KR20120035151A - Charged particle optical system comprising an electrostatic deflector - Google Patents

Abstract

The present invention relates to a charged particle optical system comprising an electrostatic deflector for deflecting a plurality of beamlets of charged particles, the electrostatic deflector comprising first and second electrodes, the electrodes at least partially freestanding. And the deflector deflects the plurality of beamlets by the action of an electric field between the electrodes, the plurality of beamlets pass between the electrodes, and the plurality of beamlets form a passing window. And the passage window extends in a first direction, wherein the plurality of beamlets are arranged in a single row extending in the first direction, the size of the passage window in a direction crossing the first direction is Matched to the diameter of the beamlet and the actual portion of the electrostatic deflector extends beyond the passage window in the first direction. The.

Description

Charged particle optical system with electrostatic deflector {CHARGED PARTICLE OPTICAL SYSTEM COMPRISING AN ELECTROSTATIC DEFLECTOR}

The present invention relates to a charged particle optical system comprising an electrostatic deflector for deflecting one or more beamlets of charged particles, the deflector comprising first and second electrodes, the beamlet passing between these electrodes. And the beamlet is deflected by setting the potential difference between the electrodes.

The present invention further relates to the use of such charged particle optical systems.

One such charged particle system is known from US 6,897,458. This system is a maskless lithography system. Along this lithography system, a beam of charged particles, such as electrons, is separated into a plurality of beamlets in the hole plate. This beamlet subsequently passes through a beamlet blanker array that is focused to the desired diameter and includes a blanking electrostatic deflector. Upon application of voltage to the blanking deflector, the beamlets are deflected and thus terminate in a beamlet stop array located behind the beamlet blanker array. Without deflection, this beamlet reaches a set of lenses to focus the beamlet over the target surface. Scanning deflection means move the beamlets together in one direction over the target surface.

Electrostatic deflectors can be used for blanking and scanning deflectors in such maskless lithography systems and in other high speed deflection applications. Typical examples are oscilloscope tubes, electron beam lithography systems and inspection systems and streak cameras. A common type of electrostatic deflector is a planar deflector, which includes two parallel plates with opposite voltages + V and -V. The electric field is here generated in the (x-) direction perpendicular to the plate. This planar deflector deflects the beam in only one direction. A disadvantage of the planar deflector is that the x and y deflections must be applied sequentially at different distances (ie different z-positions) to the target, for example a wafer of semiconductor material.

Another type of deflector is a multipole deflector, the most common of which is an octapole deflector consisting of curved plates with cylindrical or conical segments. By applying a suitable combination of electrode potentials to the plate, deflections in two orthogonal directions (x and y) can be applied simultaneously. The disadvantage of this deflector type is its complicated construction.

The prior art document US Pat. No. 6,897,458 specifies a planar specific electrostatic deflector for use as scanning deflection means. This deflector comprises electrodes arranged to deflect the assembly of the electron beamlets in a single direction. This electrode can be placed in the form of a strip on a suitable plate. Alternatively, this strip-shaped electrode can be placed on a set of projection lenses on the side facing the target surface, or alternatively can be placed on a separate plate between the set of lenses and the target surface.

10 shows a schematic cross sectional view of a portion of the prior art electrostatic deflector 11. This deflector 11 comprises a first strip 131, a second strip 132 and a third strip 133, which are above the substrate 150. Pass-through window 140, for example a through-hole, extends through substrate 150 between the strips 131, 132, 133. This lithography system is designed such that charged particles, ie beamlets of electrons, pass through the passage window 140. The first and third strips 131, 133 are part of the first electrode, and the second strip 132 forms part of the second electrode. Thus, the second strip 132 has a polarity opposite to that of the first and second strips 131, 133. In this example, the second strip 132 is a cathode. Upon application of the potential difference between the first and second electrodes, an electric field towards the second strip 132 is generated. Looking at the continuous rows of the electrode strips 131, 132, 133 of opposite polarity, the electric field generated between the first and second strips 131, 132 is generated by the electric field generated between the second and third strips 132, 133. Has the opposite direction. As a result, the beamlet 7 is deflected by the electric field in the opposite direction.

This bias shows a disadvantage; The surface area covered by the grid of the beamlets 7 is larger when the beamlets 7 are deflected than when they are not deflected. This difference in surface area causes problems in writing the pattern onto the target surface which is much larger than the surface area. The patterns of neighboring surface areas then need to fit together without any undesirable overlap or gap in between.

Another type of electrostatic deflector is known from EP 1993118. This type is a blanker deflector that uses an array of electrodes protruding from the substrate. This array is designed to be able to deflect in two directions at the same time and to enable individual addressing of the individual electrodes in the array; This latter feature results from the requirement that each beamlet in the blanker deflector be deflected separately. In order to allow any beamlet to pass through, there are holes in the substrate between the electrodes (one active, one ground or opposite polarity). These electrodes can be formed on two substrates that have a wall-shaped shape and are stacked together in such a way that they at least partially face each other. The height of these electrodes is about 35-50 μm, and the mutual distance may be less than 10 μm. If electrodes can be placed on the same substrate, this height can be less than 10 μm and their mutual distance can be about 0.5-2 times their height. The substrate can be thinned under the membrane with the protruding electrodes.

However, this type of deflector is limited, which provides insufficient uniformity if intended for application as a scanning deflector. The presence of one of the electrodes on the second substrate leads to the generation of stray fields and the generation of almost uncontrollable effects. This is not a problem for its use as blanker deflectors; If a potential difference is applied between the electrodes in the blanker deflector, the beamlet will be deflected to terminate at beam stop. Slightly larger or smaller deflections are not important as long as they terminate in any place at the beam stop. However, when applied as a scanning deflector, this change will immediately result in a reduction in the resolution of the provided pattern. In addition, the drift field can lead to a reduction in the homogeneity of the beamlets. This may result in insufficient resist development and / or wrong beam position and inappropriate (ie, failed) pattern generation here.

In short, this prior art has the disadvantage to be overcome by the present invention.

In a first aspect of the invention, a charged particle optical system is provided that includes an electrostatic deflector for deflecting one or more beamlets of charged particles. The deflector comprises first and second electrodes, through which the beamlets pass, wherein each of the electrodes comprises one or more strips, the strips being at least partially freestanding.

The deflector in the charged particle optical system of the present invention has the advantage that an electric field with a uniform field strength can be provided, at least in part due to its electrode comprising a freestanding strip. This good uniformity is based on the contribution from several effects: Firstly, the use of freestanding strips means the absence of continuous properties that can easily affect uniformity in a negative way. For example, insulating carriers can affect this system as parasitic capacitors. Moreover, freestanding electrodes can be made in a single etching step. This can reduce the distance between the electrodes, whereby the potential voltage difference on the electrode can be reduced. This reduction, in particular when applied in combination with high scanning frequencies above 100 kHz, preferably in the range of 300-3000 kHz, more preferably 500 to 1500 kHz, again leads to better uniformity of the deflector. do.

