Intrinsic stress and stress gradients at the SiO2/Si interface in structures prepared by thermal oxidation of Si and subjected to rapid thermal annealing

Abstract

Articles you may be interested inInherent interface defects in thermal (211) Si / SiO 2 : 29 Si hyperfine interaction AIP Conf.This paper reports on a study of the intrinsic stress and strain in thin films ofSi0 2 prepared by the thermal oxidation of crystalline silicon. We focus on the relationship between the inhomogeneity of thin-film properties and the thermal history of the oxide film, including both film growth and thermal annealing. We show that this film can be inhomogeneous in the sense that oxide formed initially at the silicon-silicon dioxide (Si/Si0 2 ) interface has been annealed at the growth temperature for the time required for film growth, whereas newly formed oxide at the growth interface has not been annealed for any appreciable period. We demonstrate that thermal annealing cannot completely remove the thickness dependence in the strain induced by the mismatch between the molar volumes of silicon and silicon dioxide at the growth interface, subject to constraints introduced by the chemical bonding structure at that interface. Based on laser-beam deflection and photoreflectance measurements, we show that there is always a substantial residual intrinsic interfacial stress, and that is independent of the growth temperature, and thermal annealing. A time scale for describing thermal relaxation of stress and strain profiles is given by the ratio of process time to the viscoelastic relaxation time at the processing temperatures.

Analysis of geometrical effects on the behavior of transverse and longitudinal modes of amorphous silicon compounds

“…Model 2 has been reported to reproduce the spectra of amorphous materials such as SiO 2 and SiN x successfully. 4,5 The two main options of the simulation program are ͑i͒ determination of dielectric functions from reflectance or transmittance measurements ͑by a fitting procedure͒ and ͑ii͒ simulation of reflection and transmission spectra for any multilayered system under various experimental conditions.…”

“…For instance, in thin SiO 2 films, intrinsic stresses are often measured from the peak frequency of the transverse-optical ͑TO͒ and longitudinal-optical ͑LO͒ stretching modes of the Si-O bond ͑TO 3 and LO 3 , respectively͒ by using models applicable to the short-range order of the amorphous structure. [1][2][3] Moreover, the composition and microstructure of nonstoichiometric silicon oxides, nitrides, oxynitrides, and other silicon compounds are frequently measured from the peak frequency, shape, and other features of the infrared bands. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] Evaluation of the hydrogen content ͑or other impurities͒ in deposited or grown amorphous layers are routinely determined from the intensity and position of their respective infrared resonances.…”

Non-Contact Technique for Determining the Mechanical Stress in thin Films on Wafers by Profiler

“…Figure 4 shows that at edges wafer increases the stresses. The average value mechanical stresses on the work area substrate is -210 MPa, which corresponds to the order of magnitude [2,3,7,10].…”

“…For example, by making structure of heat treatment the purpose of minimization stress [7,12]. To determine nature of occurrence of mechanical stresses carried out comparative analysis of stress values and value of thermal stress calculated in TCAD software.…”

“…Therefore, it is important to evaluate and control the amount of stress, not only to avoid damage to device [2,5], but also to improve product specifications. The existing techniques for determination of mechanical stresses are based on wafer deformation (use of Newton rings, Stoney formula [2,6]) or connected with measurement of lattice parameters (Raman spectroscopy [7], X-ray diffractometry [8,9], transmission electron microscopy).…”