Model correction for the formation of amorphous silicon by ion implantation

The critical dose at which an implanted amorphous layer in silicon is formed cannot be explained by a previous energy independent model. An energy dependent correction to this model can explain our ESR data as well as other data. The correction is most important for light ions.     

A mammographic phantom to measure mean glandular dose by thermoluminescent dosimetry

We have designed a phantom to evaluate mean glandular dose (MGD) as part of the regulatory dosimetry control for mammographic equipment. The phantom is constituted by TLD-100 thermoluminescent dosemeters (TLDs) inserted within semicircular plates of acrylic. Different groups of TLDs are used to determine entrance surface air kerma and half-value layer (HVL). Calibration of both tasks has been performed using a Senographe 2000D system and an ionization chamber. The phantom has been tested in five clinical systems. The HVL and MGD obtained by this method agree, on average, within 3%, with those from standard procedures based on the use of ionization chambers. The phantom MGD measurements have a combined uncertainty better than 10% (k = 1).     

Measurement of photoneutron doses in and out of high-energy X-ray beam of a SATURNE-20 medical linear accelerator by ECE polycarbonate detectors

Photoneutron contaminations in and out of high energy X-ray beams of the medical linear accelerator SATURNE 20 (CGR) of the Radiotherapy Department of Omeed Hospital in Isfahan, Iran, have been determined using 250 μm polycarbonate (PC) dosimeters, in strips or in sheets, processed by electrochemical etching (ECE) using specially designed ECE chambers to etch larger sheets. A two dimensional or topographical distribution of neutron contamination was also determined in a full size beam. The neutron dose equivalents (Hn) in the beam of 18 MV X-rays at 80 cm FSD were determined to be linear functions of X-ray dose equivalents (Hx) up to 1400 cSv. The distribution of the Hn at different X-ray doses showed bell-shape profiles with maxima at the isocenter. The ratios of dose equivalents of neutrons to those of X-rays increased as the field size increased having values of 0.22%, 0.28%, 0.31% and 0.37% for field sizes of 10×10, 20×20, 30×30, and 40×40 cm² respectively. Although such neutron dose equivalents can be corrected for patient treatment, it can cause radiation protection problems for workers where the design of the facility is not well planned.     

A study on the real-time radiation dosimetry measurement system based on optically stimulated luminescence

The optically stimulated luminescent (OSL) radiation dosimeter technically surveys a wide dynamic measurement range and a high sensitivity.Optical fiber dosimeters provide capability for remote monitoring of the radiation in the locations which are difficult-to-acoess and hazardous.In addition.optical fiber dosimeters are immune to electrical and radio-frequency interference.In this paper,a novel remote optical fiber radiation dosimeter is described.The optical fiber dosimeter takes advantage of the charge trapping materials CaS:Ce, Sm that exhibit OSL.The measuring range of the dosimeter is from 0.1 to 100 Gy.The equipment is relatively simple and small in size,and has low power consumption.This device is suitable for measuring the space radiation dose and also can be used in high radiation dose condition and other dangerous radiation occasions.     

The Dependence of IRSL Intensity on Radiation Dose for Samples of Chlorides Contained in Feldspars

The intensity of the luminescence generally increases with radiation dose and measurement of these phenomena can be used to characterise the degree of dependence on beta doses. In this study, in order to test whether this is a significant problem on the optically stimulated luminescence (OSL) studies, the radiation dose response of the OSL signal from samples of chlorides contained in feldspars have been investigated by irradiating the samples with beta doses. The infrared-emitting diodes were used with a wavelength of (880±80) nm, and an IRSL (infrared stimulated luminescence) intensity parametres, m, was described and found m = 1±0.03.     

193nm光刻曝光系统的现状及发展

投影曝光工艺是集成电路制造过程中的关键环节，曝光系统的工艺水平已成为衡量微电子制造技术的重要标志。重点介绍了目前193nm光刻设备曝光系统的发展现状和趋势，以及为提高曝光质量所采用的相关分辨率增强技术；通过分析曝光系统的构成和其中的关键技术，探讨了国内研制相关曝光设备所面临的挑战。     

曝光系统离焦对平面全息光栅衍射波前的影响

波前像差是衍射光栅的重要技术指标，它直接影响光栅的分辨率。由光致刻蚀剂记录两束相干光干涉条纹是制作全息光栅的关键步骤。为了提高全息光栅曝光系统调整精度、减小离焦、降低光栅的衍射波前像差，从离焦对反射球面准直镜的准直光平行度的影响程度出发，分析了准直光平行度对全息光栅衍射波前像差的影响。理论分析和数值模拟结果表明，准直镜调整误差直接决定全息光栅衍射波前像差大小。以3种不同刻线密度光栅为例，得出了准直镜调整误差的允许变化范围。     

沉积物中石英ESR测年功率饱和效应的初步研究

介绍了几组沉积物中石英ESR功率饱和效应的基础实验情况,认为在用石英进行ESR测年时,微波功率的选择是一个重要参数,它直接影响累积剂量(AD)的求取,从而严重影响测年结果。在某些特定的地质环境下(如黄土,海洋沉积物),采用比较高的微波功率,可从沉积物石英的E'心得到较老沉积物(大于50万年)可信的ESR年代。     

Exposure Simulation Model for Chemically Amplified Resists

In this study, after Dill’s model is discussed for transmittance and refractive indices of the non-chemically amplified resists, G- and I-line novolak resists, and the chemically amplified resists, a modification of Dill’s model as a new exposure model is introduced. The simulation results obtained using this new model with the multi-thin film interface method and the Berning theory have shown a good matching to the experimental data. Also, the simulated transmittance change due to the exposure parameters are used to analyze the influence of the coefficients on the transmittance.     

用反差确定电子束曝光剂量与刻蚀深度的关系

 为了精确地确定电子束曝光剂量与刻蚀深度间的关系，根据抗蚀剂的灵敏度曲线，采用反差经验公式来确定剂量与刻蚀深度间的关系。选用正性抗蚀剂PMMA进行曝光实验，将计算值进行曲线拟合，得到的关系曲线与实验结果基本相符。当剂量在20~35 μC/cm²间时，实验值与计算值间的差值最小，说明当剂量在此范围内时该方法能够更加精确地确定剂量与刻蚀深度间的关系。采用该方法节省了实验时间，提高了刻蚀效率。