As patterning of implant layers becomes increasingly challenging it is clear that the standard resist/Top Antireflective
Coating (TARC) process may be soon be limited in terms of its ability to meet implant targets at future nodes. A
particularly attractive solution for patterning implant levels is the use of a Developable Bottom Anti-Reflective Coating
(DBARC). Similar to a conventional BARC, a DBARC controls reflectivity from the underlying substrate by absorbing
the incident radiation thereby minimizing detrimental effects of reflected light. However, unlike a conventional Bottom
Anti-Reflective Coating (BARC) which requires a BARC open etch step, the DBARC is developed with the resist in a
single step leaving the substrate ready for implantation. These properties make DBARC very attractive for implant
In this paper, we report on the development of KrF and ArF DBARCs for implant applications. Our primary interest is
in developing solutions for patterning Post-Gate implant levels. We briefly describe our fundamental design concepts
and demonstrate the concepts are robust as we develop AR<sup>TM</sup>602 DBARC to address the criteria for a production worthy
DBARC. This includes data on EBR performance, drain line compatibility, sublimation and footing coverage over
topography. In terms of lithographic performance, we demonstrate improved capability over the incumbent SLR/TARC
process in many key areas. This includes through pitch performance, process window and profile integrity over
topography for both KrF and ArF DBARC solutions. Several strategies to enhance profile by resist/DBARC matching
are also demonstrated. From a platform robustness standpoint, we show that AR602 DBARC is ready for high volume
manufacturing in terms of batch to batch control and shelf life.
Developable bottom anti-reflective coating (DBARC) technology holds promise in two main areas of lithography. The
first application of DBARC is in implant lithography where patterning implant levels would greatly benefit from
improved reflection control such as provided by a conventional BARC. However, implant layers cannot withstand
BARC open etch thereby making DBARC an attractive solution as the resist and DBARC are simultaneously dissolved
during the development step leaving the underlying substrate ready for implantation. In comparison to current implant
processes with top anti-reflective coatings (TARC), DBARCs are anticipated to offer improvements in reflection control
which would translate to improved CDU and increased process window for both KrF and ArF implants. Indeed, this area
has long been considered the ideal insertion point for DBARC technology.
The second area where DBARC technology can make a significant impact is in non-implant lithography. In this large
segment, the ability to replace a conventional BARC with a DBARC affords the device maker the ability to simplify
both lithographic and integration processes. By replacing the BARC with a DBARC, the BARC open etch is negated.
Furthermore, by applying this strategy on multilayer stacks it is possible to greatly simplify the process by avoiding both
CVD steps and pattern transfer steps thereby easing integration. In this area, DBARC technology could have merit for
low k1 KrF and ArF (dry) lithography as well as in immersion ArF processes.
This paper describes our results in designing production worthy DBARCs for both implant and non-implant applications.
A newly developed KrF DBARC platform is evaluated for logic implant applications and compared to a standard TARC
implant process. Post develop residue and defectivity are checked for the new platform and the results compared to
production worthy BARC and implant resists. A new ArF platform was also developed and initial lithographic results
are reported for an implant application. Several non-implant applications were also investigated and results are reported
for high resolution KrF and ArF (dry) lithography as well as an immersion ArF process.
The minimum design rule of device patterns for LSI implant layers has been shrinking constantly according to the
industry requirements. Wavelength has been shortened and numerical aperture (NA) of the scanner has been enlarged to
catch up with the required shrinkage. Implant layers are unique because the resist is nearly always used without an
antireflective coating, and as a result, the resist is in direct contact with a multitude of substrate materials. In implant
applications, the wafer topography sacrifices some of the lithographic performance in order to obtain adequate features
on both top and bottom of the topography. KrF lithography has applied to most of the ion implant levels at today's
To solve the several issues in ion implant process, New KrF resist was designed specifically for the lithographic /
implantation process requirements.