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The system concepts used in a novel approach for a high throughput maskless lithography system called reflective electron beam lithography (REBL) are described. The system is specifically targeting five to seven wafer levels per hour throughput on average at the 45nm node, with extendibility to the 32nm node and beyond. REBL incorporates a number of novel technologies to generate and expose lithographic patterns at estimated throughputs considerably higher than electron beam lithography has been able to achieve as yet. A patented reflective electron optic concept enables the unique approach utilized for the digital pattern generator (DPG). The DPG is a complementary metal oxide semiconductor application specific integrated circuit chip with an array of small, independently controllable metallic cells or pixels, which act as an array of electron mirrors. In this way, the system is capable of generating the pattern to be written using massively parallel exposure by ∼1×106 beams at extremely high data rates (∼1Tbit∕s compressed data). A rotary stage concept using a rotating platen carrying multiple wafers optimizes the writing strategy of the DPG.

Multiaxis and multibeam technology for high throughput maskless E-beam lithography J. Vac. Sci. Technol. B 30, 06FC01 (2012); 10.1116/1.4767275 High-current electron optical design for reflective electron beam lithography direct write lithography J. Vac. Sci. Technol. B 28, C6C1 (2010); 10.1116/1.3505130 REBL: A novel approach to high speed maskless electron beam direct write lithographyReflective electron beam litography ͑REBL͒ utilizes several novel technologies to generate and expose lithographic patterns at throughputs that could make ebeam maskless lithography feasible for high volume manufacturing. The REBL program was described in a previous article ͓P. Petric et al., J. Vac. Sci. Technol. B 27, 161 ͑2009͔͒ 2 years ago. This article will review the system architecture and the progress of REBL in the past 2 years. The main technologies making REBL unique are the reflective electron optics, the rotary stage, and the dynamic pattern generator ͑DPG͒. Changes in how these concepts have been implemented in a new design will be discussed. The main disadvantage of today's electron beam direct write is low throughput; it takes many tens of hours to expose a 300 mm wafer today using ebeam lithography. The projected system throughput performance with the integrated technology of the reflective optics, DPG, and a multiple wafer rotary stage will be shown incorporating the performance data for the new column design. C6C10 Petric et al.: Reflective electron beam lithography: A maskless ebeam direct write lithography C6C10 J.

REBL (Reflective Electron Beam Lithography) is being developed for high throughput electron beam direct write maskless lithography. The system is specifically targeting 5 to 7 wafer levels per hour throughput on average at the 45 nm node, with extendibility to the 32 nm node and beyond. REBL incorporates a number of novel technologies to generate and expose lithographic patterns at estimated throughputs considerably higher than electron beam lithography has been able to achieve as yet. A patented reflective electron optic concept enables the unique approach utilized for the Digital Pattern Generator (DPG). The DPG is a CMOS ASIC chip with an array of small, independently controllable cells or pixels, which act as an array of electron mirrors. In this way, the system is capable of generating the pattern to be written using massively parallel exposure by ~1 million beams at extremely high data rates (~ 1Tbps). A rotary stage concept using a rotating platen carrying multiple wafers optimizes the writing strategy of the DPG to achieve the capability of high throughput for sparse pattern wafer levels. The exposure method utilized by the DPG was emulated on a Vistec VB-6 in order to validate the gray level exposure method used in REBL. Results of these exposure tests are discussed.

Micronic is developing a massively parallel pattern generation system based on a micro-mechanical spatial light modulator (SLM). The electro-mechanical and optical properties of the micromirrors in the SLM can vary from one to another and over time. Therefore the response of each mirror must be calibrated, with accuracy sufficient to maintain CD uniformity requirements. We present a practical method for performing this calibration which greatly improves the micromirror grayscale uniformity and reduces CD error contribution from the SLM to less than 2nm.

REBL (Reflective Electron Beam Lithography) is a program for the development of a novel approach for highthroughput maskless lithography. The program at KLA-Tencor is funded under the DARPA Maskless Nanowriter Program. A DPG (digital pattern generator) chip containing over 1 million reflective pixels that can be individually turned on or off is used to project an electron beam pattern onto the wafer. The DARPA program is targeting 5 to 7 wafers per hour at the 45 nm node, and this paper will describe improvements to both increase the throughput as well as extend the system to the 2x nm node and beyond.This paper focuses on three specific areas of REBL technology. First, a new column design has been developed based on a Wien filter to separate the illumination and projection beams. The new column design is much smaller, and has better performance both in resolution and throughput than the first column which used a magnetic prism for separation. This new column design is the first step leading to a multiple column system. Second, the rotary stage latest results of a fully integrated DPG CMOS chip with lenslets will be reviewed. An array of over 1 million micro lenses which is fabricated on top of the CMOS DPG chip has been developed. The microlens array eliminates crosstalk between adjacent pixels, maximizes contrast between on and off states, and provides matching of the NA between the DPG reflector and the projection optics.

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