EUV resists comprised of main group organometallic oligomeric materials

Abstract

We present the synthesis and preliminary lithographic evaluation of Molecular Organometallic Resists for EUV (MORE) that contain post transition metals. These post transition metal nuclei have high EUV optical density so they can utilize a high fraction of the incident photons. We will describe two technical approaches for EUV resist platforms that contain bismuth. Approach 1: Combination of organometallic compounds with photoacid generators. Approach 2: Combination of high-oxidation state metal-center oligomers that utilize carboxylate anions bound to the metal centers. I. Introduction.As the microelectronics industry continues to follow Moore's law, increasing strain has been placed on today's photoresists systems. With 22-nm gate-lengths currently in production, many chip manufacturers are looking for ways to implement the 16 and 10-nm lithography nodes. Chip manufacturers currently use 193-nm scanners for printing these features, however, these systems have already surpassed their resolution capabilities and imaging is only made possible by multiple patterning. Extreme ultraviolet (EUV, 13.5-nm wavelength) lithography is thought to be the next imaging technology for fabricating microelectronic devices, however, there are still many obstacles that must be overcome. The traditional, chemically-amplified photoresist systems which have been successful in lithography since the 1980's are finally encountering extremely challenging 1 hurdles: poor photon absorption in thin-films, 2 moderate etch selectivity 2,3 and limited gains in resolution. 4,5 Recently, two novel resist systems have been developed based on hafnium-oxide nanoparticles. 6 Researchers at Inpria Co., have demonstrated high resolution EUV resists capable of 8 nm dense line and space patterns at 200 mJ/cm 2 . Christopher Ober's group at Cornell have demonstrated good sensitivity of 12 mJ/cm 2 at modest resolution of 36 nm. This pioneering work has demonstrated the great potential of inorganic systems as photoresists.In this paper, we present on a subset of Molecular Organometallic Resists for EUV (MORE) that are comprised of organometallic compounds containing main group metals. The MORE approach utilises high EUV optical density metals to increase the photon absorbance of thin resist films. James Thackeray in his 2011 SPIE plenary presentation stated that the target absorption for EUV resist films is 50%. To print 10-nm lines with an aspect ratio of 2:1, film thickness must be around 20 nm. Polyhydroxystyrene at this thickness will stop only ~10% of the light (T ≅ 0.90). 7 Loading organic polymers with fluorine will have limited impact. Teflon ((C 2 F 4 ) n ) probably contains the most fluorine possible in an organic polymer,

Reactivity of metal-oxalate EUV resists as a function of the central metal

“…Two resists, NP3 and NP4, were not measured, but a value is reported based on the measurement of NP1 and the CXRO database assuming the same density as NP1 16 . Metal carboxylate based photoresists [3][4][5][6] , JP-19 and JP-20, which contain a bismuth center and an antimony center respectively, are also shown for reference. These two photoresists (JP-19 and JP-20) contain darker metal centers when compared to all other photoresists studied and this is reflected by the data shown in Fig.…”

“…In extreme ultraviolet (EUV) lithography, line-width roughness (LWR) and line-edge roughness (LER) are dominated by resist stochastics, which can be improved by increasing the number of photons absorbed. To improve EUV absorption, metal-based resists were created by research groups around the world [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] . The Molecular Organometallic Resists for EUV (MORE) project utilizes the high absorbance of certain metals by incorporating these elements in photoresists [1][2][3][4][5][6][7][8][9][10] .…”

“…To improve EUV absorption, metal-based resists were created by research groups around the world [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] . The Molecular Organometallic Resists for EUV (MORE) project utilizes the high absorbance of certain metals by incorporating these elements in photoresists [1][2][3][4][5][6][7][8][9][10] . Conventional EUV resists are chemically amplified, which are composed of mostly organic elements such as carbon, hydrogen, and oxygen.…”

Isotopic Labeling Studies of EUV Photoresists Containing Antimony

“…The Ober group has demonstrated zirconium and hafnium nanoparticle photoresists capable of high resolution and improved etch resistance [9]. Additionally, our group has explored and evaluated resists composed of metals including cobalt, platinum, tin, antimony and bismuth [10][11][12][13][14][15].…”

New approach to improve LER of EUV resist pattern by chemical and thermal treatment

“…[3] [4] To overcome this limitation, modifications of resists have been attempted, including polymer bound PAGs resist, Molecular resist, or Metallic resist. [5][6] [7] Aside from resist modification itself, there are different approaches to improve lithography performance, including sensitivity improvement by assistance of under layer and roughness improvement by resist thermal flow. [8] There is another approach to improve pattern roughness, which incorporates some treatment after the resist pattern formation.…”