Investigation of the Young’s Modulus and the Residual Stress of 4H-SiC Circular Membranes on 4H-SiC Substrates

Abstract

The stress state is a crucial parameter for the design of innovative microelectromechanical systems based on silicon carbide (SiC) material. Hence, mechanical properties of such structures highly depend on the fabrication process. Despite significant progresses in thin-film growth and fabrication process, monitoring the strain of the suspended SiC thin-films is still challenging. However, 3C-SiC membranes on silicon (Si) substrates have been demonstrated, but due to the low quality of the SiC/Si heteroepitaxy, high levels of residual strains were always observed. In order to achieve promising self-standing films with low residual stress, an alternative micromachining technique based on electrochemical etching of high quality homoepitaxy 4H-SiC layers was evaluated. This work is dedicated to the determination of their mechanical properties and more specifically, to the characterization of a 4H-SiC freestanding film with a circular shape. An inverse problem method was implemented, where experimental results obtained from bulge test are fitted with theoretical static load-deflection curves of the stressed membrane. To assess data validity, the dynamic behavior of the membrane was also investigated: Experimentally, by means of laser Doppler vibrometry (LDV) and theoretically, by means of finite element computations. The two methods provided very similar results since one obtained a Young’s modulus of 410 GPa and a residual stress value of 41 MPa from bulge test against 400 GPa and 30 MPa for the LDV analysis. The determined Young’s modulus is in good agreement with literature values. Moreover, residual stress values demonstrate that the fabrication of low-stressed SiC films is achievable thanks to the micromachining process developed.

Failure Strength Weibull Analysis of 4H-SiC Die through a 3-PB test

“…All the three distributions are consistent with the value of 244±15 GPa for the Young Modulus of the SiC die. However, the determined value differs from the ideal values reported in the literature [18] of 410 GPa or over 500 GPa [19] [20]. It should be considered that the determined Young module is an effective quantity.…”

Thermal and Mechanical Properties of Amorphous Silicon Carbide Thin Films Using the Femtosecond Pump-Probe Technique

“…Previous research shows that the Young’s moduli of 3C-SiC, 4H-SiC, single-crystal α -SiC(001), and single-crystal β -SiC(111) are 280–350 GPa [ 17 ], 410 GPa [ 18 ], 499 ± 2 GPa, and 440 ± 16 GPa [ 19 ], respectively. PECVD-grown a-SiC usually possesses a lower Young’s modulus, in the range of 88–310 GPa [ 4 , 17 , 20 , 21 , 22 , 23 ].…”

Process Optimization of Via Plug Multilevel Interconnections in CMOS Logic Devices

“…The resistivity of each film is shown in Table 1, and the deposition conditions are shown in Table 2. The resistivity was obtained by depositing 5000 Å of plasma-enhanced tetraethylorthosilicate (PETEOS) on the bare wafer, 200 Å of IMP Ti [34,35], 100 Å of CVD TiN, and 300 Å of IMP TiN [34], and measuring the sheet resistance using an Omnimap [36][37][38][39]. The resistivity of each film is shown in Table 1, and the deposition conditions are shown in Table 2.…”