiation device 5 and irradiate the substrate 2 through the upper glass window of the chamber 1. The energy of the excimer laser light was set to about 400 mJ, and one shot (20 to 30 ns) irradiation was performed a plurality of times.

When the excimer laser light is irradiated, WF ₆ is excitedly decomposed and reacts with the H _2, and W (tungsten) is formed only in the laser irradiated portion as shown in the following formula. A thin film made of W is formed in a predetermined pattern.

[0017]

Embedded image WF ₆ + 3H ₂ → W + 6HF

The produced hydrogen fluoride (HF) is
The gas is discharged from the chamber 1 through an exhaust passage (not shown).

The above method has the following advantages. That is, such methods, since the WF ₆ be those for forming a film from a WF ₆ attached to the surface of the substrate 2 is WF ₆ density on are present because the substrate 2 in attached state is high, W The film formation speed can be increased. Specifically, the film forming rate per shot of the excimer laser is improved, and the film forming speed of the W film is increased. When the substrate 2 is cooled to about −100 ° C., a reaction at a low temperature is forced, but the excitation does not necessarily occur by the thermal energy of the laser, and the photons of the laser directly act. Therefore, it is considered that the substrate cooling does not have a bad influence on the film forming rate because the substrate may be excited by the heat.

Further, when the above-described excimer laser beam is irradiated toward the substrate 2, WF ₆ adhering to the surface of the substrate 2 reacts with H ₂ to form W.
Since the W is generated in a state where F ₆ is attached to the substrate 2, the dispersion of the W is suppressed. Therefore, the W film is formed without having a spread with respect to the spot position of the excimer laser, and the transfer accuracy in the beam pattern can be increased.

Further, since such a film forming method has the above-mentioned advantages, it can be suitably used for manufacturing a photoelectric conversion device for a micromachine.

A photoelectric conversion device for a micromachine generates a high voltage in a very small area. As schematically shown in FIG. 2, for example, a photovoltaic element made of crystalline Si (p-layer on top) (Or n-layer) 20 ...
And the W layer 21 connects the upper p-layer (or n-layer) of the photovoltaic element 20 and the lower n-layer (or p-layer) of the adjacent photovoltaic element 20 with the W film 21. Must be connected in series. However, the series connection of the photovoltaic elements 20 by the W films 21 cannot be performed in a planar manner, and the portion to be connected to the upper layer side of the photovoltaic element 20 is connected to the upper layer side and connected to the lower layer side. It is necessary to form the W film 21 at a spatially determined position, for example, a portion to be formed is a lower layer side portion.

According to the method of this embodiment , the WF ₆ gas existing near the surface of the photovoltaic element 20 is cooled and condensed on the portion of the surface of the photovoltaic element 20 to be connected. (Adsorption). The excimer laser light is irradiated in a state where WF ₆ is adhered to a portion to be connected on the surface of the photovoltaic device 20 in this manner, so that a portion to be connected on the upper layer side of the photovoltaic device 20 is formed. The adhered WF ₆ forms a W film on the upper layer side,
The WF ₆ adhered to the portion to be connected on the lower layer side forms a W film on the lower layer side, and the W film 21 is formed at a spatially determined position with high speed and high transfer accuracy. Will be. That is, the space selectivity of film formation is improved.

In the manufacture of the above-described photoelectric conversion device for micromachines, a laser beam may be irradiated in a predetermined pattern using a mask. However, when the device surface does not have a planar shape, FIG. As shown in the above, three-dimensional scanning with a laser beam may be performed.

In this reference example , a KrF excimer laser was used as the excimer laser irradiation device 5,
However, the present invention is not limited thereto, and an ArF excimer laser or the like may be used, or may be determined according to the compound material used. As described above, by exciting the reaction material using the excimer laser beam, the thermal influence on the underlying layer on which the photovoltaic element and the like are formed is reduced. Further, it is possible to use a heat-sensitive resin or the like as the substrate. Of course, the energy beam is not limited to an excimer laser, and another laser beam or another energy beam such as ultraviolet light may be used.

[0026] Here, in the embodiment of the present invention, using the ion-<br/> gun or the like, the ionized hydrogen gas, by implanting the condensation (attached) with compounds in the material, a compound material of condensed state Hydrogen can be present not only on the surface of the compound but also in the compound material in the condensed state to enhance the film formation reaction. Further, in this embodiment, WF ₆ is used as the compound material gas. However, the present invention is not limited to this, and other compound materials that are in a gas phase at room temperature and condensed by cooling (not limited to metal compound materials) may be used. Good thing.

