场发射栅孔阵列的制备

Fabrication of gate holes for field emission array

采用硅的局部氧化技术以及湿法刻蚀技术,利用2.6μm的光刻掩模板在n型硅片上形成了栅极孔径为1μm的场发射阴极的栅极空腔阵列,实现了用大阵点尺寸的栅极掩模板制备较小尺寸栅孔阵列。硅的湿法刻蚀溶液采用各向同性的硝酸和氢氟酸混合溶液,刻蚀后空腔的深度和宽度均随刻蚀时间线性增加。同时,由于刻蚀溶液具有较高的Si/SiO2刻蚀选择比,栅极孔径随刻蚀时间增大的速度远低于深度和宽度增大的速度,栅极孔径主要取决于掩模的尺寸和氧化层的厚度。通过选择掩模板的尺寸以及氧化层的厚度,采用局部氧化技术和湿法刻蚀技术能够制备出微米或亚微米的场发射阴极的栅极空腔阵列。

Aperture of gate hole is an important geometry parameter in a Spindt-type field emission array（FEA） cathode. During the local oxidation of silicon（LOCOS） process, a SiO2 ＂bird beak＂ will form and lead to much smaller holes than the Si3N4 dot patterned by lithography. By means of LOCOS and wet etching of the silicon substrate, gate of FEA with 1 μm aperture was fabricated using a photo mask of 2.6μm-dot （designed） array. The etchant composed of nitric acid （65%） and hydrofluoric acid （40%） isotropicly etched the silicon material, resulting in simultaneous growth the depth and width of gate holes. However, the hole aperture gradually enlarged at a rate only 5% of that of the development of the depth. The ultimate hole aperture principally defined by the photo mask size and the thickness of thermal SiO2.