KR101367499B1 - Lithography system and projection method - Google Patents

Abstract

The present invention provides an electronic image pattern to an exposure mechanism for projecting an image onto a target surface, the exposure mechanism including a control unit for controlling exposure projection, the control unit of the exposure mechanism The control unit is provided at least partially within the projection space, while control data is provided by an optical signal, the optical signal comprising a free space optical connector comprising a modulated light beam that is emitted to the photosensitive portion of the control unit. Wherein the modulated light beam is coupled to the photosensitive portion using a mirrored apertured for incident axially the light beam on the photosensitive portion, wherein one of the mirrors The plurality of holes relate to a lithography system provided for the passage of the exposure projection.

Description

Lithography System and Projection Method {LITHOGRAPHY SYSTEM AND PROJECTION METHOD}

The present invention relates to a lithography system for projecting an image pattern onto a target surface, such as a wafer, using a free space interconnect by connecting control data by an optical signal to a control unit that controls exposure projection. In particular, it relates to a system in which the control unit is in close proximity to or within the projection space, and more particularly to a multi-beam-mask-less lithography system. In particular, the present invention relates to everything, such as light projection based on charged particles and lithography systems.

Such a system is known from the specific embodiment provided in International Patent Publication No. WO2004038509 in the name of the applicant, ie in FIG. 14 of this patent publication. Known systems include computer systems for providing pattern data of an image to be projected by so-called beam columns for introducing charged particles, in particular electrons, onto target surfaces such as wafers and inspection instruments. The beam column comprises a vacuum chamber that receives one or more charged particle sources and radiates particles in a manner known per se, in particular using an electric field to withdraw particles from the source (s).

In addition, the beam column focuses the radiation bundles of charged particles, divides the radiation bundles of charged particles into a plurality of charged particle beams (also called writing beams), and forms charged particle optics for forming exposure projections. It includes. The control unit for controlling the exposure projection is included in the form of charged particle optical means for shaping or guiding a recording beam, which is disclosed in the patent document by a blanker optic or modulator array comprising a blanking deflector and a blank by the blanking deflector. A record deflector array is provided for deflecting a record beam to perform an intended recording of a pattern using unrecorded beams.

For example, the blanker optics, originally known from International Patent Publication No. WO2004107050 in the name of the applicant, depend on computer-provided signals so that any part of a given recording beam is provided with an opening provided for each recording beam in a stopping plate. With a slope of a size that does not pass effectively, the recording beam deflects off a straight line trajectory parallel to the other recording beams, thereby achieving an "off" state of the particular recording beam.

All optics in the beam column are shaped using an array of openings, with the openings of the separate optics aligned to each other so that the recording beam in the column can pass through the target surface in a controlled manner. The known maskless multi-beam system is also provided with a blanking deflector having a source and a target surface disposed in its conjugate plane, ie it can be easily combined with the invention of WO2004 / 0819010. In this way the lithography system conveniently realizes the optical brightness of the source on the target surface. Also, in this way a minimum amount of space is required for the blanker array.

The target surface for the recording beam is held on a stage included in the beam column. The stage guided by the electronic control unit of the system moves with the surface perpendicular to the radiated recording bundle, preferably only in a direction transverse to the direction in which the recording bundle is finally deflected for recording purposes. Thus, the recording of the pattern by a known lithography system is based on the relative motion of the target surface and the blanker optics when transmitting a signal by the pattern streamer of the control unit, more specifically the so-called control unit. By regular "on off" switching of the recording beam.

