Effect of Phosphorus Doping on the Young’s Modulus and Stress of Polysilicon Thin Films

2011 ◽  
Vol 1299 ◽  
Author(s):  
Elena Bassiachvili ◽  
Patricia Nieva
Keyword(s):  
Thin Film ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Average Stress ◽  
Phosphorus Concentration ◽  
Phosphorus Doping ◽  
On Chip ◽  
Deformation Tests ◽  
Phosphorus Doped ◽  
Dopant Source

ABSTRACTOn-chip MEMS (Micro Electromechanical Systems) characterization devices have been used to extract the Young’s modulus and average stress of polysilicon doped with phosphorus using thermal diffusion from a spin-on-dopant source. A customized fabrication process was developed and the devices were fabricated and tested. Resonant and static deformation tests were performed using microbridges. Information gathered from these experiments was combined to extract the Young’s modulus and residual stress of the thin film. Several doping concentrations, from undoped to 2.99×1020 phosphorus atoms/cm3 (4.148×10-4 Ω/cm), have been studied and it has been concluded that the Young’s modulus of phosphorus doped polysilicon with a chemical phosphorus concentration of 1.96×1020 atoms/cm3 (4.572×10-4 Ω/cm) increases by approximately 50GPa and the average stress of polysilicon with a phosphorus concentration of 2.99×1020 atoms/cm3 (4.148×10-4 Ω/cm) becomes more tensile by approximately 63 MPa relative to undoped specimens.

On-Chip Young’s Modulus Characterization of the Effect of Phosphorus Heavy Doping on Polysilicon Thin Films

2009 ◽  
Author(s):  
E. Bassiachvili ◽  
P. Nieva ◽  
A. Khajepour
Keyword(s):  
Thin Films ◽  
Young’S Modulus ◽  
Doping Concentration ◽  
Young's Modulus ◽  
Bottom Layer ◽  
Phosphorus Concentration ◽  
Mems Devices ◽  
Heavy Doping ◽  
On Chip

Information on material properties of structural thin films for MEMS fabrication is very limited. The small information available in the literature suggests that the Young’s modulus of structural thin films such as polysilicon can change up to 30% with heavy doping at room temperature. Accurate knowledge of these variations is critical for proper design as well as operation of MEMS devices, especially for applications that require them to be exposed to harsh environmental conditions. In this paper, devices for the on-chip characterization of the Young’s modulus of polysilicon as a function of the doping concentration conditions are presented. Analytical modeling has been performed to predict the change in the devices’ pull-in voltage as a function of doping concentration. The devices were fabricated using the PolyMUMPs process on two different polysilicon layers on the same chip separated by a layer of oxide. The top layer devices are heavily doped while the bottom layer devices are left lightly doped. The lightly doped devices serve as a reference, allowing some account for fabrication uncertainties in order to ensure consistent results. Devices for measuring in-plane stresses, out-of-plane stress gradients and specially designed resistor structures that account for the effect of contact resistance have also been fabricated to monitor these quantities while testing. The devices will be tested using a customized vacuum chamber to study the effect of phosphorus concentration on these structures.

Measurement of Young's Modulus and Poisson's Ratio of Thin Film by Combination of Bulge Test and Nano-Indentation

2008 ◽  
Vol 33-37 ◽  
pp. 969-974 ◽  
Author(s):  
Bong Bu Jung ◽  
Seong Hyun Ko ◽  
Hun Kee Lee ◽  
Hyun Chul Park
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Young’S Modulus ◽  
Poisson’S Ratio ◽  
Young's Modulus ◽  
Applied Pressure ◽  
Indentation Test ◽  
Poisson's Ratio ◽  
Bulge Test ◽  
Nano Indentation

This paper will discuss two different techniques to measure mechanical properties of thin film, bulge test and nano-indentation test. In the bulge test, uniform pressure applies to one side of thin film. Measurement of the membrane deflection as a function of the applied pressure allows one to determine the mechanical properties such as the elastic modulus and the residual stress. Nano-indentation measurements are accomplished by pushing the indenter tip into a sample and then withdrawing it, recording the force required as a function of position. . In this study, modified King’s model can be used to estimate the mechanical properties of the thin film in order to avoid the effect of substrates. Both techniques can be used to determine Young’s modulus or Poisson’s ratio, but in both cases knowledge of the other variables is needed. However, the mathematical relationship between the modulus and Poisson's ratio is different for the two experimental techniques. Hence, achieving agreement between the techniques means that the modulus and Poisson’s ratio and Young’s modulus of thin films can be determined with no a priori knowledge of either.

