Naomichi Abe

Alicyclic polymer for ArF and KrF excimer resist based on chemical amplification

We designed a new chemical amplification resist for ArF and KrF excimer lithography. The resist comprises alicyclic the copolymer of adamantylmethacrylate and tert-butylmethacrylate, with triphenylsulfonium hexafluoroantimonate as a photo acid generator. This resist is highly transparent at KrF and ArF wavelengths because it has no aromatic and its dry etch resistance is comparable to that of a Novolac resist. The lithographic performance of this resist was evaluated using a KrF excimer laser stepper. A less than 0.5 micron line and space pattern profile was obtained with our resist.

Evaluation of chemically amplified resist based on adamantyl methacrylate for 193-nm lithography

An ArF single layer resist based on alicyclic polymer has been developed. Our work centers on improving the solubility of the base polymer in an aqueous base solution. The solubility is the most significant point in using alicyclic polymer. A suitable developer is obtained by adding isopropyl alcohol to the standard TMAH solution with a proper mixing ratio. This mixture greatly enhances the dissolution rate and allows the alicyclic polymer to act as a highly sensitive resist. Over-top coating has also been used to improve the pattern profile. We applied these processes to a resist based on a copolymer of 3-oxocyclohexyl methacrylate and adamantyl methacrylate. The results of ArF lithography are encouraging. There is a high sensitivity of about 10 mJ/cm2, and a high resolution of 0.17 micrometers lines and spaces is achieved. This shows that by enhancing the solubility the lithographic characteristics of the resist based on the alicyclic polymer are effectively improved.

Dry development of the top imaging layer for bilayer system in the down stream of O2/CF4 plasma

We investigated dry-develop resist as the top layer in a bilayer system. The resist consisted of polyacetylene with silicon atoms, PTMDSO (poly 4,4,7,74etramethyl-4,7-disila- 2-octyne) as a base polymer, and a phenyl azide as a photosensitive addition agent. 0.30 pm line and space negative patterns were resolved, when the resist exposed using a KrF excimer laser stepper system was developed in the down stream of 02/CF4 plasma. The sensitivity was around 100 mJ/cm2 and the oxygen plasma resistance was about 50 times greater than that of novolak resist.

Effect of reducing the contaminant concentration when patterning a chemically amplified positive resist

We considered that contaminant control could best be addressed from the processing side. A KrF excimer stepper and a track system were physically integrated and equipped with chemical filter units. The atmosphere where wafers were transported from exposure to postexposure bake (PEB) was enclosed. The measured ammonia concentration was always less than 0.5 (mu) g/m3 everywhere within the enclosed atmosphere. We patterned resists with an ammonia concentration of 0.2 (mu) g/m3. They showed no T-tops and the deviation rates of line width against PEB were within the range of 0.56 to 0.80 nm/min for line and space patterns between 0.30 to 0.35 micrometers . These low deviation rates were considered to be acceptable for manufacturing purposes.