JP2617040B2 - Polyhedral prism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for performing pattern CVD or etching using a laser beam such as an excimer laser.
The present invention relates to a polyhedral prism which is effective in making the intensity of an irradiation laser beam uniform, and a laser beam projector using the polyhedral prism.

[0002]

2. Description of the Related Art Laser CVD is known as a method for forming a circuit pattern on a substrate by utilizing the energy of laser light. As shown in FIG. 8, a mask 2 having a light-transmitting portion 2a corresponding to a circuit pattern is placed in front of a laser beam 1, and a reaction cell 6 is placed through a projection lens 4 placed in front of the mask 2. The circuit pattern formed on the mask 2 is projected on the substrate 8 in the inside. The material gas in the cell 6 is photolyzed by the laser beam, and the generated radicals are recombined on the substrate 8 to form a film. It is formed.
An excimer laser is well known as a laser beam used. However, since the intensity distribution of the light is not uniform and the energy distribution of the laser beam irradiated on the substrate is different, a film formed on the substrate is used. There was a problem that the thickness was not constant. The laser light is incident on the substrate 8 through the window 6a of the reaction cell and is irradiated onto the substrate 8. Photodecomposition reaction of the material gas occurs also in the vicinity of the window 6a, and radicals are recombined to form a film inside the window 6a. Is formed, and there is a problem that the transmission efficiency of laser light is deteriorated due to this film. For this reason, conventionally, as shown in FIG. 9, a fly-eye lens 3 is placed in front of the mask 2 to diffuse the laser light and to make the energy distribution of the irradiated laser light uniform.

[0003]

However, fly-eye lenses are difficult and expensive to manufacture. Furthermore, it is not possible to focus all of the light diffused by the fly-eye lens, and a high-power laser device is required in consideration of the loss. Therefore, there is a problem that the product cost is increased. The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to provide an inexpensive polyhedral convex prism capable of equalizing the light intensity distribution on the light focusing surface without using a fly-eye lens. It is an object of the present invention to provide a new laser beam projector using this lens.

[0004]

According to a first aspect of the present invention, there is provided a multi-sided convex prism having a light input / output surface opposed to a light input / output surface. , A band-shaped central plane extending perpendicular to the optical axis, and a plurality of sets of band-shaped inclined planes extending parallel to the central plane on both sides of the central plane and gradually increasing in inclination with respect to the central plane. Is formed on the other light entrance / exit surface, and extends in a direction orthogonal to the extending direction of each plane forming the first convex ridge surface, and is perpendicular to the optical axis. And a plurality of sets of band-shaped inclined planes extending parallel to the central plane on both sides of the central plane, and symmetrical to the central plane and gradually increasing in inclination. A ridge surface is formed, and the parallel light incident on one light input / output surface is The angle of the inclined plane forming the first and second convex ridges is set so that the light is emitted and converged on the optical axis into a rectangular shape matching the optical axis direction overlapping region of the two band-shaped central planes. It is something to set.

According to a second aspect of the present invention, in the polygonal convex prism according to the first aspect, the first convex ridge surface and the second convex ridge surface have the same shape, and the outgoing light has a substantially square shape on the optical axis. The surface is focused. In the third aspect, the first
A convex ridge surface having a convex ridge surface formed on the front side and a rear surface being a plane perpendicular to the optical axis; and a planar surface having the second convex ridge surface formed on the front side and a rear surface perpendicular to the optical axis. The second
By integrating the convex ridge surface prism with the back side of the prism, the polygonal convex prism according to claim 1 is constituted.

According to a fourth aspect of the present invention, in the polygonal convex prism according to the third aspect, the first convex ridge prism and the second convex ridge prism have the same shape, and the outgoing light has a square optical axis. Above, the surface is focused .

[0007]

[Action] According to claim 1-4, the light beam is dispersed into light beams of each crest surfaces constituting the light incident surface when it enters the polygon convex prism, the light flux dispersed upon exiting from the polygon convex prisms Each of the light beams is dispersed into a light beam for each ridge surface constituting the light exit surface, and all of the dispersed light beams converge on a converging surface on the optical axis. Then, the band-shaped central plane of the first convex ridge surface and the band-shaped central plane of the second convex ridge surface converge in a rectangular shape overlapping in the optical axis direction .

