Comparison of Endpoint Methods in Advanced Photomask Etch Applications

Johnson, D. J.; Plumhoff, Jason; Shin, Jong Gye; Rausa, Emmanuel

doi:10.1117/12.467749

Cited by 3 publications

(2 citation statements)

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“…Although variation in selectivity can change etch bias just like endpoint, most of studies published in the past have been focused on emphasizing the importance of endpointing. [4][5][6][7] One way to keep the critical CD under very stringent targeting control is to adopt thin resist. Thin resist is good for lithography but leaves less room for dry etch process tuning.…”

Section: Introductionmentioning

confidence: 99%

In situ selectivity monitor for dry etch of photomasks

et al. 2009

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A method is described to monitor etch selectivity real time in Applied Materials' advanced Tetra TM mask etcher module. With the built-in Transmission Endpoint (TEP) capability, the transmission information for a wide range of spectra is collected. As resist thickness continues to be reduced during photomask etching process, interference fringes can be observed at selected wavelengths on the TEP spectrum. Based on known value from n & k simulation, the peak/valley positions of interference fringes can be defined. With the help from an algorithm developed to determine the corresponding time for each peak/valley position, the average resist etch rate can be obtained. In addition, the starting and ending resist thickness on the plate being etched can be calculated, so the incoming resist quality can be verified and being monitored. Combined with Cr etch rate derived from the endpoint time with plasma emission spectra, the Cr to photoresist etch selectivity can be monitored for each production plate automatically.

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Section: Introductionmentioning

confidence: 99%

In situ selectivity monitor for dry etch of photomasks

et al. 2009

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“…Laser endpoint detection (EPD) is a popular method that uses the difference of the reflectance of etched films for the laser light 4) . One of advantages of this method is a stability of the spectra observed during etching against the different etching conditions.…”

Section: Introductionmentioning

confidence: 99%

Process monitoring of chrome dry-etching with RF sensor for reticle production beyond 90-nm node

et al. 2003

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In reticle production for 90-nm node generation and beyond, quite strict chrome CD control is strongly demanded. For chrome dry-etching process, establishment of reliable system for chrome endpoint detection is one of critical issues. In this paper, the effectiveness of radio frequency (RF) sensor as a process monitor for chrome dry-etching was examined. As general endpoint detection systems, such as Laser endpoint detection (Laser EPD) and optical emission spectroscopy (OES), the system based on RF sensor shows ability to get chrome endpoint. Experimental data implied its competence as an endpoint detector for the plates of various chrome loads with enough stability and reliability. Moreover, this sensor has an advantage that plasma impedance observed with the sensor has a correlation with etching performance, such as etching bias and its uniformity. This property is useful, because feedback of the variation of sensor output to process condition is able to play important role in control of reticle CD. As a consequence, the concept of advanced process control base on the RF sensor is proposed.

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Photomask plasma etching: A review

Wu¹

2006

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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Investigation of etching properties of metal nitride/high-k gate stacks using inductively coupled plasma Photomask plasma etching was thoroughly reviewed over wide topics including history, equipment, etchant, absorbers, phase shifters, thermodynamics, and kinetics. Plasma etch obtained industrial applications for photomask fabrication in the 1990s and presently is a critical fabrication step for the "enabling" photomask industry. Among all types of photomasks ͑binary, embedded attenuated phase-shift mask, and alternating aperture phase-shift mask͒, chromium ͑Cr͒ containing material etching has been the basis and fundamental for all photomask etches. The main technological challenges for Cr etch occur on ͑isolated͒ dark features of a high load photomask due to the etch critical dimension ͑CD͒ bias dependence on the local loading. It determines the CD features on the Cr layer, phase shifter MoSi layer, and fused silica ͑quartz͒ layer. The CD deviation on pattern layers from the nominal value has been a challenge, especially for the Cr state-of-the-art 65 nm node photomasks even though data sizing exists. Inductively coupled plasma plus bias power using radio frequency wavelength is the dominant configuration of the photomask plasma etcher, with improved loading and CD mean-to-target potential. Thermodynamic applications ͑Gibbs energy minimization method͒ on photomask plasma etch provide a quick, easy, and low cost method to estimate the plasma etch feasibility and defect reduction at different plasma gas input conditions. Empirical relationships between operational parameters and etch properties significantly improve the only design of experiment procedure for etch process optimization.

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Comparison of Endpoint Methods in Advanced Photomask Etch Applications

Cited by 3 publications

References 0 publications

In situ selectivity monitor for dry etch of photomasks

In situ selectivity monitor for dry etch of photomasks

Process monitoring of chrome dry-etching with RF sensor for reticle production beyond 90-nm node

Photomask plasma etching: A review

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