摘要:

The ultimate lithographic performance of e‐beam direct writing can only be achieved if the proximity effect is reduced by a top surface imaging resist technology. The capability of some commercial and experimental chemically amplified resists for an e‐beam‐sensitive top surface imaging process were evaluated. Analogous to the resist contrast, a silicon contrast was defined, which characterizes the silylation property of the resists very well and enables a comparison of the evaluated resists. The influence of bake and silylation conditions on the silicon contrast was investigated. The patterning results prove that the proximity effect was reduced dramatically. One of the evaluated resists was applied to structuring the metal layers of a 0.8‐μm‐CMOS technology.  

ISSN:0734-211X    

DOI:10.1116/1.587576

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

We present an updated global model for x‐ray lithography based on realistic models for image formation, demonstrating how the extendibility of x‐ray lithography is well in the nanometer range. We apply these models to define the most convenient spectral range for x‐ray lithography manufacturing and the parameters of mirrors and filters to be used in an optimized beam line.

ISSN:0734-211X    

DOI:10.1116/1.587577

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

Data on image shortening effects with patterns replicated with x‐ray and optical lithography are presented. The x‐ray exposures were performed at the IBM Advanced Lithography Facility using the Helios superconducting storage ring and a SUSS stepper. The optical exposures were performed using SVGL Micrascan 1 and 2 tools and biased optical masks. The results indicate that the image shortening effects using x‐ray lithography (XRL) are considerably less pronounced than the effects observed with the optical tools. In addition, modeling of the image shortening effects for XRL using thexmasthree‐dimensional program for resist patterns is presented and compared with experimental results.

ISSN:0734-211X    

DOI:10.1116/1.587578

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

Sub‐quarter‐micron gate‐level device development and process integration of a complimentary metal oxide semiconductor (CMOS) program are being supported at IBM Microelectronics’ Advanced Semiconductor Technology Center with both synchrotron orbital radiation lithography (proximity x‐ray) and phase‐edge deep ultraviolet phase‐shifted‐mask lithography. Data highlighting the feasibility of these two advanced techniques for the lithography support of very aggressive CMOS technologies are presented. Issues of design complexity, design rule impact, and mask engineering are discussed, the exposure process is described, and current process latitude data are presented. Both lithography techniques show feasibility for 200 nm lithography, each with its unique set of challenges and trade‐offs.  

ISSN:0734-211X    

DOI:10.1116/1.587579

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

To evaluate the applicability of synchrotron radiation x‐ray lithography (SRXL) in ultra‐large‐scale integration manufacturing processes, we simulate a part of a dynamic random access memory process using SRXL. Four levels of x‐ray masks (field, gate, bit contact, and bit line), including fiducial patterns for coordinate/overlay measurement, alignment marks, and 0.4‐μm‐rule memory cells were fabricated using ani‐line stepper. The maximum overlay error between the different level masks was 60–100 nm. In SRXL processes alignment errors of the x‐ray stepper were 60–100 nm (3σ), and the overlay errors over a 20‐mm‐exposure field were 130–160 nm (‖mean‖+3σ) in most of alignment levels. Critical dimension control of 27–47 nm was obtained for gate length and contact hole diameter.

ISSN:0734-211X    

DOI:10.1116/1.587580

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

This article reports the manufacturing process of 250 nm resolution x‐ray masks featuring gold absorbers optimized for synchrotron radiation lithography in both thickness and absorber slope. X‐ray optics modeling predicts that nonvertical absorber flanks may provide better linewidth control by suppressing higher spatial frequencies. To test these conclusions, masks were patterned by electron beam lithography at accelerating voltages of 30 kV with the final goal of developing various slopes and feature sizes. Monte Carlo simulation is used to predict the best exposure conditions. An intelligent usage of the resist thickness and exposure conditions allow us to exploit forward scattering of electrons to provide the required resist profile in a well controlled way. By adjusting exposure dose and development time, the slope profile can be altered from 90° to about 82°. We demonstrate that lines and spaces of 250 nm with controlled and repeatable profile slope of 87° are achievable in 400‐nm‐thick gold with good exposure latitude. Under such optimized process conditions a dose variation of 10% leads to a 10% linewidth change for 250 nm features. Exposure latitude for all the writing conditions was also determined. Finally, we performed x‐ray exposure using a mask including both sloped and nonsloped absorbers using Suss XRS 200/2M aligner at the Centre for X‐Ray Lithography of the University of Wisconsin (CXrL). The results confirmed the theoretical model used in image calculations, providing experimental evidence that the exposure latitude is not degraded, but actually improves in case of sloped patterns.

