Leica VB-6HR Lithography System Sales Specification TFE Source Version Document 963
Leica VB-6HR Lithography System Product Description Document 963 Leica Microsystems Lithography Ltd. Tel +44 1223 411123 Clifton Road, Cambridge. CB1-3QH Fax +44 1223 249678 United Kingdom eb-sales@leica.co.uk http://www.leica.com
Leica VB-6HR Sales Specification Abstract This document is the Sales Specification for the Leica VB-6HR Vectorbeam Series Lithography Tool. It is provided in confidence and should not be copied or its contents relayed to any third party without written permission. This document does not constitute an offer to provide a system which will meet these test requirements until confirmed as such by reference to this Specification Issue within a formal quotation from Leica Microsystems Lithography Limited. All reasonable steps have been taken to ensure that this publication is correct and complete, but should there doubt about any details, clarification may be sought from Leica Microsystems Lithography Ltd, or their accredited representative. The information in this document is subject to change without notice and should not be construed as a commitment by Leica Microsystems Lithography Ltd. Leica Microsystems Lithography Ltd accepts no responsibility for any errors that may appear in this document. Copyright Leica Microsystems Lithography Ltd, Cambridge, England, 1998 All rights reserved. The contents of this publication may not be reproduced in any form, or communicated to a third party without prior written permission of Leica Microsystems Lithography Ltd. Part Number: 963 V3-1 Date: January 1999 Version: 3.0 Issue: 1.0 Leica Microsystems Lithography Ltd. Tel: (+44) 1223 411123 Clifton Road, Cambridge. CB1 3QH Fax:(+44)1223249678 United Kingdom email:ebsales@leica.co.uk Part Number: 963/2_7.1
Table of Contents 1. INTRODUCTION 1 2. SYSTEM DESCRIPTION 1 2.1 System Configuration...2 2.2 Electron Optical Column Facilities...3 2.3 Electron Optical Control Systems...4 2.4 Stage and Holders...5 2.5 System Monitors and Control...6 2.6 Vacuum System...7 2.7 User Interface...8 2.8 Pattern preparation functions...9 3. SYSTEM SPECIFICATIONS 10 3.1 Workstage/Chamber...10 3.2 3.2 Substrate Handling...11 3.3 Electron Optics...12 3.4 Deflection system...14 3.5 Pattern Generator...15 3.6 Signal Processing...16 3.7 System Software...17 3.8 Pattern Preparation Options...19 3.9 Vacuum System...19 4. TARGET PERFORMANCE SUMMARY 20
Page 1 1. INTRODUCTION The Leica VB-6HR Vectorbeam series system is a high performance E-Beam lithography tool intended for nanolithographic high accuracy applications. This specification describes a variant of the tool configured with a thermal field emission source. The system uses the Gaussian beam, vector scan principle of pattern generation in combination with a step and expose stage strategy to cover large substrate areas. In addition it is provided with a wide degree of versatility in its operating modes enabling a unique range of applications to be economically performed. The system is provided with a comprehensive software control capability for both mask/reticle making and direct write on device substrates. Typical applications include: Research grade lithography for nanoelectronic and other high resolution structures. Direct writing in silicon prototyping/r&d, in III/V compound microwave semiconductor production/r&d and on other compatible substrate materials Reticle manufacture for UV stepper systems, X-ray lithography tools and other advanced mask technologies. Plus many more speciality tasks in electronics, optics and micromechanics. This new system retains many of the qualities developed in the earlier Leica Microsystems Lithography "Beamwriter" series tools. Experience gained from the supply of over 100 such systems has been used to define the new system specification. Retained features of the Beamwriter series products include: Console control remote from the clean room environment of the tool Substrate fixturing for both wafers and photoplates Industry favoured pattern preparation software Beam energy settings of 20/50/100keV Wide range of writing address grids and beam deflection field sizes Industry compatible networking and workstation control. Many new improvements have been introduced within the Leica VB6 Vectorbeam series range in general and to this system in particular, to extend operational facilities and improve performance for resolution, accuracy, throughput and ease of use. These include: A thermal field emission electron gun to increase beam current density and source lifetime. An intelligent vector scan pattern generator with rapid shape update, 25MHz beam deflection clock rate and grid step size selection to increase writing speed on less critical levels A six inch traverse stage with capacity to hold up to eight inch wafer substrates Single substrate loading facilities with optional 10 station autoloader Increased precision stage metrology to lambda/512 Distributed microprocessor sub-system control. Suite of diagnostic software to assist in servicing and achieve short MTTR timings
