摘要:

This article describes the correlation of UVIIHS resist chemistry to dissolution rate measurements as a function of resist processing conditions. The acid generation efficiency, α, for the UVIIHS photoacid generator is high, 0.027 cm2/mJ. The dissolution rate versus exposure curves show the excellent developer selectivity of UVIIHS, withnvalues>8 for all processes. Thermaxvalues for this resist are above 20 000 Å/s, which is higher than any positive resist previously reported. The extent conversion for deprotection is directly related to the dissolution rate changes; ∼30% deprotection correlates to theE0dose for all process conditions evaluated. At 30%–40% acid produced, all of the deprotection chemistry is essentially completed. The chemical contrast, as measured by extent conversion versus exposure dose, is strongly affected by the postexposure bake (PEB) temperature, with 140 °C PEB showing higher chemical and lithographic contrast than the 130 °C PEB. Mack’s dissolution model has been shown to work for these data sets.

ISSN:0734-211X    

DOI:10.1116/1.588588

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

New nonpolymer materials, calixarene derivatives were tested as high‐resolution negative resists for use in electron beam lithography. Arrays of 12‐nm‐diam dots with a 25 nm pitch were fabricated easily. The sensitivity of calixarene in terms of area dose ranged from 700 to 7000 μC/cm2, and the required dose for dot fabrication was about 105electrons/dot. The standard area dose for calixarene is almost 20 times higher than that for polymethyl methacrylate (PMMA), but the electron spot dose for dot fabrication by calixarene is almost the same as that for PMMA and other highly sensitive resists such as SAL (chemically amplified negative resist for electron beam made by Shipley). The electron spot dose for such extremely small dots does not seem to depend on standard area dose, but any resist tends to require the same dose under exposure in a 50 keV electron beam writing system. We propose a qualitative exposure model that suggests a tradeoff of dose and dot size. The calixarene seems to be promising material for nanofabrication.

ISSN:0734-211X    

DOI:10.1116/1.588589

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

The effective backscatter coefficient η is a quantity that must be known with precision so that the proximity effect can be adequately compensated to minimize feature size variations in electron beam lithography. A unique technique to measure η that does not require the precise form of the backscatter dose distribution was employed. This method simply compares the resist response near the center of printed features that are much smaller and much larger than the characteristic range of the long range scatter. This technique was already employed to estimate the backscatter coefficient on Si at 100 keV beam energies. We have extended this measurement to determine η at lower beam energies. Results show that η on Si is 0.38, 0.50, 0.55, and 0.46 for 100, 50, 40, and 20 keV beam energies, respectively. Monte Carlo simulations indicate a trend of decreasing η with increasing beam energy, consistent with the experimental results except at 20 keV.

ISSN:0734-211X    

DOI:10.1116/1.588590

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

High voltage electron beam lithography experiments on thin films of tungsten trioxide are reported. For linear doses around 10 mC/cm at 200 kV, a negative resist behavior is observed after development in a NaOH solution. Features with dimensions as low as 15 nm with aspect ratios up to 10, exhibiting weak size fluctuations and vertical sidewalls are routinely achieved. Proximity effects are found to be negligible allowing the fabrication of structures with less than 10 nm separation. The exposure mechanism is investigated by transmission electron microscopy and diffraction. A crystallization process induced by the electron bombardment is clearly evidenced. A model based on the amorphous to crystalline phase transition induced by electron irradiation is proposed to account for the experimental observations.

ISSN:0734-211X    

DOI:10.1116/1.588591

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Previous experimental and theoretical evidence indicates that x‐ray lithography can be used to pattern ≤180 nm features. In order to be used in manufacturing, x‐ray lithography of complex integrated circuit patterns (i.e., dense two‐dimensional patterns) needs to be demonstrated with a practical proximity gap. However, no large body of experimental evidence exists for the extendibility of x‐ray lithography for complex patterns with ground rules of ≤130 nm at gaps of 10–20 μm. Simulations of image formation and resist dissolution are shown to have good agreement with experimental results. These simulations are then used to predict exposure latitude and gap latitude for printing one‐dimensional 75–125 nm patterns at 10–15 μm gaps. Simulations indicate that at least ±10% exposure dose latitude will exist for simple patterns at these gaps, but significant nested‐to‐isolated linewidth bias will exist. Gaps must be controlled to ±1 μm for ±10% dose latitude. More complex two‐dimensional patterns have been shown to exhibit line end shortening [J. Maldonado, R. Dellaguardia, S. Hector, M. McCord, and L. Liebmann, J. Vac. Sci. Technol. B13, 3094 (1995)] that simulations qualitatively indicate a rise in part due to image formation. Simple serifs on line ends may be needed to reduce line end shortening.

