PI衬底卷绕磁控溅射/电沉积法制备Cu膜工艺及其性能研究
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摘要
在电子产品的小型化以及液晶显示电子产品高速发展的驱动下,COF (Chip on Film)的应用市场得到了快速的扩大。COF挠性基板作为COF的重要组成部分之一,以及在LCD驱动IC中,它起到承载IC芯片、电路连通、绝缘支撑的作用。高微细线路、高安装引线位置精度及采用二层挠性覆铜板(2L-FCCL)是它突出的三大特点。二层挠性覆铜板的制备方法主要有涂布法、层压法、溅镀法。
本文采用磁控溅射法与磁控溅射电沉积法,通过在PI膜表面上直接溅射沉积Cu膜或先在PI膜表面上磁控溅射一层导电膜层后通过电沉积加厚的方法制备PI-Cu膜,利用四探针测试仪、X射线衍射仪(XRD)、扫描电镜(SEM)、原子力显微镜(AFM)等手段研究了溅射电流、工作压强、电沉积电流密度、沉积时间、过渡层等制备工艺对薄膜的电阻率、晶面择优取向、附着力、表面形貌等性能的影响。研究表明,采用磁控溅射法制备PI-Cu膜时,工作压强为0.4Pa时,较小的工作电流(小于10A),Cu膜电阻率较大,较大的工作电流(大于12A),薄膜电阻率较小,并且随着工作电流的增大,电阻率变化逐渐变小；与未施加过渡层样品的电阻率相比,施加过渡层(镍、氮化钛、二氧化钛)后,样品的薄膜电阻率有较大的降低、样品的Cu衍射峰有略微增强。施加镍或氮化钛过渡层后,薄膜电阻率比未施加过渡层样品电阻率降低值超过35%；施加镍和氮化钛过渡层后,Cu薄膜剥离强度比未施加过渡层Cu薄膜样品剥离强度大四倍以上。采用磁控溅射-电沉积法制备PI-Cu膜时,薄膜厚度越大,方块电阻和薄膜电阻率越小,薄膜厚度大于2μm时,薄膜的方块电阻与电阻率逐渐趋于稳定,其方块电阻小于0.02Ω,电阻率小于3.7μΩ×cm；相同电流密度下,随着电沉积Cu薄膜厚度的增加,薄膜的平均晶粒尺寸变大,织构度增强,Cu薄膜的电结晶生长遵循外延生长、过渡生长和完全电沉积条件控制生长；在低电流密度(0.2A／dm2)和较高电流密度(3.5-5.5A／dm2)下,电沉积Cu膜分别容易得到(111)和(220)面择优取向。
Driven by the rapid development of the miniaturization of electronic products and LCD electronic products, application market of COF (Chip on Flex) has been expanding rapidly. As an important part of one of the COF, Flexible substrate of COF Carrying IC chips, circuit the role of connectivity, insulation support. High fine lines, high precision and install lead and 2L-FCCL are the three characteristics. There has been three main methods of preparation of 2L-FCCL, such as coating, laminating and sputtering/plating method.
In this paper, we use magnetron sputtering and sputtering-electro deposition. We make PI-Cu by magnetron sputtering deposited Cu on PI film surface directly, or first make PI-Cu by magnetron sputtering deposited Cu on PI film surface and increase thickness of Cu after Preparation of PI-Cu film. We have been studied the resistivity, preferred orientation, adhesion, surface topography and other properties of PI-Cu produced at different conditions affected by sputtering current, working pressure, electric current density, deposition time, transition preparation process of the film by using XRD, SEM and AFM methods. The results revealed that, the film resistivity of PI-Cu prepared by magnetron sputtering at the preparation conditions which working pressure is 0.4Pa, the smaller the work of the current (less than 10A), Cu film resistivity larger, higher operating current (greater than 12A), The film resistivity smaller, and with the increase of operating current, resistivity changes gradually smaller. Compared with the resistivity of the sample having no transition, Applied transition layer (nickel, titanium nitride, titanium dioxide), the resistivity of the PI-Cu has a greater reduction and the Cu diffraction peaks of the sample increased slightly. Imposed nickel or titanium nitride transition layer, the film resistivity is 35% of the resistivity of the sample without transition layer. Compared with the resistivity of the sample having no transition, Cu thin film adhesion with the transition of nickel or titanium nitride increases four times more. The thicker the thickness of PI-Cu prepared by sputtering-electro deposition, Cu film resistivity smaller, and the resistivity is gradually stability when thickness of Cu is more than 2um, and square resistance is smaller than 0.02Ωand resistivity is smaller than 3.7μΩ×cm. At the condition of the same current density, with the increase of Cu film thickness, the average grain size becomes larger gradually, and the texture degrees. The electricity crystallization growth of Cu film follows epitaxial growth, transition growth and completely electrodeposition condition control growth. The surface morphology of the electro-deposits with (220) and (111) texture separately were obtained at high current density (3.5～5.5A/dm2) and very little current density (about 0.2 A/dm2).
