Resist deconstruction as a probe for innate material roughness

Fedynyshyn, Theodore H.

doi:10.1117/1.2408410

Cited by 9 publications

(6 citation statements)

References 18 publications

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“…Resist films at different stages of the lithography sequence or at different processing conditions were studied. More details about the RR DP technique were published earlier [7][8][9][10][11].…”

Section: Methodsmentioning

confidence: 99%

“…Triphenylsulfonium salt 4-(methacryloxy)benzenesulfonate (MBS-TPS) was likewise prepared by the method of Gonsalves by reacting sodium 4-phenosulfonate and metharylic acid [9].…”

Section: Methodsmentioning

confidence: 99%

“…This method involves performing a contrast curve and measuring the resulting film roughness with differing degrees of film loss. This technique allowed for the identification of the PAG as a major contributor to IMR [8,9]. Further work identified the inhibition properties of the PAG coupled with PAG segregation during post exposure bake step as significant contributors of IMR and by inference of LWR [10].…”

Section: Introductionmentioning

confidence: 99%

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Resist roughness bi-modality as revealed by two-dimensional FFT 2D analysis

Gotkis

Baranov

Fedynyshyn

et al. 2009

Advances in Resist Materials and Processing Technology XXVI

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LER/LWR performance is currently considered as one of the major stumbling blocks complicating progress in the semiconductor technology. Line edge scans show that low frequency components clearly dominate the LER Power Spectral Density (PSD), thus implying a large characteristic length (>100-500 nm) phenomenon as the major LER source.Most of the theoretical analyses aimed to identify the origin of the LER were focused on the combined effect of exposure and CAR action statistics, and failed to explain the origin of this limit, which resulted in suggestions that there is more than just one phenomenon involved in LER generation.Depth profiling experiments were performed for a broad set of Polymer-PAG-Base combinations. Depth profiling PSD spectra have demonstrated that higher RMS values and correspondingly higher PSD amplitudes are associated with tighter PSD spectrum shifted towards lower frequencies (larger sizes of roughness features), which is very typical for all the cases investigated. The set of the PSD spectra obtained exhibit a pronounced bi-modal structure, indicating that there are at least two clearly noticeable independent roughness-controlling mechanisms.

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Section: Methodsmentioning

confidence: 99%

“…Triphenylsulfonium salt 4-(methacryloxy)benzenesulfonate (MBS-TPS) was likewise prepared by the method of Gonsalves by reacting sodium 4-phenosulfonate and metharylic acid [9].…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Resist roughness bi-modality as revealed by two-dimensional FFT 2D analysis

Gotkis

Baranov

Fedynyshyn

et al. 2009

Advances in Resist Materials and Processing Technology XXVI

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“…These polymers have been described previously [12][13][14][15] and are presented in Table 2. Typical PAG and base quencher loading levels were used.…”

Section: Resist Codementioning

confidence: 99%

Sensitivity of EUV resists to out-of-band radiation

Roberts

Bristol

Younkin

et al. 2009

Advances in Resist Materials and Processing Technology XXVI

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Here we present the relative sensitivity of EUV resists to out of band radiation (OOB), specifically wavelengths in the range 157 -400 nm. EUV light sources have specifications limiting the allowed energy output in that spectral range yet there is little data supporting the specified values. Filters might be required to meet the spectral purity specifications which will likely have the detrimental effect of reducing the in-band radiation at 13.5 nm and therefore negatively impact the cost of ownership of EUV lithography. To better quantify the effects of OOB we obtained contrast curves and absorbance spectra for several EUV resist platforms at nine exposure wavelengths. The 2007 ITRS Roadmap suggests that resist thicknesses will be near 35 -65 nm when EUV will be used 1 . We found that, in this optically thin regime, resist sensitivity increases with increasing absorbance. The sensitivity decreases dramatically for wavelengths approaching 300 nm, and is negligible for longer wavelengths. The OOB sensitivity of the resists examined can be estimated to within an order of magnitude using the resist absorbance value. For resists with absorbance values on the same order of magnitude, sensitivity is determined by other aspects of the resist formulation. Within the wavelength region explored, the greatest concern is near 160 -240 nm based on current resist sensitivity characteristics. However, there is a gap in data between 13.5 -157 nm and there may be other reasons to limit the source output in that wavelength range. The data presented here could be useful in setting or modifying the OOB specifications for EUV tools.Keywords: Extreme Ultraviolet Lithography, EUVL, Resist, Sensitivity, out-of-band, spectral purity INTRODUCTIONEUV Lithography is being developed as a potential successor to 193 nm lithography for printing the smallest microprocessor features 2 . Resists developed for EUV are typically based on modifications to materials developed for other lithographic exposures, specifically 248 nm, 193 nm, and e-beam 3 . Therefore, EUV resists are sensitive to radiation other than 13.5 nm, as has been demonstrated [4][5][6] . EUV sources produce light over a wide spectral range [7][8][9][10] . The multilayer coated (MLC) mirrors used in the optics are effective at narrowing the EUV spectral output to peak at 13.5 nm with a bandwidth of ±2%. However, the mirrors also reflect other wavelengths. If OOB light produced by the source reaches the wafer plane, and the resist is sensitive to that light, then contrast will be reduced resulting in degraded imaging performance 6 . The purpose of this study is to characterize the sensitivity of typical EUV resists to OOB radiation. Mbanao et al. measured the sensitivity of 4 resists in the spectral range 190-650 nm 5 . The study presented here extends the spectral range down to 157 nm and includes a wider breadth of resist types with data collected on 13 different materials. Moreover, all resists in this study were 60 nm thick (which is expected to be relevant when EUV is i...

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“…This technique allowed for the identification of the PAG as a major contributor to IMR. 11,12 Further work identified the inhibition properties of the PAG coupled with PAG segregation during post exposure bake step as significant contributors of IMR and by inference of LWR. 13 A correlation between atomic force microscope (AFM) and chemical force microscope (CFM) responses provided direct evidence that PAG segregation occurred and that this segregation was responsible for the observed film surface roughness.…”

Section: Introductionmentioning

confidence: 99%

PAG segregation during exposure affecting innate material roughness

et al. 2007

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We have developed an improved AFM-based technique to measure intrinsic material roughness (IMR) after base development. We have investigated the contribution of different polymeric PAGs to IMR. These polymeric PAGs include copolymers of several styrenic PAGs with hydroxystyrene. The IMR of these polymer-bound PAGs is reduced relative to that of their nonpolymeric counterparts with DUV exposure. Theses results represent further evidence for PAG segregation during the bake steps as being responsible for increased IMR in exposed resists, presumably by increasing the dissolution rate inhomogeneity on a nano-scale level. The work also shows that the effects of PAG segregation can be mitigated by employing polymer-bound PAGs.

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Resist deconstruction as a probe for innate material roughness

Cited by 9 publications

References 18 publications

Resist roughness bi-modality as revealed by two-dimensional FFT 2D analysis

Resist roughness bi-modality as revealed by two-dimensional FFT 2D analysis

Sensitivity of EUV resists to out-of-band radiation

PAG segregation during exposure affecting innate material roughness

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