兼容CMOS工艺的Ga2O3辅助GaN-to-Si异质键合技术及机理研究

The industry believes that the future of compound semiconductor electronics depends not on displacing Si, but rather on the heterogeneous integration of compound semiconductor with silicon technology in a way that will allow the combination advantages. Based on this consensus, the top international semiconductor manufacturers have started to implement the diverse accessible heterogeneous integration program towards a next-generation technology platform for high-performance micro-systems, in which CMOS-process-compatible heterogeneous bonding of GaN-to-Si is an important part. Currently, GaN-to-Si bonding solutions are facing new challenges related with CMOS compatible process. The main difficulty lies in : 1 , need to withstand high temperature process (~ 1000 ℃), and be free of pollution risks; 2 , photolithography plane height difference between heterogeneous materials is limited (<1.5μm). This project intends to introduce Ga2O3 as a bonding auxiliary layer for the first time. Through the regulation of the auxiliary layer parameters , surface activation and heat treatment processes, the correlation between the bonding interface characteristics and control parameters is investigated, and the microscopic mechanism of GaN/Ga2O3/Si bonding is revealed, which will give a new idea to realize the CMOS-compatible GaN-to-Si bonding and provide a common technical support and new growth point for the development of new circuits and modules, and further more play a strategic role on bypassing the foreign technical barriers and promoting seamless monolithic functional integration and building the next generation technology platforms for high-performance micro-system.

业界认为化合物半导体的未来不在于代替硅，而在于通过异质集成发挥二者组合优势。基于此共识，国际顶级半导体厂商已着手实施面向下一代高性能微系统技术平台的异质集成项目，其中兼容CMOS工艺的GaN-to-Si异质键合是关键内容之一。当前GaN与Si键合方案面临兼容CMOS工艺的新挑战，其主要难点在于：1、需承受高温工艺（～1000℃），且无污染风险；2、异质材料光刻平面高度差受限（<1.5μm）。本项目拟首次引入Ga2O3作为键合辅助层，通过调控辅助层参数、表面活化和热处理流程，研究键合界面特性与调控参数的相关性，揭示GaN/Ga2O3/Si异质界面键合的微观机理，为实现兼容CMOS工艺的异质键合探索新的思路，进而为新型电路和模块的开发提供共性技术保障及新增长点,这对绕开国外技术壁垒，推动基于完全CMOS工艺线的无缝单片功能集成和打造下一代高性能微系统技术平台具有重要战略意义。

本项目针对兼容CMOS工艺的GaN-to-Si异质键合需求，引入三氧化二镓（Ga2O3）作为键合辅助层，围绕异质界面可键合性技术问题和微观键合机制科学问题，从键合能理论测算、外延薄膜制备、键合工艺集成、反应机制研究等环节建立成套研究方案，并取得了如下重要结果和关键数据：.（1）提出了羟基吸附简易判定规则，发展了基于分子表面构型的键合能快速算法，确定了适用于辅助键合的氧化镓薄膜最优β相同分异构体和-201结晶晶向；基于微观表面高斯分布的可键合因子理论，全面理清了氧化镓辅助键合的关键参数要求，并根据氧化镓材料特点和现有工艺水平确定了最优改进方向；.（2）重点针对外延生长的两性“氧化镓”粗糙度高的难点问题，从薄膜外延生长、CMP加工和表面活化等三个环节进行调控方法研究，并揭示晶粒尺寸、生长速率、研磨垫刚度、活化配方等核心因子的调控规律，初步建立关于两性氧化物“氧化镓”粗糙度调控的工艺体系，实现厚膜抛光片活化粗糙度1nm水平，薄膜活化粗糙度0.46nm水平；.（3）建立Ga2O3辅助GaN-to-Si异质键合的键合架构和成套工艺流程，并部署了核心专利[GaN与Si材料异质键合结构，201711066953.8] ，初步揭示氧化镓亲水性键合的化学反应机制，实现了200℃以下2英寸晶圆区域键合，辅助层厚度小于800nm，为实现兼容CMOS工艺的GaN-to-Si异质材料的可靠键合探索新的思路和途径，这对绕开国外技术壁垒，推动单片功能集成具有重要战略意义。.本项目的实施和关联研究成果成为所企共建宽禁带电力电子工程技术研究中心的重要基础之一，围绕本项目部署的硅基氮化镓产业化项目也获得中科院科技服务网络计划（STS）区域中心项目的重点支持；依托本项目及关联项目成果，项目负责人晋升副研究员并入选2017年度中国科学院青年创新促进会会员，同时培养该方向硕士生2名，研究成果申请中国专利2项。