[0008]

Next, an embodiment of the present invention will be described with reference to the drawings. FIGS. 1 and 2 show a first embodiment of a polyhedral prism according to the present invention. FIG. 1 is a perspective view of the polyhedral prism, and FIG. 2 focuses light emitted from the polyhedral prism. It is explanatory drawing explaining a situation.

In these figures, a polygonal convex prism 1 is shown.
Numeral 0 denotes a pair of light entrance / exit surfaces 11 each having a square shape.
A, 11B. And one light entrance / exit surface is
A first (planar) flat surface 12 perpendicular to the optical axis L
a and a first plane 12 adjacent to both sides of the first plane.
a set of symmetric second planes 14a, 14 inclined with respect to a
a and the first plane adjacent to the outside of the second planes 14a, 14a.
The convex ridge surface 11A is composed of a total of five planes including a pair of third planes 16a, 16a having a symmetrical tangle shape which is further inclined with respect to the plane 12a. The other light input / output surface has a slightly different surface angle between the convex ridge surface 11A and the inclined plane.
The protruding ridge surface 11B has a shape close to a shape rotated around 90 degrees. That is, similarly to the convex ridge surface 11A, the convex ridge surface 11B also has the second planes 14b, 14b, and the third plane 16b, 1 whose inclination gradually increases on both sides of the first flat surface 12b having a tangle shape.
6b is symmetrically formed.

The inclined planes 14a, 14a, 16a, 16a forming the first convex ridge 11A and the inclined planes 14b, 14b, 16b, 1 forming the second convex ridge 11B.
Reference numeral 6b denotes a central plane 12 on the side of the first convex ridge 11A, which is provided at a predetermined position on the optical axis in front of the lens.
The angle is set such that a and a central plane 12b on the side of the second convex ridge surface 11B converge into a square A formed by overlapping in the direction of the optical axis L. That is, the first convex ridge surface 11A is parallel to the optical axis L.
When the light beam enters the lens 10 from the lens, the light beam enters the five planes (12a, 14a, 14a) constituting the convex ridge surface 11A when entering the lens.
a, 16a, 16) corresponding to a cross-section
Are dispersed into a number of light beams. Then, when each light beam is emitted from the second convex ridge surface 11B, five planes (12b, 14b, 14b, 16b, 16b, 16
The five light beams corresponding to b), that is, the 25 light beams in total, are dispersed, and all of these 25 light beams are separated by the central plane 12a of the first convex ridge surface 11A and the second convex ridge surface 11B. Square A, which is a cross section of a light beam transmitted through both central planes 12b
Considering the wavelength of the laser beam, the refractive index of the prism material (a function of the wavelength of the laser beam), and the thickness of the prism (the laser beam passage distance in the prism), the first convex ridge surface 8 which respectively constitute 11A and the second convex ridge surface 11B
Inclined planes (14a, 14a, 16a, 16a, 14
a, 14b, 16b, 16b) are set. Then, the light beam having been converged into a square shape is dispersed into 25 light beams having a square cross section by transmitting the light through the polyhedral prism 10, and then all the dispersed light beams are again converged into one. Therefore, the light on the focusing surface has no unevenness in intensity, that is, light having a smoothed intensity distribution. In the above-described embodiment, the light emitted from the polyhedral convex prism 10 is surface-focused in a square shape. However, the number of band-shaped planes, the width of the band, and the inclination angle of the inclined plane with respect to the central plane are changed. Accordingly, a light beam having an arbitrary aspect ratio can be formed regardless of the cross-sectional shape of the light beam incident on the lens.

FIG. 3 shows a second embodiment of a polyhedral prism according to the present invention.
A and 22B are brought into close contact with each other and integrated as a polygonal convex prism 20. Polyhedral convex prism 22A (22
B) shows the convex ridge surface 11A (11) of the first embodiment on the front side.
B), that is, the first plane 12a (12b)
And the inclined second planes 14a, 14a (14b, 14
b) and the inclined third planes 16a, 16a (16b,
16b) and a convex ridge surface 11C (11D), and the back side is a plane 11E perpendicular to the optical axis L. Then, the first planes 12a and 12b are overlapped at right angles to the optical axis direction, and the back sides are adhered to each other. In the second embodiment, the polygonal convex prism 22A (22
In the case of B), since only one surface needs to be processed with the convex ridge, the processing is easy, and the manufacturing is easier than the multi-surface convex prism 10 shown in the first embodiment. However, since there is a loss due to reflection of the front and back surfaces of light when passing through the contact surface,
There is a disadvantage that the light intensity is lower than that of the polyhedral prism 10.