In addition, the strip may be provided with a relatively large surface area on the side of the strip that is perpendicular to the direction of the electric field. Providing such a large surface area will further improve the mechanical stability of the freestanding strip. As a result of this, the contribution of the electric field spanned up between two opposing strips is large compared to that of the stray configuration of the electric field. This is advantageous because the stray configuration is difficult to anticipate and control, thus causing deviation of the intended beamlet trajectory. Overall, the deflection is better controlled.

Suitably, this field is uniform across the grid of beamlets instead of addressing a single beamlet individually. Because of these features, the deflector is particularly advantageous for scanning deflection operations, and of course any other use is not excluded. In particular its fine precision and homogeneous output allows its use for other deflection and / or filtering operations.

In a suitable embodiment, these strips are located at a small distance relative to each other relative to the surface area facing the opposite strip, for example each electrode comprises one or more strips, said strips actually extending in parallel and passing through windows. A plurality of beamlets pass through the passage window, the passage window having a width in a direction perpendicular to the strip, and an electric field in this direction is generated in setting the potential difference between the electrodes, the strip Has a height, a width and a lateral direction, the three directions are perpendicular to each other and the height of the strip is greater than the width of the passing window. This provides a large direct field and good uniformity of the field compared to the drifting field.

Moreover, relatively short distances allow for relatively small driving voltages while meeting the requirements of the deflection angle. Designs with small driving voltages, for example designs with voltages less than 10V, are valid for one or more reasons; First, a driving electronic device that provides a voltage at a switching frequency of 1 MHz or more can be kept relatively simple; There is no need for any dedicated high voltage power transistors that can consume a lot of power and / or make up a configuration with a lifetime that can be critical and limited overall. In addition, with a small voltage, the risk of uncontrolled discharge between the electrodes that effectively damages is greatly reduced. This is excellent because of the reliability and robustness.

In a further embodiment, there are a plurality of pass-through windows, wherein the orientation of the electric field of each pass-through window is the same. Scanning in a single orientation simplifies the provision of patterning data for the beamlets. This whole provides high accuracy of the scanning process and provides improved stitching of lines and / or pixels scanned by different beamlets. The term 'orientation' is used herein in contrast to the term 'direction': there are three Cartesian directions x, y, z and the two orientations are coupled in one direction. The term 'same orientation' is not intended to mean that the electric field of one passing window has a constant in time. Effectively, the orientation of the electric field is preferably reversed within one single scanning period. However, this term is intended that the electric fields of one different pass window at any instant in time have the same orientation. Preferably, the electric fields of the different passing windows also have the same magnitude at any instant in time.

Suitably, the separation domain, preferably the separation window, is between the first and second pass-through windows. This will surely produce a pass window with the same directed electric field. Surprisingly, it has been found that even with the addition of this separation window certain pitches between beamlets can be met. This exhibits the beneficial effect of the use of freestanding electrode strips, preferably located at short distances from one another. The term 'short distance' refers herein to a short distance, as compared to the distance of the electrode in the prior art macroscopic deflector, as well as other sizes in the deflector such as the height of the strips and / or the distance between neighboring passing windows. Used for.

Suitably, there is one or more terminating resistances. This termination resistor accelerates the position of the beamlet between the first and second scanning periods. The term 'positioning' here means in particular the positioning of the beamlet relative to the starting position for scanning of the subsequent line during the second scanning period. Here, the beamlets are deflected in the same orientation, in both the first and second scanning periods and preferably in all the scanning periods. Positioning of the beamlets without simultaneous writing is achieved by bringing the voltage on the electrode to the starting value corresponding to the starting position and further by switching off the beamlets upwards during operation of the beamlet blanker in the column. do. Deflection of beamlets of the same orientation in subsequent scanning periods simplifies the provision of patterning data for the beamlets. Most suitably, all beamlets are deflected in the same orientation.

In a first implementation, the termination resistor is electrically coupled in parallel to the electrode system. In a second implementation, the first termination resistor is electrically coupled between the first electrode and the ground portion and the second termination resistor is electrically coupled between the second electrode and the ground portion. In one of these implementations, the provision of the termination resistor attenuates the parasitic capacitance in the deflector, which tends to slow down any switchback of the potential difference. It does not exclude the use of a combination of first and second transitions. This termination resistor is suitably integrated into the deflector; Examples include resistors of polysilicon, TaN, TiWN, CrSi, which are typically applied to passive and active integrated circuits.

In another embodiment, an edge zone is present that is at least partially disposed over the hole in the substrate. This edge zone comprises a strip of electrodes to form an electric field in the same orientation as the above mentioned electric field, but without the passing window of the beamlet. Suitably this edge zone is implemented as an extension of an interdigitated pair of electrodes. However, the beamlets are designed to be absent. The addition of such edge zones is very beneficial for the uniformity of the electric field. Most advantageous is a design in which the first and second electrodes are arranged at voltages of opposite polarity and additional ground electrodes are contiguously defined in the electrode system.

In a further embodiment, the freestanding electrode is covered with a coating to provide an electrically actually homogeneous surface. This coating is to prevent local changes in the surface structure from being somewhat active to establish the electric field between the electrodes. In addition, this contributes to the uniformity of the electric field. Moreover, this homogeneity tends to reduce the risk of electrostatic discharge.

In yet another embodiment, there is a second electrostatic deflector that deflects in a different direction than the first deflector. The different direction may be a direction opposite or perpendicular to the scanning direction, or may be any direction different from the scanning direction. In particular in the direction in the optical plane (for example, the plane in which the optical axis emerges perpendicularly). Calibration perpendicular to the scanning direction is useful in view of the simultaneous progressive movement of the lithography system with respect to the target surface. This movement is also called mechanical scan and is suitably in the same direction as the direction of the additional deflector. This calibration is suitably performed at a lower frequency than the scanning frequency. Deflection in the opposite direction to the scanning direction is suitably carried out with the same type of deflector used for scanning. In fact, this bias is part of scanning. Along with this, the beamlet passes through the center of the optical axis in the effective lens plane of the projection lens array even when deflected. In this way, spherical aberration caused by deflection through the projection lens array is reduced.

In a second aspect of the invention, a charged particle optical system is provided that includes a scanning electrostatic deflector for deflecting one or more beamlets of charged particles. The deflector comprises first and second electrodes, between which the beamlets pass through a passing window and, where present, are deflected under the action of an electric field between the electrodes, where a plurality of passing windows exist, each The orientation of the electric field of the passing window is the same.

Scanning of a single orientation simplifies the provision of patterning data for the beamlets. This in turn provides a higher accuracy of the scattering process and provides improved stitching of the lines and / or pixels scanned by the different beamlets.

More specifically, the deflector is designed to have a substantially uniform electric field in the active region of the deflector. Surprisingly, although electrodes are formed in this active region, it is possible to obtain a deflector with a uniform electric field. Any potential field disturbers, such as interconnects and capacitors, are formed outside the active region. In addition, an edge zone that bounds the active area that flattens non-uniformity because of the edge effect can be specified. In one embodiment, this field outside the active area is suppressed. Such inhibition is achieved, for example, by the provision of a separation material. In a preferred embodiment, this field only occurs within the active area.

