WO2006048353A1

WO2006048353A1 - Device for structuring a particle beam

Info

Publication number: WO2006048353A1
Application number: PCT/EP2005/054517
Authority: WO
Inventors: Hans-Joachim Döring; Joachim Heinitz
Original assignee: Leica Microsystems Lithography Gmbh
Priority date: 2004-11-03
Filing date: 2005-09-12
Publication date: 2006-05-11
Also published as: DE102004052995A1; TW200615998A

Abstract

The invention relates to a device (50) for structuring a particle beam (31), said particle beam (31) illuminating the device (50) in an at least partially plane manner. The inventive device (50) is provided with a plurality of successively mounted aperture plates (51, 52, 53, 54). In the direction of the particle beam (31), a first aperture plate (51) produces a plurality of partial beams from the plane particle beam through a plurality of openings (61). A second aperture plate (52) that has smaller openings (62) than the first aperture plate (51) is mounted downstream of the same. The inventive device is also provided with a third aperture plate (53), arranged downstream of the second aperture plate, followed by a fourth aperture plate (54) for field homogenisation.

Description

Device for structuring a particle beam

The invention relates to a device for structuring a particle beam. In particular, the invention relates to a device for structuring a particle beam, wherein the particle beam at least partially illuminates the device surface and the device is provided with a plurality of successively connected aperture plates.

U.S. U.S. Patent 4,153,843 discloses a multiple beam exposure system. For this purpose, a two-dimensional array with a plurality of openings is provided in the beam path of an electron beam exposure system. The array is illuminated areally by the electron beam and reduced to a substrate. Only a single aperture plate is provided, which generates the multiple individual electron beams from the planar illumination.

US patent application US 2003/0155534 A1 discloses a maskless exposure system for particle beams. A plurality of successively nested aperture plates produce a plurality of individual beams from an electron beam. The top two plates and the bottom plate have openings through which the electron beam passes. Each of the plates has a thickness of about 100 m and are separated from each other a distance of 100 m to 1 mm apart. Between the second plate and the lowermost plate, an array of correction lenses is provided, which is arranged in front of the last aperture plate.

U.S. U.S. Patent 5,144,142 discloses a particle beam system including an aperture plate for masking corresponding sub-beams.

The single aperture plate comprises m-rows and n-columns of apertures arranged two-dimensionally on a substrate. Every opening is one

Assigned pair of deflection electrodes. Further, n x m-bit shift registers are provided on the substrate to supply voltages corresponding to the pattern data to the m pairs of the deflection electrodes. The

Aperture plate is formed only as a single component.

The article "Programmable Aperture Plate for Maskless High-Throughput Nanolithography" by Berry et al., J. Vac., See Technol. B 15 (6), Nov / Dec 1997; pages 2382 to 2386, discloses a programmable aperture array, 3000 The pattern to be written is introduced from one side into the aperture plate system and pushed through to the other side, the aperture plate system comprising an aperture plate with the aperture plate corresponding deflection electrodes, wherein openings are distributed accordingly.

The invention has for its object to provide a device for structuring, a particle beam, which is inexpensive to produce and at the same time generates individual particle beams with a precisely defined Ouerschnittsform the particle beam.

This object is achieved by a device having the features of claim 1.

It is advantageous if the device for structuring a

Particle beam is illuminated at least partially flat. The device is provided with a plurality of successive aperture plates. In this case, as seen from the direction of the particle beam, a first aperture plate of the planar particle beam generates a plurality of partial beams through a multiplicity of openings. This is followed by a second aperture plate which has smaller openings than the first aperture plate. A third aperture plate, which is a blanking plate, is provided in front of a fourth aperture plate, which serves for field homogenization.

At this time, the first aperture plate, the second aperture plate, the third aperture plate and the fourth aperture plate are arranged so as to be aligned along each center of each aperture. Each of the openings in each of the aperture plates has a square section. The first aperture plate has a greater thickness than the second aperture plate.

Further, the openings in the second aperture plate are smaller than the openings in the first aperture plate, in the third aperture plate and in the fourth aperture plate.

In addition, the third aperture plate on the side facing away from the incident particle beam has a drive circuit, and a deflector for the particle beam assigned to each aperture. The deflector is an electrostatic deflector.

Further advantageous embodiments of the invention can be taken from the subclaims.

In the drawing, the subject invention is shown schematically and will be described with reference to the figures below. Showing:

Fig. 1 is a schematic representation of the structure of an entire

Systems for maskless electron beam lithography; and

Fig. 2 is a schematic representation of the device for

Structuring a particle beam.

Figure 1 shows schematically the structure of an entire system for maskless electron beam lithography. Although the following Although this description is limited to electron beams, this should not be construed as limiting the invention. It goes without saying that the invention is suitable for all particle beams.