Page 2 2. SYSTEM DESCRIPTION 2.1 System Configuration The Leica VB-6HR system configuration consists of the following major subsystems: (a) (b) (c) (d) (e) (f) Plinth, Chamber, Loadlock with Vacuum system and automatic control. XY Stage and Control System Beam Forming electron optical column with beam formation control system Beam deflection system, pattern generator and pattern data handling system Operator interface and overall control software using workstation display/keyboard with distributed micro processor sub system controllers. Network connection to an off line job and pattern preparation workstation These are integrated into 6 main units: (a) (b) (c) (d) (e) (f) Column, Chamber with stage and loading mechanism, Plinth, Airlock and High Vacuum System; these must be mounted in a clean room area, free from vibration, magnetic fields and temperature changes. Two Column Electronic control racks (CER1 & CER2); These must be positioned within 0.5m of the column/plinth assembly either within, or adjacent to, the clean room. Two Electronic Racks; These contain the control system for beam formation, the digital electronics for pattern writing and linear power supplies. These should be mounted close to the CER racks but their actual placement is not critical. The Control Console; this is the operator interface and supports displays, the keyboard and mouse, main control CPU, disks and internal ETHERNET connections. This can be located at a convenient distance from the column and plinth assembly (several meters) EHT power supply providing the necessary electron source supplies in a safety interlocked enclosure. This should be located within 2m of the column within the clean room. Two racks, one containing vacuum ion pump supplies and the other for rotary mechanical pre-evacuation pumps. Further details of the size, weight and installation requirements for the system can be found in the Vectorbeam Series / Leica VB6 Pre-Installation Guide Part Number GL-878215.
Page 3 2.2 Electron Optical Column Facilities The beam forming electron optical column consists of an electron source, zoom condenser lenses and a compound objective lens. In addition there are electromagnetic alignment coils, a blanking plate assembly, beam deflection systems a dual quadrupole stigmator and an aperture array to select final beam convergence angle. The electron source is a Thermally assisted Field Emitter (TFE or Schottky emitter). The cathode is integrated within a source emitter module which includes suppressor, extractor and focus electrodes and is isolated from the anode ground potential by a high quality insulator assembly. This arrangement is designed to provide reliable operation up to 100kV acceleration potential. The cathode, suppressor, extractor and focus electrode assembly also form an electrostatic lens which relays the image of the TFE virtual source through the electromagnetic tilt and shift source alignment section. This electrostatic lens, in combination with a following electromagnetic condenser lens, is driven in a zoom arrangement to deliver an image of the source into the fixed plane of the blanking plate assembly which is conjugate with the substrate plane. This image of the source may be either magnified or demagnified compared to the TFE virtual source depending upon final beam diameter requirements. Blanking (rapid turn off) of the beam at the substrate is achieved by electrostatic deflection. The beam is deflected away from its axial path through the lower column region in order to stop it on an intermediate aperture. TFE Column Optics C1 - electrostatic gun lens Emitter Suppressor Extractor Focus Anode Gun alignment coils Tilt Shift C2 - magnetic lens Blanking cell Blanking aperture Spray aperture Upper main deflector Subfield deflector Lower main deflector C3 - magnetic lens Substrate Fast focus and stigmation elements Selectable aperture The objective lens is used to further demagnify the spot and deliver it to the writing plane. This lens is a compound lens consisting of an electromagnetic main lens with dual minor
