Linewidth control effects

With any resist, the ideal conditions for obtaining high resolution and good linewidth control are a flat surface and a thin resist (<400 nm). The flat surface means that the resist will have very little variation in thickness and, as a result, there will be little variation in resist linewidth. However linewidth variations stemming from resist thickness variations do occur when lines traverse a step as a result of exposure and development effects. Indeed, such... 

Effects of Developer Concentration on Linewidth Control in Positive Photoresists... 

The images obtained with Microposit 351 (5 1) dilution with no added NaCl, 0.5 moles NaCl, and 1.0 moles of NaCl are shown in Figures 3, 4, 5. It can be seen that the required relative exposure time dropped substantially from 640 msec, to 390 msec. When 0.5 moles of NaCl was added to the developer, the linewidth control across the wafer was unchanged. The prediction from equation(3) can be seen to be qualitatively confirmed. A similar effect was observed with Microposit 351 at the 3.5 to 1 concentration. The reduction in photospeed at higher concentration of NaCl remains unexplained. However, it suggests that the key to optimum developer speed is Na+ ion concentration and optimum contrast is obtained primarily by adjustment of the 0H ion concentration. 

Figure 6.2 Effect of immobilization chemistry on the linewidth of compound s in solution. 1D 1 H spectra of the aromatic protons of phosphotyrosine (pY) are shown with the fitted linewidth. From top to bottom, pY in solution, in the presence of Actigel ALD, streptavidin Sepharose, Zn-IDAA Sepharose> Zn-NFA Sepharose, Zn-NFA silica and controlled-pore glass beads (for comparison).

The effect of quantum interference on spontaneous emission in atomic and molecular systems is the generation of superposition states that can be manipulated, to reduce the interaction with the environment, by adjusting the polarizations of the transition dipole moments, or the amplitudes and phases of the external driving fields. With a suitable choice of parameters, the superposition states can decay with controlled and significantly reduced rates. This modification can lead to subnatural linewidths in the fluorescence and absorption spectra [5,10]. Furthermore, as will be shown in this review, the superposition states can even be decoupled from the environment and the population can be trapped in these states without decaying to the lower levels. These states, known as dark or trapped states, were predicted in many configurations of multilevel systems [11], as well as in multiatom systems [12],... 

From experiments on several different kinds of films, including films of a-Si H to be discussed in the next section, Thomas et al (1978) suggest that the qualitative behavior of the temperature-independent component of the linewidth as a function of spin density Ns is as exhibited in Fig. 17. At low spin densities the asymptotic behavior is controlled by g-tensor effects. The narrowing with increasing is thought to be caused by dipolar spin-flip interactions or exchange effects, and the increase at high Ns is attributed to the normal dipolar interaction as expressed in Eq. (3). 

At first sight, quantitative analysis by NMR might be expected to be highly accurate and broadly applicable since the extinction coefficient for NMR is unity. In practice, it is found that the best accuracy achievable in extensive studies of proton NMR of known mixtures is +1%. Results at this level of accuracy require very careful attention to the selection of the experimental parameters such as pulse width, pulse repetition time, and nOe effects and the availability of calibration mixtures. For analysis the accuracy is commonly poorer, l-5%, because of the reduced S/N ratio and the variation of nOe contributions with molecular structure and field strength. Errors of +10% or more are not uncommon in quantitative analyses especially when conducted by inexperienced operators. In proton NMR, linewidth variation is an underappreciated issue. Careful control of experimental parameters, and the use of calibration mixtures are minimum requirements for accurate analyses and accuracies of + 0.5% have been achieved by experts. 

---