Evaluation of line and hole measurement by high-resolution low-magnification CD SEM

Ke, Chih-Ming; Lee, Chi-Chuang; Wang, Yu-Hsi; Lee, Heng-Jen; Lin, Chin-Hsiang; Gau, Tsai‐Sheng; Lin, Burn J.; Kawada, Hiroki; Ueda, Kazuhiro; Nomura, Hiroaki; Ren, Nelson; Iizumi, Takashi

doi:10.1117/12.601133

Cited by 3 publications

(7 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…8. This difference is caused by line-edge roughness [3], because OCD is a LER insensitive metrology. Later we will discuss how to improve the metrology quality through different scan methodologies without losing CD sensitivity by using these pitch offsets samples.…”

Section: Data Quality Indexmentioning

confidence: 98%

See 1 more Smart Citation

Sub-nanometer pitch calibration and data quality evaluation methodology

Wang

Huang

et al. 2008

SPIE Proceedings

Self Cite

View full text Add to dashboard Cite

Average CD of CD SEM and scatterometry CD (OCD) have been adopted for advanced CD control. The advantages and disadvantages of these two CD metrologies have been well discussed [3,5]. The target of CD uniformity (CDU) for advanced technology has been driven to 1 nm, i.e. about three and half the size of a silicon atom, which is 0.29 nm. In the real production environment, engineers need to face sub-nanometer (< 1 nm) CD variations and do the necessary process corrections to meet the 1-nm CDU requirement. In other words, advanced CD process control has already been in the world of atomic scale. It turns out that methodology to ensure the accuracy of sub-nanometer CD has become essential for advanced CD control.In this paper, we introduced a methodology to produce 0.25, 0.5, and 1 nm programmed pitch offsets through mask design. These offsets are attainable with current process capability. Pitch offsets instead of line/space width offsets were used because the pitch is relatively process insensitive. The pitch has already been widely used as a CD SEM magnification calibration standard, e.g. Hitachi m-scale 240-nm pitch and VLSI 100-nm pitch standards. We produced large and small pitch splits to meet different magnification linearity requirements. We also used optical CD to verify the programmed pitch offset. Using the raw spectrum of OCD, systematic pitch signal changes in 0.25-nm steps can be detected, ensuring that 0.25-nm pitch offset standards are meaningful. Interestingly, 0.25 nm is smaller than the 0.29-nm Si atom.We also used this standard wafer to do the sampling size or data quality evaluation for different CD SEM measurement methodologies, e.g. 150K by 150K or 80K by 35K magnifications that in turn dictates the sample size. Pitch sensitivity is strongly related to the sampling size and line-edge roughness (LER). For example, 0.25-nm pitch sensitivity needs a larger sampling size than those of 0.5-nm and 1-nm pitch sensitivities.By means of this standard wafer, we can easily quantify metrology quality as well as choose the right metrology and sampling size for advanced process control.

show abstract

Section: Data Quality Indexmentioning

confidence: 98%

“…The advantages and disadvantages of these two CD metrologies have been well discussed [3,5]. The target of CD uniformity (CDU) for advanced technology has been driven to 1 nm, i.e.…”

mentioning

confidence: 99%

Sub-nanometer pitch calibration and data quality evaluation methodology

Wang

Huang

et al. 2008

SPIE Proceedings

Self Cite

View full text Add to dashboard Cite

show abstract

“…Each in the RHS of (21) is repeatedly calculated, ex: and are identical and counted. Therefore, (21) can be revised as (22) which is also identical to (8) with…”

Section: Appendixmentioning

confidence: 99%

“…(20) Given in (8), we have which is identical to (20). Each can be further expressed in terms of the sample variances of the samples with observations, and (20) becomes (21) where denotes the sample variance based on observations wherein the th and th observations are both excluded. Each in the RHS of (21) is repeatedly calculated, ex: and are identical and counted.…”

Section: Appendixmentioning

confidence: 99%

“…Although the measurement precision of OCD is better than SEM for the 65 nm technology node, the recipe and library generation of OCD is more complicated and time consuming. Ke et al [21] proposed a concept on OCDlike CD SEM measurement which is said to be the average line width (ALW) or contact hole diameter (ACD) measurement at high resolution and low magnification CD SEM. These measurements, i.e., SEM CD, ALW/ACD, and OCD, manifest different significances of systematic variations of the same wafer due to the measuring precision.…”

Section: B Wafer Metrology Data With Different Precision Levelsmentioning

confidence: 99%

See 1 more Smart Citation

Spatial Variance Spectrum Analysis and Its Application to Unsupervised Detection of Systematic Wafer Spatial Variations

Blue

Chen

2011

IEEE Trans. Automat. Sci. Eng.

