Development of massively parallel electron beam direct write lithography using active-matrix nanocrystalline-silicon electron emitter arrays

Nanoscale lithographic technologies have been intensively studied for the development of the next generation of semiconductor manufacturing practices.While mask-less/direct-write electron beam(EB)lithography methods serve as a candidate for the upcoming 10-nm node approaches and beyond,it remains difficult to achieve an appropriate level of throughput.Several innovative features of the multiple EB system that involve the use of a thermionic source have been proposed.However,a blanking array mechanism is required for the individual control of multiple beamlets whereby each beamlet is deflected onto a blanking object or passed through an array.This paper reviews the recent developments of our application studies on the development of a high-speed massively parallel electron beam direct write(MPEBDW)lithography.The emitter array used in our study includes nanocrystalline-Si(nc-Si)ballistic electron emitters.Electrons are drifted via multiple tunnelling cascade transport and are emitted as hot electrons.The transport mechanism allows one to quickly turn electron beamlets on or off.The emitter array is a micro-electro-mechanical system(MEMS)that is hetero-integrated with a separately fabricated active-matrix-driving complementary metal-oxide semiconductor(CMOS)large-scale integration(LSI)system that controls each emitter individually.The basic function of the LSI was confirmed to receive external writing bitmap data and generate driving signals for turning beamlets on or off.Each emitted beamlet(10×10μm^(2))is converged to 10×10 nm^(2) on a target via the reduction electron optic system under development.This paper presents an overview of the system and characteristic evaluations of the nc-Si emitter array.We examine beamlets and their electron emission characteristics via a 1:1 exposure test.

Female mice exhibit both sexual and social partner preferences for vocalizing males

Acoustic signals are widely used as courtship signals in the animal kingdom.It has long been known that male mice emit ultrasonic vocalizations(USVs)in the presence of female mice or in response to female secretions.This observation led to the hypothesis that male USVs play a role in courtship behavior.Although previous studies showed that female mice have a social partner preference for vocalizing males,it is not known if they exhibit a sexual partner preference when given a choice.To address this issue,we examined the copulatory behaviors of female mice with either devocalized males(with or without the playback of the USVs)or sham-operated males in 2 different behavioral paradigms:the no-choice paradigm in the home cage of a male mouse(without choice of mating partners)or the mate-choice paradigm in a 3-chambered apparatus(with choice of mating partners).In the no-choice paradigm,female mice exhibited comparable sexual receptivity with sham-operated and devocalized males.In addition,we found that female mice showed more approach behavior to-wards devocalized males when male USVs were played back.In the mate-choice paradigm,female mice visited more frequently and stayed longer with sham-operated than devocalized males.Furthermore,we showed that female mice received more intromissions from sham-operated males than devocalized males.In summary,our results suggested that,although female mice can copulate equally with both devocalized and vocalizing males when given no choice of mating partner,female mice exhibit both sexual and social partner preferences for vocalizing males in the mate-choice paradigm.