Analysis of Dynamic RAM´s by Use of Alpha Irradiation

Alpha particles can cause soft errors in dynamic MOS-IC´s through their high ionization rate. This mechanism can be used to inject disturb charges into a device thus enabling determination of the internal integrity of the device. Applying this method the electrical quality, yield limiting factors, and reliability problems of 16K RAM´s were analyzed without restrictions upon the operating conditions of the devices. It can be distinguished between obvious device weaknesses, like unbalanced memory arrays and highly imperfect bit lines, or hidden weaknesses detectable only through statistical evaluations of the local distribution of soft errors. This work has been supported by the Federal Department of Research and Technology of the Federal Republic of Germany. The author alone is responsible for the content.