The Impact of Anneal on Electromigration of Copper Interconnect and the Optimized Anneal Technology Study

The theoretical and experimental work is executed for study the impact of anneal on the grain size, electromigration (EM) reliability of copper (Cu) interconnect system, and subsequently find the optimized anneal condition. EM accelerated failure tests are carried on the Cu interconnect samples with 0.2μm line width, which are produced at different anneal conditions. It is shown that anneal can lead the grains to grow to become larger, and lessen the EM diffuse path. As a result, the EM diffuse active energy (Ea) of Cu interconnect is enhanced, and the ability against the EM of Cu interconnect is improved. By comparing the EM character of Cu interconnects produced at different anneal conditions, results can be obtained as below: the anneal time should be maintained 40 minutes at least in order to achieve fully anneal and excellent ability against the EM; the anneal temperature should be set about 350°C approximately, because high temperature (beyond 400°C) anneal can induce the other reliability issues, which will have a strong negative impact on the EM reliability. The results in this paper are significance for Cu interconnect technology optimize and are beneficial to improve the EM reliability of the Cu interconnect system.

Effect of Anneal Time on Photoelectric Properties of SnS:Ag Thin Films

SnS and Ag films were deposited on glass substrates by vacuum thermal evaporation successively, and then the thin films were annealed at 260°C in N2 for different times (60min, 120min, 180min) in order to investigate the influence of annealing time on the silver-doped SnS (SnS:Ag) films. The obtained films annealed at different times are polycrystalline SnS with orthogonal structure, and the crystallites in the films are exclusively oriented along the {111} direction. With the increase of annealing time, the uniformity and crystallization of the films are improved, the carrier concentration and mobility of the films first rise and then drop, whereas their resistivity and direct bandgap energy Eg show the contrary trend.

Threshold Voltage Shift Variation of a-Si:H TFTs With Anneal Time

Hydrogenated amorphous silicon (a-Si:H) thin-film transistors (TFTs) are widely used in many areas and the most important application is in active matrix liquid crystal display. However, the instability of the a-Si:H TFTs constrains their usability. These TFTs have been annealed at higher temperatures in hope of improving their electrical performance. But, higher anneal temperatures become a constraint when the TFTs are grown on polymer-based flexible substrates. This study investigates the effect of anneal time on the performance of the a-Si:H TFTs on PEN. Thin-film transistors are annealed at different anneal times (4 h, 24 h, and 48 h) and were stressed under different bias conditions. Sub-threshold slope and the off-current improved with anneal time. Off-current was reduced by two orders of magnitude for 48 hours annealed TFT and sub-threshold slope became steeper with longer annealing. At positive gate-bias-stress (20 V), threshold voltage shift (∆Vt) values are positive and exhibit a power-law time dependence. High temperature measurements indicate that longer annealed TFTs show improved performance and stability compared to unannealed TFTs. This improvement is due to reduction of interface trap density and good a-Si:H/insulator interface quality with anneal time.

EFFECT OF ANNEALING ON THE GIANT MAGNETO-IMPEDANCE OF CO-BASED WIRES

The giant magnetoimpedance (GMI) effect in Co 75 Fe 4.2 Si 8 B 12 Nb 0.8 melt extraction wires annealed in a vacuum furnace at 450°C holding for 10min, 20min, 25min, 30min and 40min, respectively, is investigated. Strong GMI effect is observed at a typical frequency of 37MHz. The observation on the GMI effect indicates that the anisotropy field dominated by the anneal treatment is vital to the GMI ratio △Z/Z(%) and its field sensitivity. The improvement on GMI effect when anneal time is less than 20min is ascribed to the stress release, decreased anisotropy field and increased permeability. The decrease of GMI effect when anneal time is over 25min results from nanocrystalline phase grow up inducing the crystalline anisotropy field increase. Suitable annealed wires possess large GMI ratio (855%) and little anisotropy field achieving high field sensitivity to 151%/ Oe . These results indicate these Co -based melt extraction wires are excellent for using in novel field sensors applications.

Ti/AlNi/W Ohmic Contacts to P-Type SiC

Improved AlNi-based ohmic contacts to p-type 4H-SiC have been achieved using low energy ion (Al+) implantation, the addition of a thin Ti layer, and a novel two-step implant activation anneal process. Resistivities sometimes as low as 5×10−5 Ω-cm2 were reached by doping the surface region of lightly p-doped 4H-SiC epilayers via low energy Al+ implantation. Acceptor activation was achieved by annealing the samples with a 1400+1700°C two-step sequence in an Ar atmosphere, which also yielded improved surface morphology when implanted samples were capped with photo resist during the anneals. In this study, Ti/AlNi/W contacts on implanted layers were compared to Ti/AlNi/Au contacts. Even though the resistivities are higher than those of the Ti/AlNi/W system, the reduced anneal temperature, 650°C for Ti/AlNi/Au compared to 950°C for Ti/AlNi/W implies that Ti/AlNi/Au is a promising stacking configuration. Furthermore, the effects of a longer 30 minute anneal time at 600 − 700°C, in atmospheric pressure Ar ambients was observed. Namely, the 2 minute annealing cycle used for the Ti/AlNi/W study resulted in higher anneal temperatures before ohmic characteristics were seen. This same anneal time was not sufficient for the Ti/AlNi/Au samples, whereas increasing the cycle time to 30 minutes resulted in ohmic behavior at a much lower temperature. Increasing the anneal time however, had little or no impact on reducing the required anneal temperature of the Ti/AlNi/W.