Etching with a hard mask

In wet etching the resist is usually not consumed by the etchant, and the gravest danger is adhesion loss. This is dependent on priming, feature size, resist thickness and the chemical character of the resist. Generally, thicker resists are mechanically more stable. Interface stability is important for the etched profile because the etchant can easily propagate along the film resist interface. Photoresists are materials that combine photoac-tivity and mechanical thermal chemical stability, and,...

Chemical shrink of dark field structures

The resist thinning method does not work for dark field patterns any loss of linewidth will result in wider structures. A poor man's method of small DF structures is based on resist flow resist will flow when heated above glass-transition temperature. This flow will, under favourable conditions, make holes and trenches smaller in a controlled fashion. This method has been successfully used in contact hole scaling studies. A more advanced version for making narrow dark field patterns consists of...

Pinhole hole in a chrome

pin spot (extra chrome on a light field area). From the yield and reliability point of view not all defects are equal. Defect must be understood as a Figure 8.4 Mask defects defects smaller than the feature size will affect final dimensions and, therefore, current density, electric field and other device parameters. Redrawn after Skinner, J.G. et al., by permission of SPIE very broad term anything that prints on the wafer or changes critical dimension by more than 10 is counted as a defect....

Measurement of epitaxial deposition

Three measurements must be carried out on epitaxial wafers thickness, resistivity and surface quality. Surface quality is assessed first and foremost by optical inspection pyramids, mounds and hillocks scatter light, which can be detected by optical methods. Nomarski interference contrast microscope detects surface height differences and infrared depolarization reveals stresses. Laser scattering measures particles and microrough-ness. Optical methods are fast, and 100 of wafers are inspected....

Optical Lithography

Lithography work flow consists of the following major steps when viewed from the point of view of the wafer 1. Photosensitive film (photoresist) application The alternative view is that of information flow this will be discussed in Chapter 10 in conjunction with lithography simulation. Optical lithography is basically photography. The original image to be transferred, the photomask, which corresponds to the negative in photography, is set in a mask-aligner exposure tool. It is aligned to the...

Float zone FZ crystal growth

Silicon 110 Wafer Secondary Flat

If high purity or oxygen-free silicon is needed, float zone (FZ) crystal growth is used. In the FZ-method, a polysilicon ingot is placed on top of a single-crystal seed. The polycrystalline ingot is heated externally by an RF coil, which locally melts the ingot. The coil and the melted zone move upwards, and a single crystal solidifies on top of the seed crystal. The highest FZ-silicon resistivities are of the order of 20 000 ohm-cm, compared to 100 to 1000 ohm-cm for CZ. Because there is no...

Characterization of PVD films

PVD films, especially sputter-deposited films, can be modified by a number of parameters. System configuration and geometry come to play via target-substrate distance, base pressure gas phase impurities and power coupling scheme bias voltage and process parameters such as pressure and power affect the momentum of the impinging atoms and ions, and substrate temperature is important for desorption, diffusion and reactions. Collimated sputtering is a technique in which a mechanical grid is placed...

Introduction to Microfabrication

Director of Microelectronics Centre, Helsinki University of Technology, Finland John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex PO19 8SQ, England Email (for orders and customer service enquiries) cs-books wiley.co.uk Visit our Home Page on www.wileyeurope.com or www.wiley.com AH Rights Reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording,...

Failure analysis and reverse engineering

Analytical methods are needed not only during fabrication, but also after wafer processing has been completed. When circuits are found malfunctional, either in testing or after field return, the causes must be identified. Hard errors, that is, consistent failures are much easier to locate and to understand than soft errors, that is, the intermittent failures that may take place only under certain operating conditions for example above certain temperature or frequency . As in wafer-level...

A

SiO2 18 32 02 12-FEB 3 Oxthi 0.4236 SiO2 18 32 02 12-FEB 3 Oxthi 0.4236 0.00 0.20 0.40 0.60 0.80 1.00 1.20 Depth m 0.00 0.20 0.40 0.60 0.80 1.00 1.20 Depth m Figure 3.3 a 1D simulation ICECREM of arsenic 150keV energy and boron 50keV implantation into silicon, dose 1015 ions cm2 and b dry oxidation of BF2 implanted silicon 20keV, 1015 ions cm2 modified by the user, but default parameters are good for initial simulations and novice users. Simulation examples in Chapters 6, 13, 14 and 15 are...

Lithography metrology

Lithography produces test structures of itself. Test structures must include resolution structures with the same dimensions as the devices themselves, but also smaller and larger structures so that process robustness and linearity can be checked. Optical microscopy and scanning electron microscopy SEM are standard methods. Even when linewidths are below optical microscopy resolution, it is useful as an initial check for instance, resist adhesion loss, delamination and other gross errors can be...

Simulation of Microfabrication Processes

Microfabrication processes consist of tens or hundreds of steps that take weeks or months to complete, and therefore the learning cycles can easily become too long. Simulation is one way of shortening the learning cycles. Simulation accuracy is strongly dependent on the details of the process to be simulated, and even a simple simulator can be extremely valuable if it saves enough experimentation time and effort. Simulators can provide meaningful trend data and comparisons between different...