感应耦合等离子刻蚀InP工艺

采用Cl2/CH4/N2感应耦合等离子体对InP进行了刻蚀.系统地讨论了RF功率、ICP功率、反应腔压力、气体流量等工艺参数对InP材料端面刻蚀的影响.通过优化工艺参数,获得了光滑垂直的InP刻蚀端面,刻蚀速率达到841 nm/min,与SiO2的选择比达到15:1.     

ICP刻蚀4H-SiC栅槽工艺研究

为避免金属掩膜易引起的微掩膜,本文采用SiO2介质作为掩膜,SF6/O2/Ar作为刻蚀气体,利用感应耦合等离子体刻蚀(ICP)技术对4H-SiC trench MOSFET栅槽刻蚀工艺进行了研究。本文详细研究了ICP刻蚀的不同工艺参数对刻蚀速率、刻蚀选择比以及刻蚀形貌的影响。实验结果表明:SiC刻蚀速率随着ICP功率和RF偏压功率的增大而增加;随着气体压强的增大刻蚀选择比降低;而随着氧气含量的提高,不仅刻蚀选择比增大,而且能够有效地消除微沟槽效应。刻蚀栅槽形貌和表面粗糙度分别通过扫描电子显微镜和原子力显微镜进行表征,获得了优化的栅槽结构,RMS表面粗糙度0.4nm。     

Cl2/Ar感应耦合等离子体刻蚀InP工艺研究

采用Cl2／Ar感应耦合等离子体对InP进行了刻蚀。讨论了直流自偏压、ICP功率、气体总流量和气体组分等因素对刻蚀速率和粗糙度的影响。结果表明Cl2／Ar气体组分是决定刻蚀效果的重要因素。当Cl2含量为30％左右时,刻蚀中的物理溅射与化学反应过程趋于平衡,刻蚀速率处于峰值区,同时刻蚀粗糙度也可达到最小值。SEM照片显示刻蚀表面光洁。侧壁陡直。     

ICP干法刻蚀GaAs背孔工艺研究

采用金属Ni作为掩膜,Cl2/BCl3作为刻蚀气体,利用感应耦合等离子体刻蚀(ICP)技术对Ga As HEMT背孔工艺进行研究。本文详细研究了ICP功率、反应室压强、Cl2/BCl3流量比以及RF功率对刻蚀速率、刻蚀形貌以及"长草"效应的影响。实验结果表明:刻蚀速率随ICP功率、Cl2/BCl3流量、RF功率的增加而增加,但随反应室压强的增加,刻蚀速率先增加后降低;相同RF功率条件下,背孔陡直性受ICP功率、反应室压强以及刻蚀气体流量比的影响十分明显;而RF功率则对背孔"长草"效应有较大影响。通过优化刻蚀条件,在ICP功率为500 W,反应室压强为0.4 Pa,Cl2/BCl3流量为20/5 m L/min,RF功率为120 W的刻蚀条件下,刻蚀背孔陡直性好,侧壁平滑,底部平整,刻蚀速率达到3μm/min。     

薄膜体声波滤波器AlN压电薄膜的ICP刻蚀研究

随着5G通信技术的发展,通信频段不断提高,以氮化铝(AlN)为压电薄膜材料的薄膜体声波滤波器作为目前唯一可集成的射频前段滤波器成为研究热点之一。本文开展AlN材料刻蚀工艺的实验研究,实验中采用光刻胶作为刻蚀掩膜,Cl_2/BCl_3作为刻蚀工艺气体,通过一系列工艺影响参数调整及相应刻蚀结果分析,获得了ICP源功率、RF偏压功率、腔体压强和BCl_3气体流量对AlN材料和光刻胶掩膜刻蚀速率、刻蚀形貌的影响规律。通过综合优化工艺参数,最终得到了侧壁平坦、表面光滑的空气隙型薄膜体声波滤波器三明治结构。     

