Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
  • G03F1/68—Preparation processes not covered by groups G03F1/20 - G03F1/50
  • G03F1/72—Repair or correction of mask defects
  • G03F1/74—Repair or correction of mask defects by charged particle beam [CPB], e.g. focused ion beam
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
  • G03F1/68—Preparation processes not covered by groups G03F1/20 - G03F1/50
  • G03F1/72—Repair or correction of mask defects
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
  • G03F1/68—Preparation processes not covered by groups G03F1/20 - G03F1/50

Definitions

• the present invention relates to a method for removing defect material in a transmissive region of a lithographic mask, which comprises transmitting carrier material and absorber material.
• the invention further relates to a lithographic mask having a transmissive area.
• photolithographic structuring methods are generally used.
• a radiation-sensitive photoresist layer is applied to a surface of the substrate wafer to be structured and exposed by means of electromagnetic radiation through a lithography mask.
• mask structures which are transmitted through adjacent and transmitting. are predetermined areas of the lithographic mask, imaged by means of a lens system on the photoresist layer and transferred by means of a subsequent development process in the photoresist layer.
• the photoresist layer structured in this way can be used directly as a mask in an etching process or an implantation doping for the production of electronic circuit structures in the surface of the substrate wafer.
• RET resolution enhancement techniques
• PSM phase shifting mask
• phase masks In contrast to standard chromium masks or binary masks, in which the structures to be imaged are reproduced by means of a structured absorptive chromium layer arranged on a transmitting support, phase masks differ in that they have two types of transmissive regions between which a phase difference of 180 ° exists. This results in a sharp light-dark transition of the exposure radiation transmitted through a phase mask at the edges of the mask structures, which leads to an improved resolving power.
• phase mask is the so-called alternating phase shifting mask (AItPSM), which alternately transmits regions of 0 ° phase and JP-hash or Ehase-ver-s-chiebun-g
• AItPSM alternating phase shifting mask
• phase shift regions are etched into the transmissive carrier material of the phase masks as a rule, whereby a transit time difference of the exposure radiation used and thus the desired phase shift of 180 ° is achieved.
• a major problem with alternating phase masks are leftover remnants of transmissive carrier material in the Phase shift ranges, which should be completely etched to achieve the phase shift of 180 ° actually.
• the cause of these residues referred to below as defect material, are above all excess residues of the absorber material or else particles which lie above the respective phase shift ranges to be produced before the etching of the transmitting carrier material.
• defects which are in or at the phase shift regions, cause a phase of 0 ° exposure radiation.
• the exposure radiation at the edges of the defects due to destructive interference is extinguished, causing the defects to be dark and therefore detrimental even at small lateral dimensions.
• the defects are particularly critical, especially in narrowly delimited or narrow phase shift regions, which are formed for example as lines or trenches or contact holes, as well as in so-called "180 ° phase assists.”
• Transparent or even partially or non-transparent defects with curved edges are also critical Surface in trenches of the mask.
• the absorbing regions of the phase masks are usually inspected prior to the etching of the transmissive carrier material with regard to excess absorber residues and if necessary repaired with a focused ion beam.
• residues of the absorber material can be overlooked and, moreover, that particles can be made to be produced phase shift regions of a phase mask between the inspection and the etching of the carrier material, by which the defects are formed.
• phase shift areas of alternating phase masks that have been produced by means of an atomic force microscope (AFM) and to detect interfering defect material by means of the measurement peak.
• plane of the atomic force microscope d. H . to remove in layers.
• the planed defect material is then removed in a cleaning process.
• AFM atomic force microscope
• the object of the present invention is to provide an improved method for removing defect material in a transmissive region of a lithographic mask as well as a defect-free lithography mask.
• a method for removing defect material in a transmissive region of a lithographic mask which has transmitting substrate material and absorber material.
• defect material and inherently intact absorber material are removed in a processing area and in a second process step an absorbing material is applied in an outer area, wherein the outer area depends on the portion of the processing area that was previously covered with absorber material. This eliminates the defect and restores the desired absorption geometry.