Determination of Mechanical Properties of Thin Film on Silicon Wafer

2003 ◽  
Author(s):  
Enboa Wu ◽  
Albert J. D. Yang ◽  
Ching-An Shao ◽  
C. S. Yen
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Thermal Expansion ◽  
Young’S Modulus ◽  
Silicon Wafer ◽  
Coefficient Of Thermal Expansion ◽  
Young's Modulus ◽  
Poisson Ratio ◽  
Bulk State

Nondestructive determination of Young’s modulus, coefficient of thermal expansion, Poisson ratio, and thickness of a thin film has long been a difficult but important issue as the film of micrometer order thick might behave differently from that in the bulk state. In this paper, we have successfully demonstrated the capability of determining all these four parameters at one time. This novel method includes use of the digital phase-shifting reflection moire´ (DPRM) technique to record the slope of wafer warpage under temperature drop condition. In the experiment, 1-um thick aluminum was sputtered on a 6-in silicon wafer. The convolution relationship between the measured data and the mechanical properties was constructed numerically using the conventional 3D finite element code. The genetic algorithm (GA) was adopted as the searching tool for search of the optimal mechanical properties of the film. It was found that the determined data for Young’s modulus (E), Coefficient of Thermal Expansion (CTE), Poisson ratio (ν), and thickness (h) of the 1.00 um thick aluminum film were 104.2Gpa, 38.0 ppm/°C, 0.38, and 0.98 um, respectively, whereas that in the bulk state were measured to be E=71.4 Gpa, CTE=23.0 ppm/°C, and ν=0.34. The significantly larger values on the Young’s modulus and the coefficient of thermal expansion determined by this method might be attributed to the smaller dislocation density due to the thin dimension and formation of the 5-nm layer of Al2O3 formed on top of the 1-um thick sputtered film. The Young’s Modulus and the Poisson ratio of this nano-scale Al2O3 film were then determined. Their values are consistent with the physical intuition of the microstructure.

Influence of annealing on microstructure & molecular orientation, thermal behaviour, mechanical properties and their correlations of uniaxially drawn iPP thin film

e-Polymers ◽  
2008 ◽  
Vol 8 (1) ◽  
Author(s):  
Sayant Saengsuwan
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Tensile Strength ◽  
Young’S Modulus ◽  
Thermal Behaviour ◽  
Annealing Time ◽  
Molecular Orientation ◽  
Young's Modulus ◽  
Crystal Thickness ◽  
Scanning Calorimetry

AbstractThe influence of annealing on the microstructure and molecular orientation, thermal behaviour and mechanical properties of uniaxially drawn iPP thin film was studied by wide-angle X-ray diffraction, differential scanning calorimetry and tensile testing, respectively. The correlations of mechanical and microstructural properties of annealed films were also examined. The transformation of smectic phase of iPP to the α-form was more pronounced with increasing annealing time and temperature. The true and apparent crystallinities and crystal thickness were strongly enhanced with annealing time and temperature. The relative molecular orientation tended to increase with annealing time. These results caused the significant improvement of modulus and tensile strength of the annealed films in both machine (MD) and transverse (TD) directions. The increases in MD-Young’s modulus and MD-tensile strength were well correlated with the increase in true crystallinity obtained in equatorial scans. Some relationship between the increase in crystal thickness and the increase in Young’s modulus in both MD and TD directions was also found.

Evaluation of Young's Modulus for Polymer Thin Film on Isotropic Substrate by ComplexV(z) Curve

2004 ◽  
Vol 43 (5B) ◽  
pp. 2920-2923 ◽  
Author(s):  
Masahiro Maebayashi ◽  
Tatsuro Matsuoka ◽  
Shinobu Koda ◽  
Ryuki Hashitani ◽  
Tomohiro Nishio ◽  
...  
Keyword(s):  
Thin Film ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Polymer Thin Film ◽  
Z Curve
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