KR20100125047A - Optical device - Google Patents

Abstract

PURPOSE: An optical device is provided to adjust an interference pattern as desired by freely controlling an incident angle. CONSTITUTION: An optical splitter(116) partitions the light. A plurality of first adjustment mirrors(107,108) varies the route of the partitioned light. The plurality of first adjustment mirrors is rotatable. A plurality of second adjustment mirrors(109,110) changes again the route of the changed light. The plurality of second adjustment mirrors is movable on the curved guide.

Description

Optical device {OPTICAL DEVICE}

The present invention relates to a light splitter, and the angle of incidence can be freely adjusted, so that the interference pattern can be adjusted as desired, and the specific angle of incidence can be achieved by relatively easy operation without strictly adjusting the path axis of the light magnifier and the interference light. Due to its precise implementation, it relates to an optical device which has a small error and does not need a tilt device to correct the error.

In general, interference lithography is a process technology used to fabricate periodic patterns in semiconductor processing and related fields. An interference lithography technique is used to generate an interference signal using a coherence light source such as a laser. It is a process technique used to create an interference fringe and irradiate this signal onto a substrate coated with a photoresist to produce a pattern such as an intensity distribution of an interference signal.

An interference lithography system that implements this process technology has been used three to four optical devices to date, the most common of which is the Lloyd type interference lithography device, and the improved interference lithography device. 1 and 2 are shown for more detailed description. 1 is a schematic diagram illustrating the principle of an Lloyd type interference lithography apparatus, and FIG. 2 is a schematic diagram of an interference lithography apparatus which has been improved.

As shown in FIG. 1, the interference lithography apparatus 10 is an initially developed device, which has been widely used to date due to its simple device configuration and reliability. The light such as the laser oscillated by the optical oscillator 11 passes through the condensing lens 12 and the pinhole 13 and proceeds in the form of a spherical wave. The photocuring agent 16 is apply | coated on the board | substrate 14, and the reference mirror 17 is provided. After passing through the pinhole 13, a part of the light traveling in the spherical wave is incident on the reference mirror 17, and part of the light is incident on the substrate 14.

At this time, the part incident to the reference mirror 17 is referred to as the reference light and the light incident on the substrate, and the reference light is incident on the reference mirror (P2), and then reflected to the substrate surface, and the interference light on the substrate surface. Manna P1 forms an interference signal, and the photocuring agent 16 is cured according to the light intensity distribution of the interference signal. The intensity of the interference signal formed on the substrate surface is determined by the optical path difference between the reference light and the interference light. The light intensity at the point P1 of FIG. 1 is reflected at the point P2 of the reference mirror and is reflected to P1. The distance difference between the incident reference light and the interference light incident from the pinhole to the P1 point is determined. When the light intensity is shown on the entire surface of the substrate, it has a sinusoidal shape.

FIG. 2 is an optical system configuration diagram which is most widely used in a form that compensates for the disadvantages of the Lloyd type interference lithography apparatus of FIG. 1. In the interference lithography apparatus 20, light such as a laser oscillated by the optical oscillator 21 is separated into two beams via a mirror 22 and a beam splitter 23. These are referred to as left and right lights, respectively, and the left and right lights are each coated with a photocuring agent 27 through a beam expander composed of a mirror 24, a condenser lens 25, and a pinhole 26. (28) is investigated. The light expander is equally applied to the left and right lights, and enlarges the laser light to a size corresponding to the exposure area. FIG. 2 shows an example of enlarging light in the form of a spherical wave. In addition, an additional lens may be installed after the pinhole to enlarge the light in a parallel wave form.

The light intensity of the interference signal formed on the substrate 28 in the interference lithography apparatus 20 is determined by the distance difference from the pinholes 26 of the left and right optical magnifiers to the corresponding points, for example, at the point P1 of FIG. 2. The light intensity of is determined by the difference between the distance from the pinhole of the left light expander to P1 and the distance from the pinhole of the right light expander to P1. When the light intensity is shown on the entire surface of the substrate, it is generated in the form of sinusoidal wave.

