This paper presents the properties of the Sigma7300 which is a commercial DUV laser pattern generator based on spatial light modulator (SLM) technology designed to meet the requirements of the 65-nm technology node and below. The introduction of spatial light modulators provides a possibility for optical mask writers to combine high resolution and accuracy with short write time making it possible to write most of the high end mask layers in a cost effective way. The Sigma7300 mask writer is developed by Micronic Laser Systems whereas the SLM, which is a combined MEMS and CMOS component with individually controllable movable micromirrors, is developed by the Fraunhofer-IPMS institute in Dresden. The SLM allows parallel writing of one million pixels with a frame rate of up to 2 kHz. The technology offers resolution enhancement advantages from stepper technology not available in other mask patterning tools.
The Fraunhofer IPMS and Micronic Laser Systems AB have developed a technology for microlithography using spatial light modulation (SLM). This technology uses an array of micromirrors as a programmable mask, which allows parallel writing of 1 million pixels with a frame rate of up to 2 kHz. The SLM is fabricated at the IPMS using its high-voltage CMOS process. The mirrors are fabricated by surface micromachining using a polymer as sacrificial layer. The mirrors are operated in an analog mode to allow sub-pixel placement of pattern features. This paper describes the function of the SLM with an emphasis on the stability of the mirror deflection and a method to improve it which has been implemented.
An architecture for SLM-based mask writing and optical maskless lithography has been described in previous articles. This work reports on phase-shifting capabilities of different SLM's in light of rasterization and image stability. The tilting mirror SLM proven in the Micronic Sigma7300 mask writer has in other papers been presented as comparable to an attenuated phase-shift reticle. This article will feature the novel tilting phase-step mirror SLM. which has phase shifting capabilities enabling it to emulate hard phase-shift reticles.
For a straight-forward rasterization architecture where individual pixels are determined by local pattern data it is required that the complex amplitude created by a mirror is confined to the real axis. This is the case for both the normal tilting mirror and the tilting phase-step mirror. For other micro-mirror designs this might not be true and in the case of the piston-mirror SLM this requirement leads to the demand that two or several mirrors work collectively, loosing degrees of freedom and resolution.
The tilting phase-step mirror SLM provides a new rule-set for lithography: no penalty for phase shifting or aggressive OPC, seamless pattern decompositions, choice of optimal tones for each pattern, etc. This gives performance and flexibility not possible before.
Sigma7100 is a revolutionary new architecture for Laser Pattern Generators being developed by Micronic Laser Systems. The Sigma7100 system design uses a unique architecture based on a spatial light modulator (SLM), a MEMS consisting of a 1 million pixel micro-mirror array fabricated onto a CMOS substrate. The SLM functions as a dynamic mask which is illuminated by a 1kHz DUV excimer laser. A new pattern is calculated and downloaded into the SLM for each laser pulse, and the resultant SLM image is then projected on to the mask substrate. This paper describes the Sigma7100 architecture, presents recent results, and presents a look into the path toward extending the SLM technology to the 70nm node and beyond.
A new breed of pattern generators for photomasks using a new DUV spatial light modulator (SLM) technology is under development in a collaborative effort between Micronic Laser Systems AB, Taby, Sweden and the Fraunhofer Institute for Microelectronic Circuits and Systems (FhG-IMS), Dresden, Germany. Current pattern generator architectures using a limited number of scanning beams will not be able to support future production requirements with ever-increasing data complexity and resolution. The new SLM technology provides a means for high resolution and massive parallel exposure to alleviate these difficulties. There are many architectural similarities to that of a modern stepper and the technology can provide the resolution to rival that of e-beam pattern generators, yet with the productivity of laser patterning. In this paper we describe the architecture of an SLM exposure system, the SLM technology, and will consider key aspects for the intended application.