JP4008083B2 - Microfilm formation method using laser heating evaporation method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for forming a film having a minute area by intensively depositing fine particles generated by laser heating in a necessary place such as an IC or a display.
[0002]
[Prior art]
Conventionally, a laser ablation (deposition) method in which solids are melted and evaporated in a vacuum or controlled atmosphere using laser light energy as a heat source, and deposited on the entire surface of a substrate placed opposite to the evaporation position. It has been known. This method is a method of forming a film over the entire surface of the substrate, similarly to the vacuum deposition method, the sputtering method, and the ion plating method. Also, the solid in the crucible is evaporated by an induction heating method, etc., and the evaporated material is conveyed at a high speed by the carrier gas flowing in the nozzle having a minute cross-sectional area, and blown out from the tip of the nozzle to be a predetermined position on the substrate. A gas deposition method is also known, which is deposited on the substrate. In this method, a nozzle connected to the film formation chamber maintained at a lower pressure than the evaporation chamber is provided immediately above the crucible provided in the evaporation chamber, and the material evaporated by the gas flow generated by the pressure difference between the two chambers is atomized. The film is deposited on the substrate by being conveyed and blown out from the nozzle.
[0003]
[Problems to be solved by the invention]
The laser ablation (deposition) method has a purpose of forming a thin film on the entire surface of the substrate because the evaporation amount per unit time is very small and the evaporation surface is very small. However, it is very difficult to form a uniform film over a large area. Therefore, even if there is an advantage that most high melting point materials can be evaporated by using a laser having a large energy density, a thin film constituting an IC or the like. It is not adopted as a technology to form Further, it is not possible to directly form a film at a specific position.
[0004]
In addition, the gas deposition method has a drawback in that the nozzle is easily clogged because a large amount of particles are conveyed in a relatively long nozzle having a minute cross-sectional area by a gas that is not sufficiently laminar. Moreover, in order to melt and evaporate the entire solid in the crucible by an induction heating method or the like, the carrier gas must flow in the upward direction and the nozzle must be vertical, and the substrate mounted downward directly above the nozzle gas outlet. By moving the, there is a restriction that the deposition position of the film must be determined, and a plurality of films cannot be produced at the same time. Further, due to heat resistance and evaporation problems of the crucible material and the like, the high melting point solid material cannot be evaporated.
It is an object of the present invention to provide a method capable of reliably transporting particles and forming a high melting point material relatively quickly, and capable of forming a minute film at a predetermined position simultaneously or sequentially, and an apparatus suitable therefor. It is the purpose.
[0005]
[Means for Solving the Problems]
In the present invention , the above object is to form a solid to be evaporated in a flat plate shape, and to irradiate one or more portions of the surface with laser light while flowing an inert gas in a laminar flow along the surface of the solid. This is accomplished by directly transporting the vaporized particles in the laminar flow and depositing them at a predetermined position in a minute area . Further, by changing the deposition position by changing the irradiation position of the laser beam, film formation can be performed sequentially or simultaneously at different positions. It is possible to control the size of the particles by changing the condensing size of the laser beam. A high-purity inert gas such as He, Ar, or N ₂ is used as the inert gas, and an inorganic material such as a metal, alloy, or ceramic is used as the solid. In the method of the present invention, the transparent glass plate and the plate-like solid surface are arranged in parallel with each other with a gap for flowing an inert gas, and a nozzle opening is provided on one side of the gap and the opposite side. Provided with an inert gas inlet, a nozzle formed so that the inert gas flowing on the surface of the solid becomes a laminar flow, and a laser light source for irradiating the surface of the solid via the transparent glass It can be conveniently carried out by the apparatus.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 1 denotes a vacuum chamber 2 that is evacuated and provided to face a plate surface of a substrate 3 such as a Si plate that forms a microfilm. An inert gas source is connected to an inert gas inlet 10 at one end of the nozzle 1 via a connecting pipe 9, and an inert gas whose pressure and flow rate are adjusted is supplied from the nozzle opening 4 to the substrate 3. It was blown out toward the plate surface.
