A Study of Dry Etching Process for Sigma-Shaped Si Recess

Sui, Yun-Qi; Han, Qiu-Hua; Qing-song, Wei; Chang, Shih-Mou; Lee, Kwok-Fung

doi:10.1149/1.3694336

Cited by 4 publications

(5 citation statements)

References 2 publications

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“…So it is important to optimize the Σ-Si 1-x Ge x to add sufficient amount of stress/strain to the channel region. The post wet etch Σ-shaped trench profile is strongly correlated to the final embedded Σ-Si 1-x Ge x , which requires strict control (8). The total depth height (DH), tip depth (TD) and tip off gate (ToG) of the Σ-shaped trench profile are considered as the key parameters for the profile characterization (Fig.…”

Section: The Tunable Capability Of σ-Shaped Trench Profile For Planar...mentioning

confidence: 99%

Strained p-Channel MOSFET Fabrication Challenge and Perspective for the 28-Nm Technology Node and Beyond

2015

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The embedded epitaxial silicon germanium (eSi1-xGex) in the recessed source/drain (S/D) area modulates the lattice constant and band structure of silicon at the channel region then enhances the hole/electron mobility of MOSFETs. For the 28nm node planar devices, the strict control of recessed profile could be achieved by plasma-based one-step or two-step silicon dry etch process combined with the post wet chemical treatments. Here we analyzed the process loading correlated to the pitch of gate electrodes and the tunable capability on final sigma-shaped trench profile for these two types of processes. The strain/stress induced mobility enhancement technique of fin structure FETs should be significantly different from that of traditional planar FETs. We successfully decoupled the trade-off between the gate capping layer protection and the silicon nitride spacer pull-back before the p-channel fin recess step. Additionally, by balancing the isotropic and anisotropic spacer open parts in the whole etch process, we also demonstrated the fin structures with flat and smooth recessed surface on their top area, which would benefit for future good crystalline and well controlled Pi-shaped eSi1-xGex growth.

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Section: The Tunable Capability Of σ-Shaped Trench Profile For Planar...mentioning

confidence: 99%

Strained p-Channel MOSFET Fabrication Challenge and Perspective for the 28-Nm Technology Node and Beyond

2015

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“…The sigma shaped silicon recess is formed after the post-etch treatment process. Normally, the tip depth of the final sigma shape strongly depends on that of a bowing shaped recess [5] . PSR dry etch process mostly determines the critical geometry profile of a sigma shape.…”

Section: Doe Wafer Preparation and Modeling Requirementmentioning

confidence: 99%

“…(b) Effect of Anisotropic Etch on Bowing Shaped Silicon Recess. [5] Figure 3 shows the modeling requirements for OCD. There're 18 output parameters (1~8 and a~i) that are needed for the sigma shape PSR OCD library building.…”

Section: Doe Wafer Preparation and Modeling Requirementmentioning

confidence: 99%

2-D Modeling Capability Certification of Optical Critical Dimension (OCD) Metrology Tool by Sigma Shape PMOS Silicon Recess Structure

2014

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Optical Critical Dimension (OCD) metrology is a much popular and efficient way to monitor structure sizes such as heights, side wall angles (SWAs), and critical dimensions (CDs). Due to the continuous shrinkage of feature sizes, the IC process is becoming more and more complicated. The growing demand on the OCD applications always outpaces the development of OCD-technology capabilities. Thus, we have to find a more reliable method and a special structure to certify the capability of OCD modeling and library stability, so as to improve the measurement performance as much as possible. In this paper, we selected a 2-D Sigma Shape PMOS Silicon Recess (Σ-PSR) structure for the OCD modeling evaluation and established a certification procedure as well as a relevant evaluation method, which includes the design of DOE (Design of Experiment) wafers, the handbook for data collections, the scoreboard for OCD result analysis for verifying both OCD 2-D modeling performance and library stability. The DOE wafers were processed to form different PSR structures such as total silicon recess depth, sigma height, pull back, tip-off-gate, undercut, and spacer width splits, etc. There are 17-output required parameters for the OCD modeling. At least, 9 floating parameters are necessary to build the Σ-PSR model. The accuracy of the DOE trend and the precision, stability, and GRR (Gauge Repeatability and Reproducibility) of all output parameters were analyzed to evaluate the capability of the OCD modeling. TEM data were also collected to demonstrate the OCD performance of Σ-PSR profile monitor. Finally, we summarized the evaluation method and discussed the future OCD certification work by advanced reference metrology tools.

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“…We ever presented the method to form a bowing-shaped silicon cavity by means of a two-step dry etch process in CSTIC 2012 [4] . As shown in Fig.…”

Section: Link Between Dry Etch Based Silicon Recess and Pet Based Sil...mentioning

confidence: 99%

“…In this work, the experiments were designed to quantitatively study the formation of sigma-shaped silicon recess. Firstly, several dry etch based silicon recesses were formed via the proposed [4] two-step dry etch process to deliver the cavities with different shapes marked with trench depth, tip depth and tip proximity. Secondly, all the above three key parameters were checked again after PET and compared with their pre-PET performance.…”

Section: Link Between Dry Etch Based Silicon Recess and Pet Based Sil...mentioning

confidence: 99%

A Study of Sigma-Shaped Silicon Trench Formation

et al. 2013

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The strict shape control of sigma-shaped silicon trench has to leverage the dry etch process coupled with the appropriate post-etch treatment (PET). Here we addressed the strong link between the shape of dry etch based silicon recess and its effect on the definition of final sigma-shaped trench. Experiment results indicate the critical physical parameters of final sigma-shape silicon trench could be predicted by means of geometry analysis and monitoring dry etching related recess in bulk silicon. Besides, we also noticed the effect of pattern-dependent depth loading at dense areas. Organic polymer generated during etch process tends to introduce the trench depth variation. Polymer lean etch process has been proven as one of effective knobs to overcome such loading to some extent. In addition, the oxidation capacity of post-etch treatment can not be ignored. The ultra-thin silicon oxide film on silicon trench sidewall must be completely removed by dilute hydrofluoric acid before PET to avoid the possible trench depth loading.

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A Study of Dry Etching Process for Sigma-Shaped Si Recess

Cited by 4 publications

References 2 publications

Strained p-Channel MOSFET Fabrication Challenge and Perspective for the 28-Nm Technology Node and Beyond

Strained p-Channel MOSFET Fabrication Challenge and Perspective for the 28-Nm Technology Node and Beyond

2-D Modeling Capability Certification of Optical Critical Dimension (OCD) Metrology Tool by Sigma Shape PMOS Silicon Recess Structure

A Study of Sigma-Shaped Silicon Trench Formation

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