基于BCl3感应耦合等离子体的蓝宝石光滑表面刻蚀

利用Ar/BCl3、Cl2/BCl3和SF6/BCl3感应耦合等离子体(ICP),研究了蓝宝石(Al2O3)材料的干法刻蚀特性.实验表明,优化BCl3含量(80%),可以提高对Al2O3衬底的刻蚀速率;在BCl3刻蚀气体中加入20%的Ar气可以在高刻蚀速率下同时获得优于未刻蚀Al2O3衬底表面的光滑刻蚀表面和较好的刻蚀侧壁,原子力显微镜(AFM)分析得到最优刻蚀平整度为0.039 nm,俄歇电子能谱(AES)分析其归一化Al/O原子比为0.94.     

相变材料等离子体刻蚀的研究进展

首先综述了相变材料等离子体刻蚀技术的研究进展,然后讨论了影响相变材料等离子体刻蚀的主要工艺参数,如线圈功率、腔体气压、偏压、刻蚀气体及气体比例等,进而解释了工艺参数与刻蚀结果的依赖关系。同时采用多种分析手段,对相变材料在等离子体刻蚀工艺中产生的刻蚀损伤进行了分类和表征,并基于该分析结果提出了工艺优化方案。最后总结了相变材料等离子体刻蚀技术的反应机理,相变材料的刻蚀是自发反应与离子辅助化学反应相结合的过程,同时物理溅射与低挥发性产物的离子激发脱附也起着重要的辅助作用。     

Cl2/Ar感应耦合等离子体刻蚀Si工艺研究

采用Cl2/Ar感应耦合等离子体（ICP）对单晶硅进行了刻蚀,工艺中用光刻胶作掩膜。研究了气体组分、ICP功率和RF功率等工艺参数对硅刻蚀速率和硅与光刻胶刻蚀选择比的影响,同时还研究了不同工艺条件对侧壁形貌的影响。结果表明,由于物理刻蚀机制和化学刻蚀机制的相对强度受到混合气体中Cl2和Ar比例的影响,硅刻蚀速率随着Ar组分的增加而降低,同时选择比也随之降低。硅刻蚀速率随着ICP功率的增大先增大继而减小,选择比则成上升趋势。硅刻蚀速率和选择比均随RF功率的增大单调增大。在Cl2/Ar混合气体的刻蚀过程中,离子辅助溅射是决定硅刻蚀效果的重要因素。同时,文中还研究分析了刻蚀工艺对于微槽效应和刻蚀侧壁形貌的影响,结果表明,通过提高ICP功率可以有效减小微槽和平滑侧壁。进一步研究了SiO2掩膜下,压强改变对于硅刻蚀形貌的影响,发现通过降低压强,可以明显地抑制杂草的产生。     

NH3等离子体钝化对Al2O3/SiGe界面的影响

研究了不同条件的非原位NH_3等离子体钝化对Al_2O_3/SiGe/Si结构界面组分的影响。在p型Si(100)衬底上外延一层30 nm厚的应变Si_0.7Ge_0.3,采用双层Al_2O_3结构,第一层1 nm厚的Al_2O_3薄膜为保护层,之后使用非原位NH_3等离子体分别在300和400℃下对Al_2O_3/SiGe界面进行不同时间和功率的钝化处理,形成硅氮化物(SiN_xO_y)和锗氮化物(GeN_xO_y)的界面层。通过X射线光电子能谱(XPS)分析表面的物质成分,结果表明NH_3等离子体钝化在界面处存在选择性氮化,更倾向于与Si结合从而抑制Ge形成高价态,这种选择性会随着时间的增加、功率的增高和温度的升高变得更加明显。     

利用CH4/H2/Ar及Cl2高密度等离子体对InSb的高速率刻蚀研究（英文）

利用感应耦合等离子体(ICP)进行了InSb刻蚀研究。为了实现高的刻蚀速率同时保证光滑的刻蚀表面,研究中在CH4/H2/Ar气氛中引入了Cl2。研究发现,对InSb的刻蚀速率随Cl2含量及ICP功率的升高而线性增加。当Cl2含量增加到超过12%或ICP功率大于900 W时,刻蚀表面变得粗糙,而易引起刻蚀损伤的直流偏压随ICP功率的升高而降低。此现象归因于刻蚀副产物InCl3在样品表面的聚集进而妨碍均匀刻蚀反应所致。当样品温度从20℃提高到120℃,刻蚀速率及表面粗糙度无明显变化。通过试验研究,实现了对InSb的高速率、高垂直度刻蚀,刻蚀速率大于500 nm/min,对SiO2掩模刻蚀选择比大于6,刻蚀表面光洁,刻蚀垂直度可达80°。     

