摘要:

Two‐dimensional (2D) carrier profiling is an important aspect of the characterization of ultra‐large‐scale integrated devices. Through a special measurement procedure and sample preparation it has been shown that the use of spreading resistance profiling (SRP) for this application is possible with 10–20 nm spatial resolution. Extension to the quantitative determination of a three‐dimensional profile appears to be possible. Higher spatial resolution has been achieved using transmission electron microscopy (TEM) based methods whereby chemical etching and electron irradiation are investigated. For these methods detection limits down to 5×1017cm−3have been determined. Based on the properties of SRP (sensitivity and quantification) and TEM (high spatial resolution, on‐chip application) both methods are found to be highly complementary for 2D carrier profiling.

ISSN:1071-1023    

DOI:10.1116/1.586373

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

Energy gap and carrier concentration are among the most important material parameters governing the electrical performance of AlGaAs/GaAs heterojunction devices. A novel technique for profiling aluminum mole fraction ratio and carrier concentration is presented which is based on point contact current voltage (PCIV) measurements. The method measures point contact voltages at a preselected current as a function of depth. A composition profile is then created by referring to appropriate calibration samples. The PCIV technique is rapid, inexpensive, and offers high spatial and depth resolution. Additionally, both the aluminum mole fraction ratio and the carrier concentration can be obtained sequentially from the same measurement. The application of this technique to several device structures of current interest is presented.

ISSN:1071-1023    

DOI:10.1116/1.586374

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

Measurements of electrically active dopant profiles in thin III–V semiconductor structures are critical to the development of high speed and optoelectronic devices. The point contact current voltage (PCIV) technique has previously been demonstrated to be a powerful method for the high spatial resolution carrier concentration profiling of III–V semiconductors, offering improved measurement range and resolution when compared withC‐Vmethods. For thin layers, the on‐bevel carrier concentration profile measured with the PCIV technique differs from the electrically active net dopant profile. These differences are due to carrier diffusion. Poisson analysis can account for the diffusion of the carriers away from the dopant atoms and provide a clearer picture of the dopant profile in the material. In this paper we demonstrate application of the Poisson equation to the interpretation of PCIV measurements on thin III–V semiconductor structures of current interest.

ISSN:1071-1023    

DOI:10.1116/1.586375

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

In this work we report on methodologies and procedures to obtain the doping profile of semiconductor homo‐ and heterostructure devices with ultra‐abrupt doping transitions at or near the surface of a device or test structure using capacitance–voltage measurement techniques. Novel methods to obtain the complete carrier distribution (or ‘‘spike’’) of structures containing single of multiple planar (also known as delta) doped layers will be addressed. Techniques to measure the true doping profile of abrupt step and staircase doped structures will also be discussed. Extensive numerical models and methods have been developed to accurately extract doping and carrier concentration profiles of traditional and two‐dimensional electron (or hole) gas devices. The analysis and acquisition techniques which have been developed are applicable to all group IV and III–V compound semiconductor devices containingp‐nhomojunctions or heterojunctions, Schottky or Mott barriers, or MOS or MIS barriers. General limitations imposed by Debye screening and specific considerations related to quantum mechanical carrier confinement will be discussed. Strategies to confirm the abruptness of the impurity doping or alloy composition transitions will also be addressed.

ISSN:1071-1023    

DOI:10.1116/1.586376

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

Application of the majority carrier corrected (MCC) dopant profiling technique described by Ziegler can be complicated by instrumentation, programming, and numeric analysis problems. A practical implementation of the MCC method is described which addresses these problems. The method has been implemented in a system based on the Keithley Package 82C–Vmeasurement system and was coded using HP‐BASIC 5.13. An automatic method for locating the region of validC–Vdata for doping profile analysis by using a limiting solution of Ziegler’s equations is described. Accurate, low‐noise differentiation of the 1/C2data (required for profile calculation) by use of Savitsky–Golay convolution is presented. Averaging, dose integration, and doping extrema are all calculated with the aid of a mouse‐driven plot interface. The software was written in a modular form which allows easy modification and reduced code development overhead.

