For multi-purpose applications such as advanced LSIs, photonics, MEMS, and other nano- fabrications, it is important
for electron beam (EB) writers that handle the various substrates with their own single mechanical platform. We have
been developing the adjusting pallet function both 200mm and 300mm bases to satisfy this requirement. By analyzing
actual examples of adjusting pallets we proved their effectiveness to their applications. The combination of adjusting
pallet function, 1Xnm resolution column and character projection technologies will enable the next generation EB writer
“F7000” to fit from Fab to Lab applications.
The authors designed novel electron beam slim column cells that have the outer diameters of 60mm and 40mm in width
for an e-beam exposure of patterns down to 12nm and below. The column has maximum magnetic flux density of less
than 2.2Tesla in the pole-piece of objective lens. No magnetic saturation occurs in the lens. The 12-88% blur at shaped
beam edges through the column is better than 12nm to expose 12nm 1:1 LS patterns. Calorific power by lens coil of the column is smaller than 200watt. This slim column cell of high resolution and small size will provide various types of
electron beam exposure systems with single or multiple exposure columns.
Character projection (CP) exposure has some advantages compared with variable shaped beam (VSB) system; (1) shot count reduction by printing complex patterns in one e-beam shot, (2) high pattern fidelity by using CP stencil.
In this paper we address another advantage of CP exposure, namely the shape correction of CP stencil for cancelling the pattern deformation on the substrate. The deformation of CP printings is decomposed into some elements. They are CP stencil manufacturing error, proximity effect, beam blur of the e-beam writer and resist blur. The element caused by beam blur of e-beam writer can be predicted by measuring the total beam blur obtained from CD-dose curves. The pattern deformation was corrected by applying the shape correction software system of D2S. The corrected CP stencil of 22nm-node standard cell was manufactured and standard cell patterns were exposed. We confirmed that our shape correction method is the appropriate solution for correcting deformation issue of CP openings. The beam blur required for the 1X nm dimensions was predicted from the exposure results of standard cell patterns with applying shape correction and CD-dose curves. We simulated the optical system to realize the required beam blur. As a result, the next electron optics has the resolving capability of 1X nm dimension.
We investigated a high-resolution chemically amplified resist for introducing a multi-column cell electron-beam directwriting
system into the manufacturing of sub-14 nm technology node LSIs. The target of total blur, which leads to an
exposure latitude above 10%, is less than 13.6 nm for 14 nm logic node LSIs. We divided the total blur into three terms,
forward-scattering, electron-beam and resist. At a 40 nm-thick resist, the forward-scattering blur was calculated as 1.0
nm in lithography simulation, and beam blur was estimated to be 7.1 nm from the patterning results of hydrogen
silsesquioxane. We found that there is a proportional relation between resist blur and acid diffusion length by using a
new evaluation method that uses a water-soluble polymer. By applying a chemically amplified resist with a short acid
diffusion length, resist blur decreased to 14.5 nm. Even though total blur is still 16.2 nm, we have already succeeded in
resolving 20 nm line and space patterns at an exposure dose of 79.6 μC/cm2.
We successfully demonstrate complementary patterning with self-aligned double patterning (SADP) and currently used
e-beam direct writer (EBDW). The complementary patterning is achieved with not only positive type pattern for gate
layer but also negative type one for 1st metal (M1) layer at 11nm node. The e-beam exposure is performed by Advantest.
SADP process before e-beam exposure and etching after e-beam exposure are performed by Tokyo Electron. This paper
also reports EBDW applicability to complementary patterning for 8nm node and beyond in the light of overlay and
resolution, and improving plans including shot number reduction.
KEYWORDS: Logic, Multiplexers, Electron beam direct write lithography, High volume manufacturing, Semiconducting wafers, Semiconductors, Analog electronics, Chemical elements, Logic devices, Information fusion
We had previously established CP (character projection) based EBDW technology for 65nm and 45nm device production. And
recently we have confirmed the resolution of 14nm L&S patterns which meets 14nm and beyond node logic requirement with CP
exposure. From these production achievement and resolution potential, with multi-beam EBDW and CP function, MCC [1] could be
one of the most promising technologies for future high volume manufacturing if exposure throughput was drastically enhanced. We
have set target throughput as 100 WPH to meet HVM (high volume manufacturing) requirement. Our designed parameters to attain
100 WPH for 14nm result in 150 beams, 10cluster, 100 Giga shots/wafer, 250A/cm^2 and 75uC/cm^2.
In addition to multi-beam, drastic exposure shot reduction is indispensable to attain 100 WPH for 14nm node. We have aggressively
targeted 100 Giga shot count which is equivalent to covering 300mm wafer with 0.8um x 0.8um square fairly large tile. All device
circuit blocks should be structured with only CP defined parts and we should trace back to upstream design flow to RTL. We call this
methodology "CP element based design". In near future, Litho-Friendly restricted design would be commonly used [3] [4].