C_(4)F_(6)/SF_(6)混合气体对硅基材料的ICP刻蚀工艺研究北大核心CSCD

为避免深硅刻蚀工艺所引起的扇贝纹效应,同时减少其工艺气体所带来的温室效应,本文将新一代环保电子刻蚀气C4F6引入硅刻蚀工艺,采用刻蚀与钝化同步进行的伪Bosch工艺刻蚀硅槽孔。研究了ICP功率、RIE功率、腔体压强和C_(4)F_(6)/SF_(6)气体流量比对刻蚀速率、光刻胶/硅刻蚀选择比及刻蚀形貌的影响。结果表明,一定程度增加ICP功率和RIE功率可分别提高等离子体密度和物理轰击刻蚀作用;腔体压强对粒子平均自由径有较大影响;而C4F6流量的增加可加强刻蚀侧壁保护机制。通过综合优化工艺参数,获得了2.8μm/min硅刻蚀速率,3.1的光刻胶/硅刻蚀选择比和侧壁平坦,表面光滑,垂直度高的刻蚀形貌。     

薄膜体声波滤波器AlN压电薄膜的ICP刻蚀研究北大核心CSCD

随着5G通信技术的发展,通信频段不断提高,以氮化铝(AlN)为压电薄膜材料的薄膜体声波滤波器作为目前唯一可集成的射频前段滤波器成为研究热点之一。本文开展AlN材料刻蚀工艺的实验研究,实验中采用光刻胶作为刻蚀掩膜,Cl2/BCl3作为刻蚀工艺气体,通过一系列工艺影响参数调整及相应刻蚀结果分析,获得了ICP源功率、RF偏压功率、腔体压强和BCl3气体流量对AlN材料和光刻胶掩膜刻蚀速率、刻蚀形貌的影响规律。通过综合优化工艺参数,最终得到了侧壁平坦、表面光滑的空气隙型薄膜体声波滤波器三明治结构。     

基于CF_4/Ar高密度感应耦合等离子体的BZN薄膜的刻蚀工艺研究

使用CF4/Ar高密度感应耦合等离子体(ICP)对磁控溅射法制得的铌酸锌铋(BZN)薄膜进行了干法刻蚀工艺研究。分析了BZN薄膜的刻蚀速率随工艺气体流量比、总流量和工作压强的改变而出现极大值的原因,展示了BZN薄膜的刻蚀速率随ICP功率的增大而线性增加的趋势。研究结果表明,使用CF4/Ar感应耦合等离子体对BZN薄膜进行刻蚀的机理为物理辅助的化学反应刻蚀。BZN薄膜的最佳刻蚀工艺参数为CF4/Ar流量比3/2、总流量25sccm、工作压强1.33Pa、ICP功率800W,使用此参数对BZN薄膜进行刻蚀,最大刻蚀速率为26nm/min,刻蚀后薄膜边缘齐整、表面光滑、形状完整。     

ICP深硅刻蚀工艺研究

感应耦合等离子体(ICP)刻蚀技术是微机电系统器件加工中的关键技术之一.利用英国STS公司STS Multiplex刻蚀机,研究了ICP刻蚀中极板功率、腔室压力、刻蚀/钝化周期、气体流量等工艺参数对刻蚀形貌的影响,分析了刻蚀速率和侧壁垂直度的影响原因,给出了深硅刻蚀、侧壁光滑陡直刻蚀和高深宽比刻蚀等不同形貌刻蚀的优化工艺参数.     

InAs/GaSb超晶格红外探测器台面的ICP刻蚀研究

采用分子束外延方法在GaSb衬底上生长InAs/GaSb超晶格红外薄膜材料,为获得台面结构,采用电感耦合等离子体(ICP)刻蚀技术和Cl2/Ar刻蚀气体,分别研究了不同刻蚀时间、不同气体比例及不同功率对GaSb、InAs及InAs/GaSb超晶格刻蚀速率和刻蚀形貌的影响。结果表明,由于刻蚀产物InCl x的低挥发性阻挡了Cl2的刻蚀,InAs的刻蚀速率低于GaSb;Cl2比例在20%~40%时,刻蚀表面粗糙度最小,明显低于湿法腐蚀造成的表面损伤,有助于形成良好的欧姆接触和减小器件的表面漏电流。     

AlGaN/GaN HEMT栅槽低损伤刻蚀技术

对AlGaN/GaN HEMT栅槽低损伤刻蚀技术进行研究,通过加入小流量的具有钝化缓冲作用的C2H4,对Cl2/Ar/C2H4的工艺条件进行了优化,有效地降低了栅槽刻蚀造成的AlGaN表面损伤和器件退化,同时防止反应生成物淀积在栅槽表面,改善了肖特基结特性,提高了栅极调控能力,实现凹栅槽的低损伤刻蚀.     