Signal transmission for on / off switching, ie modulation of the recording beam, is carried out in the related known system by using light optics. In addition, the blanker optics comprise a photosensitive portion, such as a photodiode, for example for receiving an optical signal which is converted into an electronic signal by applying a method such as provided by the international patent publication WO2005010618 in the applicant's name. The optical signal is generated by switching from electron to light by the control unit for the system and transmitted to the beam column by an optical carrier (such as a glass fiber bundle that finally projects from a "transparent portion of the vacuum boundary"). The optical signal is projected onto the blanker optics using a lens system which is disclosed in the known system as consisting of a converging lens located between the photosensitive and transmitter portions of the deflector included in the blanker optics. The configuration of such a deflector, a photosensitive part and a photoelectric conversion part is made using both a so-called MEMS technique and a (Bi-) CMOS technique. In order not to use the reflectors, the light beams transmitted from the relevant known systems project far above the blanking optics in order to make the angle of incidence of the pattern information transmitting optical signal to the photosensitive element as small as possible. However, the above-mentioned patent publication containing such a prior art teaches that for other projection positions, a large angle of incidence that occurs at most of such alternative positions can be realized by using a mirror.

Although the general configuration of the lithographic system described above has proved satisfactory, it is known that in such oblique illumination systems, the transfer of unoptimized light is at least not as expected, while the aberrations are relatively large. . Thus, the present invention attempts to improve the light optics system (LOS) of this lithography system, although generally known maskless multi-beams. It is also an object of the present invention to improve lithography systems by increasing the light transmission efficiency and / or by reducing the possibility of aberrations in the optical optics.

The present invention solves the problem faced by a lithography system using at least one aperture for changing the direction of the light beam, which is provided with one or more apertures for passing exposure, for example a recording projection of the lithography system portion, at least to a considerable extent. Eliminate the problem. In particular, the free space optical coupler of the system according to the invention comprises a perforated mirror, i. In order to achieve an axial incidence, ie an angle of incidence of the light beam at least substantially perpendicular to the photosensitive element, wherein the mirror provides at least one hole for passing through one or more of the recording beams. Doing.

According to another insight specifying the invention, which is provided alternatively, an electronic image pattern is transferred to an exposure mechanism for projecting an image onto a target surface, the exposure mechanism including a control unit for controlling the exposure projection, and A control unit is at least partly included in the projection space of the exposure mechanism and provided with control data by an optical signal, the optical signal comprising a modulated light beam emitted to the photosensitive section of the control unit. Is coupled to the control unit, and the modulated light beam is connected to the photosensitive section using a perforated mirror, otherwise represented as a perforated mirror, for incidence of the light beam on the photosensitive section on the axis. Lithography system is obtained.

Using the system according to the invention, the presence of aberration is minimized by leaving the projection of the optical signal on the axis without at least noticeably interfering, i.e., preventing the exposure projection of the exposure apparatus of the lithography system. With the solution claimed in the present invention, the present invention realizes a relatively simple idea of implementing a new, advanced, impossible but highly desirable method.

The various aspects and features described and illustrated herein are applicable independently, wherever possible. These independent aspects, in particular the aspects and features described in the appended dependent claims, may be the subject of a split patent application.

The invention will be further illustrated by the exemplary method in the following embodiment of the maskless lithography system according to the invention, shown in the accompanying drawings.

1 is a schematic diagram of a conventional lithography system that is the starting point of the present invention.

2 is a schematic diagram of an improved optical optical system for a known lithography system according to the first embodiment.

3 is a schematic diagram of a structural configuration for the optical optical system of FIG. 2 in a lithography system.

4 is a schematic diagram of an improved optical optical system for a known lithography system according to a second embodiment.

In the drawings, at least functionally corresponding structural configurations are referred to by the same reference numerals.

The invention will be further illustrated by the exemplary method in the following embodiment of the maskless lithography system according to the invention, shown in the accompanying drawings.

1 shows an overall side view of a conventional lithography system improved by the present invention, in which the means of modulation 2 of the optical carrier Fb embodied by an optical emitter, ie an optical fiber Fb. ), The light beam 8 is projected onto the modulator array 24 using the optical system represented by lens 54. A light beam 8 modulated from each optical fiber end is projected onto the photosensitive element, ie the photosensitive portion of the modulator of the modulator array 24. In particular, the ends of the fibers Fb are projected onto the modulator array. Each optical beam 8 has a portion of pattern data for controlling one or more modulators, and through its modulation a signal for conveying modulator array commands based on the pattern data to implement a desired image on the target surface. Form a system.

