Crystallinity Of poly-Si Films Research Articles

Formation of (100)-oriented large polycrystalline silicon thin films with multiline beam continuous-wave laser lateral crystallization

Low-temperature crystallization to (100)-oriented polycrystalline silicon (poly-Si) thin films is a key requirement for high-performance low-temperature poly-Si thin-film transistors (LTPS-TFTs). Biaxially (100)-oriented poly-Si thin films were formed by multiline beam continuous-wave laser lateral crystallization in single scans. By overlapping scanning, the (100) preferential orientation was stable and (100) silicon crystals were developed over a large area. The crystallinities of the poly-Si films were precisely characterized, especially by two-dimensional X-ray diffraction. It was found that the poly-Si thin films predominantly had (100)-surface-oriented crystals. The crystallinity of the laser-crystallized poly-Si films was dependent on the scanning speed and overlapping condition. The (100) poly-Si films were formed at scanning speeds below the threshold for lateral-crystallized silicon.

Control of grain size and crystallinity of poly-Si films on quartz by Al-induced crystallization

The crystalline properties of poly-Si films on quartz grown using Al-induced crystallization (AIC) were investigated. The orientation fraction and grain size were controlled by modulating the annealing temperature and sample thickness. The results confirmed the enhancement of (111)-orientation fractions and grain size by lowering the annealing temperature and reducing the thickness. The effects of both parameters, annealing temperature and thickness, on the growth process were investigated, as was the role of the Al layer. We successfully formed (111)-oriented grains up to 384 μm in size at a rate of 99% in a 50 nm-thick sample annealed at 400 °C. Furthermore, the real applications of AIC poly-Si as a growth template were demonstrated through silicon thin-film and nanowire formation.

Preparation of silicon thin films by intense pulsed ion-beam evaporation method with low temperature process

We have succeeded in preparing polycrystalline silicon thin films by the intense pulsed ion-beam evaporation method without impurities on substrates of silicon and quartz. Good crystallinity and high deposition rate were achieved without thermal processing such as heating the substrates. The crystallinity of poly-Si film has been improved by increasing the density of the ablation plasma. Since the lifetime of the ablation plasma, which was obtained by a pulsed ion beam with 50-ns pulse width, is of the order of 20 μs, the instantaneous deposition rate is in the region of cm/s. The crystallinity was increased by increasing the number of shots. The crystallization and the deposition rate of poly-Si thin films prepared on different substrate positions were investigated.

Room Temperature Preparation of Poly-Si Thin Films by IBE with Substrate Bias Method

Using intense pulsed ion beam evaporation technique, we have succeeded in the preparation of poly crystalline silicon thin films without impurities on silicon substrate. Good crystallinity and high deposition rate have been achieved without heating the substrate by using lEE. The crystallinity of poly-Si film has been improved with the high density of the ablation plasma. The intense diffraction peaks of poly-Si thin films could be obtained by using the substrate bias system. The crystallinity and the deposition rate of poly-Si thin films were increased by applying (-) bias voltage for the substrate.

Characteristics of polycrystalline silicon thin films prepared by pulsed ion-beam evaporation

Using the intense pulsed ion-beam evaporation method, we have succeeded in preparing polycrystalline silicon thin films without impurities on substrates of silicon and quartz. High crystallinity and deposition rate were achieved without heating the substrate. Since the lifetime of the ablation plasma, which was obtained by a pulsed ion beam with 50-ns pulse width, is of the order of 20 μs, the instantaneous deposition rate is in the region of cm/s. The crystallinity of poly-Si film has been improved by increasing the density of the ablation plasma, whereby the grain size of the film was found to be smaller.

Preparation of polycrystalline silicon thin films by pulsed ion-beam evaporation

Using the intense pulsed ion-beam evaporation technique, we have succeeded in the preparation of polycrystalline silicon thin films. Good crystallinity and high deposition rates have been achieved without substrate heating. The crystallinity of poly-Si film has been improved by increasing the density of the ablation plasma. The intense diffraction peaks and high density of poly-Si thin films can be obtained by biasing the substrate.

Characteristics of Polycrystalline Silicon thin Films Prepared by Pulsed Ion-Beam Evaporation

AbstractUsing intense pulsed ion-beam evaporation technique, we have succeeded in the preparation of polycrystalline silicon thin films on silicon substrate without impurities. Good crystallinity and high deposition rate have been achieved without heating the substrate. The crystallinity of poly-Si film has been improved with increasing the density of the ablation plasma. The intense diffraction peaks of poly-Si thin films can be obtained by using the substrate bias system. The crystallinity and the deposition rate of poly-Si thin films are increased by negative bias voltage for the substrate.

Effects Of Impurities on the Crystallization and Grain Growth of Polycrystalline Si Films

AbstractDevice-quality poly-Si films are used as the active material of poly-Si thin film transistors. Poly-Si films with high crystallinity, which have large grains and/or low intragranular defects, lead to a high device performance. The presence of O or C impurities in the deposited Si films can greatly affect the behavior of crystallization and grain growth of these films, and their resulting crystallinities. A substantial amount of O or C can be introduced in the films during deposition from residual gases in the deposition chamber. Control of base pressure during Si deposition, therefore, will be an important process parameter determining the crystallinity of these films. The effects of the base pressure on the crystallization and grain growth of deposited Si films were investigated using a high vacuum Chemical Vapor Deposition system. Lower base pressure decreases the deposition temperature for the amorphous/crystalline transition of as-deposited films. Crystallization of amorphously deposited films is also affected by base pressure. The kinetics of crystallization and crystallinities of poly-Si films after crystallization are substantially increased by reducing base pressure. Enhanced crystallization kinetics and film crystallinities can be explained by reduced inclusions of O or C impurities in Si films, thus enhancing the atomic mobility. The improved film crystallinity of poly-Si films leads to higher device performance of poly-Si TFT's.