You are here

Embedded Flash Memory Technology | Cypress Semiconductor

Embedded Flash Memory Technology

Embedded Flash (eFlash) memory is a key enabling technology for many programmable semiconductor products requiring small form factor and low-power processing. For example, microcontrollers use eFlash to store program instructions (code) as well as data on which processing is performed. The ability to update the code and data is essential.

IoT devices use eFlash to enable smart, flexible, and secure products that can be updated wirelessly, or over-the-air (OTA). Electronic devices with eFlash enable a wide-range of products from smart cards and wearables to factory automation systems and autonomous vehicles.

Cypress developed two different eFlash memory solutions, SONOS (Silicon Oxide Nitride Oxide Silicon) and eCT™ (embedded Charge Trap), to cover the application requirements from low-cost consumer to high-performance automotive. Both technologies are very compatible with CMOS and have been integrated into a foundry-standard logic processes while preserving CMOS device models and existing design IP.

Cypress uses these eFlash solutions in our microcontroller products (MCUs) for consumer, industrial and automotive markets. We've shipped billions of MCUs containing our eFlash technology over nearly two decades, demonstrating that our eFlash solutions are robust and proven. And, Cypress makes our eFlash solutions available for licensing to third-party companies.

Learn about Infineon Automotive Transceivers

Cypress’ SONOS is a patented and proprietary NOR Flash technology that was developed for cost-effective MCUs with low-power requirements. SONOS is a transistor with a polysilicon gate (S), an Oxide Nitride Oxide (ONO) gate dielectric, and a Silicon substrate (S) whose threshold voltage (Vt) can be changed by adding or removing electric charge from the nitride (ONO) layer. Cypress’ SONOS eFlash has been in production since 2001 on 350 nm and 130 nm nodes, and is now available on 65 nm, 55 nm, 40 nm and 28 nm nodes.

Cypress’ SONOS eFlash bit cell contains two transistors: a SONOS (Control Gate) and a MOS (Select Gate). One cell stores one bit of data for Flash or EEPROM.

The SONOS transistor is programmed by FN tunneling of electrons from the channel’s inversion layer through the bottom oxide of ONO and into traps within the nitride layer of ONO. It is erased by FN tunneling of holes from the channel’s accumulation layer into traps within the nitride layer of ONO.

Program (left) and erase (right) operations by FN tunneling

The Cypress 55 nm and 40 nm SONOS eFlash macro families offer the most cost-effective, robust embedded Flash solutions for the next-generation 32-bit MCUs and IoT devices.

  • Low extra mask count (four to five) reduces manufacturing cost dramatically
  • Low-current program/erase methods and three power-saving modes reduce power consumption
  • Read operation at minimum power supply of 0.81 V
  • Densities from 1 Mb up to 16 Mb
  • Data output bus width from 32 bits up to 256 bits
  • Random access time of 25 ns
  • Temperature ranges: Industrial (-40°C to +85°C), Industrial-plus (-40°C to +105°C),
    Automotive Grade 3 (-40°C to +85°C), Automotive Grade 2 (-40°C to +105°C)
  • 100,000 write endurance cycles
  • 10 years of data retention


SONOS eFlash 55 nm 40 nm
Cell Architecture 2T, 1 bit/cell 2T, 1 bit/cell
Density 1 Mb, 2 Mb, 4 Mb, 8 Mb, 16 Mb 1 Mb, 2 Mb, 4 Mb, 8 Mb, 16 Mb
Word Size 32-bit 32-bit
Output Bus Width 32, 64, 128-bit 32, 64, 128, 256-bit
Supply Voltage 0.90 V – 1.32 V
1.62 V – 3.63 V
0.81 V – 1.21 V
1.62 V – 3.63 V
Operating Temperature (Junction) -40°C to +110°C -40°C to +110°C
Read Access Time 25 ns 25 ns
Page Size 4 kb 4 kb / 8 kb
Page Programming Time (typ.) 2 ms 2 ms
Erase Sector Size 1 Mb 1 Mb / 2 Mb
Sector Erase Time (typ.) 6 ms 6 ms
Write Endurance 100 k 100 k
Data Retention 10 years 10 years
Extra Masks 4 5

eCT is a patented and proprietary NOR Flash technology that Cypress developed for high-performance MCUs with stringent reliability requirements. eCT Flash is based on charge-trap technology that has been proven in volume production in six technology generations of MirrorBit® NOR Flash memory. eCT has been in volume production at the 40 nm node since 2016.

eCT Flash bit cell uses a split-gate (1.5T) architecture in which one transistor is a Memory Gate (MG) that stores non-volatile data, and the other is a Select Gate (SG). The threshold voltage (Vt) of MG can be changed by adding or removing the electric charge from the nitride layer of an Oxide Nitride Oxide (ONO) gate dielectric.

