&lt;title&gt;Mechanical and structural properties of in-situ doped PECVD silicon carbide layer for post-processing surface micromachining&lt;/title&gt;

This paper details the development of low-stress, heavily-doped polycrystalline 3C-SiC films suitable for microelectromechanical systems applications. The films were deposited on 100 mm-diameter silicon (Si) and silicon dioxide (SiO 2 )-coated Si wafers in a large-volume, low-pressure chemical vapor deposition furnace using dichlorosilane (DCS) (SiH 2 Cl 2 ) and acetylene (C 2 H 2 ) as precursors and ammonia (NH 3 ) as the dopant source gas. The effects of NH 3 and deposition pressure on the deposition rate, film residual stress and electrical resistivity were studied. Deposition parameters optimized for a combination of resistivity and residual stress yielded an average resistivity of 0.02 cm and a residual tensile stress of 59 MPa as measured using wafer-scale methods. X-ray photoelectron spectroscopy indicated that the nitrogen concentration in the films was less than 0.5 at%. Variations in the flow rate of NH 3 did not affect the surface roughness of the films, but changes in deposition pressure had an obvious effect on the surface roughness.

Section: The Effect Of Nitrogen Doping On Sic Film Propertiessupporting

confidence: 68%

Doped polycrystalline 3C–SiC films with low stress for MEMS: part I. Deposition conditions and film properties

Trevino

Mehregany³

et al. 2014

“…Therefore it finds its place in many fields such as optoelectronics [4], microelectronics [5] and MEMS [1,3]. Due to its excellent properties, such as high mechanical strength, high thermal conductivity, ability to operate at high temperatures, resistance to harsh environment and extreme chemical inertness in a number of liquid electrolytes [6], it has great potential in micro electro mechanical systems (MEMS). The properties of PECVD amorphous SiC can be controlled over a wide range (for example, 1.8 eV to 3 eV for the optical bandgap and −400 MPa to 400 MPa for stress) by changing the deposition conditions, especially the ratio of the gases used [1], and also by in situ doping.…”

Section: Selection Of Materialsmentioning

confidence: 99%

“…Thin films of amorphous SiC deposited by PECVD despite the low deposition temperature preserve good mechanical properties and these properties can be controlled through varying deposition parameters [7]. The influence of silane flow rate and LF (low-frequency part of total RF power) component on layer stress is presented in figures 1 and 2, respectively [6].…”

Section: Selection Of Materialsmentioning

confidence: 99%

Fabrication of a CMOS compatible pressure sensor for harsh environments

Pakula

Yang

Pham

et al. 2004

The fabrication and characteristics of CMOS compatible absolute pressure sensors for harsh environments are presented in this paper. The sensor which was fabricated using post-processing surface micromachining consists of 100 circular membranes with a total capacity of 14 pF. PECVD SiC was used due to its good mechanical properties, but since SiC has high resistivity, aluminium layers were used for electrodes. The stiction problems were avoided by using polyimide PI2610 as a sacrificial layer. The pressure sensors were fabricated and the change of capacitance over full pressure range, 5 bar, was 3.4 pF.

“…After stripping of the masking layer the structural layer is deposited. PECVD silicon carbide layers [5], undoped or in situ doped, are deposited on the polyimide and patterned using a similar dry etch process as described in the previous section. Furthermore, metals such as titanium and aluminium have also been deposited (by rf sputtering) on the polyimide sacrificial layer and patterned by dry etching in Cl-based plasma.…”

Section: Deposition Of the Structural Layer And Sacrificial Etchingmentioning

confidence: 99%

Polyimide sacrificial layer and novel materials for post-processing surface micromachining

Bagolini

Pakula

Scholtes

et al. 2002

108

We present a low-temperature post-processing module, utilizing polyimide as a sacrificial layer and novel materials such as PECVD SiC and metals (sputtered aluminium and titanium) as structural layers. The use of spin-on polyimide allows an all-dry final release step overcoming stiction problems often encountered in wet sacrificial etching processes. The spinning and curing procedure has been tailored to the specific needs of the IC-compatible post-process module. For the patterning of the polyimide, thin films of aluminium, PECVD silicon oxide or silicon carbide are employed as a mask layer. Anisotropic etching of the mask film and of the polyimide layer is accomplished by RIE. After patterning the structural layer, sacrificial etching of the polyimide is done using an isotropic dry etch process in high-density oxygen plasma. An underetch rate of 4 μm min−1 is achieved. Compatibility with different structural materials is tested and test structures are designed and realized in a fully post-processing surface micromachining module.