四探针技术测量薄层电阻的原理及应用

对四探针技术测试薄层电阻的原理进行了综述,重点分析了常规直线四探针法、改进范德堡法和斜置式方形Rymaszewski法的测试原理,并应用斜置式Rymaszewski法研制成新型的四探针测试仪,利用该仪器对样品进行了微区(300μm×300μm)薄层电阻测量,做出了样品的电阻率等值线图,为提高晶锭的质量提供了重要参考.     

The use of a metalorganic compound for the growth of InP-epitaxial layers

InP epitaxial layers have been grown by the pyro-lysis of a new metalorganic compound, a trimethyl-indium trimethyl-phosphene adduct. The formation of unwanted polymer products during epitaxial growth could be avoided in this way. The layers were grown at 500°C with a growth rate of about 1 μmh_-1. Net carrier concentrations of n≏5-10^l5cm^-3 could be achieved.     

Multiple internal reflection spectroscopy: a sensitive non-destructive probe for interfaces and nanometric layers

A multiple internal reflection (MIR) infrared monitoring system based on the two prism coupling geometry has been developed for the measurement of silicon wafer surfaces and interfaces. The new set-up we describe here increases the sensitivity of IR spectrometry by at least two orders of magnitude. It is shown that the MIR technique allows chemical analysis of ultra thin layers, surface contaminations and embedded interfaces in a non-destructive way.     

Roller nanoimprint lithography for flexible electronic devices of a sub-micron scale

This paper proposes a new concept of a RNIL (roller nanoimprint lithography) system. The system does not require the roll stamp that is necessary in the conventional RNIL system, and it easily transfers patterns from a hard stamp to a flexible substrate. Generally, hard stamps such as Si wafers are of a circular shape. While imprinting with a hard stamp using the RNIL system, the pressing force of the press roller in the system varies as the length of the contact line between the circular-type hard stamp and the roller changes. In this study, the contact force profile is presented and is then implemented. Micro- and nano-scale patterns are transferred from Si stamps onto thin and flexible PC (polycarbonate) substrates. Then performance of the system is the evaluated by SEM images.     

Investigation of iridium as a gate electrode for deep sub-micron CMOS technology

The physical and electrical properties of an Ir/SiO₂/Si stack were evaluated for advanced gate electrode application. The thermal stability of the stack was studied on MOS capacitors annealed at temperatures between 500 and 1000 °C in N₂ ambient for 30 s followed by forming gas anneal (FGA) at 420 °C for 20 min. The work function of iridium, found to be 4.9 eV, is stable up to 900 °C, making it a good candidate as PMOS electrode. In addition, no evidence was found for any chemical reaction at the interface between Ir and SiO₂.     

The removal of nanoparticles from sub-micron trenches using megasonics

The removal of nanoparticles form patterned wafers is one of the main challenges facing the semiconductor industry. In this paper, the removal of 100 and 200 nm polystyrene latex (PSL) particles from silicon trenches was investigated. Red fluorescent PSL particles were utilized in the cleaning experiments and were counted using fluorescent microscopy. All the experiments were conducted in a single wafer megasonic tank using deionized water (DI). Trenches were fabricated with widths varying from 200 nm to 2 μm and with an aspect ratio of one. Results show that removal of particles from larger trenches is faster compared to smaller trenches and that megasonics power is more important in the removal process than cleaning time.     

Longitudinal stitching of sub-micron periodic fringes on a roller

In this work, a servo-assisted system for fabricating sub-micron gratings on a roller-type mold is developed. The fringes are produced by optical interference lithography and have period of about 800 nm. A supporting and precision manipulating system for roller mold is established so that seamless longitudinal fringe stitching can be achieved. Analysis of the measurement system and stitching error are given. Also, beam-steering concept is introduced into this system for correction of relative motion between the roller and the optical system. Exposure experiment is initiated on a 50 mm-diameter roller. The grating structure is directly and indirectly examined by microscopic equipments.     

Experimental study of WL-CSP reliability subjected to a four-point bend-test

This article deals with the reliability of WL-CSP subjected to a four-point bend-test according to the JEDEC standard and the repeatability of this test. The evaluation of the test repeatability shows a 5% variation on the characteristic Weibull parameter η. Two dedicated failure detection methods are used: with an event detector and with data acquisition and no difference are observed. Parameters considered are pre-load magnitude and loading frequency. PCB strain due to pre-load is measured and its effect on the product reliability is evaluated. Based on these measurements a pre-load value is defined. It is also shown that a frequency of 3 Hz modifies the studied package lifetime.     

Simulation and measurement of multiplication in thin-filmelectroluminescent devices with doped probe layers

When a single voltage pulse is applied to an electroluminescent (EL) device after previous illumination, the current through the phosphor layer will normally not be homogeneous, but increase from the cathodic side-where the electrons tunnel from-to the anodic side, due to multiplication. The positive charges that remain after the multiplication process cause a positive space charge that has been observed in various experiments and influences the efficiency. In this paper a simple numerical model is proposed for the calculation of charge transfer and light emission, in the case that multiplication takes place during a voltage pulse after previous illumination     

Application of charge pumping technique for sub-micron MOSFET characterization

In this paper, charge pumping technique for MOSFET interface characterization will be reviewed. The basic principles of charge pumping technique will be elaborated and its evolution as an excellent tool for a thorough characterization of MOSFET interface properties will be illustrated. Published results regarding the applicability of charge pumping technique for a study of sub-micron MOSFET interface and its degradation under various electrical stress conditions and radiation will be analyzed. The effect of geometric components on charge pumping current as well as the recent reports of single interface trap characterization in sub-micron MOSFETs will be described. The application of charge pumping technique at cryogenic temperatures and in other MOS based devices will also be included.     

