Low-stress sputtered chromium–nitride hardmasks for x-ray mask fabrication

Abstract

We have developed low-stress chromium nitride ͑CrN͒ films as hardmasks for x-ray absorber etching. The stress in the CrN films is 3 MPa and its distribution ͑gradient͒ is less than 10 MPa in a 25ϫ25 mm area. In addition, the CrN film is electrically conductive ͑1.4 ⍀/ᮀ͒. We have fabricated 0.10 m line-and-space patterns in 0.4-m-thick tantalum germanide using a 75-nm-thick CrN hardmask. The results demonstrate that a sputtered CrN film is an excellent hardmask material for x-ray mask fabrication.

Growth of single-crystal CrN on MgO(001): Effects of low-energy ion-irradiation on surface morphological evolution and physical properties

“…CrN has also been shown to possess high wear 4,5 and corrosion resistance, 6 to provide improved system adherence as an interfacial layer between diamond films and steel, 7 and to offer potential for use in phase-shift masks for photolithography 8 and etchresistant hardmasks for x-ray absorber patterning. 9 Reported physical properties of polycrystalline CrN x layers, typically deposited by reactive sputtering or arc evaporation, vary dramatically with growth parameters. [10][11][12][13][14] Resistivities, for example, range over more than six orders of magnitude from 3ϫ10 2 to 6ϫ10 8 ⍀ cm [15][16][17][18] and hardness values for CrN x vary from 13 to 31 GPa.…”

Recent progress in 1×x-ray mask technology: Feasibility study using ASET-NIST format TaXN x-ray masks with 100 nm rule 4 Gbit dynamic random access memory test patterns

“…1-mm-thick Si wafer is the starting substrate, upon which a 3-m-thick SiC film is deposited by lowpressure chemical vapor deposition. 45 Next, a 10-nm-thick CrN film for use as an etch stop, a 350-nm-thick TaBN film for the absorber, and 40-nm-thick CrN films as a hardmask 26 are successively deposited by sputtering. Then, back etching is carried out with a solution of HNO 3 and HF.…”

“…The main issues in x-ray mask fabrication are: ͑1͒ 1ϫmagnification and ͑2͒ the delineation of patterns on a thin membrane. In this regard, various processes and materials have been researched, namely, a subtractive membrane processes, 20,21 low-stress x-ray absorbers, [22][23][24][25] hardmasks, 26 resists, 19,21 silicon carbide ͑SiC͒, 27 and diamond. 28 -30 A highperformance EB mask writer, the EB-X3, suitable for PXL has been developed by NTT under an Association of SuperAdvanced Electronics Technologies ͑ASET͒ program.…”

Etching processes and characteristics for the fabrication of refractory x-ray masks

“…1,2 Amorphous TaSi films also exhibit the stress properties necessary for implementation as refractory x-ray mask absorbers. 5 At the IBM Microelectronics Division Advanced Mask Facility, x-ray masks are fabricated in a pilot line using TaSi absorbers with SiON hardmasks. 4 Chromium and chromium nitride films are also being considered as hardmasks for tantalum-based absorbers on x-ray masks.…”