International Business Machines Corporation

Other

John George Hartley

Rodney A Kendall

Maris A Sturans

William A Enichen

Timothy R Groves

Rainer Butsch

Michael S Gordon

Gregory J Dick

Abigail S Ganong

John W Pavick

Henry Ignatius Smith

Werner Stickel

James D Rockrohr

David J Pinckney

Mark L Schattenburg

James Gregory Goodberlet

Joseph B Frei

Michael Stuart Gordon

Richard Rieland

Denise M Puisto

Juan Ferrera

Ken Tze-Kin Chan

Eileen V Clarke

Mark K Mondol

Fine positioning of a shaped or patterned charged particle beam without use of intrusive fiducial marks is achieved by providing a dithered shadow pattern, preferably in the form of a grid, within the shaped or patterned charged particle beam. Light output from fiducial marks preferably formed of a scintillating material is reduced when the dithered shadow pattern is incident on some or all of the fiducial marks. The timing of the incidence of the shadow pattern on fiducial marks indicates the position of the shaped or patterned charged particle beam such that correction of the beam position on the target can be corrected to a small fraction of system resolution. The dither pattern and repetition period is chosen to avoid interference with uniformity of beam illumination of the target. Feedback of position error thus provides phase locked position correction in real time and is suitable for mask making since the fiducial marks are not intrusive.

Spatial phase locking with shaped electron beam lithography

A system for supporting and adjusting the position of an object in a vacuum includes inner and outer support rings that are connected by flexible mounts that are compliant along one axis and stiff along other axes, and drivers extending through the wall of the vacuum chamber that move the supports independently along their respective axes. At least the inner support is clamped after adjustment by a clamp that exerts a strong clamping pressure while exerting transverse force only less than a threshold selected to avoid motion after adjustment.

Electron beam position reference system

A multi-beam shaped-beam electron beam lithography system employs conventional lenses and magnetic deflectors, with an array of lithographically fabricated electrodes disposed about a central axis to simultaneously and independently deflect electron beams in beamlet exposure ranges separated transversely from one another within a subfield, so that subfields overlap.

Multi-beam shaped beam lithography system

Motion of a block carrying a grid for backscattering portions of a pattern of charged particles incident on the grid is moved generally axially of a charged particle beam tool while the position of the block is measured, preferably to optically, with a grazing incidence laser beam or interferometer, in the axial direction for any or all of the degrees of freedom of the block. Backscatter is correlated with known grid position to correct the backscatter measurement to compensate for lateral components of motion parallel to the target plane in measurement of actual beam position at different axial locations. Telecentricity and landing angle can thus be observed to an accuracy of 0.003 milliradians in substantially real time; permitting substantially real time adjustment thereof. The basic principles of this process and apparatus can be extended to measurement of numerical aperture and are equally applicable to probe-forming and beam projection lithography tools.

Accurate real-time landing angle and telecentricity measurement in lithographic systems

An e-beam lithographic system capable of in situ registration. The system has an optics section such as a VAIL lens. A controllable stage moves a substrate with respect to the beam axis to place substrate writing fields beneath the beam. A field locking target between the optics section and the stage has an aperture sized to permit the beam to write a target field on the substrate. The field locking target includes alignment or registration marks around the aperture. A differential interferometric system measures the relative positions of the field locking target and the stage and controls stage position. The beam patterns the substrate on a field by field basis. As the stage is moving into position for each field, the beam is swept until it hits the alignment marks, thereby checking system alignment. The beam control data, i.e., coil currents necessary to hit the marks are stored, and drift correction values calculated from the beam control data. Meanwhile, pattern beam control is compensated by the drift correction values.

Target locking system for electron beam lithography

A scattering target for use in a particle beam system is formed from a grid of gold on a substrate of carbon, with an intermediate smoothing layer (e.g. copper) on the carbon to provide a surface sufficiently smooth to provide an adequate target. An optional bonding layer may be used to improve adhesion between the gold and the smoothing layer.

Calibration target for electron beams

A method of calibrating an electron beam system in which a plurality of standard grids are mounted in various presentations in the electron beam system and treated as different presentations of the same grid for the purposes of applying algorithms to adjust a computer-controlled system for deflecting the electron beam. A standard grid mask is fabricated in an electron beam system and used in a stepper to make the standard grids, the same stepper and the same stepper optics being used to make each of the standard grids.

Method of calibrating an electron beam system for lithography

An e-beam system for making masks corrects the beam for pattern-dependent errors by executing the bulk of the post-processing program only once, with two sets of output data being generated by the encode routine. A first output file of the encode routine generates the beam control data without pattern-dependent corrections. A second output file merges the beam control data with the data for metrology marks. A test wafer is patterned using the second output file and measured to generate a set of pattern correction data. Production wafers are written using the beam control data corrected on the fly by the pattern correction data.