In the polyhedral convex prism 10 (20) in the first and second embodiments, in order to converge the outgoing light on the optical axis L, the prism is inclined on the light incident surface side and the light emitting surface side. Although the planes have slightly different plane angles, the outgoing light can be substantially converged on the optical axis even if the light entrance / exit surfaces 11A, 11B (11C, 11D) have exactly the same shape.

FIGS. 4 and 5 show a reference example of a polyhedral prism according to the present invention. FIG. 4 is a perspective view of the polyhedral prism, and FIG. 5 shows how light emitted from a polyhedral lens is focused. FIG. This polygonal convex prism 30
Is a truncated cone as a whole, one of the light entrance / exit surfaces is a plane 11F perpendicular to the optical axis L, and the other light entrance / exit surface is a circular central plane 32 perpendicular to the optical axis L; The ring-shaped tapered surfaces 34, 36, 3 are formed around the outer periphery 32, and are more greatly inclined with respect to the circular center plane 32 as the outer one is formed.
8 and 11G. The surface angles of the tapered surfaces 34, 36, 38 are
The light emitted from 36 and 38 is set so as to be surface-focused on the optical axis L into the same circle B as the central plane 32.

That is, the light incident on the polygonal convex prism 30 from the plane 31 side in parallel with the optical axis L proceeds straight through the prism, but when exiting from the prism 30, the central plane 32 and the tapered surface 34, The light is dispersed into light fluxes corresponding to 36 and 38, and all of the dispersed light is focused on a circle B which is a cross section of light transmitted through both the plane 11F and the central plane 32. Since the tapered surfaces 34, 36, and 38 have the same meaning as a structure in which an infinite number of planes are continuously formed in the circumferential direction, the luminous flux converged into the circle B is transmitted through the polygonal convex prism 30. After being dispersed into an infinite number of light fluxes, the light is focused again. For this reason, the light on the converging surface has no more unevenness than that obtained in the first embodiment, that is, light having a more smoothed intensity distribution.

Further, since the tapered surface can be formed by grinding and polishing the corner portion in a state where the cylindrical prism material is rotated around the axis, it is more preferable to process the tapered surfaces 34, 36 and 38 as described above. It is easier to process the inclined plane in the embodiment, and the multi-sided convex prism 30 of the embodiment is easier to manufacture. In FIG. 5, the polygonal convex prism 30 is arranged so that light is incident on the plane 11F side, but may be arranged so that the convex ridge surface 11G side is the light incident side.

[0016] Figure 6 is participation of laser light projection apparatus according to the present invention
This shows an example, and is an apparatus using the polyhedral convex prism shown in the first embodiment. Reference numeral 40 denotes a beam expander optical system, which has a confocal point f and vertically diffuses a cylindrical lens 42 that diffuses light in the vertical direction, a lateral diffused cylindrical lens 44 that diffuses light in the horizontal direction, and converts the light into parallel light. And a collimator lens 46. The multi-sided convex prism 10 is disposed in front of the beam expander optical system 40, and a mask 50 on which a circuit pattern 52 is formed by a light-transmitting portion is disposed at the focal plane position of the multi-sided convex prism 10. An enlargement-side telecentric projection lens 60 for reducing and projecting the circuit pattern 52 forward is arranged in front of 50.

The excimer laser light having a horizontally-long rectangular cross section is expanded in the vertical and horizontal directions by passing through the beam expander optical system 40 to become a parallel light L ₁ having a square shape, and passes through the polygonal convex prism 10. As a result, the light is dispersed into 25 light beams, and is focused on the mask 50 in a square shape. And the circuit pattern 52 of the mask
The light beam L _2, which is dispersed and transmitted through the circuit pattern is projected onto a predetermined forward position (image plane position) is reduced and projected by the projection lens 60. At this projected position, all the light beams emitted from the projection lens are converged, and the energy of the laser light is the highest. Further, the laser light on this image plane is reflected by
After being dispersed into individual light beams and converged, the intensity distribution of the irradiation laser light is uniform on the projection plane (imaging plane).

