Structural Design And Process Research Of Silicon-Based Transient Devices With Accelerated Strain Degradation

Transient electronic device,without affecting the original function,refers to a new type of electronic device in which the prepared device partially or completely disappears at a certain rate in a short time after receiving the external signal.As an emerging electronic device,it has developed rapidly in recent years in the fields of information security and biomedicine.At present,most of the transient electronic devices are water-degradable.Since traditional electronic materials are not fully applicable,transient electronic devices mainly use some degradable new substrate materials and degradable metal electrodes.Because of the stable and inactive nature of semiconductor crystal materials such as silicon,germanium,gallium nitride,and silicon carbide,it takes several days or even more than a week for the device to be completely degraded.In view of the long degradation time of transient devices,this paper proposes to increase the contact area between the chip and the solution to accelerate the degradation rate of the device.According to the fact that single crystal silicon is a brittle material and is easily broken,the implementation measures are to introduce stress into the device to strain or even break the chip to accelerate the degradation rate of the silicon-based transient device.The traditional method of introducing stress into the device is to grow the different materials by the process to cause the lattice mismatch to cause strain.However,the stress generated by this method is not enough to achieve the breaking strength of the chip,and the large stress must be introduced in other ways,filling the expandable material.Since the hydrogel,formed by the super absorbent polymer sufficiently absorbing water,can be expanded to several hundred or even thousands of times its own volume,super absorbent polymer is introduced into the device herein.Based on the standard device package structure,two methods,which are making super absorbent polymer into device,are proposed in this paper: one is to etch the deep groove array on the back side of the chip to fill the water absorbing resin;the other is to machine the groove filling super absorbent polymer on the package tube.Etching deep trenches on the backside of the chip is equivalent to fabricating a type I crack on the silicon wafer,which greatly reduces the breaking strength of the single crystal silicon.In this paper,a deep groove array of 100?m/75?m wide-depth ratio is etched on the back side of a 300?m thick silicon wafer.The experiment was carried out by filling super absorbent polymer to verify the feasibility of the solution.For the method of processing the groove on the package tube,the present invention is based on the ceramic package device,and the premise of the chip fracture under this structure is that the ceramic substrate is broken.Firstly,a series of square groove molds with different volume sizes were fabricated to study the fracture condition of alumina ceramic substrate.For the case where the gel strength of super absorbent polymer is small and the stress is relatively average,this paper places the local stress concentration on super absorbent polymer layer.A layer of hard-edged thin sheets reduces the water-absorbent resin layer to less than 500 ?m,and the minimum volume of the grooves is 5.5 mm*5.5 mm*1.5 mm while ensuring that the fracture time of the ceramic substrate is within three minutes.Then,based on the minimum groove volume,the influencing factors affecting the fracture time of the ceramic substrate,including the influence of the temperature impact test,are explored,and optimized the structure of the groove.Finally,the ceramic package tube is fabricated according to the optimized structure,then making complete device,and the experimental effect is discussed after water triggering.