FIG. 1 also shows a beam generator 50 which produces a diverging charged particle beam 51 (in this embodiment an electron beam). Using an optical system 52, in particular an electro-optical system, this beam 51 is shaped into a parallel beam. Parallel beams 51 impinge on beam splitter 53, resulting in a plurality of substantially parallel recording beams 22 directed to modulation array 24, which is otherwise represented by a blanker array.

Using a modulator in a modulation array 24 that includes an electrostatic deflector element, the recording beam 27 is deflected away from the optical axis of the lithography system, and the recording beam 28 passes through the modulator unbiased.

Using a beam stop array 25, the deflected write beam 27 is blocked. The recording beam 28 passing through the blocking array 25 is deflected in the deflector array 56 in the first recording direction, and the cross section of each beamlet is reduced using the projection lens 55. During recording, the target surface 49 moves relative to the rest of the system in the second writing direction.

The lithography system also includes a control unit 60 including a data storage device 61, a reading unit 62 and a data converter 63, including a so-called pattern streamer. The control unit 60 is located away from the rest of the system, for example outside the interior of the clean room. When using the optical fiber Fb, the modulated light beam 8 with the pattern data is transmitted to the projector 54 which projects the ends of the fibers onto the modulation array 24.

2 shows an optical optical system of the improved lithography system according to the first embodiment. The system involves the use of a perforated mirror 104 that is applied to realize in-axis incidence of the light beam 8 on the photosensitive elements of the modulator array 24. The perforated mirror comprises one relatively large hole through which all blanking deflected recording beams 27 and all unbiased recording beams 28 can pass, or a plurality of for each deflected recording beam or unbiased recording beam. Two relatively small holes (105). According to a preferred embodiment, the mirror 104 comprises a substantially flat reflective surface that is included in the system at an angle of 45 degrees or less, thus maintaining the incidence of the light beam 8 on the modulator 24 in the axial direction. Minimal space is required for the optical optical system. With this minimum axial space requirement, the freedom of design is achieved to place the LOS above or below the modulator array 24, which is an extremely complex part fabricated using CMOS and MEMS techniques. Increase the degree of freedom of manufacture. By using the perforated mirror 104, the focusing lens 106, which is preferably implemented by a lens system that performs a focusing function, is arranged as close to the mirror as possible, at least as close to the mirror than the fiber end 2. . By arranging the focusing lens 106 in close proximity to the perforated mirror 104, it is convenient that the perforated mirror can be applied without excessive loss of optical signal intensity that could exist due to the presence of the aperture 105. Is realized.

The array of fiber ends 2 according to the invention is provided with a micro lens array 101, forming a virtual fiber array 103, in fact an array of spots of focal plane for the micro lens 101. In certain independent aspects of the present invention, the microlenses of the microlens array 101 according to the preferred embodiment perform a magnification function of the optical signal transmitted by the specific fibers of the fiber array Fb. Thus, the lens system according to the present invention proposes a dual image system in which each signal is magnified by a micro lens, and then focused by the lens 106. Preferably in this way, independence is obtained in the setting for increasing the size of the effective spot of each fiber and the setting for decreasing the fiber pitch.

Regarding the first effect described above, according to the present invention, it is desirable to cover the widest possible area of the photosensitive element, which eliminates the need to focus the light signal 8 strongly, thereby reducing the chance of occurrence of aberrations. To reduce the need for other optical elements that increase the transmission of light, ie reduce the loss of light. The desired generated light spot is not much larger than the photosensitive area to minimize the loss of light due to projecting light onto the surrounding inert portion. However, this configuration is relatively sensitive to the positioning error of the light beam 8 in that a small displacement of the light beam implies a reduction in the amount of light received by the relevant photosensitive element (eg photodiode). Imply that. Thus, by making the size of the incident spot 24i larger (but not much larger than the photosensitive region), in accordance with the present invention, costly or complicated optical elements are not required in the free space connector of the LOS, while The sensitivity to misalignment of the incident light beam portion is moderately reduced. In this regard, misalignment may be due to the actual state of the litho system, structural inaccuracies, or a combination thereof. With regard to the second effect described above, unless excessive and consequently uneconomical manufacturing efforts are made, the pitch of the ends of the fibers Fb is inconsistent with the pitch of the photosensitive elements on the modulator array 24 and is specifically greater. . In the dual lens and dual imaging system of the present invention, independence in setting both parameters is obtained in a convenient manner.