Page 4 electromagnetic elements which can be rapidly driven in order to make dynamic refocusing corrections during beam deflection. Within this same region is a stigmator assembly consisting of a dual pair of electromagnetic quadrupoles. These are used to stigmate the axial beam for best circularity and to apply dynamic astigmatism corrections during beam deflection within the writing field. An aperture mechanism is located within the pole region of the objective lens which provides selection and alignment for up to six final beam defining apertures. This enables choice of the most optimum beam convergence angle to match application requirements and provides for more than one aperture of the most common sizes to extend operational running times between replacements. Within the backbore region of the objective lens is the beam deflection coil assembly which consists of a double lever pair of main coils used for precision placement of the beam and SEM mode scanning. A single lever minor deflector is situated between the main pair and is used for high speed scanning (sub-field deflection). 2.3 Electron Optical Control Systems Electron column control systems are used to establish the electron beam and maintain stability of the operating conditions. This includes electron gun run up, alignment of the gun and column, lens control to establish the required beam diameter and to focus/stigmate the beam at the exposure plane. A beam diameter measurement/control scheme is provided within the system. The deflection system can scan over a maximum field size of 1.024mm (at 20kV), but is also continuously adjustable down to 128µm square. The beam is positioned with 16 Bit precision within the selected field size, in addition the writing address grid can be changed in binary steps up to 32 times the basic (16 Bit) grid. An automatically calibrated deflection aberration correction scheme is used to correct scan non-linearity and to dynamically compensate deflection induced defocusing and astigmatism. This scheme yields a highly linear field with good linewidth control throughout, it also provides the versatility to select field size to optimise accuracy requirements whilst the address grid can be adjusted according to linewidth control and/or throughput requirements. The exposure rate (address grid clock rate) is variable from approximately 300Hz up to 25MHz. This enables a wide range of dose control to be applied to fully dose insensitive resists (without the need for retrace) and to vary the dosage of shapes within pattern file exposure for proximity effect compensation. A very wide range of dose levels may be assigned to individual shapes within a pattern file, assuring smooth dose compensation. Alternatively, up to 32 individually defined clocks may be set by the operator to facilitate dosage experimentation and evaluation. Experimental proximity effect compensation software can be provided within the pattern preparation software to define feature dosage. Other proximity effect correction software is available from third party vendors.
Page 5 2.4 Stage and Holders An X Y substrate stage is provided with a travel range of 153 x 165mm to enable exposure over the maximum allowable pattern area of supported substrates. This is monitored with a two axis helium neon laser interferometer positional measurement system. The measurement resolution of this system is lambda/512 yielding a least count of 1.2nm. Placement control uses both mechanical positioning of the stage, (using a stepper motor servo system), and continuous feedback of residual stage error to the beam deflection system. This beam error feedback (BEF) scheme dynamically tracks the stage position whilst settling after stage moves and compensates any drift in stage position during exposure. With a resolution of 1.2nm, minimal disturbance to pattern features is caused during pattern writing should residual stage position drift occur. Substrates are introduced onto the stage using an intermediate carrier (holder). This performs the function of rigidly supporting the substrate normal to the undeflected beam and parallel to the plane of the stage bearings. It is placed onto the stage by an automatic robot loading mechanism. All holders include a calibration target mark array which is co-planar with the substrate image surface. This multi-featured target is used in various system calibration procedures. Facilities are provided on the holders to ground the substrate (to remove exposure charge). Holders are available for all standard sizes of semiconductor wafers up to 8 inch diameter and photoplates of 6 inch square or 7.25 inch circular. In addition holders can be provided for custom requirements such as specific types of X-ray mask plates, wafer piece parts and rectangular chips or other types of non-standard substrates. The maximum writing area is 152mmx152mm. Other substrate sizes may be possible to customer order. Two (alternative) forms of load chamber are available, these are airlocked from the main chamber containing the X/Y stage and interferometer system. These have separate facilities for evacuation and dry nitrogen admittance. The single loader (standard system) enables single holders to be loaded as required, on to the stage or into two antechambers associated with the main chamber. These antechambers provide space for holder temperature stabilisation before writing. They enable a maximum of three substrates to be within the evacuated region at any one time. An optional multi-load airlock is available with a magazine loading capacity for up to ten individual holders. This is intended for fully automatic batch mode operation.
