BSRF and MEMS activities

Futing YI, Institute of high energy physics, Beijing, China, 100039

1. Introduction of BSRF

As a part of BEPC project, the Beijing Synchrotron Radiation Facility (BSRF) was constructed almost in parallel with the BEPC and has been opened to the users since 1991. Currently, there are a total 9 beam lines and 11 experimental stations in operation at BSRF. The accumulated machine time for synchrotron radiation is about two and half months per year.

The main buildings of BSRF consists of two experimental halls and two laboratory buildings annexed to them respectively. The experimental halls are located at the 3rd and 4th quadrants of the storage ring separately.

There are a total of 7 SR source points in the storage ring: the bending magnets 3B1, 3B3 and 4B9; the wavelength shifter 1W1, 4W1 and 4W2 the hybrid permanent magnet wiggler 3W1. The 4W1 is a single period wavelength shifter with magnetic period length of 1.392m, peak field of 1.8T, and gap of 66mm. It shifts the critical energy to 5.8 KeV at 2.2 GeV of electron beam energy. The 3W1 is a 5 periods permanent magnet wiggler with magnetic period length of 30cm and peak field of 1.5 T. The critical energy is 4.8 KeV at 2.2 GeV of electron beam energy.

There are total of 13 beamlines and 14 experimental stations in operation currently in BSRF. Fig. 1 shows the layout of beamlines and stations.

Fig. 1, the layout of beamlines and stations at BSRF

1W1A beamline is introduced to Diffuse Scattering Station for X-ray Huang diffuse scattering, power diffraction and high resolution diffraction. 1W1B with energy range of 4-22KeV is extracted to XAFS station. 4W1A is a high intense wiggler beamline to X-ray Fluorescence Station for physics, chemistry, biomedicine, geology, materials science, archeology and so on. 4W1B with a white X-ray is designed for Topography Station mainly used for X-ray phase contrast image, micro-structures of weakly-absorbing materials. 4B9B is designed for Photoemission Spectroscopy Station to do the research of electronic states and surface structures. 4B9A is a beamline with the energe range of 4-10keV for Small Angle X-ray Scattering Station and X-ray Diffraction Station. 4W2 is designed for High Pressure Research Station. 3B1A and 3B1C are designed for X-ray Lithography Station with nano X-ray lithography of nano LIGA and IC device and deep X-ray lithography of LIGA process. 3B1B beamline with the wavelenth range of 120nm to 500 nm is designed for VUV Spectroscope Station. 3B3 and 3W1B are designed for Soft X-ray Station to do the research of soft X-ray optics, calibration of soft X-ray detector.

2. X-ray lithography at BSRF

X-ray lithography is one of the most powerful tools to fabricate the structures with very high aspect ratio for LIGA, MEMS, nano LIGA and IC device. The structures, made by X-ray lithography, may have the height of several millimeters and very high aspect ratio over 100 for LIGA process and MEMS, and also can be fabricated with very high resolution of 25nm for nano MEMS and IC device.

X-ray lithography for IC device started in 1989 at the foundation of BSRF by cooperating with the Institute of Micro Electrons. The LIGA process has been developed at BSRF since 1994, including the mask fabrication, deep X-ray lithography, electroplating. Polyimide film is used as the mask membrane with thickness of 10-20µm, and SU8 structure as the primary mold for gold electroplating with thickness of 10-20µm. PMMA and SU8 are resist materials for deep X-ray lithography, Fig. 2 shows the PMMA structures with 88 aspect ratio of 5µm width and 440µm height. Nickel and copper are electroplating materials for micro motor, EDM structure, gripper and so on, Fig. 3 shows a nickel structure with 44 aspect ratio of 10µm width and 440µm height.

Fig.2, the PMMA structures with 88 aspect ratio Fig. 3, nickel structures with 44 aspect ratio.

3. The applications of LIGA and MEMS at BSRF

Many structures and devices are made by LIGA process and MEMS for the applications at BSRF by cooperating with other institutes, including micro structures for Electro Discharge Machine, pin structure for molecular mold, gold array structures for biochip, channel structures in glass for capillary electrophoresis, micro stepping motor, Gabor and Fresnel zones for X-ray focus, micro gripper, optical encode, and so on.