One preferred embodiment of achieving work only in the active area is the use of interdigitated pairs of strip-shaped shaped electrodes. Another way of getting this work is in the structure, where the active area is formed by the absence of the underlying carrier. The absence of this underlying carrier immediately means that the field in the area is not disturbed by any unavoidable interaction with the underlying carrier. Most suitably, a combination of the two approaches is applied. An excellent way of this is the provision of freestanding electrode strips.

In a third aspect of the invention, the use of a charged particle optical system is provided. Suitably, this deflector is used for deflection of one or more beamlets of charged particles. Preferably, this deflector is used for deflection of the plurality of beamlets. The voltages of opposite polarities for the first and second electrodes of the deflector are most suitable. Driving the deflector with a reverse voltage around the ground value (0 volts or some other value) gives the best results. It should be understood here that the voltage on the electrode varies according to a predetermined voltage profile for proper scanning. The tooth profile is very advantageous, especially in combination with structures in which the electric field has the same orientation at any place in the deflector. According to the invention, the opposite voltage on the electrodes is preferably the same in magnitude and smaller than 10V. 10V is here the maximum applied voltage difference from the ground to the anode; This will be -10V for the cathode. More suitably, this voltage is much smaller, for example with a maximum voltage of 7, 5 or 4 volts. This small voltage is achieved through the deflector of the present invention, wherein self-standing electrodes at short distances from each other provide deflection strengths similar to those of prior art deflectors. Most preferably, this scanning frequency is relatively large, suitably in the RF range, most preferably an intermediate RF of 300 to 3000 kHz, for example 0.5-1.2 MHz.

Suitably, the (modulated) beamlet is located at the starting position in the positioning period without exposing the target surface and is deflected from the starting position in the writing period. This alternation of positioning and scanning is made particularly as a tooth profile. This improves the uniformity of the scanning.

Most suitably, this scanning frequency is in radio frequency (RF) and each beamlet is deflected in the same orientation as the other beamlets in the scanning period and in the subsequent scanning period; And the positioning period is shorter than the writing period. Here, one has achieved that by suppressing the parasitic capacitance, the pattern can be accurately scanned at a sufficient speed including high frequency scanning in one direction combined with a reduction in positioning time.

This use is particularly used in the method of projecting a predetermined pattern onto a target surface by a maskless lithography system. Along with this is applied for scanning the pattern on the target surface. The method includes generating a plurality of beamlets; Projecting the size of the beamlet using adjustment means provided with data of a predetermined pattern retrieved from the data storage; Focusing the adjusted beamlet on a target surface using focusing means, and scanning the pattern on the target surface by electrostatically deflecting the adjusted beamlet.

In a further aspect of the invention, the electrostatic deflector comprises first and second electrodes, which are at least partially self-supporting, the deflector deflecting the plurality of beamlets by the action of an electric field between the electrodes, and between the electrodes. The plurality of beamlets pass, the plurality of beamlets form a pass window, the size of the pass window in a direction transverse to the first direction matches the diameter of the beamlet, and the pass window extends in the first direction And the plurality of beamlets are arranged in a single row, the single row extending in the first direction, wherein a substantial portion of the electrostatic deflector extends beyond the pass window in the first direction. Preferably said substantial portion extends in said first direction at several times the pitch of the beam of said passing window. The deflector deflects a beamlet transverse to the first direction over a subdivision in the surface of the target, such as a field on a wafer, wherein the deflector is a scanning deflector for performing a final writing projection of the system.

For clarity, any of the embodiments described above and claimed in one of the dependent claims may be combined with any aspect of the invention specified in the independent claims.

And other aspects of the invention will be further described with reference to the drawings:
1 shows a simplified schematic of an embodiment of a charged particle multi-beamlet lithography system.
Figure 2 shows a plan view of one preferred embodiment of the present invention.
3 shows the detail of FIG. 2 as an enlarged view.
4 shows a schematic cross-sectional view of the embodiment of FIG. 2.
5 shows a schematic cross-sectional view of the embodiment of FIG. 2 in a direction perpendicular to the embodiment of FIG. 4.
6 shows a plan view of a second embodiment according to the invention.
7 shows a third embodiment according to the invention.
8 is a simplified diagram of a cross-sectional view of a deflector system with a knitting machine according to the present invention.
9 shows a simplified schematic cross-sectional view of a portion of the electrostatic deflector of the present invention.
10 is a schematic cross-sectional view of a portion of a prior art electrostatic deflector.

In the drawings, like reference numerals refer to the same or at least similar technical features. These drawings are not drawn to scale, but for illustrative purposes only. These figures show examples which are not intended to limit the claims in any way.

1 shows a simplified schematic diagram of one embodiment of a charged particle multi-beamlet lithography system based on an electron beam optical system without a common crossover of all of the electron beamlets. Such lithographic systems are described, for example, in US Pat. Nos. 6,897,458 and 6,958,804 and 7.084,414 and 7,129,502, which are incorporated herein by reference in their entirety and are assigned to the owners of the present invention. Such lithographic systems include a beamlet generator for generating a plurality of beamlets; A beamlet adjuster for patterning the beamlets into adjusted beamlets; And a beamlet projector for projecting the beamlet on the surface of the target. The beamlet generator typically includes a source and one or more aperture arrays. The beamlet adjuster is a beamlet blanker as a whole, with a blanking deflector array and a beam stop array. Beamlet projectors generally include a scanning deflector and a projection lens system.

Lithographic systems suitably include the function of redundancy scan. This function is known from WO-A 2007/013802, which is assigned to the assignee of the present application and incorporated herein by reference. In accordance with this function, compensation for the disable, that is, compensation for the invalid beamlet, is provided. Here, the reliability of the lithography system can be greatly increased. In addition to the above elements, a lithographic system for redundant scanning may include a sensor and a control unit coupled thereto to identify an invalid beamlet of a characteristic outside of predetermined specifications. This control unit is coupled to the system control to switch on or off of a particular beamlet and to operate the system relative to the target or vice versa to replace the invalid beamlet with the effective beamlet. Preferably, projection of any invalid beamlets is blocked. Along with this, an unwritten pattern element remains. The unrecorded pattern element is then transferred to the target surface by scanning an effective replacement beamlet on the surface.

As will be clear from the description below, the lithographic system 1 of the present invention is well suited for implementing a redundant scan function. Because of the achieved improvement in the accuracy of the scanning line to the target surface, a second scan can be executed that accurately fills the open gap in the first scanning order.

In the embodiment shown in FIG. 1, the lithographic system comprises an electron source 3 for producing an expanding electron beam 4. The beam energy is preferably kept relatively low in the range of about 1 to 10 keV. To achieve this, the acceleration voltage is preferably low and the electron emission source is preferably maintained at about −1 to −10 kV relative to the target at ground potential, and other settings may also be used.