The minimum spot (or line) that can be drawn by an excimer laser is limited to about several μm due to the resolution limit due to interference of light. However, if a line pattern or the like is formed by using interference fringes caused by interference of light of a laser beam having coherence, it is possible to perform W film wiring with a thickness of several μm or less.

Further, the present invention can be applied not only to the manufacture of the photoelectric conversion device for a micromachine described above, but also to the modification of an electronic circuit.

(Embodiment 2) Next, a reference example of another embodiment of the present invention will be described.

In this reference example , W (CO) ₆ which is a metal carbonyl compound is used as a compound material,
Hydrogen ions are supplied as a reaction gas. W (CO) ₆ forms a solid phase at normal temperature. Therefore, as in the above-described first embodiment, cooling of the substrate is not particularly necessary. For example, powdered W (CO) ₆ is sublimated by a gasifier, and this gasified W (CO) By guiding ₆ into a room temperature chamber, W (CO) ₆ is condensed and adheres to the substrate surface. In this state, when excimer laser light is irradiated in the same manner as in the first embodiment, W (tungsten) is formed only on the laser irradiated portion as shown in the following formula, and a thin film made of W is formed in a predetermined pattern. Go.

[0031]

Embedded image W (CO) ₆ + nH ⁺ → W + iH ₂ O + jC _m H _{2m + 2}

In the film forming method in this reference example ,
As in the first embodiment, it is possible to increase the deposition rate of the W film and to increase the transfer accuracy in the beam pattern. As described above, although the substrate cooling is not particularly required, for example, when the substrate temperature needs to be maintained at a constant temperature equal to or lower than the normal temperature, the substrate cooling may be performed.

Further, in this reference example , W (CO) ₆ is shown as the metal carbonyl compound. However, the metal carbonyl compound is not limited thereto, and chromium carbonyl (Cr (CO) ₆ ), molybdenum carbonyl (Mo (CO) ₆ ), iron Carbonyl (Fe (C
O) ₅ ) or the like, which can be gasified by sublimation or the like and supplied as a compound material gas into the chamber.

In the reference examples of the first and second embodiments described above, the compound material gas is introduced into the chamber 1 so that the compound material adheres to the surface of the substrate. A liquid compound material may be placed on the substrate, and the liquid compound material may be attached to the substrate surface by, for example, spin coating. Note that the second implementation
In the case of the form , as described above, the ionized hydrogen gas is injected into the condensed (adhered) compound material using an ion gun or the like, thereby condensing not only on the surface of the condensed compound material but also on the surface. It is desirable that hydrogen be present in the compound material in the state to enhance the film formation reaction.

[0035]

As described above, according to the present invention, the density of the compound material on the substrate can be increased to increase the film forming rate. Furthermore, since a thin film is formed without spreading with respect to the spot position of the energy beam, the effect that the transfer accuracy in the beam pattern can be increased is also exhibited.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view showing a schematic configuration of a thin film manufacturing apparatus for performing a thin film forming method of the present invention, and FIG. 1B is an enlarged view of a portion indicated by an arrow A in FIG. FIG.

FIG. 2 is a cross-sectional view showing a photoelectric conversion device for a micromachine manufactured using the thin film forming method of the present invention.

[Explanation of symbols]

 Reference Signs List 1 chamber 2 substrate 3 substrate holder 4 cooling pipe 5 excimer laser irradiation device 6 mask

────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI H01L 21/3205 H01L 21/88 B (56) References JP-A-6-252233 (JP, A) JP-A-4-80367 ( JP, A) JP-A-4-63282 (JP, A) JP-A-2-209483 (JP, A) JP-A-62-242417 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , (DB name) H01L 21/285 C23C 16/48 C23C 16/44 H01L 21/205

Claims (2)

(57) [Claims] A step of depositing a compound material on a surface of a substrate, and bombarding the compound material with ionized hydrogen gas.
And a step of forming a thin film by reacting the hydrogen gas with the compound material with an energy beam. 2. a step of adsorbing or condensing a compound material gas in a reaction chamber on the surface of the substrate by cooling the substrate to attach the compound material to the surface of the substrate;
Implanting ionized hydrogen gas into the material,
Reacting hydrogen gas with the compound material with an energy beam to form a thin film.