TW201510680A - Lithography system and projection method - Google Patents

Abstract

The inventions relates to a lithography system in which an electronic image pattern is delivered to a exposure tool for projecting an image to a target surface, said exposure tool comprising a control unit for controlling exposure projections, said control unit at least partly being included in the projection space of the said exposure tool, and being provided with control data by means of light signals, said light signals being coupled in to said control unit by using a free space optical interconnect comprising modulated light beams that are emitted to a light sensitive part of said control unit, wherein the modulated light beams are coupled in to said light sensitive part using a holed mirror for on axis incidence of said light beams on said light sensitive part, the hole or, alternatively, holes of said mirror being provided for passage of said exposure projections.

Description

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, wherein the control material is coupled to a control unit to control exposure projection with an optical signal, thus using a free space interconnect, the present invention In particular, it relates to a system in which the control unit is contained in the vicinity of the projection space or in the projection space, more particularly in connection with a multi-beam line reticle lithography system. In principle, the invention has the same relationship with charged particles and light projection based on lithography systems.

A system is known, for example, from the international patent publication WO2004038509, which is known from the particular embodiment provided in FIG. The known system includes a computer system that provides image pattern data that is projected by a so-called beamstring for projecting charged particles, particularly to project electrons onto target surfaces such as wafers and inspection tools. The beamstring column is comprised of a vacuum chamber in which one or more charged particle sources are contained, and the particles are emitted in a manner known per se, including the use of an electric field to extract particles from the one or more particle sources.

The beamstring column further includes charged particle optics to polymerize the emitted charged particle beam, separating the same charged particle beam into multiple charged particle rays, which are further referred to as writing rays, and then shaped into an exposure projection. A control unit for controlling the exposure projection, which forms or guides the writing radiation in a charged particle optics, is shown here A masking optic or modulation array comprising a masking deflector is included, and a write deflection array that deflects the writing rays such that the pattern written by the writing ray is not obscured by the obscuring deflector.

It is known from the art of obscuring optical components, which is known from the International Patent Publication No. WO2004107050, to deflect a writing ray away from a linear trajectory parallel to other writing rays in accordance with a signal provided by the computer to achieve a tilt amount. Any portion of the write ray is rendered ineffectively through the opening, wherein the opening is provided over the stop plate for each write ray, thus initiating an "off" state of the particular write ray.

All of the optical components in the beamstring are formed in an open array, aligned with the openings of the respective components such that the path of the written rays in the beamstring is directed toward the target surface in a controlled manner. Known reticle multi-radiation systems are typically further provided with a blanking deflector that covers both the ray source and the target surface, which are disposed in a conjugate plane therein, that is, can easily be combined with W02004/ The combination of the targets of 0819010. In this way, the lithography system smoothly achieves optimal brightness of the source on the target surface. And in this way it is only necessary to cover the minimum amount of space in the array.

The target surface to which the radiation is written is held on a platform that is contained in the beamstring. The platform is guided by the electronic control unit of the system and moves vertically with respect to the transmitted write beam line with the surface, preferably only in a direction transverse to the direction in which the write beam is deflected for the last write purpose. It is known that the write pattern of the lithography system is thus affected by the relative motion of the target surface and the timing of the "on" and "off" switching of the written rays, wherein the switching is signaled by the masking optics at the control unit It is carried out at the time, and more particularly by the so-called pattern light.

The signal used to switch on/off, that is, the modulation of the written rays, is performed using optical means in a related known system. The masking optics thus comprise a light-sensitive component, such as a photodiode, for receiving an optical signal and converting the optical signal into an electronic signal, that is, the measures provided by International Patent Publication No. WO2005010618. The optical signal is converted into light through the system control unit The signal, and when a bundle of glass fibers is finally projected from a transparent portion such as a vacuum boundary, the optical carrier is used to transport the light to the beamstring. A lens system is used to project an optical signal onto the obscuring optic. In known systems, the lens system is disclosed as containing a converging lens between the transmitting component and the light sensitive component of the deflector plate, the deflector being contained in the obscuration In optical components. The configuration of the deflection plates, the light-sensitive components, and the optical power conversion system are performed using so-called MEMS- and (Bi-) CMOS technologies. Thus avoiding the use of mirror components, in known related systems, the signal light rays are projected from a distance above the masking optics such that the pattern information carries the light signal to a minimum possible incidence on the light sensitive element. angle. However, the publication containing the related embodiments teaches that when a mirror is used to correct a large angle of incidence, projections at other locations can be achieved, with larger angles of incidence occurring at most such alternative locations.