Page 6 2.5 System Monitors and Control Several signal transducer/processing sub-systems are provided within the machine for monitoring and controlling its operation. These include: Stage mounted beam current collection (Faraday cup) with amplification system to collect and measure the total exposure current in the beam. Back scattered electron (BSE) collector system consisting of four independent scintillator/light-pipe/photo multiplier chains. These may be individually switched into a summing matrix in order to enhance contrast for either dissimilar material or topographical features. The resulting video signal is digitised for use in all calibration and registration routines as well as providing a SEM mode display image. Transmission (TE) detector to measure the current profile of the beam, in conjunction with a knife edge target mounted on specific substrate holders. This is used for beam diameter assessment. Focal plane ( height ) detector using a solid state infra-red laser beam reflection scheme. This has a total focal plane range of ±100µm from nominal. It is used to drive compensations for the field size/rotation and focus errors which would otherwise occur when a substrate is non-planar or inclined. Temperature measurement transducers used to monitor the loading chamber, main stage and ambient temperature. These may be used for logging temperature stability within the system.
Page 7 2.6 Vacuum System The system has several independently valved and pumped volumes. The TFE electron gun emission chamber is pumped by two 45 l/s ion pumps with an additional 20 l/s ion pump below the anode. In order to establish the reliable ultra-high vacuum levels needed in the gun emission chamber, a bake out cycle is used which heats the gun structure for several hours. Subsequent cooling takes place with the eventual gun vacuum achieving a pressure in the region of 1 x 10-9 torr. The lower column volume and chamber are pumped by a 510 l/s turbomolecular pump. A 20 l/s ion pump is fitted to pump the blanking region of the column. The airlock is pumped by a separate 510 l/s turbomolecular pump. Pre-evacuation (rotary mechanical) pumps are used to reduce system pressure from atmosphere to the operational range of the turbo-molecular pumps. These in turn reduce system pressures to the operational range of the ion pumps which achieve the operational ultra-high vacuum state. Control of the pumps and associated valves and gauging is through a microprocessor based programmable controller interfaced to the overall system control. This comprehensive control scheme performs all system operational sequences including the start up from atmospheric pressure with an automatic bake out cycle when a new source is fitted. The control program for this (known as PICS ) also includes a number of safety interlocks to achieve safe operation of the system.
Page 8 2.7 User Interface The user interface is provided through workstation hardware running a comprehensive control program known as EMMA. This has been derived from the detail experience of the QPLUS and BEAMS programs used in the earlier Leica Beamwriter series machines. It retains many of the user proven features and facilities of these programs including: extensive range of machine instructions for pattern exposure, stage position measurement and placement control, registration, calibration, diagnostics, logging, etc. using command line input format. run time interpretation of pre-defined job control files for unattended operation. This avoids compilation delays, greatly aids de-bugging operations and provides the on line versatility to modify job sequences if and when needed. nesting and recall of user defined, commonly required job functions such as calibration procedures, custom logging requirements and error detection/correction procedures. EMMA operates under the VMS operating system, typically using a Digital Equipment Corporation workstation platform. This provides extensive facilities for both job and pattern file management as well as the support of a very wide range of peripheral devices. Pattern data files are typically prepared for exposure on a remote computer or workstation system and then transferred to this system using Ethernet protocol. EMMA itself communicates via a local Ethernet to the individual microprocessors which control the sub systems described in section 2.1 (a) to (f). Operation of the Leica VB-6HR system is performed at the remote console, this is provided with two separate display screens, a keyboard and mouse. Display 1 is part of the workstation control computer, this displays the EMMA control program sequences and all keyboard entries. It can also be used for job file preparation and pattern file preparation if required although it is recommended that these functions be performed on a remote system. Display 2 provides an SEM image capability when operating in the "SEM" mode. This provides a valuable diagnostic capability e.g. during direct write job set up. Although the system is provided with a wide range of manual control facilities, normal system operation is fully automatic, running from prepared job files. These are created off line using "application templates" with software assistance to create layouts and to define both exposure conditions and calibration/registration procedures. Pre-defined standard process conditions can be used to avoid the need for operators to possess detailed operational knowledge of the system.