The electron beam 4 from the electron source 3 passes through a double octopole and subsequently through a collimator lens 5 which collimates the electron beam 4. As will be appreciated, the collimator lens 5 can be any type of collimation optical system. Subsequently, the electron beam 4 impinges on the beam splitter, which in one suitable embodiment is in the hole array 6. This hole array 6 blocks a portion of the beam and allows a plurality of beamlets 7 to pass through the hole array 6. Preferably, the array of holes includes a plate having through holes. Thus, a plurality of parallel electron beamlets 7 are produced. This system produces a large number of beamlets 7, preferably about 10,000 to 1,000,000 beamlets, and of course it is possible to use more or fewer beamlets. Other known methods can also be used to make collimated beamlets.

The plurality of electron beamlets 7 pass through a condenser lens array (not shown), which concentrates each electron beamlet 7 in the plane of the beamlet blanker array 9. This beamlet blanker array 9 preferably comprises a plurality of blankers, each of which can deflect one or more electron beamlets 7. This beamlet blanker array 9 together with the beam stop array 10 constitutes modulating means 8. Based on the input from the control unit 60, the adjustment means 8 adds a pattern to the electron beamlet 7. The pattern will be located on the target surface 13 by the configuration in the end module.

In this embodiment, the beam stop array 10 includes an array of holes through which the beamlets can pass. The beam stop array, in its basic form, comprises a substrate, which has through holes, which are typically round holes, of course other shapes may be used. In one embodiment, the substrate of the beam stop array 8 has an array of regularly spaced through holes formed of a silicon wafer and can be coated with a surface layer of metal to prevent surface charging. have. In one embodiment, this metal is of a type that does not form a naturally-oxide skin such as CrMo.

In one embodiment, the passages of the beam stop array 10 are aligned with the elements of the beamlet blanker array 9. The beamlet blanker array 9 and the beamlet stop array 10 together block or pass the beamlet 7. If the beamlet blanker array 9 deflects the beamlets, it will not penetrate the corresponding aperture of the beamlet stop array 10, but will instead be blocked by the substrate of the beamlet block array 10. However, if the beamlet blanker array 9 does not deflect the beamlets, then the beamlets will penetrate the corresponding holes of the beamlet stop array 10 and then be projected as spots on the target surface 13 of the target 24. will be.

The lithographic system also includes a control unit 60, which comprises a data storage 61, a reading unit 62 and a data converter 63. This control unit 60 may be located far from the rest of the system, for example outside of the interior of the cleaning chamber. Using the optical fiber 64, a coordinated light beam with pattern data is transmitted to the projector 65, which transmits the end of the fiber (illustrated schematically at the plate 15) to the electro-optical unit 18, Here it is projected onto the adjustment array 9. The light beam 8 adjusted from each optical fiber end is projected onto the photosensitive element of the regulator on the beamlet blanker array 9. Each light beam 14 has a portion of the pattern data to control one or more regulators. Appropriately, a transmission means 17 is used in which the projector 65 is properly aligned with the plate 15 at the end of the fiber.

Subsequently, the electron beamlet 7 enters the end module. In this specification, the term 'beamlet' is referred to as adjusted beamlet. This adjusted beamlet effectively includes sequential parts over time. Some of these sequential parts, ie the parts stationary at the beam stop, may have lower intensity and preferably have zero intensity. Some portions will have zero intensity to allow positioning of the beamlet to the starting position for subsequent scanning periods.

The end module is construed as a replaceable unit, preferably insertable, which comprises several configurations. In this embodiment, the end module comprises a beam stop array 10, a scanning deflector array 11, and a projection lens arrangement 12, which of course not all of these should be included in the end module, but they It may be arranged otherwise. This terminal module will, among other functions, provide a reduction in the range of about 100 to 500 times, preferably as large as possible, for example 300 to 500 times. The end module preferably deflects the beamlets as described below. After leaving the end module, the beamlets 7 affect the target surface 13 located in the target plane. For lithographic applications, the target generally includes a wafer provided with a charged-particle sensitive layer or resist layer.

After passing through the beamlet stop array 10, the resultant adjusted beamlet 7 passes through the scanning deflector array 11, and the scanning deflector array passes in the X and / or Y direction, substantially unbiased beamlets ( It is provided for the deflection of each beamlet 7 perpendicular to the direction of 7). In the present invention, the deflector array 11 is a scanning electrostatic deflector, which allows the application of a relatively small driving voltage, which will be described later. The beamlet 21 then passes through the projection lens arrangement 12 and is projected onto the target surface 13 of the target, typically the wafer, in the target plane. This projection lens arrangement 12 focuses the beamlets, resulting in geometric spot sizes of diameters of preferably 10 to 30 nanometers. The projection lens arrangement 12 of this design preferably provides about 100 to 500 times reduction. In this preferred embodiment, the projection lens arrangement 12 is advantageously located close to the target surface 13. In another embodiment, the protective means may be located between the target surface 13 and the focusing projection lens arrangement 12. The protective means may be a foil or plate which is surely provided with the necessary holes and absorbs the released resist particles before the released resist particles can reach any sensitive elements in the lithography system. Alternatively or in addition, a scanning deflection array 9 may be provided between the projection lens arrangement 12 and the target surface 13.

In rough terms, the projection lens arrangement 12 focuses the beamlet 7 on the target surface 13. In addition, this further ensures that the spot size of a single pixel is accurate. The scanning deflector 11 deflects the beamlet 7 over the target surface 13. Here, it is necessary for the position of the pixel on the target surface 13 to be accurate to microscale. In particular, the operation of the scanning deflector 11 needs to ensure that the pixel fits well into the grid of pixels that ultimately make up the pattern on the target surface 13. It will be appreciated that macroscale positioning of the pixel on the target surface may be appropriately achieved by wafer positioning means located below the target 13.

Such high-quality projection relates to achieving a lithography system that provides reproducible results. Typically, target surface 13 comprises a resist film on a substrate. A portion of the resist film will be chemically modified by the application of charged particles, ie beamlets of electrons. As a result of this, the radiated part of the film will be more or less soluble in the developer and will provide a resist pattern on the wafer. The resist pattern on the wafer may subsequently be transferred to the underlying layer, ie, by the implementation, etching and / or deposition steps known in the semiconductor fabrication arts. Obviously, if the irradiation is not uniform, the register may not be developed in a uniform manner, which may lead to a mistake of the pattern. Moreover, many such lithography systems use a plurality of beamlets. No difference in investigation should result from the bias phase.

The present invention addresses the purpose of accurate and uniform projection of a plurality of scanning beamlets on this target surface 13. Here, it is understood that at least the freestanding electrodes in the scanning deflector 11 enable the generation of a very uniform electric field, where it can provide a uniform deflection to meet its purpose. In addition, it becomes possible to manufacture freestanding electrodes with adequate mechanical strength and without raising new engineering problems that are much more difficult to solve. In one suitable embodiment, the freestanding electrode had one or more mechanical resonance frequencies that were suitably low and / or high of the selected operating frequency of the scanning deflector. In other words, in this embodiment, providing a voltage difference for the electrodes does not induce vibration of the freestanding electrodes. This vibration will be the end of the uniform field between the electrodes. In particular, in one embodiment, the freestanding electrodes were provided with a surface structure, which provided only minor fluctuations and / or disturbances in the electric field.

