Real-time ultraviolet ellipsometry monitoring of gate patterning in a high-density plasma

Vallon, S.; Joubert, O.; Vallier, L.; Ferrieu, F.; Drévillon, B.; Blayo, N.

doi:10.1116/1.580722

Cited by 10 publications

(3 citation statements)

References 3 publications

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“…Other groups used SE for real-time feedback control of thermal chlorine etching of GaAs and plasma etching of silicon nitride films (245), and control of wet etching of GaAs/AlGaAs (246). SE analysis during etching of patterned films is becoming evermore important (247,248), including that of poly-Si gates (247), TiN and polysilicon (249), and GaAs (250). The same characteristic ellipsometric signature was seen as for unpatterned films, suggesting potential for process control.…”

Section: Ellipsometrymentioning

confidence: 99%

Optical Diagnostics for Thin Film Processing

Herman

2003

Annu. Rev. Phys. Chem.

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Optical diagnostics are used to probe the plasma or neutral gas above the substrate, particles in the gas or on the surface, the film surface and reactor walls, the film itself, and the substrate during thin film processing. The development and application of optical probes are highlighted, in particular for analyzing plasma/gas phase intermediates and products and film composition, and performing metrology, thermometry, and endpoint detection and control. Probing etching (particularly plasma etching) and deposition (particularly epitaxy) are emphasized.

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Section: Ellipsometrymentioning

confidence: 99%

Optical Diagnostics for Thin Film Processing

Herman

2003

Annu. Rev. Phys. Chem.

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“…[23][24][25][26][27][28][29] Several excellent references describe the principles, operation, and instrumentation of various ellipsometric systems, [30][31][32][33][34] both for single wavelength and multiple wavelength ͑spectral͒ systems. Ellipsometry is a common optical technique for the characterization of thin films and for surface diagnostics, though its use in etch monitoring is less well documented.…”

Section: Real-time Spectroscopic Ellipsometrymentioning

confidence: 99%

Compensation for transient chamber wall condition using real-time plasma density feedback control in an inductively coupled plasma etcher

Klimecky

Grizzle

Terry

2003

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Articles you may be interested inSurface loss rates of H and Cl radicals in an inductively coupled plasma etcher derived from time-resolved electron density and optical emission measurements J. Vac. Sci. Technol. A 28, 360 (2010); 10.1116/1.3330766Feedback control of plasma electron density and ion energy in an inductively coupled plasma etcher Real-time control of ion density and ion energy in chlorine inductively coupled plasma etch processing Reactive ion etch processing is known to exhibit significant variability in final etch performance due to wall condition. Previous studies have shown that neutral species transients depend strongly upon chamber seasoning. In this article, we show simultaneous measurements of wall-state-induced changes in plasma density and poly-Si etch rate, and demonstrate a real-time feedback control system that corrects for the plasma density variation. We demonstrate that controlling the plasma density to constant value eliminates the classic ''first wafer effect'' in Cl 2 etching of poly-Si in a Lam 9400 transformer coupled plasma ͑TCP͒. Chamber conditions studied include fluorination/ cleaning by C 2 F 6 plasmas compared to chlorination/deposition from Cl 2 plasmas. Transient density changes due to wall condition were measured using a microwave resonance cavity technique called broadband rf. Following chamber fluorination, broadband data show a significant drop in electron density ͑ϳ39%͒ from nominal levels. This is followed by subsequent partial recovery of the nominal density during a 60 s Cl 2 etch. Independent measurements correlate strongly with the broadband signals; particularly real-time poly-Si etch rate and SiCl 4 etch product concentration. Observed real-time variations in all signals were then compensated using a single input/single output proportional-integral ͑PI͒ feedback control algorithm, in which the broadband peak frequency is the system output variable and TCP power is the system actuator. Such PI control not only stabilizes broadband peak frequencies, but also steadies poly-Si real-time etch rate and SiCl 4 etch product concentration. This compensation scheme is then applied over multiple runs to reduce etch depth variability due to chamber condition. Results of this control system are shown to attenuate first wafer effects by a factor of 3 and reduce overall etch depth variation from run to run by an additional 33% compared to standard manufacturing practice. When applied to patterned wafer etches, feedback control of plasma density with an oxide hardmask is found not to alter critical dimensions or profile in any observable way. Only total etch depth appears to be affected using density control, as the real-time etch rate is in general increased in comparison to open-loop etching.

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“…The ellipsometry is a very powerful technique to monitor the etching of thin films in real time. 19 The DPS + source is also equipped with a powerful endpoint system, EyeD™ from Verity Instrument to allow real time monitoring of the etch process. This system combines two techniques: Interferometry and optical emission from the plasma.…”

Section: Methodsmentioning

confidence: 99%

Plasma etching of HfO2 at elevated temperatures in chlorine-based chemistry

Hélot¹,

Chevolleau²,

Vallier³

et al. 2005

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Plasma etching of HfO 2 at an elevated temperature is investigated in chlorine-based plasmas. Thermodynamic studies are performed in order to determine the most appropriate plasma chemistry. The theoretical calculations show that chlorocarbon gas chemistries ͑such as CCl 4 or Cl 2 -CO͒ can result in the chemical etching of HfO 2 in the 425-625 K temperature range by forming volatile effluents such as HfCl 4 and CO 2 . The etching of HfO 2 is first studied on blanket wafers in a high density Cl 2 -CO plasma under low ion energy bombardment conditions ͑no bias power͒. Etch rates are presented and discussed with respect to the plasma parameters. The evolution of the etch rate as function of temperature follows an Arrhenius law indicating that the etching comes from chemical reactions. The etch rate of HfO 2 is about 110 Å / min at a temperature of 525 K with a selectivity towards SiO 2 of 15. x-ray photoelectron spectroscopy analyses ͑XPS͒ reveal that neither carbon nor chlorine is detected on the HfO 2 surface, whereas a chlorine-rich carbon layer is formed on top of the SiO 2 surface leading to the selectivity between HfO 2 and SiO 2 . A drift of the HfO 2 etch process is observed according to the chamber walls conditioning due to chlorine-rich carbon coatings formed on the chamber walls in a Cl 2 -CO plasma. To get a very reproducible HfO 2 etch process, the best conditioning strategy consists in cleaning the chamber walls with an O 2 plasma between each wafer. The etching of HfO 2 is also performed on patterned wafers using a conventional polysilicon gate. The first result show a slight HfO 2 foot at the bottom of the gate and the presence of hafnium oxide-based residues in the active areas.

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Real-time ultraviolet ellipsometry monitoring of gate patterning in a high-density plasma

Cited by 10 publications

References 3 publications

Optical Diagnostics for Thin Film Processing

Optical Diagnostics for Thin Film Processing

Compensation for transient chamber wall condition using real-time plasma density feedback control in an inductively coupled plasma etcher

Plasma etching of HfO2 at elevated temperatures in chlorine-based chemistry

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