Details of a Researcher - Beaucamp, Anthony

© 2014 Optical Society of America. The progressive transition from Excimer to extreme ultraviolet (EUV) lithography is driving a need for flatter and smoother photomask blanks. It is, however, proving difficult to meet the next-generation specification with the conventional chemical mechanical polishing technology commonly used for finishing photomask blanks. This paper reports on the application of subaperture computer numerical control precessed bonnet polishing technology to the corrective finishing of photomask substrates for EUV lithography. Full-factorial analysis was used to identify process parameters capable of delivering microroughness below 0.5 nm rms while retaining relatively high removal rates. Experimental results show that masks prepolished to 300-600 nm peak-to-valley (P-V) flatness by chemical/mechanical polishing can then be improved down to 50-100 nm P-V flatness using the automated technology described in this paper. A series of edge polishing experiments also hints at the possibility of increasing the quality area beyond the 142 mm square defined in the official EUV photomask specification.

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D04 Development of CAM system for new drill shape creation

KAWAI Kimio, BEAUCAMP Anthony, IMAIZUMI Noriyuki, SAKURAI Masatoshi, TAKEUCHI Yoshimi

The ... Manufacturing & Machine Tool Conference (The Japan Society of Mechanical Engineers) 2014 ( 10 ) 207 - 208 2014.01

Accepted

It is strongly requested to develop a new CAM system to shorten the drill fabrication time, to reduce material costs, and to create a new drill configuration by predicting its characteristics. Current drill shape prediction system cannot necessarily treat drill cross-section shape including the cutting edge, groove and so on, mathematically. The system becomes practical if these drill specification is mathematically formulated. The study reports the development of a system to predict not only cross-section shape but also various parameters from grinding wheel data of drill making.

Fabrication of parabolic wolter type-I molding die with 100 nm form accuracy

Anthony Beaucamp, Yoshiharu Namba, Richard Freeman

Proceedings - ASPE/ASPEN Summer Topical Meeting: Manufacture and Metrology of Freeform and Off-Axis Aspheric Surfaces 9 - 12 2014

Accepted

Technological advances in super fine finishing

Beaucamp A.T.H., Namba Y.

Conference Proceedings - 14th International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2014 1 21 - 39 2014

Focusing short wavelength radiations such as Extreme Ultra-Violet (EUV) and X-rays can be accomplished by assemblies of reflective aspheric optics. Application of such systems ranges from research in X-ray astronomy and microscopy, to semiconductors production by EUV lithography. But such optical surfaces require finishing to very low levels of micro-roughness, in proportion to the wavelength of incoming radiation. In this paper, recent advances in super fine finishing technologies (capable of achieving micro-roughness below 0.5 nm rms) for aspheric and freeform optical surfaces are presented. The paper deals with both ultra-precision grinding and polishing technologies, with the performance and advantages/disadvantages of each method being discussed, and examples of applications provided.

Surface integrity of fluid jet polished tungsten carbide

Anthony Beaucamp, Yoshiharu Namba, Wilhelmus Messelink, David Walker, Phillip Charlton, Richard Freeman

Procedia CIRP 13 377 - 381 2014

Accepted

In recent years, Fluid Jet Polishing (FJP) has been studied for its potential as a finishing method on optical lenses, mirrors and molds for a number of materials, such a glass and nickel. In this paper, the surface integrity of binderless tungsten carbide after polishing by FJP was studied experimentally. Two aspects in particular were focused on: (1) identifying process conditions under which grain boundaries may dislocate (thus leading to unintentional loss of grains from the substrate) and (2) identify process conditions under which abrasive particles may become embedded into the substrate, in order to prevent surface contamination. © 2014 The Authors. Published by Elsevier B.V.

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Shape adaptive grinding of CVD silicon carbide

Anthony Beaucamp, Yoshiharu Namba, Herman Combrinck, Phillip Charlton, Richard Freeman

CIRP Annals - Manufacturing Technology 63 ( 1 ) 317 - 320 2014

Accepted, ISSN 00078506

Because of the direct relationship between removal rate and surface roughness in conventional grinding, ultra-precision finishing of hard coatings produced by chemical vapour deposition (CVD) usually involves several process steps with fixed and loose abrasives. In this paper, an innovative shape adaptive grinding (SAG) tool is introduced that allows finishing of CVD silicon carbide with roughness below 0.4 nm Ra and high removal rates up-to 100 mm 3/min. The SAG tool elastically complies with freeform surfaces, while rigidity at small scales allows grinding to occur. Since material removal is time dependent, this process can improve form error iteratively through feed moderation. © 2014 CIRP.