基于ICP的金属钛深刻蚀

MEMS应用领域的扩展要求开发硅材料之外其他新型材料的三维微细加工技术．为此,对金属钛这一新型MEMS体材料的三维加工进行了探索．金属钛不仅延展性和导电性好,且断裂韧度高、高低温特性以及生物兼容性好．采用电感耦合等离子体源（inductively coupled plasma,ICP）技术对金属钛进行三维深刻蚀,采用不同刻蚀掩模、氯基刻蚀气体,研究了线圈功率、平板功率和Cl2流量对刻蚀速率和选择比等工艺参数的影响,并对Ti深刻蚀参数进行了优化,得到0．91μm/min的刻蚀速率,可实现光滑表面和陡直侧壁．     

Material-selective etching of InP and an InGaAsP alloy

Wet chemical etchants are inexpensive and can be employed easily in device fabrication. Material-selective etchants extend the design flexibility for devices with heterostructures. Several etchants on (100) InP and LPE-grown (100) InGaAsP are studied with emphasis on smooth crystal surfaces and well-defined mesa-structures by use of photoresist. The best results are obtained with the system glycerine: HCl HClO₄ for preferential attack of InP and with the system H₂O H₂SO₄ H₂O₂ for preferential etching of InGaAsP. Detailed information is given on the etching solutions investigated, on the etching conditions and the etching rates of the most useful etchants.     

InAs0.45P0.55/InP strained multiple quantum wells intermixed by inductively coupled plasma etching

The intermixing effect on InAs_0.45P_0.55/InP strained multiple quantum wells (SMQWs) by inductively coupled plasma (ICP) etching and rapid thermal annealing (RTA) is investigated. Experiments show that the process of ICP etching followed RTA induces the blue shift of low temperature photoluminescence (PL) peaks of QWs. With increasing etching depth, the PL intensities are firstly enhanced and then diminished. This phenomenon is attributed to the variation of surface roughness and microstructure transformation inside the QW structure during ICP processing.     

Leakage Current Analysis of Nitride-Based Photodetectors by Emission Microscopy Inspection

Leakage properties of nitride-based photodetectors (PDs) subjected to inductively coupled plasma (ICP) etching has been investigated by using emission microscopy inspection (EMMI). ICP etching would cause significant damage to GaN metal-semiconductor-metal (MSM) PDs. The damage was proven to induce leakage current via the conductive surface of the device by using emission microscopy inspection. However, the surface damage of MSM PDs could be partially recovered by E-beam SiO₂ passivation. As for the passivation for p-i-n photodetectors, the effect was not significant in the reduction of dark current due to smaller etched area as compared to the whole area of p-i-n PDs. The leakage current path analysis of p-i-n PDs by EMMI technique had also been investigated. Finally, the plasma enhanced chemical vapor deposition (PECVD) SiO₂ passivation was proven to be a potential process to improve the reliability of p-i-n PDs.     

Fabrication of SiO2 Microcantilever Using Isotropic Etching With ICP

This paper reports a new design and microfabrication process for high sensing guard-armed silicon dioxide (SiO₂ ) microcantilever sensor, which can be widely used in chemical, environmental and biomedical applications. One sensor platform consists of two SiO₂ cantilever beams as the sensing and reference elements, two connecting wings, and three guard arms. The guard arms prevent damage to the cantilever beam from collision. To efficiently release the SiO₂ cantilevers from the silicon substrate, an isotropic etch method using inductively coupled plasma (ICP) was developed. The isotropic etching with ICP system provides an advantage in good profile control and high etching rate than wet isotropic etching or conventional RIE (reactive ion etching); however, it has not been gained many attentions. In this work, the effects of chamber pressure, plasma source power, substrate power, SF₆ flow rate relating with Si etching rate, undercutting rate, and isotropic ratio were investigated and discussed. The optimum isotropic etching process achieved a 9.1 mum/min etch rate, 70% isotropic ratio, and 92% etching uniformity. The SiO₂ cantilever sensor was fabricated and the cantilever beam was successfully released using a patterned photoresist layer as an etching mask. This plasma isotropic etching release processing can be also applied to release other SiO₂ or metal suspended MEMS structures, such as bridges and membranes, with a fast etch rate and reasonable isotropic ratio.     