[0007]
The nozzle 1 is made of glass and has a rectangular cross section as shown in FIG. 2, and a peripheral surface of the nozzle opening 4 side is cut out as shown in FIG. 3 to provide the solid 5 there. The solid 5 has a surface 5a formed in a flat plate shape. The surface 5a and the wall surface 1a of the nozzle 1 facing the surface 5a are parallel to each other to form a gap 11 between parallel nozzle passages. The solid 5 was held in place at a fixed position by a stainless steel holder 6 provided along the nozzle 1. The surface 5 a of the solid 5 is irradiated with laser light 7 from a laser light source 8 through the glass wall surface 1 a of the nozzle 1. One or a plurality of the light sources 8 are prepared, and the light collection size and the light collection position can be arbitrarily adjusted .
[0008]
The cross-sectional shape of the nozzle 1 may be any shape that does not impair the laminar flow on the surface 5a of the solid 5 on the nozzle opening 4 side. For example, the connecting tube 9 side may be formed thick as shown in FIG. The material of the nozzle 1 only needs to have a portion that can transmit the laser beam 7 without loss, and the other portions can be formed of a material that does not emit impurities. For the laser beam 7, a second harmonic of an Nd: YAG pulse laser or the like is used, and the beam waist diameter is adjusted to be focused to, for example, 0.1 mm. Further, it is advantageous to install the substrate 3 so as to be movable without changing the distance from the nozzle opening 4 in order to form a thin line, for example. The solid 5 can be made of an inorganic material that can be solidified, such as Cu, Ni, various high melting point metals, alloys, and ceramics.
[0009]
The apparatus of the illustrated embodiment will be described in detail. In the apparatus of FIG. 1, the inner diameter of the nozzle opening 4 of the nozzle 1 is a rectangle of 0.3 × 10 mm, and the lower side surface of the nozzle opening 4 is, for example, 10 mm wide and 10 mm long. It is cut and placed there and supported by a holder 6 with an ingot-like solid 5 such as Cu, Ni, etc. of 10 mm × 10 mm × 3 mm. Above the surface 5 a of the solid 5 that is formed smoothly and above the nozzle opening 4 A parallel space was formed between the sides. The surface 5a is irradiated with laser light 7 through a transparent side surface above the nozzle 5, and the light is emitted from a light source 8 of a laser oscillator provided in the vacuum chamber 2 as shown in FIG. Then, it is guided to the solid 5 through the expander 12, the mirror 13, the galvano 14, and the F-0 lens 15. In the example shown in FIG. 5, the nozzle 1 is provided horizontally, and the Si substrate 3 is provided vertically at a position 0.5 mm in front of the nozzle opening 4, and the substrate 3 is moved in the plane direction (X− Y direction). The light source 8 of the laser oscillator is controlled by an external laser power source 17 and a Q switch controller 18 to emit an Nd: YAG CW-Qsw green laser having a wavelength of 532 nm. The movement in the X-Y direction is adjusted by the driver 20 and the Y-driver 21 so that the film formation state of the substrate 3 can be monitored by light projection from the light source 22 and photographing by the CCD camera 23. For example, when the Q switch is used, the laser beam 7 emits light having a pulse energy of 3 mJ, a repetition frequency of 10 to 12 kHz, a pulse width of 250 ns, a peak power of 12 kW, a beam diameter of 3.0 mm, and the focal length of the lens 15 is For example, it is adjusted to 100 mm, and the laser beam 7 is focused on the surface 5 a of the solid 5 with a spot size of 0.1 mm in diameter.
[0010]
When the inside of the vacuum chamber 2 is evacuated to an appropriate vacuum and a flow of inert gas is flowed from the connecting pipe 9 so that the particles can be transported with sufficiently high purity and a laminar flow is obtained on the surface 5a of the solid 5, the nozzle opening 4 Since the upper and lower surfaces are flat and parallel, it flows as a laminar flow. When the solid 5 is irradiated with the laser beam 7 in this state, the irradiation spot is melted even if the solid 5 is a high melting point material. The fine particles evaporate and are directly carried by the laminar flow of the nozzle opening 4 and collide with the substrate 3 to be deposited as a film having a minute area. During the film formation, the substrate 3 is kept at several hundred degrees by a lamp or the like as necessary. Then, a post-treatment such as baking the formed microfilm in a reducing atmosphere may be performed.
