In the automotive Integrated Circuit industry, high reliability and low defects are two essential elements to avoid breakdowns and accidents. High reliability means that a good component can still be in a good functional state after being used for long period of time. Low defects mean any malfunctioning part can be screened out before being used in a car or ECU.
To achieve the automotive semiconductor requirements of zero defects, the OTP memory needs to be capable of 100% testability to ensure that defective parts can be discovered and removed. The fact is that conventional OTP techniques always| typically had problem with 100% testability. Ideally, every OTP bit should be programmed at the very least once to ensure it can be programmed. Because of the nature of one-time programmability, if a bit has been programmed during test, the OTP macro cannot be used any more.
Further, in a newly produced blanc OTP block all OTP bits should be read as 0. But one must determine if those unprogrammed bit cells are programmable. If bits cannot be fully tested for programmability, it is impossible to avoid yield loss when the OTP is being programmed during system or car manufacturing.
Attopsemi’s I-fuse is a innovative “non-destructive” fuse technology that is programmed below the thermal runaway and above the electro-migration (EM) threshold. This is different than other fuse technologies which are using a destructive programming technique. Those destructive programming methods cannot be fully modeled and hence are not 100% reliable. On the contrary, I-fuse programming follows physics based on heat generation, heat dissipation, and electro-migration. The reliability of Attopsemi’s I-fuse is hence guaranteed by physics.
Attopsemi I-fuse technology can solve the OTP testability problem entirely. I-fuse programming is based electro-migration as a resulted of heat. If an unprogrammed I-fuse bit is tested, for example, below 400 ohm, this I-fuse can certainly produce enough heat to guarantee it is programmable. Furthermore, as the I-fuse program method will be established at prototype phase, the I-fuse programming yield can be estimated very accurately, and the program yield can be nearly 100%. Finally, every I-fuse functional block, such as the I-fuse bit-cell, the array, the X/Y-decoder, the sense amplifier, the control logic, and the program circuits can be fully tested.
Automotive ICs always have a goal to achieve ZERO defect, which means no defect after shipping because of the high cost of field returns. Any defects should be fully detectable and screened away before shipping. Therefore, 100% testability is necessary to reach this goal, and only Attopsemi I-fuse, among all available embedded OTP memory technologies can achieve this goal.