The loop antenna as a probe

The properties of circular and square loop antennas as probes for measuring the magnetic field are investigated. The response of an electrically small loop to the magnetic and the electric components of a given electromagnetic field is determined theoretically for singly- and doubly-loaded loops in terms of suitably defined constants. A system error ratio is defined as a measure of the ability of a given probe to discriminate against the effects of the electric field. An experimental procedure for measuring loop sensitivities in the elliptically polarized near field of a quarter-wave monopole is described. Experimental and theoretical results are compared. It is concluded that very large errors are possible when a singly-loaded loop is used to measure magnetic fields unless its diameter is less than0.01lambda. The doubly-loaded probe may be used with comparable accuracy when its diameter is as large as0.15lambda.     

A dual-frequency rain profiling method without the use of a surface reference technique

A method to estimate the drop size distribution (DSD) parameters for dual-frequency radar observations that does not rely on the surface echoes is proposed. The method adjusts the estimates of attenuation factor at the surface iteratively until these estimates retrieve the reflectivity factors that are equal to the original measured reflectivity factors. In this iteration method, the backward-recursion equations are used as a main routine to calculate the DSD parameters for each range bin. The estimates of attenuation factor at the surface are obtained from these DSD parameters. The method is applied to the airborne radar data from the CaPE experiment in 1991. The comparison between the results derived from the surface reference technique and those derived from the proposed method is presented and discussed.     

The effect of dynamic design processing for yield enhancement inthe fabrication of deep sub-micron MOSFET's

With the downscaling of microelectronic devices, tighter process control and more elaborate fabrication equipment need to be complemented by process correcting techniques if good quality and high yields are to be expected. Dynamic design processing-a forward correcting technique by which some recipe values are recalculated during manufacturing-is such a technique. In this paper the effect of dynamic design processing on deep sub-micron MOSFET's is presented. The results show that a parametric yield improvement in excess of 25% over conventional manufacturing can be achieved     

Patterning issues for the fabrication of sub-micron memory capacitors' electrodes

This paper describes some of the key issues associated with the patterning of metal electrodes of sub-micron (especially at the critical dimension (CD) of 0.15 μm) dynamic random access memory devices. Due to reactive ion etching lag, the Pt etch rate decreased drastically below the CD of 0.20 μm and thus K-th storage node electrode with the CD of 0.15 μm could not be fabricated using the Pt electrodes. Accordingly, we have proposed novel techniques to surmountly-the above difficulties. The Ru electrode cannot for the stack-type structure is introduced and alternative multischemes based on the introduction of the concave-type selfstructure upto using semi-Pt or Ru as an electrode material are outlined respectively.     

The use of contrast enhancement layers to improve the effective contrast of positive photoresist

The analytic solution of Babu and Baruch to the dynamic bleaching problem is used to evaluate the merit of contrast enhancement layers in photolithography. A CEL performance criterion is defined as the effective gain in resist system contrast. This gain is evaluated as a function of the CEL and resist parameters. The performance gain is maximized if the product of CEL sensitivity and resist "dose to clear" exceeds one. Universal curves are also given for the evaluation of the CEL transmission function. It is found that nonbleachable absorption in the CEL degrades the performance if its magnitude exceeds a few percent of the bleachable component.     

Limitations on the range of measurements of sheet resistivity of shallow diffused layers for profiling by the four-point-probe technique

It is found that the standard four-point probe resistivity measurement and stripping technique used for measuring impurity profile in diffused semiconductor layers can provide reliable information only if certain limitations are carefully observed. To get the actual surface concentration for profiling, it has been found necessary to predetermine the appropriate range of current and voltage. Approximate ranges for studying phosphorus and boron in silicon are reported in this paper. The phosphorus profile obtained by this technique by successive measurement of sheet resistivity after anodic oxidation and stripping distinctly shows a kink and tail structure obtained without annealing.     

The long string as a field probe

We show how a long string can be used to probe the incident field across the target zone of a radar cross section (RCS) test range. The string may be stretched horizontally from wall to wall, or vertically from floor to ceiling. One end of the string is fixed and the other end is moved by an actuator mounted in the wall or ceiling. The resulting motion changes the angle of the string with respect to the incident-field direction, during which time the coherent radar echo is recorded as a function of the string angle. The coherent signal-as-a-function-of-angle data are then transformed to the cross-range domain using the fast Fourier transform (FFT), whence we obtain a chart of the incident field amplitude as a function of cross-range distance. Numerical examples are presented that show how variations in the incident field influence the string echo. A sample of experimental data shows that the processed data are readily interpreted.     

深亚微米SRAM电流感应电路的分析和优化*

本文对随机掺杂浮动效应下传统的电流感应电路的可靠性做了定量的分析。主要考虑了晶体管尺寸、控制信号的下降时间和特定晶体管的阈值电压三方面对电流感应电路可靠性的影响。在这个基础上,我们做了最终的优化来提高电流灵敏放大器的可靠性。在90纳米工艺下,仿真结果显示最终优化后的电流感应电路的失败率能够比优化前减少百分之八十,而延时只是稍微增加一点。     

Analysis and optimization of current sensing circuit for deep sub-micron SRAM

A quantitative yield analysis of a traditional current sensing circuit considering the random dopant fluctuation effect is presented.It investigates the impact of transistor size,falling time of control signal CS and threshold voltage of critical transistors on failure probability of current sensing circuit.On this basis,we present a final optimization to improve the reliability of current sense amplifier.Under 90 nm process,simulation shows that failure probability of current sensing circuit can be reduced by 80%after optimization compared with the normal situation and the delay time only increases marginally.