Recombination of H(3+) and D(3+) ions with electrons

Flowing-afterglow measurements in decaying H3(+) or D3(+) plasmas suggest that de-ionization does not occur by simple binary recombination of a single ion species. We find that vibrational excitation of the ions fails to provide an explanation for the effect, contrary to an earlier suggestion. Instead, we suggest that collisional stabilization of H3** Rydberg molecules by ambient electrons introduces an additional dependence on electron density. The proposed mechanism would permit plasma de-ionization to occur without the need for dissociative recombination by the mechanism of potential-surface crossings

In-situ Sensing using Mass-Spectrometry and its use for Run-to-Run Control on a

Abstract. A 300 amu closed-ion-source RGA (Leybold-Inficon Transpector 2) sampling gases directly from the reactor of an ULVAC ERA-1000 cluster tool has been used for real time process monitoring of a W CVD process. The process involves H 2 reduction of WF 6 at a total pressure of 67 Pa (0.5 torr) to produce W films on Si wafers heated at temperatures around 350° C. The normalized RGA signals for the H 2 reagent depletion and the HF product generation were correlated with the W film weight as measured post-process with an electronic microbalance for the establishment of thin-film weight (thickness) metrology. The metrology uncertainty (about 7% for the HF product) was limited primarily by the very low conversion efficiency of the W CVD process (around 2-3%). The HF metrology was then used to drive a robust run-to-run control algorithm, with the deposition time selected as the manipulated (or controlled) variable. For that purpose, during a 10 wafer run, a systematic process drift was introduced as a -5°C processing temperature change for each successive wafer, in an otherwise unchanged process recipe. Without adjustment of the deposition time the W film weight (thickness) would have declined by about 50% by the 10 th wafer. With the aid of the process control algorithm, an adjusted deposition time was computed so as to maintain constant HF sensing signal, resulting in weight (thickness) control comparable to the accuracy of the thickness metrology. These results suggest that in-situ chemical sensing, and particularly mass spectrometry, provide the basis for wafer state metrology as needed to achieve run-to-run control. Furthermore, since the control accuracy was consistent with the metrology accuracy, we anticipate significant improvements for processes as used in manufacturing, where conversion rates are much higher (40-50%) and corresponding signals for metrology will be much larger

Color-Tunable Eu(3+) and Tb(3+) co-doped nanophosphors synthesis by plasma-assisted method

With increasing health consciousness, Y₂O₃‐based rare earth nanophosphors are considered as promising luminescent complexes for bio‐applications. In the present study, an atmospheric pressure plasma‐electrochemical technique is demonstrated for the synthesis of Eu³⁺/Tb³⁺ single‐doped or co‐doped Y₂O₃ nanophosphors from merely an aqueous solution of the corresponding rare earth nitrite salts. Systematic experiments were performed to prepare (Y₁‐x‐yEuxTby)₂O₃ nanophosphors of various Tb³⁺ and Eu³⁺ ratios (x:y = 1:0, 2:1, 1:1, 1:2, and 0:1), with the ultimate goal to achieve the colour tunability by simply adjusting the dopant compositions. Results indicated successfulness synthesis of crystalline Eu/Tb single‐doped and co‐doped Y₂O₃ nanophosphors with Tb³⁺ and Eu³⁺ ions being uniformly incorporated into the Y₂O₃ host matrix. The generated products showed apparent downshift behaviour under ultraviolet irradiation, and characteristic spectral excitation and emission bands were detected by the photoluminescence measurement. Furthermore, by adjusting the relative composition ratios of the terbium and europium ions, the emission colours were shown to be regulated to a large extent. The demonstrated process can be characterized as simple, versatile and environmentally‐friendly, featuring great flexibility in colour tunability, and therefore can present a considerable interest for emerging nanofabrication applications.LiangLiang Lin, XinTong Ma, Sergey A. Starostin, SiRui Li, Volker Hessel, Jie Shen, ShaoMing Shang, and HuJun X