本文采用磁控溅射法与磁控溅射电沉积法,通过在PI膜表面上直接溅射沉积Cu膜或先在PI膜表面上磁控溅射一层导电膜层后通过电沉积加厚的方法制备PI-Cu膜,利用四探针测试仪、X射线衍射仪(XRD)、扫描电镜(SEM)、原子力显微镜(AFM)等手段研究了溅射电流、工作压强、电沉积电流密度、沉积时间、过渡层等制备工艺对薄膜的电阻率、晶面择优取向、附着力、表面形貌等性能的影响。研究表明,采用磁控溅射法制备PI-Cu膜时,工作压强为0.4Pa时,较小的工作电流(小于10A),Cu膜电阻率较大,较大的工作电流(大于12A),薄膜电阻率较小,并且随着工作电流的增大,电阻率变化逐渐变小；与未施加过渡层样品的电阻率相比,施加过渡层(镍、氮化钛、二氧化钛)后,样品的薄膜电阻率有较大的降低、样品的Cu衍射峰有略微增强。施加镍或氮化钛过渡层后,薄膜电阻率比未施加过渡层样品电阻率降低值超过35%；施加镍和氮化钛过渡层后,Cu薄膜剥离强度比未施加过渡层Cu薄膜样品剥离强度大四倍以上。采用磁控溅射-电沉积法制备PI-Cu膜时,薄膜厚度越大,方块电阻和薄膜电阻率越小,薄膜厚度大于2μm时,薄膜的方块电阻与电阻率逐渐趋于稳定,其方块电阻小于0.02Ω,电阻率小于3.7μΩ×cm；相同电流密度下,随着电沉积Cu薄膜厚度的增加,薄膜的平均晶粒尺寸变大,织构度增强,Cu薄膜的电结晶生长遵循外延生长、过渡生长和完全电沉积条件控制生长；在低电流密度(0.2A／dm2)和较高电流密度(3.5-5.5A／dm2)下,电沉积Cu膜分别容易得到(111)和(220)面择优取向。
Driven by the rapid development of the miniaturization of electronic products and LCD electronic products, application market of COF (Chip on Flex) has been expanding rapidly. As an important part of one of the COF, Flexible substrate of COF Carrying IC chips, circuit the role of connectivity, insulation support. High fine lines, high precision and install lead and 2L-FCCL are the three characteristics. There has been three main methods of preparation of 2L-FCCL, such as coating, laminating and sputtering/plating method.
In this paper, we use magnetron sputtering and sputtering-electro deposition. We make PI-Cu by magnetron sputtering deposited Cu on PI film surface directly, or first make PI-Cu by magnetron sputtering deposited Cu on PI film surface and increase thickness of Cu after Preparation of PI-Cu film. We have been studied the resistivity, preferred orientation, adhesion, surface topography and other properties of PI-Cu produced at different conditions affected by sputtering current, working pressure, electric current density, deposition time, transition preparation process of the film by using XRD, SEM and AFM methods. The results revealed that, the film resistivity of PI-Cu prepared by magnetron sputtering at the preparation conditions which working pressure is 0.4Pa, the smaller the work of the current (less than 10A), Cu film resistivity larger, higher operating current (greater than 12A), The film resistivity smaller, and with the increase of operating current, resistivity changes gradually smaller. Compared with the resistivity of the sample having no transition, Applied transition layer (nickel, titanium nitride, titanium dioxide), the resistivity of the PI-Cu has a greater reduction and the Cu diffraction peaks of the sample increased slightly. Imposed nickel or titanium nitride transition layer, the film resistivity is 35% of the resistivity of the sample without transition layer. Compared with the resistivity of the sample having no transition, Cu thin film adhesion with the transition of nickel or titanium nitride increases four times more. The thicker the thickness of PI-Cu prepared by sputtering-electro deposition, Cu film resistivity smaller, and the resistivity is gradually stability when thickness of Cu is more than 2um, and square resistance is smaller than 0.02Ωand resistivity is smaller than 3.7μΩ×cm. At the condition of the same current density, with the increase of Cu film thickness, the average grain size becomes larger gradually, and the texture degrees. The electricity crystallization growth of Cu film follows epitaxial growth, transition growth and completely electrodeposition condition control growth. The surface morphology of the electro-deposits with (220) and (111) texture separately were obtained at high current density (3.5～5.5A/dm2) and very little current density (about 0.2 A/dm2).