While the general arrangement of the lithography system described above has proven to be satisfactory, some disadvantages can be noted in the disclosed tilted illumination system where it suffers from non-optimal light transmission, at least less than the desired value and in which It suffers from relatively large aberrations. The present invention therefore generally seeks improvements in known multi-beam lithography systems without masks, but in particular improvements in optical systems (LOS) therein. The present invention further has the object of improving the lithography system by increasing the light transmission efficiency therein and/or the opportunity to reduce the aberration of the optical component therein.

The present invention solves or at least largely eliminates the problems encountered in using a mirror to change the direction of the light ray in a lithography system, in which one or more holes are provided for exposure, that is, providing the lithography system. Write projection. Particularly in accordance with the invention, the free-space optical interconnect of such a system comprises a perforated mirror that is integrated in the projection trajectory of the plurality of writing rays, wherein the mirror is relative to the emitting component and The light sensitive element is configured to achieve a coaxial, ie at least substantially perpendicular, incidence of the light ray on the sensitive element, the mirror having at least one aperture allowing one or more of the write ray to pass.

In accordance with further observations based on the present invention, another option is to provide a lithography system that transmits an electronic image pattern to an exposure tool for projecting the image onto a target surface, the exposure tool including a control unit to control exposure projection, the control The unit is at least partially contained in a projection space of the exposure tool and is provided with control data via an optical signal means for coupling the optical signal to the control unit using a free-space optical interconnect, the interconnection being light-sensitive by the transmission to the control unit a modulated light ray composition of a component, wherein the modulated light ray is apertured, and the other is selected to be referred to as a apertured mirror to couple with the light sensitive component such that the light ray is coaxially incident on the light sensitive component, One or more apertures of the mirror provide access to the exposure projection.

Using a system in accordance with the present invention, the occurrence of aberrations is minimized by maintaining the optical signal on a coaxial projection, at least without significant interference, i.e., blocking the exposure projection of the lithography system exposure tool. The invention is implemented in a new, previously unpredictable manner using a solution to the patented scope, although in a relatively simple manner it is considered to be performed in a highly advantageous manner.

The various points and features that have been described and illustrated in the specification can be applied individually wherever possible.

2‧‧‧End of module tool

8‧‧‧Light rays

22‧‧‧Writing rays

24‧‧‧Transformation array

24i‧‧‧ light spots

24S‧‧‧ seats

25‧‧‧ Stop array

27‧‧‧Writing rays

28‧‧‧Writing rays

35‧‧‧Optical system

49‧‧‧ Target surface

50‧‧‧ray generator

51‧‧‧Powered particle beam

52‧‧‧Optical system

53‧‧‧ray beam splitter

54‧‧‧Projector

55‧‧‧Projection lens

56‧‧‧ deflection plate array

60‧‧‧Control unit

61‧‧‧Data storage

62‧‧‧Reading unit

63‧‧‧ Data Exchanger

101‧‧‧Microlens array

103‧‧‧Fiber Array

104‧‧‧ hole mirror

105‧‧‧ hole

106‧‧‧focus lens

107‧‧‧With a hole mirror

108‧‧‧ hole

Fb‧‧‧ fiber

Fbv‧‧‧ end parts

HI‧‧‧ lens housing

Hv‧‧‧ outer cover

The invention is further illustrated by way of example, and is illustrated by the embodiment of the reticle lithography system according to the invention shown in the drawings.

1 is a schematic diagram of a prior art lithography system; FIG. 2 is a schematic diagram of a modified optical system for use in a known lithography system according to the first embodiment; FIG. 3 is a schematic diagram of a structural configuration for lithography In the optical system of Figure 2 of the system; and Figure 4 is a schematic illustration of an improved optical system for use in a known lithography system in accordance with the second embodiment.

In each figure, the structural features are at least functionally corresponding features by the same component No.