ISSN:0734-211X    

DOI:10.1116/1.588592

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

This article discusses the resolution of synchrotron radiation lithography in the sub‐100 nm region, taking into consideration the mass production of large‐scale integrated circuits, under attainable conditions for the x‐ray mask, proximity gap, and resist processes. Resolution and exposure latitude for line‐and‐space patterns are markedly improved by using a mask with a contrast of only 2.5. Resolutions of 90, 80, 70, and 60 nm can be achieved with proximity gaps of 30, 20, 15, and 10 μm if a high‐contrast resist and a low‐surface tension developer are used. The latitude will be 10% for pattern sizes as small as 70 nm when the proximity gap is narrower than 15 μm. The effects of mask duty [which is defined to be the ratio of the absorber (line) width to the pattern pitch, i.e., duty cycle] on the optimum exposure dose and mask linearity are also evaluated.

ISSN:0734-211X    

DOI:10.1116/1.588593

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

The feasibility of x‐ray lithography in applying device process was studied through fabrication of a small circuit consisting of experimental stacked film and contact holes numbering about 1k with replicated sizes from 0.6 to 0.085 μm. To resolve fine contact holes, in‐house chemically amplified positive resist was used by employing a high contrast post‐exposure‐bake condition. By measuring the resistance and yields of prepared circuits, we have evaluated the reliability of the circuits. High yield of larger than 0.9 was obtained for contact holes larger than 0.15 μm, and prepared circuits were found to be feasible down to 0.085 μm.

ISSN:0734-211X    

DOI:10.1116/1.589040

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Canon has been developing a synchrotron radiation stepper system for x‐ray lithography feasibility studies. We have developed a novel accurate alignment system using the dual grating lens (DGLs) method. In this article, we explain the principle of the DGL, and the results of the alignment accuracy and process applicability tests. We have evaluated alignment performance for translation (X,Y) and rotation (θ) at the center of every exposure area. We obtained the alignment accuracy 3σ of 19 nm (X), 15 nm (Y) and 0.8 μrad (θ), using etched SiN patterns on Si substrates, and the overlay accuracy in an actual dynamic random access memory fabrication process 3σ of 34 nm (X), 31 nm (Y), and 2.1 μrad (θ). After eliminating the alignment offset in each shot, the values (3σ) are 18 nm, 21 nm, 1.4 μrad, respectively. These results show that the alignment method is promising for 0.15 μm level device fabrication.

ISSN:0734-211X    

DOI:10.1116/1.589041

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

To produce x‐ray masks useable for 0.25 μm lithography and beyond, all sources of mask distortion must be minimized. In order to facilitate the fabrication of high‐quality masks, the phenomenon of changes in resist stress during e‐beam exposure has been studied. Finite element modeling was employed to determine the effects of various geometric and material properties on final image quality. Additionally, writing patterns and multipass exposure were also studied. The results indicate that the stress relief phenomenon can be controlled in a well‐designed system.

ISSN:0734-211X    

DOI:10.1116/1.589042

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

A nanofabrication technology providing device isolation at an active pitch of 300 nm has been developed using x‐ray lithography for pattern definition. The isolation scheme uses oxide filled trenches etched into the silicon substrate, which are 300–350 nm deep and have a 150 nm minimum width. Chemical mechanical polishing is utilized to achieve global planarization. The superior diode leakage and gate oxide (tox=55 Å) performance, excellent metal–oxide–semiconductor field effect transistor characteristics, and robust latch‐up behavior demonstrated by this trench isolation technology, present it as a key enabler for continued scaling of semiconductor technologies. The experimental data presented predicts that with careful attention to process integration, trench isolation can be scaled well into the sub‐0.25 μm size scale.

ISSN:0734-211X    

DOI:10.1116/1.589043

出版商:American Vacuum Society    

年代:1996

数据来源: AIP