FIG. 3 shows a configuration in which the lithographic system according to the invention preferably comprises the optical optical system described in accordance with FIG. 2. A holder 24S for the blanker or modulator array 24 is shown, by which the modulator array 24 is positioned within a charged particle column. The charged particle column is included in the housing Hv along with a holder for holding a wafer or other kind of target surface, thereby realizing vacuum conditions for the column and the target stage. The array of fibers Fb is fed through an opening in the degradable portion of the housing Hv, which is achieved by using a significant amount of vacuum friendly sealing material to realize air compression sealing of the fibers in the opening. In addition, the inner housing side end portion Fbv of the fiber is protected to a considerable extent from external mechanical shocks which may act on it. In addition, the end Fbv of the fiber array is mechanically fixed at its end 2 to the housing HI for the lens and mirror portions of the optical optical system. The housing HI is then fixed to the modulator array holder 24S. In this way, it is ensured in a convenient and mechanical way to fix the position of the fiber end 2 and the modulator array, in particular the photosensitive region, relative to each other. The array holder 24S is then connected to a collimator 52, a splitter 53, and an unshown frame for the elements that make up the charged particle column as discussed further in connection with FIG. 1.

As shown by lines in FIG. 3, the perforated mirror 104 covers the entire area of the modulator array, while the lens 106 covers the entire area of the oblique mirror 104 in the same manner. The lens 106 is embedded in the axial direction in proximity to the holder 24S.

It will be apparent from the foregoing description that the principle of the dual lens system, the mechanical fixing of the lens housing HI to the blanker 24 and the specific application of the perforated mirror 104 can all be applied independently of one another. In addition to this, the principle of dual imaging can be applied using off-axis projection instead of the preferred vertical projection of the present invention.

4 shows an optical optical system of an improved lithography system according to a second embodiment. This involves the use of a perforated mirror 107 which is applied to realize in-axis incidence of the light beam 8 on the photosensitive element of the modulator array 24. The perforated mirror comprises one relatively large hole 108 through which all of the blanking deflected recording beams 27 and all unbiased recording beams 28 can pass, or a deflected recording beam or an unbiased recording beam It includes a plurality of comparative small holes, one for each. According to a preferred embodiment, the mirror 104 comprises a focusing reflective surface, which is in particular at an angle for reflecting the incident light beam 8 towards the modulator 24, which reflecting surface in particular It becomes a concave surface to focus incident light beams 8 on the modulator 24 simultaneously.

Using a mirrored aperture with the focusing reflective surface 107, the focusing lens 106 can be omitted. Advantageously, it is realized that any loss of optical signal intensity, especially due to reflection on the surface of the focusing lens 106, may be reduced.

Further, the concave reflective surface of the focusing element, in particular the perforated mirror 107, in the second embodiment may be much closer to the modulator array 24 than the lens 106 in the first embodiment. Due to this close distance, the optical optical system of the second embodiment can be configured to have a larger number of holes and thus increased resolving power of the optical optical system.

In addition, in the second embodiment of FIG. 4, the array of fiber ends 2 is provided with a micro lens array 101 such that the virtual fiber array 103, in fact an array of spots in the focal plane for the micro lens 101. To form. The microlenses of the microlens array 101 perform an enlargement function of the optical signal transmitted by the specific fibers of the fiber array Fb. Thus, the concave reflective surface of the perforated mirror 107 according to the second embodiment enlarges each signal by a microlens, which is common to all the emitted optical signals, and then of the perforated mirror 107. A dual image system is proposed that focuses signals by the concave reflective surface.