Figure 1 represents an overall side view of a prior art lithography system modified by the present invention in which an optical system is used to project light rays 8 when the optical transmitter Fb is used to implement the light emitter or optical carrier Fb module tool end 2 On the modulation array 24, the optical system is represented by a lens 54. Each modulated light ray 8 from the end of the fiber optic is projected onto the light sensitive element, that is, the light sensitive component on the modulator of the modulated array 24. In particular, the end of the fiber Fb is projected onto the modulation array. Each of the light rays 8 carries a portion of the pattern data to control one or more modulators, wherein the modulation is a signal system to convert the pattern data based on the modulation array indication to achieve a desired surface on the target surface Image.

Figure 1 also shows a ray generator 50 which produces a divergent charged particle beam 51, in this example an electron beam. In an example of an electro-optical system, an ray 51 is shaped into a parallel ray using an optical system 52. The parallel rays 51 strike the beam splitter 53, producing a plurality of substantially parallel written rays 22 that are directed to another modulation array 24, which is selectively referred to as a blanking array.

A modulator is utilized in the modulation array 24, including an electrostatic deflection element that deflects the write beam 27 away from the optical axis of the lithography system, while the write beam 28 passes through the modulator undeflected.

The deflected write ray 27 is stopped using the ray stop array 25. The write rays 28 of the stop array 25 are deflected in the first writing direction in the deflection plate array 56, and the cross section of each beam is reduced using the projection lens 55. During writing, the target surface 49 moves in the second writing direction relative to the rest of the system.

The lithography system further comprises a control unit 60 comprising a data store 61, a readout unit 62 and a data exchanger 63 containing so-called pattern light. The control unit 60 is located at other distal portions of the system, such as outside of the clean room. Using fiber Fb, will have a map The modulated light ray 8 of the file is transmitted to the projector 54 to project the end of the fiber onto the modulation array 24.

Fig. 2 graphically represents an optical system for improving a lithography system according to the first embodiment. It is necessary to use a perforated mirror 104 which is applied to achieve coaxial incidence of the light rays 8 over the light sensitive elements of the modulation array 24. In addition, the apertured mirror contains relatively large apertures to cover all deflection write rays 27 and to pass all undeflected write rays 28 through the aperture, or to include a plurality of relatively small apertures 105, each for each aperture Each deflected or undeflected write ray. Depending on the preference, the mirror 104 includes a substantially flat reflective surface that is included in the system at an angle of 45 degrees, so that when the light ray 8 is maintained at normal incidence in the modulator 24, the optical system requires only an axial minimum space. the amount. This axial minimum amount of space requires design freedom to place the LOS on the upper or lower side of the modulation array 24, which in turn increases the manufacturing freedom of the array 24, which is very expensive when fabricated using CMOS and MEMS technology. The complex part. When using the apertured mirror 104, the focusing lens 106 is preferably implemented with a focusing function of the lens system, including at a position as close as possible to the apertured mirror, at least closer to the mirror than the fiber end 2. By placing the focusing lens 106 at the proximal end of the apertured mirror 104, the application of the apertured mirror can be achieved smoothly without excessive loss of optical signal strength, which would otherwise occur due to the presence of the aperture 105.

The fiber end array 2 is completed in accordance with the present invention in a microlens array 101 which forms a substantial fiber array 103, which is actually an array of spots on the focal plane of the microlens 101. In conjunction with a particular and independent aspect of the present invention, a microlens of microlens array 101 here performs an amplification function of the optical signal in accordance with an embodiment, acting in an optical signal transmitted by a particular optical fiber of fiber array Fb. The lens system according to the invention thus proposes a dual imaging system comprising amplifying each signal by a microlens tool and then focusing the signal through the lens 106, which is the same for all transmitted optical signals. In this way, the set independence is smoothly achieved with an increase in the effective spot size of each fiber, and the independence set under the condition of reducing the fiber pitch.

