JPS5928632B2 - dry etching equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dry etching apparatus that uses a laser beam to form a solid phase reaction product film on a metal surface.

A conventional dry etching apparatus is shown in FIG.

In this figure, 1 is an oxygen-acetylene flame generator, 2 is an oxygen-acetylene flame, 3 is a metal material, and 16 is a predetermined film forming pattern. heating the metal material 3 by the oxygen-acetylene flame 2 injected from the oxygen-acetylene flame generator 1;
The reaction rate of the metal surface with oxygen in the gaseous state in the atmosphere is increased to form a film of a solid phase reaction product on the surface. Oxygen-acetylene flame 2 includes Co, H2, C
A jet of high temperature mixed gas of O2, H2O and O2,
When the oxygen-acetylene flame 2 impinges on the surface of the metal material 3, the thermal energy of the gas is transferred to the metal. The oxygen-acetylene flame 2 injected near the predetermined film-forming region flows along the surface of the metal material 3, so that it is heated over a considerably wider area than the predetermined film-forming figure 16, and the heated metal material 3 has a metal layer on its surface. An oxide film is formed.

High-temperature atomic, molecular and ionized gas jets, such as the oxygen-acetylene flame 2, are difficult to control and impossible to focus into a small spot, and their power density is low. Conventional dry etching equipment heats a predetermined film-forming pattern 16 with a jet of high-temperature mixed gas such as an oxygen-acetylene flame 2 with a large heating area and low power density. It is impossible to heat only the surface layer of the metal material 3), and unnecessary areas of the metal material 3 are also heated, so a film is formed on surfaces other than the predetermined film formation pattern 16, resulting in a large amount of distortion due to heat. It was hot.

This invention was made to eliminate the drawbacks of the conventional ones as described above, and by using a CO2 laser beam as a metal surface heating source, only the surface layer of a predetermined film forming pattern 16 can be heated with a high power density heat source. It is an object of the present invention to provide a dry etching apparatus capable of heating a metal material 3 and forming a film of a reaction product with almost no distortion (deformation) occurring on the metal material 3.

This invention will be explained below. FIG. 2 shows an embodiment of the present invention, where 11 is a CO2 laser oscillator, 12 is a CO2 laser oscillator, and 12 is a CO2 laser oscillator.
13 is a reflector that guides the laser beam to the film-forming area; 14 is a device that prints reaction product seeds at the starting end of a series of film-forming figures; This is a printing device for reaction product species (coating).

As the seed used, for example, a mixed solution of Fe2O3 powder and a binder is used, and this is attached to the surface of the metal material 3. By arranging the discharge poles of the CO2 laser oscillator 11 so that the plane perpendicular to the laser optical axis of the glow discharge space of the CO2 laser oscillator 11 has an elongated rectangular shape, the laser emitted from the CO2 laser oscillator 11 can be The cross-sectional shape (near-field image) of the beam 15a can be made into an elongated rectangle.

The laser beam control device 12 is composed of two cylindrical lenses arranged orthogonally to each other and a position adjuster, and the position of each cylindrical lens can be adjusted. FIG. 3 shows a diagram of the principle of the laser beam control device. In FIGS. 3A and 3B, FIG. 3A is a plan view, FIG. 3B is a side view,
The traveling direction of the laser beam 15a is the Z axis, and the cross section of the beam perpendicular to the Z axis is a rectangle with one side XO and the other side YO. Let D1 be the distance between the cylindrical lens 12a having a focal length Fa and the cylindrical lens 12b having a focal length Fb. Laser beam 15a0
The x and y components are as shown in the figure. The X and y components Xl and yl of the laser beam at the distance D2 from the cylindrical lens 12b are as follows.

By adjusting the distances between the cylindrical lenses 12a and 12b and the metal material in this way, it is possible to shape the heat source into an arbitrary rectangular shape on the surface of the metal material. FIG. 4 shows the configuration of the reaction product species printing device 14, which includes a mask 14a cut out in a predetermined shape, a position adjuster 14b for disposing this mask at the starting end of the film forming figure 16, and a reaction product species printing device 14. It is comprised of a sprayer 14c that sprays a mixed solution of powder and binder in the form of a spray.

