Composition and detection of alignment marks for electron-beam lithography

Wolf, E. D.; Coane, P.; Ozdemir, F. S.

doi:10.1116/1.568514

Cited by 22 publications

(2 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[1][2][3] With reduced beam current and therefore reduced signal-to-noise ratio ͑SNR͒, the threshold determination becomes more and more difficult and will, in certain cases, be impractical. In the operation of an automatic alignment, it is important to determine the correlation position between marks in the chips and marks in the template because the precision of the correlation position plays a key role in alignment precision.…”

Section: Introductionmentioning

confidence: 99%

Algorithm method of correlation position for automatic alignment in microcircuit fabrication

Wang¹

1995

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

View full text Add to dashboard Cite

A new algorithm method used to determine the correlation position between two marks for automatic alignment in microcircuit fabrication has been developed. This algorithm maintains the correlation technique advantage such as its high immunity to noise and poor contrast in the mark signal. The alignment overlay precision achieved is better than one pixel. By using this algorithm method, the 486-33PC computer takes about 4 s to determine the correlation position without any special hardware. This article describes the method along with giving experimental results.

show abstract

Section: Introductionmentioning

confidence: 99%

Algorithm method of correlation position for automatic alignment in microcircuit fabrication

Wang¹

1995

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

View full text Add to dashboard Cite

show abstract

“…Many authors (1)(2)(3)(4)(5)(6)(7)(8)(9) have contributed to character-~zmg alignment signals. Wolf et al (1) reported measurements of alignment signals for silicon pedestals, silicon dioxide channels, and gold marks. Friedrich et al (2) considered the alignment signals from Vshaped silicon marks.…”

mentioning

confidence: 99%

Alignment Signals from Symmetrical Silicon Marks for Electron Beam Lithography

Lin

Neureuther

Oldham

1983

J. Electrochem. Soc.

View full text Add to dashboard Cite

This paper discusses the experimental observations of alignment signals from symmetrical U-, V-, and W-shaped silicon marks. Solid-state detectors are used to measure alignment signals by collecting electrons backscattered in different takeoff angle regions. The results indicate several methods for improving the signal quality. The effects on the alignment signals due to the resist coatings are measured particularly for PMMA coated on V-marks at different positions on the wafer. The experimentally observed resist profile is characterized by the degree of planarization, which in turn is used to evaluate the reduction of the signal level due to the coated resist thickness. The detection uncertainty error due to the asymmetry of the resist profile at a peripheral position of the wafer is evaluated. The accuracy in locating the alignment marks is also calculated as a function of the expanded signal-to-noise ratio, the number of scans of the electron beam, and the depth of the mark. Simple design rules are given for characterizing the effects of resist thickness, the incident beam voltage, and the mark depth in terms of the Bethe range.The direct exposure of wafers in electron beam lithography (EBL) requires the capability of accurately overlaying the pattern to be exposed to the processed pattern already on the wafer. For this purpose, alignment marks are typically fabricated at the four corners of each chip. The alignment process is carried out by scanning the electron beam across the alignment marks, and collecting backscattered electrons which penetrate the resist layer. To avoid additional process steps it is desirable to align without removal of the resist coated over the alignment marks. . Many authors (1-9) have contributed to character~zmg alignment signals. Wolf et al. (1) reported measurements of alignment signals for silicon pedestals, silicon dioxide channels, and gold marks. Friedrich et al. (2) considered the alignment signals from Vshaped silicon marks. Iida and Everhart (3) examined anisotropically etched silicon holes as alignment marks. Davis et al. (4) discussed the optimization of the alignment mark detection process from U-shaped silicon marks. Stickel (5) developed a qualitative model to describe the effects of the separation between the two sidewalls of a U-shaped mark on the signals observed experimentally using solid-state detectors in four quadrants. A more quantitative technique based on Monte Carlo (MC) simulati0ns has been used by Aizaki (6) to explore the total backscattered signals from step, V-, and W-shaped grooves in silicon. In a similar study, Stephani (7) investigated the backscattered signals in different takeoff and azimuthal angles from rectangular steps, pedestals, and grooves.The authors have also employed the MC method to characterize the alignment signals (8-9) formed by electrons backscattered from tapered silicon steps both with and without resist coatings. In our investigations, we have found that the preferred detector configurations collect the low takeoff angle electr...

show abstract

Radiation Exposure

Moreau¹

1988

Semiconductor Lithography

View full text Add to dashboard Cite

Composition and detection of alignment marks for electron-beam lithography

Cited by 22 publications

References 0 publications

Algorithm method of correlation position for automatic alignment in microcircuit fabrication

Algorithm method of correlation position for automatic alignment in microcircuit fabrication

Alignment Signals from Symmetrical Silicon Marks for Electron Beam Lithography

Radiation Exposure

Contact Info

Product

Resources

About