{"title":"用于倒装芯片中碰撞冶金薄膜下选择性蚀刻的喷酸工具的特性","authors":"L. Ramanathan, D. Mitchell","doi":"10.1109/IEMT.2003.1225919","DOIUrl":null,"url":null,"abstract":"A methodology for optimizing and characterizing processes for selectively etching Cu underbump metallurgy in the presence of Pb-Sn solder in spray acid tools is discussed. Wafers with the following UBM and bump structure were used in this study: sputtered TiW/sputtered Cu/electroplated Cu stud/electroplated Pb-Sn solder. The development of a manufacturable etch process is illustrated by discussing the method used to establish the process for selectively etching the sputtered Cu film using a commercial, two-component, ammoniacal Cu etch chemistry. The average etch rate on monitors with blanket sputtered Cu films, placed in all slots of the tool clamshell, was used to establish a non-uniformity factor (/spl eta/), which is defined as the ratio of the etch rate in the slot displaying the fastest etch rate to the etch rate in the slot displaying the slowest etch rate. Under ideal conditions the non-uniformity factor should be unity. Over the parameter space investigated it was found that the non-uniformity factor was minimized with the following conditions: temperature of 27/spl deg/C, RPM of 20, pump pressure of 52 psi, etchant flow rate of 6 liters/min, and a 25% solution of the two-component etch chemistry, with the two-components in a 1:3 proportion. Flip chip packages containing electroplated Cu stud and solder bump structures require selective etching of the underlying underbump metallurgy layers that serve as a diffusion barrier and as an electrical bus layer for the electroplating process. In this paper the characterization of a spray acid tool for selectively etching the sputtered Cu bus layer from multiple wafers simultaneously is discussed. The use of the non-uniformity parameter, /spl eta/, defined earlier, to establish the preliminary process is presented. /spl eta/ was also used to understand the parameters that controlled the uniformity of the spray pattern. In particular the effect of pump pressure, flow rate, and etchant composition on /spl eta/ was used to establish the levels of these variables for the Cu etch process. The preliminary Cu etch process was confirmed with a full lot containing 25 blanket Cu wafers. A maximum overetch of 39% was obtained for the full lot.","PeriodicalId":106415,"journal":{"name":"IEEE/CPMT/SEMI 28th International Electronics Manufacturing Technology Symposium, 2003. 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The development of a manufacturable etch process is illustrated by discussing the method used to establish the process for selectively etching the sputtered Cu film using a commercial, two-component, ammoniacal Cu etch chemistry. The average etch rate on monitors with blanket sputtered Cu films, placed in all slots of the tool clamshell, was used to establish a non-uniformity factor (/spl eta/), which is defined as the ratio of the etch rate in the slot displaying the fastest etch rate to the etch rate in the slot displaying the slowest etch rate. Under ideal conditions the non-uniformity factor should be unity. Over the parameter space investigated it was found that the non-uniformity factor was minimized with the following conditions: temperature of 27/spl deg/C, RPM of 20, pump pressure of 52 psi, etchant flow rate of 6 liters/min, and a 25% solution of the two-component etch chemistry, with the two-components in a 1:3 proportion. Flip chip packages containing electroplated Cu stud and solder bump structures require selective etching of the underlying underbump metallurgy layers that serve as a diffusion barrier and as an electrical bus layer for the electroplating process. In this paper the characterization of a spray acid tool for selectively etching the sputtered Cu bus layer from multiple wafers simultaneously is discussed. The use of the non-uniformity parameter, /spl eta/, defined earlier, to establish the preliminary process is presented. /spl eta/ was also used to understand the parameters that controlled the uniformity of the spray pattern. In particular the effect of pump pressure, flow rate, and etchant composition on /spl eta/ was used to establish the levels of these variables for the Cu etch process. The preliminary Cu etch process was confirmed with a full lot containing 25 blanket Cu wafers. 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引用次数: 0
摘要
讨论了在铅锡焊料存在的情况下,在喷雾酸工具中选择性蚀刻铜的工艺优化和表征方法。本研究使用的晶圆具有以下两种结构:溅射TiW/溅射Cu/电镀Cu螺柱/电镀Pb-Sn焊料。通过讨论利用商业的、双组分的、氨化的Cu蚀刻化学方法来建立选择性蚀刻溅射Cu薄膜的工艺,说明了可制造蚀刻工艺的发展。平均腐蚀速率监控与毯子气急败坏的铜电影,放置在所有插槽翻盖的工具,被用来建立一个不均匀性因素(spl eta /),它被定义为槽的腐蚀率的比率显示最快的腐蚀率的腐蚀率槽显示腐蚀速率最慢。在理想条件下,非均匀性系数应为1。通过对参数空间的研究,发现在以下条件下,非均匀性因素最小:温度为27/spl℃,转速为20,泵压力为52 psi,蚀刻剂流量为6升/分钟,25%的双组分蚀刻化学溶液,两组分的比例为1:3。包含电镀铜螺柱和凸点结构的倒装芯片封装需要选择性地蚀刻凸点下的冶金层,这些层作为扩散屏障和电镀过程的电气总线层。本文讨论了一种可同时选择性蚀刻多片溅射铜母线层的喷酸工具的特性。不均匀的使用参数,spl eta /,前面定义,建立初步的过程。/spl eta/也用于了解控制喷雾图案均匀性的参数。特别是泵压力、流量和蚀刻剂成分对/spl / eta/的影响,用于建立Cu蚀刻过程中这些变量的水平。初步的铜蚀刻工艺被确认为含有25个包层铜晶片的完整批次。整个批次的最大复刻率为39%。
Characterization of a spray acid tool for selectively etching under bump metallurgy films used in flip chip applications
A methodology for optimizing and characterizing processes for selectively etching Cu underbump metallurgy in the presence of Pb-Sn solder in spray acid tools is discussed. Wafers with the following UBM and bump structure were used in this study: sputtered TiW/sputtered Cu/electroplated Cu stud/electroplated Pb-Sn solder. The development of a manufacturable etch process is illustrated by discussing the method used to establish the process for selectively etching the sputtered Cu film using a commercial, two-component, ammoniacal Cu etch chemistry. The average etch rate on monitors with blanket sputtered Cu films, placed in all slots of the tool clamshell, was used to establish a non-uniformity factor (/spl eta/), which is defined as the ratio of the etch rate in the slot displaying the fastest etch rate to the etch rate in the slot displaying the slowest etch rate. Under ideal conditions the non-uniformity factor should be unity. Over the parameter space investigated it was found that the non-uniformity factor was minimized with the following conditions: temperature of 27/spl deg/C, RPM of 20, pump pressure of 52 psi, etchant flow rate of 6 liters/min, and a 25% solution of the two-component etch chemistry, with the two-components in a 1:3 proportion. Flip chip packages containing electroplated Cu stud and solder bump structures require selective etching of the underlying underbump metallurgy layers that serve as a diffusion barrier and as an electrical bus layer for the electroplating process. In this paper the characterization of a spray acid tool for selectively etching the sputtered Cu bus layer from multiple wafers simultaneously is discussed. The use of the non-uniformity parameter, /spl eta/, defined earlier, to establish the preliminary process is presented. /spl eta/ was also used to understand the parameters that controlled the uniformity of the spray pattern. In particular the effect of pump pressure, flow rate, and etchant composition on /spl eta/ was used to establish the levels of these variables for the Cu etch process. The preliminary Cu etch process was confirmed with a full lot containing 25 blanket Cu wafers. A maximum overetch of 39% was obtained for the full lot.