As for the first effect described above, it is preferred according to the invention to cover the light sensitive element as much as possible. The area, which eliminates the strong focus requirements of the optical signal 8, thus reducing the chance of aberrations and reducing the need for further optical components, which can enhance the transmission of light, i.e., reduce losses therein. The desired and generated spot is not much larger than the light sensitive area to minimize the loss of light projected around and inside. This configuration, however, implies that the projection of light is quite sensitive to the positional error of the light ray 8, with a small displacement suggesting that the amount of light reduced is greater than that received by the associated light sensitive element, that is, the photodiode. Thus, by making the size of the spot 24i larger than but not much larger than the light sensitive area, expensive or complex optical elements required in the free space interconnection of the LOS can be avoided according to the invention, while on the other hand the incident light rays are incident on the part The sensitivity of the bias can be reasonably reduced. From this point of view, the bias can be attributed to the actual situation of the lithography system, due to structural inaccuracies or a combination thereof. As for the second effect mentioned above, the pitch of the ends of the optical fibers Fb is incomparable with the pitch of the light sensitive elements on the modulation array 24, and in particular, much larger, otherwise insufficient manufacturing efforts will be required. With the current dual lens and dual image system, the independence of setting two parameters at the same time can be advantageously obtained.

Figure 3 represents a preferred optical system integration configuration in accordance with the present invention in Figure 2 in a lithography system. It shows a stand 24S for the above-described blanker or modulation array 24 via which the modulation array 24 can be placed on a charged particle column. Such charged particle columns are contained in the housing Hv together with a fixed wafer or other type of target surface mount, in such a way that the vacuum conditions required for the particle column and the target platform can be achieved. The fiber Fb array is fed from an opening of the removable portion of the housing Hv where a tight air seal of the fiber at the opening can be achieved by using a relatively large amount of vacuum compatible sealing material. The end piece Fbv of the fiber inside the housing is thus largely fixed by an external mechanical force acting on it. The end piece Fbv of the fiber array is further mechanically fixed at its end 2 to the lens of the optical system and to the outer cover HI used by the mirror member. The cover HI is then fixed to the modulation array holder 24S. In this way, the position of the fiber end 2 and the modulation array is fixed in an advantageous, mechanical manner, in particular the light-sensitive areas therein are fixed relative to one another. In turn, the array shelf 24S is connected to an undescribed One of the component frames, such as collimator 52, beam splitter 53, as discussed further below in Figure 1, constitutes a charged particle column.

Figure 3 shows, in one dimension, the apertured mirror 104 covers the area of the entire modulated array, while the same lens 106 covers the entire area of the tilted mirror 104. The lens 106 is thus axially integrated in the immediate vicinity of the mount 24S.

It will be apparent from the above that the principle of the dual lens system: mechanically fixing the lens housing HI to the shutter 2 and the specific application of the apertured mirror 104 can be applied independently of each other. The latter can further apply the dual imaging principle when using off-axis projection instead of the current preferred vertical projection.

Figure 4 graphically represents the optical system of the lithography system improved in accordance with the second embodiment. It requires the use of a perforated mirror 107 to effect coaxial incidence of the light ray 8 at the light sensitive elements of the modulation array 24. In addition, the apertured mirror includes a relatively large aperture 108 through which all deflected write rays 27 are obscured or all undeflected write rays 28 are passed through or contain a plurality of relatively small holes, each Holes are used for each deflected or undeflected write ray. Depending on the preference, the mirror 104 comprises a focused reflective surface, which is disposed at an angle, reflecting the incident light ray 8 towards the modulator 24, and the reflective surface, in particular a concave surface, for simultaneously illuminating the incident light ray 8 Focus on the modulator 24.

The focusing lens 106 can be omitted with a perforated mirror in cooperation with the focusing reflective surface 107. It can be more clearly understood that, in particular due to surface reflection of the focusing lens 106, any loss of optical signal intensity will be further reduced.

Moreover, it will be appreciated that the focusing elements of the second embodiment, particularly the concave reflecting surface of the apertured mirror 107, are closer to the modulation array 24 than the lens 106 of the first embodiment. Due to this closer distance, the optical system of this second embodiment can be designed with a larger numerical aperture and thus has greater optical system resolution.

In the second embodiment of FIG. 4, the array of fiber ends 2 is completed with the microlens array 101. Formed as a substantial fiber array 103, the end 2 is in fact an array of spots in the focal plane of the microlens 101. Through the optical fiber of the optical fiber array Fb, one microlens in the microlens array 101 performs an amplification function of optical signal transmission. The concave reflecting surface of the apertured mirror 107 according to the second embodiment thus sets a dual imaging system that includes the function of amplifying the respective signals by the microlenses for all of the emitted optical signals, and the concave through the apertured mirror 107. The function of the reflective surface to then focus the signal.