• the method according to the invention is based on initially removing both defect material and absorber material in a processing region and transmitting material arranged below the absorber material, and then applying absorbing material in an outer region to again form a predetermined transmittent region of desired phase shift on the lithography mask.
• the method according to the invention offers the possibility of reliably removing a defect in a transmissive region even in the case of limited space conditions, as present, for example, in holes or at trench ends.
• the method can be used in particular for eliminating defects in phase-shifting regions of alternating phase masks, but can also be used for defect removal on other lithographic masks, such as binary masks.
• a focused ion beam is used in the first process step for removing the defect material and the absorber material and optionally also the transmitting carrier material.
• This embodiment enables a simple and rapid removal of a defect in a transmissive region of a litho. graphiemaske.
• the relevant materials are preferably removed up to or below a plane which is predetermined by the bottom of the transmitting region.
• an auxiliary hole is formed adjacent to or in the vicinity of the transmitting region and subsequently defect material or defect material and absorber material and optionally transmissive carrier material are removed by means of a micro planer.
• the formation of an auxiliary hole creates a sufficient travel path for the micro planer used, which is, for example, the measuring tip of an atomic force microscope.
• this embodiment of the method is particularly suitable for removing defect material in a transmissive region of a lithography mask with limited space, for example at a trench end of a transmissive region present as a trench. Due to the
• a transmissive area repaired in this way has a bottom and side surfaces with a flat and smooth surface and straight edges.
• the respective mask materials according to the embodiment described above are preferably removed up to or below a plane which is predetermined by the bottom of the transmitting region.
• auxiliary holes are formed adjacent to and / or in the vicinity of opposite sides of the transmitting region. Subsequently, defect material or defect material and absorber material as well as optionally transmitting substrate material are removed with the aid of a micro planer.
• This embodiment can also be Partially used for removing a defect in a transmitting area with limited space available, as they are present for example in a narrow hole, as by means of the two auxiliary holes sufficient travel for the micro-plane is created.
• the lithographic mask after removal of the defect material or the defect material and the absorber material and, if appropriate, of the transmissive carrier material using the micro planer to an additional cleaning process. In this way, the material removed by the micro-planer is completely removed from the lithography mask.
• ions of the ion beam may be implanted in the transmissive region of the lithography mask, resulting in a reduction in the transmittance of the repaired transmissive region.
• the absorbing material is applied in the outer region or in the auxiliary holes in such a way that an enlarged transmission area of the lithographic mask is formed, which is larger than the original transmissive area.
• the area to be etched is possibly. a little larger from the outset than would be necessary to remove the defect.
• a transmissive region of a lithography mask repaired at an edge exhibits an increased transmission of exposure radiation compared to a defect-free ideal transmitting region.
• causes these effects is a reduced dispersion of Exposure radiation at the edge due to an edge structure deviating from an ideal edge structure after the defect removal.
• the method may be preferable for embodiments of the method to simulate the optical imaging behavior of the lithography mask before carrying out the second method step.
• the absorbent material can be applied according to a desired optimal imaging behavior.
• the mask geometry is used before and if necessary. measured during repair with methods of the prior art, ie z. With an optical microscope (AIMS), electron microscope, ion microscope or atomic force microscope.
• a lithography mask with a transmissive region is furthermore proposed in which defect material is removed by the method according to the invention or one of the preferred embodiments. Since defects can be removed reliably and, in particular, also in transmissive areas with limited space, with the aid of the method or the preferred embodiments, such a defect-free lithography mask is distinguished by good optical imaging behavior.
• such a lithographic mask has a transmissive region, which with respect to a surface of the lithographic mask is replaced by a respective one.
• several Absorbermateri- alien is enclosed, wherein the or the absorber materials are arranged in different horizontal planes on the lithography mask. The invention will be explained in more detail below with reference to FIGS. Show it :
• FIGS. 1 to 4 show a detail of a transmitting phase shift range of a phase mask with a defect and its removal according to a first embodiment of a method according to the invention, respectively in plan view and in a lateral sectional illustration;
• FIGS. 5 to 8 show a further transmitting phase shift range of a phase mask with a defect and its removal according to a second embodiment of a method according to the invention, in each case in plan view and in a lateral sectional view;
• FIG. 1 shows a detail of a transmissive phase shift region of an alternating phase mask, hereinafter referred to as transmitting region 1, in a schematic plan view and in a schematic
• the transmissive region 1 is present as a trench in a surface of the phase mask and, as can be seen from the plan view of FIG. 1, is bordered with respect to the surface by an absorber material 3 such as, for example, chromium.