Page 9 2.8 Pattern preparation functions Several pattern preparation options exist for the Vectorbeam series. The widely used computer aided transcription system, CATS, from Transcription Enterprises Ltd. is available for the system. It has many advanced functional features and capabilities which include pattern graphical display, manipulative functions for sizing, feature bias, rotation, mirroring, tonal inversion, window/blanking and logical operations on files. A number of industry favoured pattern file formats are supported. CATS further supports the use of the Proxecco proximity effect compensation software. Alternatively the pattern processing software package CAPROX is available from the Sigma C company. This also provides compatibility for various input formats and many advanced manipulative features for pattern display and modification including proximity effect compensation. It maintains a high level of hierarchical pattern definition from the CAD database in order to achieve file compression, reduce proximity effect compensation processing time and reduce file transfer times. These programs are normally supplied to operate on users existing workstation facilities, both support a wide range of hardware and operating system software options. ASSIGNMENTS Vectorbeam, Beamwriter, QPLUS, BEAMS and EMMA are trademarks of Leica DEC and VMS are trademarks of Digital Equipment Corporation CATS is a trademark of Transcription Enterprises Ltd. CAPROX is a trademark of Sigma C GmbH.
Page 10 3. SYSTEM SPECIFICATIONS 3.1 Workstage/Chamber Traverse distance Orthogonality error Drive method Prime mover Max m velocity Step response Positional measurement interferometer Measurement resolution Measurement arrangement Beam correction (BEF) range Thermal control x = 153mm y = 165mm <5µR (software corrected) Direct coupled rack and pinion Stepper motors x >10mm/s y >5mm/s 400µm x step in 250ms 400µm y step in 500ms Dual frequency laser 1.2nm (lambda/512) 2 axis system ±20µm Water circulator/stabiliser units Airlock standard Straight-through system for robotic loading includes 2 side ante-chamber storage stations optional 10 holder magazine batch loading system Holder Capacity standard 1 on the stage (within the main chamber), up to 2 held in storage stations. Operator selection of the loading cycle optional Up to10 in an automated airlock for batch mode operation. Transfer cycle Pump down time <2 min <15 min for standard airlock
Page 11 3.2 Substrate Handling Fixturing Maximum patterning area Holder sizes (standard and 10 holder airlock version) Carrier method referred to as a "holder" 152mm x 152mm Photoplates: 4, 5 & 6 square (other sizes to special order) Thickness: Max 90 mil for mask blanks up to 5, max 250 mil for 6 blanks X-ray blanks 3" or 4", thickness up to 10mm available to special order Wafers: SEMI standard 3, 4, 5 6 & 8 Each holder is provided with rotation pre-adjustment mechanism (Other sizes to special order). Wafers up to 8" can be loaded via the airlocks with substrate access restricted to a maximum area of 6" x 6". Calibration targets Mounted on the holder co-planar with the substrate. Used for system calibration, focus and stigmation control. Knife edge target provided for beam diameter assessment on selected holders. Holder mounting jig Alignment microscope Provided to simplify insertion of substrates. Optional microscope with X/Y table for prealignment of wafers within the holder prior to direct writing. This unit includes digital position displays to accurately identify base wafer co-ordinates in support of direct write job layouts.
