胍离子对铜化学机械抛光的影响
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摘要
对铜晶圆进行化学机械抛光(CMP),溶液组成和工艺条件为:胶体二氧化硅(平均粒径85 nm)5%(质量分数),30%H_2O_2 5 mL/L,胍离子(Gnd+,由碳酸胍GC或盐酸胍GC提供)适量,抛光压力5.2 kPa,抛头转速87 r/min,抛光盘转速93 r/min,抛光液体积流速300 mL/min,时间1 min。研究了抛光液中Gnd~+浓度对铜去除速率的影响,通过电化学方法及X射线光电子能谱分析了Gnd~+在铜表面的作用机制,探讨了Gnd~+对铜CMP后表面粗糙度的影响机制。一方面,随抛光液中GC浓度的升高,铜的去除速率增大,GC浓度为80 mmol/L时满足去除速率高于200 nm/min的要求;另一方面,Gnd+的引入不仅加剧了铜晶圆表面的化学腐蚀,而且使抛光液在铜晶圆表面的接触角增大,铜晶圆抛光后表面粗糙度增大。
Chemical mechanical polishing(CMP) of copper wafer was conducted in a solution containing colloidal silica with an average size of 85 nm 5 wt.%, 30% H_2O_2 5 mL/L, and a suitable amount of guanidine ion(Gnd~+, comes from guanidine carbonate or guanidine hydrochloride which were abbreviated as GC and GH respectively) at a pressure of 5.2 kPa, a rotation rate of polishing head 87 r/min, a rotation rate of polishing disc 93 r/min, and a volumetric flow rate of polishing solution 300 mL/L for 1 min. The effect of Gnd~+ concentration in polishing solution on the removal rate of copper was studied. The mechanism of the action of Gnd+ on copper surface during CMP was analyzed by electrochemical method and X-ray photoelectron spectroscopy. The mechanism of the effect of Gnd~+ on surface roughness of copper after CMP was discussed. On one hand, the removal rate is increased with the increasing of Gnd~+ concentration in polishing solution, and meets the requirement of beyond 200 r/min when the Gnd+ concentration is 80 mmol/L; on the other hand, the addition of Gnd~+ not only exacerbates the chemical corrosion of copper wafer surface, but also increases the contact angle between the polishing solution and copper surface, leading to an increase in surface roughness of the polished copper wafer.
Chemical mechanical polishing(CMP) of copper wafer was conducted in a solution containing colloidal silica with an average size of 85 nm 5 wt.%, 30% H_2O_2 5 mL/L, and a suitable amount of guanidine ion(Gnd~+, comes from guanidine carbonate or guanidine hydrochloride which were abbreviated as GC and GH respectively) at a pressure of 5.2 kPa, a rotation rate of polishing head 87 r/min, a rotation rate of polishing disc 93 r/min, and a volumetric flow rate of polishing solution 300 mL/L for 1 min. The effect of Gnd~+ concentration in polishing solution on the removal rate of copper was studied. The mechanism of the action of Gnd+ on copper surface during CMP was analyzed by electrochemical method and X-ray photoelectron spectroscopy. The mechanism of the effect of Gnd~+ on surface roughness of copper after CMP was discussed. On one hand, the removal rate is increased with the increasing of Gnd~+ concentration in polishing solution, and meets the requirement of beyond 200 r/min when the Gnd+ concentration is 80 mmol/L; on the other hand, the addition of Gnd~+ not only exacerbates the chemical corrosion of copper wafer surface, but also increases the contact angle between the polishing solution and copper surface, leading to an increase in surface roughness of the polished copper wafer.
引文
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[3]CHOU Y S,YEN S C,JENG K T.Fabrication of ruthenium thin film and characterization of its chemical mechanical polishing process[J].Materials Chemistry and Physics,2015,162:477-486.
[4]ROULE A,AMUNTENCEI M,DERONZIER E,et al.Seed layer enhancement by electrochemical deposition:the copper seed solution for beyond[J].Microelectronic Engineering,2007,84(11):2610-2614.
[5]CHYAN O,ARUNAGIRI T N,PONNUSWAMY T.Electrodeposition of copper thin film on ruthenium:a potential diffusion barrier for Cu interconnects[J].Journal of the Electrochemical Society,2003,150(5):C347-C350.
[6]JIANG L,HE Y Y,LI Y Z,et al.Effect of ionic strength on ruthenium CMP in H2O2-based slurries[J].Applied Surface Science,2014,317:332-337.
[7]AMANAPU H P,SAGI K V,TEUGELS L G,et al.Role of guanidine carbonate and crystal orientation on chemical mechanical polishing of ruthenium films[J].ECS Journal of Solid State Science and Technology,2013,2(11):P445-P451.
[8]李海龙,刘玉岭,王辰伟,等.阻挡层CMP中盐酸胍对铜和钽抛光速率的影响[J].微纳电子技术,2013,50(9):586-591.
[9]杜义琛,周建伟,王辰伟,等.盐酸胍对钌在含双氧水的二氧化硅水溶胶中化学机械抛光的影响[J].电镀与涂饰,2017,36(17):915-919.
[10]TURK M C,ROCK S E,AMANAPU H P,et al.Investigation of percarbonate based slurry chemistry for controlling galvanic corrosion during CMP of ruthenium[J].ECS Journal of Solid State Science and Technology,2013,2(5):P205-P213.
[11]DU Y C,WANG C W,ZHOU J W,et al.Effect of guanidinium ions on ruthenium CMP in H2O2-based slurry[J].ECS Journal of Solid State Science and Technology,2017,6(8):P521-P525.
[12]TROMANS D.Aqueous potential-pH equilibria in copper-benzotriazole systems[J].Journal of The Electrochemical Society,1998,145(3):L42-L45.
[13]DU T B,LUO Y,DESAI V.The combinatorial effect of complexing agent and inhibitor on chemical mechanical planarization of copper[J].Microelectronic Engineering,2004,71(1):90-97.
[14]MCINTYRE N S,SUNDER S,SHOESMITH D W,et al.Chemical information from XPS-applications to the analysis of electrode surfaces[J].Journal of Vacuum Science and Technology,1981,18(3):714-721.
[15]MORETTI G,FIERRO G,JACONO M L,et al.Characterization of CuO-ZnO catalysts by X-ray photoelectron spectroscopy:precursors,calcined and reduced samples[J].Surface and Interface Analysis,1989,14(6/7):325-336.
[16]FISHER G B,ERIKSON N E,MADEY T E,et al.X-ray photoemission study of physically adsorbed SF6[J].Surface Science,1977,65(1):210-228.
[17]ZHANG K,NIU X H,WANG C W,et al.Effect of chelating agent and ammonium dodecyl sulfate on the interfacial behavior of copper CMP for GLSI[J].ECS Journal of Solid State Science and Technology,2018,7(9):P509-P517.
[18]CHENG J,WANG T Q,LU X C.Galvanic corrosion inhibitors for Cu/Ru couple during chemical mechanical polishing of Ru[J].ECS Journal of Solid State Science and Technology,2017,6(1):P62-P67.