2 shows a plan view of a preferred embodiment of the electrostatic scanning deflector 11 of the present invention. 3 shows an enlarged view of a portion of FIG. 2. 4 shows a schematic cross section in a first direction. FIG. 5 shows a schematic cross sectional view in a vertical direction with respect to the view of FIG. 4. 9 shows a simple diagram.

2 shows a plurality of continuous strips 31-38, which are part of each of the comb-structured first electrode 21 or the comb-structured second electrode 22. In this embodiment, the strips 31-38 together form an interdigitated pair of electrodes; This will then be referred to as the electrode system. The substrate 50 here supports the electrode system; However, this electrode system is at least partially and suitably overlaid over the apertures 51 in the substrate 50. For clarity, FIG. 4 only shows the continuous strips 31-35, but it is observed that this reduced number of strips properly illustrates the principle. Suitably, the continuous strips form a bridge extending from the first side 101 of the hole 51 to the second side 102. However, as shown with reference to FIG. 7, this is not deemed necessary.

For the sake of clarity, it is observed that the field is effectively made in the active area 20 as indicated by the dashed line in FIG. 2. The freestanding electrode of this embodiment creates a field primarily through its sides. There is no such aspect outside the active area 20. However, active region 20 may alternatively be formed. The term 'at least partially freestanding electrode' is meant to indicate that any part of the relevant conductors present in the active region is self-supporting or partially self-supporting. The term 'independent' is meant to indicate that these conductors are not supported by any membrane or other carrier in the active region. The term 'partially self-supporting' is intended to indicate the state in which these conductors are supported by membranes, by mechanical posts, or by any other supporting structure, locally and / or over a limited area. In a preferred embodiment, the term at least partially freestanding electrode means that the continuous strip is freestanding in the active region.

The windows 40, 41 extend between the strips. Some of these are pass-through windows 40; Others are the isolation domains 41. In this preferred embodiment, the isolation domain 41 is a window, for example free space not filled with any dielectric or other material. The passing window 40 has a width b. Passing window 40 is a window configured to allow beamlet 7 to pass through it. The passing windows can be grooves that extend completely between the strips of holes or electrodes designed for the couple of beamlets 7. If the passing window 40 is limited to a couple of beamlets 7, this limitation may also be due to the provision of a support structure (such as a post or beam extending for example perpendicular to the strip). However, there may be other reasons for limiting the passing window 40. Providing a relatively long pass window, however, is beneficial in obtaining maximum uniformity; Any interruption or restriction of the passing window will cause a change in the electric field.

Preferably, the number of continuous strips is relatively large and their mutual distance is short. The strips 31-38 have a lateral dimension, a width a, and a height z. The separating window 41 has a width c. Suitably, the width b of the passing window 40 is less than the total distance 2a + c between the passing windows 40. More suitably, the width b of the pass window 40 is selected such that at most three rows of the electron beamlets 7 pass through the pass window 40. More preferably, the number of columns is two and more preferably the number of columns is one. The reduction in the number of columns appears to be beneficial for the creation of a uniform field. This field line mostly runs in a direction perpendicular to the lateral extension of the strips 31-38. This is a clear improvement over the prior art macroscopic deflectors with two, for example U-electrodes, on opposite sides of the hole. The field strength of this deflector is not uniform. Especially near the corner of the electrode, the field strength is higher and the sides lead to disturbance of the electric field in any way. In the scanning deflector 11 according to the invention, the field strength is extremely uniform and obviously more uniform than in the prior art. The scanning deflector demonstrates a change in deflection intensity of less than 5%, more preferably less than 3%, and most preferably less than 2%. In one embodiment of the invention, a change in deflection strength of 1 to 1.5% was achieved.

As a result of this short width b of the passing window 40, while achieving a sufficient deflection angle, the potential differences 21, 22 on the electrodes can be relatively reduced.

Reduction of the potential difference over the electrodes has a major advantage. First, the deflector can be electrically driven in a better way; That is, the provision of a variable voltage difference for the electrode can be increased in speed and / or higher in bandwidth. The term 'bandwidth' is used herein as a measure of the uniformity of the application of an electrical signal. Too narrow a bandwidth can cause problems such as a change in the magnitude of the voltage difference and a change in timing that gives the voltage difference and an uncontrollable delay. Secondly, the risk of damage to the deflector as a result of pruning discharge is reduced.

In order to optimize the stiffness, the height z of the strip 31 is designed relatively large. Suitably, the height z is greater than the width b of the passing window 40. Moreover, the greater height functions to increase the so-called deflection strength or alternatively to reduce the required potential difference for a given deflection angle.

9 is a simplified cross-sectional view of a portion of an electrostatic deflector according to the present invention. Prior art Comparison with FIG. 10 will explain the major improvements made in the present invention. First, in the deflector the field extends directly from the first electrode to the second electrode; In the prior art it extends over the electrodes. Thus, resulting in greater uniformity and better controlled field strength. Secondly, the height z of the electrodes 31-36 is greater in the present invention than in the prior art. Since the beamlet 7 is deflected in the present invention over the entire height z, this deflection occurs more gradually. The field strength required for the preformed deflection angle can thus be reduced. Preferably, as seen in this figure, the height z is greater than the width b of the passing window 40. Third, the deflector of the present invention includes a separating window 41 in addition to the passing window 40. This allows the beamlets 7 to all deflect in the same direction herein. In the prior art shown in FIG. 10, the beamlets 7 are deflected in opposite directions. Although the present invention thus has additional strips compared to the prior art of FIG. 10, the pitch between the first and second beamlets does not increase. If desired, the pitch may be reduced. This small pitch is one step towards a pattern of smaller critical dimensions in the lithographic system of the present invention. Although not shown in this figure or in FIG. 10, prior art deflectors include certain holes through which individual beamlets pass. In the present invention, the plurality of beamlets pass between the first and second strips. The structure of the deflector of the present invention as a series of freestanding strips does not require additional holes. In addition, instead of passing through individual holes, the passage of a plurality of beamlets between the first and second strips contributes to uniformity.

One of the advantages of the deflector of the present invention is the location of the ground electrode. This ground electrode 25 is not located adjacent to the positive or negatively charged electrode, but is located on the substrate in an area that is not disposed above or substantially above the hole. Here, the distance between this charged electrode and the ground electrode is much larger. This helps to meet the boundary condition, which means that no electrostatic discharge should occur with damage to destroy the deflector. As a result, because of the local member of the ground electrode, the continuous strips of the first and second electrodes 21, 22 can be located at a smaller distance. For clarity, it is confirmed that the potential of the ground electrode does not need to be the same as the ground potential in the ordinary environment (0V). For example, the ground electrode can be anything from -10 kV to +10 V, for example. This potential applied to the first and second electrodes 21, 22 is then the potential near this ground, for example -10 kV-/ + 10V. Suitably, the potential difference between the first and second electrodes 21, 22 is at most 50V, more suitably at most 20V and more suitably at most 10V. In various embodiments of the invention, potential differences of less than 10V, for example 8V, 6V, 5V, are obtained. These lower voltages are suitable because they allow for a strong, nevertheless fast but still high bandwidth driving circuit. Suitably, the bandwidth is at least five times the scanning frequency. The bandwidth of 10 times the scanning frequency gives a very reasonable result for uniformity. Suitably, the scanning frequency is at least 100 kHz, more preferably at least 500 kHz or even 1 MHz or more.

