Mask ROM (MROM) chips contain a software mask that is burned onto the chip during the design phase of the semiconductor manufacturing process.

In high volumes, mask read-only memory (ROM) is a cost-effective alternative to the following:

• Programmable read-only memory (PROM)
• Erasable read-only memory (EEROM)
• Electrically erasable read-only memory (EEPROM)
• Non-volatile read only memory (NVRAM)
• Flash memory

Unlike these other computer memory chips, Mask ROM (MROM) chips are produced by arranging transistors before the semiconductor manufacturing process actually begins. Often, Mask ROM (MROM) chips are used in computer systems that require long-term sustainability.

Examples of computer systems that use Mask ROM chips or MROM chips include network operating systems and server operating systems. Other computer systems typically use a different computer memory type.

Specifications

To produce Mask ROM (MROM) chips, integrated circuits (ICs) are masked during the design phase of the semiconductor fabrication process. In its simplest form, a semiconductor is defined as a material that is half-conductive and half-insular, and that can be altered by electrical impulses.

Design considerations for a mask ROM chip or MROM chip include transistor width and placement. Often, this is the sole consideration of a mask ROM chip designer, since process engineers typically lay out all of the other parameters before tanking.

There are two types of semiconductors:

• N-type
• P-type

N-type semiconductors contain higher concentrations of electrons.

P-type semiconductors contain lower concentrations.

This distinction is responsible for overall design differences in the production of Mask ROM (MROM) chips, since lower concentrations do not permit the hardwiring of as many transistors. In turn, these differences affect the capacitance and storage density abilities of the IC.

Suppliers of Mask ROM (MROM) chips are located across the United States and around the world. They conform to a variety of quality standards.

MASK ROM chip manufacturers are less numerous than producers of PROM chips, EPROM chips, EEPROM chips, NVRAM chips, and Flash memory chips.

The reason for this disparity is that Mask ROM (MROM) chips are cost-effective to produce only if high production volumes are required.

Standards

SMD 5962-98586 - Microcircuit, memory, digital, bicmos, 512 x 8-bit custom masked rom, monolithic silicon. 

SMD 5962-98644 - Microcircuit, memory, digital, cmos, soi, radiation- hardened, 32k x 8-bit mask programmable rom, monolithic silicon.

SMD 5962-97517 - Microcircuit, memory, digital, cmos, radiation- hardened, 32k x 8-bit mask programmable rom, monolithic silicon.

SMD 5962-97544 - Microcircuit, memory, digital, cmos, radiation-hardened, 8k x 8-bit mask programmable rom, monolithic silicon.

References

Image Credits:

AMIC Technology | LAPIS Semiconductor