Microscale Stacked Wafer Temperature Distribution In The Laser Annealing Process

With the vigorous development of the semiconductor industry,the size of the complementary metal oxide semiconductor components continue to microfilm,and requirements for rapid thermal annealing process are increasingly demanding.In the laser spike anneal process,"pattern effect" due to the wafer surface pattern of the laser spike anneal process,will result in non-uniform temperature distribution in the wafer,excess thermal stress and crystal defects,which led to transistor electrical performance variation,which is one of the important issues currently for nanometer semiconductor.Based on this,the paper carried a simulation on different stack wafer in a carbon dioxide laser spike annealing temperature distribution to optimize the wafer laser annealing process,provide theoretical support for eliminating the "pattern effect".First of all,based on the software Rad-Pro,the paper calculated the surface radiation properties(absorptivity and reflectivity)of five different stack structure.On this basis,the carbon dioxide laser thermal radiation stack wafer heat transfer mathematical model is established by using COMSOL software solid heat transfer module,and studied the temperature distribution of the different stack type of wafer under different laser power and heating time.Giving the following conclusions:(1)The absorbance value of different stack structure on the wafer surface.Stack 1(silicon):the absorption rate is stable at around 0.683;Stack 2(silicon/polysilicon):the initial value of the absorption rate is 0.676.The absorption rate decreased to 0.528 with the temperature increase.Stack 3(silicon/polysilicon/silicon dioxide):the initial value of absorption rate is 0.747.With the increase of temperature,absorption rate decreases to the final value of 0.542.Stack 4(silicon/polysilicon/silicon dioxide/silicon nitride):the initial value of the absorption rate is 0.752.With the temperature increases,the absorption rate decreases to 0.546.Stack 5(silicon/polysilicon/silicon nitride):the initial value of absorption rate is 0.675.With the increase of temperature,absorption rate continues to decrease,the minimum value is 0.531.(2)The effects of laser power and heating time on temperature distribution of the stack wafer surface.Stack 2:when the heating time is a constant,peak temperature gradually increased as laser power increased.Energy is gathered on the surface and the trend of spreading to the surrounding is not obvious.When the power is a constant,temperature gradually spread to the surrounding with increasing the heating time.With the power is 300W and the time for 1000?s,the maximum peak temperature and minimum vertical isotherms temperature difference occurred.Stack 3,Stack 4 and stack 5 have the similar nature as stack 2.At the same time,when the heating time is a constant,the peak temperature of the 5 stack structures shows linear correlation with the laser power.When the laser power is a constant,the peak temperature of the 5 stack structures shows the parabolic correlation with the heating time.