Corresponding to the ITRS roadmap, EUV Lithography will in the not-too-far future reach the point, where critical resist dimensions are in the same order of magnitude as polymer chains and acid diffusion lengths, while photon energies will largely exceed the binding energies of all organic molecules. Especially in EUV, where secondary electron side reactions may lead to a higher outgassing of polymer fragments than in 157nm and 193nm lithography, outgassing is agreed to be a critical issue for resist development. In this paper EUV, 193nm and 157nm outgassing is characterized using an online mass spectrometer attached to several different outgassing setups (i.e. synchrotron, laser). The total outgassing and the time dependent outgassing of resist fragments has been characterized for a number of resist polymer platforms. The results are compared and discussed in terms of the applied photon energies and differences in EUV, 157nm and 193nm exposures. Time dependent scanning of selected mass channels was used to differentiate if an outgassing fragment had its origin from the photoacid generator (PAG) or from a photolytic or a photochemical reaction of the polymer matrix. For EUV, correlations are given between resist outgassing and high dose crosslinking and scissioning behaviour of EUV resists.
At the 5th NGL Workshop, 28-3OAug200l , the IPL team, headed by Infineon Technologies, has presented overhead foils1 providing an overview of results as achieved with the Ion Projection Lithography Process Development Tool (PDT) which has been developed and realized by IMS-Vienna as part of the 1997-2001 European MEDEA project. Furthermore concepts for a full field (25X25mm2) ion projection stepper and it's wafer throughput potential have been presented.
Stencil masks, based on 150mm Si-wafers, with large diameter membrane fields have been fabricated for use in an ion projection lithography (IPL) tool. With a current membrane diameter of 126mm, the control of pattern placement is one of the major challenges. As the masks are produced by a wafer flow process, pattern distortions after membrane etch, caused by stiffness changes, have to be controlled. Additionally, stress inhomogenity resulting from SOI wafer blank fabrication, boron implantation and other process steps has to be addressed. These parameters will be discussed on a global and local scale. Results by both, experiments and FE modeling simulations are presented.
A short review of the current status of IPL stencil mask development is presented in this paper. Stencil masks based on 6' Si-wafer have been fabricated with a membrane diameter of 126 mm. With a typical membrane thickness of 3 micrometers , mechanical stability is a critical issue. The resulting placement errors have been measured using an LMS IPRO measurement tool and have been compared to Finite Element (FE) calculations simulating the fabrication process. Process-induced distortions can be predicted by FE calculations with an accuracy of up to 24 mm 3(sigma) . In addition to large circular membranes, an alternative geometry has been considered. Masks with a quadratic membrane area of 60 X 60 mm2 show IPDs of 3(sigma) equals 39 nm which are about 4 times smaller than those of large circular membranes. This result agrees well with predictions of FE calculations. In order to protect the Si-mask against ion bombardment, a protective carbon layer is deposited onto the membrane, thus preventing stress changes due to ion implantation. The current status of the carbon deposition process will also be addressed briefly.
Corresponding to characteristics and manufacturing processes of IPL stencil masks, requirements of used resist technologies are determined. Two thin layer imaging (TLI) techniques, the single layer top surface imaging (TSI) and the bilayer CARL (chemical amplification of resist line) have been investigated and compared for stencil mask making. Especially the process design of CARL is discussed in detail. Additionally, a possible process integration of the carbon layer, that is deposited on the stencil mask and protects the membrane against damaging due to ion bombardment, is presented. Finally, results of silicon etching and complete manufactured stencil masks using the developed resist technologies are demonstrated.
Two process flows for the fabrication of stencil masks have been developed. The PN Wafer Flow- and the SOI Wafer Flow Process. Membranes and stencil masks out of different 6 inch Si base wafers with 3 micrometers membrane thickness and a membrane diameter between 120 mm and 126 mm were fabricated. The membrane stress depending on the material property and doping level has been determined. First metrology measurements have been carried out.
Ion beam lithography is one of the most promising future lithography technologies. A helium or hydrogen ion beam illuminates a stencil membrane mask and projects the image with 4X reduction to the wafer. The development of stencil masks is considered to be critical for the success of the new technology. Since 1997, within the European Ion Projection Lithography MEDEA (Microelectronic Devices for European Applications) project silicon stencil masks based on a wafer- flow process are developed. They are produced in a conventional wafer line. Six inch SOI (silicon-on-insulator) wafers are patterned with an e-beam wafer writing tool, then trenches are etched by plasma etching. Afterwards, the membrane is etched by wet etch using the SOI-oxide layer as an etch stop. The last step is to add a coating layer, which is sputtered onto the membrane. It protects the mask against ion irradiation damage. For metrology and inspection, methods used for conventional chromium masks as well as new techniques are investigated. Results from placement measurements on the Leica LMS IPRO tool will be presented. Finally, methods for CD measurement, defect inspection, repair and in-situ-cleaning in the stepper will be discussed, including experimental information of first tests.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.