Interfacial adhesion of spin-coated thin adhesive film on silicon substrate for the fabrication of polymer optical waveguide

Abstract

An investigation was carried out to study the interfacial adhesion of spin-coated polymeric adhesive thin film on a silicon substrate for fabrication of a polymeric optical waveguide. An adhesive shear button was made on a silicon substrate by using a photolithography process, and interfacial adhesion was measured with a Dage D2400 shear tester. Different adhesion strengths were found at different portions of the same sample. Higher adhesion strength was observed at the center of the substrate than at other locations of spincoated adhesive films. Adhesion strength was also measured after heat exposure of the deposited and cured adhesive layer to evaluate the heat resistance of the adhesive film. After heat exposure, adhesion strength decreased substantially from all locations of the substrate due to the thermal degradation. Again, the adhesion was measured for different plasma-treated substrate conditions. The surface morphology of plasma-treated and untreated silicon substrates before deposition were characterized by atomic force microscopy. Lower adhesion strength was unexpectedly observed for all plasma-treated substrates, even for higher surface roughness. The fracture surfaces after shear testing were also characterized by optical microscopy. The complete study provides important indications for the fabrication of better-performing polymeric optical waveguides for photonic devices.

Adhesive technology for photonics

“…Even for the same substrate and process condition, different interfacial adhesions were found on different portions of the substrate. 43 However, the differences within the same substrate were not large and therefore the distribution did not show up well. Here, the results present the averages (solid bar) and the full distribution of the data values (36 samples for each bar) of the interfacial adhesion for each corresponding substrate structure with respect to a specific process condition.…”

“…9 Therefore, the most important test for any adhesive is that it should give joints that are strong and durable. Although ways do exist of assessing the quality of joints by ultrasonic non-destructive testing, the ultimate test is to measure the force or energy needed to break the joint.…”

“…However, the adhesion of polymeric adhesives to the silicon surface is comparatively poor. 43 An oxidized silica-containing (thin layer of silica on silicon) silicon wafer can be use as a substrate and is becoming very attractive due to its matching refractive index with optical polymers. Thermal oxidation of silicon is easily achieved by heating the substrate to temperatures typically in the range of 900-1200 o C.…”

“…Therefore, there is a major need for practical as well as scientific information about the proper handling and properties of polymeric materials for the fabrication of reliable photonics products. Recent studies 38,43,53 have focused mainly on proper polymer processing and the fabrication of reliable photonics devices. The challenges are to achieve compatibility with other electro-optic systems and processes, end-use reliability, reproducibility, stability, acceptable performance, and cost, commensurate with added value.…”

The Study of the Effects of Polishing Rotation Speed to the Length of Cut End Face SU-8 Polymer on Silicon Substrate

“…Peranti optik bersepadu berasaskan polimer yang mengandungi elemenelemen pasif dan aktif digunakan dalam pelbagai fungsi gandingan, penghalaan, penurasan dan pensuisan. Kebanyakkan aplikasi pandu gelombang polimer digunakan dalam bidang komunikasi optik (Tamaki et al 2003;Uddin et al 2006;Uddin et al 2009& Francesco et al 2007). Proses pembuatan pandu gelombang polimer lebih mudah dan cepat jika dibandingkan dengan proses bagi menghasilkan pandu gelombang silika.…”