纳米压印中残余胶刻蚀工艺研究

压印光刻在图形转移之后,需要去除残留在凹槽底部的胶。采用RIE工艺对紫外压印胶的刻蚀速率进行了研究。结果表明,随着气压或气体流量增大,刻蚀速率均会先增加,达到一定值后又开始下降;在刻蚀气体中加入SF_6后,会减少钻蚀,但刻蚀速率会有少许下降;而在刻蚀气体中加入少量SF_6且压强及流量较大时,各部分的刻蚀速率一致性较好。由此得到了一个优化后的刻蚀条件,反应气体:O_2+SF_6,气体流量分别为40 cm~3/min和5 cm~3/min,压强9.31 Pa,RF功率20 W,此时刻胶速率可稳定在0.8μm/min左右,且均匀性较好。     

纳米压印模板需要高质量的检测技术

纳米压印光刻经学术和行业团体近十年的研究之后，已逐渐开始对半导体行业产生引导作用。简单地讲，纳米压印是把一个1×的模板压进一个柔性层，从而在衬底上制作图形。斯坦福大学的电子工程教授Fabian Pease说：“它引人注意之处是具有半导体行业现在非常感兴趣的分辨率，即远低于100nm的线条，而在这个范围内，如果无法用纳米压印光刻来实现，光学光刻将变得很昂贵。”     

紫外压印模版的制备

概述了紫外压印的原理及其优点,并通过对紫外压印模版特殊性的分析,提出了两种紫外压印模版的制作。用反应离子刻蚀法制作了玻璃模版,用浇灌法制作了聚二甲基硅氧烷(PDMS)模版,最后给出了实验过程和结果。实验表明,用反应离子刻蚀法可以制作出具有100 nm特征尺寸、图形的深度为50 nm的玻璃模版,而且通过控制刻蚀时间可以得到需要的图形深度。用浇灌法可以制作出具有100 nm特征尺寸、图形深度为145 nm的聚合物模版。     

纳米压印工艺中关键技术

纳米压印技术由于其分辨率高、工艺成本低以及适于大规模工业化生产的优点被广泛利用于纳米尺度的半导体器件的制作之中。然而,传统的硬模板压印技术存在着模板寿命短、大面积均匀性差以及易受颗粒影响的缺点。本文提出了一种高分子聚合物软模板（IPS）压印的方法来改进以上缺点,同时,本文提出在软模板制作和后续的紫外压印中采用变温变压阶梯升降压的方法来提高压印过程中胶的流动性,以提高压印图形的质量。最后,我们利用这种方法方法出了高质量的50纳米线宽的光栅图形。     

硅油稀释PDMS法制备紫外纳米压印软模板

软模板的制作是紫外纳米压印中关键的技术,模版的分辨率直接决定了压印图形的最小分辨率。使用具有高度均匀、100nm级孔洞阵列结构的多孔氧化铝作为母版,使用基于液态浇铸的硅油稀释聚二甲基硅氧烷(硅油和聚二甲基硅氧烷的质量比为1:2)法制备出具有规则点阵结构的软模板。通过SEM和AFM表征发现,特征图形得到了有效转移,特征尺度保持在100nm左右。相对于传统的模板制备方法,此方法成本低、流程简单、适合大规模生产,是一种非常有前途的软模板制备方法。     

纳米压印技术的研究进展

纳米压印技术由于具有操作简单、高分辨率、成本低、重复性高等优点,近年来受到国内外研究机构的高度重视.本文主要介绍了目前主流的几种纳米压印技术,并简要概述了纳米压印技术的研究现状和应用前景.     

纳米压印用压印胶的研究进展

纳米压印需采用压印胶进行图案转移,作为压印技术的关键材料,压印胶的性能直接影响到纳米压印的质量。根据压印技术的工艺特点对压印胶进行了分类,介绍了纳米压印用热压印胶和紫外压印胶的发展研究现状和性能优缺点,分析了目前压印胶存在的主要问题,并指出压印胶的研究主要是提高压印胶的脱模性能、固化速率以及简化工艺,主要列举了含氟硅类压印胶、双表面能压印胶的性能特点,并展望了未来的发展方向。     

纳米压印光刻技术--下一代批量生产的光刻技术

纳米压印光刻技术已被证实是纳米尺寸大面积结构复制的最有前途的下一代技术之一。这种速度快、成本低的方法成为生物化学、μ级流化学、μ-TAS和通信器件制造以及纳米尺寸范围内广泛应用的一种日渐重要的方法,如生物医学、纳米流体学、纳米光学应用、数据存储等领域。由于标准光刻系统的波长限制、巨大的开发工作量、以及高昂的工艺和设备成本,纳米压印光刻技术可能成为主流IC产业中一种真正富有竞争性方法。对细小到亚10nm范围内的极小复制结构,纳米压印技术没有物理极限。从几种纳米压印光刻技术中选择两种前景广阔的方法——热压印光刻(HEL)和紫外压印光刻(UV-NIL)技术给予介绍。两种技术对各种各样的材料以及全部作图的衬底大批量生产提供了快速印制。重点介绍了HEL和UV-NIL两种技术的结果。全片压印尺寸达200mm直径,图形分辨力高,拓展到纳米尺寸范围。     