Furthermore, as shown in Figure 4, it will be appreciated that a perforated mirror having a focused reflective surface 107 can also be combined with a focusing lens 106 as shown in Figure 3. In this case the focusing elements 106, 107 comprise two optical components and both optical components can contribute to the focusing effect and/or can be used to further reduce the aberrations of the optical components.

In addition to the concepts as described above and all the accompanying details, the present invention also relates to all features defined in the scope of the claims, and all of the drawings that can be directly and explicitly described by those skilled in the art and related to the present invention. The details obtained. The scope of the patent application is not intended to limit the meaning of the foregoing terms, and any component symbol corresponding to the structure in the drawings is used to support the reading of the scope of the patent application, which merely serves as an illustrative purpose of the foregoing term.

2‧‧‧End of module tool

24‧‧‧Transformation array

24S‧‧‧ seats

60‧‧‧Control unit

101‧‧‧Microlens array

104‧‧‧ hole mirror

106‧‧‧focus lens

Fb‧‧‧ fiber

Fbv‧‧‧ end parts

HI‧‧‧ lens housing

Hv‧‧‧ outer cover

Claims (9)

A lithography system in which a plurality of write rays (22, 28) are used to transfer an electronic image pattern to an exposure tool to project an image onto a target surface (49), the exposure tool comprising a wire column for composing a charged particle beam a frame of components, the lithography system comprising: a target mount for holding a wafer or other kind of target surface; a vacuum envelope (Hv) for implementing the charged particle beam column and a vacuum condition of the target mount; a modulation array (24) provided with a modulator comprising an electrostatic deflector element for using a write beam (22) from an optical axis of the lithography system Deviating away or letting the undeflected writing radiation (28) pass through the modulator, the modulation array (24) being at least partially contained in a projection space of the exposure tool, the modulator being provided with control data For controlling the written ray by means of an optical signal comprising a modulated light ray (8), the modulated light ray (8) is emitted to the light sensitive component of the modulation array, the control data is transmitted through Provided by an optical interconnect carrying the optical signal, the optical interconnect package An optical fiber (Fb) array coupled to the exposure tool through the vacuum enclosure (Hv), wherein the optical signal is ultimately coupled to the modulation (24) array by using a free-space optical interconnect, wherein the lithography The system further includes a rack (24S) for the modulated array (24), wherein the mount (24S) is coupled to the frame, wherein the array of optical fibers (Fb) is traversed using a vacuum compatible sealing material An opening in the vacuum wall of the vacuum envelope (Hv), and wherein the fiber of the fiber (Fb) array has its end portion The member is then mechanically coupled to a free space optically coupled housing (H1) in one of the vacuum spaces of the charged particle beam column, and wherein the free space optical interconnect housing is secured to the frame for the modulated array seat. A lithography system according to claim 1 wherein a portion of the vacuum envelope (Hv) fed through the array of optical fibers (Fb) is detachable. A lithography system according to claim 1 or 2, wherein an inner vacuum cover end portion (Fbv) of the optical fiber (Fb) is fixed by external mechanical force. A lithography system according to claim 1 or 2, wherein the vacuum compatible sealing material achieves an air tight seal of the opening. A lithography system according to claim 1 or 2, wherein the free-space optical connection housing (H1) fixes the fiber end of the fiber (Fb) array with respect to the light sensitive area of the modulator (24) (2) )s position. A lithography system according to claim 1 or 2, wherein the free space optical connection housing (H1) covers a lens component (106) of the optical interconnection. A lithography system according to claim 1 or 2, wherein the free-space optical connection housing (H1) covers the light-sensitive component for coupling the light ray (8) to the modulation array (24) A mirror (104; 107) includes a hole (105; 108) for the passage of the writing ray (27, 28). A lithography system according to claim 1 or 2, wherein the free space interconnection is included at a downstream side of the control unit. A lithography system according to claim 1 or 2, wherein the free-space optical interconnect is comprised between a control unit and a stop plate, the control unit being formed by the modulation array (24) The write ray is masked and the stop plate is used to stop the write ray deflected by the modulation array.