MOCVD气体混合系统的泄漏检测研究

发布时间：2018-01-10 10:11

本文关键词：MOCVD气体混合系统的泄漏检测研究　出处：《西安电子科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：近年来,发光二极管(LED)由于其体积小、寿命长、耗能低等诸多优点受到了学者和市场的广泛关注。和传统的白炽灯、卤素灯相比,基于蓝光LED芯片的照明设备拥有更高的电光转换效率和更好的可靠性,在固态照明和背光源领域得到了广泛的应用。金属有机物化学气相沉积法(MOCVD)是进行外延生长蓝光LED的核心工艺,然而在使用中会碰到气体泄漏的问题,特别是对于内漏的测试缺乏系统的方法。本文对MOCVD的气体混合系统和控制系统进行了研究,提出了检测泄漏的方法和流程,并基于设备的控制软件开发了自动检测程序,主要的研究内容为：1.论述了MOCVD的组成和原理,说明了气体混合系统结构并研究了泄漏的原因和影响。MOCVD通常由气体混合系统、反应室、加热系统、废气排放系统、控制系统和辅助系统组成。载气通过质量流量控制器(MFC)和压力控制器(PC)的调整携带有机金属源,氨气和硅烷被MFC调整之后流入反应室和有机金属源发生反应。控制系统是整台设备的中枢,从系统中所有执行器和传感器获取实时数据并向执行器发号指令。气体混合系统分为五条支路,载气起到运输和稀释的作用,四种不同结构的阀件负责改变气体流向和切换气体种类。系统泄漏分为外部泄漏和内部泄漏,外漏是因为接口或者器件的密封不良导致,会引入大气：内漏表现为阀件的阀头磨损无法完全密闭,造成关闭时仍然有气体流通。2.分析了原有控制系统的构成和工作原理。控制系统的硬件核心是PLC控制器,它通过Ethernet/IP和DeviceNet通讯协议将所有执行器和传感器组成了控制网络,实现了实时控制和数据传输。Aixact软件是控制系统和用户之间的桥梁,用户通过人机界面了解系统状态,通过历史记录查询参数档案,还可以通过编写程序使设备自动执行生产任务。3.对泄漏问题的分析和处理方法进行了系统的研究。外漏可以通过保压法和氦气测漏法进行检测,然后更换失效的密封件解决。由于内漏发生在阀件内部,无法通过外界工具进行判断,只能根据不同阀件的特点逐一排查。在测试过程中,为了达到不同阀头同时关闭的状态,需要用到短接的方法。确定发生内漏的阀件和类型需要灵活的设计测试流程,搭配阀件、MFC和PC的设置来进行。4.利用Aixact软件开发了自动检测泄漏的程序。Aixact软件中的Recipe manage功能提供给用户一个程序开发平台,用户可以根据需求自行编写程序。在归纳出检测泄漏问题的方法之后,按照这套流程编写设备可执行的程序大大提高了检测效率,降低了操作失误的可能性,符合生产的实际需求。实践证明这种方法可以迅速有效的排查内漏,帮助我们解决因泄漏带来的产品异常。
[Abstract]:In recent years, LED) has attracted wide attention of scholars and markets because of its small size, long life, low energy consumption and so on, compared with traditional incandescent lamps and halogen lamps. The lighting equipment based on Blu-ray LED chip has higher electro-optic conversion efficiency and better reliability. MOCVD is widely used in the field of solid state lighting and backlight. Metal organic chemical vapor deposition is the core process for epitaxial growth of blue LED. However, the problem of gas leakage will be encountered in use, especially the lack of systematic methods for testing internal leakage. In this paper, the gas mixing system and control system of MOCVD are studied. The method and flow of leak detection are put forward, and the automatic detection program is developed based on the control software of the equipment. The main research content is: 1. The composition and principle of MOCVD are discussed. This paper describes the structure of gas mixing system and studies the causes and effects of leakage. MOCVD usually consists of gas mixing system, reaction chamber, heating system and exhaust gas emission system. Control system and auxiliary system composition. Carrier gas through the mass flow controller MFC and pressure controller to carry the adjustment of organic metal sources. After ammonia and silane are adjusted by MFC, they flow into the reactor and react with organometallic sources. The control system is the center of the whole equipment. Real time data are obtained from all actuators and sensors in the system and instructions are issued to the actuators. The gas mixture system is divided into five branches, and the carrier gas plays the role of transportation and dilution. Four different structure valves are responsible for changing gas flow and switching gas types. System leakage is divided into external leakage and internal leakage due to poor sealing of the interface or device. Will introduce the atmosphere: internal leakage shows that the valve head wear can not be completely closed. The composition and working principle of the original control system are analyzed. The hardware core of the control system is the PLC controller. It uses Ethernet/IP and DeviceNet communication protocol to form a control network of all actuators and sensors. The real-time control and data transmission. Aixact software is the bridge between the control system and the user. The user knows the system status through the man-machine interface, and queries the parameter files through the history record. It is also possible to write a program to make the equipment carry out production tasks automatically. 3. The leak analysis and treatment methods are systematically studied. The leakage can be detected by the pressure retaining method and the helium leak detection method. Because the internal leakage occurred inside the valve, it can not be judged by outside tools, so it can only be checked one by one according to the characteristics of different valves. In order to achieve the state of different valve heads closing at the same time, it is necessary to use the method of short connection. It is necessary to design test flow flexibly and match the valve parts to determine the valve parts and types that occur internal leakage. MFC and PC settings. 4. Using Aixact software to develop an automatic leak detection program. Aixact software in the Recipe. The manage function provides the user with a program development platform. Users can write their own programs according to their needs. After summing up the methods of detecting leakage problems, the program that can be executed by the equipment according to this process greatly improves the detection efficiency and reduces the possibility of operation errors. It is proved that this method can quickly and effectively detect internal leakage and help us solve the product anomalies caused by leakage.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN312.8

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