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Shape Adaptive Grinding (SAG): A Novel Fabrication Method for Freeform Optical Molds

Anthony Beaucamp and Yoshiharu Namba

Classical Optics 2014 ($\lbrace$OSA$\rbrace$) 2014

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Manufacture of aspherical molding dies for x-ray telescopes after ASTRO-H

Yoshiharu Namba, Anthony Beaucamp, Hironori Matsumoto, Keisuke Tamura, Yuzuru Tawara, Hideyo Kunieda, Tadayuki Takahashi

Proceedings of SPIE - The International Society for Optical Engineering 9144 2014

Accepted, ISSN 0277786X

© 2014 SPIE. Producing X-ray imaging space telescopes is a very expensive endeavor, due in great part to the difficulty of fabricating thin mirrors for Wolter type-I optical assemblies. To meet this challenge, replication from optical molding dies (also called mandrels) has become the preferred method, as it is reliable and economical. Several replication methods exist: in the case of the ASTRO-H mission, DC magnetron sputtering was used to deposit Pt/C multilayer coating on glass molding dies. The multilayer coating was then bonded with epoxy to aluminum shells and then separated from the die. Another mirror replication method consists of slumping thin glass sheets over a full (or a section of) revolution molding die under high temperature. This method was demonstrated in the case of the NuSTAR mission. But the challenge of fabricating truly aspheric Wolter type molding dies, which are capable of highly accurate angular resolution (below 5 arcs), remains very expensive and time consuming. In this paper, three methods for producing X-ray optic molding dies are presented. Each method uses a different substrate material and process chain, as follows: electroless nickel plated aluminum (first diamond turned then correctively polished), fused silica (first precision ground then correctively polished), and CVD silicon carbide (which can be finished entirely with a newly developed Shape Adaptive Grinding process). The process chains employed for each method are explained in details, and their relative merits discussed. A way forward for the next generation of X-ray telescopes after ASTRO-H is then drawn out.

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Interactions between manufacture and measurement of off-axis aspheres

David D. Walker, Anthony Beaucamp, Matt Bibby, Tony Fox-Leonard, Caroline Gray, Christopher King, Paul Rees, Guoyu Yu

Proceedings - ASPE/ASPEN Summer Topical Meeting: Manufacture and Metrology of Freeform and Off-Axis Aspheric Surfaces 72 - 77 2014

Accepted

High Energy Fluid Jet Machining (HEFJet-Mach): From scientific and technological advances to niche industrial applications

D. A. Axinte, B. Karpuschewski, M. C. Kong, A. T. Beaucamp, S. Anwar, D. Miller, M. Petzel

CIRP Annals - Manufacturing Technology 63 ( 2 ) 751 - 771 2014

Accepted, ISSN 00078506

With the increasing demands to generate complex parts on ever-more advanced, but difficult-to-cut materials, a group of technologies, generically called High Energy Fluid Jet Machining (HEFJet-Mach) has found niche applications that stimulated further development of science and technology in this field. Here HEFJet-Mach refers to unrestrained fluid jets used to remove and/or deform the workpiece material. The aim of this paper is to systematically present the recent developments of HEFJet-Mach from various perspectives: machine/system designs; modelling of both jet plumes and their interactions with the target surfaces; part quality including material integrity; supervision and control of the process; key aspects of machine maintenance and health and safety. © 2014 CIRP.

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Finishing of electron beam melted titanium (Ti6Al4V) using shape adaptive grinding tools

Anthony T. Beaucamp, Yoshiharu Namba, Phillip Charlton, Arthur A. Graziano

Proceedings - ASPE 2014 Spring Topical Meeting: Dimensional Accuracy and Surface Finish in Additive Manufacturing 62 - 65 2014

Accepted

Finishing of EUV photomask substrates by CNC precessed bonnet polisher

Anthony T.H. Beaucamp, Yoshiharu Namba, Phillip Charlton, Richard R. Freeman

Proceedings of SPIE - The International Society for Optical Engineering 8880 2013.12

Accepted, ISSN 0277786X

The progressive transition from Excimer to EUV lithography is driving a need for flatter and smoother photomasks. It is proving difficult to meet this next generation specification with the conventional chemical mechanical polishing technology commonly used for finishing photomasks. This paper reports on the application of sub-aperture CNC precessed bonnet polishing technology to the corrective finishing of photomask substrates for EUV lithography. Fullfactorial analysis was used to identify process parameters capable of delivering 0.5 nm rms surface roughness whilst achieving removal rates above 0.1 mm3/min. Experimental results show that masks pre-polished to 300~600 nm P-V flatness by CMP can then be improved down to 50~100 nm P-V flatness using the automated technology described in this paper. A series of edge polishing experiments also hints at the possibility of increasing the quality area beyond the 5 mm defined in the official EUV photomask specification. © 2013 SPIE.