Our CP defined tile based regular layout would be highly compatible with these ultra-regular design approaches.
The primal design factors are Logic cell, Memory macro and random interconnect.
We have established concepts to accomplish high volume production with CP-based EBDW at 14nm technology node.
We evaluate the projection fidelity of the Cell Projection (CP) using the Multi column cell (MCC) proof of concept
(POC) tool [1-6]. The CP technology is originally developed as a method for reducing the shot counts of E-beam
lithography systems. However, the higher repeatability of the shape is expected because the fixed size CP mask openings
are used for each pattern. In the process of writing patterns by E-beam, the pattern deformation is inevitable due to the
beam blur, proximity effect, and beam shaping error. If the model of beam deformation is established, the correction for
the pattern deformation by modifications of CP mask opening shape can be carried out instead of additional shots. As a
result, the shot count will be reduced.
In this paper, we focused on Corner Rounding (CR) and Line End Shortening (LES) as two-dimensional properties of
pattern deformation. Two-dimensional deformation should be decomposed in two components. One is the deformation in
the process of CP mask manufacturing, and another is the deformation in the exposure process by e-beam writer tool. CP
mask has been manufactured, measured and analyzed by Toppan printing. And using the CP mask, the exposure process
error is measured by Advantest. By comparing the results, we evaluate the net amount of CP deformation caused in
exposure process. Finally we confirmed the two-dimensional deformation is predictable by blur length that is obtained
by one-dimensional CD-dose curve analysis.
We are evaluating the resolution capability of character projection (CP) exposure method using a Multi Colum Cell
Proof of Concept (MCC-POC) tool. Resolving of 14nm half pitch (HP) 1:1 line and space (LS) patterns are confirmed
with fine openings of a DNP fabricated CP mask for 10:1
de-magnification ratio. CP exposure has been proven to exhibit
high resolution capabilities even under the most challenging optimization conditions that are required for throughput
enhancement. As a result of evaluating the resolution capability of CP technology, it became apparent that the CP
technology has strong potentials to meet future challenges in two areas. One is where an increased number of CP with
variable illumination technology gives a higher throughput which has been the main objective behind the development of
this technology, and the other is to achieve higher resolution capability that is one of the strengths of CP exposure
method. We also evaluated the resolution on Quartz mask blanks instead of Si wafers and obtained 18nm HP 1:1
resolution with CP exposure.
Authors are developing a 50kV e-beam direct writer MCC8 [1] with 8 column cells that enables a throughput of 5 wafers
per hour. By March 2010, the concept of MCC had been proven with manufacturing the proof-of-concept system (MCCPOC;
four column cells) in the Mask-D2I project of Association of Super-Advanced Electronics Technologies (ASET).
Following the Mask-D2I project, the development has being focused on improving the position accuracy with MCCPOC
system as a direct write tool. The effort is expected to bring a smooth transition to MCC8. In this paper, newly
equipped correction technologies for improving the position accuracy is introduced; and the exposure results of field
stitching, inter column-cell(CC) stitching, and mix-and-match overlay on Si wafer are presented. Almost the same
accuracy results among all CCs are obtained. Mix-and-match overlay result is 5 nm in 3-sigma. Although inter-CC
stitching is not required in device manufacturing, but it will be shown as a part of pure evaluation of the tool
performance with the result of 5 nm in 3-sigma.
As the feature sizes of LSI become smaller, the increase in mask manufacturing time (TAT) and cost is becoming critical
and posing challenges to the mask industry and device manufacturers. In May 2006, ASET Mask D2I launched a 4-year
program for the reduction in mask manufacturing TAT and cost, and the program was completed in March 2010. The
focus of the program was on the design and implementation of a synergetic strategy involving concurrent optimization of
MDP, mask writing, and mask inspection. The strategy was based upon four key elements: a) common data format, b)
pattern prioritization based on design intent, c) an improved approach in the use of repeating patterns, and d) parallel
processing. In the program, various software and hardware tools were developed to realize the concurrent optimization.
After evaluating the effectiveness of each item, we estimated the reduction in mask manufacturing TAT and cost by the
application of results obtained from the Mask D2I programs. We found that mask manufacturing TAT and cost can be
reduced to 50% (or less) and to about 60% respectively.
