We report on a lithographic study of the behavior of non- cholate tert-butylcarboxylate dissolution inhibitor (DI's) formulated in a poly(norbornene/maleic anhydride/acrylic acid/tert-butyl acrylate) 193 nm single layer resin. A comparision is made between formulations containing non- cholate DI's, cholate based DI's and formulations containing blends of the two different types of DI's. It was found that formulations containing the non-cholate materials tended to give T-topped profiles while the formulations containing cholate based materials and blends containing as little as 1% cholate based DI did not.
Glass transition measurements of cycloolefin/maleic anhydride (COMA) resist resins are complicated by the fact that their glass transitions and the thermal decomposition of their imaging groups often occur over the same temperature range. In order to gain insight into the Tg ranges of these materials, a series of model non-imaging COMA polymers was synthesized and evaluated by DSC. Among the materials thus examined were copolymers of substituted norbornenes with maleic anhydride, copolymers of nobornene with maleic anhydride and cyclohexyl acrylate, and copolymers of vinyl ethers with maleic anhydride. The effects of cholate additives on thermal properties of COMA polymers were also examined.
We report on a study of the chemical and lithographic behavior of two types of base additives. One class of materials that we will report on are aminosulfonate onium salts, we report a study of both the thermal stability and the lithographic behavior imparted by these as a function of chemical structure. It will be shown that the decomposition temperature is a function of the basicity (nucleophilicity) of the counter anion but this can be countered by appropriate choice on onium cation. We will also discuss the lithographic performance of formulations containing transparent ammonium carboxylate bases. It will be shown that these materials provide for comparable lithographic to a standard formulation containing an amine additive. Since carboxylates and aminosulfonates are far less nucleophilic than amine additives these additives may be useful because they will not have the tendency to interact with electrophilic sites such as maleic anhydride derived repeat units.
Post exposure bake (PEB) models in the STORM program have been extended to study pattern formation in 193 nm chemically amplified resists. Applications to resists formulated with cycloolefin-maleic anhydride copolymers, cholate based dissolution inhibitor, nonaflate photoacid generator and base quencher are presented. The PEB modeling is based on the chemical and physical mechanisms including the thermally induced deprotection reaction, acid loss due to base neutralization and protected-sites-enhanced acid diffusion. Simplifying assumptions are made to derive analytical expressions for PEB. The model parameters are extracted from the following experiments. UV-visible spectroscopy is used to extract the resist absorbance parameters. The generation of acid is monitored using the method of 'base additions.' The extent of deprotection that occurs during the bake is determined by monitoring the characteristic FTIR absorbance band around 1170 cm-1 over a range of exposure doses and bake temperatures. Diffusion parameters are extracted from line end shortening (LES) measurements. These parameters are optimized using the Method of Feasible Directions algorithm. Application results show good agreement with experimental data for different LES features.
Influence of different functional groups on dissolution behavior of resist resins based on charge-transfer polymerization of cycloolefins with maleic anhydride was studied. tertButyl carboxylate moiety was used in all materials as an imaging group. Two approaches were identified for increase in the dissolution rate of totally deprotected polymers (Rmax). First, the Rmax value can be modified by changing the total amount of tertbutyl-protected and unprotected carboxylate moieties in the polymer. On the other hand, Rmax can be improved by introducing the base- hydrolyzable functionalities, such as a formate esters, into the polymer chain. It was established that such polymers are stable to hydrolysis in hydrophobic matrix but undergo quick hydrolysis in hydrophilic film. For example, a polymer in which the cycloolefin moiety has a formate side group displayed dissolution rate of approximately 10,000 angstrom/sec while an analogous polymer in which the cycloolefin moiety does not have a formate group showed a dissolution rate of approximately 500 angstrom/sec.
Through a series of statistical design experiments we optimized the lithographic performance of a 193 nm single layer resists based on a norbornene-maleic anhydride matrix resin. Several interesting findings were found including that having the PEB temperature improved the performance of the resist. The polymer composition was found to strongly influence the lithographic performance of the resist. Variables that we examined included acrylate loading and blocking level. By optimizing the composition of the polymer, we have obtained resist with high etch resistance, square profiles and 0.130 micron dense line ultimate resolution in 0.5 micron thick films. The resist formulations are compatible with industry standard 0.262 N TMAH. During exposure the resists does not suffer from the outgassing of volatile species.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.