The mask 14a is arranged at the starting end of the film forming figure 16 by the position adjuster 14b. By introducing high-pressure gas into the gas transport path 14c1 of the injection nozzle constituting the sprayer 14c, the reaction product mixed solution introduced into the liquid transport path 14c2 becomes atomized, and is sprayed together with the gas at the starting end of the film-forming figure 16. The reaction product mixture solution is sprayed and adheres to the starting end of the film-forming figure 16 in the pattern cut out of the mask 14a (printing).
do. The solvent in this printed reaction product mixture solution is vaporized, and the reaction product mixture 17a is physically coated on the starting end of the film-forming figure 16. The absorption rate of a substance for a CO2 laser beam with a wavelength of 10.6 μm is inversely proportional to the DC electrical conductivity of that substance, so the absorption rate of various metal materials is extremely low, but the absorption rate of metal reaction products is extremely high (800 μm). /
)that's all). Now, referring again to FIG. 2, the rectangular laser beam 1 controlled by the laser beam controller 12
5b is guided by the reflector 13 and absorbed by a film of the reaction product mixture 17a printed by the reactive product species printing device 14 at the beginning of the film pattern 16.

The light energy absorbed there is converted into thermal energy. This thermal energy is diffused and heats the surface of the metal material 3 near the laser beam irradiation surface to a high temperature. The surface of the metal material 3 heated to a high temperature reacts with electronegative elements such as oxygen, sulfur, or halogen in the atmosphere, and a solid phase reaction product film grows on the surface. This is exactly
When the phosphorus and sulfur at the tip of a pine stick burns, the heat of combustion causes the wood at the shaft to reach a combustion temperature, similar to the development of wood burning. By relatively moving the metal material 3 and the laser beam 15b, the metal surface area on which reaction products are formed is expanded. When a dense metal oxide film is formed, metal atoms (as ions) diffuse from the metal monoxide interface to the oxide vapor phase interface, and a new oxide lattice is assembled at the oxide vapor phase interface.

When the interfacial reaction rate is large and thermodynamic equilibrium is reached at the interface, the equivalent growth rate of the oxide layer is Dn/Dt when the movement of charged particles in the oxide layer, that is, the progress of oxidation is dominated by volume diffusion. is Waguri E. rO) According to theory, it is expressed here.

When the temperature T is constant, the oxidation rate is inversely proportional to the thickness of the oxide layer, and the thickness δ of the oxide film is determined by the parabolic law δ2−Kpt+C(
Kp, C: constant). When the thickness δ of the oxide film is constant, the oxidation rate is proportional to the temperature T. That is, by heating the oxide film, the growth rate of the oxide film can be increased. FIGS. 5A and 5B show explanatory diagrams of the formation state of reaction products and the temperature distribution on the metal surface.

As shown in FIG. 5a, when a long and narrow laser beam 15c having a width y1=Yb-Ya is continuously irradiated at a variable velocity Vy, most of the irradiated laser beam is absorbed by the reaction product 17. However, the thickness δ of the reaction product 17 directly under the irradiation surface of the laser beam 15c is 2δ≧α−12 to 5 μm (
However, the moving speed Vy is set so that α is the absorption coefficient of the reaction product with respect to the laser beam.

