Texture and electromigration lifetime improvements in layered Al-alloy metallization with underlying Ti by controlling water adsorption on SiO2 substrates

The effect of residual gas constituents and substrate temperature during Ti sputtering on the texture of TiN/Ti films deposited on SiO₂/Si substrates has been investigated. The Ti(002) and TiN(111) preferred texture of the films deposited at 350°C was found to be improved drastically by increasing the H₂O partial pressure from 1×10⁻⁹ to 3×10⁻⁸ Torr. Both of the Ti(002) and TiN(111) textures showed a similar H₂O partial pressure and substrate temperature dependence because of the epitaxial transfer between these planes. The improved Ti(002) texture was attributed to the self-assembly of Ti atoms on the SiO₂ surface, which had a low surface free energy due to the formation of surface OH groups. Two kinds of layered Al-alloy interconnects, AlSiCu/Ti/TiN/Ti and AlCu/TiN/Ti, were fabricated with the highly textured TiN/Ti film, and their Al(111) texture and electromigration lifetime were then evaluated. It was confirmed that both of the interconnects have strong Al(111) texture and longer EM lifetimes.     

Effects of deposition conditions of Al and Ti underlayer on electromigration reliability for deep-submicron interconnect metallization

We have studied the effects of Ti underlayer (collimated Ti vs. standard Ti) and Al deposition power (12 KW vs. 6 KW) on the electromigration (EM) lifetime of bottom-Ti/Al-0.5wt.%Cu/Ti/TiN-top stack. The (002) texture of standard Ti (s-Ti) was stronger than that of collimated Ti (c-Ti). The Al stack prepared with s-Ti underlayer, which had the stronger Al (111) texture and more uniform grain size distribution, showed better EM lifetime than the same with c-Ti underlayer, independent of the Al deposition power. The Al stack prepared with an Al deposition power of 6 KW was also found to show better EM lifetime than the same with a 12 KW deposition power, independent of the type of Ti underlayer. Longer deposition time for low power sputtering resulted in the stronger Al (111) texture, larger median grain size, and more uniform Ti−Al reaction layer. Finally, the effects of Ti underlayer and Al deposition power on the EM lifetime of Al-0.5%Cu films could be well explained by the grain size distribution and Al (111) texture, which is closely related to the underlying-Ti (002) texture.     

Improvement in Power Durability of Al Electrode Films Used in SAW Devices by Zr Additive and Ti Underlayer

In order to improve the power durability of Al electrode films and obtain fine-dimensional control in high-frequency surface acoustic wave (SAW) devices, two-layered Al-Zr/Ti electrode films were investigated on 128°Y−X LiNbO₃ substrates by sputter deposition. The results indicated that Al-Zr/Ti electrode films had improved electromigration (EM) reliability compared to Al/Ti electrode films and their lifetime was strongly dependent on the microstructure and Zr concentration. Al-Zr/Ti electrode films with a strong Al (111) texture exhibited longer EM lifetime than polycrystalline films. The Al-Zr/Ti electrode film with an ideal Zr concentration of 0.2 wt.% and a sputtering pressure of 0.25 Pa had a strong Al (111) texture, and its lifetime was approximately four times longer than that of Al/Ti films tested at a current density of 5 × 10⁷ A/cm² at 200°C. Furthermore, the Al-Zr/Ti films were easily etched in reactive ion etching and fine-dimensional control was realized during pattern replication for high-frequency SAW devices.     

溅射沉积功率对PZT薄膜的组分、结构和性能的影响

用射频(RF)溅射法在镀LaNiO3(LNO)底电极的Si片上沉积PbZr0.52 Ti0.48 O3(PZT)铁电薄膜，沉积过程中基底温度为370℃，然后在大气环境中对沉积的PZT薄膜样品进行快速热退火处理(650℃，5min)．用电感耦合等离子体发射光谱(ICP-AES)测量其组分，X射线衍射(XRD)分析PZT薄膜的结晶结构和取向，扫描电子显微镜(SEM)分析薄膜的表面形貌和微结果，RT66A标准铁电综合测试系统分析Pt／PZT／LNO电容器的铁电与介电特性，结果表明，PZT薄膜的组分、结构和性能都与溅射沉积功率有关．     