NH3流量调控Ⅴ/Ⅲ比对HVPE生长GaN薄膜的影响

氢化物气相外延(HVPE)法具有生长成本低、生长条件温和、生长速率快等优点,被认为是生长高质量GaN单晶衬底的最有潜力的方法。为了优化HVPE生长GaN的条件,通过改变NH3流量调控Ⅴ/Ⅲ比(NH3流量与HCl流量之比)。通过建立简单的生长模型,对不同Ⅴ/Ⅲ比下GaN薄膜形态变化的机理进行了分析,研究了HVPE生长过程中氮源(Ⅴ族)和镓源(Ⅲ族)不同流量比对结晶质量和表面形貌的影响。实验结果表明,低Ⅴ/Ⅲ比会导致成核密度低,岛状晶胞难以合并;高Ⅴ/Ⅲ比会降低表面Ga原子的迁移率,导致表面高度差异大,结晶质量差。与Ⅴ/Ⅲ比为15.000和28.125相比,Ⅴ/Ⅲ比为21.250时更适合GaN薄膜生长,得到的晶体质量最高。     

阳极刻蚀提升Ga2O3肖特基势垒二极管击穿特性

提出了一种采用阳极刻蚀提升Ga₂O₃肖特基势垒二极管(SBD)击穿特性的新方法。基于氢化物气相外延(HVPE)法生长的Ga₂O₃材料制备了Ga₂O₃纵向SBD。在完成阳极制备后,对阳极以外的Ga₂O₃漂移区进行了不同深度的刻蚀,刻蚀完成后,在器件表面生长了SiO₂介质层,随后制备了场板结构。测试结果显示,刻蚀后器件的比导通电阻小幅上升,而反向击穿电压均大幅提升。刻蚀深度为300 nm的β-Ga₂O₃ SBD具有最优特性,其比导通电阻(R_{on, sp})为2.5 mΩ·cm²,击穿电压(V_br)为1 410 V,功率品质因子(FOM)为795 MW/cm²。该研究为高性能Ga₂O₃ SBD的制备提供了一种新方法。     

超薄Si3N4/SiO2叠层栅介质可靠性研究

实验成功地制备出等效氧化层厚度为亚2nm的Nitride/Oxynitride(N/O)叠层栅介质难熔金属栅电极PMOS电容并对其进行了可靠性研究.实验结果表明相对于纯氧栅介质而言,N/O叠层栅介质具有更好的抗击穿特性,应力诱生漏电特性以及TDDB特性.进一步研究发现具有更薄EOT的难熔金属栅电极PMOS电容在TDDB特性以及寿命等方面均优于多晶硅栅电极的相应结构.     

Model‐Based Analysis of the ZrO2 Etching Mechanism in Inductively Coupled BCl3/Ar and BCl3/CHF3/Ar Plasmas

The etching mechanism of ZrO₂ thin films and etch selectivity over some materials in both BCl₃/Ar and BCl3/CHF3/Ar plasmas are investigated using a combination of experimental and modeling methods. To obtain the data on plasma composition and fluxes of active species, global (0‐dimensional) plasma models are developed with Langmuir probe diagnostics data. In BCl3/Ar plasma, changes in gas mixing ratio result in nonlinear changes of both densities and fluxes for Cl, BCl2, and BCl2⁺. In this work, it is shown that the nonmonotonic behavior of the ZrO2 etch rate as a function of the BCl3/Ar mixing ratio could be related to the ion‐assisted etch mechanism and the ion‐flux‐limited etch regime. The addition of up to 33% CHF₃ to the BCl₃‐rich BCl3/Ar plasma does not influence the ZrO2 etch rate, but it non‐monotonically changes the etch rates of both Si and SiO2. The last effect can probably be associated with the corresponding behavior of the F atom density.     

Reactive Ion Etching of ITO Transparent Electrode of TFT—AMLCD in Ar／CF4 Plasma

Ｔhe pattern of ITO transparent electrode of pixel cells in TFTAMLCD is a critical step in the manufacturing process of flat panel display devices,the development of suitable plasma reactive ion etching is necessary to achieve high resolution display.In this work we investigated the Ar/CF4 plasma etching of ITO as function of different parameters.We demonstrated the ability of this plasma to etch ITO and achieved an etching rate of about 3.73nm/min,which is expected to increase for long pumping down period,and also through addition of hydrogen in the plasma.Furthermore we described the ITO etching mechanism in Ar/CF4 plasma.The investigation of selectivity showed to be very low over silicon nitride and silicon dioxide but very high over aluminum.     

