JPH04276063A - Laser-beam deposition method - Google Patents

Abstract

PURPOSE:To apply laser-beam deposition to even a target low in laser beam absorptivity such as metal by efficiently transmitting the energy of a laser beam to the target and increasing the deposition rate. CONSTITUTION:A laser beam 2 is introduced into a vacuum chamber 1 to irradiate a target 6 which is thereby vaporized, and the vapor is deposited on a substrate 8. In this case, the target 6 is irradiated with the laser beam 2 having the linearly polarized light at the incident angle equivalent or close to the Brewster angle of polarization to the P polarization with the electric field vector of the incident laser beam 2 parallel to the incident plane.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser vapor deposition method used to form a vapor deposited film on the surface of a member (substrate).

0002

2. Description of the Related Art Conventionally, there are various target evaporation means used to form a vapor deposited film on the surface of a member (substrate), including the use of a laser.

An example of a laser vapor deposition method using such a laser is shown in FIG.

In FIG. 9, 11 is a vacuum chamber, 12
1 is a laser beam, 13 is a convex lens, 14 is a laser introduction window, 1
5 is a reflecting mirror, 16 is a target, 17 is an evaporation particle,
18 is a substrate.

In this configuration, the laser beam 12 focused by the convex lens 13 is introduced into the vacuum chamber 11 through the laser introduction window 14.

[0006] The laser beam 12 that has entered the vacuum chamber 11 is treated with the following steps to prevent the evaporative particles 17 from adhering to the laser introduction window 14 and to prevent the laser beam 12 from being absorbed and diffused by the evaporative particles 17. It is refracted by the Cu mirror 8, and the laser incident angle is uniquely set to 60 degrees by the device, and the target 16 is irradiated.

[0007] Thus, the portion irradiated with the laser beam 12 flies out as evaporated particles 17 in the radial direction of the target surface and adheres to the substrate 18.

Incidentally, in recent years, it has become clear that the absorption rate of steel materials depends on the incident angle of the laser beam due to the influence of polarization, and techniques to apply it to laser hardening have been developed, but other No research has been done on the materials.

[0009] Therefore, the present inventors used Fresnel's formula to theoretically calculate the absorptivity of a CO2 laser with a wavelength of 10.6 μm for various ceramic materials. The results revealed that the absorption rate of ceramics is also affected by polarization, and that the incident angle of the laser beam that exhibits the maximum absorption rate varies depending on the material, even for the same ceramic material.

FIG. 2 shows the theoretical calculation results of the absorption rate for Al2O3.

As shown in FIG. 2, for S-polarized light in which the electric field vector (electric field) of the incident laser beam is perpendicular to the plane of incidence,
The absorption rate decreases monotonically as the angle of incidence increases. On the other hand, for P-polarized light in which the electric field vector of the incident laser beam is parallel to the plane of incidence, the absorption rate shows a maximum value at the Brewster angle, and the absorption rate decreases monotonically at an incident angle larger than the Brewster angle. .

0012

[Problems to be Solved by the Invention] However, in the conventional method, only consideration has been given to setting the laser beam at an incident angle that is not affected by the evaporation of the target, and the direction of polarization has not been taken into account.

Furthermore, in the conventional method, the incident angle of the laser beam is uniquely set by the device, and the laser beam is irradiated at the same incident angle for all materials.

Therefore, even if the P-polarized light has a Brewster's angle, depending on the material, the laser beam may be irradiated at an incident angle that deviates significantly from the Brewster's angle, making it difficult to efficiently transmit the energy of the laser beam to the target. There is a problem in that it is not possible to do so, and it has been a challenge to solve this problem.

[0015]

OBJECTS OF THE INVENTION The present invention has been made in view of these conventional problems, and an object of the present invention is to make it possible to efficiently transmit the energy of laser light to a target.

