Real Time Characterization of Non-Ideal Surfaces and Thin Film Growth by Advanced Ellipsometric Spectroscopies
- PDF / 2,575,361 Bytes
- 16 Pages / 417.6 x 639 pts Page_size
- 28 Downloads / 209 Views
Materials Research Laboratory and Center for Thin Film Devices, The Pennsylvania State University, University Park, PA 16802. Department of Physics, Hanyang University, Ansan, KOREA.
ABSTRACT The development of multichannel ellipsometers with photodiode array-based detection systems has enabled real time spectroscopic ellipsometry (SE), a technique now being used widely to study surface modification and thin film growth. Multichannel ellipsometers based on the rotating-element design acquire spectroscopic data in parallel and thus offer advantages over other designs. The simplest rotating-element multichannel ellipsometers are constructed using a rotating polarizer or analyzer for polarization state modulation or detection. These configurations have a number of drawbacks, in particular, their insensitivity when measuring samples that reflect linearly polarized light and their susceptibility to errors when measuring samples having unrecognized non-idealities (e.g., macroscopic inhomogeneities) that generate a mixture of polarization states in the reflected beam. In this review, we describe recent advances in multichannel ellipsometry including (i) enhancement of the spectral range of the rotating-polarizer multichannel ellipsometer to 1.5-6.5 eV, (ii) adaptation of the rotating-compensator configuration to multichannel ellipsometry for studies of weakly absorbing and macroscopically inhomogeneous materials, and (iii) development of a dual rotating-compensator multichannel ellipsometer design for real time studies of optically anisotropic materials. As a recent example of the application of rotating-compensator multichannel ellipsometry, we describe analyses of (i) a macroscopicallyrough (textured) tin-oxide (Sn0 2 ) film on a glass substrate and (ii) the fabrication of the p-layer component of an amorphous silicon-based p-i-n solar cell on the textured SnO 2 film surface at a temperature of 200'C. INTRODUCTION
Over the past decade, multichannel spectroscopic ellipsometry (SE) has increased in popularity for real time studies of surfaces and thin film growth. The first applications of this technique were reported in 1990 and involved characterization of the electrochemical oxidation of metal surfaces, and the physical vapor deposition (PVD) of hard coatings [1,2]. The most recent applications presented at the last international conference on SE [3] included studies of the preparation of crystalline and amorphous semiconductor thin films by chemical vapor deposition (CVD) [4], plasma-enhanced CVD [5-7], and molecular beam and vapor phase epitaxy [8]. In addition, crystallization [9] and oxidation [10] of semiconductors, and PVD of metallic thin films [11] have been studied by multichannel SE, as described in other contributions to Ref. [3]. The trend toward multichannel SE reflects the recognition that, for all but the simplest surface modification and film growth problems, a spectroscopic capability is critical for unambiguous, quantitative analysis of the evolution of the optical properties, structure, and composi
Data Loading...