FIG. 3 shows the geometric relationship and the light intensity distribution of an interference signal when two interference lights separated from a light source are combined on a substrate to form an interference signal in the interference lithography apparatus of FIGS. 1 and 2 described above. The two light sources causing interference are referred to as the left interference light 29 and the right interference light 30, and are formed at the angle of θ based on the vertical line 31 (z-axis direction) on the substrate 28 to which the photocuring agent 27 is applied. I think I investigate. At this time, the photocuring agent is generally applied on the substrate with a thickness of several micrometers to several hundred nm. Since the thickness is so thin, the photocuring agent is applied along the light intensity distribution of the interference signal on the surface, ignoring the change of the interference signal inside the photocuring agent. Exposed. The intensity distribution of the interference signal is shown. It takes the form of a cosine (or sine) function along the x-axis, and the period of the intensity distribution is as follows.

In Equation 1, λ is a center wavelength of the light source, and θ means an incident angle of left and right interference light shown in FIG. 3. After the light from the light source is separated into two or more lights, an interference signal using a path difference is generated on the substrate on which the photocuring agent is applied, and the method of patterning the photocuring agent using the same is the same. The cycle follows (Equation 1).

The interference lithography apparatus of FIG. 2 is more widely used than the Lloyd interference lithography apparatus of FIG. 1, which can freely adjust the exposure area and minimize the light intensity difference between two light sources that cause interference, thereby providing more visibility than the Lloyd type optical system. This is because there is an advantage that can generate a distinct interference signal. This reduces the exposure time in the patterning process and enables accurate pattern production.

One of the important improvements in the interference lithography apparatus of FIG. 2 is to freely adjust the pitch of the interference signal light distribution curve shown in FIG. 3 to produce patterns of various periods. As described above, the period of the light distribution curve follows Equation 1, and when considering this equation, in order to change the period of the pattern, it is necessary to change the wavelength of the light source or adjust the incident angle of the interference light.

In interference lithography, lasers with high coherence are often used as light sources. Currently, the wavelength of commercialized lasers is limited to about 3 to 4 lasers, and a laser having a wavelength that can cure the photocuring agent applied on the substrate must be used. However, it is not possible to adjust the period of the light distribution curve through this.

Secondly, adjusting the angle of incidence θ of the two interfering light is to change the position of the optical device, but it is not easy to freely manufacture the pattern of the desired period by easily adjusting it in the interference lithography apparatus of FIG. 2.

4 is a schematic diagram illustrating a method of adjusting an incident angle θ in the interference lithography apparatus of FIG. 2. For convenience of explanation, the optical device which splits into a laser and two interference light was abbreviate | omitted. As shown in FIG. 4, in order to change the angle of incidence, the positions of the left light magnifiers 37 and 38 and the right light magnifiers 39 and 40 must be moved, and a virtual concentric circle centered on the center of the substrate 28 is provided. It should move along the rotation. By comparing the positions 37 and 40 of the left and right optical magnifiers when the incident angle is θ ₁ and the positions 38 and 39 when changing to θ ₂ , the method of adjusting the position of the optical magnifier for adjusting the incident angle can be known. . When using this method, at least two mirrors (32-34, 33-40) must be used in each light magnifier to accurately enter the incident light incident from the fixed position into the condenser lens and the pinhole device of each light magnifier. do.

As can be seen in FIG. 4, each time the position of the light magnifier is changed, each mirror is precisely rotated so that the interference light passes through the mirror 34 and the condenser lens 35 of each light magnifier, and then the pinhole 36. Should be adjusted to focus). Although the distance from the substrate surface to the optical magnifier varies depending on the exposure area, it is generally 1 m or more away, and even if the optical magnifier is mounted on a circular guide centered on the substrate surface and the incident angle θ is adjusted, A position error of μm occurs.

In addition, the hole size of the pinhole depends on the quality of the interference light irradiated on the substrate, but uses a size of approximately several μm. Therefore, by adjusting only the rotation of the mirrors 32-34, 33-40, it is impossible to pass the interference light accurately through the pinhole 36, and an additional parallel shift device is needed to adjust the position of the mirror on the xz plane. Done. Moreover, due to the mechanical error of the guide, there is also a need for a tilt adjustment device to compensate for errors outside the xz plane, for example rotational errors about the x axis. As a result, at least one of the two mirrors for controlling the direction of the interference light must be equipped with a mechanical device capable of controlling the degree of freedom (excluding the condensing lens and the pinhole optical axis direction).