[0011]
If the beam waist of the laser beam 7 is reduced, it is possible to form a very small film of several tens of μm or less. However, if necessary, a mask is formed on the substrate 3 by a conventional photolithography technique or the like, and the film is deposited. Later, the mask may be removed to complete the microfilm.
[0012]
The laser beam 7 may be configured to be scannable so that the irradiation position on the solid 5 moves, or a plurality of laser light sources are provided so that the plurality of laser beams 7 irradiate different positions on the solid 5 at the same time. Also good. By doing so, microfilms can be formed sequentially or simultaneously at different positions on the substrate 3, and as a result, the deposition rate is increased.
[0013]
Since the solid 5 evaporates as a melting container by the condensed laser beam 7, it is possible to avoid contamination by impurities due to evaporation of the conventional crucible material. By selection, most refractory materials can be used for the solid 5. Moreover, since there is an evaporation source in the nozzle 1, the position of the nozzle 1 can be moved even during laser irradiation by following the laser beam. Since the melted portion of the solid 5 by the laser beam 7 is very small, the nozzle 1 can be installed so that the surface 5a of the solid 5 is laterally or downward. Further, in the conventional gas deposition method, as described above, there was an accident that the nozzle was clogged and became inoperable. However, in the present invention, evaporation occurs in a sufficiently laminar inert gas in the nozzle 1. Since the distance from the evaporation point to the nozzle opening 4 is short, the evaporated particles are not agglomerated and the nozzle 1 is not clogged.
Examples of the present invention are as follows.
[0014]
[Example 1]
In the apparatus shown in FIG. 5, the second harmonic of an Nd: YAG laser having an energy density of 1.9 J / cm 2 / pulse and a repetition frequency of 10 kHz as laser light 7, N ₂ gas as an inert gas, and solid 5 Using a Cu ingot, the laser beam waist diameter is set to 100 μm, the inert gas flow rate is set to 10 l / min, and the shape of the nozzle opening 4 is set to a rectangle of 10 mm × 0.3 mm. A Si substrate 3 was disposed. By operating this apparatus, it was possible to form a 1 mm × 0.2 mm ultrafine Cu film on the surface of the substrate 3 at a rate of 200 Å / sec.
[0015]
[Example 2]
5 was operated with the same settings as in Example 1, and the substrate 3 was moved 15 mm in one direction at 0.05 mm / sec. As a result, Cu ultrafine particles having a width of 0.3 mm and a length of 15 mm were obtained. A linear microfilm could be formed.
[0016]
[Example 3]
The apparatus of FIG. 5 was operated with the same settings as in Example 1 except that the solid 5 was an Ni ingot and the substrate 3 had holes with a diameter of 100 μm and an aspect ratio of 1 or more. In this case, Ni could be embedded in the hole.
[0017]
[Example 4]
The apparatus of FIG. 5 was operated with the same settings as in Example 2 except that the solid 5 was an Ni ingot, and the substrate 3 had a width of 100 μm, a length of 15 mm, and a groove with an aspect ratio of 1 or more. In this case, Ni could be embedded in the groove.
[0018]
[Example 5]
The apparatus of FIG. 5 was operated under the same conditions as in Example 1 except that the flow rate of the inert gas was 12.5 l / min and the substrate 3 was made of SiO ₂ . FIG. 7 shows the result of analyzing the 5 mm × 0.2 mm Cu ultrafine particles formed on the SiO ₂ substrate by Auger electron spectroscopy. This microfilm was baked at 400 ° C. for 80 min in an atmosphere of 5% H 2 / Ar and analyzed by Auger electron spectroscopy. As a result, the oxygen component decreased as shown in FIG. It was found that was obtained.
