| Single Chip Microcomputer, which also be called MCU (Micro Controller Unit), has some virtues like small volume, strong performance, low cost and good convenience. There are many applications in a lot of fields such as consumption electronics, auto electronics, industry controller and automatization. MC68HC (8)05PV8/A is belong to MOTOROLA MCU 68HC05 8bits family, and it is designed for low cost and system on chip which be used in auto electronics. Because of its application for auto, high reliability is need for the production. At the same time, for the EEPROM arrays embeded in the MCU, they need support many w/e cycles, and there are high voltage and high level electronic field stressing on the tunnel oxide, so the reliability of the EERPOM array is the key for the yield of production. In order to improve the yield of MC68HC (8)05PV8/A production, we analysis the effect for yield of process and procedure in production line, find the isuue, and adopt some project to resolve the issue: Firstly, we check the procedure in Burn-In and Final Test, and find the issue that Burn-In time is not exact, then we do some experiments, sample and calculate, finally get the exact Burn-In time with our experiment results. Secondly, in order to resolve the issue that many BIN2 rejects happened in Burn-In and most of them are not genuine rejects, we modify the Burn-In program, add BIN2 checker in it, so the BIN2 rejects are reduced and yield in Final Test has been improved. At last, some research on EEPROM theory and process have been done, some main reasons have been found which affect the porfermance of EEPROM, such as threshold voltage shift, internal reliability and breakdown problem. Some examples happened in production line have been anlysised. All of above have indicated that the quality of floating gate and tunnel oxide will have a strictness effect for reliability of device. The improvment about process have been discussed. |
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