In view of this, the interference lithography apparatus of FIG. 2 must strictly adjust the path axis of the light magnifier and the interference light whenever the angle of incidence is adjusted, which means that it is difficult to control the interference lithography apparatus at a specific angle of incidence. Moreover, if the angle of incidence cannot be accurately controlled, the angle of incidence of the left / right interference light cannot be matched, which means that the period of the pattern to be made cannot be accurately controlled.

Accordingly, an object of the present invention is to provide an optical device capable of freely adjusting the angle of incidence and adjusting an interference pattern as desired.

In addition, an object of the present invention is to provide an optical device that can realize a specific angle of incidence by operating relatively easily without strictly adjusting the path axis of the light magnifier and the interference light.

In addition, due to the accurate implementation of the angle of incidence, it is an object of the present invention to provide an efficient optical device with less error and no tilting device for correcting the error.

According to a preferred embodiment of the present invention for achieving the above object of the present invention, the optical device of the present invention, in the optical device for projecting light to the object, the optical splitter for dividing the light, changing the path of the divided light And a plurality of rotatable first adjusting mirrors, and a plurality of second adjusting mirrors which redirect the light paths changed by the first adjusting mirrors, and which are movable on a curved guide and having the same focus. One of the adjustment mirrors is characterized by being located on a central axis line on the guide of the curve.

식을 만족하는 것을 특징으로 하며, 여기서, B는 상기 곡선의 가이드 상의 중심축 선상에 위치한 제1 조절미러의 회전 중심점에 서 상기 곡선의 가이드까지의 직선거리, C는 상기 대상물과 상기 곡선의 가이드까지의 직선거리, f는 상기 제2 조절미러의 초점거리이다.The optical device

The formula satisfies the formula, wherein B is a straight line distance from the center of rotation of the first adjustment mirror located on the center axis line on the guide of the curve, the guide of the curve, C is the guide of the object and the curve The linear distance to, f is the focal length of the second adjustment mirror.

The curved guide is a circle or a part of a circle, and at least one of the first adjustment mirrors is capable of translational movement. And a condenser lens disposed prior to the optical path of the optical splitter and condensing light, wherein the object is a substrate, and the optical device is preferably applied to cause optical interference on the substrate.

식을 만족하는 것을 특징으로 한다.In addition, in the optical device according to the present invention, in the optical device that causes interference light on the substrate, a plurality of first adjustment mirrors, each of which a plurality of light is incident to change the path, and by the first adjustment mirror And redirecting the altered path of light, the second adjusting mirror being movable on a circular guide and having the same focus, wherein one of the first adjusting mirrors is located on a central axis line on the curved guide, and the optical device Is

It is characterized by satisfying the equation.

Preferably, at least one of the first adjustment mirrors is capable of translational movement, and the plurality of lights are condensed by a condenser lens and then divided by a light splitter.

As described above, according to the present invention, the angle of incidence can be freely adjusted, so that the interference pattern can be adjusted as desired.

In addition, even if the path axis of the light magnifier and the interference light are not strictly controlled, there is an effect that a specific incident angle can be realized by relatively easy manipulation.

In addition, due to the accurate implementation of the angle of incidence, the error is small, there is an effect that does not need a tilt device for correcting the error.

Hereinafter, a preferred vertical disposal embodiment of the present invention will be described in detail with reference to the accompanying drawings, but the present invention is not limited or limited by the embodiment, and various applications, such as horizontal disposal, are possible.

5 is a perspective view of the main parts of the optical apparatus 100 according to the present invention. The present optical device can be applied to various devices including the interference lithography device.

As shown in the drawing, light 101 such as a laser oscillated by an optical oscillator not shown is reflected by the first mirror 102 in a 90 ° direction. In this case, the light may use the laser light itself from the laser source, or laser light amplified to a constant diameter by passing through a collimator to uniformly adjust the light intensity of the incident light.