In the laser beam projection apparatus shown in FIG. 6, the beam of laser light is expanded into a square shape by the beam expander optical system 40, but the polygonal convex prism 10 crosses the beam of laser light. If the expander optical system 4 is formed to have a size matching the surface shape,
Laser light can be directly incident on the convex polygonal prism 10 without using 0.

FIG. 7 is a sectional view showing an optical path in a reaction cell when the apparatus shown in FIG. 6 is used for pattern CVD.
In this figure, reference numeral 70 denotes a reaction cell disposed in front of the projection lens 60, and a window 72 made of synthetic quartz glass is provided at the opening of the reaction cell 70. A reaction gas (material gas) is sealed in the reaction cell 70, and a substrate 74 is disposed at a position where the projection lens 60 projects. Reference numerals 71a and 71b are an inlet and an outlet for the reaction gas.

The laser beam emitted from the projection lens 60 is focused on the substrate 74, and the circuit pattern 52 formed on the mask is projected on the substrate surface. Recombination and substrate 7
A film is formed on 4. In particular, the laser beam transmitted through the window 72 is dispersed into 25 beams, and the beams are hardly superimposed on each other.
The energy of the laser light in the vicinity of the position 2 is low in density, and does not have a sufficient energy density for photodecomposing the reaction gas. Therefore, there is no disadvantage that a reaction occurs near the window of the reaction cell and the window is fogged and the transmittance of laser light is reduced as in the related art, and high-efficiency laser CVD can be achieved. In addition, since the energy of the laser light focused on the substrate is smoothed, a film having a uniform thickness can be formed, and a product with high processing accuracy can be supplied at low cost.

In the above-mentioned reference example , the present invention is applied to a pattern C
Although the embodiment applied to the VD has been described, the invention can be applied to various techniques as follows. In other words, the Japan Society of Applied Physics in the spring and fall of 1990 reports a technique of omitting the formation of a resist in a lithography process when manufacturing a semiconductor and directly etching Si using an ArF excimer laser without using a resist. The present invention is also applicable to the Si resist etching using the laser.
At the same meeting, irradiating ArF excimer laser using NF ₃ gas and ultra-high molecular weight PMMA resist with resistance to fluorine, exposure and development were performed simultaneously, simplifying the lithography process in the semiconductor circuit manufacturing process. However, the present invention is also applicable to dry development of the resist for lithography. Similarly, at the Japan Society of Applied Physics in the spring and fall of 1990, a report was made on the circuit pattern etching of crystalline SiC using a KrF excimer laser, but the present invention is also applicable to this circuit pattern etching of SiC. Similarly, at the Japan Society of Applied Physics in the spring of 1990, a report was made on surface modification of a polymer material (for example, Teflon) using excimer laser light. Can also be used.

[0022]

As is apparent from the above description, according to the polyhedral convex prism according to the present invention, the luminous flux is dispersed into the luminous flux of each ridge forming the light incident surface when entering the polyhedral prism. When the light is further emitted from the polygonal convex prism, the dispersed light is dispersed into the light flux for each ridge surface constituting the light exit surface, and all the dispersed light fluxes are focused on the focusing surface on the optical axis. In addition, light having a high energy density with a smoothed intensity distribution on the focusing surface can be obtained.