Page 12 3.3 Electron Optics Gun Type Cathode life Beam current density @ 50kV Condenser Zoom lenses Thermal Field Emission (TFE) Zirconiated tungsten cathode. Typically >4000 hr Typically >1000A/cm² C 1 Electrostatic (within the gun electrode assembly) C 2 Electromagnetic Objective Lens Beam energy range Stigmation Blanking Typical measured spot size @ 100keV Beam current range C 3 Electromagnetic 20, 50 and 100keV calibrated conditions 8 pole Electromagnetic Electrostatic (located at the C 2 conjugate image plane) 8nm to 150nm Typically 100pA to 200nA. Final Aperture Size (µm) Theoretical Predicted Beam energy Spot size Spot Diameter Range 20keV 15nm - 200nm (full width half maximum) 50keV 6nm - 150nm 100keV 5nm - 100nm Detailed Theoretical predictions: 20keV Spot Beam Current size currentdensity (nm) (na) (A/cm²) 50keV Spot Beam Current size current density (nm) (na) (A/cm²) 100keV Spot Beam Current size current density (nm) (na) (A/cm²) 200 15 0.2 88 6 0.3 830 5 0.5 2000 400 25 2.3 370 10 2.5 2600 10 8.0 9400 800 100 80.0 800 - - - - - -
Page 13 Predicted Theoretical Deflection Performance: For 20keV: Minimum spot size (nm) for 20% maximum spot size variation across deflection field at maximum brightness: Final Deflection field size (µm) Aperture 1000 500 250 125 (µm) 800 270 135 75 75 600 160 80 40 40 400 90 45 26 25 200 65 25 15 15 For 50keV: Minimum spot size (nm) for 20% maximum spot size variation across deflection field at maximum brightness: Final Deflection field size (µm) Aperture 800 400 200 100 (µm) 800 270 135 75 75 600 120 60 30 30 400 55 30 12 10 200 24 10 6 6 For 100keV: Minimum spot size (nm) for 20% maximum spot size variation across deflection field at maximum brightness: Final Deflection field size (µm) Aperture 560 400 200 100 (µm) 800 145 105 70 70 600 80 60 30 30 400 40 20 12 10 200 12 10 5 5 System Performance Beam current drift Beam positional stability Column set up Beam defining apertures <1%/hr <150nm/hr Automatic- microprocessor controlled Manual adjustment also provided 6 selectable by aperture changer mechanism. Note Optionally the Leica VB-6HR may be provided for operation up to a maximum beam energy of 50keV. In such situations all specifications quoted herein for performance above 50keV are not applicable.
Page 14 3.4 Deflection system SEM Mode Magnification Up to 200K times Pattern Generation Main Field Deflection Field size range Address grid range field size and step increment Sub-field Deflection Sub-field Size Compensations applied focus and rotation errors. Pre-final lens 128µm - 1024µm @ 20keV 128µm - 800µm @ 50keV 128µm - 560µm @ 100keV 2nm - 500nm according to selected Pre-final lens 1/64 of calibrated field size Automatic calibration for: a) Field linearisation b) Stage position errors, x,y c) Deflection defocusing d) Deflection astigmatism e) Substrate height induced field size, Maximum field rotation range ±1 for re-registration alignments
Page 15 3.5 Pattern Generator Type Shape repertoire Shape placement grid Writing address grid High speed (sub-field) scan range Beam deflection rate Dose control Vector scan Any trapezoid, triangle or rectangle with beam scanning aligned to the X deflection axes. Rectangles may be scan aligned to X or Y axis. 1/65536 of the calibrated field size (16 bit resolution) Steps selectable in binary increments, (e.g. 1, 2, 4, 8, 16 & 32) of the placement grid. 1/64 calibrated field size Variable from 300Hz to 25MHz 256 levels (including 32 operator selectable dose levels for manual assignment) Pattern buffering Buffered shape server to typically deliver 60000 shapes/sec (dependent on pattern nature and complexity).
Page 16 3.6 Signal Processing Backscattered electrons: SEM display facilities Beam measurement: Current Diameter Height Mapping: Type Focal plane range Resolution Compensations applied Temperature Backscattered electron (BSE) detector comprising four scintillators with individual light pipe couplings to four photomultipliers. BSE display with TV rate to TV/512 scanning, µ-mark & data graphics, line scan mode, reduced raster, etc. Collection "Faraday" cup, amplifier and digitisation electronics interfaced to the control system Knife edge scan technique with special holder mounted target edge positioned above an electron detector mounted on the stage table. Optical Transducer using reflective infra-red laser ranging ± 100µm from nominal < 0.05µm Beam deflection field size and rotation Focal plane to maintain best focus Precision sensors for airlock, main stage and ambient temperatures, interfaced to the control computer system for monitoring purposes.
