Proximity effect (electron beam lithography)

About: Proximity effect (electron beam lithography) is a research topic. Over the lifetime, 940 publications have been published within this topic receiving 8508 citations.

Method of forming resist pattern

Abstract: PROBLEM TO BE SOLVED: To form a resist pattern of a desired design pattern, by considering, together with the proximity effect, pattern deviation from electron beam absorbing energy distribution which is generated in a developing process. SOLUTION: First, the speed of development and proximity effect parameters are measured (S1). Next, by using the measured development speed and values of proximity effect parameters, an electron beam absorbing energy distribution for obtaining resist pattern to be formed is obtained through calculation (S2). By substituting the coordinates of a pattern edge part into the electron beam absorbing energy distribution, a value Ep of electron beam absorbing energy in an edge part is calculated. A value Ea of electron beam absorbing energy at the pattern central position is obtained form the value Ep of electron beam absorbing energy in the edge part and the electron beam absorbing energy distribution. When the Ep and Ea are known, the electron beam exposure and an electron beam irradiated region which are used for obtaining target electron beam absorbing energy distribution can be obtained.

X‐ray mask fabrication using advanced optical lithography

Abstract: A viable method of x‐ray mask fabrication using advanced optical lithography is proposed and the results of a feasibility study using conventional optical lithography is presented. This method reduces the proximity effect compared to electron‐beam lithography for x‐ray masks. Thus, it achieves excellent critical dimension control and offers high productivity and low cost with a single layer resist process. This technology was applied to fabricating x‐ray masks with two 64 Mb dynamic random access memory (DRAM) circuit dies. The 64 Mb DRAM pattern on a five time reticle was replicated onto a 1‐μm‐thick positive resist coated on an extremely flat x‐ray mask substrate using a conventional i‐line stepper. The resist pattern was directly transferred to an x‐ray absorber Ta film using low‐wafer‐temperature electron cyclotron resonance plasma etching with SF6 gas. The resulting 0.75‐μm‐thick Ta pattern with vertical sidewalls was fabricated with 20 nm (3σ) critical dimension control. This simple process makes x‐ray masks with low defect density.

Direct-write X-ray lithography using a hard X-ray Fresnel zone plate.

Abstract: Results are reported of direct-write X-ray lithography using a hard X-ray beam focused by a Fresnel zone plate with an outermost zone width of 40 nm. An X-ray beam at 7.5 keV focused to a nano-spot was employed to write arbitrary patterns on a photoresist thin film with a resolution better than 25 nm. The resulting pattern dimension depended significantly on the kind of underlying substrate, which was attributed to the lateral spread of electrons generated during X-ray irradiation. The proximity effect originated from the diffuse scattering near the focus and electron blur was also observed, which led to an increase in pattern dimension. Since focusing hard X-rays to below a 10 nm spot is currently available, the direct-write hard X-ray lithography developed in this work has the potential to be a promising future lithographic method.

Forming method for resist pattern

Abstract: PURPOSE:To obtain the resist pattern in which a resist does not remain in an end edge by using two masks each regulating the longitudinal and lateral sizes of a rectangular pattern. CONSTITUTION:Cr patterns 14, 15 are formed onto a glass substrate 13, and the masks 11, 12 regulating the longitudinal and lateral size of the patterns are manufactured. The masks of the rectangular patterns are superposed, and mask patterns according to a predetermined design are obtained. When the resist is exposed by the masks of the rectangular patterns, the edges of the patterns are hardly exposed by a proximity effect because exposure regions and non-exposure regions are in contact at the angles of 180 deg. in designed pattern sections. Accordingly, the edge sections of designed patterns are not exposed even through exposure by the mask 12 in succession to the mask 11, and the resist patterns for forming minute connecting holes can be formed through development.