Double exposure (DE) and double patterning (DP) have emerged as leading candidates to fill the technology gap
between water immersion and EUV lithography. Various approaches of them are proposed to achieve 3x-nm half-pitch
dense lines and beyond. Both DE with two resist processes and double patterning (DP) require two separate exposures,
and they are faced very tight overlay margin by the scanner tool. By contrast, self-aligned double patterning (SADP)
requires one exposure only, and provides high feasibility for 3x-nm node at this moment. However, a sequential order of
multiple non-lithographic steps (film deposition, etch, and CMP) cause a complicated and expensive process of SADP.
Instead of using complicated sacrificial layers, the spacers are directly formed at the sidewall of the resist patterns by
low-temperature CVD deposition or spin on sidewall (SoS) material coating. In this paper, lower cost-of-ownership of
SoS material are studied for SADP process.
Double patterning process with ArF immersion lithography has been developed as one of the most promising candidate
for hp32 node and beyond. However complicated process flow and cost of ownership are the critical issue for this
process. LELE (Litho-Etch-Litho-Etch) is the one of the standard process, but in order to reduce the process and cost,
that LFLE(Litho-Freezing-Litho-Etch) and LLE (Litho-Litho-Etch) process have been investigated as the alternative
process. In these processes, Organic Bottom-Anti-Reflective coating (BARC) is used two times with same film in both
1<sup>st</sup> Litho and 2<sup>nd</sup> Lithography process. In 2<sup>nd</sup> Lithography process, resist pattern will be printed at space area where
exposed and developed in 1<sup>st</sup> lithography process. Therefore, organic BARC needs to have process stability in Photo and
development step to keep good litho performance between 1<sup>st</sup> and 2<sup>nd</sup> lithography in LFLE / LLE process.
This paper describes the process impact of 1<sup>st</sup> exposure and development for organic BARC, and the LFLE / LLE
performance with optimized organic BARC will be discussed.
193nm immersion and Hyper NA lithography are used at 45nm and beyond. The next generation of lithography will use a new technology such as Double Pattering, EUV or EB. Double patterning is one of the currently acceptable technologies.
Three common double pattern techniques are Litho-Etch-Litho-Etch (LELE), freezing, and sidewall (spacer) process. From a technical standpoint LELE is a very promising process, except for the second litho alignment. However, the cost of ownership will be very high because LELE will cost about twice as much as the current single litho patterning process. In order to build up a suitable double patterning technique, many device makers are developing unique processes. Two of these processes are freezing and sidewall. Flash memory makers are diligently investigating the sidewall process by CVD. This is because of the lack of a second litho alignment step, even with its high cost. The high cost of the CVD process can be reduced if a spin on material is used.
One of the goals of this paper is to reduce the cost of ownership by using spin on coatings for the sidewall process. Currently we are investigating this approach to control the sidewall width, profile and other properties.
193nm immersion Lithography will be installed at 45nm and beyond. For severe CD control, BARC (Bottom Antireflective
Coating) has been used and this material must be used for immersion lithography.
So far, we have developed several BARCs with various advantages (fast etch rate, broad resist compatibility, high
adhesion, conformal...etc). Especially in an immersion process, development of BARC has to satisfy for the optical
control and defectivity.
The reflectivity control at Hyper NA is not same as the lower NA, because optical pass length in the BARC is not the
same between low NA and High NA. In order to achieve enough etch selectivity to the substrate, hard mask materials are
necessary. These under layers have absorption at 193nm. As a result of simulation, target optical parameters of next
BARC should be low k value (k = ~0.25) for multi BARC stack.
On the other hand, the defect issue must be decreased in the immersion process. However, the generation of many
kinds of defects is suspected in the immersion process (water mark, blob defect, sublimation defect...etc). Regarding the
BARC, there are also several specific defects in this process. Especially, after edge bead rinse, film peeling at edge area
is one of the concerns. We researched the root cause of edge peeling and a solution for this defect.
In this paper, we will discuss the detail of our BARC approach for litho performance, optical parameter, leaching,
sublimation, edge peel defects and etch selectivity, and introduce new BARC for 193nm immersion lithography.
We found a new polymer platform for ArF BARC that can be prepared by addition polymerization. This system not only improves resist pattern collapse, but also allows control of the optimum film thickness, and etch rate by combination of compounds, method of polymerization (molecular weight control), and additives. Moreover, these materials have the unique characteristic that the resist profiles change little even if the type of resist changes.