Real-time Optical Monitoring of Epitaxial Growth Processes by p-Polarized Reflectance Spectroscopy

1995 ◽  
Vol 406 ◽  
Author(s):  
Nikolaus Dietz ◽  
Klaus J. Bachmannb
Keyword(s):  
Fine Structure ◽  
Epitaxial Growth ◽  
Real Time ◽  
Dielectric Function ◽  
Reaction Layer ◽  
Surface Reaction ◽  
Optical Probe ◽  
Reflectance Spectroscopy ◽  
Growth Processes ◽  
Polarized Reflectance

AbstractIn this paper we introduce a real-time optical probe technique, p-polarized reflectance spectroscopy (PRS), for the monitoring of epitaxial growth processes. GaP heteroepitaxy by pulsed chemical beam epitaxy (PCBE) is used as an example. PRS allows to follow the deposition process with submonolayer resolution, utilizing a fine structure that is superimposed to the interference oscillations in the reflected intensity. This fine structure is explained by the periodic alteration of the surface reaction chemistry under pulsed chemical precursor supply. In the case of epitaxial GaP growth, it is modeled for a four layer stack, including an ultra-thin surface reaction layer of periodically changing thickness do(t) and dielectric function εo(t) tied to the periodic surface exposure to tertiarybutyl phosphine (TBP) and triethylgallium (TEG) pulses, respectively. The imaginary part of the dielectric function, εO2, of this surface reaction layer can be determined directly from the distance of the inflection points in the fine structure, where the optical response to the first precursor pulse in the cycle sequence changes sign, from the closests interference minimum. The surface reaction kinetics can be studied by analyzing the decay time characteristic in the transients of the fine structure.

Multilevel Approaches Toward Monitoring and Control of Semiconductor Epitaxy

1996 ◽  
Vol 448 ◽  
Author(s):  
D. E. Aspnes ◽  
N. Dietz ◽  
U. Rossow ◽  
K. J. Bachmann
Keyword(s):  
Optical Properties ◽  
Real Time ◽  
Reaction Layer ◽  
Surface Reaction ◽  
Surface Region ◽  
Monitoring And Control ◽  
Time Analysis ◽  
Near Surface ◽  
Real Time Analysis ◽  
And Control

AbstractVarious optical techniques have been developed over the last few years to allow real-time analysis of regions of importance for semiconductor epitaxy, in particular the unreacted and reacted parts of the surface reaction layer (SRL) and the near-surface region of the sample. When coupled with emerging microscopic methods of calculating optical properties, these approaches will allow several levels of control beyond that which has been currently demonstrated.

Real-Time Monitoring of Epitaxial Processes by Parallel-Polarized Reflectance Spectroscopy

MRS Bulletin ◽  
1995 ◽  
Vol 20 (5) ◽  
pp. 49-55 ◽  
Author(s):  
Nikolaus Dietz ◽  
Klaus J. Bachmann
Keyword(s):  
Real Time ◽  
Low Cost ◽  
Normal Incidence ◽  
Optical Probe ◽  
Reflectance Spectroscopy ◽  
Industrial Applications ◽  
Monitoring And Control ◽  
Real Time Monitoring ◽  
Spectral Ellipsometry ◽  
Precise Control

The engineering of advanced micro-electronic circuits, optoelectronic devices, and integrated optical circuits requires precise control of the lateral dimensions and thicknesses of device features and of the stoichiometry and doping of epitaxial semiconductor regions. This is preferably achieved by real-time monitoring and control of the individual deposition and etching processes that constitute the processing sequence. The use of optical probe techniques for the real-time monitoring of etching and/or growth processes is favored because of their nondestructive character and their potential use in real-time feedback control. Some of these methods are ideal in monitoring the overall growth process and/or substrate temperature in industrial applications, requiring low cost and maintenance. For example, in situ reflectance-spectroscopy methods, such as dynamic optical reflectivity (DOS), spectral-resolved normal incidence reflectance spectroscopy (MRS), or pyrometric interferometry (PI), are successfully applied to various deposition processes and provide information on both the growth rate and the composition of the deposits. However, small changes in the reflectance (because of chemical interactions at the surface of the films with the reactants supplied from the vapor phase) are of the order of 10−3 to 10−4 and are hardly observable with normal-incidence reflectance techniques because of the high reflectivity of substrate/film interface, which is typically of the order of 40%–60% for many semiconductors.In order to increase the sensitivity to surface- and interface-related growth properties, alternative optical-observation methods such as reflectance difference spectroscopy (RDS), surface photoabsorption (SPA), and spectral ellipsometry (SE) have been developed.

Real-time Optical Monitoring of GaxIn1−xP/GaP Heterostructures on Silicon

1995 ◽  
Vol 406 ◽  
Author(s):  
N. Dietz ◽  
U. Rossow ◽  
D. E. Aspnes ◽  
N. Sukidi ◽  
K. J. Bachmann
Keyword(s):  
Fine Structure ◽  
Surface Reaction ◽  
Laser Light ◽  
Amplitude Ratio ◽  
Reflectance Spectroscopy ◽  
Chemical Beam Epitaxy ◽  
Optical Monitoring ◽  
Difference Spectroscopy ◽  
Combined Application ◽  
Reflectance Difference Spectroscopy

