摘要:

Slow throughput is the major problem of scanning beam lithography. We have investigated a multiple beam approach in which an array of beams is focused and scanned by a common system but the beams are blanked independently. The individual blanking is accomplished using an assembly fabricated with silicon micromachining technology and shadow mask evaporation of blanking electrodes 50 μm wide, 400 μm deep. Analysis and experimental evaluation both indicate that blanking can be achieved with this configuration. Choosing an optimum design involves trade offs between ease of illumination, ease of fabrication, positional control, and space charge blurring. However, extension to 16 or more beams looks quite possible.

ISSN:1071-1023    

DOI:10.1116/1.582722

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

The application of IBM’s 3rd generation direct write electron beam lithography tool EL‐3 has been extended into the submicron region. This was accomplished with tool modifications in conjunction with suitable process adjustments. EL‐3 is presently being used in both development and manufacturing for the exposure of wafers and masks. It was designed as a high current, high throughput tool to cover lithography requirements down to 1 μm minimum dimensions. To move into the 0.5 μm realm, no basic architecture changes were made, but the beam current, deflection speeds, and maximum spot and field sizes were reduced to make the trade‐offs against throughput that were necessary and acceptable for the system’s application to technology development. A single layer resist process was devised to demonstrate fully the performance capability of the tool. The process uses top surface imaging which allows one to analyze tool performance without excessive distortions. Spot‐to‐spot butting and illumination consistency were monitored using this process. Linewidth tolerance and overlay results obtained with the new tool/process configuration will be reported. Top surface imaging, whether in a single or multilayer resist process, represents the most viable approach for submicron electron‐beam lithography.

ISSN:1071-1023    

DOI:10.1116/1.582662

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

A new definition called ‘‘edge contrast’’ is proposed for realistic resolution comparisons between tools of different beam technology. This new quantity does not pre‐empt the traditional intensity contrast definition, but extends it. Taken into account are both the intensity levels in areas to be exposed and not to be exposed, as well as the transition variations (edge slope) between them. As a result, it will be shown that, compared to light‐optical tools, electron beam systems have a resolving capability already superior in the range of feature dimensions well above 1 μm. A comparison on the basis of the intensity contrast definition would place the point of equivalency in the vicinity of 0.5 μm. The new definition is not only adequate to characterize the lithography tool, but also suitable to encompass the entire process chain provided the functional dependencies between the process parameters are known.

ISSN:1071-1023    

DOI:10.1116/1.582663

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

Field emitters offer a particularly high potential in e‐beam lithography when writing in the nanometer range. Using a modified VG Microscopes Ltd., model HB 501 STEM, a current of 0.1 nA can be focused into a diameter of 2.5 nm at 100 kV with a final beam aperture of 1.6 mrad. In order to fulfill the demands of microlithography, an objective lens of 15 mm nominal focal length is used. Stage travel in the system is 5 mm in theXandYdirections and the maximum scan field is 250×250 μm2. The beam is deflected electromagnetically under computer control and vector scanning is used during lithography. The 14 bit digital pattern generator has been electrically isolated by optocouplers from the host computer and is connected via analog differential buffers to the deflection amplifiers. The cold tungsten field emitter exhibits a linear decrease in current of about 20% within 20 min of continuous writing. The decrease in current is corrected during lithography by a feedback to the clock frequency of the digital pattern generator to maintain a constant exposure dose. The high current available enables the use of organic resists as well as low sensitivity inorganic resists such as NaCl or WO3. So far 10 nm resolution has been achieved byinsituvaporization of NaCl.

ISSN:1071-1023    

DOI:10.1116/1.582664

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

Direct current electrical tests have been used to measure the performance of electron beam resists and an exposure system. Resist characterization is done by using electrical tests to measure the linewidth defined as a function of an incremental dose. The quality of different resists can be compared by means of δ, the slope of the normalized linewidth versus the logarithm of the incident dose curve. Data have been measured for three negative resists (PCMS 30, PCMS 200, and OEBR 100) and PMMA for two development conditions. Resistors fabricated from 60 nm chromium films, 300 nm polysilicon films, or 60 nm titanium films gave results within ±40 nm of one another for 500 nm lines. Without proximity effect correction, linewidth difference from design value is more than ±300 nm and the 0.5Pμm lines were undefined for PMMA and the given development conditions, and 0.5Pand 1.0Pμm lines were undefined for PCMS 30 and the given exposure conditions. With proximity effect correction, all line sizes are within 100 nm of design value with the exception of 0.5Pμm in PCMS 30. The beam diameter varies from an undeflected value of 350 nm to a maximum of 650 by 480 nm, without dynamic corrections, as calculated from measurements of 500 nm lines placed throughout the 5 mm field of view. Two‐level alignment measured electrically in the center and four corners of the 5 mm field is within 100 nm, with standard deviations typically less than 60 nm at each location for each axis. Butting of exposure subfields, measured electrically, is within 80 nm; the one sigma standard deviation of this measurement is 42 and 82 nm for thexandyaxes, respectively, but is less than 15 nm at a higher exposure frequency.