Also, a perforated mirror having a focusing reflective surface 107 as shown in FIG. 4 can be combined with a focusing lens 106 as shown in FIG. In this case, the focusing elements 106, 107 comprise two optics, both of which may contribute to the focusing effect and / or may be used to reduce optical aberrations.

Apart from the concepts as described above and all relevant details, the present invention is also capable of direct derivation by those skilled in the art directly from all the features as defined in the following set of claims as well as the above features related to the invention. It's all about details. In the following set of claims, rather than fixing the meaning of the preceding terms, they are included only as representative meanings of the preceding terms, since any reference numerals corresponding to structures in the figures are supported when interpreting the claims.

Claims (16)

A lithographic apparatus in which an electronic image pattern is transferred to an exposure mechanism for projecting an image onto a target surface, The exposure mechanism is: A control unit 60 and a modulator 24 for controlling exposure projection, wherein the modulator is at least partially included in the projection space of the exposure apparatus and includes a photosensitive portion, wherein the control unit is controlled by an emitter portion. A control unit and a modulator, configured to provide control data to the modulator by a modulated light beam emitted to the photosensitive portion of the modulator; And A free space optical connector arranged to couple the modulated light beam to the photosensitive portion of the modulator Wherein the free space optical connector comprises a perforated mirror having a reflective surface arranged to reflect the modulated light beam toward the photosensitive portion of a modulator for axially incident on the photosensitive portion, A hole or holes in the mirror are provided for the passage of the exposure projection. The lithographic apparatus of claim 1, wherein the emitter portion is integrated into the apparatus to emit the modulated light beam perpendicular to the direction of the exposure projection. The lithographic apparatus of claim 1, wherein the free space connector is disposed downstream of the modulator. The lithographic apparatus of claim 1, wherein the free space connector comprising the emitter portion and the perforated mirror is included in a housing mechanically coupled to a modulator. A lithographic apparatus according to claim 1, wherein a focusing lens is integrated into said free space optical connector in the vicinity of said perforated mirror. A lithographic apparatus in which an electron image pattern is transferred by light projection to an exposure mechanism formed by a recording mechanism using a multi-beam exposure projection apparatus for maskless projection of a pattern on an exposure surface, A vacuum housing in which the recording mechanism is integrated; A multi-beam projection source configured to generate a plurality of recording beams for recording the pattern, the recording beam directed to a blanker array, the blanker array determining whether the beam should be deflected to the beam blocker A multi-beam projection source comprising a modulator unit having individual deflectors for individually deflecting recording beams in accordance with the information; And A light optic device including a light transmitting unit configured to transmit a pattern information signal to the modulator unit Wherein the modulator unit comprises a photosensitive element receiving a modulated light beam, the photosensitive element being received in the vicinity of the deflector, The opto-optical device comprises a free-space optical connector, the free-space optical connector forms an optical optical data carrier device configured to deliver a modulated light beam having pattern data towards the modulator unit, The free space optical connector comprises an emitter portion configured to emit a modulated light beam having the pattern data for the free space connector to the photosensitive element, The free space optical connector comprises a perforated mirror integrated into the projection trajectory of the plurality of recording beams, The mirror is disposed relative to the emitter portion and the photosensitive element to reflect a modulated light beam from the emitter portion for axial incidence onto the photosensitive element, And said mirror is provided with at least one hole for passing one or more recording beams. As a lithographic apparatus, By projecting the modulated data transmission light beam 8 to a recording device of a lithographic apparatus, an electronic image pattern is transferred to the recording device, which is then used to freely transfer the image pattern to the recording device. Including, The free space optical connector comprises a perforated mirror having one or more apertures, the mirror contained within the recording mechanism, arranged to reflect the modulated light beam for data transmission along the projection direction of the recording mechanism And passing the projection of the recording mechanism through the hole (s). delete delete delete delete delete delete delete delete delete

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