From an electron gun 30, an electron beam 31 is generated, which propagates in the direction of an electron-optical axis 32. The from the

Electron gun 30 leaking electrons have a source crossover

31 o on. The electron gun 30 is followed by a beam centering device 33, which is the electron beam symmetrical about the optical axis

32 aligns. After the beam centering device, the electron beam 31 passes through a condenser system 10 which forms a parallel beam from the initially divergent electron beam 31. The beam formed by the condenser system 10 has a diameter over which the intensity is homogeneously distributed. After the condenser system 10, a planar object 34 is provided. The planar object 34 is an aperture plate or an aperture plate system 50. The aperture plate system 50 is provided with a plurality of openings for producing a plurality of parallel beams 36. In the propagation direction of the beam 36 towards the target 6 is followed by a baffle plate 35 having a plurality of beam deflection units. After the baffle plate 35 is followed by an accelerating lens 39, which increases the energy of the electrons in the electron beam 31 and then a first

Intermediate image of the crossover 31 ₁ generated at the location of the aperture 38. All individual crossovers of the partial beams 36 are formed at almost the same location, namely the aperture of the aperture stop 38. The diameter of the opening of the aperture stop 38 is selected so that almost all the electrons of the undeflected beam bundles 36 can pass through the aperture stop 38. Single beams 37, which have undergone an individual change of direction by the deflection plate 35, are stopped at the aperture stop 38, since their crossover intermediate image does not arise at the location of the aperture diaphragm opening. In the further course of the beam, at least one magnetic lens 40 now follows for the purpose of reducing the imaging of the aperture plate 34 onto the target 6. In the exemplary embodiment shown here, two magnetic lenses 40 are shown. In the Illustration creates a second intermediate image of the crossover 31 ₂ . Before the undeflected beams 36 strike the target 6, which is for example a wafer, they pass through an objective lens 41. The objective lens 41 is equipped with a plurality of elements. Before and after a second crossover 31 _{2 of} the electron beam 31 two deflectors 45 and 46 are provided. The deflectors 45 and 46 serve to deflect and position the electron beam 31 and the plurality of undeflected beams 36 in the target 6, respectively. The two independently controllable deflectors 45 and 46 are advantageously used to separately optimize slow and fast deflections. Fast sweeps in the megahertz-to-gigahertz frequency range are required, for example, to hold the position of the reduced aperture plate 34 on the uniformly moving target 6 constant for the duration of an exposure step or stroke by means of sawtooth deflections, and then jump to the next exposure point in a very short time. Since adjacent pixels are typically less than 100 microns away, the fast deflection system 46 is preferably constructed as an electrostatic system. For the compensation of low-frequency position deviations of the target 6 from the uniform movement in the range of a few micrometers, a slow but highly accurate magnetic deflection system 45 is preferably used. In order to minimize the deflection errors of the magnetic deflection system 45, this may be formed as a multi-level deflection system. Furthermore, stigmators 44 are provided, which are preferably constructed as multilayer magnetic coil systems to Astigmatismen and

To compensate for distortions that are caused in the optical column by manufacturing tolerances and adjustment errors. The objective lens 41 has a height measuring system 42 which scans at the landing point of the electron beam at the target 6. The height measuring system 42 serves to detect unevenness of the target 6 (for example wafers) and of

Altitude variations that a translation table can cause. A detector 43 for the particles or electrons backscattered by target 6 is located near the beam impingement point. This detector 43 serves the Position determination of marks on the target 6 for the purpose of covering several exposure planes or for calibrating control elements of an exposure system. Furthermore, three correction lens pairs 23, 24, 25 are located in the lower region of the corpuscular beam device 2. The correction lenses 23, 24, 25 serve for the dynamic correction of the focus, image field size and field rotation during the exposure of the continuously moving target 6. The correction lens system 23, 24 , 25 allows the correction of errors caused by height variations of the target, as well as by variable space charges in the column area.

FIG. 2 shows a schematic representation of a device 50 for structuring a particle beam 31. It should be noted that the particle beam 31 is to be equated with an electron beam. The device 50 for structuring the particle beam 31 comprises a first aperture plate 51, a second aperture plate 52, a third aperture plate 53 and a fourth aperture plate 54. The particle beam incident in the direction of the optical axis 32 illuminates the first aperture plate 51 over a large area. In the first aperture plate 51, a plurality of openings 61 are formed, which have a substantially square cross-section. The first aperture plate 51 is made of silicon and has a thickness 51 _D of about 20 μm to 100 m. The first aperture plate 51 is followed by a second aperture plate 52. Apertures 62 are also formed in the second aperture plate. The second aperture plate 52 is followed by a third aperture plate 53, in which also a plurality of openings 63 are formed. The third aperture plate 53 is followed by a fourth aperture plate 54, in which also a plurality of openings 64 are formed. All openings 61, 62, 63, 64 in the first aperture plate 51, in the second aperture plate 52, in the third aperture plate 53 and in the fourth aperture plate 54 have a square cross section. The opening 61 in the first aperture plate has a larger dimension 71 than the opening 62 in the second aperture plate 52. The first