[0019]
The sizes in the X and Y directions of the microfilm formed on the substrate 3 when the size and shape of the nozzle 1 and the inert gas flow rate of N ₂ are changed using the apparatus of FIG. 5 are shown in FIG. It was street. In this case, the plots of ○ and □ are the film sizes in the X and Y directions when the nozzle 1 having the dimensions shown in FIG. 1 is used, and ● and ■ are when the nozzle 1 having the dimensions shown in FIG. 4 is used. The film forming conditions are the same as those in the first embodiment. According to this, it can be seen that the nozzle of the size and shape of FIG. 1 is suitable for forming a microfilm having a small aspect ratio, and the nozzle of FIG. 4 is suitable for forming a microfilm having a large aspect ratio. Further, the inert gas flow rate is preferably 10 l / min or more in the shape of FIG. 1, and is preferably 4 l / min or less in the shape of FIG.
[0020]
【The invention's effect】
As described above, according to the method of the present invention, since the solid is evaporated by the laser beam in the flow of the inert gas and the evaporated particles are conveyed directly toward the substrate, there is no clogging of the nozzle, and particularly, the high melting point. It can be formed relatively quickly by controlling the micro membrane of the material. By flowing a laminar flow along the surface of the solid and irradiating one or more places on the surface with laser light, it is possible to control a predetermined place with good controllability. deposition can effect is obtained, can be changed easily deposited position by changing the irradiation position, Ru can control the size of the evaporation particles by changing the focused size. Further, the transparent glass plate and the surface of the plate-like solid are arranged in parallel with each other with a gap for flowing an inert gas, a nozzle opening is provided on one side of the gap, and an inert gas introduction port is provided on the opposite side. And a device provided with a laser light source that irradiates the surface of the solid through the transparent glass and a nozzle formed so that the inert gas flowing on the surface of the solid becomes a laminar flow The solids can be easily exchanged, and the method of the present invention can be carried out appropriately and inexpensively.
[Brief description of the drawings]
FIG. 1 is a side view of an essential part of an apparatus for carrying out the method of the present invention. FIG. 2 is an enlarged cross-sectional view taken along line 2-2 in FIG. 1. FIG. 3 is an enlarged cross-sectional view taken along line 3-3 in FIG. 4 is a side view of the modified example of FIG. 1. FIG. 5 is an overall side view of the apparatus used for carrying out the method of the present invention. FIG. 6 shows the relationship between the nozzle shape, the inert gas flow rate, and the membrane size of the micromembrane. FIG. 7 is an analysis diagram of the composition of a microfilm formed according to the present invention. FIG. 8 is an analysis diagram of a composition after firing the microfilm of FIG.
1 nozzle, 3 substrate, 4 nozzle opening, 5 solid, 5a surface, 7 laser light, 8 laser light source, 10 inert gas inlet, 11 gap,

Claims (5)

A solid to be evaporated is formed on a flat plate, and an inert gas is flowed in a laminar flow along the surface of the solid while irradiating a laser beam to one or a plurality of locations on the surface, thereby evaporating particles to the layer A method for forming a microfilm using a laser heating evaporation method, wherein the film is directly transported by a flow and deposited at a predetermined position in a micro area. 2. The method for forming a microfilm using a laser heating evaporation method according to claim 1, wherein the deposition position is changed by changing an irradiation position of the laser term. 2. The method for forming a microfilm using a laser heating evaporation method according to claim 1, wherein the size of the particles is controlled by changing the condensing size of the laser beam. _2. The laser heating evaporation method according to claim 1, wherein the inert gas is a high-purity inert gas of He, Ar, or N ₂ , and the solid is made of an inorganic material of a metal, an alloy, or a ceramic. Microfilm formation method used. The transparent glass plate and the surface of the plate-shaped solid are arranged in parallel with each other with a gap for flowing an inert gas, and a nozzle opening is provided on one side of the gap and an inert gas inlet is provided on the opposite side. And a laser heating evaporation comprising a nozzle formed so that an inert gas flowing on the surface of the solid becomes a laminar flow, and a laser light source for irradiating the surface of the solid through the transparent glass. Method for forming a microfilm using a method.

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