Research On Transfer Technology And Device Application For Heterogeneous Integration

In the past few decades,under the guidance of Moore's Law in the semiconductor industry,the minimum size of silicon-based devices has gradually decreased,and circuit performance and computing speed have gradually increased.However,due to the limitations of the physical properties of semiconductor silicon materials,in the foreseeable future,the size of silicon-based devices has been unable to meet the laws of Moore's Law and continues to shrink.Because single-crystal silicon nano-films have unique physical and chemical properties that are different from silicon bulk materials,compound semiconductors represented by Ga N materials have higher breakdown voltage,electron mobility and other advantages.It is extremely urgent to integrate single crystal silicon thin film devices with compound semiconductor devices to meet the development requirements of ultra-miniaturization,intelligence,and diversification of electronic systems.At present,this heterogeneous integration technology has been gradually applied to 5G wireless applications,sensors and millimeter waves and other fields.There have been many mature methods for the development of heterogeneous integration technology to the current stage,such as epitaxial growth,bonding,three-dimensional packaging,and transfer printing.The main research direction of this paper is the transfer technology in the heterogeneous integration technology,and based on the transfer technology,the preparation method of monolithic heterogeneous integrated monocrystalline silicon thin film and Ga N device is proposed.The detailed investigation are as follows:It is found that during the transfer process,the experiment often encountered the problem of incomplete etching of the sacrificial layer.Therefore,through the analysis of the principle of wet etching of the sacrificial layer,it is found that the double-electron layer effect and van der Waals force have an important influence in the process of etching the sacrificial layer.The factors that may affect the incomplete etching of the sacrificial layer: hydrofluoric acid concentration,etching temperature,sacrificial layer pattern size,positioning anchor point position,sacrificial layer pattern shape,and sacrificial layer thickness are compared and studied.And based on the concept of pull-up length quantified the requirements of the device size for the complete etching of the sacrificial layer.At the same time,in order to complete the complete etching of the sacrificial layer,the selection range of the above factors is summarized,Finally,an idea of improving the etching effect of the sacrificial layer with a wider application range is proposed.With the deepening of the research on the transfer process at home and abroad,various transfer methods have emerged.This article mainly conducts a comparative study on the two most commonly used transfer methods in laboratories: the controlled separation speed method and the tape transfer method.Through comparative experiments,the differences between the two transfer methods in terms of transfer efficiency,yield,cleanliness and operability were obtained.Finally,the pyro-release tape transfer method was used to replace the control separation speed method for the preparation of monolithic heterogeneous integrated monocrystalline silicon films and Ga N devices based on the transfer technology,which increased the transfer yield from32.5% to 97.3%.In this paper,combined with the transfer technology in heterogeneous integration,based on the research of sacrificial layer etching and transfer method,a preparation method of monocrystalline silicon thin film device and Ga N device monolithic heterogeneous integration is proposed.The Si MOSFET device and Ga N HEMT device on a heterogeneous integrated monolith were tested,and it was found that the performance of the device was not significantly degraded,which proved the feasibility of the transfer method for preparing monolithic heterogeneous integrated devices.