Super-smooth x-ray reflection grating fabrication

被引:44
作者
Franke, AE [1 ]
Schattenburg, ML
Gullikson, EM
Cottam, J
Kahn, SM
Rasmussen, A
机构
[1] MIT, Cambridge, MA 02139 USA
[2] Univ Calif Berkeley, Lawrence Berkeley Lab, Ctr Xray Opt, Div Mat Sci, Berkeley, CA 94720 USA
[3] Columbia Univ, Dept Phys, New York, NY 10027 USA
来源
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B | 1997年 / 15卷 / 06期
关键词
D O I
10.1116/1.589759
中图分类号
TM [电工技术]; TN [电子技术、通信技术];
学科分类号
0808 ; 0809 ;
摘要
Blazed, grazing incidence x-ray reflection gratings are an important component of modern high resolution spectrometers and related x-ray optics. These have traditionally been fabricated by diamond scribing in a ruling engine, or more recently by interferometric lithography followed by ion etching. These traditional methods result in gratings which suffer from a number of deficiencies, including high surface roughness and poor control of the groove profile. These deficiencies lead to poor diffraction efficiency and high levels of scattered light. We have developed a novel fabrication method for fabricating blazed x-ray reflection gratings which utilizes silicon wafers that are cut 0.7 degrees off of the (111) plane. In solutions such as potassium hydroxide (KOH), silicon is etched in [111] directions orders of magnitude slower than in other directions, resulting in extremely smooth {111} facets. The gratings are patterned using interferometric lithography with 351.1 nm wavelength and transferred into the substrate using tri-level resist processing, reactive-ion etching (RIE), and silicon nitride masking during the KOH etch. The narrow (<0.1 mu m) ridge of silicon which supports the nitride mask is removed using a chromium lift-off step followed by a CF4 RIE trench etch. The result is a grating with extremely smooth blaze facets which is suitable for x-ray reflection after evaporative coating with thin Cr/Au. Atomic force microscope images confirm that fabricated gratings have less than a 0.4 nm rms roughness-much smoother than conventional gratings which have over similar to 1 nm roughness. Theory predicts that reduced blaze facet roughness increases diffraction efficiency, Experiments and simulations performed at the Lawrence Berkeley Laboratory and Columbia University confirm that efficiency is increased; in fact, measured peak efficiencies reach similar to 80% of calculated theoretical limits. Peak grating efficiencies were achieved that are similar to 35% greater than that of the best available ruled masters of comparable design. (C) 1997 American Vacuum Society.
引用
收藏
页码:2940 / 2945
页数:6
相关论文
共 17 条
  • [1] BIXLER JV, 1991, P SOC PHOTO-OPT INS, V1549, P420, DOI 10.1117/12.48358
  • [2] CIARLO DR, 1986, P SOC PHOTO-OPT INS, V688, P163
  • [3] Analysis of distortion in interferometric lithography
    Ferrera, J
    Schattenburg, ML
    Smith, HI
    [J]. JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B, 1996, 14 (06): : 4009 - 4013
  • [4] Franke A. E., 1997, THESIS MIT
  • [5] OPTICAL DEMULTIPLEXER USING A SILICON ECHELETTE GRATING
    FUJII, Y
    AOYAMA, KI
    MINOWA, JI
    [J]. IEEE JOURNAL OF QUANTUM ELECTRONICS, 1980, 16 (02) : 165 - 169
  • [6] HUNTER WR, 1985, SPECTROMETRIC TECHNI, V4, P63
  • [7] KAHN SD, UNPUB
  • [8] KAHN SM, 1990, IAU C, V115, P365
  • [9] EFFICIENCY MEASUREMENTS OF REFLECTION GRATINGS IN THE 100-300-A BAND
    MEEKINS, JF
    KOWALSKI, MP
    CRUDDACE, RG
    [J]. APPLIED OPTICS, 1989, 28 (07): : 1369 - 1377
  • [10] PAERELS FBS, COMMUNICATION