• the transmissive region 1 has a width of, for example, 400 nm.
• the phase mask has a layer of a transnaittierenden carrier material 5 and another arranged between the absorber 3 and the substrate 5 layer of a transmissive carrier material 4.
• the carrier materials 4, 5 are the same transmitting material as, for example, quartz.
• the carrier material 4 not covered by the absorber material 3 is etched away to the surface of the carrier material 5 in order to produce the above-described phase shift of 180 ° of an electromagnetic radiation used in a lithographic exposure.
• the absorber 3 has, for example, a thickness of 80 nm.
• the layer of the transmissive carrier material 4 has, for example, a thickness of 170 nm in order to produce a phase shift of 180 ° at an exposure wavelength of 193 nm.
• FIG. 1 further shows a defect 40 at a trench end of the transmissive region 1, which emerges from a residue of non-etched-away carrier material 4.
• the cause of such a defect 40 is, for example, an excess residue of the absorber material 3 or a particle arranged on the carrier material 4 before the etching.
• this defect 40 results in a phase of exposure radiation of only 0 °, which extinguishes the exposure radiation at the edge of the defect 40 due to destructive interference.
• the defect 40 causes disturbing darkening of the edge or trench end during lithographic exposure.
• Corresponding darkening effects can also occur at phase shifts other than 0 ° due to a defect or scattering at the defect.
• an auxiliary hole 6 is etched by means of a focused ion beam.
• absorber material 3 and carrier material 4 and, as can be seen from FIG. 2, if appropriate, also a small part of the carrier material 5 are removed.
• the defect material 40 is removed by means of a micro planer (not shown).
• the defect material 40 is preferably in
• the measuring tip of an atomic force microscope acts as a microhob. This atomic force microscope can be used in advance for measuring the transmissive region 1 and the defect 40 at the same time.
• a layer of an absorbent material 7 having a thickness of, for example, 40 nm is applied to the exposed outer region or the auxiliary hole 6.
• the absorbent material 7 is preferably carbon or a metal such as chromium, which is deposited in the exterior area, for example, by means of a standard process. In this way, a new transmissive region 10 of the phase mask is formed.
• the absorbent material 7 protrudes into the original transmissive region 1, as a result of which the transmissive region 10 is laterally slightly smaller than the original transmissive region 1.
• the cause of this increased transmission is a reduced scattering of the exposure radiation due to a defect removal at the repaired defect-free trench end of the transmissive region 10 changed edge structure, which deviates from an ideal edge structure.
• phase mask it is preferable to subject the phase mask to an additional cleaning process prior to application of the absorbent material 7.
• the defect material 40 removed from the micro-planer is completely removed from the phase mask, so that the absorbent material 7 only on the substrate 5 and not in the auxiliary hole 6 or at the edge of the auxiliary hole 6 befindliches
• Defective material is applied.
• the displaced defect material can also be covered with absorber, if the repaired structure is then still stable against subsequent cleaning, or can be dispensed with such a cleaning.
• auxiliary hole 6 adjacent to the transmissive region as shown in Fig. 2
• auxiliary hole it is also possible to form the auxiliary hole at a short distance in the vicinity of the transmissive region.
• additional absorbent material 3 present between the defect 40 and the auxiliary hole 3 and support material 4 located below the absorber material 3 are also removed by means of the micro planer.
• FIG. 5 shows a further transmitting phase-shifting region of a phase mask, referred to below as a transposing region 2, with a defect 40, which in turn emerges from a residue of non-etched-off carrier material 4 at one end of the transmitting region 2.
• the transmissive region 2 embodied as a hole is correspondingly encompassed by an absorber material 3 such as, for example, chromium with respect to a surface of the phase mask and has, for example, a width of 400 nm and a length of 800 nm.