Effect of the underlayer on the microstructure and surface evolution in Al-0.5wt.%Cu polycrystalline thin films

The effects of the Ti underlayer on the evolution of grain morphology, crystallographic texture, and surface roughness of Al-0.5wt.%Cu thin films during sputter deposition have been characterized. In comparison to SiO₂ substrates, Ti underlayers reduce the AlCu thickness at which film continuity is reached, reduce the AlCu columnar grain size, and allow exact Al (111) fiber texture development. The AlCu films on both Ti and SiO₂ are primarily randomly oriented at early stages of deposition. A near-(111) Al fiber texture in AlCu/SiO₂ films initiates during the preferential growth of ≈5° offset islands prior to film continuity, seeding the near Al (111) texture as film continuity is reached. The exact Al (111) fiber orientation in AlCu/Ti films develops after film continuity. The near-(111) and exact (111) fiber textures strengthen with further deposition due to combined normal and abnormal grain growth. Film coalescence and grain growth lead to a significant smoothing effect during the early stages of deposition.     

PLD法制备高介电调谐率的纳米晶BZT薄膜

用脉冲激光沉积工艺制备了Ba(ZrxTi1-x)O3(x=0.25,0.30简称BZT25和BZT30)介电薄膜。在650℃原位退火10 min,薄膜为(111)取向柱状生长的晶粒,取向度分别为0.45和0.75。BZT25和BZT30薄膜的平均晶粒尺寸分别为50 nm和60 nm。在室温、1 MHz和3×105 V/cm条件下,BZT25的最大εr和调谐率分别达到563和65%,BZT30的最大εr和调谐率分别达到441和57%。薄膜为(111)取向生长,主要是基于薄膜与底电极Pt界面层立方相结构Pt3Ti的诱导,即(111)Pt3Ti和(111)BZT的晶格匹配。     

Ion bombardment-induced high orientation of Al/Ti films for surface acoustic wave device applications

Al/Ti films were deposited on 128° Y-X LiNbO₃ substrates by electron-beam (e-beam) deposition. Low-energy Ar ion beam bombardment was employed during the Ti underlayer deposition. Influence of low-energy beam bombardment on the texture of Al/Ti films was investigated by x-ray diffraction (XRD) analysis. It was found that Al films deposited on Ar-ion bombarded Ti underlayers possessed excellent (111) texture. With the textured Al/Ti films, a 2.3-GHz range image-impedance connection surface acoustic wave (SAW) filter was successfully fabricated.     

衬底负偏压及溅射功率对SiO_2/Cu薄膜形貌的影响

采用射频磁控溅射镀膜技术,分别以不同的衬底负偏压和射频溅射功率下在p型Si(100)基片上制备了SiO2/Cu薄膜。用原子力显微镜(AFM)对薄膜的表面形貌进行扫描分析,实验结果表明,衬底负偏压和射频溅射功率对SiO2/Cu薄膜的表面形貌都有显著的影响。衬底负偏压在0～15 V内,薄膜表面颗粒尺寸和均方根粗糙度都随着衬底负偏压的增大呈减小的趋势,而溅射功率在100～200 W内,薄膜表面颗粒尺寸和均方根粗糙度都随溅射功率的升高呈增大的趋势。成膜初期是层状生长模式,后期为岛状生长模式,整个成膜过程是典型的层岛生长模式。     

Deposition of polycrystalline AIN thin films by coherent magnetron sputtering at temperatures <80°C

A1N thin films were reactively deposited onto Al layers on negatively biased glass and Si substrates at temperatures <80°C by coherent magnetron sputtering. The low temperature deposition of the films without substrate heating was achieved by increasing the target-to-substrate distance, and therefore the heating effect of the plasma is relieved. The microstructure and morphology of the films deposited at different bias voltage and target-to-substrate distance were investigated. The films are amorphous when the target is far from the substrate for a bias voltage up to −320V. When the target-to-substrate distance is decreased to 17 cm a preferred (002) orientation of AIN films is observed at a bias voltage of −240 V. Additionally, the deposited films have specular reflectance and no voids can be observed. This low temperature technique can be used for applications in acoustic wave devices due to the improved homogeneity of the films and step coverage.     

