Optical lithography in the sub-50-nm regime

The minimum feature size of the semiconductor device will be smaller and smaller because of the increasing demand for the high integration of the device. According to recently proposed roadmap, ArF immersion lithography will be used for 65 nm to 45 nm technology nodes. Polarization effect becomes a more important factor due to the increasing demand for high NA optical system and the use of immersion lithography.It is important to know that the polarization effect is induced by mask in small size patterning. The unpolarized plane waves leaving the illumination system are diffracted by the mask. So the light beam going through the mask will experience induced polarization by the mask. In this paper, we considered the change of polarization state as a function of mask properties. We calculated vector diffraction of 193 nm incident light. The masks considered are the chromeless mask, a binary chrome mask and 6 % attenuated phase shifting mask. We use the finite-difference time-domain method to solve the Maxwell equation. The aerial image depends on the polarization states induced by the mask properties such as materials, thickness, and pitch.

show abstract

“…In this region, the light going through mask is completely TM-polarized. So we called 'wide grid zone' [6]. …”

Section: Resultsmentioning

confidence: 99%

Simulation of mask induced polarization effect on imaging in immersion lithography

et al. 2006

View full text Add to dashboard Cite

show abstract

“…In the following, we will vary the linewidth/pitch and the angle of incidence and compute the diffraction efficiency and the phase of the diffraction orders. The diffraction efficiency η m for a certain diffraction order is defined as the ratio between the intensity of the order I m and the intensity of the incident light I 0 : 0 m m I I = η ( 2 ) The polarization performance of the mask is evaluated in terms of the fraction of polarization [2]:…”

Section: Diffraction Analysismentioning

confidence: 99%

Mask modeling in the low k 1 and ultrahigh NA regime: phase and polarization effects (Invited Paper)

Erdmann

2005

SPIE Proceedings

View full text Add to dashboard Cite

This paper reviews state of the art mask modeling for optical lithography. Rigorous electromagnetic field (EMF) simulation of light diffraction from optical masks is compared to the traditional assumption of an infinitely thin mask, the so called Kirchhoff approach. Rigorous EMF simulation will be employed to analyze mask polarization phenomena which become important in the ultrahigh NA regime. Several important lithographic phenomena, which can be explained only with rigorous EMF simulation, are discussed. This includes the printability of small assist features, intensity imbalancing for alternating PSM, and process window deformations. The paper concludes with a discussion on material issues and algorithmic extensions which will be necessary for an accurate modeling of future mask technology.

show abstract

“…As a result, topography effects have a significant influence on the diffraction properties of reticles 1 . This will become even more severe with the emergence of immersion lithography extending imaging to the sub-50nm regime [2][3][4][5][6] . The intensity distribution of the diffracted light is substantially different from the case of an infinitely thin mask, which is often referred to as the Kirchhoff-approximation.…”

Section: Introductionmentioning

confidence: 99%

Investigation of polarization effects on new mask materials

Bubke

Teuber

Hoellein

et al. 2005

Optical Microlithography XVIII

View full text Add to dashboard Cite

As microlithography moves to smaller critical dimensions, structures on reticles reach feature sizes comparable to the operating wavelength. Furthermore, with increasing NA the angle of incidence of light illuminating the mask steadily increases. In particular for immersion lithography this will have severe consequences on the printing behavior of reticles. Polarization effects arise which have an impact on, among other things, the contrast of the printed image. Angular effects have to be considered when aggressive off-axis illumination schemes are used. Whereas numerous articles have been published on those effects and the underlying theory seems to be understood, there is a strong need for experimental verification of properties of real masks at the actinic wavelength. This paper presents measurements of polarization effects on different mask blank types produced at Schott Lithotec including chrome and alternative absorber binary mask blanks, as well as phase shift mask blanks. Thickness and optical dispersion of all layers were determined using grazing incidence x-ray reflectometry (GIXR) and variable angle spectroscopic ellipsometry (VASE). The set of mask blanks was patterned using a special design developed at the Advanced Mask Technology Center (AMTC) to allow measurements at different line width and pitch sizes. VUV Ellipsometry was then used to measure the properties of the structured materials, in particular the intensities in the 0 th and 1 st diffraction order for both polarization directions and varying angle of incidence. The degree of polarization of respective mask types is evaluated for dense lines with varying pitches and duty cycles. The results obtained experimentally are compared with simulations based on rigorous coupled wave analysis (RCWA).

show abstract

Optical lithography in the sub-50-nm regime

Cited by 16 publications

References 1 publication

Simulation of mask induced polarization effect on imaging in immersion lithography

Simulation of mask induced polarization effect on imaging in immersion lithography

Mask modeling in the low k 1 and ultrahigh NA regime: phase and polarization effects (Invited Paper)

Investigation of polarization effects on new mask materials

Contact Info

Product

Resources

About