ISSN:1071-1023    

DOI:10.1116/1.586378

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

The doping profile in semiconductors can be extracted very accurately fromC–Vmeasurements using the inverse modeling approach. This method requires very extensive numerical calculations which makes its practical implementation very difficult for process characterization purposes. To minimize the execution time of this technique a dynamic mesh algorithm has been developed. Using this algorithm the decrease in the calculation time of the doping profile parameters of over one order of the magnitude was obtained. The improved computational method was verified using simulation examples and experimental results for ion implanted metal–oxide semiconductor capacitors.

ISSN:1071-1023    

DOI:10.1116/1.586379

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

Traditional electrical doping profile extraction techniques fail for ultra‐shallow metal–oxide–semiconductor (MOS) doping profiles due to simplifications in the physical models or limitations in the analytical formulas. A method to overcome these problems is presented, based on the numerical extraction of doping profiles from capacitance–voltage (C–V) measurements without limiting approximations. The following steps are involved: measurement of the high and low frequencyC–Vcharacteristics of a MOS test structure; definition of an initial parametrized representation of the doping profile using analytical basis functions; determination of the interface trapped charge from the measuredC–Vcharacteristics; minimization of the difference between the calculatedC–Vcharacteristic, computed from the full one‐dimensional solution of Poisson’s equation, and the measuredC–Vcharacteristic, by optimizing the doping profile parameters. All computations are performed on an engineering workstation which can also control theC–Vmeasurements and data acquisition. The method is demonstrated for MOS structures with known doping profiles, interface trap densities, and measurement noise. Uniqueness, resolution, and sensitivity issues of the extracted doping profiles are also discussed.

ISSN:1071-1023    

DOI:10.1116/1.586380

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

The method of junction delineation with thickness fringes in selectively chemical etched transmission electron microscope cross sections is demonstrated on a few examples. Arsenic‐doped source and drain regions of metal‐oxide‐silicon transistors were delineated at a concentration level of about 1×1018cm−3both in the as‐implanted state and after 900 °C annealing. Calibration was performed with one‐dimensional secondary ion mass spectroscopy dopant profiles whereas process simulation was used to examine the experimental two‐dimensional results. The lateral extent of the dopant surface concentration at 1×1019cm−3under the transistor gate after 900 °C annealing corresponded to then+/ntransition region previously detected by scanning tunneling microscopy. Boron and arsenic junctions were simultaneously delineated in a bipolar transistor.

ISSN:1071-1023    

DOI:10.1116/1.586381

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

Two‐dimensional scanning tunneling microscope (STM) measurements on cleaved interdigitated shallowpnjunctions are presented. The two‐dimensional part of the junction is localized to within 30 nm. The cleaving of the junctions and the STM measurements are performed in ultrahigh vacuum (UHV). STM measurements onpnjunctions in air are also discussed. These measurements show that there is a relation between the magnitude of the tunneling current and the local impurity concentration of the sample. A qualitative model is presented that explains the observed effects.

ISSN:1071-1023    

DOI:10.1116/1.586382

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

Scanning tunneling microscopy (STM) is an electrically sensitive technique with atomic resolution, making it a viable candidate for use in shallow junction delineation. It has been demonstrated that STM can be used to distinguish betweenn‐ andp‐type semiconductors, yet the effects of STM tip and sample biases on the electronic structure of the silicon and, hence, on the tunneling current have not been extensively explored. A tunnel diode model has been proposed coupled with classical band bending to simulate these effects. The scanning of the tip across the junction was simulated using structure defining algorithms inpisces, a two dimensional device simulator. The tip electrode was moved incrementally across the silicon surface at a set height.pisceswas called at each new tip location to produce a new structure file. The Poisson equation was solved bypiscesat each tip location to determine band bending. Silicon surface potentials were extracted from the simulation and incorporated into the tunneling current calculations. Tunneling currents in the model depend on the density of empty states in the electron‐receiving material, on the density of filled states in the electron‐supplying material, and on the tunneling probability across the tip‐to‐semiconductor gap. The tunneling currents were then compared to experimental results.

ISSN:1071-1023    

DOI:10.1116/1.586383

出版商:American Vacuum Society    

年代:1992

数据来源: AIP