JP2664723B2 - Laser annealing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Overview] Regarding a laser annealing apparatus, an object of the present invention is to provide a laser annealing apparatus capable of reducing the distance between an objective lens and a sample and using a high magnification objective lens having a short focal length. For the purpose, laser annealing equipment equipped with a surface observation mechanism,
It has an observation lens system, an image transfer lens system, and a lens system for condensing and focusing laser light, and forms a transfer image of a sample between the observation lens system and the image transfer lens system. An image forming point is formed, a wavelength selection plate is inserted between the observation lens system and the image transfer lens system, and laser light and visible light are separated and combined.

[Industrial applications]

The present invention relates to a laser annealing apparatus, and more particularly to a laser annealing apparatus having a surface observation mechanism capable of observing a sample surface in a minute area.

A laser annealing apparatus provided with a surface observation mechanism focuses laser light and irradiates the laser beam to a workpiece, and at the same time, observes a surface state of the workpiece. In recent years, a device having a multilayer structure has been devised as a technology for improving the degree of integration of ICs and LSIs, and one of them is the SOI technology. This S
One of the OI technologies is a laser recrystallization method. This laser recrystallization method melts and recrystallizes a non-single-crystal semiconductor layer by irradiating a non-single-crystal semiconductor layer (for example, a poly-Si layer) formed on an insulating film with laser light. It is. The device used at this time is a laser annealing device.

In order to improve the crystallinity of the melt-recrystallized recrystallized semiconductor layer, it is necessary to perform recrystallization while observing the surface of the semiconductor layer at the time of melting, and a laser capable of performing recrystallization while observing the surface An annealing apparatus is required.

[Conventional technology]

FIG. 3 is a schematic view of an example of a conventional laser annealing apparatus.

In this figure, 1 is an eyepiece, 2 is a total reflection mirror, 3
Is a two-wavelength selection plate called a dichroic mirror (a dichroic filter may be used. In this case, however,
The part that is reflected or transmitted by the dichroic mirror 3 is changed to a system that transmits or reflects the light in the opposite direction, and the direction and position of the objective lens 5 are also rotated by 90 ° in the figure and come to the left. ), 4 is a laser beam, 5 is a condenser lens, which can function as an objective lens. A is the focal position of the condenser lens 5, and B is
Is a focus position of the laser light 4, and X is a shift between a focus position A of the collective lens 5 and a focus position B of the laser light 4.

In this conventional apparatus, the wavelength of the laser beam 4 is selected by the two-wavelength selection plate 3, the laser beam 4 is condensed by the condenser lens 5, and the sample (not shown here, ), And the state change of the sample surface was observed by using the condenser lens 5 as an objective lens. However, in this apparatus, since the laser beam 4 oscillated from a laser oscillation tube (not shown) has a spread angle, the focal position B of the laser beam 4 and the focal position A of the condenser lens 5 (the observation position of the sample) In general, the sample is arranged near the focal length of the objective lens in order to increase the magnification.
Thus, there is a problem that it is difficult to observe the sample surface. Here, in order to simply shorten the shift X, if a plurality of lenses are provided below the point B in the drawing, the shift X becomes shorter and the magnification at the time of observation can be increased. However, the depth of the illuminated point at the time of observation becomes shallower (shorter) due to the increase in the magnification, and eventually the sample surface becomes blurred at the time of laser irradiation.

As a means for solving the above problem, the following method can be considered. Hereinafter, a specific description will be given with reference to the drawings.

FIG. 4 is a schematic diagram showing another example of a conventional laser annealing apparatus.

3, the same reference numerals as those in FIG. 3 indicate the same or corresponding parts, 11 is an objective lens, A 'is a focal position of the objective lens 11, B' is a focus position of the laser beam 4, C is an objective lens.
11 focal lengths.

In this conventional apparatus, a two-wavelength selection plate 3 is inserted between an objective lens 11 for surface observation and a sample (not shown), and a laser beam 4 condensed by a condenser lens 5 is transmitted to the two-wavelength selection plate 3. Is used to irradiate the sample. In this device, the objective lens
It is possible to make the focal position A 'of the eleventh and the condensing position B' of the laser beam 4 coincide. Specifically, by appropriately changing the position of the condenser lens 5 in the left-right direction in the figure as indicated by D, the condenser position B 'of the laser beam 4 can be appropriately adjusted. That is, the distance between the focal position A 'of the objective lens 11 and the focal position B' of the laser beam 4 can be adjusted appropriately. It should be noted that the sample surface is arranged so that the focal position A 'of the objective lens 11 coincides with the condensing position B' of the laser beam 4.