[0016]

[Means for Solving the Problems] The present invention provides a laser vapor deposition method in which a target is irradiated with a laser beam introduced into a vacuum chamber to vaporize the target and deposited on a substrate. It is characterized by a configuration in which the target is irradiated with P-polarized light whose electric field vector is parallel to the plane of incidence at an incident angle at or near Brewster's angle. The present invention is characterized by having a structure in which the target is irradiated with laser light in the direction of P-polarized light at a predetermined angle of incidence. There is.

[0017]

Effects of the Invention In the laser vapor deposition method according to the present invention, a linearly polarized laser beam is directed to a target at an incident angle at or near Brewster's angle in the direction of P-polarized light in which the electric field vector of the incident laser beam is parallel to the plane of incidence. Since the structure is such that the absorption rate of the laser beam is increased, the energy of the laser beam is efficiently transmitted to the target, and the deposition rate by the laser is further increased. Become. Further, even target materials such as metals that have a low laser absorption rate can be laser-deposited.

[0018]

[Embodiment] Fig. 1 shows an embodiment of the laser vapor deposition method according to the present invention, in which 1 is a vacuum chamber, 2 is a laser beam, 3 is a convex lens, 4 is a laser introduction window, and 5 is a vacuum chamber. is a reflection mirror made of Cu, etc., 6 is a target, 7 is a reflection mirror made of Cu, etc.
8 is an evaporated particle, and 8 is a substrate, which is different from the conventional laser evaporation method shown in FIG. By providing a moving mechanism and a rotating mechanism (not shown) to the convex lens 3 and the reflecting mirror 5, the incident angle of the laser beam 2 can be set to the Brewster's angle corresponding to the material of the target 6. It is in.

FIG. 3 shows that using the calorimetric method,
This figure shows the results of measuring the absorption rate of CO2 laser for Al2O3 (alumina). The sample used here is No. 1 in Table 1. As shown in column 1, it is a pressureless sintered body with a purity of 99% by weight, and the surface roughness is Ra0.11, Rm
The one with ax of 2.96 was used.

As a result, the incident angle dependence was in good agreement with the theoretically calculated values shown in FIG. And the angle of incidence is 0
At degrees, CO2 laser light is about 9% for Al2O3.
The absorption rate was 5%, but for S-polarized light, the absorption rate decreased as the incident angle increased, and at an incident angle of 60 degrees, the absorption rate decreased to about 30%.

On the other hand, for P-polarized light, the absorption rate increases as the incident angle increases, and at a Brewster angle of 30 degrees, the absorption rate was about 99%. At an incident angle larger than Brewster's angle, the absorption rate decreases monotonically as the incident angle increases, and at an incident angle of 60 degrees, the absorption coefficient decreases by approximately 5.
This would result in a drop below 0%.

Therefore, based on such absorptance characteristics, the laser beam is oriented in the direction of P-polarized light, in which the electric field vector of the incident laser beam is parallel to the plane of incidence, and the Al2 of the CO2 laser is
As a result of performing laser deposition with irradiation at a Brewster angle of 30 degrees with respect to O3, it was possible to obtain a deposition rate approximately twice as high as in the conventional case of irradiation at 60 degrees.

FIG. 4 shows the Si3 N4 of CO2 laser.
This shows the results of experimentally determined absorption rates for (silicon nitride). The sample used here is No. 1 in Table 1. 2
As shown in the column, a pressureless sintered body with a purity of 90% by weight or more, containing Al2O3 and MgO as binders, and a surface roughness of Ra0.37 and Rmax3.81 was used.

As a result, even in the case of Si3 N4, Al2
As in the case of O3, for S-polarized light, the absorption rate decreases as the angle of incidence increases, and at an angle of incidence of 0 degrees, the absorption rate is about 50%, but for P-polarized light, the absorption rate decreases as the angle of incidence increases. increased, and at an incident angle of 70 degrees, an absorption rate of about 72%, about 1.5 times that at an incident angle of 0 degrees, was obtained.

Similarly, FIG. 5 shows BN (boron nitride),
Figure 6 shows the CO of ceramics made of SiC (silicon carbide).
2 This shows the results of experimentally determined laser absorption rates. Here, the purity and surface roughness of the samples used are shown in Table 1.
No. 3, No. Shown in column 4.

