Controlling the Local CD Uniformity is important for the implementation of EUV lithography in high-volume production. Spatial frequency breakdown of stochastic effects and identification of stochastic noise contributors may help us to understand the current performance and suggest possibilities and pathways for future improvement. In this work, we look for potentially hidden sources of systematic local variability by collecting and analyzing CD metrology data over lengths greater than a single SEM field of view (FOV). Fourier analysis of the CD data is used to identify any systematic variability. This work will enable a more accurate breakdown of local variability. Additionally, using the length scale of any observed systematic signal we can attempt to trace back the origin and reduce or eliminate its source.

Extreme ultraviolet (EUV) lithography is expected to succeed in 193-nm immersion multi-patterning technology for -sub-10-nm critical layer patterning. In order to be successful, EUV lithography has to demonstrate that it can satisfy the industry requirements in the following critical areas: power, dose stability, etendue, spectral content, and lifetime. Currently, development of second-generation laser-produced plasma (LPP) light sources for the ASML's NXE: 3300B EUV scanner is complete, and first units are installed and operational at chipmaker customers. We describe different aspects and performance characteristics of the sources, dose -stability results, power scaling, and availability data for EUV sources and also report new development results.

This paper describes the development and evolution of the critical architecture for a laser-produced-plasma (LPP) extreme-ultraviolet (EUV) source for advanced lithography applications in high volume manufacturing (HVM). In this paper we discuss the most recent results from high power sources in the field and testing on our laboratory based development systems, and describe the requirements and technical challenges related to successful implementation of those technologies on production sources. System performance is shown, focusing on pre-pulse operation with high conversion efficiency (CE) and with dose control to ensure high die yield. Finally, experimental results evaluating technologies for generating stable EUV power output for a high volume manufacturing (HVM) LPP source will be reviewed.

Laser produced plasma (LPP) light sources have been developed as the primary approach for EUV scanner imaging of circuit features in sub-20nm devices in high volume manufacturing (HVM). This paper provides a review of development progress and readiness status for the LPP extreme-ultra-violet (EUV) source. We present the latest performance results from second generation sources, including Prepulse operation for high power, collector protection for long lifetime and low cost of ownership, and dose stability for high yield. Increased EUV power is provided by a more powerful drive laser and the use of Prepulse operation for higher conversion efficiciency. Advanced automation and controls have been developed to provide the power and energy stability performance required during production fab operation. We will also discuss lifetesting of the collector in Prepulse mode and show the ability of the debris mitigation systems to keep the collector multi-layer coating free from damage and maintain high reflectivity.

This paper describes the development of a laser-produced-plasma (LPP) extreme-ultraviolet (EUV) source for advanced lithography applications in high volume manufacturing. EUV lithography is expected to succeed 193nm immersion double patterning technology for sub-20nm critical layer patterning. In this paper we discuss the most recent results from high power testing on our development systems targeted at the 250W configuration, and describe the requirements and technical challenges related to successful implementation of these technologies. Subsystem performance will be shown including Conversion Efficiency (CE), dose control, collector protection and out-of-band (OOB) radiation measurements. This presentation reviews the experimental results obtained on systems with a focus on the topics most critical for a 250W HVM LPP source.

Laser produced plasma (LPP) systems are the leading approach for extreme-ultra-violet (EUV) lithography of circuit features at sub-20nm nodes. This paper reviews technology and development progress for high-power sources optimized for EUV lithography. Article not available.

The paper develops achieved performance bounds for MPC control applied over the infinite horizon to constrained systems with persistent disturbances and persistently active constraints. This is approached from a minimalist perspective of introducing as few assumptions as possible and separating the feasibility analysis, which is shown to be purely topological, from the performance analysis, which is based on value functions and builds on the work of Jadbabaie, Hauser, Grüne and Rantzer. A specific focus is on the requirements for stability, where MPC stability in the sense of bounded-input/bounded-state is addressed.

At high-utilization lithography sites, laser light source gas replenishments and gas maintenance operations typically require between 9 and 16 hours per year, during which the light source is unavailable for production. Reducing this downtime is important for increasing the productivity of the lithography cell. Light sources also require intermittent gas maintenance that must be performed manually and therefore can be subject to variability in duration and repeatability. This paper will outline the targeted improvements in availability achieved by equipping the light source with Cymer's iGLXTM Gas Management System. The iGLX System extends the pulse-based interval between gas refills to 4 billion pulses for Cymer's XLA-series and XLR-series light sources, while maintaining existing performance. Additionally, the iGLX System automates some gas maintenance events that were previously manual, improving their speed and reducing variability. This paper will provide some performance data during extended light source operation on lithography cells equipped with the iGLX System. For high-utilization lithography cells, the iGLX System can reduce gas maintenance related downtime by up to 75%, increasing light source availability up to 12 hours per year. Total halogen gas usage can also be reduced by up to 16%, and manual gas maintenance events can be eliminated. The iGLX System has been installed on multiple high-volume scanner systems, which experienced these improvements immediately, and are continuing to operate nominally. As the iGLX System is deployed in volume, additional availability improvements can be realized by more readily synchronizing other lithography line maintenance events with gas replenishment events.