Dry etching of new phase-change material Al_(1.3)Sb_3Te in CF_4/Ar plasma

正The dry etching characteristic of Al_(1.3)Sb_3Te film was investigated by using a CF_4/Ar gas mixture.The experimental control parameters were gas flow rate into the chamber,CF_4/Ar ratio,the O_2 addition,the chamber background pressure,and the incident RF power applied to the lower electrode.The total flow rate was 50 sccm and the behavior of etch rate of Al_(1.3)Sb_3Te thin films was investigated as a function of the CF_4/Ar ratio,the O_2 addition,the chamber background pressure,and the incident RF power.Then the parameters were optimized.The fast etch rate was up to 70.8 nm/min and a smooth surface was achieved using optimized etching parameters of CF_4 concentration of 4%,power of 300 W and pressure of 80 mTorr.     

Cl2/BCl3感应耦合等离子体GaN刻蚀侧壁形貌研究

基于感应耦合等离子体干法刻蚀技术,对采用Cl2/BCl3气体组分下GaN刻蚀后的侧壁形貌进行了研究。扫描电镜(SEM)结果表明,一定刻蚀条件下,刻蚀后GaN侧壁会形成转角与条纹状褶皱形貌。进一步实验,观察到了GaN侧壁转角形貌的形成过程;低偏压功率实验表明,高能离子轰击是GaN侧壁转角与条纹状褶皱形貌形成的原因。刻蚀过程中,掩蔽层光刻胶经过高能离子一段时间轰击后,其边缘首先出现条纹状褶皱形貌,并转移到GaN侧壁上,接着转角形貌亦随之出现并转移到GaN侧壁上。这与已公开发表文献认为的GaN侧壁条纹状褶皱仅由于掩蔽层边缘粗糙所引起而非刻蚀过程中形成的解释不同。     

Low-Energy Oxygen Plasma Injection of 2D Bi2Se3 Realizes Highly Controllable Resistive Random Access Memory

Resistive random access memory (RRAM) based on ultrathin 2D materials is considered to be a very feasible solution for future data storage and neuromorphic computing technologies. However, controllability and stability are the problems that need to be solved for practical applications. Here, by introducing a damage-less ion implantation technology using ultralow-energy plasma, the transport mechanisms of space charge limited current and Schottky emission are successfully realized and controlled in RRAM based on 2D Bi₂Se₃ nanosheets. The memristors exhibit stable resistive switching behavior with a high resistive switching ratio (>10⁴), excellent cycling endurances (300 cycles), and great retention performance (>10⁴ s). The reliability and controllability of Bi₂Se₃ memory endowed by oxygen plasma injection demonstrate the great potential of this ultralow-energy ion implantation technology in the application of 2D RRAM.     

Reactive-ion etching of Ge2Sb2Te5 in CF4/Ar plasma for non-volatile phase-change memories

Etching of Ge₂Sb₂Te₅ (GST) is a critical step in the fabrication of chalcogenide random access memories. In this paper, the etch characteristics of GST films were studied with a CF₄/Ar gas mixture using a reactive-ion etching system. We observed a monotonic decrease in etch rate with decreasing CF₄ concentration indicating its importance in defining the material removal rate. Argon, on the other hand, plays an important role in defining the smoothness of the etched surface and sidewall edge acuity. We have studied the importance of gas mixture and RF power on the quality of the etched film. The smoothest surfaces and most vertical sidewalls were achieved using a CF₄/Ar gas mixture ratio of 10/40, a background pressure of 80 mTorr, and power of 200 W.     

Preparation of (Pb0.88La0.12)TiO3 thin films for dynamic random access memory by low pressure-metalorganic chemical vapor deposition

La-modified lead titanate (PLT) thin films were prepared by hot-wall type low pressure-metalorganic chemical vapor deposition method. Pb(dpm)₂, La(dpm)₃, and titanium tetraisopropoxide were used as source materials. The films were deposited at 500°C under the low pressure of 1000 mTorr and then annealed at 650°C for 10 min in oxygen ambient. Sputter-deposited platinum electrodes and 180 nm thick PLT thin films were employed to form MIM capacitors with the best combination of high charge storage density (26.7 μC/cm² at 3V) and low leakage current density (1.5 × 10^-7 A/cm² at 3V). The measured dielectric constant and dielectric loss were 1000∼1200 and 0.06∼0.07 at zero bias and 100 kHz, respectively.     

On the etching mechanism of ZrO2 thin films in inductively coupled BCl3/Ar plasma

The etching mechanism of ZrO₂ thin films in BCl₃/Ar plasma was investigated using a combination of experimental and modeling methods. It was found that an increase in the Ar mixing ratio causes the non-monotonic behavior of the ZrO₂ etch rate which reaches a maximum of 41.4 nm/min at about 30-35% Ar. Langmuir probe measurements and plasma modeling indicated the noticeable influence of a BCl₃/Ar mixture composition on plasma parameters and active species kinetics that results in non-linear changes of both densities and fluxes for Cl, BCl₂ and . From the model-based analysis of surface kinetics, it was shown that the non-monotonic behavior of the ZrO₂ etch rate can be associated with the concurrence of chemical and physical pathways in ion-assisted chemical reaction.