65-55nmLogic-Devices require high performance of not only the resolution, of but also the overlay accuracy (Mean+3sigmas < 20-30nm). Thus, here, overlay performance of several layers in our advanced devices is investigated with using Immersion-exposure-tool. We used the new alignment system called SMASH TM which has the phase grating alignment sensor newly installed in our immersion-exposure-tool (XT1400Ei). SMASH supports flexible mark design in terms of size and pitch of the grating so that it can comply for our design requirement. SMASH has much smaller alignment beam size of ~ 40um for it.New mark design for our 65-55nm process will be investigated so as to obtain higher alignment accuracy than that of current marks. The alignment performance becomes more accurate proportionally to data density of the mark and it depends on the diffraction angle and efficiency from the mark. Thus, to obtain acceptable alignment accuracy with smaller mark, it should be designed such as diffraction efficiency is maximized within the required boundary condition in the pitch [diffraction angle] and segmentation of the mark.In this paper, several new marks are designed and evaluated. The evaluation shows that comparable performance could be obtained in the new design mark as in ASML's conventional marks. Finally, we select one from the new smaller marks and apply it to our 65-55nm process, especially, to the five process modules , and performance within 20nm (Mean+3sigmas) are typically obtained. The overlay accuracy needed for our 65-55nm Logic-Devices is successfully achieved with immersion-exposure-tool. SMASH* (SMart Alignment Sensor Hybrid) : the name of alignment system using with phase grating alignment sensor.

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Electron beam (EB) lithography has often been used for fabricating advanced ULSIs. Recently, to increase the throughput, EB projection lithography (EPL) has been proposed. If 100 kV acceleration voltage and 20 to 30 iA beam current are to be adopted in this technology, a high sensitivity resist will have to be developed to achieve a throughput of more than 30 wafers/hour (8"4). In this paper, we show the photoacid generator (PAG) optimization of a polyhydroxysterene (PHS) -based chemically amplified negative resist for EPL. To evaluate the resist sensitivity and the resolution, we prepared the PHSbased negative resists with PAGs of various quantum yields of acid generation, which were the onium-salt-type PAG, the imide-type PAG, and the alkylbenzene-type PAG. The cross-linker was the melamine-type one. To simultaneously obtain a high sensitivity of less than 10.0 C/cm2 and a high resolution of less than 0.10 tm, a PHS-based negative resist with the imide-type PAG was most preferable. With this resist, we successfully obtained 0.08-gm gate line patterns (128K sub-array of DRAM), exposed by one 250x250 im2 EB shot using a 100-ky EB projection experimental column. In addition, the throughput was estimated to be 30 wafers/hour (8'4) or more.

Electron beam (EB) lithography has long been used for fabricating advanced ULSIs. Recently, to increase the writing throughput, electron beam projection lithography (EPL) technology has been proposed (100kV acceleration voltage and 20-30µA total currents). When we implement this technology to mass production, the data conversion system and EPL mask, which is different from conventional optical mask, have to be developed.In EPL mask conversion system, it is necessary to divide a full chip data into 1mmb1mm (250um b 250um on the wafer) sub-fields, which size is as same as the EPL shot size with format conversion.In this paper, we show the data conversion system that converts pattern data (GDS ) to EPL mask data.This system can maintain the hierarchy data structure in the dividing process to sub-fields. The patterns that located on the boundary between neighboring sub-fields will be treated as belonging in either field for the prevention of critical division. We have developed a data conversion system for EPL mask that can divide the device data with high speed and high quality.