Roughness and texture correlation of Al films

Titanium films prepared by standard direct-current (DC) magnetron physical vapor deposition (PVD) and ionized metal plasma PVD (I-PVD), with Al (0.5wt.%Cu) films on them, were studied. The surface roughness, reflectivity, and crystalline texture of Ti on SiO₂/Si and Al on TiN/Ti/SiO₂/Si were investigated with the same thickness of Al, TiN, and Ti. The surface roughness of Al films with Ti/TiN underlayers was found to be capable of monitoring Al(111) texture. So, the reflectivity of Al/TiN/Ti film stack can be used as a quick monitor for the electromigration (EM) lifetime.     

DC Magnetron-Sputtered Mo Thin Films with High Adhesion,Conductivity and Reflectance

The main challenge in the deposition of molybdenum thin films for high efficiency in copper indium gallium selenide (CIGS) modules lies in gaining an adherent coating without compromising conductivity and reflectance characteristics. In this study, Mo thin films were deposited on soda-lime glass by DC magnetron sputtering at different deposition power (55, 100, 200 and 300 W) and with high working gas pressure (2 and 4 Pa). Analytical techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM) and Hall effect were employed to analyze the structure, morphology and electrical resistivity of the deposited films. Ultraviolet–visible (UV–Vis) spectrometry was performed to measure the reflectance and a cross-hatch adhesion tape test was employed to determine the adhesion behavior of deposited films. With higher sputtering power and reduced gas pressure, an increase in the crystallite size of the deposited films was observed. Films deposited at higher gas pressure were found with tensile stresses and higher adhesion with the substrate. The van der Pauw method reveals an increase in conductivity at high power and low gas pressure. Improved reflectance was achieved at moderate sputtering power and low gas pressure.     

FBAR用高质量AlN薄膜制备

采用直流磁控反应溅射法,在基片表面引入RF偏置,在Si(111)衬底上成功制备了(002)向AlN薄膜。使用高分辨率X射线衍射仪(XRD)来表征薄膜质量。当RF偏置从0 W变化到20 W时,XRD测试(002)摇摆曲线的半高宽有着显著的变化。当RF偏置为15 W时,AlN薄膜表现出了良好的(002)生长取向。实验结果表明,适当的RF偏置能够提高Al原子和N原子反应时的活性,促进AlN薄膜的(002)择优生长。该溅射方案应用于薄膜体声波谐振器(FBAR)谐振器工艺加工,成功制作了Q值为300,机电耦合系数为5%的FBAR样品。     

RF溅射ZnO薄膜工艺与结构研究

通过RF磁控溅射在Si(100)基片上制备了ZnO薄膜,并研究了磁控溅射中各生长参数,如衬底温度、氧分压及后处理工艺等因素对ZnO薄膜微结构、表面形貌与结晶取向的影响。结果表明:溅射温度和氧分压对薄膜的微结构与择优取向有很大的影响,并对不同的溅射工艺进行了分析比较,从而确定了最佳溅射及后处理条件:RF溅射温度小于300℃,功率为50W,ψ(Ar:O2)为20:5,退火温度550~600℃,并获得了c轴择优取向的ZnO薄膜。     

BST薄膜的微结构研究

采用射频磁控溅射法在 Pt/Ti/SiO2/Si 衬底上制备了钛酸锶钡(BST)薄膜。利用 X 射线光电子能谱(XPS)、X射线衍射(XRD)分别研究了 BST 薄膜的成分、晶体结构。用优化的成膜工艺制备出成分与靶材基本一致,具有钙钛矿结构的 BST 多晶薄膜。利用扫描力显微镜中的压电模式(PFM)观察到了 BST 薄膜中的 a 畴和 c 畴,初步确定在 BST薄膜中多畴转变为单畴的临界尺寸为 28~33 nm。     

ZnO光电导紫外探测器的制备和特性研究

以Si(111)衬底,用脉冲激光沉积(PLD)法制得C轴高度择优取向的ZnO薄膜,并利用剥离技术制备了ZnO光导型紫外探测器.Al叉指状电极是由平面磁控溅射技术沉积得到的.对Al/ZnO/Al的伏安特性和紫外光响应的研究表明,金属铝和ZnO能形成很好的欧姆接触,紫外探测器的电阻值在100KΩ左右.在紫外区域,其5V偏压下的光响应度为0.5A/W.     