AbstractIn this paper we report the combined application of p-polarized reflectance spectroscopy (PRS), reflectance difference spectroscopy (RDS), and laser light scattering (LLS) to investigate the heteroepitaxy of GaxIn 1−xP/GaP on Si by pulsed chemical beam epitaxy (PCBE) with tertiarybutylphosphine (TBP), triethylgallium (TEG), and trimethylindium (TMI) precursors. Both, PRS and RDS follow the growth process with submonolayer resolution utilizing a periodic fine structure signal, which is caused by a periodic alteration of thickness and composition of an ultra-thin surface reaction layer during the periodic TEG and TBP exposure of the surface. After the transition from GaP growth to GaxIn 1−xP growth, the RDS oscillations are reoriented after about five precursor cycles in a new oscillation periodicity, where the response to the TBP pulse has the opposite direction. The ratio of the changes in the amplitudes of RDS signals as a response to TEG and TMI surface exposure is used to estimate the composition fo GaxIn 1−xP. The PRS fine structure is maintained after switching to GaxIn 1−xP growth with a separate feature for each TEG and TMI surface exposure. The amplitude ratio of these features changes during growth.

scholarly journals Real-time Characterization of the Optical Properties of an ultra-thin Surface Reaction Layer during Growth

1996 ◽  
Vol 441 ◽  
Author(s):  
N. Dietz ◽  
N. Sukidib ◽  
C. Harrisb ◽  
K. J. Bachmann
Keyword(s):  
Optical Properties ◽  
Fine Structure ◽  
Reaction Layer ◽  
Surface Reaction ◽  
Turning Points ◽  
Growth Conditions ◽  
Chemical Beam Epitaxy ◽  
Modulated Phase ◽  
Interference Oscillations

AbstractThe average optical properties of an ultra-thin surface reaction layer (SRL) during growth by pulsed chemical beam epitaxy (PCBE) can be quantitatively accessed by p-polarized reflectance spectroscopy (PRS), as demonstrated on the example of heteroepitaxial GaP growth. Under PCBE growth conditions, the surface of the substrate is exposed to pulsed ballistic beams of tertiarybutyl phosphine [TBP, (C4H9)PH2] and triethylgallium [TEG, Ga(C2H5)3]. The pulsed precursor supply causes a period in composition and thickness modulated SRL, monitored as a fine structure that is superimposed on interference oscillations, resulting from back reflection at the substratelayer interface with increasing layer thickness. The amplitude of this fine structure undergoes a period amplitude modulation and exhibits turning points at which the response to the first precursor pulse changes sign. The turning points can be characterized by the expression R4(Φmax)=R4(Φmin), which describes the maximal and minimal values of the temporally modulated phase factor in the SRL, using a four layer stack description. The positions of these turning points are not affected by the thickness of the SRL, which allows the computation of the average complex dielectric function of the SRL independent of its thickness. In the next step, the average thickness of the SRL can be extracted from the amplitude of the observed fine structure.

Real-Time optical Characterization and Control of Heteroepitaxial GaxIn1−xP Growth by P-Polarized Reflectance

1999 ◽  
Vol 591 ◽  
Author(s):  
N. Dietz ◽  
K. Ito ◽  
I. Lauko ◽  
V. Woods
Keyword(s):  
Reaction Kinetics ◽  
Real Time ◽  
Closed Loop ◽  
Surface Reaction ◽  
Ex Situ ◽  
Growth Surface ◽  
Organometallic Precursors ◽  
Surface Reaction Kinetics ◽  
And Control ◽  
Polarized Reflectance

ABSTRACTThe characterization and control of thin film growth processes requires improved methods of characterization and understanding of decomposition pathways and surface reaction kinetics under steady-state epitaxial growth involving organometallic precursors. In this contribution we present the application of p-polarized reflectance spectroscopy (PRS) for real-time monitoring and control of pulsed chemical beam epitaxy (PCBE) during low temperature growth of epitaxial Ga1−xInxP heterostructures on Si(001) substrates by PCBE, where the growth surface is sequentially exposed to organometallic precursors. During the pulsed precursor supply the surface reaction kinetics can be followed by analyzing a periodically in composition and thickness modulated surface reaction layer (SRL), which is captured in the PR-signals as a fine structure that is superimposed to the interference fringes caused due to the underlying growing film. The optical response is linked to the growth process via a reduced order surface kinetics (ROSK) model and integrated as a control signal in the implementation of filter and control algorithms for closed-loop controlled growth of epitaxial Ga1−xInxP heterostructures on Si(001) substrates. The control concept has been applied for thickness and compositional graded multi-heterostructure GaxIn1−xP epilayers and validated by ex-situ post-growth analysis, showing superior tracking of composition and thickness targets under closed loop controlled conditions compared to films grown using pre-designed source injection profiles (open-loop conditions).

A polycentric growth model of gallium arsenide epitaxial layers from the gas phase with simultaneous diffusion, adsorption and chemical reaction

1988 ◽  
Vol 53 (12) ◽  
pp. 2995-3013
Author(s):  
Emerich Erdös ◽  
Jindřich Leitner ◽  
Petr Voňka ◽  
Josef Stejskal ◽  
Přemysl Klíma
Keyword(s):  
Growth Rate ◽  
Gallium Arsenide ◽  
Epitaxial Growth ◽  
Gas Phase ◽  
Surface Reaction ◽  
Quantitative Description ◽  
The Other ◽  
Rate Equations ◽  
Impact Interaction ◽  
Partial Pressures

For a quantitative description of the epitaxial growth rate of gallium arsenide, two models are proposed including two rate controlling steps, namely the diffusion of components in the gas phase and the surface reaction. In the models considered, the surface reaction involves a reaction triple - or quadruple centre. In both models three mechanisms are considered which differ one from the other by different adsorption - and impact interaction of reacting particles. In every of the six cases, the pertinent rate equations were derived, and the models have been confronted with the experimentally found dependences of the growth rate on partial pressures of components in the feed. The results are discussed with regard to the plausibility of individual mechanisms and of both models, and also with respect to their applicability and the direction of further investigations.

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