MG is programmed by channel hot electron injection (CHEI); Vt is increased by injecting electrons into traps within the nitride layer of ONO. The erase operation is accomplished by band-to-band tunneling (BTBT) hot hole injection. Vt is decreased by injecting holes into traps within the ONO nitride layer.

Program (left) operation by CHEI and erase operation (right) by BTBT hot hole injection

The Cypress 40 nm eCT Flash technology offers the most scalable high-performance, high-reliability embedded Flash solution for storing critical code and data with automotive reliability.

  • Random access time of 8 ns
  • Fast word-programming speed
  • Industry-leading bit cell size on 40 nm node and validated bit cell at 22 nm
  • Densities from 512 kb up to 64 Mb
  • Word size: 32 or 64 bits
  • AEC-Q100 qualification passed for Automotive Grade 1
  • Temperature ranges: Automotive Grade 1 (-40°C to +125°C)
  • Superior write endurance and data retention


Technology 40 nm eCT Flash
Code Flash Data Flash
Density 4 Mb, 8 Mb, 16 Mb, 32 Mb, 48 Mb, 64 Mb 512 kb, 1 Mb, 2 Mb, 4 Mb
Word Size 64-bit 32-bit
Output Bus Width 256-bit 32-bit
Supply Voltage 0.99 V – 1.21 V
2.70 V – 5.50 V
0.99 V – 1.21 V
2.70 V – 5.50 V
Operating Temperature (Junction) -40°C to +150°C -40°C to +150°C
Read Access Time 8 ns 50 ns
Word Programming Time (typ.) 30 µs 30 µs
Page Size 4 kb -
Page Programming Time (typ.) 320 µs -
Erase Sector Size 64 kb 1 kb
Sector Erase Time (typ.) 15 ms 5 ms
Write Endurance 1 k 125 k
Data Retention 20 years 20 years
Document Type Title English
Brochures SONOS eFlash Technology Brochure
eCT Flash Technology Brochure
Press Releases

HLMC and Cypress Announce Initial Production Milestone of Embedded Flash Using 55-Nanometer Low Power Process Technology with SONOS Flash
Cypress Licenses 40-Nanometer Embedded Flash IP to UMC, Enabling Next-Generation MCUs, IoT and Wearables Applications
Cypress and HLMC Demonstrate Working Silicon Cells Leveraging 55-Nanometer Embedded Flash IP
Cypress Licenses 55-Nanometer Embedded Flash IP to UMC
Cypress and UMC Announce Joint Technology Development and Licensing Agreement
Cypress and UMC Deliver ICs On New 65-Nanometer SONOS Embedded Flash Technology


Contact Us

Application Notes

Contact Us

White Paper

Cypress SONOS Technology


K. Ramkumar, I. Kouznetsov, V. Prabhakar, K. Shakeri, X. Yu, Y. Yang, L. Hinh, S. Lee, S. Samantha, H.M. Shih, S. Geha, P.C. Shih, C.C. Huang, H.C. Lee, S.H. Wu, J.H. Gau, Y.K. Sheu, “A scalable, low voltage, low cost SONOS memory technology for embedded NVM applications,” in Proc. IEEE IMW, May 2013, pp. 199-202.
H. Puchner, P. Ruths, V. Prabhakar, I. Kouznetsov, S. Geha, “Impact of total ionizing dose on the data retention of a 65 nm SONOS-based NOR Flash,” IEEE Trans. Nucl. Sci., vol. 61, no. 6, pp. 3005-3009, Dec. 2014.


Process License

The Cypress SONOS and eCT Flash process technologies are available for licensing to foundries. Under this license, Cypress transfers specific technology information to enable the integration of the embedded Flash technology into a specific logic or mixed-signal process for wafer manufacturing at the foundry. Cypress’ SONOS and eCT Flash technologies do not change any existing process design rules, device models or design IP. Cypress also works with foundries to provide all documentation necessary for a complete process design kit.

Design Creation License

Cypress’ SONOS and eCT Flash design technologies are available for licensing to fabless semiconductor companies, IDMs, or foundries with design IP development teams. Under this license, Cypress transfers design information necessary for creation of new embedded Flash macro designs in Cypress’ SONOS or eCT Flash technologies by a customer’s design team.

Design Use License and Design Services

Customers can also license our available off-the-shelf, silicon-validated SONOS or eCT macro designs. This option establishes the fastest path to market. Additionally, Cypress has a team of experienced engineers dedicated to providing custom Flash macro design services. In these cases, dedicated engineers consult with customer teams, engineer custom solutions and provide "design kit" Flash macros for integration into customer's products.

Get Started Now

Please contact us at: