氮化硅的ECCP刻蚀特性研究

本文对氮化硅的增强电容耦合等离子刻蚀进行研究,为氮化硅刻蚀工艺的优化提供参考。针对SF_6+O_2气体体系,通过设计实验考察了功率、压强、气体比、氦气等对刻蚀速率和均一性的影响,并对结果进行机理分析和讨论。实验结果表明:功率越大,刻蚀速率越大,与源极射频电力相比,偏置射频电力对刻蚀速率的影响更为显著;压强增大,刻蚀速率增大,但压强增大到一定程度后,刻蚀速率基本不变,刻蚀均匀性随着压强增大而变差;在保证SF_6/O_2总流量保持不变下,O_2的比例增大,刻蚀速率先增大后减小,刻蚀均匀性逐步变好;He的添加可以改善刻蚀均匀性,但He的添加量过多时,会造成刻蚀速率降低。     

IGZO-TFT钝化层三元复合结构过孔刻蚀

IGZO-TFT钝化层设计三元复合过孔结构,出现了20%过孔相关不良。本文以CF4/O2为反应气体,采用控制变量法,从功率、气体成分和比例、压力等方面对氧化物TFT钝化层的电感耦合等离子体刻蚀机理进行研究。当钝化层为SiO2或SiNx单组分时,氧气可以促进刻蚀反应;随着CF4/O2比例增加,刻蚀速率先增大后趋于稳定,并且当CF4/O2=15/8时,刻蚀速率和均一性达到最优;与源功率相比,提高偏压功率在提升刻蚀速率中起主导作用,同时均一性控制在15%以内;当压力在4Pa以内时,刻蚀速率随着压力的降低而增加。据此分析,对复合结构SiNx/SiO2、SiO2/SiNx、SiNx/SiO2/SiNx的刻蚀过程进行优化,得到了形貌规整、无残留物的过孔,过孔相关不良得到100%改善。     

6H-SiC体材料在SF_6/O_2混合气体中的ICP刻蚀

采用SF6/O2作为刻蚀气体,对单晶6H-SiC材料的感应耦合等离子体(ICP)刻蚀工艺进行了研究。分析了ICP功率、偏置电压、气体混合比等工艺参数对刻蚀速率和刻蚀质量的影响。结果表明,刻蚀速率随着ICP功率及偏置电压的增大而提高,刻蚀表面质量随偏置电压及O2的含量的增大而降低,而ICP功率的变化对刻蚀质量影响不大。混合气体中O2含量为20%时刻蚀速率达到最大值,同时加入氧气后形成易于充电的SiFxOy中间层,从而促进了微沟槽的形成。     

大尺寸TFT-LCD ECCP刻蚀工艺低耗整合

为简化大尺寸液晶面板四次光刻法的刻蚀工艺、减少有毒气体使用、降低射频功率消耗,在2 200mm×2 500mm大尺寸玻璃上,采用正交实验设计,验证了功率、气压、反应气体和比例等参数对各刻蚀步骤刻蚀速率、均一性和选择比的影响关系,从而得到各膜层的最佳工艺条件。在Enhance Cathode Couple Plasma Mode(ECCP)刻蚀模式下,采用新刻蚀条件合并薄膜晶体管有源区非晶硅、光刻胶、湿刻后源极和漏极剩余金属钼以及沟道非晶硅层干法刻蚀。利用扫描电子显微镜(SEM)对薄膜电学特性进行测试,结果显示,金属钼的刻蚀可以采用一次两步干法刻蚀,"2干2湿"刻蚀可以整合为"1干1湿"。整合后总刻蚀工艺时间减少16s,减少了氯气使用量和RF总功率。试验改进了均一性和刻蚀率,同时对于下底衬具有良好的选择比,保持了良好的形貌,为大批量"1干1湿"生产提供了依据。     

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。     

Cl_2/BCl_3ICP刻蚀GaN基LED的规律研究

研究了用Cl2/BCl3刻蚀GaN基LED中,工艺参数对GaN刻蚀速率、刻蚀侧壁和GaN与SiO2刻蚀选择比的影响。研究结果表明,刻蚀速率随着ICP功率和压强的增大先增大继而减小,随RF功率的增大单调增大;刻蚀选择比随ICP功率增大单调减小,随压强增大而增大。还研究了刻蚀速率和选择比与气体比例变化的关系。刻蚀SEM图表明,压强和RF功率增大会使刻蚀垂直度增大。     

薄膜晶体管平坦化层干法刻蚀工艺的研究

为了降低薄膜晶体管的寄生电容,一种新型平坦化材料被引入。单独采用反应离子刻蚀(RIE)或增强电容耦合等离子刻蚀(ECCP)模式刻蚀该平坦化层均无法获得满意的工艺效果。为此,提出了将RIE和ECCP相结合的方法用于新型平坦化层的刻蚀。实验结果表明:当平坦化层厚度为2.0μm时,先以RIE模式7kW/20Pa条件刻蚀1.5μm,再以ECCP模式5kW+4kW/8Pa条件继续刻蚀平坦化层及其下方的氮化硅,刻蚀出的过孔图形表面光滑,氮化硅层无底切,平坦化层孔径均值6.12μm。本研究结果为后续采用该平坦层材料的高分辨率、低功耗产品的设计和生产打下了坚实基础。     

ICP技术在化合物半导体器件制备中的应用

介绍了ICP刻蚀工艺技术原理和在化合物半导体器件制备中的应用,包括ICP刻蚀技术中的低温等离子体的形成机理、等离子体与固体表面的相互作用等,并对影响ICP刻蚀结果的因素进行了分析.研究了不同的工艺气体配比、腔体工作压力、ICP源功率和射频源功率对刻蚀的影响,并初步得到了一种稳定、刻蚀表面清洁光滑、图形轮廓良好、均匀性较好和刻蚀速率较高的干法刻蚀工艺.     

用于垂直腔面发射激光器的GaAs/AlGaAs的ICP刻蚀工艺研究

采用电感耦合等离子体(ICP)刻蚀设备对应用于垂直腔面发射激光器的GaAs/AlGaAs材料进行刻蚀工艺研究。该刻蚀实验采用光刻胶作为刻蚀掩模,Cl2/BCl3作为刻蚀工艺气体,通过实验分析总结了ICP源功率、射频偏压功率和腔体压强对GaAs/AlGaAs材料和掩模刻蚀速率的影响。利用扫描电子显微镜观察不同参数条件对样品侧壁垂直度和底部平坦度的影响。最终在保证高刻蚀速率的前提下,通过调整优化各工艺参数,得到了侧壁光滑、底部平坦的圆台结构。     

基于金刚石钝化散热的栅区微纳尺度刻蚀研究

片内热积累效应严重制约GaN器件向高功率密度应用发展,金刚石钝化散热结构的GaN器件热管控技术已成为目前研究重点,而金刚石栅区高精度刻蚀和控制是实现该热管理技术应用的关键工艺难点。因此,本文采用电感耦合等离子体（ICP）刻蚀技术,以氮化硅作为刻蚀掩膜,对纳米金刚石薄膜进行栅区微纳尺度刻蚀工艺研究,系统分析了刻蚀气体、组分占比、射频功率等工艺参数对刻蚀速率的影响。结果表明,ICP源功率与氧气流量对刻蚀速率有增强作用,Ar与CF₄的加入对刻蚀过程具有调控作用。最终提出了基于等离子体刻蚀技术的高精度微纳尺度金刚石钝化薄膜刻蚀方法,对金刚石集成GaN器件热管理和金刚石高精度刻蚀技术具有重要的指导意义。     

4H-SiC材料干法刻蚀工艺的研究

鉴于SiC材料具有很强的稳定性以及湿法刻蚀的种种缺点,目前主要使用干法刻蚀来刻蚀SiC材料。但是干法刻蚀后样品表面的粗糙度对器件的性能有一定的影响。针对这一问题,采用电感耦合等离子体-反应离子刻蚀技术,对SiC材料进行SF₆/O₂混合气体和SF₆/CF₄/O₂混合气体的刻蚀,并且探究了压强、ICP功率和混合气体比例对样品表面粗糙度的影响。实验结果表明使用SF₆/O₂混合气体刻蚀后,样品的表面平整度较好。在一定RIE功率条件下,当ICP功率为700 W、压强为20 mT和SF₆/O₂为50/40 sccm时,样品表面的粗糙度最小。     

Reactor characterization for a process to etchSi3N4 formed on thin SiO2

A plasma etching process for patterning LPCVD (low-pressure chemical vapor deposition) Si₃N₄ which has been formed on thin thermally grown SiO₂ has been developed and characterized with an Applied Materials 8110 batch system using 100-mm-diameter silicon wafers. To fulfill the primary process objectives of minimal critical dimension (CD) loss (~0.08 μm), vertical profiles after etch, retention of some of the underlying thermal SiO₂, and batch etch uniformity, the reactor has been characterized by evaluating the effects of variation of reactor pressure (15 to 65 mTorr), O₂ concentration by flow rate (30 to 70%) of an O₂/CHF₂ mixture, and DC bias voltage (-200 to -550 V). Analysis of the resulting etch rate, etch uniformity, dimensional, and profile data suggests that satisfactory processing may be achieved at low reactor pressure (~25 mTorr), 50-60% O₂ by flow rate in O₂/CHF₃, and low DC bias (-200 to -250 V)     

Study of etch rate characteristics of SF6/He plasmas byresponse-surface methodology: effects of interelectrode spacing

The characteristics of SF₆/He plasmas which are used to etch Si₃N₄ have been examined with experimental design and modeled empirically by response-surface methodology using a Lam Research Autoetch 480 single-wafer system. The effects of variations of process gas flow rate (20-380 sccm), reactor pressure (300-900 mtorr). RF power (50-450 W at 13.56 MHz), and interelectrode spacing (8-25 mm) on the etch rates of LPCVD (low-pressure chemical vapor deposition) Si₃N₄, thermal SiO₂, and photoresist were examined at 22±2°C. Whereas the etch rate of photoresist increases with interelectrode spacing between 8 and 19 mm and then declines between 19 and 25 mm, the etch rate of Si₃N ₄ increases smoothly from 8 to 25 mm, while the etch rate of thermal SiO₂ shows no dependence on spacing between 8 and 25 mm. The etch rates of all three films decrease with increasing reactor pressure. Contour plots of the response surfaces for etch rate and etch uniformity of Si₃N₄ as a function of spacing and flow rate at constant RF power (250 W) display complex behavior at fixed reactor pressures. A satisfactory balance of etch rate and etch uniformity for Si₃N₄ is predicted at low reactor pressure (~300 mtorr), large electrode spacing (12-25 mm), and moderate process gas flow rates (20-250 sccm)     

Development of a TiW plasma etch process using a mixture experimentand response surface optimization

The characteristics of SF₆/He plasmas used to etch TiW have been studied with statistically designed experiments using a Tegal 804 single wafer system. Two processes were developed using both positive and negative photoresist as the mask material for etching TiW. The goal was to consolidate both processes into one. A two-phase experimental approach was taken to generate the processes. In phase 1 a fractional factorial screening experiment was used to identify key factors, and in phase 2 a mixture experiment was used for process optimization. The fractional factorial experiment was initially used to study the effects of reactor pressure, RF power, SF₆/He gas ratio, overetch time, and hard bake. The results of this initial experiment were used to identify the appropriate levels for the main process parameters. Then, at these parameter levels, a mixture experiment was conducted using the partial pressures of SF₆, He, and the nitrogen ballast as the design variables. Since the total pressure in the system is fixed, these three variables are the components of a mixture, and thus form a constrained design space for the experiment. Quadratic and special cubic response surface models were generated for the following responses: TiW etch rate, photoresist etch-rate, selectivity between the TiW and photoresist, uniformity of all etch rates and selectivities, and critical dimension control for the photoresist and TiW. Contour plots for all responses as a function of the partial pressure of SF₆, He, and nitrogen ballast were generated. The contours from these empirical models were analyzed jointly to optimize the processes     

Interlevel dielectric via etch process monitoring by atomic forcemicroscopy

The use of AFM for in-line monitoring of an interlevel dielectric via plasma etching step is reported. By comparing etch depths, to via types contacting both Au- and W-based metals, the AFM can non-destructively determine whether micrometre-sized vias have been cleared. Owing to the etch selectivity of the SF₆/O₂ plasma, the Au-based ohmic metal acts as an etch stop whereas the W-based refractory gate contact continues to etch     

ICP etching of SiC

A number of different plasma chemistries, including NF₃/O₂, SF₆/O₂, SF₆/Ar, ICl, IBr, Cl₂/Ar, BCl₃/Ar and CH₄/H₂/Ar, have been investigated for dry etching of 6H and 3C–SiC in an inductively coupled plasma tool. Rates above 2000 Å cm⁻¹ are found with fluorine-based chemistries at high ion currents. Surprisingly, Cl₂-based etching does not provide high rates, even though the potential etch products (SiCl₄ and CCl₄) are volatile. Photoresist masks have poor selectivity over SiC in F₂-based plasmas under normal conditions, and ITO or Ni is preferred.     

Reactive ion etching of Ta-Si-N diffusion barriers in CHF3+O2

Reactive ion etching of Ta₃₆Si₁₄N₅₀ diffusion barrier layers was performed in CHF₃+O₂ plasmas. Etch depths and rates were determined as a function of etch gas composition, cathode power, and etching time. Etching proceeds only after an initial delay which depends on gas composition and cathode power. This delay is attributed to the presence of a native surface oxide which must first be removed before etching can commence. Maximum etch rate was attained at 62.5% O₂ concentration, which also corresponds to minimum delay     

RIE模式干法刻蚀ADS产品铝腐蚀改善研究

Full-in-cell(FIC)产品信号线SD层结构为Mo-Al-Mo结构,使用Reactive Ion Etching(RIE)模式干法刻蚀设备进行N+Etch时,氯的化合物会吸附在信号线中的Al线侧壁及光刻胶的表面,当玻璃基板离开刻蚀腔体接触到空气,遇到水分发生水解反应,对Al线造成腐蚀,严重影响产品特性。本文在RIE刻蚀模式腔体内采用刻蚀条件变更改善Al腐蚀现象,通过对刻蚀的前处理步骤,后处理步骤以及去静电步骤的参数包括压强、功率和时间以及气体流量比进行实验设计并对数据进行分析。实验结果表明当后处理步骤2 000 W,O_2/SF_6比例为2 000mL·min~(-1)/50mL·min~(-1),压强为200mt(1mt=0.133Pa),Time为15s为最优条件,可以彻底改善Al腐蚀现象。此条件TFT特性方面更加优越,Dark I_(on)为1.91μA,Photo I_(off)为4.1pA。