We study a disturbance rejection problem in a pulsed light source with the aim of yielding improved performance over existing control techniques. The disturbances of interest include an offset with reset properties and sinusoids which appear aliased in the measured data. The light source is pulsed at varying pulse rates yet actuators move in continuous-time, yielding a system which blends aspects of continuous-time and variable data rate discrete-time. We employ continuous-discrete Kalman filtering ideas for state estimation and establish and solve a regularized minimum variance control problem under a disturbance rejection framework. We show that the proposed controller has the capacity to remove aliased sinusoids from the measured output and yields improved performance over existing light source algorithms.

The continuous evolution of the semiconductor market necessitates ever-increasing improvements in DUV light source uptime as defined in the SEMI E10 standard. Cymer is developing technologies to exceed current and projected light source availability requirements via significant reduction in light source downtime. As an example, consider discharge chamber gas management functions which comprise a sizable portion of DUV light source downtime. Cymer's recent introduction of Gas Lifetime Extension (GLXTM) as a productivity improvement technology for its DUV lithography light sources has demonstrated noteworthy reduction in downtime. This has been achieved by reducing the frequency of full gas replenishment events from once per 100 million pulses to as low as once per 2 billion pulses. Cymer has continued to develop relevant technologies that target further reduction in downtime associated with light source gas management functions. Cymer's current subject is the development of technologies to reduce downtime associated with gas state optimization (e.g. total chamber gas pressure) and gas life duration. Current gas state optimization involves execution of a manual procedure at regular intervals throughout the lifetime of light source core components. Cymer aims to introduce a product enhancement - iGLXTM - that eliminates the need for the manual procedure and, further, achieves 4 billion pulse gas lives. Projections of uptime on DUV light sources indicate that downtime associated with gas management will be reduced by 70% when compared with GLX2. In addition to reducing downtime, iGLX reduces DUV light source cost of operation by constraining gas usage. Usage of fluorine rich Halogen gas mix has been reduced by 20% over GLX2.

We derive and establish properties for an algorithm for the distributed optimization of a global constrained optimization problem through the limited communication of data between cooperating subsystems; each subsystem solves a local optimization problem. The structure of the optimization problem is such that it is performed by the distinct subsystems, which have their own objective functions and local constraints, but share a common coupled constraint which limits the behavior of the independent systems. Our interest is in performing a distributed computation of the global solution without the participating subsystems needing explicit knowledge of other members' dynamics, constraints, cost functions, or state. We propose a set of distributed algorithms which solve the global problem given limited communication and identify cases in which the subsystems must communicate more information than is desired.

The ability to extend deep ultraviolet (DUV) lithography into the 32 and sub-32nm domain has more recently relied on improvements in source-mask optimization (SMO), double patterning (DP) and complex, pixellated illumination patterns. Yet these techniques require a commensurate improvement in the light source that powers the latest generation scanners in order to enable high performance at high throughput. This paper will show detailed performance results of the latest-generation light source from Cymer that incorporates flexible power with dramatic improvements in dose, wavelength and bandwidth stability.

Increasing productivity demands on leading-edge scanners require greatly improved light source availability. This translates directly to minimizing downtime and maximizing productive time, as defined in the SEMI E10 standard. Focused efforts to achieve these goals are ongoing and Cymer has demonstrated significant improvements on production light sources. This paper describes significant availability improvements of Cymer light sources enabled by a new advanced gas management scheme called Gas Lifetime eXtensioTM (GLTM) control system. Using GLX, we have demonstrated the capability of extending the pulse-based interval between full gas replenishments to 1 billion pulses on our XLA light sources, as well as significant extension in the time-based interval between refills. This represents a factor of 10X increase in the maximum interval between full gas replenishments, which equates to potential gain of up to 2% in productive time over a year for systems operating at high utilization. In this paper, we provide performance data on extended (1 billion pulse) laser operation without full gas replenishment under multiple actual practical production environments demonstrating the ability to achieve long gas lives with very stable optical performance from the laser system. In particular, we have demonstrated that GLX can provide excellent stability in key optical performance parameters, such as bandwidth, over extended gas lives. Further, these stability benefits can be realized under both high and low pulse accumulation scenarios. In addition, we briefly discuss the potential for future gas management enhancements that will provide even longer term system performance stability and corresponding reductions in tool downtime.