纳米压印光刻在CMOS HDD中的快速发展

据Molecular Imprints公司的首席执行官Mark Melliar-Smith所言,纳米压印技术明年将稳步跨入硬盘制造舞台,在几年之后达到CMOS高密度存储器工艺的极限。Molecular Imprints公司是一家压印工具的开发商和制造商。     

紫外纳米压印技术的图形转移层工艺研究

研究了紫外纳米压印技术的图形转移层工艺,通过改变膜厚进行压印对比实验,将转速控制在3000～4000r/min,成功地得到了50nm光栅结构的高保真图形,复型精度可以达到93.75%。同时阐明,纳米压印技术由于具有超高分辨率、低成本、高产量等显著特点,将成为下一代光刻技术(NGL)的主要候选者之一。     

Fast patterning and dry-etch of SiNχ for high resolution nanoimprint templates

We developed a simplified nanofabrication process for imprint templates by fast speed electron beam lithography (EBL) and a dry etch technique on a SiNx substrate, intended for large area manufacturing. To this end,the highly sensitive chemically amplified resist (CAR), NEB-22, with negative tone was used. The EBL process first defines the template pattern in NEB-22, which is then directly used as an etching mask in the subsequent reactive ion etching (RIE) on the SiNx to form the desired templates. The properties of both e-beam lithography and dry etch of NEB-22 were carefully studied, indicating significant advantages of this process with some drawbacks compared to when Cr was used as an etching mask. Nevertheless, our results open up a good opportunity to fabricate high resolution imprint templates with the prospect of wafer scale manufacturing.     

Replication of high ordered nano-sphere array by nanoimprint lithography

High ordered nano-sphere array patterns on Si substrate were fabricated using nanoimprint lithography. First, using hot embossing method, poly vinyl chloride (PVC) based polymer replica template was duplicated from original high ordered nano-sphere array patterns, which was fabricated by evaporation method. The monolayer transferring condition can be achieved by varying hot embossing pressure. Then, through UV nanoimprint lithography with the replicated polymer template, imprinted patterns, which has high ordered nano-sphere array patterns, was successfully fabricated on Si and flexible PET substrate.     

Impact of molecular weight of polymers and shear rate effects for nanoimprint lithography

Linear polystyrene of different weight averaged molecular weight (M_w = 58 kg/mol and 353 kg/mol) and a narrow molecular weight distribution was imprinted to point out differences in the flow behaviour caused by the polymer’s molecular weight in a typical hot embossing/thermal nanoimprint process. Residual layer thickness and uniformity as well as defects were taken as a measure to qualify the imprint process. Since polymer viscosity is addressed as the main material parameter, a full thermo-mechanical characterisation of the two polymers via parallel plate dynamic viscosimetry was performed prior to imprint. The main process parameter responsible for viscosity, the temperature, was varied from about 30 to 150 K above the glass transition. In addition the amount of polymer supplied for the process was varied, i.e. the initial spin-coated polymer layer thickness. Situations representing ‘underfilling’, ‘filling’ and ‘overfilling’ of the stamp cavities in specific regions were investigated. Squeezed flow simulations were performed taking into account the increase of pattern size and the filling of cavities during the ongoing imprint, which have substantial impact on the residual layers obtained. The results show that shear thinning is an issue in a high pressure hot embossing system. It governs the initial phase of the imprint featuring a rapid decrease of the polymer height. From theoretical considerations, a model could be derived for the imprint procedure under shear thinning in a constant pressure system which was able to interpret the observed phenomena. Despite the macroscopic nature of the thermo-mechanical analysis, the standard viscosimetric data for the polymers appeared to be sufficient to understand the experimental results.     

Characterization of adhesion property between fused silica and thermoplastic polymer film in thermal nanoimprint lithography using a novel pull-off test

A novel pull-off test that mimics the actual thermal NIL process was conducted to investigate the adhesion properties between a flat fused silica and thermoplastic polymer film used in thermal NIL process. The pull-off force was measured under various NIL conditions—such as use of various polymer materials, imprint pressures, and separation velocities—and the surfaces of the mold and polymer film were observed after the test. The anti-sticking layer (ASL) derived from (1H,1H,2H,2H-perfluorooctyl)trichlorosilane (F₁₃-OTS) was coated on the fused silica and its effects on the adhesion characteristics was also examined. In cases of the mold without ASL, the pull-off force varied significantly according to the process conditions and damage on the polymer film was observed in most of the tests. In cases of the mold coated with the ASL, on the other hands, the pull-off force was maintained at a lower level in the range of the imprint pressure from 2 to 10 MPa or separation velocity from 1 to 25 μm/s, and there was no damage to the polymer film due to adhesion.     

