This paper investigates the CD correction methods to obtain better across-wafer CD uniformity (CDU) after etching for logic devices which have various types of patterns. CD optimization methods are evaluated for contact holes with a diameter of 46 nm after etching. CD optimization methods with PEB temperature and exposure-dose mapping on a wafer at a lithography step are examined in detail. Simulation study using a full physical resist model is done to analyze the detailed effects of each optimization method. The results of the simulation show that better optical and chemical image gives better CD controllability through pitches for etching CD correction. Simulation results also show that the pitch with a middle CD sensitivity makes the CD correction sensitivity difference minimum through pitches. From the simulation, the sensitivity behaviors are found to be relatively similar for both of PEB temperature and dose control. Rather than sensitivity behavior differences between the two CD control methods, the intra-wafer spatial resolution of the CD control methods is found to be an important factor for the strategy of CD optimization. Finally, by contact-layer CD optimization, across-wafer CDUs are improved by more than 50%. The variation in the electric resistance of contacts is also improved by more than 20%. As a result, the proposed method is found to be effective for CDU improvement of through-pitch contact-hole patterning for advanced logic device.
Here we present both simulation and experimental results that show the effect of changes in laser light source bandwidth (E95) on CD Iso-Dense Bias. For the 55nm Technology Node Device, we have shown that E95 stability of less than 0.11pm is required in order to maintain OPE variation to within 2nm. In addition, we also verified another method to adjust for OPE variations that occur when E95 fluctuates. The Contrast Adjustment method is an effective function to adjust for OPE variation due to E95 fluctuation; it has been shown to maintain OPE variation less than 1.5nm. Furthermore, for the 45nm Technology Node Device, we have demonstrated that E95 stability of less than 0.07pm is required to maintain OPE variation to within 1nm. The bandwidth performance of the latest laser light source exhibits E95 stability less than 0.03 pm, thereby showing that the OPE variation due to E95 can be kept to under 1nm.
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