ECCP干法刻蚀条件下的TFT基板绝缘层过孔腐蚀的改善

过孔搭接失效一直是TFT-LCD行业中重点改善的不良之一。为了解决该不良,本文分析了不同刻蚀模式(ICP和ECCP)对过孔形貌的影响,利用四因子法研究ECCP模式刻蚀参数(压力、偏置/源极射频功率及O_2/SF_6气体比例)对刻蚀速率和均一性的影响,并得出ECCP过孔改善的最佳刻蚀参数。结果表明:ECCP模式下,氮化硅刻蚀过程中物理轰击对GI截面的下沿与Cu接触区域形成损伤后产生的缺陷,是诱发过孔腐蚀的主要因素,ICP模式无腐蚀。反应腔压力增大刻蚀速率增大,均一性下降;偏置射频功率增大,速率增大,均一性提高;源极射频功率增大,速率变化小,均一性下降;O_2/SF_6气体比例对速率影响小,O_2含量越高,均一性越高。为达到PR胶保护GI下沿截面的目的,反应压力增大到1.7Pa,偏置射频功率减小到30kW,源极功率增加到30kW,O_2/SF_6气体保持比例1∶1后,增加了氮化硅的刻蚀量,减小PR胶的内缩量,避免物理溅射表面损伤;同时刻蚀速率达到750nm/s,均一性达到10%,腐蚀发生率为10%～0,使ECCP刻蚀模式对过孔的腐蚀影响得到有效解决。

Improvement of via-hole corrosion in TFT substrate insulation under ECCP dry etching condition

The invalidation of via-hole connect is one of the major issues in TFT-LCD industry. To solve out this issue, the influence of different via-hole etch mode (ICP and ECCP) was analyzed; the effects of ECCP mode etching parameters (chamber pressure, bias/source RF power and O₂/SF₆ gas ratio) on the etching rate and homogeneity were investigated by the four factor method, and the optimum etching parameters of the ECCP over hole improvement were obtained. The results show that the physical bombardment in the etching process of silicon nitride under the ECCP mode is the main factor to induce the corrosion of the pores in the lower edge of the GI section and the contact area of the Cu, which doesn't happen under ICP mode. The etch rate increases with the increasing of chamber pressure, and the uniformity decreases. The rate increases with the in creasing of source and bias power, the uniformity increases with source power and decreases with bias power. The impact of ratio gas (O₂/SF₆) on etching rate is very small, and the higher the O₂ content, the better the homogeneity. In order to achieve the purpose of protecting the lower section of GI with photoresist (PR), the reaction pressure is increased to 1.7 Pa, the bias RF power is reduced by 30 kW,the source RF power is increased by 30 kW and the O₂/SF₆ gas is kept to 1:1, which increase the etching amount of silicon nitride, and the internal shrinkage of the PR glue is reduced, which avoid the surface damage of the sputtering. Under this etching parameters, the etching rate is 750 nm/s, the uniformity is 10%, and the corrosion rate is from 10% to 0. The corrosion of the via-hole under ECCP etching mode is solved effectively.