View full text Add to dashboard Cite

Investigation of wafer spatial variations is critical for semiconductor process/equipment optimization and circuit design. The objective of spatial variation study is to differentiate the systematic variation component from the random component. This is usually done by contrasting with a set of known systematic patterns based on engineering knowledge. However, there could exist unknown systematic components remaining in the unexplained residuals and overlooked by the conventional spatial variation study. In this paper, we develop a novel spatial variance spectrum ( ) to analyze the systematic variations without any priori information of the systematic patterns. The is a series of spatial variations over a range of spatial moving window sizes from the smallest spatial moving window consisting of only two metrology sites to the largest one covering all metrology sites of the entire wafer. The can be used to characterize the wafer spatial variations and to detect existence of systematic variations by a proposed hypothesis test. We also propose an index to summarize from the the systematic proportion of the spatial variation. The proposed test and index of systematic variations will be demonstrated and validated through both hypothetical examples and actual cases of wafer critical dimension (CD) metrology data.Note to Practitioners-Wafer spatial variations study is critical to within-wafer control and optimization. Only through investigation of the spatial variations on the wafer surface do we get to learn more about the nature of the semiconductor process/equipment and the manufacturability of certain circuit design patterns. In this paper, we propose a novel analysis tool to help engineers characterize the wafer spatial variations and distinguish the systematic variation from the random variation. With the spatial systematic variations identified and described, the engineers can discover the opportunities to further improve the processing quality and thus the final yield.

show abstract

The study of high-sensitive and accurate metrology method by using CD-SEM

2012

View full text Add to dashboard Cite

The earliest semiconductor device manufacturing employed optical microscopes for measurement and control of manufacturing process. The introduction of Critical Dimension Scanning Electron Microscope (CD-SEM) in 1984 provided a tremendous increase in capability for process monitoring and has been the standard for in-line metrology for over 25 years. The advantages of CD-SEM are highly accurate and stable measurement reproducibility at very specific locations throughout the device. The evolution of CD-SEM in Metrology has included improved resolution, development of advanced measurement and pattern recognition algorithms, all required by performance improvement demands from the market.Current conventional metrology using in-line CD-SEM involves measuring about ten points per wafer (one or more points per one chip). At a magnification of over x150k (Field of View is about 1μm 2 ). In contrast, the area of measurement pattern on chip is much larger than the area of CD-SEM measurement (mm 2 : (on chip) versus μm 2 : (CD-SEM measurement)). This would mean that the result of CD-SEM measurement is influenced by local pattern variation.The very stringent requirements placed on in-line Metrology for the last couple of technology nodes has produced an additional metrology methodology, beyond the CD-SEM, that involves large area measurements with very high precision for the most critical levels. We will refer to this methodology as "Macro Area Measurements". We reported the applicability of using a CD-SEM Macro Area Measurements methodology in SPIE2011 (797124). In the results, we were able to validate a new methodology that we called "Macro Area Measurement" which is demonstrated to successfully detect small process variations with the same throughput and reduced damage to the pattern.This time, we investigated the additional applicability of using a CD-SEM Macro Area Measurement methodology in this paper.The areas investigated focused on the following points: 1) Measurement repeatability related to CD-SEM measurement 2) Optimization of the measurement parameters using new function 3) Verification of Macro Area Measurement with a leading -edge deviceIn the results, we are able to validate "Macro Area Measurements methodology which is demonstrated to successfully detect further small process variations with the almost same throughput and reduced damage to pattern.

show abstract

Evaluation of line and hole measurement by high-resolution low-magnification CD SEM

Cited by 3 publications

References 3 publications

Sub-nanometer pitch calibration and data quality evaluation methodology

Sub-nanometer pitch calibration and data quality evaluation methodology

Spatial Variance Spectrum Analysis and Its Application to Unsupervised Detection of Systematic Wafer Spatial Variations

The study of high-sensitive and accurate metrology method by using CD-SEM

Contact Info

Product

Resources

About