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Development of hybrid "fluid jet / float" polishing process

Anthony T.H. Beaucamp, Yoshiharu Namba, Richard R. Freeman

Proceedings of SPIE - The International Society for Optical Engineering 8838 2013.11

Accepted, ISSN 0277786X

On one hand, the "float polishing" process consists of a tin lap having many concentric grooves, cut from a flat by single point diamond turning. This lap is rotated above a hydrostatic bearing spindle of high rigidity, damping and rotational accuracy. The optical surface thus floats above a thin layer of abrasive particles. But whilst surface texture can be smoothed to ~0.1nm rms (as measured by atomic force microscopy), this process can only be used on flat surfaces. On the other hand, the CNC "fluid jet polishing" process consists of pumping a mixture of water and abrasive particles to a converging nozzle, thus generating a polishing spot that can be moved along a tool path with tight track spacing. But whilst tool path feed can be moderated to ultra-precisely correct form error on freeform optical surfaces, surface finish improvement is generally limited to ~1.5nm rms (with fine abrasives). This paper reports on the development of a novel finishing method, that combines the advantages of "fluid jet polishing" (i.e. freeform corrective capability) with "float polishing" (i.e. super-smooth surface finish of 0.1nm rms or less). To come up with this new "hybrid" method, computational fluid dynamic modeling of both processes in COMSOL is being used to characterize abrasion conditions and adapt the process parameters of experimental fluid jet polishing equipment, including: (1) geometrical shape of nozzle, (2) position relative to the surface, (3) control of inlet pressure. This new process is aimed at finishing of next generation X-Ray / Gamma Ray focusing optics. © 2013 SPIE.

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Super-smooth finishing of diamond turned hard X-ray molding dies by combined fluid jet and bonnet polishing

Anthony Beaucamp, Yoshiharu Namba

CIRP Annals - Manufacturing Technology 62 ( 1 ) 315 - 318 2013.04

Accepted, ISSN 00078506

Fabricating super-smooth aspheric optics for future hard X-ray telescopes will require a new process chain. Whilst diamond turning of electroless nickel plating can generate ~100 nm P-V aspheric molding dies, associated turning marks must be removed before replication. An innovative two-step freeform finishing method is presented, that combines fluid jet and precessed bonnet polishing on a common 7-axis CNC platform. The removal rate and surface texture relationship of fluid jet with abrasive type and pressure is documented, and form correction demonstrated down to 27 nm P-V. A novel bonnet tool-pathing method called "continuous precessing" is then applied, which delivers super-smooth anisotropic surface texture of 0.28 nm rms. © 2013 CIRP.

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Edge control in CNC polishing, paper 2: Simulation and validation of tool influence functions on edges

Hongyu Li, David Walker, Guoyu Yu, Andrew Sayle, Wilhelmus Messelink, Rob Evans, Anthony Beaucamp

Optics Express 21 ( 1 ) 370 - 381 2013.01

Accepted

Edge mis-figure is regarded as one of the most difficult technical issues for manufacturing the segments of extremely large telescopes, which can dominate key aspects of performance. A novel edge-control technique has been developed, based on 'Precessions' polishing technique and for which accurate and stable edge tool influence functions (TIFs) are crucial. In the first paper in this series [D. Walker Opt. Express 20, 19787-19798 (2012)], multiple parameters were experimentally optimized using an extended set of experiments. The first purpose of this new work is to 'short circuit' this procedure through modeling. This also gives the prospect of optimizing local (as distinct from global) polishing for edge mis-figure, now under separate development. This paper presents a model that can predict edge TIFs based on surface-speed profiles and pressure distributions over the polishing spot at the edge of the part, the latter calculated by finite element analysis and verified by direct force measurement. This paper also presents a hybrid-measurement method for edge TIFs to verify the simulation results. Experimental and simulation results show good agreement.©2013 Optical Society of America.

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Ultra-Precision Machining of Aspheric Molds for Next Generation X-Ray Telescopes

Namba Yoshiharu, Beaucamp Anthony

Proceedings of JSPE Semestrial Meeting (The Japan Society for Precision Engineering) 2013 239 - 240 2013.01

Accepted

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