After the light 101 passes through the condenser lens 103, the light 101 is divided into left and right lights 104 and 105 by the light splitter 116. At this time, the left light 104 uses the second mirror 106 to bend the light path in the 90 ° direction. The difference from the conventional structure in this optical device is that the incident light must be diverged through the light splitter 116 after passing through the condenser lens 103. Configuration is possible. Alternatively, the same result can be obtained by installing two identical condensing lenses after the splitter. That is, the position of the condenser lens may be installed before or after the light splitter. If the light condenser is installed before the light splitter, one condenser lens may be installed. Can be installed. In general, it may be advantageous to install one condenser lens before the light splitter. The condenser lens serves to spread the light over a predetermined area on the substrate after the incident laser light passes through a series of optical components. When the light passes through the condenser lens 103, the light converges at the focal point of the lens. Although slightly different from the parallel beam path when passing through the light splitter of 2, such path difference is negligible because the interference lithography apparatus uses a condenser lens having a focal length of several tens of mm or more.

The left and right lights 104 and 105 change light paths through the first left and right adjustment mirrors 107 and 108, respectively, and are incident and reflected on the second left and right adjustment mirrors 109 and 110 located at the upper side thereof. It forms an interference pattern.

The second left and right adjustment mirrors 109 and 110 serve to collect left and right interference light on the substrate 120 at all times even when the light paths are changed using the first left and right adjustment mirrors 107 and 108. The second left and right adjustment mirrors 109 and 110 may include driving wheels 112 and 113, respectively, to move on the circular mirror guide 111. At this time, the center of each of the second left and right adjustment mirrors (109, 110) is adjusted and installed so as to match the space.

Since the second left and right adjustment mirrors 109 and 110 can travel on the circular mirror guide 111, the angle of incidence can be easily adjusted at various angles, and each mirror 109 and 110 is preferably fixed in place. One, it may be configured to allow a rotational movement around the fixed shaft (114, 115). In addition, the rotation of the center of the fixed shaft (114, 115), or the traveling on the circular mirror guide 111 can be used to easily adjust the incident angle by attaching an automated device. In addition, in the present exemplary embodiment, two second left and right adjustment mirrors 109 and 110 are illustrated, but three or more mirrors may be installed on the circular mirror guide 111.

In this case, the center of the circular mirror guide 111 is designed to coincide with the center of the second left and right adjustment mirrors 109 and 110, so that the second left and right adjustment mirrors 109 and 110 are positioned at a position on the circular mirror guide 111. Even if so, the light path is adjusted automatically. The circular mirror guide 111 may be circular or elliptical.

6 is shown for more detailed description.

6 is a conceptual diagram illustrating the principle of an interference lithography apparatus according to the present invention. Here, the portion shown by the solid line shows the optical path and the optical component (eg, the second left and right adjustment mirror) at an arbitrary position (eg, when the incident angle is θ ₁ ), and is shown by the dotted line. The part shows the optical path and the optical component at different positions (for example, when the incident angle is θ ₂ ).

As shown in FIG. 6, the first right adjustment mirror 108 is designed to rotate about the point B, and is located on the optical axis of the circular mirror. At this time, the relationship between B and the point C corresponding to the optical axis on the substrate 120 is represented by the following equation (2).

In Equation (2), B denotes the distance from point B to point A on the optical axis on the circular mirror, C denotes the distance from point C to A on the substrate, and f denotes the focal length of the circular mirror. The value corresponds to half of the radius of the mirror guide 111. This apparatus satisfies (Equation 2).

If the first right adjustment mirror 108 is rotated to change the traveling direction of the light, it passes through the C point on the substrate after being reflected by the second left and right adjustment mirrors that move the circular mirror guide 111. Therefore, the incident angle of the right interference light can be freely adjusted only by the rotational movement of the mirror.

In the case of the first left adjustment mirror 107, the same as the first right adjustment mirror 108 should be rotated about the point B, which is difficult to implement mechanically, the first right adjustment as in FIG. It is installed next to the same plane as the mirror 108. At this time, when the first left adjustment mirror is rotated to adjust the light direction, the starting point of the light traveling direction on the optical axis is changed, which means that the B and C distances are changed in Equation (2).

