Mechanism And Application Of Accelerator Of Copper Electroplating In Electronic Interconnection

With the development of electronic products in the direction of miniaturization,thinning and high performance,higher requirements are put forward for electronic interconnection and electronic packaging.Acidic copper sulfate electroplating has high plating solution stability and high current efficiency,and is the best solution for manufacturing chips,packaging substrates,printed circuit boards and other devices in the electronics industry.Sodium polydithiodipropane sulfonate（SPS）,sodium 3-mercapto-1-propane sulfonate（MPS）and derivatives of MPS are commonly used accelerators in electroplating copper.In the actual industrial production,the accelerator is the most significant influence in the plating solution,but it is also the component with the lowest concentration and the largest fluctuation.Most of the performance degradation of the plating solution is caused by the imbalance of the concentration of the accelerator.Studying the action mechanism of accelerators and exploring the structure-activity relationship of new accelerators are of great significance for controlling the stability of the electronic interconnection manufacturing process and realizing high-quality electronic packaging.Thesis focuses on the mechanism of action of the accelerator SPS,and synthesizes the real"accelerating substance"copper mercaptopropanesulfonate（MA）in the process of SPS action.After exploring its molecular structure by characterization test method,a mechanism of accelerator action was proposed.the electrochemical characteristics of MA were studied by electrochemical method,the role of MA in electroplating was analyzed,and the applicable concentration of MA and its application in actual electroplating were tested by electroplating on the test plate.Research:Firstly,the target compound MA was prepared with SPS and MPS as initial materials,cuprous oxide as monovalent copper source,and copper oxide as divalent copper source,respectively.The molecules of MA were identified by scanning electron microscopy（SEM）,ultraviolet-visible absorption spectroscopy（UV）,Raman spectroscopy（Raman）,X-ray photoelectron spectroscopy（XPS）,and gas-liquid mass spectrometry（HPLC-MS）.structure.Then,the electrochemical properties of MA were studied by means of galvanostatic（GM）test,cyclic voltammetry（CV）test and galvanostatic step（CA）test.to the accelerating effect.And there is a good linear relationship between 100μg L^-1 and 1 mg L^-1.When the concentration of the accelerator increases to above 1.5 mg L^-1,the relationship between the concentration of MA and the amount of deposited copper can be expressed by an exponential equation.Precise monitoring of MA concentration in the bath prevents performance degradation of the bath.Finally,the application prospect of MA in different scenarios is discussed.When the concentration of MA is between 0.4 mg L^-1 and 1.2 mg L^-1,a uniform and bright coating can be obtained from the plating solution.Compared with SPS,the microscopic morphology of these coatings did not change significantly.The TP value can reach 83.8%in through-hole plating with a thickness-to-diameter ratio of 10:1,and MA ranges from0.6 mg L^-1 to 1.3 mg L^-1 in blind hole plate filling with a hole diameter of 150μm and a hole depth of 50μm.The concentration range of 1 can achieve better filling effect,and the best Dimple is as low as 3μm.