KEYWORDS: Semiconducting wafers, Beam shaping, Vestigial sideband modulation, Logic devices, Electron beam direct write lithography, Photomasks, Analog electronics, Scanning electron microscopy, Optical transfer functions, Logic
The authors proposed a throughput enhancement of an e-beam direct writer by the combination of three key
technologies; multi column cell, character projection, and high current density column technologies. They have finished
proof-of-concept evaluations of multi column cell and character projection in the MASK-D2I project of ASET, including
mix-and-match overlay results of better than 5nm. They found adequate conditions for the application of these three
technologies to achieve the throughput above 5 wafers per hour in an e-beam direct writer.
In the Mask D2I project at ASET, the authors evaluated an e-beam multi column cell exposure system with character
projection to expose photomask patterns of 65nm and 45nm node logic devices with OPC corrections. They prepared
more than 2,000 characters in a deflection area of a character projection mask extracted from the 65nm node logic device
pattern. The character projection in the multi column cell system could expose patterns equivalent to those by the
conventional variable shaped beams. In a typical pattern layout of photomasks of 45nm node logic devices, the four
column cell system required the exposure time of about 1/3 of the time required by a single column system. The
character projection could reduce the exposure time corresponding to the reduction of shot counts. The pattern priorities
also reduced the exposure time as the result of shot count reduction and minimizing wait time for deflection settling.
In the Mask D2I project at ASET, the authors evaluated an e-beam multi column cell exposure system with character
projection to expose photomask patterns of hp65nm and hp45nm devices. They prepared more than 2,000 characters in a
deflection area of a character projection mask extracted from the hp65nm pattern. The character projection in the multi
column cell system could expose patterns equivalent to those by the conventional variable shaped beams. In a typical
pattern layout of photomasks for hp45nm devices, the four column cell system required an exposure time of about 1/3 of
the time required by a single column system. The character projection can reduce the exposure time corresponding to the
reduction of shot counts.
In the Mask D2I project at ASET, the authors assembled an electron beam exposure system to prove the concept ofmulti
column cell with character projection technology. They performed beam calibrations in individual column cells to
evaluate the resolution capabilities and stitching accuracies of the deflection fields of the system. Isolated 35nm line
pattern and 60nm 1:1 line-and-space pattern were exposed in each column cell. Present stitching errors among the
deflection fields were less than 15nm. We also evaluated stitching errors of patterns exposed by the different column
cells. The stitching errors among the column cells were estimated to be less than 20nm. We are now investigating the
origins of these errors to improve the exposure accuracies of the multi column cell system.
KEYWORDS: Analog electronics, Photomasks, Data corrections, Electron beams, Electromagnetism, Power supplies, Lenses, Digital electronics, Vestigial sideband modulation, Beam shaping
In the Mask D2I project at ASET, we are developing a novel electron beam exposure system using the concepts of MCC
(multi column cell), CP (character projection), and VSB (variable shaped beam) to improve the throughput of electron
beam exposure systems. In this paper we present the outline of a proof-of-concept system of MCC, results of the
evaluation of fundamental functions of the system, and early writing results including multi column stitching. In the
evaluation of fundamental functions of the system, we found that there is no interference on beam positions among the
CCs, and that the beam position stability is quite good. In our early writing experiments, we had presented the first
writing result of MCC and the first stitching result of a multi column system ever reported.
KEYWORDS: Beam shaping, Electron beams, Data corrections, Vestigial sideband modulation, Calibration, Lenses, Electromagnetism, Analog electronics, Digital electronics, Inspection
In the Mask D2I project at ASET, the authors designed a novel electron beam exposure system using the concepts of
MCC (multi column cell), CP (character projection), and VSB (variable shaped beam) to improve the throughput of
electron beam exposure systems. They presented outlines of a proof-of-concept system of MCC, and have shown the
performances of VSB and CP in the system. They evaluated the impacts on beam position in one column cell caused by
deflections in another column cell. The impacts were found to be less than 0.1nm in presence of major deflections in the
neighboring column cell. Hence it was concluded that there was no noticeable impact on deflections cause by the
neighboring column cells in the MCC system.
Association of Super-Advanced Electronics Technologies (ASET) Mask Design, Drawing,
and Inspection Technology Research Department (Mask D2I) started a 4-year development
program for the total optimization of mask design, drawing, and inspection technologies
to reduce photomask manufacturing costs in 2006. At the Mask Writing Equipment
Technology Research Laboratory, we are developing an e-beam exposure system
introducing concepts of MCC (multi column cell), CP (character projection), and
VSB (variable shaped beam), which has several times higher throughput than currently
commercially available e-beam writing systems.