Therefore, when the first left adjustment mirror 107 rotates, it is necessary to adjust the height of the adjustment mirror so that the light traveling direction is always located at the point B on the optical axis. In FIG. 6, the height is adjusted together with the rotation of the first left adjustment mirror 107 at the time of θ _{1 and} at the time of θ ₂ , thereby showing a state in which the position on the optical axis in the light traveling direction always coincides with the point B. FIG. In this case, since the interference light by the left adjustment mirror satisfies (Equation 2), the incident angle can be freely adjusted similarly to the right interference light.

6 is only one embodiment, and any change of the invention including the present technical concept is possible, and for example, modifications such as changing the configuration of left and right, using both rotational and translational movements of left and right are possible. And it will be clear that it is included in all the scope of the present invention.

As described above, although described with reference to the preferred embodiment of the present invention, those skilled in the art various modifications and variations of the present invention without departing from the spirit and scope of the invention described in the claims below I can understand that you can.

1 is a schematic diagram for explaining the principle of an Lloyd type interference lithography apparatus.

FIG. 2 is an optical system configuration diagram which is most widely used in a form that compensates for the disadvantages of the Lloyd type interference lithography apparatus of FIG. 1.

FIG. 3 is a diagram illustrating a geometric relationship and light intensity distribution of an interference signal when two interference lights separated from a light source are combined on a substrate to form an interference signal in the above-described interference lithography apparatus of FIGS. 1 and 2.

4 is a schematic diagram illustrating a method of adjusting an incident angle θ in the interference lithography apparatus of FIG. 2.

5 is a perspective view of the main parts of the optical apparatus 100 according to the present invention.

6 is a conceptual diagram illustrating the principle of an interference lithography apparatus according to the present invention.

<Description of the symbols for the main parts of the drawings>

100: optical device 101: optical

102: first mirror 103: condenser lens

104: left light 105: right light

106: second mirror 107, 108: first left and right adjustment mirror

109 and 110: second left and right adjustment mirrors 114 and 115: fixed shaft

116: light splitter 120: substrate

Claims (10)

An optical device for projecting light onto an object, A light splitter for splitting light; A plurality of first adjustment mirrors that change a path of the divided light and are rotatable; And A plurality of second adjustment mirrors which redirect the light path changed by the first adjustment mirror and which are movable on a curved guide and have the same focus; And wherein one of the first adjustment mirrors is located on a central axis line on the guide of the curve. The method of claim 1, The optical device

Optical device, characterized in that to satisfy the equation. (Where B is a straight line distance from the center of rotation of the first adjustment mirror located on the center axis line on the guide of the curve to the guide of the curve, C is a straight line distance from the object to the guide of the curve, f is the first) 2 The focal length of the adjustment mirror.) The method of claim 1, The curved guide is circular or part of a circle. The method of claim 1, At least one of the first adjustment mirror is an optical device, characterized in that for translation. The method of claim 1 And a condenser lens disposed before the optical path of the optical splitter and condensing light. The method of claim 1 And said object is a substrate, said optical device causing optical interference on said substrate. In an optical device that causes interference light on a substrate, A plurality of first adjustment mirrors each of which receives a plurality of lights to change a path; And A plurality of second adjustment mirrors which change the path of the light changed by the first adjustment mirror and are movable on a circular guide and have the same focus; Wherein one of the first adjustment mirrors is located on a central axis line on the guide of the curve, and the optics

Optical device, characterized in that to satisfy the equation. (Where B is a straight line distance from the center of rotation of the first adjustment mirror located on the center axis line on the circular guide to the circular guide, C is a straight line distance between the substrate and the circular guide, f is the 2 The focal length of the adjustment mirror.) The method of claim 7, wherein The curved guide is circular or part of a circle. The method of claim 7, wherein At least one of the first adjustment mirror is an optical device, characterized in that for translation. The method of claim 7, And the plurality of lights are divided by a light splitter after they are collected by the condenser lens.

Images