引文
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[2]黄惠忠.纳米材料分析[M].化学工业出版社,2003.
[3]辜敏等.硫酸盐镀铜的研究进展[J].材料保护,2006,(1)：44-47.
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[10]谢致薇,罗广南.阴极电弧沉积TiN薄膜的研究[J].真空科学与技术,1992,12(5)：403-407.
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[2]Jun Sun Eom, Sang Ho Kim. Plasma surface treatment of polyimide for adhesive Cu/80Ni20Cr/PI flexible copper clad laminate [J]. Thin Solid Films,2008,516: 4530-4534.
[3]辜信实.挠性覆铜板[J].印制电路信息,2004,(4)：29-33.
[4]辜信实,佘乃东.二层挠性覆铜板[J].印制电路信息,2008,(4)：24-26.
[5]辜信实.用于挠性覆铜板的聚酰亚胺[J].印制电路信息,2004,(4)：17-20.
[6]辜信实.挠性覆铜板技术发展[J].印制电路信息,2007,(9)：7-8.
[7]李小兰,王金龙,严小雄.聚酰亚胺薄膜／超薄铜箔挠性覆铜板的研制[J].绝缘材料,2004,37(1)：14-17.
[8]张晶波等.聚酰亚胺／氧化硅／氧化铝纳米复合薄膜的制备及性能研究[J].绝缘材料,2005,38(1)：9-11.
[9]祝大同.对PCB基板材料重大发明案例经纬和思路的浅析[J].印制电路信息,2007,(3)：2-3.
[10]辜信实.挠性覆铜板用涂布机[J].印制电路信息,2004,(10)：36-38.
[11]余德超,谈定生.电镀铜技术在电子材料中的应用[J].电镀与涂饰,2007,26(2)：43-47.
[12]杨培发,严辉,范和平.二层柔性覆铜板用聚酰亚胺研究进展[J].绝缘材料,2006,39(3)：27-31.
[13]杨邦朝,顾永莲.新型挠性印制电路板基材[J].印制电路信息,2004,(10)：40-41.
[14]刘生鹏.浅述二层挠性覆铜板的进展及市场分布[J].印制电路信息,2007,(5)：2-3.
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[17]祝大同.挠性PCB用基板材料的新发展[J].印制电路信息,2005,(4)：19-29.
[18]刘生鹏,茹敬宏,梁立.LCP在挠性覆铜板中的应用进展[J].印制电路信息,2008,(11)：26-28.
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[1]赵永赞,赵民,王军.聚光器薄膜附着力机理与制备工艺的探讨[J].真空,2002(3)：47-49.
[1]吴自勤,王兵.薄膜生长[M].科学出版社,2001.
[2]黄惠忠.纳米材料分析[M].化学工业出版社,2003.
[3]辜敏等.硫酸盐镀铜的研究进展[J].材料保护,2006,(1)：44-47.
[4]王鸿博.非织造基纳米银薄膜的制备及性能研究[D].51-53.
[1]陈国平.薄膜技术[M].南京：东南大学出版社.
[2]潘永强,卢进军.光学塑料真空镀膜附着力机理与工艺研究[J].应用光学,2003,24(3)：32-34.
[3]李颜霞.塑料真空镀膜[M].北京：化学工业出版社,1990.
[4]唐晋发,顾培夫.现代光学薄膜技术[M].杭州：浙江大学出版社,2006.
[5]腾林等.金属薄膜附着性的改进[J].电子元件与材料,2003,6：41-44.
[6]唐伟忠.薄膜制备材料制备原理、技术及应用[M].北京：冶金工业出版社,2002.
[7]赵永赞,赵民,王军.聚光器薄膜附着力机理与制备工艺的探讨[J].真空,2002(3)：47-49.
[8]Higginbotham IG, Williams R H, Mcevoy A J. Metal/non-metal interfaces: adhesion of gold on mica [J]. J Appl Phys,1975,46(8):1033-1043.
[9]谢致薇,蒙继龙.物理气相沉积薄膜的界面与附着力[J].真空科学与技术,2001,21(3)：203-209.
[10]谢致薇,罗广南.阴极电弧沉积TiN薄膜的研究[J].真空科学与技术,1992,12(5)：403-407.
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