What is Very Large Scale Integration (VLSI)?

VLSI is an abbreviation for Very Large Scale Integration, which refers to an integrated circuit that integrates tens of thousands to millions of transistors on a silicon wafer of a few millimeters square and has a line width of less than 1 micron. Because the transistors and wiring are completed at once, the man-hours and costs of making several to millions of transistors are equivalent. In mass production, hardware costs are almost negligible and depend on design costs.

VLSI was successfully developed in the late 1970s and is mainly used to manufacture memories and microprocessors. 64k-bit random access memory is the first generation of ultra-large-scale integrated circuits, which contains about 150,000 components and a line width of 3 microns. At present, the integration level of VLSI has reached 6 million transistors, and the line width has reached 0.3 microns. Electronic equipment manufactured by VLSI has small size, light weight, low power consumption, and high reliability. The use of VLSI technology can "integrate" an electronic sub-system and even the entire electronic system on a single chip, completing various functions such as information collection, processing, and storage. For example, the entire 386 microprocessor circuit can be integrated on one chip with an integration level of 2.5 million transistors. The successful development of VLSI is a leap in microelectronics technology, which has greatly promoted the advancement of electronic technology, thereby driving the development of military and civilian technology. VLSI has become an important indicator of the level of a country's science and technology and industrial development. It is also one of the most competitive areas in the world's major industrial countries, especially the United States and Japan. VLSI will continue to develop.

Integrated circuits can be divided into different levels of integration

In engineering applications, reliability technology runs through all stages and aspects of VLSI demand analysis, product design, manufacturing process, test and detection, and application. The development of military electronics and aerospace technology has placed increasing requirements on VLSI. , Has promoted the continuous development of VLSI reliability technology. Due to the development of technology and demand, VLSI reliability assurance has gradually controlled the reliability of the final product mainly through reliability testing and screening, and has gradually shifted to strengthening process control and strengthening the coordination of reliability design and function design. At the same time of process capability and functional design, countermeasures are proposed for the main failure mechanism, and the reliability index and cost of VLSI in the whole life cycle and under specific environmental conditions are comprehensively weighed. Based on this, circuit design, structural design, and layout Layout, material selection, process flow and parameter selection, process control, design verification and process evaluation, product reliability test evaluation and screening, etc. introduce appropriate reliability technologies to ensure the reliability of the product and improve it. VLSI reliability technology includes five major technical directions: reliability design and simulation, reliability test and evaluation, process quality control, failure mechanism and model research, and failure analysis technology. With the continuous deepening of reliability physics research, VLSI reliability technology shows a trend of modeling, quantification and integration.
Because VLSI integration has always followed the "Moore's Law" and has doubled every 18 months, the number of integrated circuit components on a chip has already exceeded 100 million. This development trend is making VLSI play a role in electronic equipment. The role has changed from a device chip to a system-on-chip (SOC); at the same time, the deep submicron VLSI process feature size has reached less than 0.18 m. With the shrinking feature size, integration, chip area, and actual power consumption, The approximation of the physical limit increases the sensitivity of various failure mechanism effects that affect VLSI reliability. The factors that need to be considered and weighed in design and process are greatly increased, and the remaining reliability tolerance tends to disappear. Improving faces huge challenges. Therefore, the international reliability research on the main failure mechanism of deep submicron / ultra deep submicron VLSI has been continuously deepened. New failure analysis technologies and equipment have continuously appeared. The world's famous integrated circuit manufacturers have established their own VLSI. Quality and reliability assurance system, and the development and application of wafer-level and package-level reliability evaluation test structures for VLSI's main failure mechanisms are included in its quality assurance plan, and the application of reliability simulation in reliability design and evaluation is increasing . While further improving reliability technologies such as wafer-level reliability (WLR), statistical process control (SPC), and reliability-oriented experimental design methods (DOE), internationally proposed built-in reliability (BIR) in the 1990s The new concept applies the various reliability technologies in a targeted and quantitative manner to the R & D and production process of VLSI, and builds a VLSI quality and reliability guarantee system from a technical and management perspective to meet users' requirements for reducing VLSI failure rates. Increasingly higher requirements to improve its reliability.

