Electrochemical Wet Process To Fabricate SiO₂ Insulation Layer And Its Application

Miniaturization and high integration are the main driving forces for the future development of electronic packaging technology in the direction of three-dimensional stacking,and Through Silicon Via(TSV),which is the main key technology,is also moving towards the goal of smaller apertures and larger aspect ratios.However,the fabrication of the insulation layer,which is the key process of TSV,has encountered bottlenecks such as low retention,poor film formation quality,or low growth rate in traditional methods.At the same time,in the face of the everexpanding requirements of low-temperature and even-temperature manufacturing,it is even more urgent to explore an extra way to prepare a high-profile insulation layer in a large aspect ratio TSV at low temperature.Based on this,this paper explores two processes of one-step oxidation method and porous silicon precursor oxidation method to prepare TSV silicon dioxide insulating layer based on wet anodization.The argument of porous silicon layer controlling oxidation depth is demonstrated.The properties and applications of the oxide films prepared by these two methods are systematically discussed.The research content of this paper is mainly divided into the following two parts:In the first part,the thickness,micro-morphology,macro-resistance change,and surface bonding of the one-step method and the porous silicon precursor oxidation method under different process parameters were studied.The study found that the lower the resistance is,the stronger the electrical field will be;the increase of the oxidation voltage will increase the surface roughness and thickness of the oxide layer.When the voltage or oxidation time exceeds a certain limit,there will be obvious Si-O antisymmetrical stretching vibration peaks on the infrared spectrum;For porous silicon layers,the research found that when the reaction energy provided by the external electric field strength is higher than the reaction energy barrier of the porous silicon layer and lower than the reaction energy barrier of the silicon substrate,the oxidation reaction will only occur in the porous silicon layer,thereby achieving a precise control of oxidation layer thickness.In the breakdown voltage test,it was found that the breakdown field strength of the oxide layer prepared at different voltages decreased with the increase of the voltage in the one-step method,and the sample with the thickness of the oxide layer controlled by the porous silicon layer had a higher breakdown field strength as the oxidation voltage increases,and the leakage current also decreases.Samples from both methods passed the scribe type test and showed good adhesion to the substrate.In the second part,two types of TSVs with different resistivities and aspect ratios were successfully prepared on the two TSVs by changing the oxidation voltage,electrolyte concentration,and oxidation time.The best step coverage as 76.1% and 75.4% can be achieved,respectively.The research had also found the porous structure is conducive to the elimination of air bubbles during the TSV wet oxidation process,to prevent the generation of cracks,has further research and application value.