Aperture plate 51 downstream aperture plate 52 has a thickness 52 _D of a few micrometers and the openings 62 have a highly accurate square cross section. High accuracy in this context means that the cross section complies with a tolerance <100nm for the absolute dimensional accuracy in x and y and the corner radii and the edge roughness <100nm. The openings 62 in the second aperture plate 52 have a dimension 72 which is smaller than the dimension 71 of the opening 61 in the first aperture plate 51. A typical ratio for the dimensions of the openings 71: 72 is 2 ... 3, assuming absolute dimensions of 6 ... 3μm for the opening 62. The first aperture plate 51 is, as already mentioned, illuminated area by the incident electron beam 31 and thereby generates through the openings 61 a plurality of partial beams, the cross-section of the

Cross section of the openings 61 in the first aperture plate 51 correspond. The first aperture plate 51 not only serves to generate a plurality of partial beams, but also serves to dissipate the excess heat generated by the incident electron beam 31. The partial beams produced by the first aperture plate 51 strike the second aperture plate 52, wherein the apertures 62 in the second aperture plate 52 produce the form-defined partial beam 80 required for imaging. The form-defined partial beam 80 impinges on the third aperture plate 53, in which openings 63 are formed, which likewise have a larger dimension 73 than the openings 62 in the second aperture plate 52. The third aperture plate 53 has a drive circuit on the side facing away from the incident particle beam 31 55, which generates the signals required for the deflection of the form-defined partial beam 80. The third aperture plate 53 has a thickness 53 _D of approximately 20 μm to 100 m. The fourth aperture plate 54 has a thickness 54 _D of about 20 μm to 100 m.

Likewise, at the side facing away from the incident particle beam 31 of the third aperture plate 53 of each opening 63, a deflector 56 for the shape-defined partial beam 80 is assigned. The third aperture plate 53 is followed by a fourth aperture plate 54, in which openings 64 are likewise provided which are approximately the same or slightly larger

Have dimension 74 as the openings 63 in the third aperture plate 53. The first aperture plate 51, the second aperture plate 52, the third aperture plate 53 and the fourth aperture plate 54 are arranged to each other such that all openings 61, 62, 63, 64 are aligned along a center axis 81.

Claims

claims

1 . A device (50) for structuring a particle beam (31) which illuminates the device (50) at least partially flat, and in which the device (50) with a plurality of successively connected aperture plates (51, 52, 53, 54) is provided , characterized in that from the direction of the particle beam (31), a first aperture plate (51) from the flat particle beam through a plurality of openings (61) generates a plurality of partial beams, a second aperture plate (52) having smaller openings (62) as the first aperture plate (51), a third aperture plate (53) being a blanking plate and a fourth aperture plate (54) for field homogenization.

2. Device according to claim 1, characterized in that the first aperture plate (51), the second aperture plate (52), the third aperture plate (53) and the fourth aperture plate (54) are arranged so that they along each of a center each opening (61, 62, 63, 64) are aligned.

3. Device according to claim 1, characterized in that the

Openings (61, 62, 63, 64) in each of the aperture plates (51, 52, 53, 54) have a square Ouerschnitt.

4. Device according to one of claims 1 to 3, characterized in that the first aperture plate (51) has a greater thickness (51 _D ), as the second aperture plate (52).

5. The device according to claim 4, characterized in that the ratio of the thickness (51 _D ) of the first aperture plate (51) to the thickness (52 _D ) of the second aperture plate (52) is between 3 and 10.

6. Device according to one of claims 1 to 5, characterized in that the ratio of the size of the openings (61) in the first aperture plate (51) to the size of the openings (62) in the second aperture plate (52) between 2 and 3 lies.

7. Device according to one of claims 1 to 6, characterized in that the openings (62) in the second aperture plate (52) are smaller than the openings (61, 63, 64) in the first aperture plate (51), in the third Aperture plate (53) and the fourth aperture plate (54).

8. Device according to one of claims 1 to 7, characterized in that the third aperture plate (53) on the incident particle beam (31) side facing away from a drive circuit (55) and each opening (63) associated deflector (56) for the Particle beam (31).

9. Apparatus according to claim 8, characterized in that the

Drive circuit (56) is designed in the form of an integrated electronics.

10. Device according to one of claims 1 to 7, characterized in that the particle beam (31) is an electron beam.