Sites:
Home > Technical Library > Semiconductors > W: wafer - write-through

W: wafer - write-through

By Michael Barr
From Embedded Systems Dictionary

wafer

n. The nearly round disk of silicon onto which semiconductor vendors create many ICs. Chips are made by depositing chemicals on silicon wafers using photomasks in a process reminiscent of silkscreening but on an almost atomic scale. Each wafer contains hundreds or thousands of individual chips (usually all of the same design). A dicing operation cuts the wafer into the individual chips, which are then packaged.

Today s manufacturing processes use 200-mm-diameter wafers on the older technology fab lines and 300 mm on newer ones. It s pretty astonishing to consider that across that huge 300-mm (12-inch) disk, line widths are controlled to better than 90 nm (1000 atoms).

wait

n. A microprocessor input that indicates the memory or I/O addressed in the current cycle needs more time to finish returning the requested data. Wait is generally active low on most processors. See also ready.

wait state

n. An idle cycle used to give memory or I/O more time to respond. Wait states can be requested by memory systems or I/O devices or (as is more common in embedded systems) created by the processor s own wait state circuits. When the processor services a wait state request, it idles, issuing no bus activity for the entire cycle.

walking 0s test

n. A memory test that involves moving a 0 bit through a byte or word to systematically confirm that each bit can hold a 0 value. All of the other bits are set to 1 during the test. A walking 0s...

Copyright CMP Books 2003 under license agreement with Books24x7
Products & Services
SRAM Memory Chips
Static random access memory (SRAM) chips do not need to be refreshed like DRAM chips. This makes SRAM chips faster and more reliable.
FLASH Memory Chips
FLASH memory chips offer extremely fast access times, low power consumption, and relative immunity to severe shock or vibration. They do not need a constant power supply to retain their data. 
CPU Chips
CPU chips or central processing unit chips are used in digital computers and are the semiconductor component where most calculations take place.
DRAM and SDRAM Memory Chips
Dynamic random access memory (DRAM) chips are single-transistor memory cells that use small capacitors to store each bit of memory in an addressable format that consists of rows and columns. Because capacitors are unable to hold a charge indefinitely, DRAM memory chips require a near-constant pulse of current to retain stored information.
Semiconductor Equipment Repair Services
Semiconductor equipment repair services repair, rebuild and refurbish equipment related to the manufacture and processing of semiconductors.
Topics of Interest

X-Acto knife (ex act toe) N. A small, razor-sharp knife with a disposable blade used (in electronics) to remove solder bridges between IC pins, clean up PCB tracks, and trim fingernails. The X-Acto...

Overview In this chapter, the preparation of semiconductor-grade silicon from sand, its conversion into crystals and wafers (material preparation stage), and the processes required to produce...

Wider 'Net-based tool diagnosis is becoming a remote possibility Applied enters yet another market segment with introduction of Swift implantation tool New head of silicon house foresees 5�19%...

Lawrence B. Levit and Arnold Steinman, The institution of an effective static control program in photolithography areas can greatly reduce static-charge events, leading to a reduction in wafer scrap...

L1 cache n. A zero wait state cache located onboard the microprocessor. See also cache memory, L2 cache. L2 cache n. A cache that requires a few wait states, located between the L1 cache and...