Page 17 3.7 System Software Vectorbeam Control Program User Interface "EMMA" comprehensive command line interpreter for all system instructions. EMMA typically executes on a DEC workstation or equivalent hardware under the VMS operating system providing support to a wide range of standard peripheral devices. EMMA Facilities: System Instructions Job Control Deflection Calibration/ Compensation Column Automation Height Correction Co-ordinate Mode Generation Alignment and Registration Metrology VMS Interface Comprehensive control facilities are provided for all major automated subsystems including stage movement, beam formation, deflection, pattern generation, monitoring and logging. Additionally extensive use is made of stored parameters such as identifiers for frequently used stage positions, deflection field compensation sets, EO column set up, etc. Fully automatic run time interpretation and execution of stored job files. These are typically created by direct keyboard entry using the EDIT editor of the workstation. No further compilation of the control file is necessary. Fully automatic procedures for calibrating deflection field size and rotation, dynamic compensation of linearity distortion, defocus and astigmatism. Calibration commands for periodic drift correction and subsidiary shift and beam error feedback systems. Store and recall of standard field size set ups. These facilities provide field size agility using stored calibration data recall in less than 60 sec following field size changes. Fully automatic electron gun run up and beam formation, setting beam diameter/current, focus and stigmation. Periodic beam current drift measurement and exposure dose compensation. Automatic measurement of substrate height variations to compensate both field size/rotation and beam focus for substrate inclination and non-flatness. Matching to other lithographic tool co-ordinate systems in mix and match E-Beam lithography schemes. Wide range of mark detection and location algorithms for direct write and phase shift mask applications using both material (atomic number) contrast and topographical contrast on a variety of mark shapes and sizes. Multimode direct write alignment and registration techniques are available from simple global alignment to full die by die registration. Measurement of x/y feature location on compatible substrates. Typically used to pre-measure optically produced layers in order to plan the most appropriate E- Beam registration strategy. It is particularly valuable where run out exists between the optical and E-Beam tools. For direct job interaction with the operating system. This provides a range of facilities including deleting/reworking
Page 18 of files (housekeeping), recall of stored operating parameters, timing function (SHOW TIME) and initiating user defined utilities. Error Handling EMMA contains an "on error" escape mechanism in order to recover many situations where system response to job instructions is not as anticipated. When such an error condition occurs, a user defined error recovery procedure can be initiated automatically. Logging Vacuum Control Diagnostics This provides the ability to store and/or print many useful job related outputs from the system during operation. Typically used in "job accounting" for later referral, it can provide data on date, time, calibration accuracies, beam diameter/current, drift compensation, system error status and recovery etc. The vacuum system is automatically sequenced by microprocessor control. A high integrity control program PICS (with hardware and software interlocks) controls all vacuum sequences ensuring simple push button Air/Vacuum selection for the gun, column, chamber and airlock. A high degree of automatic fail-safe and/or auto recovery from power fail ensures safe, reliable operation. The vacuum control system also controls an auto gun bake out procedure for the establishment of the high operational vacuum level in the gun emission chamber. A range of machine and subsystem diagnostic test programs is available for service engineer testing during maintenance. These assist in rapidly determining any error conditions in the interfaced hardware to reduce system downtime to a minimum The use of diagnostics is not formally supported for customer use except where a separate training agreement has been made. Further description of the EMMA System Software release can be found in the relevant Software Product Description documents.
Page 19 3.8 Pattern Preparation Options a) CATS by Transcription Graphics based pattern manipulation & Enterprises Ltd transcription software with Proxecco proximity correction b) CAPROX by Sigma C Pattern manipulation and transcription software which maintains input file hierarchy to maximise file compression with proximity correction. Further details of these third party vendor products are available on request. 3.9 Vacuum System Electron gun/anode region Blanker region Main chamber/lower column Airlock Backing Control Two 45 l/s ion pumps One 20 l/s ion pump One 20 l/s ion pump 510 l/s Turbo pump 510 l/s Turbo pump Two 16m³/hr pre-vacuum pump Micro-processor based controller
Page 20 4. TARGET PERFORMANCE SUMMARY Stitching accuracy (mean + 3 sigma) Overlay accuracy (mean + 3 sigma) <40nm for 500µm main field @ 100keV <60nm for 800µm main field @ 50keV <70nm for 1000µm main field @ 20keV <40nm for 500µm main field @ 100keV <50nm for 800µm main field @ 50keV <50nm for 1000µm main field @ 20keV Min feature size Field Beam Min Max linewidth (in 100nm thick size energy linewidth variation PMMA resist) (µm) (kev) (nm) (%) 100 100 30 ±20 100 50 35 ±20 500 20 140 ±20 1000 20 180 ±15 Full details describing how the above (and other ) performance parameters are demonstrated as part of the system acceptance protocol are shown in document reference 956 available on request.