Further, FIG. 7 shows the results of measuring the CO2 laser absorption rate of C (graphite), and FIG. 8 shows the results of measuring the CO2 laser absorption rate of Si (silicon). Here, as for silicon, crystal orientation (10
0) boron-doped p-type silicon wafer was used.

Since the Brewster angle and its absorption rate vary depending on the wavelength of the laser beam and the material, it is necessary to set the range of the incident angle depending on the material, but from these experimental results, the incident angle of the CO2 laser on Al2O3 10 to 50 degrees, angle of incidence to Si3N4 40 to 80 degrees, angle of incidence to BN 45 to 70 degrees, angle of incidence to SiC 10 to 70 degrees, angle of incidence to graphite 10 to 80 degrees, angle of incidence to silicon It was confirmed that when the angle was set between 40 and 85 degrees, a higher absorption rate was obtained, the energy of the laser beam could be efficiently transmitted to the target, and the deposition rate was significantly increased.

[0028]

[Table 1]

[0029]

As explained above, according to the present invention, the electric field vector of the incident laser beam is aligned in the direction of P-polarized light, which is parallel to the plane of incidence, at or near Brewster's angle, according to the present invention. Since the target is irradiated at the incident angle, it is possible to efficiently transmit the energy of the laser beam to the target, resulting in the effect of significantly increasing the deposition rate. Even if the target material has a low absorption rate for laser, etc., laser deposition is possible, which is a remarkable advantage.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an embodiment of a laser vapor deposition method according to the present invention.

FIG. 2 is an explanatory diagram showing the results of theoretical calculations of the absorption rate of CO2 laser for Al2O3.

FIG. 3 is an explanatory diagram showing experimental results of the absorption rate of CO2 laser for Al2O3.

FIG. 4 is an explanatory diagram showing experimental results of the absorption rate of CO2 laser for Si3 N4.

FIG. 5 is an explanatory diagram showing experimental results of the absorption rate of CO2 laser for BN.

FIG. 6 is an explanatory diagram showing experimental results of the absorption rate of CO2 laser for SiC.

FIG. 7 is an explanatory diagram showing experimental results of the carbon absorption rate of a CO2 laser.

FIG. 8 is an explanatory diagram showing experimental results of the absorption rate of CO2 laser for silicon.

FIG. 9 is an explanatory diagram showing a conventional laser deposition method.

[Explanation of symbols]

1 Vacuum chamber 2 Laser light 3 Convex lens 4 Laser introduction window 5 Reflection mirror 6 Target 7 Evaporation particles 8 Board

Claims (7)

[Claims] Claim 1: In a laser evaporation method in which a target is irradiated with a laser beam introduced into a vacuum chamber, the target is evaporated, and the target is deposited on a substrate. A laser vapor deposition method characterized in that a target is irradiated with P-polarized light at an incident angle at or near Brewster's angle. [Claim 2] CO2 laser light is oriented in the direction of P polarization.
2. The laser deposition method according to claim 1, wherein the Al2O3 target is irradiated at an incident angle of 0 to 50 degrees. [Claim 3] CO2 laser beam in the direction of P polarization 4
2. The laser deposition method according to claim 1, wherein the Si3N4 target is irradiated at an incident angle of 0 to 80 degrees. [Claim 4] CO2 laser beam in the direction of P polarization 4
2. The laser deposition method according to claim 1, wherein the BN target is irradiated at an incident angle of 5 to 70 degrees. [Claim 5] Direct the CO2 laser beam in the direction of P polarization.
2. The laser vapor deposition method according to claim 1, wherein the SiC target is irradiated at an incident angle of 0 to 70 degrees. [Claim 6] Directing the CO2 laser beam in the direction of P polarization
2. The laser vapor deposition method according to claim 1, wherein the graphite target is irradiated at an incident angle of 0 to 80 degrees. [Claim 7] The CO2 laser beam is polarized in the direction of P polarization.
2. The laser vapor deposition method according to claim 1, wherein the silicon target is irradiated at an incident angle of 0 to 85 degrees.