镍基阵列微针的薄胶微电铸制备工艺

Preparation of Ni microneedle array using thin photoresist microelectroforming technique

阵列镍微针具有机械强度高、导电性好等优点,广泛应用于生物工程等领域。微电铸工艺凭借其复制精度高、适应性广等优点,已成为制备镍微针的可靠方法。然而,在微电铸工艺中,通常需要使用与铸层厚度相同的光刻胶模具,导致厚胶微电铸时面临微结构处存留残胶、胶层难以去除等问题。为了解决上述问题,获得尖端曲率半径为纳米尺度的阵列镍微针,我们提出了镍基阵列微针的薄胶微电铸制备工艺并进行实验验证。首先,利用(100)型单晶硅的各向异性刻蚀特性制备阵列锥坑硅模具;接着,在硅模具表面溅射一层厚度为200 nm的镍种子层;然后,使用光刻工艺制备微针支撑梁薄胶模具;最后,对硅模具进行微电铸,释放阵列镍微针。实验结果表明:本实验采用的方法可以在不损伤硅模具的前提下,得到尺寸平均偏差1.7μm、绝对位置平均偏差1.8μm、尖端平均曲率半径150 nm的阵列镍微针;使用厚度为~2μm的RFJ-60负性光刻胶作为微电铸的模具,成功制备出厚度为~24.3μm的阵列镍微针支撑梁。此外,通过将SiO2侧蚀量补偿进光刻掩膜版图形尺寸的方法,将镍微针相对尺寸误差降低至1%。结合微电铸工艺和单晶硅的各向异性刻蚀特性,能够高质量、高效率地制备阵列镍微针,为阵列镍微针的批量化制备奠定了基础。

With the advantages of high mechanical strength and good electrical conductivity,Ni microneedle arrays are widely used in bioengineering and other fields.By virtue of the advantages of high replication accuracy and wide adaptability,the microelectroforming technique has become a reliable method for preparing Ni microneedles.However,it is usually necessary to use photoresist template with the same thickness as that of the casting layer in the microelectroforming technique.Thick photoresist microelectroforming faces problems such as residual photoresist at the microstructure,difficulty in removing the photoresist.In order to solve the above problems,obtain Ni microneedle arrays with tip curvature radius on the nanometer scale,the fabrication process for Ni microneedle arrays based on the thin photoresist microelectroform ing technique was designed and experimentally verified.First,a silicon template with arrays of pits was fabricated on(100)single crystal silicon wafers.Next,a Ni seed layer with a thickness of 200 nm was sputtered onto the surface of the silicon template.Then,a thin photoresist template of the microneedle support beam was prepared using the photolithography technique.Finally,Ni microneedle arrays were released after microelectroforming.The experimental results show that Ni microneedle arrays with an average deviation in size of 1.7μm,an average deviation in absolute position of 1.8μm,and an average curvature radius of 150 nm at the tip were obtained by this method without damaging the silicon template.Using RFJ-60 negative photoresist as a template for microelectroforming with a thickness of-2μm,microneedle support beams with a thickness of-24.3μm were successfully prepared.Ni microneedle relative dimensional error was reduced to 1%by compensating SiO2 lateral erosion into lithographic mask.Combining the microelectroforming technique and the anisotropic etching property of monocrystalline silicon,the Ni microneedle array can be prepared with high quality and high efficiency,which lays the foundation for the batch preparation of Ni microneedle arrays.