As shown in FIG. 2, a bond pad 28 is provided in this structure. This bond pad 28 is coupled to each electrode via interconnect 29. The interconnect 29 is between the ground plane region 25. This is particularly suitable for higher switching frequencies of about 500 kHz or more. RF effects then begin to be relevant. By implementing the interconnect as a waveguide, this RF aspect is actually suppressed. It is understood by those skilled in the art that other transmission line implementations (striplines, transmission lines, etc.) may alternatively be selected.

In one embodiment, as shown in FIG. 2, the orientation of the electric field in each pass window 40 is the same. Because of this same orientation of the electric field, the deflection of all beamlets 7 runs in the same orientation. As a result, this surface area as well as the shape of the projected grid of the beamlet 7 is the same or independent regardless of whether there is deflection. This principle is practiced in the embodiment shown in the following manner: the first electrode comprises first and third strips, while the second electrode comprises second and fourth strips. The first pass window is between the first and second strips. The second pass window is located between the third and fourth strips. However, the separation domain is between the second and third strips; In other words, the isolation domain has no passing window. This isolation domain is suitably a window for manufacturing reasons. Moreover, since this design can reduce the driving voltage, the risk of discharge is actually reduced.

In its further refinement, the terminating resistance is coupled in parallel to the electrode system of the first and second electrodes 21, 22. This termination resistor can be integrated into the substrate of the deflector. Alternatively, the termination resistor may be a separate configuration, such as one or more surface mountable resistors assembled separately. In this system, a parasitic dose is provided to eliminate any influence on the positioning time. Specifically, the resistance weakens the capacitance and / or resistance and the parasitic capacitances together act as a filter. As a result, the positioning period is shorter than the writing period is achieved. Together these define the time required for scanning one line, and here the scanning frequency.

Most suitably, this resistor is mechanically coupled to the heat removal path. This heat removal path may include a heatspreader, a heatsink, and the like. Most relevant is that there is a heat conduction path from the deflector in the vacuum vessel to a location outside the vacuum. The use of such a resistor is possible in that the potential difference on the electrode is relatively small because of the relatively low driving voltage. This means that heat dissipation for the resistance will be limited. The advantage of this resistance is that the potential difference on the electrode can be reduced more quickly. Effectively, the parasitic capacitance of the electrode system is attenuated by the resistor, where it does not correspond to this reduction in potential difference. This reduction in this potential difference directly corresponds to the reduced time of bringing the beamlet to its starting position for subsequent deflection. Here, this increases the scanning frequency.

4 and 5 show schematic cross-sectional views of the embodiment of FIG. 2. 4 shows much more clearly the mutual positioning of the holes 51 and the strips 31-38 in the substrate. 5 shows that the strip 31 extends from the first side 101 to the second side 102 opposite the hole 51 in this embodiment. In this structure, the electrode efficiently constructs a bridge covering the lower hole. It is a preferred structure from the viewpoint of mechanical stability. There is no membrane carrier which serves as a support for the strip above the hole 51, but the strips are at least partially freestanding. To be self-supporting, the strips have dimensions and stiffness that are such that they prevent the strips 31-38 from bending in a flexible and uncontrollable manner.

This structure is suitably manufactured based on a semiconductor substrate that can be selectively etched and patterned from its upper face and from its lower face. Silicon-on-insulator (SOI) substrates are very beneficial for this purpose; The buried oxide 52 here serves as an etch stop. Alternatively, etch stops can be made, as known in the art, with pn-junctions or other doping transitions. Taking an example of an SOI substrate: The electrodes will be made in the upper semiconductor layer (device layer) 53. The substrate 50 is made on the bottom semiconductor layer (handling wafer). The hole 51 can be made by any type of etching, such as dry etching and wet etching. Those skilled in the art will appreciate that the silicon wafer is preferably doped with p-type or n-type. Suitably, no pn-junction is present to prevent current generation in the freestanding electrode. This level of doping can be freely selected as known to those skilled in the art of etching and microfabrication.

Suitably, the freestanding electrode is provided with a coating 54. It is known that the addition of a coating further improves the uniformity of the electric field. Several materials can be used to improve flatness, including dielectrics and conductive materials. However, metal coatings are considered most suitable; In contrast to the coating of dielectric materials, metal coatings do not provide additional capacitance in the system. Methods for the application of metal coatings, including CVD, sputtering, electroplating, are known in the art. An adhesive layer can be used if desired. More suitably, the semiconductor material of the freestanding electrode is not oxidized prior to the provision of the metal coating. This metal coating may be provided on all surfaces of the freestanding electrode at the same time, for example by a suitable CVD process, but this is not considered necessary. Alternatively, it is also possible to apply the coating from the top and bottom sides while ensuring that any side is at least partially covered by the conductive material. In this embodiment, two different materials can be applied for the coating. Most preferably the freestanding electrode is fully electrically conductive.

Although silicon is well known and well suited for the production of freestanding electrodes, alternative materials and methods are not excluded. These alternatives include the formation of freestanding electrodes on top of the substrate, as applied for RF MEMS applications, and the use of alternative substrate materials may be used in place of SiC and SiGe in addition to (in particular as top layers) or instead of handling wafers of Si. It includes.

6 shows a plan view of a second embodiment according to the invention. This embodiment shows an interdigitated pair of electrodes 21, 22. Edge zone 23 is located on the opposite edge of deflector 11. Edge zone 23 comprises a set of parallel oriented strips of first and second electrodes 21, 22. Nevertheless, any passing window 40 is designed within the edge zone 23. Suitably the design of the strip is the same as the design in the main part of the deflector 9 but is not necessary. Although shown the same, the edge zones 23 can be implemented in different designs.

In addition to the edge zone 23 in the direction parallel to the electric field, it is advantageous to make the edge zone 26 in the direction perpendicular to the electric field, ie near the distal end of the freestanding portion of the electrode or strip. This edge zone 26 supports to prevent artifacts in the electric field as a result of the interaction of substrates and / or conductors such as lead and interconnects. Preferably, each of these edge zones has an extension of 2 to 20%, more preferably 4 to 12% of the side extension of the strip 31.

Suitably, the deflector 11 of the present invention is assembled with the projection lens arrangement 12. It can be achieved without the serious electrostatic discharge problem observed in the prior art planar deflector shown in FIG. Deflectors with at least partially freestanding electrode strips and more uniform fields show better withstanding electrostatic voltage. This deflector may be assembled directly on or near or below the projection lens arrangement 12.