[Problems to be solved by the invention]

However, in such a conventional laser annealing apparatus shown in FIG. 4, when the sample is heated to, for example, about 500 ° C., the two-wavelength selection plate 3 is not affected by heat. Since the lens 3 must be separated from the sample, a high-power objective lens having a short focal length C of the objective lens 11 cannot be used, and there is a problem that the magnification of the objective lens used is limited. Specifically, the distance between the sample and the objective lens 11 must be about 5 cm. Thereby, the magnification of the objective lens is limited to 5 times, and even if the magnification of the eyepiece is 10 times, only a magnification of about 50 times can be obtained. Even if the laser irradiation area is 50 μm square, it can only be expanded to 2.5 mm square. In fact, I want a magnification of about 200 times.

Therefore, an object of the present invention is to provide a laser annealing apparatus that can reduce the distance between an objective lens and a sample and use a high-magnification objective lens with a short focal length.

[Means for solving the problem]

In order to achieve the above object, a laser annealing apparatus according to the present invention includes, in a laser annealing apparatus having a surface observation mechanism, an observation lens system, an image transfer lens system, and a laser light focusing / focus correction lens system. Having an image forming point for forming a transfer image of a sample between the observation lens system and the image transfer lens system, and a wavelength selection plate between the observation lens system and the image transfer lens system. The laser light and the visible light are inserted and separated and combined.

[Action]

In the present invention, an observation lens system, an image transfer lens system, and a lens system for condensing and focusing laser light are provided, and a transfer image of a sample is formed between the observation lens system and the image transfer lens system. An imaging point is formed, a wavelength selection plate is inserted between the observation lens system and the image transfer lens system, and the laser beam and the visible light are separated and combined.

Therefore, the distance between the objective lens and the sample can be reduced, and a high-magnification objective lens having a short focal length can be used.

〔Example〕

 Hereinafter, the present invention will be described with reference to the drawings.

FIG. 1 is a schematic view showing the configuration of an embodiment of a laser annealing apparatus according to the present invention.

In this figure, the same reference numerals as those in FIGS. 3 and 4 denote the same or corresponding parts, and 1a denotes an eyepiece (for example, f25mm,
× 10), 3a is a wavelength selection plate called a dichroic mirror (corresponding to the wavelength selection plate according to the present invention), 4a is, for example,
Ar laser light, 20 is a half mirror, 21 is an objective lens (for example, f42 mm, × 5), 22 is a lens for focus correction and light collection (for example, f100 mm, × 10, and light collecting and focus correction according to the present invention) 23a, 23b are image transfer lenses (for example, 23a is f20mm, × 4, 23b is f20mm, × 2, and corresponds to the image transfer lens system according to the present invention), and 24 is The sample, 25, is the observation light.

Here, the image forming position of the objective lens 21 is set to the point M (corresponding to the image forming point according to the present invention), and the image transfer lens 23a is appropriately arranged so as to form an image at the point M. The point N is an imaging position of the image transfer lens 23b, and the image transfer lens 23b is appropriately arranged so as to be coupled to the point N on the sample surface. The laser beam 4a has a function of processing the surface of the sample 24. The observation lens (corresponding to the observation lens system according to the present invention) includes an eyepiece 1a and an objective lens 21.

 Next, the operation principle will be described.

Laser oscillation tube (not shown here, for example,
Laser light 4a (for example, wavelength 5145) emitted from an Ar laser oscillation tube)
10, 10 W) have a certain spread angle, and the light transmitted through the lens 22 for condensing and focusing is reflected by the wavelength selection plate 3 a (here, the light of 5145 Å is transmitted, and the other is transmitted). ), And is reflected downward at the point M in FIG. At this time, the condensing and focus correcting lens 22 is moved left and right (point P) in the figure so that the condensing position is set to a preset M point.
Adjust by moving it to the appropriate position. The light condensed at the point M is condensed again at the point N on the surface of the sample 24 by the image transfer lenses 23a and 23b, and the sample 24 is processed by this light.