Correction of pattern-dependent errors in a particle beam lithography system

A system and method of converting large Integrated Circuit (IC) designs into patterns. First, based on shape density, the design is fragmented into pieces, each piece including roughly the same number of shapes. Next, a band of shapes, all within the proximity correction area for each piece, are identified. Each piece, including its identified band, is processed individually to convert data within the piece and within the proximity correction band to Numerical Control (NC) data. The NC data for the proximity correction band is discarded. The piece's NC data is stored as an NC data file for the piece. This is repeated until all of the pieces are converted to NC data. Finally, the pattern is written, one piece at a time.

Piece-wise processing of very large semiconductor designs

The invention relates to the field of electron beam lithography. More particularly, the invention relates to shaped beam lithography for generating variable-shaped spots on photoresist for use in integrated circuit manufacturing processes. According to an aspect of the invention, an electron beam lithography method is provided, having the steps of generating an electron beam and directing it through a first square aperture in a first lamina, the first square aperture having a first serrated edge. According to a further aspect of the invention, the beam emanating from the first square aperture in the first lamina is focused onto a second square aperture in a second lamina having a second serrated edge. The spot generated has a subresolution edge zone induced at least in part by the first serrated edge and/or the second serrated edge.

Spot-to-spot stitching in electron beam lithography utilizing square

Across chip line width variations and other repetitive deviations from the design pattern desired in E-Beam lithography are compensated for by examining each of the regions (i.e., frames, stripes, etc.) of a patterned substrate, determining the amount of deviation for each region, and using the determined regional deviation as a local bias when patterning subsequent substrates. Thus, the E-Beam lithography tool will utilize both global and local biases in order to produce new patterned substrates which lack the deviations found when local bias was not applied. In this way, the root cause of the deviation does not need to be determined. The local bias can be applied directly by modifying the E-Beam lithography system tool commands to provide for patterning wider or thinner lines or to provide for greater or lesser exposure time. Alternatively, the local bias can be applied by varying the emission current of the electron gun for different regions of the substrate.

Emulation methodology for critical dimension control in E-Beam

Process steps are provided to analyze image placement on a pre-distorted lithographic mask produced by a lithographic system. Obtain metrology data, form a reference array equal to the design coordinates of the metrology sites. Align the metrology data grid coordinate system to remove rigid body components from the metrology data offsets. Parse the metrology data into one or more correction areas. If the mask is to have its disposition provided according to the statistics of the residual errors in the correction areas, then compute the statistics and compare them to the specifications. Otherwise concatenate the local reference arrays summed with their corresponding correction area center coordinates to form reference mark design location arrays. Concatenate temporary arrays with the mask offsets free of pre-distortion into an array of mask offsets corresponding to desired disposition areas and compute statistical distribution of residual errors in array(s) of mask offsets for disposition. Compare statistical distribution of residual errors determined during computation with the specified statistical distribution of the mask disposition areas to accept or reject the mask.

System and method for evaluating image placement on pre-distorted masks

A method for monitoring resist charging in an electron beam lithography system is disclosed. The method involves the use of a reference plate (REFP) registration scheme in which a resist-coated REFP having registration marks on a substrate is prepared and scanned. The scanning process includes the deposition of an amount of charge on the surface. Then the REFP is coated with a resist to be tested and scanned again. The difference between the two scans is calculated. Preferably, each scan is performed first with the stage moving in a forward-ordered serpentine path in the tool to determine the perceived positions of the registration marks and then in a backward-ordered serpentine path. As the tool's stage moves from field to field, a small charge is deposited on the REFP to simulate the effect of a writing process. The difference between the forward and reverse scan position measurements is then determined. As any intrinsic positional errors in measurement will cancel out, the forward/backward error provides a monitor of the magnitude of resist charging.

Method for monitoring resist charging in a charged particle system

A digitally stepped deflection raster system and a method of operation thereof are disclosed. The digitally stepped deflection raster system operates to provide horizontal and vertical scans of an area of interest. The total length of each of the horizontal and vertical scans is proportioned into segments to provide non-continuous scanning signals that are arranged into predetermined raster patterns each of which reduces the deflection placement error of the digitally stepped deflection raster system.

Digitally stepped deflection raster system and method of use thereof

A method is disclosed for improving the electron beam apparatus lithography process wherein the calibration procedure for the apparatus is improved by using the product pattern and stepping sequence used to make the mask on a calibration plate and/or calibration grid and to determine improved apparatus correction errors which errors are used to control the apparatus for making an improved mask. The well-known EMULATION procedure is improved by calculating additional field correction errors based on a two step registration procedure to determine X/Y apparatus stepping errors. The LEARN procedure based on a static calibration grid procedure is improved by employing the duty cycle of the product pattern to calibrate the apparatus to determine deflection beam errors.

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Fishkill, NY, United States of America

John George Hartley