• an absorber material 3 such as, for example, chromium with respect to a surface of the phase mask and has, for example, a width of 400 nm and a length of 800 nm.
• the absorber 3 again has, for example, a thickness of 80 nm.
• the thickness of the layer of the transmitting carrier material 4 is again 170 nm, for example, in order to produce a phase shift of the exposure radiation of 180 ° at an exposure wavelength of 193 nm.
• two auxiliary holes 6 are formed by using a focused ion beam in an outer region on opposite sides of the transmitting region 2.
• absorber material 3 and carrier material 4 and optionally also a small part of the carrier material 5 are removed.
• the left auxiliary hole 6 is formed, for example, adjacent to the transmitting region 2 and the right auxiliary hole 6, for example, at a short distance near the transmitting region 2.
• both auxiliary holes 6 together adjacent to or in the vicinity of the transmitting region 2.
• the defect material 40 and the absorber material 3 located at the edge of the right auxiliary hole 6 and the substrate material 4 arranged below are removed by means of a micro planer, which may again be the measuring tip of an atomic force microscope.
• the materials in question are preferably pushed in the direction of or into the auxiliary holes 6.
• the outer area or the auxiliary holes 6 are covered, as shown in FIG. 8, with a layer of absorbent material 7 such as carbon or metal, so that one is transmitted - The area 20 is provided.
• the layer of absorbent material 7 again has a thickness of, for example, 40 nm.
• the repaired phase masks each have a transmissive region 10 or 20 which is in relation to a surface of the phase masks of an absorber material or in the case that the applied absorbent material 7 of the Absorber material 3 differs, is bordered by several absorber materials.
• the or the absorber materials are arranged in different horizontal planes on the phase masks.
• Figures 9 to 11 show the removal of the defect 40 in the formed as a hole transmitting region 2 of the phase mask according to a third embodiment of a method according to the invention, in which dispensed with the use of a micro planer.
• auxiliary hole 6 is formed, which occupies a relatively large portion of the transmissive region 2.
• This third embodiment of a method according to the invention can also be used for eliminating defects on transmissive areas with a different geometry. In this way, it would also be possible, for example, to remove the defect 40 in the transmissive region 1 shown in FIG. 1 as a trench.
• the transmissive region 21 is laterally slightly larger than the original transmissive region 2. In this way, a reduced transmission of exposure radiation in the transmitting region 21 is compensated.
• the cause of the reduced transmission are ions of the ion beam implanted in the transmissive region 21 which, as described above, are used in a relatively large portion of the original transmissive region 2 for material removal.
• the absorbing material 7 can then be applied in accordance with a desired optimum imaging behavior of the phase mask, so that an area which is larger or smaller than the original transmitting area is formed. It is also possible to form a transmissive area matching the dimensions of the original transmitting area.
• a common "aerial image measuring system” AIMS can be used.
• the method according to the invention or the described embodiments can be used not only for removing defect material in transmitting phase-shift regions of alternating phase masks.
• the method or the described embodiments can also be used for defect or. Material removal in transmitting areas with a phase of 0 ° and in principle also for material removal or for removing particles in the transmitting areas of other lithographic masks such For example, use binary lithography masks or reflective EUV masks.

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• General Physics & Mathematics (AREA)
• Preparing Plates And Mask In Photomechanical Process (AREA)

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• 2005
  • 2005-01-28 DE DE102005004070A patent/DE102005004070B3/de not_active Expired - Fee Related
  • 2005-12-30 TW TW094147731A patent/TW200627076A/zh unknown
• 2006
  • 2006-01-26 WO PCT/EP2006/000660 patent/WO2006079529A1/de active Application Filing
  • 2006-01-26 JP JP2007510047A patent/JP2007534993A/ja active Pending
  • 2006-01-26 EP EP06703614A patent/EP1842098A1/de active Pending
  • 2006-01-26 KR KR1020067026053A patent/KR100841036B1/ko not_active IP Right Cessation
  • 2006-08-28 US US11/510,701 patent/US20070037071A1/en not_active Abandoned

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