ISSN:1071-1023    

DOI:10.1116/1.582665

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

Electron image projection is an attractive technique for making submicron integrated circuits (IC) but long and short range proximity effects cause some pattern distortion. Long range proximity effects have now been measured and the significance of long and short range effects to IC fabrication assessed. Long range proximity exposure effects due to re‐entrant electrons are sufficiently uniform for local corrections to be unnecessary. With automatic proximity correction IC patterns could be scaled down to below 0.5 μm (1 μm pitch) even with single level resist and 20 keV electrons.

ISSN:1071-1023    

DOI:10.1116/1.582666

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

Electron beam proximity printing is a lithography method for high throughput exposure of repetitive patterns with submicron structures. An electron beam shadow projects the pattern contained in a transmission mask onto the wafer. Pattern registration in this projection printer is achieved by using the electron beam current absorbed in the wafer. Two registration steps are employed: one for wafer (or global) align, the other for chip (or local) align. The achieved registration accuracy is better than 0.1 μm using 10 keV electrons and 1.1 μm thick PMMA on the wafer registration marks.

ISSN:1071-1023    

DOI:10.1116/1.582667

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

The flexibility of broad‐beam ion processing when used in conjunction with a chemistry assist technique is demonstrated. In this technique called chemically assisted ion beam etching (CAIBE), a chemically reactive gas is introduced into the sample chamber independent of the ion source which can be operated on inert or reactive gases. This allows for a wide range of independent control of the chemical and ionic fluxes not available in other dry etching techniques. Using a two component gas system of argon and xenon difluoride vapor under various operating conditions, the etched wall profiles of Si were found to be controllable. In the reactive ion beam etching mode of operation, overcut profiles with enhanced etch rates over ion milling rates were produced from Ar+and XeF+xbeams resulting from predominantly physical etching mechanisms. With the introduction of low vapor pressures of XeF2into the sample chamber in conjunction with Ar+ion bombardment, profiles resulted from line‐of‐sight ion assisted etching. Vertical walls were obtained with a collimated ion beam while profiles with directional undercutting resulted under highly divergent beam conditions. By increasing in XeF2vapor pressure, undercut profiles from purely chemical etching were formed. Thus, by varying the partial pressure or the ion source operating conditions during an etch process, profile tailoring was accomplished.

ISSN:1071-1023    

DOI:10.1116/1.582668

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

A new ultrafine line pattern inversion and transfer technique based on local low temperature plasma oxidation and reactive ion etching of suitable metal films, such as aluminum, is presented. The patterned surface oxidized metal film may serve as a surface passivated interconnect or gate structure for integrated semiconductor devices, or be used as an etch mark for underlying layers. As an application a process for patterning self‐aligned two layer gate lines composed of molybdenum silicide and polycrystalline silicon is given. Linewidths as small as 1500 Å have been achieved.

ISSN:1071-1023    

DOI:10.1116/1.582669

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

Refractory metal silicides andn+polysilicon/silicides are of particular interest for VLSI gate and interconnection technology. Reactive ion etching experiments have been conducted on sputter‐deposited films of MoSi2, CVDn+polysilicon, and thermal SiO2using admixtures of SF6with O2. The influence of partial pressure and total pressure on profile control and etch selectivity has been determined. Highly anisotropic etching ofn+polysilicon and MoSi2was obtained using a gas mixture of SF6plus 50% oxygen. Examples of 0.2μ anisotropically etched structures of silicides andn+polysilicon/silicide stacked films have been realized using electron beam lithography and one step dry etching. Mechanisms of profile control involved in the SF6/O2system are discussed. In addition, exploratory reactive ion etching studies using SiF4/Cl2gas mixtures for these materials and TaSi2have been carried out.

ISSN:1071-1023    

DOI:10.1116/1.582670

出版商:American Vacuum Society    

年代:1983

数据来源: AIP