A high-coverage nanoparticle monolayer for the fabrication of a subwavelength structure on InP substrates

Subwavelength structures (SWSs) were fabricated on the Indium Phosphide (InP) substrate by utilizing the confined convective self-assembly (CCSA) method followed by reactive ion etching (RIE). The surface condition of the InP substrate was changed by depositing a 30-nm-thick SiO2 layer and subsequently treating the surface with O2 plasma to achieve better surface coverage. The surface coverage of nanoparticle monolayer reached 90% by using O2 plasma-treated SiO2/InP substrate among three kinds of starting substrates such as the bare InP, SiO2/InP and O2 plasma-treated SiO2/InP substrate. A nanoparticle monolayer consisting of polystyrene spheres with diameter of 300 nm was used as an etch mask for transferring a two-dimensional periodic pattern onto the InP substrate. The fabricated conical SWS with an aspect ratio of 1.25 on the O2 plasma-treated SiO2/InP substrate exhibited the lowest reflectance. The average reflectance of the conical SWS was 5.84% in a spectral range between 200 and 900 nm under the normal incident angle.     

Antireflective hydrophobic si subwavelength structures using thermally dewetted Ni/SiO2 nanomask patterns

We report the disordered silicon (Si) subwavelength structures (SWSs), which are fabricated with the use of inductively coupled plasma (ICP) etching in SiCl4 gas using nickel/silicon dioxide (Ni/SiO2) nanopattens as the etch mask, on Si substrates by varying the etching parameters for broadband antireflective and self-cleaning surfaces. For the fabricated Si SWSs, the antireflection characteristics are experimentally investigated and a theoretical analysis is made based on the rigorous coupled-wave analysis method. The desirable dot-like Ni nanoparticles on SiO2/Si substrates are formed by the thermal dewetting process of Ni films at 900 degrees C. The truncated cone shaped Si SWS with a high average height of 790 +/- 23 nm, which is fabricated by ICP etching with 5 sccm SiCl4 at 50 W RF power with additional 200 W ICP power under 10 mTorr process pressure, exhibits a low average reflectance of approximately 5% over a wide wavelength range of 450-1050 nm. The water contact angle of 110 degrees is obtained, indicating a hydrophobic surface. The calculated reflectance results are also reasonably consistent with the experimental data.     

Comparison of dry etching of PMMA and polycarbonate in diffusion pump-based O2 capacitively coupled plasma and inductively coupled plasma

We report a comparison of dry etching of polymethyl methacrylate (PMMA) and polycarbonate (PC) in O₂ capacitively coupled plasma (CCP) and inductively coupled plasma (ICP). A diffusion pump was used as high vacuum pump in both cases. Experimental variables were process pressure (30-180 mTorr), CCP power (25-150 W) and ICP power (0-350 W). Gas flow rate was fixed at 5 sccm. An optimized process pressure range of 40-60 mTorr was found for the maximum etch rate of PMMA and PC in both CCP and ICP etch modes. ICP etching produced the highest etch rate of 0.9 μm/min for PMMA at 40 mTorr, 100 W CCP and 300 W ICP power, while 100 W CCP only plasma produced 0.46 μm/min for PMMA at the same condition. For polycarbonate, the highest etch rates were 0.45 and 0.27 μm/min, respectively. RMS surface roughnesses of PMMA and PC were about 2-3 nm after etching. Etch selectivity of PMMA over photoresist was 1-2 and that of PC was less than 1. When ICP power increased from 0 to 350 W, etch rates of PMMA and PC increased linearly from 0.47 to 1.18 μm/min and from 0.18 to 0.6 μm/min, while the negative self bias slightly reduced from 364 to 352 V. Increase of CCP power raised both self bias and PMMA etch rate. PMMA etch rates were about 3 times higher than those of PC at the same CCP conditions. SEM data showed that there was some undercutting of PMMA and PC after etching at 300 W ICP, 100 W CCP and 40 mTorr. The results also showed that the etched surface of PMMA was rough and that of PC was relatively smooth.