Dynamic-random-access-memory chip

FIGURE 4.1 Chemical reactions are used to achieve the fine structures seen in modern integrated circuits. This electron micrograph shows a transistor in a "cell" of a 1-mega-bit dynamic random access memory chip. The distance between features is about 1 pm. Courtesy, AT T Bell Laboratories. 

Michaelis reviews the application of valve metals in electronics based on the dielectric properties of ultra-thin films. Following presentation of fundamental principles and experimental details, the discussion of valve metal systems includes thin film oxide behavior of Ti, Zr, Hf, Nb, Ta, and Al. The application of these valve metal systems in electrolytic capacitor manufacturing is discussed with emphasis on current development trends and research issues. In addition, special emphasis on Si02 dielectric films is provided for integrated circuit applications associated with dynamic random access memory chip fabrication. 

The alloy W-lOTi is used as a sputtering target in the manufacture of microelectronics devices, such as VLSI, ULSI (very large resp. ultralarge-scale integration), and DRAM (dynamic random access memory) chips. Thin W-Ti layers are sputtered onto silicon substrates and act as a diffusion barrier against aluminum (intercormect). 

Capacitors are charge storage devices that are essential in many circuit families, including dynamic random access memory, DRAM, and RF chips. For example, in RF chips, capacitors occupy a large fraction (at present about 50 %) of the area of the... 

As an example of Si technology, Figure 1 illustrates a packaged 1-megabit dynamic-random-access-memory (DRAM) chip on a 150-mm-diameter Si substrate containing fabricated chips. Each of the chips will be cut from the wafer, tested, and packaged like the chip shown on top of the wafer. The chip is based on a l- xm minimum feature size and contains 2,178,784 active devices. It can store 1,048,516 bits of information, which corresponds to approximately 100 typewritten pages. 

Figure 1. A packaged 1-megabit dynamic-random-access-memory (DRAM) silicon chip on a processed 150-mm-diameter Si wafer. (Used by courtesy of G. B. Larrabee, Texas Instruments.)...

Over the past three decades, enormous progress has been made in materials and materials processing used to fabricate electronic devices. This progress has made possible an astonishing increase in device complexity and decrease in the dimensions of features used to fabricate the circuit, which, in turn, has led to improved performance and reduced cost per function. Figure 1 illustrates these trends for dynamic random access memory (DRAM), historically the most complex chip produced in terms of feature size and components per chip. 

This increase in circuit density is made possible only by decreasing the minimum feature size on the chip. Figure 2 illustrates the decrease in minimum feature size as a function of time for dynamic random access memory (DRAM) devices. In 1975, the 4-kilobit DRAM (4 X 10 memory cells or about 8.2 X 10 transistors) had features in the 7-9-(xm range, and by 1987,... 

DRAM DRAM is dynamic random access memory. This is actually the RAM that most people are talking about when they mention RAM. When you expand the memory in a computer, you are adding DRAM chips. The reason you use DRAM to expand the memory in the computer is because it s cheaper than any other type of memory. Dynamic RAM chips are cheaper to manufacture than other types because they are less complex. Dynamic refers to the chips need for a constant update signal (also called a refresh signal) in order to keep the information that is written there. 

One underlying reason for the Japanese success was its impressive commercializing of a new memory chip, the DRAM (Dynamic Random Access Memory), initially introduced by Intel in 1971. As its New Series Project was being fulfilled, MITI formed a new project, the Very Large-Scale Integrated (VLSI) circuit, which would coordinate the activities of the four major computer companies in commercializing the DRAM memory chip. 

An important potential application for ferroelectrics is their incorporation as thin films into dynamic random access memories (DRAMs). The majority of the memory in a computer is DRAM. Information is stored in millions of tiny capacitors, each representing a single bit. The capacitors used in DRAM chips are fabricated directly onto the silicon substrate. 

Abbreviations OE, optoelectronic DRAM, dynamic random access memory I/O, input/output ATM, asynchronous transfer mode VLSI, v y large scale integration ASIC, application-specific integrated circuit. [From Pinkston, T. M., and Kuznia, C. (1997). Smart-Pixel-Based Netwa-k Interface Chip, App/. Optics 36(20), 4871-4880.]... 

The average mid-range personal computer generally contains between 50 ICs and 75 ICs (chips). A chip combines the functions of discrete electronic devices, such as vacuum tubes, resistors and capacitors, and performs complicated electronic functions in a fraction of a second [7]. The most complex chip is the microprocessor, which executes a stream of instructions that operate on data. The microprocessor has direct access to an array of dynamic random access memory (DRAM) chips, where instructions and data are temporarily stored for execution. A state of the art PC might have 8 DRAM chips, each capable of storing 8,388,608 bytes (64 megabits) of data. In addition to the microprocessor and DRAMs, there are many other kinds of chips that perform such tasks as amplification, synchronisation and communication. 

Zilog in July 1976 introduced the Z-80, which was intended to be an improved 8080. It also used 8-b data and 16-b address, could execute all of the opcodes of the 8080 and added 80 more instructions. The register set was doubled and consisted of two banks, which could be switched. Two index registers (IX and lY) allowed for more complex memory instructions. Probably the most successful feature of the Z-80 was its memory interface. Until its introduction, dynamic random-access memory (RAM) had to be refreshed with rather complex external circuitry, which made small computing systems more complex and expensive. The Z-80 was the first chip to incorporate this refreshing capability on-chip, which increased its popularity among system developers. The Z-8 was an embedded processor similar to the Z-80 with on-chip RAM and read-only memory (ROM). It was available in clock speeds to 20 MHz and was used in a variety of small microprocessor-based control systems. 

Memory Designs can contain read-only memory (ROM), dynamic random-access memory (DRAM), and static random-access memory (SRAM). In addition, MICON also supports the use of cache memtMies wh cache controller chips exist in the family, such as the Intel 80386/82385 combination. 

The bottom leadless package (BLP) is a peripheral package for replacing the thin small outline package (TSOP) for dynamic random access memory (DRAM) applications. This package uses a custom-designed lead-frame with wire bond interconnection at the chip level. A package with 46 I/O, 0.5 mm (0.02 in.) pitch, was subjected to numerous thermal cycles to determine the cycles-to-failure and the failure mechanisms (Ref 10). 

Fig. 32.1 A plot depicting the number of transistors per die in the various dynamic random access memory (DRAM) chips ranging from the 1 Kbit to 64 Mbit chips as a function of the year the chips were first available. (From Ref. 3.)...

The minimum line width on chips produced by photolithography has decreased steadily from year to year. As a rule of thumb, the minimum feature size on a dynamic random access memory (DRAM) silicon chip has decreased by a factor of... 

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