Tấm silicon - vật liệu ban đầu dùng trong ngành công nghệ vi điện tử là các phiến silicon (silicon wafer) có bề dày cỡ 400 micro-mét với đường kính khác nhau (tấm silicon có đường kính lớn nhất mà người ta có thể chế tạo là 12 inch, nghĩa là tương đương một chiếc piza lớn). Tấm silicon có đường kính càng lớn thì càng khó chế tạo, thiết bị dành cho công nghệ tấm lớn càng tốn kém nhưng số linh kiện thu được trên một tấm lại được nâng cao. . | CHAPTER TECHNOLOGY INTRODUCTION A good understanding of processing and fabrication technology on the part of the circuit designer is necessary to provide the flexibility needed to optimize integrated circuit designs. With this knowledge the actual layout can be considered during design and the appropriate parasitics can be included in the analysis. Innovative techniques that improve performance often involve circuits or geometries that are dependent on and applicable to a particular process. Knowledge of processing characteristics enables the designer to make yield calculations during design and consider tradeoffs between yield performance and design simplicity. In this chapter processing technology is discussed from a qualitative viewpoint. This is followed by a detailed discussion of typical NMOS CMOS bipolar thick film and thin film processes. Most processes in industry can be viewed as either a straightforward variant or extension of these processes. These processes are summarized in the appendices of this chapter. Included in the appendices are process scenarios graphical process descriptions design rules process parameters and some computer simulation model parameters. These appendices should provide a useful reference for material that is presented in later chapters of this book. This chapter is concluded with a discussion of practical layout considerations and comments about some CAD tools that have become an integral part of the IC design process. 41 IC PRODUCTION PROCESS The major steps involved in producing integrated circuits are considered from a qualitative viewpoint in this section. These steps arc used in the MOS and or bipolar processes that will be discussed later in this chapter. Processing Steps CRYSTAL PREPARATION The substrate of bipolar and MOS integrated circuits is generally a single crystal of silicon that is lightly doped with either n- or p-typc impurities. The substrate serves both as the physical medium upon and within .