Optimization and experimentation of nanoimprint lithography based on FIB fabricated stamp

The maskless and resistless focused ion beam (FIB) fabrication approach to make imprint stamp is straightforward and rapid compared to the traditional electron beam method. FIB etched stamp consisting of grooves was employed to nanoimprint polymer mr-I 9020. Taguchi orthogonal experiment with four parameter elements, one at three levels was used to optimize the experiment parameters by the analysis of means and variances. The most significant factor influencing the height of replicated lines is imprint temperature and the optimal combination of the process parameters are the imprint temperature at 160 °C, imprint force at 1200 N, loading force velocity at 0.2 mm/min, and imprint time at 300 s.     

Fabrication and application of metallic nano-cantilevers

A new approach was developed in this work to fabricate metallic nano-cantilevers using a one-mask process and a deep reactive ion etch (DRIE) technique. 40-nm-thick Al and 70-nm-thick Au cantilevers of lengths from 5 μm and widths in the range of 200-300 nm were fabricated on a silicon substrate. The silicon underneath the suspended beams was completely etched. Short Al nano-cantilevers were used to find local residual stress induced in rapid thermal oxidation and the oxidized spots according to the deflection profiles of the nano-cantilevers. The deflection profiles were determined with the aid of a scanning electron microscope (SEM). Compared with a single feedback in the existing cantilever-based static methods, i.e., the deflection of the open end of a cantilever, the whole deflection profile provides more information regarding the effect of surface stresses on a cantilever.     

GaAs、AlAs、DBR反应离子刻蚀速率的研究

采用 BCl3和 Ar作为刻蚀气体对 Ga As、Al As、DBR反应离子刻蚀的速率进行了研究 ,通过控制反应的压强、功率、气体流量和气体组分达到对刻蚀速率的控制 .实验结果表明 :在同样条件下 Ga As刻蚀的速率高于 DBR和 Al As,在一定条件下 Ga As刻蚀的刻蚀速率可达 40 0 nm/m in,Al As的刻蚀速率可达 35 0 nm/min,DBR的刻蚀速率可达 340 nm/min,刻蚀后能够具有光滑的形貌 ,同时能够形成陡直的侧墙 ,侧墙的角度可达 85°.     

新型含硅丙烯酸酯型纳米压印胶的研究与应用

纳米压印技术因其成本低、产量高的优点广受关注,而开发可适用于纳米压印的压印胶成为该工艺的关键。合成了一种硅含量高的单体三(三甲基硅氧基)甲基丙烯酰氧丙基硅烷(TRIS),制备了一种新型紫外纳米压印用含硅丙烯酸酯型压印胶,用四点弯曲实验机和接触角测试仪表征了压印胶与模板的黏附性能,研究了配方组成对模板黏附性能的影响,优化得到了抗黏附性能优异的配方。压印实验结果表明,该压印胶与模板分离时无粘连。AFM与SEM测试结果表明,压印胶上复制得到了线宽149 nm、周期298 nm、深宽比为1的纳米光栅图形,图形结构完整。     

Fabrication of carbon nanotube arrays for field emission and sensor devices by nanoimprint lithography

This work brings forth the idea of incorporating insulation in the resist used for ultraviolet (UV) curing nanoimprint lithography (NIL). Carbon nanotubes (CNTs) are grown in the space between two insulated resist patterns on the conductive substrate to make CNTs arrays. Two imprinting processes, soft UV curing NIL with DRPPR process and novel NIL without cured residual resist, are presented to achieve the insulation patterns. First the fabricating process is performed using a polydimethylsiloxane (PDMS) stamp. Subsequently, inductively coupled plasma (ICP) is essential to wipe off the residual resist film. To avoid the ICP process, a novel UV curing NIL is presented. Its special hard quartz stamp with chrome shelter can protect the residual resist film out of curing during the UV exposure process, and the uncured resist can be easily removed by ultrasonic vibration in organic solutions. The CNT arrays are prepared on the patterned substrates by the pyrolysis of iron phthalocyanine (FePc). Field emission experiments reveal that the turn-on field of those CNTs arrays is low to 1.3 V/um.     

基于SEM纳米级电子束曝光机的快速束闸设计

基于扫描电镜(SEM)的纳米级电子束曝光系统能够以较低成本满足科研单位对纳米加工设备的需求。在电子束曝光系统中,需要快速束闸控制电子束通断以实现纳米图像的多场曝光。从安装位置、机械结构和驱动器等方面讨论快速束闸的设计。