When observing the surface of the sample 24, the sample image at the point N is transferred to the point M by the image transfer lenses 23a and 23b, and the transfer image of the sample 24 image transferred to the point M is observed at the observation lens (objective lens 21). And can be observed through the eyepiece 1a). Specifically, a part of the observation light 25 from the observation light source (not shown) is reflected downward by the half mirror 20 in the figure and transmitted through the objective lens 21. The transmitted light is selected by the wavelength selection plate 3a (for example, transmits light other than 5145 °), and then passes through the image transfer lenses 23a and 23b to illuminate the surface of the sample 24. On the other hand, the reflected light from the surface of the sample 24 is transmitted to the lens 23 for image transfer.
The light passes through a and b, is selected by the wavelength selection plate 3a, and passes through the objective lens 21 and the half mirror 20. Then, the light is reflected leftward in the figure by the total reflection mirror 2 and passes through the eyepiece 1a, so that the surface of the sample 24 can be observed. At this time, the magnification at the time of observation is the product of the magnification of the eyepiece 1a, the objective lens 21, and the lenses 23a and 23b for image transfer (10 × 5 × 4 × 2 = 400 ×). Since the magnification of the normal observation lens system is the magnification of the eyepiece × the magnification of the objective lens, the objective lens of this embodiment is
If the magnification after 21 is the magnification of the objective lens, 5 × 4 × 2 =
40 times, which is substantially equivalent to using a high-magnification objective lens with a short illumination distance.

That is, in the above embodiment, the image forming point (M) for forming the transfer image of the sample 24 between the observation lens and the image transfer lens 23a.
Point), a lens for observation and a lens 23a for image transfer
The wavelength selection plate 3a is inserted between the two to separate and combine the laser light 4a and visible light, so that the objective lens 21 and the sample
The same effect as using a high-magnification objective lens with a short focal length by reducing the distance from the sample 24 can be expected, and observation of the surface of the sample 24 in a minute area can be performed.

In the above-described embodiment, the case where the wavelength selecting plate 3a is inserted between the objective lens 21 and the image forming point (point M) as shown in FIG. 1 to separate and combine the laser light 4a and the visible light will be described. However, the present invention is not limited to this, and the wavelength selection plate 3a includes at least the observation lens and the image transfer lens 23.
It is sufficient that the wavelength selection plate 3a is inserted between the imaging point (point M) and the image transfer lens system 34 as shown in FIG. The case of separating and synthesizing visible light may be used. The number of lenses for image transfer is not limited to two, but may be any number. In FIG. 2, reference numeral 33 denotes an observation lens system.

In the above embodiment, the case where the wavelength selection plate 3a is configured by a dichroic mirror has been described, but the present invention is not limited to this, and may be configured by a dichroic filter.

〔effect〕

ADVANTAGE OF THE INVENTION According to this invention, there exists an effect that the space | interval of an objective lens and a sample can be reduced and the sample surface of a micro area | region can be observed using a high magnification objective lens with a short focal length.

[Brief description of the drawings]

FIG. 1 is a schematic view of a laser annealing apparatus according to one embodiment of the present invention, and FIG. 2 is a schematic view of a laser annealing apparatus according to another embodiment of the present invention. FIG. 4 is a schematic view showing an example of the configuration of a conventional laser annealing apparatus. 1a ... eyepiece lens, 2 ... total reflection mirror, 3a ... wavelength selection plate, 4a ... laser beam, 20 ... half mirror, 21 ... objective lens, 22 ... lens for condensing and focus correction, 23a, 23b: Image transfer lens, 24: Sample, 25: Observation light.

Claims (1)

(57) [Claims] 1. A laser annealing apparatus having a surface observation mechanism, comprising: a lens system for observation, a lens system for image transfer, and a lens system for condensing and focusing laser light. Forming an image forming point for connecting a transfer image of a sample between the image transfer lens system and the image transfer lens system; inserting a wavelength selection plate between the observation lens system and the image transfer lens system; A laser annealing device configured to separate and combine the laser beams.