Somekh S, Casey H C
Appl Opt. 1977 Jan 1;16(1):126-36. doi: 10.1364/AO.16.000126.
The properties of ion-beam milling, rf-sputter etching, and plasma etching for the fabrication of high resolution integrated optical structures in GaAs and Al(x)Ga(l-x)As were investigated. The ion-beam milling rates for a 500-eV Ar beam were measured as a function of the angle of incidence for A2-1350 photoresist, GaAs, Al, Ti, and Ta in vacuum. For Ti and Ta, the ion-beam milling rates were measured for various O(2) partial pressures in the target chamber. For the fabrication of high-resolution patterns, a technique was developed in which a very thin resist pattern is transferred by plasma etching into a layer of Ta prior to ion-beam milling. Both ion-beam milling and rf-sputter etching through the Ta metal mask were used for the fabrication of gratings in GaAs. From measurements made in this study, it was found that rf-sputter etching in an Ar atmosphere results in a resolution comparable to ion-beam milling at normal incidence, but the material removal efficiency is somewhat lower. Third-order Bragg diffraction gratings (period = 0.36-0.37 microm) for GaAs-Al(x)Gal(1-x) As heterostructure lasers and ridged stripes 10 microm wide and 1.5-2.0 microm deep have been prepared by these techniques. High-aspect ratio or skewed-profile gratings were obtained by selection of the ion-beam milling or rf-sputter etching conditions. As previously reported, these structures have been overgrown by MBE A(x)Gal(1-x) As layers to form distributed feedback lasers.
研究了离子束铣削、射频溅射蚀刻和等离子体蚀刻在GaAs和Al(x)Ga(l - x)As中制造高分辨率集成光学结构的特性。测量了500 eV氩离子束在真空中对A2 - 1350光刻胶、GaAs、Al、Ti和Ta的离子束铣削速率与入射角的函数关系。对于Ti和Ta，测量了靶室中不同氧气分压下的离子束铣削速率。为了制造高分辨率图案，开发了一种技术，即在离子束铣削之前，通过等离子体蚀刻将非常薄的光刻胶图案转移到Ta层中。通过Ta金属掩膜进行离子束铣削和射频溅射蚀刻都用于在GaAs中制造光栅。从本研究的测量结果发现，在氩气氛中进行射频溅射蚀刻，其分辨率与垂直入射时的离子束铣削相当，但材料去除效率略低。通过这些技术制备了用于GaAs - Al(x)Gal(1 - x)As异质结构激光器的三阶布拉格衍射光栅（周期 = 0.36 - 0.37微米）以及宽10微米、深1.5 - 2.0微米的脊形条纹。通过选择离子束铣削或射频溅射蚀刻条件获得了高纵横比或倾斜轮廓的光栅。如先前报道的那样，这些结构已通过分子束外延生长A(x)Gal(1 - x)As层形成分布反馈激光器。