The scanning deflector 11 of the present invention has an additional advantage in one embodiment, which is that the thickness of the deflector is smaller than the thickness of the conventional deflector. In essence, the overall thickness of the substrate 50 and the electrode may be less than 500 micrometers, preferably less than 300 micrometers. This enables the position of the deflector 11 near the projection lens arrangement 12. An alternative assembly in which the scanning deflector 11 is near the projection lens arrangement 12 is not excluded. As a result of the short distance to the projection lens arrangement 12, the beamlet 7 deflected by the scanning deflector 11 has an efficient center of rotation very close to the projection lens arrangement 12. As a result of this, the deviation of the projection lens arrangement 12 has a less (negative) effect on the spot size of the pixel.

7 shows a third embodiment according to the invention. In this embodiment, the electrode system includes several portions 91-94. In this example, the number is four but is not necessary or not limited. The number can be larger (eg 9 or 16) and smaller (2). This electrode system can be subdivided into a series of portions that compete with each other, instead of a plurality of blocks. Each of these portions comprises a continuous strip of electrodes 21, 22 disposed over the holes 51a-d in the substrate 50. In this embodiment, there are four holes 51a-d corresponding to four portions 91-94. However, this is not strictly necessary; The additional layer can serve as a carrier for the electrode system of all strips. The additional layer will be provided with holes 51a-d while being disposed over the holes 51 of the substrate 50. These holes 51a-d do not have to have a cubic cross section, for example, where the lateral extension can be greater than the width or vice versa. Suitably, a continuous strip on each of the parts forms an interdigitated pair of electrodes, but this is not necessary. Also as discussed previously other features may be applied here to each of the four parts.

8 is a schematic diagram of an embodiment of a scanning electrostatic deflection system according to the present invention. This embodiment includes a first electrostatic scanning deflector 11a and a second electrostatic scanning deflector 11b. According to the invention, at least one of the deflectors 11a, 11b is a deflector according to the invention. Suitably, all are scanning deflectors according to the invention. With this system design, it is achieved that the beamlet 7 passes through the central portion of the optical axis 0 in the effective lens plane 19 of the projection lens arrangement even when deflected. In this way, the spherical aberration caused by the deflection through the projection lens arrangement is further reduced compared to the arrangement with the single scanning deflector 11 according to the invention. An important improvement of this design is that the amount of deflection that can be used increases without compromising the spot size resolution. In this design, as shown in Fig. 8, the two deflectors 11a and 11b are located side by side, each having an opposite voltage at its electrode. For deflection purposes, the sine of this voltage of each deflector 11a, 11b is switched simultaneously. The centering of the deflected beamlets 7 near the optical axis 0 of the projection lens system and in the effective lens plane 19 is achieved by the distance d5 between the effective lens plane 19 of the projection lens arrangement and the deflector 9b. This is done by fine tuning the ratio of deflection angles in terms of perspective. The mutual distance d6 between the two deflectors 11a, 11b and the potential difference applied between the electrodes can also be used in this micro-tuning operation. The potential difference applied at the first scanning deflector 11a and the potential difference applied at the second scanning deflector 11b are here mutually coupled. They are changed in such a way that the pivot point of the beamlet 7 is on the optical axis side of the projection lens array and crosses the optical axis 0 of the projection lens system. In a suitable implementation, the driving circuits of the first and second deflectors 11a, 11b are controlled via a single controller thereto. Suitably, also part of the driving circuit, for example its part generating the scanning frequency, can be integrated or otherwise coupled together.

Thus, the first deflector 11a deflects the beamlet 7 at an angle α1 away from the optical axis 0, and the second deflector 11b is in the opposite direction and at an angle α2. Deflect back). In this way, the beamlet 7 is deflected over an angle α3 when it crosses the effective lens plane 19 of the projection lens arrangement.

In a further embodiment, although not shown in the figure, these holes are only under the passing window.

In a further aspect of the invention, a charged particle system is provided that includes a scanning electrostatic deflector for deflecting one or more beamlets of charged particles. The deflector comprises a first and a second electrode, between which the beamlet passes, wherein each electrode comprises one or more strips, the strips actually extending in parallel and forming a passing window, which A plurality of beamlets pass through, the passing window having a width in a direction perpendicular to the strip, in which electric field is generated by setting a potential difference between the electrodes, the strip having a height, width and lateral direction They are in three mutually perpendicular directions and the height of the strip is greater than the width of the passing window.

With this deflector, it was possible to obtain a deflection angle, which is within the same order as the deflection angle of the macroscopic deflector operating with much larger potential difference. This is surprising because the ratio of the potential difference between the deflector of the present invention and the prior art macroscopic deflector can be more than 5 and 10 or greater. Moreover, the elevated height reduces the drift field configuration of the electric field, which improves the linearity of the field and here the uniformity of the deflection. In addition, the entire deflector has been found to have a reduced thickness compared to the macroscopic deflector. As a result of this, the deflector of the present invention can be more easily assembled into the projection lens arrangement, providing reduced aberrations.

Suitably the deflector comprises a freestanding electrode strip.

In another aspect of the invention, a method of scanning a surface with a scanning frequency using an electrostatic deflector is provided. This deflector comprises a first and a second electrode, with a passing window between the electrodes. Here, each beamlet scans a line on the surface that is within a single scanning period. The scanning includes positioning of the beamlet to a starting position within one positioning period and includes deflecting the beamlet from the starting position by varying the electric field strength across the electrodes within the writing period. According to the invention, the scanning frequency is in the radio frequency (RF) range. The beamlets are deflected in the same direction in each scanning period. Each beamlet is deflected under the action of an electric field oriented in the orientation for each beamlet; Moreover, the positioning period is shorter than the writing period.

The present invention is effectively enabled for scanning in different regimes governed by different laws than the prior art. This control system is a system of high frequency scanning. More specifically, the high scanning frequency is a frequency within the radio frequency (RF) range, most suitably a frequency in its intermediate range of 300 to 3000 kHz. As a result of this, in order to prevent delays and non-uniformities due to the RF properties of the conductors and materials involved, this deflection needs to follow the laws of RF electronics technology. One salient RF characteristic is parasitic capacitance. Especially in the case of voltage changes and inversions, parasitic capacitances can introduce large delays. In addition, parasitic doses tend to lead to deformation of the field and here tend to lead to out-of-spec scanning.

The challenge observed by the inventors of the present invention therefore relates to a method of scanning a pattern at a sufficient speed without causing problems with the accuracy of the conveyed pattern.

Here, the inventors proposed to perform the scanning within the radio frequency range while deflecting the beamlet over only a relatively small angle. This smaller deflection angle provides better accuracy and allows the reduction of the applied voltage difference across the electrodes of the deflector. Moreover, in order to obtain adequate and reliable results for such high frequency scanning, the deflection was limited to a single orientation. This single orientation deflection requires more beam repositioning, which is time consuming. However, deflection in the opposite orientation led to differences in the surface area of the grid of the beamlets in the case of deflection and in the absence of deflection. Correction of this difference in surface area was considered impracticable at high frequencies. It was the inventor's insight to significantly reduce the reposition time of the beamlets by suppressing parasitic doses. At the same time, this suppression of parasitic doses has been found to reduce field deformation and improve scanning accuracy here.