The absorbed light energy is converted into thermal energy.
This thermal energy is diffused and the vicinity of the laser heat source 15c is also heated. The temperature distribution on the y-axis (on the metal surface line) is like the curve 18 shown in Figure 5b, where the temperature T is maximum at y=Yb, and the temperature gradient δT/ when y<Ya.
δy becomes larger than the temperature gradient −θT/θy when y>Yb. However, it is necessary to keep the temperature at y-Yb below the melting point of the reaction product 17. According to Wagner's theory, the reaction rate increases by increasing the temperature of the reaction product 17. Further, the reaction rate is inversely proportional to the thickness δ of the reaction product 17. Therefore, the thickness δ of the reaction product 17 in the region y<Ya, which is indirectly heated by thermal conduction, increases rapidly as y increases. Ya≦y
In the region ≦Yb, the reaction product 17 is directly heated by the laser beam to a high temperature (below the melting point), so the reaction rate is high and the thickness δ of the reaction product 17 increases. In the region where y≧Yb, the temperature gradient θVOy becomes negative, the temperature decreases as y increases, and the reaction product 1
Since the thickness δ of the reaction product 17 is relatively thick, the reaction rate in this region is low, and the thickness δ of the reaction product 17 tends to gradually become saturated. In this way, the CO2 laser 15a
can be shaped into any rectangular heat source with high power density by the laser beam control device 12, so the amount of heat diffusion of the metal material 3 can be reduced. Therefore, the thermal strain generated in the metal material 3 is minute. Further, since the reaction product mixture is printed at the starting end of the film-forming figure 16 by the reaction product species printing device 14, the laser beam can be efficiently absorbed from the initial stage of the film-forming process, and stable film-forming process can be performed. In addition, in the above embodiment, the laser beam control device 1
2 is shown in which two cylindrical lenses 12a and 12b are provided, but a cylindrical mirror may also be provided.

Alternatively, an equivalent rectangular heat source may be obtained by scanning a small circular beam with high power density focused on the layer of reaction products by a condenser at high speed (100 Hz or more). Further, when the present invention is applied to a steel material such as carbon steel, only the surface area of the steel material can be rapidly heated and rapidly cooled, so that surface hardening can be performed while forming an iron oxide film on the surface. As explained in detail above, according to the present invention, the laser beam emitted from the CO2 laser oscillator is shaped into a long and narrow rectangular heat source with high power density by the laser beam control device, while a reaction is generated at the starting end of the film formation pattern. Since the seed of the material is printed and the laser beam is guided to this, the CO2 laser beam heat source can be used efficiently, and stable dry corrosion (film formation) can be achieved with almost no thermal strain on the metal material. It will be done.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a conventional dry etching apparatus, Fig. 2 is a schematic diagram showing a dry etching apparatus according to an embodiment of the present invention, and Figs. 3A and 3B explain the principle of a laser beam control device. 4 is a schematic diagram of a reaction product species printing device, and FIGS. 5A and 5B are explanatory diagrams of the formation state of reaction products and temperature distribution diagrams on metal surfaces. . In the figure, 3 is a metal material, 11 is a CO2 laser oscillator, 12
13 is a laser beam control device, 13 is a reflecting mirror, 14 is a reaction product species printing device, 15 is a laser beam, and 6 is a film forming pattern. Note that the same reference numerals or corresponding parts in the figures are indicated.

Claims (1)

[Scope of Claims] 1. A dry etching apparatus for forming a reaction product film on the surface of a metal material, comprising: a laser oscillator that emits a laser beam; and a laser that shapes the laser beam into an elongated rectangular heat source on the surface of the reaction product. a beam control device, a reflecting mirror that guides the laser beam to a predetermined location on the surface of the metal material, and a reaction product species printing device that prints reaction product seeds at the starting end of a film formation pattern on the surface of the metal material. A dry corrosion apparatus characterized by comprising: 2. A patent characterized in that the laser beam control device is composed of two cylindrical lenses arranged perpendicular to each other and a position adjuster for adjusting the position of each cylindrical lens. A dry etching apparatus according to claim 1. 3. The reaction product species printing device includes a mask cut out in a predetermined shape, a position adjuster for arranging this mask at the starting end of a film-forming pattern, and a fine powder of the reaction product and a binder solution placed in the cutout part of the mask. 2. The dry etching apparatus according to claim 1, further comprising: a sprayer for spraying a mixed solution of a mixture of