Conventional Photolithography

Abstract Improvements in the contrast of e-beam exposed resists have been reported via the use of multiple interrupted development techniques. Additional baking is claimed to effect greater improvements in optical lithography. This so called intermediate development bake or (IDB) process, has recently been further simplified through adoption of a warm water treatment for the baking step. In the w arm w ater IDB process, the need to spin dry wafers is eliminated, thereby improving development throughput. We report on the application of all of these treatments to resists exposed using e-beam. Contrast curves obtained with multiple ww IDB processes at different temperatures and times are presented and compared with those obtained utilizing conventional development with varying PEB conditions. The effect on sizing both the top and base of the resist image as a function of exposure is also examined. Olin Hunt HEBR 214 has been at the focus of our work, although we additionally report on HEBR 242 and HPR 204, as well as Aspect System 912.

A simple method for the fabrication of nanogaps of less than 6 nm by conventional photolithography combined with patterned-size reduction technique is presented. The method is based on the complete conversion of a photolithographically embedded polysilicon structure on a silicon wafer into a semiconductor oxide layer and subsequent stripping of the oxide layer by etching with a buffer oxide etching (BOE) solution. With this technique, there are no principal limitations to fabricate nanostructures with different layouts and dimensions along with an improved pattern size resolution. The method is demonstrated by preparing self-aligned nanogaps of 5–6 nm dimensions on a Si–SiO2 substrate. Polysilicon material is used to fabricate the nanogap structure and gold is used for the electrodes. Two chrome masks are used to complete this work. The first one is for the nanogap pattern and the second one is for the pad electrode. The fabricated structure is optically and electrically
characterized with a field emission scanning electron microscope (FESEM) and dielectric analyzer (DA).

Abstract Use of a warm water soak midway during development results in improved resist profiles, particularly as a function of focus. Three positive resists are examined in order to qualitatively determine their particular time temperature response to such a process. We find that the expected trade off between temperature and time holds, furthermore there is no need to spin dry wafers during treatment. Control of the time and temperature gives rise to improved profiles relative to samples utilising interrupted development. The warm water IDB also requires lower overheads in development time, as well as being applicable to a wider range of Novolac/DNQ chemistries. The use of multiple warm water IDB treatments may be required in extending the focus latitude of both lines and contacts printed over topography.

A simple method for the fabrication of nanogaps of less than 6 nm by conventional photolithography combined with patterned-size reduction technique is presented. The method is based on the complete conversion of a photolithographically embedded polysilicon structure on a silicon wafer into a semiconductor oxide layer and subsequent stripping of the oxide layer by etching with a buffer oxide etching (BOE) solution. With this technique, there are no principal limitations to fabricate nanostructures with different layouts and dimensions along with an improved pattern size resolution. The method is demonstrated by preparing self-aligned nanogaps of 5-6 nm dimensions on a Si-SiO 2 substrate. Polysilicon material is used to fabricate the nanogap structure and gold is used for the electrodes. Two chrome masks are used to complete this work. The first one is for the nanogap pattern and the second one is for the pad electrode. The fabricated structure is optically and electrically characterized with a field emission scanning electron microscope (FESEM) and dielectric analyzer (DA).

209-212 209 Elsevier Improved Resist Contrast with Novolac based E-beam Resists using Modified Development Procedures. R. Jonckheere, N. Samarakone, L. Van den hove, and I. Daraktchiev* IMEC, Kapeldreef 75, B-3030, Leuven, Belgium *Olin Hunt NV, Europark-Noord 17-18, B-2700, St Niklaas, Belgium Improvements in the contrast of e-beam exposed resists have been reported via the use of multiple interrupted development techniques. Additional baking is claimed to effect greater improvements in optical lithography. This so called intermediate development bake or (IDB) process, has recently been further simplified through adoption of a warm water treatment for the baking step. In the w_arm water IDB process, the need to spin dry wafers is eliminated, thereby improving development throughput. We report on the application of all of these treatments to resists exposed using e-beam. Contrast curves obtained with multiple ww IDB processes at different temperatures and times are presented and compared with those obtained utilizing conventional development with varying PEB conditions. The effect on sizing both the top and base of the resist image as a function of exposure is also examined. Olin Hunt HEBR 214 has been at the focus of our work, although we additionally report on HEBR 242 and HPR 204, as well as Aspect System 912.

Use of a warm water soak midway during development results in improved resist profiles, particularly as a function of focus. Three positive resists are examined in order to qualitatively determine their particular time temperature response to such a process. We find that the expected trade off between temperature and time holds, furthermore there is no need to spin dry wafers during treatment. Control of the time and temperature gives rise to improved profiles relative to samples utilising interrupted development. The warm water IDB also requires lower overheads in development time, as well as being applicable to a wider range of Novolac/DNQ chemistries. The use of multiple warm water IDB treatments may be required in extending the focus latitude of both lines and contacts printed over topography.