Low pressure chemical vapour deposition at quasi-high flow

A new chemical vapour deposition (CVD) technique is presented. It is especially advantageous for the deposition of compound materials. The technique improves the uniformity and reproducibility of the deposition. The economical use of gaseous reactants is improved by a factor varying between 5 and 20. This is important in the case of expensive metal-organic CVD methods. The method consists in the manifold repetition of the following sequence: evacuation, filling and deposition in a horizontal tube reactor. The filling time of 50 ms is short compared with the deposition period 1 s.\ud \ud The advantages of the method are demostrated with results for the deposition of undoped, phosphorus-doped and boron-doped silicon and SiO2.\u

Determination of 2D implanted ion distributions using inverse radon transform methods

Two methods are presented for the experimental determination of 2D implanted ion distribution resulting from implantations with a line source into amorphous targets. It is shown that the relation between the 2D distribution and the depth profiles resulting from tilted angle implantations is described by the Radon transformation. The inverse transformation has been applied to accurately measured depth profiles. The first method uses a digitization of the 2D distribution and the second method uses a parameterized function for the 2D distribution. The methods are tested for a 400 keV boron implantation in an amorphous layer of silicon. The experimental obtained 2D distributions are compared with a TRIM Monte Carlo simulation. A good agreement between experiment and simulation is observed

Polycrystalline Silicon as a Diffusion Source and Interconnect Layer in FL Realizations

Boron-doped polycrystalline silicon is applied as a diffusion source for the p-type regions of I2L devices. The polysilicon also serves as a conductive level which requires no contact windows in the p-type regions. Compared to conventional processing a higher fan-out, size reduction, and a greater layout flexibility are reported

Two methods to improve the performance of Monte Carlo simulations of ion implantation in amorphous targets

Two methods are described for improving the results of a Monte Carlo technique used to simulate the transport of energetic ions in amorphous targets in two dimensions. The target considered is a homogeneous monolayer. The Monte Carlo technique used is based on the TRIM program. The first method relies on the fact that some calculated data can be used more than once. The second method relies on the fact that a point source results in a rotation-symmetric ion distribution. To study the behaviour of the two methods a smoothness indicator was defined. It is a measure of the distance of a simulation result from the ideal result, i.e., the result based on an infinite number of ion trajectories. This indicator showed that a CPU time reduction of a factor of 80 was achieve

Strongly asymmetric doping profiles at mask edges in high energy ion implantation

The application of high-energy ion implantation is restricted by an asymmetric doping profile at the mask edges. As a result, buried interconnect cannot easily be formed. Moreover, the holding voltage and threshold voltage of CMOS-processes with retrograde wells may be strongly affected by this asymmetry. It arises from the 7° wafer tilt, which is frequently used to avoid channeling, even in the case of nearly perpendicular (82-85°) mask edges. On the mask side, which is incoming to the ion beam, a trunk to the surface has experimentally been observed. According to two-dimensional Gaussian and advanced Monte Carlo simulations, the doping concentration in this trunk is about 20% of the maximum concentration in the case of a 85° mask angle. The simulations predict the experimental results fairly well. The asymmetry effect of high energy ion implantations can also be visualized in photoresist by means of a damaged regio

VIPMOS-A novel buried injector structure for EPROM applications

A buried injector is proposed as a source of electrons for substrate hot electrons injection. To enhance the compatibility with VLSI processing, the buried injector is formed by the local overlap of the n-well and p-well of a retrograde twin-well CMOS process. The injector is activated by means of punchthrough. This mechanism allows the realization of a selective injector without increasing the latchup susceptibility. The p-well profile controls the punchthrough voltage. The high injection probability and efficient electron supply mechanism lead to oxide current densities up to 1.0 Å.×cm-2. Programming times of 10 ¿s have been measured on nonoptimized cells. The realization of a structure for 5-V-only digital and analog applications is viable. A model of the structure for implementation in a circuit simulator, such as SPICE, is presente

Manual hyperinflation of intubated and mechanically ventilated patients in Dutch intensive care units--a survey into current practice and knowledge

BACKGROUND: In the daily bedside routine of the intensive care, potentially hazardous interventions that lack evidence need critical consideration. Therefore we examined current practice and knowledge of basic principles of manual hyperinflation (MH) in intubated and mechanically ventilated patients among intensive care unit nurses in the Netherlands. METHODS: A written survey method was used, questionnaires were sent to ICU nurses specialised in mechanical ventilation in 115 Dutch hospitals. The questions related to following domains: (1) demographics; (2) use of MH; (3) presumed benefits; (4) essential elements of the MH procedure; (5) equipment and safety. RESULTS: The response rate was 77%. From responding ICUs the majority (96%) stated they performed MH; 27% as a daily routine procedure, 69% performed MH on indication only. MH was mainly performed by ICU nurses. Half of ICUs reported to have a MH guideline available. Improved oxygenation and better removal of sputum were presumed benefits of MH. While slow inspiration and rapid expiration are considered to be essential elements of MH procedures, the majority of respondents stated to use rapid inspiration and slow expiration. CONCLUSIONS: This survey indicates that MH is widely used as an important item of airway management. Importantly, there is no uniformity in the performance of the procedure. Before definitive research can be developed, standards for the MH procedure should be establishe