Application of scatterometry for CD and profile metrology in 193-nm lithography process development

Chen, Li-Jui; Ke, Chih-Ming; Yu, Shinn-Sheng; Gau, Tsai‐Sheng; Chen, Pei-Hung; Ku, Y.H.; Lin, Burn J.; Engelhard, Dan; Hetzer, Dave; Yang, Jason; Barry, Kelly A.; Yap, Lip; Yang, Wenge

doi:10.1117/12.483692

Cited by 4 publications

(4 citation statements)

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“…Due to the small size of the hardware, the method is the preferred choice for inline metrology applications. Also from a CD metrology perspective, scatterometry is interesting: CD's can be measured with a good repeatability [7], along with additional shape information [8]. Since CD-scatterometry uses quite a large spot to determine the average CD of a grating the expectation was that TTR numbers would be very low too.…”

Section: Results With CD Scatterometrymentioning

confidence: 99%

Total test repeatability: a new figure of merit for CD metrology tools

Cramer

Kiers

Vanoppen

et al. 2004

Metrology, Inspection, and Process Control for Microlithography XVIII

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Evaluations of CD-metrology tools usually focus on resolution, repeatability and accuracy. These are traditional metrics which relate to the capability to measure a local line width. These metrics do not cover the capability to map the CD fingerprint (uniformity map) of the wafer and scanner field, which are essential for sub-100nm lithography process control. In this study, CD-uniformity wafers of state-of-the-art step-and-scan systems were measured with different metrology tools. Analysis of the results revealed a random contribution that could not be attributed to the exposure tool or to the repeatability of the metrology tool. A test and analysis method was developed to separate out this random contribution from the test results. The level of this random CD variation, called the Total Test Repeatability (TTR), is proposed here as a new metric to compare CD-metrology tools in their capability to generate CD uniformity maps. The method was applied to study CD-SEM, Electrical Line width Measurements and CD-scatterometry. In general, the TTR appears to be much larger than the metrology tool repeatability. As such it is an important figure of merit for CD metrology tools used to reveal fingerprints of reticles, exposure tools or processing tools. The TTR is dependent on the metrology tool, measurement algorithm, but also on materials and processing flow and conditions. Some root causes have been identified, such as the wafer resistivity properties for ELM or line width roughness that appears as CD variation in CD-SEM tools. Modifications can be made in the metrology strategy to suppress the TTR and reveal more reliable CDuniformity fingerprints.

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Section: Results With CD Scatterometrymentioning

confidence: 99%

Total test repeatability: a new figure of merit for CD metrology tools

Cramer

Kiers

Vanoppen

et al. 2004

Metrology, Inspection, and Process Control for Microlithography XVIII

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“…The library is setup using a gate pattern, in which DICD is split in the range of 80~110 nm, and is correlated between measured CD and values measured through CD-SEM. In order to verify measurability of patterns through OCD, other information was minimized through the formation of a simple gate pattern without a sub layer [3,4]. It was shown in figure 1 that the DICD results using CD-SEM depending on dose changes formed by 98 nm targets.…”

Section: Verification Of Optical Scatterometrymentioning

confidence: 99%

“…As an alternate method of CD measurement, optical scatterometry (OCD), which does not possess the problem of shrinkage, is being introduced [1,2]. For its introduction, by an OCD setup in the work process of sub-80nm node, a comparison and assessment was made with the existing metrology method that is currently being applied.…”

Section: Introductionmentioning

confidence: 99%

Application of scatterometry to measure organic material profile

Koo¹,

Ban²,

Lim³

et al. 2006

SPIE Proceedings

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Scanning Electron Microscope (SEM) has been typical methods for measuring CD of nanopatterns until ArF process was introduced. However in case of ArF process, this method has serious drawback such as shrinkage of organic material by the irradiation of high-energy electron beam. The optical scatterometry system is considered to be promising method for measuring CD due to no damage on organic materials. Sub-80nm node gate was selected because of its measurement stability. CD, profile and thickness are compared with those measured by CD-SEM, cress-section SEM. The correlation degree is shown as GOF, R2, and Profile. Based on merit of speed, easiness and accurate measurement, optical CD method has been applied to CD uniformity. CD uniformity measured by OCD was very similar to that measured by SEM on gate pattern. Based on this result, OCD was applied for the improvement of CD uniformity combined with ASML's does-mapper in technology. We investigated the variation of thickness of organic BARC over topology of various size line and space patterned poly-Si by OCD.

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“…A large number of papers have reported data comparing SCD to SEM [3][4][5][6]. Because of the low throughput of SEM, it was not easy to obtain large sampling on the wafer for comparison purpose.…”

Section: Introductionmentioning

confidence: 99%

Methods for evaluating lithographic performance of exposure tools for the 45-nm node: ECD and scatterometry

Huang

Rice

Coombs

et al. 2004

Metrology, Inspection, and Process Control for Microlithography XVIII

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This paper compares two metrology methodologies, ECD (Electrical CD) and SCD (Spectroscopic CD), for the 45nm-node-like gate level. Measurements were taken on both metrology tools, for different features, and the data was processed to reflect the exposure tool's fingerprint within the exposure field. ACLV (cross chip line-width variation) and through-focus measurements were also collected. There is a DC bias between the ECD and SCD. The cross slit and cross scan average plots are very similar between the two methods. The correlation between ECD and SCD gave R² of 0.95 and 0.92 for 220nm and 480nm pitches respectively. Results showed that SCD is a viable candidate to replace ECD for characterizing the exposure system for the 45nm node. Data also showed that there are fundamental differences between the two methods that cannot be attributed to random errors. These differences account for less than 1nm at 3 σ.

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Application of scatterometry for CD and profile metrology in 193-nm lithography process development

Cited by 4 publications

References 0 publications

Total test repeatability: a new figure of merit for CD metrology tools

Total test repeatability: a new figure of merit for CD metrology tools

Application of scatterometry to measure organic material profile

Methods for evaluating lithographic performance of exposure tools for the 45-nm node: ECD and scatterometry

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