Briefly, our solution of accurate scanning of patterns at sufficient speed included high frequency scanning in only one orientation combined with a reduction in reposition time by suppressing parasitic capacitance.

In one suitable embodiment of this, the sawtooth characteristic applies a voltage on the electrodes of the deflector. Accurate serrations can be tuned to optimize performance. Here, the reverse setting of the voltage, together with the mechanical repositioning of the target relative to the lithography system, which is carried out simultaneously, provides the desired repositioning.

In a further embodiment, this location time is reduced through damping and / or filtering parasitic capacitance. This filtering is suitably achieved by adding configurations to the deflector to achieve filtering performance. Filter topologies are known to those skilled in the art of pseudoelectronics. Examples include RC filters, RCL-filters, pi-filters, and LC filters and networks. Most suitably, use an RC filter. This can be done via a terminating resistor.

In a further embodiment, the voltage applied to the electrodes of the deflector is less than 10V. This voltage reduction is particularly related to reducing power loss as a result of the filtering. More suitably, the deflector of the present invention is used as a deflector operating at a small potential difference. With freestanding electrodes, this deflector further reduces the parasitic capacity of the deflector and thus supports the reduction.

Suitably, this location period has at most half the duration of the lighting period. More suitably, the location period has a period of less than 40%, more preferably less than 25% of the writing period.

In addition to the foregoing description and introduction, the present invention is directed to all non-exemplified illustrated descriptions and embodiments of the drawings that may be obtained directly or unambiguously by one skilled in the art, except for the claims below.

Optical axis 0
Lithography System 1
Electronic source 3
Beam 4
Collimated optical system represented by a lens 5
Beam splitter 6
Beamlet 7
Regulator unit 8
Beam Blanker Array 9
Beamlet Stop Array 10
Electrostatic Scanning Deflector Array 11
Projection Lens 12
Target surface 13
Light beam 14
Plate 15
Actuator 16
Unit 17
Electro-optical Unit 18
Lens plane 19
Active area 20
First electrode 21
Second electrode 22
Edge Zone 23
Grounding Electrode 25
Edge Zone 26
Target 24
Bond Pads 28
Interconnects 29
Strip 31-38
Pass through window 40
Detach Windows 41
Board 50
Opening 51
Openings 51a-d
Buried oxide layer 52
Handling Wafers 53
Metal Coating 54
Width b of through-window 40
Width a of the strip 31
Width c of separation window 41
Height z of strips 31
Control unit 60
Data storage 61
Reading unit 62
Data Converters 63
Fiber optic 64
Projector 65
Part 91-94
First side 101
2nd side 102
Strip 131, 132, 133 (Prior Art)

Claims (24)

A charged particle optical system comprising an electrostatic deflector for deflecting a plurality of beamlets of charged particles,
The electrostatic deflector comprises a first electrode and a second electrode, wherein the first electrode and the second electrode are at least partially freestanding, and the deflector is configured to determine an electric field between the first electrode and the second electrode. By acting to deflect the plurality of beamlets, the plurality of beamlets pass between the first electrode and the second electrode, the plurality of beamlets forming a passing window, and the passing window comprises: Extending in one direction, the plurality of beamlets arranged in a single row extending in the first direction and the size of the passing window in the direction crossing the first direction is consistent with the diameter of the beamlet and the electrostatic deflector A substantial portion of extends beyond the passage window in the first direction,
Charged particle optical system.
The method of claim 1,
The substantial portion extends in the first direction by several times the pitch of the beam in the pass window,
Charged particle optical system.
The method of claim 1,
The deflector deflects the beamlet transversely with respect to the first direction over a detail region in the surface of the target, such as a field on a wafer,
Charged particle optical system.
The method of claim 3, wherein
The deflector is a scanning deflector for performing a final writing projection of the system,
Charged particle optical system.
The method of claim 1,
The passing window has a width in a direction perpendicular to the strip, the electric field is generated in the vertical direction when setting the potential difference between the electrodes, the strips in height, width and side in three mutually perpendicular directions. Direction, the height of the strip being greater than the width of the passing window,
Charged particle optical system.
The method of claim 1,
The first electrode comprises first and third strips, the second electrode comprises second and fourth strips, and a pass window is between the first and second strips and the third and fourth strips. Between, and the domain between the second and third strips has no through window,
Charged particle optical system.
The method according to claim 6,
The domain is included as free space,
Charged particle optical system.
The method of claim 7, wherein
Each electrode comprising a plurality of strips extending in parallel, wherein the strips of the first and second electrodes constitute an interdigitated pair of electrodes;
Charged particle optical system.
The method of claim 8,
A plurality of pass-through windows are between the interdigitated electrodes, the orientation of the electric field in each pass-window being the same,
Charged particle optical system.
The method of claim 1,
The electric field between the electrodes is less than 100V,
Charged particle optical system.
The method of claim 10,
The electric field between the electrodes is less than 20V,
Charged particle optical system.
The method of claim 1,
The electrostatic deflector comprises an edge zone in a second direction perpendicular to the first direction, the edge zone comprising a strip of electrodes for forming an electric field in the same orientation as the electric field, but having a pass window having beamlets Do not have,
Charged particle optical system.
The method of claim 1,
Further comprising a second electrostatic deflector included upstream or downstream from the first electrostatic deflector, the second electrostatic deflector deflecting the beamlet in a direction or orientation different from the first deflector,
Charged particle system.
The method of claim 1,
The freestanding electrode is covered with a coating to provide an electrically substantially uniform surface,
Charged particle optical system.
The method of claim 14,
The coating is a metal coating,
Charged particle optical system.
The method of claim 1,
With termination resistors,
Charged particle optical system.
The method of claim 1,
The machine post is placed in or on the hole to mechanically support the one or more electrodes or strips of electrodes,
Charged particle optical system.
Use of the system as claimed in claim 1 for deflection of one or more beamlets of charged particles.
The method of claim 18,
Providing a voltage of opposite polarity to the first and second electrodes,
Usage.
The method of claim 18,
The voltage of the opposite polarity is equal in magnitude and less than 10V,
Usage.
21. The method according to claim 19 or 20,
The voltage is provided at a frequency in the range of 0 to 10 MHz,
Usage.
The method of claim 18,
The beamlet is located at the starting position in the positioning period and is biased from the starting position in the lighting period,
Usage.
The method of claim 22,
The scanning frequency is in the radio frequency (RF) range,
The beamlets are deflected in the same orientation in each scanning period;
Each beamlet is deflected under the action of the electric field, the electric field is oriented equally for each beamlet,
The positioning period is shorter than the writing period,
Usage.
A method of projecting a predetermined pattern onto a target surface by a maskless lithography system,
a. Generating a plurality of beamlets;
b. Adjusting the beamlet using adjustment means provided with data of a predetermined pattern retrieved from the data storage unit;
c. Focusing the adjusted beamlet on the target surface using focusing means;
d. Scanning the pattern on the target surface by electrostatically deflecting the adjusted beamlet,
The scanning step is carried out as in any one of claims 18 to 23,
A method of projecting a predetermined pattern onto a target surface by a maskless lithography system.

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