The effects of substrate bias,substrate temperature,and pulse frequency on the microstructures of chromium nitride coatings deposited by pulsed direct current reactive magnetron sputtering

Recently, great attention has been devoted to the pulsed direct current (DC) reactive magnetron sputtering technique, due to its ability to reduce arcing and target poisoning, and its capability of producing insulating thin films. In this study, chromium nitride (CrN) coatings were deposited by the bipolar symmetric pulsed DC magnetron reactive sputtering process at different pulse frequency, substrate bias voltage, and the substrate temperature. It was observed that the texture of CrN changed from (111) to (200) as substrate temperature increased to 300°C as deposited at 2 kHz without substrate bias. With increasing pulsing bias and pulse frequency of target, predominated (200) orientation of CrN film was shown due to the ion bombardment/channeling effect to preferentially sputter those unaligned planes. For the CrN coatings deposited with pulsed biasing, the grain size decreased with increasing pulse frequency and substrate bias, whereas the surface roughness showed a reverse trend. The deposition rate of the CrN films decreased with increasing pulse frequency. It was concluded that the pulse frequency, substrate bias, and substrate temperature played important role in the texture, microstructure, and surface roughness of the CrN coatings deposited by the pulsed DC magnetron sputtering process.     

Microstructure and corrosion resistance of room-temperature RF sputtered Ta2O5 thin films

The connection between the chemical corrosion resistance and the microstructure of the Ta₂O₅ thin films prepared at room temperature by a RF magnetron sputtering technique on Si substrates has been investigated. We find that the microstructure of the films changes with different RF sputtering power, and is responsible for the degradation of the corrosion resistance in HF solutions. The deposited films are amorphous and porous when the RF power is low. A preferred orientation toward (200) β-Ta₂O₅ can be observed when the RF power is increased to 150 W. In addition, the films deposited under this condition are dense and are consequently more resistant to the attack of chemicals. AT an RF power of 300 W the corrosion resistance of the films declines due to an increase of the exposed pore surface to the HF solution.     

c轴择优取向ZnO薄膜RF溅射工艺研究

通过射频磁控溅射在Si(100)基片上制备了ZnO薄膜,该文着重研究了磁控溅射中各生长参数如衬底温度、氧分压及后处理工艺等因素对氧化锌薄膜结晶性能、表面形貌、择优取向与微结构的影响,并对溅射工艺与取向、结构的关系进行了分析比较,从而确定了最佳溅射及后处理条件并获得了c轴择优取向的ZnO薄膜。     

Silicon Nitride Films Deposited by RF Sputtering for Microstructure Fabrication in MEMS

In the present work, we report silicon nitride films deposited by a radio- frequency (RF) sputtering process at relatively low temperatures (<260°C) for microelectromechanical system (MEMS) applications. The films were prepared by RF diode sputtering using a 3-inch-diameter Si₃N₄ target in an argon ambient at 5 mTorr to 20 mTorr pressure and an RF power of 100 W to 300 W. The influence of the film deposition parameters, such as RF power and sputtering pressure, on deposition rate, Si-N bonding, surface roughness, etch rate, and stress in the films was investigated. The films were deposited on single/double-side polished silicon wafers and transparent fused-quartz substrates. To explore the RF-sputtered silicon nitride film as a structural material in MEMS, microcantilever beams of silicon nitride were fabricated by bulk, surface, and surface-bulk micromachining technology. An RF-sputtered phosphosilicate glass film was used as a sacrificial layer with RF-sputtered silicon nitride. Other applications of sputtered silicon nitride films, such as in the local oxidation of silicon (LOCOS) process, were also investigated.     

PECVD制备纳米晶多晶硅薄膜

以Si(100)为衬底,采用磁控溅射和射频等离子体增强化学气相沉积系统制备了Si(100)/Al膜/非晶Si膜结构的样品。对该样品进行Al诱导真空退火以制备多晶硅薄膜,采用X射线衍射仪(XRD)和AFM分析薄膜微结构及表面形貌。实验结果表明,在经过500℃、550℃Al诱导退火后,形成了择优取向为〈111〉晶向的多晶硅薄膜。AFM给出了550℃退火后薄膜表面形貌,为100～200nm大小的圆丘状硅晶粒,密集排列在薄膜表面;并对Al诱导真空退火晶化的机理进行了分析。