Phase shift effects of radio-frequency bias on ion energy distribution in continuous wave and pulse modulated inductively coupled plasmas

A retarding field energy analyzer(RFEA) is used to measure the time-averaged ion energy distributions(IEDs) on the substrate in both continuous wave(CW) and synchronous pulse modulated radio-frequency(RF) inductively coupled Ar plasmas(ICPs).The effects of the phase shift θ between the RF bias voltage and the RF source on the IED is investigated under various discharge conditions.It is found that as θ increases from 0 to π,the IED moves towards the low-energy side,and its energy width becomes narrower.In order to figure out the physical mechanism,the voltage waveforms on the substrate are also measured.The results show that as θ increases from 0 to π,the amplitude of the voltage waveform decreases and,meanwhile,the average sheath potential decreases as well.Specifically,the potential drop in the sheath on the substrate exhibits a maximum value at the same phase(i.e.,θ = 0) and a minimum value at the opposite phase(i.e.,θ = π).Therefore,when ions traverse across the sheath region above the substrate,they obtain less energies at lower sheath potential drop,leading to lower ion energy.Besides,as θ increases from π to 2π,the IEDs and their energy widths change reversely.     

双频容性耦合等离子体密度径向均匀性研究

利用自主研制的全悬浮双探针, 对影响双频容性耦合等离子体径向均匀性的因素进行了研究. 发现低频功率、放电气压和放电间距对径向均匀性有明显影响. 合适的低频功率、放电气压及较大的极板间距可以得到更均匀的等离子体. 采用与实验相同的放电参数, 利用改进的二维流体模型进行理论模拟, 得到了不同极板间距下径向离子密度分布, 并和实验测量结果进行了比较, 两者的变化趋势基本符合. 关键词： 双频容性耦合等离子体 径向均匀性 全悬浮双探针 二维流体模型     

近代物理实验系列化教学模式探索

近代物理实验对培养学生动手能力和创新能力具有重要作用。如何才能更好地发挥近代物理实验课的作用,是值得从事该课程教学的教师深入思考的问题。本文针对系列化实验内容的设计,以及教学内容、教学方法和预习及考核机制进行改革探讨。在近代物理实验的教学中实施系列化实验教学模式,收到了较好的教学效果。     

基于ATLAS语言的航空自动测试系统的设计与实现

在简要介绍ATLAS语言的基础上,结合某型航空自动测试系统的研制,详细介绍了基于ATLAS语言的航空自动测试系统的组成及特点.     

加快成果交流为促进中国化学学科的发展与应用而拼博——办好学术期刊庆祝中国化学会成立六十周年

在全党和全国人民努力贯彻小平同志南巡讲话精神,加快改革开放步伐、集中精力把经济建设搞上去的热潮中,迎来了中国化学会成立六十周年。1982年9月中国化学会曾在其诞生地——南京举行了隆重的国际学术活动庆祝它的五十诞辰,至今已整10年了。10年来     

体部伽玛刀联合热化疗治疗中晚期肝癌25例临床观察

目的探讨利用体部伽玛刀联合全身热化疗和微量泵化疗对中晚期原发性肝癌进行综合治疗的疗效。方法入院后经检查无全身热疗及化疗禁忌症晚期肝癌患者25例,全身热疗时予氟尿嘧啶1g、羟基喜树碱10mg、奥沙利铂100mg;以后予奥沙利铂100mg/d,8d,静脉滴注;热化疗后第2d起予氟尿嘧啶0.25g/d,14d;羟基喜树碱2mg/d,9d。热化疗3d后进行体部伽玛刀治疗,50～65%的等剂量曲线包绕计划靶区PTV,单次剂量3.2～4.0Gy,10～12次,总剂量为36～44Gy。其中化疗泵治疗间隔2周重复,共4～6周期;全身热疗1～3次,于每次化疗第1天进行。热化疗及伽玛刀治疗结束后分别观察不良反应和近期疗效。结果部分缓解(PR)20例;1年局部病变无进展率为56%(14/25)。1年生存率为76%(19/25),2年生存率40%(10/25)。全身热疗中6例出现下肢或腹部局部皮肤红斑,2例出现小水泡;肝脏急性不良反应Ⅰ级1例。结论伽玛刀联合全身热化疗治疗肝细胞癌安全可靠,有利于提高疗效。     

双轮平衡车的设计与研究

本文基于STM32单片机,并采用陀螺仪等元器件,PID算法实现双轮平衡车的设计,实现小车直立行走.双轮平衡车小车采用MPU6050六轴陀螺仪传感器作为基本原件设计出姿态检测装置,小车的倾斜角等由陀螺仪数据和加速度计数据耦合,再通过PID算法使小车保持直立状态和实现车身控制等一些任务,实现了负重状态下小车的自主平衡.     

Fundamental study towards a better understanding of low pressure radio-frequency plasmas for industrial applications

Two classic radio-frequency (RF) plasmas, i.e., the capacitively and the inductively coupled plasmas (CCP and ICP), are widely employed in material processing, e.g., etching and thin film deposition, etc. Since RF plasmas are usually operated in particular circumstances, e.g., low pressures (mTorr-Torr), high-frequency electric field (13.56 MHz-200 MHz), reactive feedstock gases, diverse reactor configurations, etc., a variety of physical phenomena, e.g., electron resonance heating, discharge mode transitions, striated structures, standing wave effects, etc., arise. These physical effects could significantly influence plasma-based material processing. Therefore, understanding the fundamental processes of RF plasma is not only of fundamental interest, but also of practical significance for the improvement of the performance of the plasma sources. In this article, we review the major progresses that have been achieved in the fundamental study on the RF plasmas, and the topics include 1) electron heating mechanism, 2) plasma operation mode, 3) pulse modulated plasma, and 4) electromagnetic effects. These topics cover the typical issues in RF plasma field, ranging from fundamental to application.     

双频容性耦合等离子体相分辨发射光谱诊断

采用相分辨发射光谱法, 对双频容性耦合纯Ar和不同含O₂量的Ar-O₂混合气体放电等离子体的鞘层激发模式进行了探究. 在射频耦合电源上极板的鞘层区域处观察到两种电子激发模式: 鞘层扩张引起的电子碰撞激发模式和二次电子引起的电子碰撞激发模式; 并发现这两种激发模式均受到低频射频电源周期的调制. 在纯Ar放电等离子体中, 两种激发模式的激发轮廓相似; 而在Ar-O₂混合气放电等离子体中, 随着含O₂量的增加, 二次电子的激发轮廓变弱. 此外, 利用相分辨发射光谱法对不同含O₂量的Ar-O₂混合气放电下Ar的 750.4 nm谱线的平均低频电源周期轴向分布进行了研究, 得到了距耦合电源上极板约3.8 mm处为双频容性耦合射频等离子体的鞘层边界. 关键词： 双频容性耦合等离子体 等离子体鞘层 发射光谱