This paper proposes a Mobile Multimedia Library (MML), a new application of information retrieval using camera-equipped mobile phones. MML allows users to get information of an unknown object anywhere and anytime. A user simply takes a picture of the object by a mobile phone and sends it directly to an MML server on which the picture is analyzed to identify the object. The MML server returns the identification result to the mobile phone and the user can browse information of the object on the display of the mobile phone. This application employs the k-Nearest Neighbor approach using eight MPEG-7 visual features to identify objects. A prototype system for animal identification has been developed to demonstrate effectiveness of the MML framework. It takes about ten seconds on average for the identification in which 63% and 79% queries were correctly identified within first four and first ten candidates, respectively, out of 229 categories.
As the technology roadmap continuously goes along, pattern density increases beyond more than 250 G shots per a mask until 2010. However the total usable beam current is limited by Coulomb interaction to maximum several hundred nanoampere and by the settling time of positioning amplifier the shot rate is restricted to around 10 MHz. To overcome those restrictions we propose MCC (Multi-Column cell with Lotus Root lens) system to use for mask making. In this system plural numbers (4 or 16) of square variable shaped beams and some kinds of Cell Projection beams including triangles and fundamental DRAM or SRAM patterns are independently controlled to expose simultaneously different parts of a glass substrate. Coulomb interaction between beams of different CCs no more exists and parallel writing is carried out. With this system a mask can be exposed from four to sixteen times faster than present single column system. We evaluated the beam performance of the electron optics Proof of Concept (PoC) system of Multi-Column Cell (MCC) method. As for the two beams at the near center of 4 x 4 layout with 25 mm pitch they show the good uniformity and low interference.
KEYWORDS: Resolution enhancement technologies, Electron beams, Lithography, Silicon, Electron beam lithography, Tantalum, Scanning electron microscopy, Photomicroscopy, Very large scale integration
In the electron beam (e-beam) block exposure lithography, the coulomb interaction effect is a critical problem. In this paper, impact of the coulomb interaction effect on delineating 0.1 micrometer/0.2 micrometer L/S patterns is investigated. We have delineated 0.1 micrometer/0.2 micrometer L/S patterns and have found that line widths and delineation conditions are greatly dependent on the shot current. Two methods for reducing the shot current were examined. By narrowing the line width of L/S patterns from 0.15 micrometer to 0.05 micrometer, the contrast of the e-beam profile increased from 16% to 87% and the dose latitude increased from 0 (mu) C/cm2 to 18 (mu) C/cm2. On the other hand, by reducing the shot size from 4.5 micrometer multiplied by 4.5 micrometer to 1.5 micrometer multiplied by 4.5 micrometer, the contrast of the e-beam profile increased from 16% to 61% and the dose latitude increased from 0 (mu) C/cm2 to 4 (mu) C/cm2. Even though both methods reduce the shot current 1/3, further resolution enhancement is obtained for the former method. We have found that reducing shot current by narrowing the line width is preferable in order to enhance the resolution of L/S patterns.
This paper describes a novel intelligent low bit rate coding technique for motion pictures, named Video Sequence Quantizer (VSQ). VSQ is one of the semantic coding. The concept is very simple. The encoder extracts motion information about target objects and transmit it as a few control parameters. The decoder has several video sequences in its database and outputs them selectively according to the transmitted parameters. It can reproduce natural movements with a simple operation compared with another semantic coding scheme called computer graphics model-based coding. We make clear the concept of VSQ and also apply it to a very low bit rate TV phone system. Computer simulation of TV phone has been done using twelve video sequences. It can naturally reproduce the speaker's movements by 80 bit/sec. VSQ is a very simple but basic concept for video coding. It will be also useful for mobile and multimedia communications.
The optimal analysis/synthesis filters giving the maximum coding gain are derived in subband schemes. The optimal analysis filters consist of the emphasis of the picture signal and ideal band-splitting. The characteristics of the emphasis is determined by the spectrum of the picture signal. A large improvement of coding gain is achieved by the subband scheme with the optimal subband filters obtained here. Approximated emphasis characteristic determined from a spectrum model of picture signals can be used and the ideal band-splitting filters can be replaced by conventional subband filters since the degradation of coding gain due to these approximations is small. Computer simulation of super HD image coding by the proposed scheme is performed. SN ratio of the reconstructed image is increased and edges are reconstructed very well compared to the conventional subband scheme. The proposed scheme is very suited to super HD image coding since the improvement of SN ratio is large for images with high correlation between the neighboring pixels.
The subband scheme is one of the most promissing schemes for super HDTV coding. In this paper, we propose two types of multidimensional multichannel subband scheme. Using the concept of the complementary subsampling, the properties of the analysis and synthesis filters axe analyzed. Coding gain is calculated for the proposed scheme by using a picture model. The proposed scheme shows coding gain higher than the conventional scheme.
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