For fine patterning, there are two possible hard mask integration schemes: quad-layer and tri-layer systems. Due to the different structures and processes between quad- and tri- layer systems, each system needs specific chemical and physical properties of the hard mask. In this paper, we report the properties of the carbon-based spin-on hard mask (CSOH) candidates for various hard mask integrations.
KEYWORDS: Reflectivity, Metals, Line width roughness, Logic devices, Multilayers, Etching, Lithography, Control systems, Immersion lithography, Back end of line
Reflectivity control through angle is challenging at hyper NA, especially for Logic
devices which have various pitches in the same layer. A multilayer antireflectant system
is required to control complex reflectivity resulting from various incident angles. In our
previous works, we showed the successful optimization of multilayer antireflectant
systems at hyper NA for BEOL layers. In this paper, we show the optimization of new
multilayer bottom anti-reflectant systems to meet new process requirements at 28nm
node Logic device. During the manufacturing process, rework process is necessary when
critical dimension or overlay doesn't meet the specifications. Some substrates are
sensitive to the rework process. As a result, litho performance including the line width
roughness (LWR) could change. The optimizations have been done on various stack
options to improve LWR. An immersion tool at 1.35NA was used to perform lithography
tests. Simulation was performed using ProlithTM software.
Wan-Ju Tseng, Wen Liang Huang, Bill Lin, Bo Jou Lu, Tsung Ju Yeh, E. T. Liu, Chun Chi Yu, Sue Ryeon Kim, Jeong Yun Yu, Gerald Wayton, Sook Lee, Sabrina Wong, Chaoyang Lin, Maurizio Ciambra, Suzanne Coley, David Praseuth, Kathleen O'Connell, George Barclay
Reflectivity control through angle is challenging at hyper NA, especially for Logic devices which have various
pitches in the same layer. When patterning critical layers, a multilayer antireflectant system is required in order
to control complex reflectivity resulting from various incident angles. Multilayer antireflectants typically consist
of an organic and inorganic (TiN and SiON) layers. Fewer or thinner layers are desired for etch pattern transfer.
However, it would make the reflectivity control through angle more difficult. We have investigated several
antireflectants for a simplified multilayer stack. The organic films differ in terms of n, k, thickness and etch rate.
The n, k, and thickness span the ranges of 1.60-1.85, 0.15-0.30, and 30-130nm, respectively. The overall
patterning performance including profiles, line width roughness (LWR), overlap depth of focus margin (ODOF)
and critical dimension uniformity (CDU) has been evaluated. An immersion tool at 1.35NA was used to perform
lithography. Simulation was performed using ProlithTM software.
When patterning critical layers at hyper NA, a multilayer antireflectant system is required in order to control
complex reflectivity resulting from various incident angles. Multilayer antireflectants typically consist of an
organic antireflectant and inorganic substrates. However, there are still some applications which need a single
organic antireflectant over high reflective substrates. A 2P2E application in double patterning is one of them.
Even though the pitch for double patterning is relatively loose, the reflectivity control is still challenging in terms
of profiles and overall process window. The optical constants and thickness of antireflectants should be well
optimized depending on applications. We have investigated several organic antireflectants for a single
antireflectant over high reflective substrates. The organic films differ in terms of n, k, thickness to cover both the
1st minimum and the 2nd minimum applications. The overall patterning performance including profiles and
process window has been evaluated. ASML 1900i was used to perform lithography. Simulation was performed
using ProlithTM software.
A new dual bottom antireflectant consisting of an organic antireflectant and a SixOyNz:H (SiON) layer has been designed for metal layers to cover both 45nm and 32nm node logic devices. Simulations have been used to optimize the optical constants of the organic antireflectant. The new antireflectant system has been evaluated on a 1.2NA tool for metal layers. The same organic antireflectant has been successfully applied to via layers at a different thickness. The overall patterning performance including profiles, line width roughness (LWR), overlap depth of focus margin (ODOF) and critical dimension (CD) uniformity before and after etch has been evaluated. The new antireflectant system meets all the patterning requirements for a manufacturable process. An immersion tool at 1.2NA was used to perform lithography tests. Simulation was performed by using ProlithTM software.
There are many considerations to the design of BARC materials. Among those many properties, one important property that can effect lithographic performance is BARC coating uniformity. In general, the basic coating property (conformal or planar) depends on basic characteristics of polymer (Mw, chemistry, etc). But another major factor to control the coating uniformity is the choice of solvent system in the formulation of the BARC. According to our experimental results, two major factors that can affect the coating uniformity of one BARC are the vapor pressure and the hydrophilicity of solvents. If any solvent has too high vapor pressure and high hydrophilicity relatively, polymer segregation occurs in BARC surface area in case of high humidity condition, resulted in bad coating uniformity.
In this paper, we will show basic evaluation results including the morphology change of BARC surface with several solvents which can be used in BARC formulation according to various humidity and temperature conditions. And also we will show the solution to overcome this problem in device manufacturing.
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