In China, after nearly two five-year studies and practices, VLSI reliability technology has reached a new level of development and application. In terms of VLSI process reliability evaluation and assurance technology, a wafer-level reliability technology WLR for production lines for domestic key integrated circuit research has been established, including process quality evaluation PCM technology, reliability evaluation REM technology, and process quality control SPC technology. The process quality control and reliability guarantee in the circuit manufacturing stage provide the necessary methods and means to provide a quantitative basis for assessing the quality and reliability level of the process line. In terms of VLSI reliability design, simulation and analysis technology, for the current VLSI design stage Research on reliability design technology for the main failure mechanism was carried out, and the integrated circuit reliability comprehensive simulator ISRIC was developed on its own. The electron beam test, light emission fault diagnosis, electronic microprobe analysis and IDDQ test is the core comprehensive failure locating technology, and the effectiveness of these technologies is implemented and verified, which meets the requirements of practical engineering. These technologies are consistent with the reliability evaluation methods and technologies commonly used abroad in the 1990s, especially in recent years. They have the characteristics of advanced technology and strong practicality, and are applied in several typical integrated circuit production lines and multiple circuit products in China. It plays an important role in stabilizing the process and improving the process yield, achieving batch process reliability evaluation and process reliability consistency monitoring, and ensuring the reliability of integrated circuit process platforms and circuit products. The development of VLSI reliability technology in China has the following characteristics:
(1) Through failure mode and failure mechanism analysis, reveal the underlying root causes that cause failure and affect reliability, and conduct targeted reliability designfailure analysisinformation feedbackdesign improvement, form a cycle, and promote in this way. VLSI inherent reliability level is improved.
(2) Keep up with the development trend of international advanced VLSI reliability technology, such as WLR technology, reliability simulation technology, advanced failure analysis technology, etc., and conduct in-depth research and engineering applications.
(3) Due to the gap between the technology platform of VLSI reliability technology application in China and foreign countries, the focus of our current research and resolution is on the reliability of micro / sub-micro devices, and the object of international reliability research is ultra-deep Asia Micron device reliability issues. ?
(4) China's VLSI reliability technology is oriented to engineering applications and has strong practicability. Process reliability evaluation and assurance technologies with PCM, REM and SPC as the core have been adopted and achieved results.
The next ten years will be a decade of great development of the domestic VLSI industry and technology. A number of microelectronics industrial bases will be built to form a design, manufacturing, testing, and packaging enterprise group with VLSI processing technologies below 0.25 m as the core, and will drive the nationwide The boom of microelectronics technology. The development of VLSI reliability technology must seize the opportunity, rely on this development trend, highlight the key points, and promote development with applications.
(1) During the Tenth Five-Year Plan period, further strengthen investment in VLSI reliability application research, and develop VLSI reliability design and verification technologies, such as ASIC, especially SOC, CPU, and DSP, and wafer-level (WLR) Reliability evaluation and assurance technology, Foundry standard process line reliability parameter library technology, ultra-deep submicron device failure physics research, new materials, new device structure failure mechanism research, nondestructive testing and evaluation screening new method research, and new Research on failure analysis technology, effectively control various failure modes, and achieve reliability growth.
(2) Relying on the technical and equipment conditions of microelectronic device reliability research by the State Key Laboratory of Reliability Physics and Application Technology of Electronic Components, through further capacity expansion, VLSI reliability evaluation, testing, screening, and aging are formed , Failure analysis and other series of reliable technical support systems, to provide relevant technical services for the semiconductor industry.
(3) Formulate and implement reliability-related standards. Complement and improve existing reliability standards in national standards, national military standards, and enterprise standards, and establish and improve various industry standards, specifications, and implementation rules for reliability design, evaluation, testing, process control, and simulation to enable VLSI design There are quantitative assessment standards and basis for the reliability of the process and the process, to ensure the process yield and product reliability. ?
(4) The comprehensive promotion and application of mature reliability technologies is the key to the implementation of the VLSI reliability assurance plan. In particular, process capability assessment of standard process lines, SPC control technology, reliability evaluation technology of standard technology, reliability design and simulation evaluation technology, etc. should be promoted and applied throughout the industry.