Research On Micro Wear And Corrosion Damage Behavior Of GeSbTe Phase Change Memory Materials

Phase change memory is known as the next generation non-volatile memory due to its high storage density,fast read / write speed,and strong corrosion resistance.During the preparation of the phase change memory,a CMP(Chemical Mechanical Polishing)process is required to remove the excess GeSbTe material on the surface of the storage structure.Therefore,in order to promote the development of GeSbTe phase change memory,it is urgent to study the CMP removal mechanism of GeSbTe materials.The traditional method to study the mechanism of CMP removal is CMP experiment,but it is not easy to reveal the mechanism of CMP removal because of multi abrasive.This article uses the atomic force microscope probe and NaOH solution to microscopically remove the GeSbTe material and explores its mechanism.Firstly,the environmentally controlled atomic force microscope was used to explore the microscopic wear in the atmospheric environment.The results show that the greater the load,the more severe the wear on the GeSbTe Surface and the rate of wear gradually decreases with increasing time.It can be seen from the experiment of the wear under the atmosphere and pure nitrogen that the wear process in the atmospheric environment is dominated by mechanical action.The wear mechanism of GeSbTe in atmospheric environment is revealed by calculating the shear stress and dissipation energy in the wear process.Further experiments show that the main reason for the slowing of the wear rate of GeSbTe at the later stage of wear in the atmospheric environment is the lubrication effect of abrasive debris in the wear.Therefore,in the atmospheric environment,the wear has gone through the following stages: 1.The initial stage of wear,during which the wear is more serious and accompanied by the generation of wear debris;2.In the stable stage of wear,the wear debris plays a lubricating role on the contact surface of the friction pair,making the wear gradually slow down.Secondly,the microwear-corrosion experiment of GeSbTe material based on NaOH solution was carried out.According to the corrosion experiment of the natural oxide layer on the surface of GeSbTe,the corrosion of the natural oxide layer on the surface of GeSbTe in NaOH solution(pH = 11)is negligible,so it can play a masking role in the corrosion experiment.However,the experiment of first wear and then corrosion in atmospheric environment shows that the mechanical action before wear can promote corrosion,and the depth of wear will increase with the increase of corrosion time.Finally,in order to simulate the micro-damage(material removal)process of GeSbTe in the actual CMP process,the wear experiment in NaOH solution was carried out.The results show that the micro-wear of GeSbTe in NaOH solution will still occur.Comparing the wear depth of GeSbTe surface under the above two different working conditions,it can be seen that the damage of GeSbTe in NaOH solution is slighter than in atmospheric environment.Further analysis reveals that the micro-damage behavior of GeSbTe in NaOH solution is affected by the liquid lubrication and double electron layer,which leads to the natural oxide layer more difficult to destroy than in the atmospheric environment.Since the ability to remove the natural oxide layer on the surface of GeSbTe is different under the two working conditions,and the natural oxide layer can act as a mask in the NaOH solution.So it leads to changes in subsequent corrosion.This paper studies the microscopic wear and corrosion damage behavior of GeSbTe materials,and reveals the microscopic wear mechanism and corrosion damage rules of GeSbTe materials in the atmosphere.The above conclusions can better understand the material removal mechanism of GeSbTe phase change materials in CMP.