Further it has been using the present invention to a laser beam projector
For example , the laser light is dispersed into a plurality of light beams by a polygonal convex prism and focused on a mask on which a pattern to be projected is formed, and the light beam transmitted through the mask is incident on the magnifying side telecentric projection lens in a dispersed state. Is emitted in a dispersed state from the projection lens and is positioned at a predetermined position on the optical axis (imaging plane)
Since the surface is focused and the pattern to be projected is projected on the surface, a projection pattern free from unevenness of light intensity can be obtained. In addition, if the laser beam is expanded into a predetermined shape using the beam expander optical system, the convex polyhedral lens can be formed into an appropriate size that is easy to process, so that the apparatus can be manufactured at low cost. . If the reaction cell is placed in front of the projection lens and the laser beam is made to enter from the window, the laser beam is transmitted through the window in a state of being dispersed into a large number of light beams, so the energy of the laser beam near the window is The conventional problem associated with the reaction gas reacting near the window is low. In addition, since the energy density of the laser beam is highest near the substrate located at the position corresponding to the imaging plane, multiphoton absorption decomposition occurs, and the material gas that does not absorb at the wavelength of the irradiation laser is also photodecomposed. Can be.

[0024] General laser output pattern is Gaussian, therefore the highest energy density in the center of the laser beam, it is difficult clean laser processing, polygon convex prisms (frustoconical type shown in claim 1-4 If the lens is used for pattern transfer, the energy density becomes uniform, so that a clean processed surface can be obtained even when used for thermal processing using a CO ₂ laser or a YAG laser .

[Brief description of the drawings]

FIG. 1 is a perspective view of an embodiment of a polygonal convex prism according to the present invention.

FIG. 2 is an explanatory diagram illustrating a state in which light emitted from a polygonal convex prism is focused.

FIG. 3 is a perspective view of a second embodiment of the polygonal convex prism according to the present invention.

FIG. 4 is a perspective view of a reference example of a polygonal convex prism.

FIG. 5 is an explanatory diagram illustrating a state in which light emitted from a polygonal convex prism is focused.

FIG. 6 shows a reference example in which the present invention is applied to a laser beam projector.
Diagram shown

FIG. 7 is a cross-sectional view illustrating a state in which laser light emitted from a projection lens is focused in a reaction cell.

FIG. 8 is a diagram showing the overall structure of a conventional laser beam projector.

FIG. 9 is a diagram showing the overall structure of a conventional improved laser light projector.

[Explanation of symbols]

10, 20, 30 Polyhedral convex prisms 11A, 11B, 11C, 11D Convex ridges 12a, 12b central planes 14a, 14b, 16a, 16b inclined planes 32 circular central planes 34, 36, 38 tapered surfaces Reference Signs List 40 beam expander optical system 42 vertical diffusion cylindrical lens 44 horizontal diffusion cylindrical lens 46 collimator lens 50 mask 52 circuit pattern to be projected pattern 60 telecentric projection lens f confocal

Claims (4)

(57) [Claims] 1. A convex prism having opposing light entrance / exit surfaces, one of the light entrance / exit surfaces has a band-shaped central plane perpendicular to the optical axis, and both sides of the central plane are symmetrical with respect to the central plane. A first convex ridge surface composed of a plurality of sets of strip-shaped inclined planes whose inclinations are sequentially increased is formed, and the other light input / output surface has an extension of each of the planes forming the first convex ridge surface. It consists of a band-shaped central plane extending in a direction perpendicular to the exit direction and perpendicular to the optical axis, and a plurality of sets of band-shaped inclined planes on both sides of the central plane, which are symmetrical with respect to the central plane and whose inclination is gradually increased. A second convex ridge surface is formed, and parallel light incident on one of the light incident / exit surfaces exits from the other light incident / exit surface to form a rectangular shape that matches the optical axis direction overlapping region of the two band-shaped central planes. The surface angles of the inclined planes forming the first and second convex ridges are set so that the surfaces converge on the optical axis. A multi-sided convex prism. 2. The method according to claim 1, wherein the first convex ridge surface and the second convex ridge surface have the same shape, and the outgoing light is substantially converged on the optical axis in a square shape. Polyhedral convex prism. 3. The multi-planar convex prism, wherein the first convex ridge surface is formed on the front side, and the back side is a flat surface perpendicular to the optical axis; 2. The second convex ridge surface prism having a convex ridge surface formed on the front side and a rear surface formed as a plane perpendicular to the optical axis, wherein the second convex ridge surface prisms are integrated with the back sides of the prisms. Polyhedral convex prism. 4. The method according to claim 3, wherein the first convex ridge prism and the second convex ridge prism have the same shape, and the outgoing light is substantially converged on the optical axis in a square shape. Polyhedral convex prism as described .