ISSN:0734-211X    

DOI:10.1116/1.587409

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

A technology of proximity x‐ray lithography has been developed to replicate patterns of sub‐100‐nm feature size using synchrotron radiation. Process modeling has been done in advance in order to optimize the mask absorber thickness. It is shown that with tungsten absorber, a 0.3 μm thickness is the most desirable for 50 nm linewidth processing. Masks compatible with a Karl Suss stepper have been fabricated using 50 keV electron‐beam lithography and reactive ion etching techniques. As a result, well‐defined 50‐nm‐wide isolated W lines and small gratings of period down to 100 nm have been fabricated. Then they have been replicated under proximity condition using Super ACO synchrotron radiation. We present details of a replication procedure with gap settings down to 5 μm and show how sub‐100 nm structures can be 1:1 printed into both poly (methylmethacrylate) (PMMA) and (8.5%) MAA/PMMA resists. Finally, the results are analyzed in terms of a scaling rule to evaluate the resolution limit as a function of proximity gap using a synchrotron source.

ISSN:0734-211X    

DOI:10.1116/1.587410

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

Image formation in x‐ray lithography has been studied extensively. A previous theoretical study predicted that 0.1 μm features can be printed at large gaps (≳10 μm) with absorbers attenuating less than 10 dB. This study seeks to verify rigorous electromagnetic simulations of image formation by directly measuring the aerial image. Exposures of features with linewidths ranging from 0.15 to 0.075 μm were performed on the Helios synchrotron. Pedestal‐style x‐ray masks, consisting of SiNxmembranes and a Au absorber, were patterned with e‐beam lithography at 100 and 50 kV. By careful dose control and inspection of the resulting features, one can directly determine the aerial image (the image at the resist surface). This is verified using a string model of the resist development. Aerial image measurements correlate reasonably well with modeling results.

ISSN:0734-211X    

DOI:10.1116/1.587411

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

Functional 150‐nm gate‐length high electron mobility transistors (HEMTs) have been successfully fabricated using storage ring x‐ray lithography (XRL) for all process levels. This article describes the L2M XRL exposure system including x‐ray masks, the planar‐doped GaAlAs/GaAs HEMT fabrication process, and the characteristics of the resulting devices. The gate length, a key device performance parameter, was minimized down to 150 nm using an optimized chemically amplified SAL601 negative resist process at small proximity gap (≤20 μm). This optimization process indicates that process latitude and resolution are primarily limited by the post‐exposure bake (PEB) step which has been adjusted to 95 °C. The fabricated HEMTs have excellent dc characteristics with a peak extrinsic transconductance as high as 400 mS/mm.

ISSN:0734-211X    

DOI:10.1116/1.587412

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

The focus of this paper is to introduce and describe a new technique for the determination of x‐ray lithography mask distortions for pre‐ and post‐irradiated membranes using a combination of numerical, analytical, and experimental methods. At the heart of this technique is a new test structure and fixture that allow for the accurate determination of material properties so that changes due to radiation exposure can then be incorporated into a finite element model to predict distortions. In addition, due to the size of the membranes used for the test structure, larger accumulated doses can be delivered in shorter periods of time. Once the material property and stress changes have been incorporated into numerical models, calculations can then be performed to simulate the effect of radiation on various membrane pattern areas and geometries.  

ISSN:0734-211X    

DOI:10.1116/1.587413

出版商:American Vacuum Society    

年代:1994

数据来源: AIP