Large angle channel threshold implant for improving reverse narrow width effect

摘要

The present invention provides a method of manufacturing MOS device having threshold voltage adjustment region 28 ormed using a large angled implant. The invention's angled implant serves as both (a) a Vt adjustment I/I and (b) a Channel stop I/I by (1) increasing the threshold voltage (Vt) and (2) reducing the leakage current. The method comprises forming spaced field oxide regions having bird's beaks on a semiconductor substrate. A field implant is performed using the spaced field oxide regions as an implant mask formed a deep channel stop region 24. Next, a sacrificial oxide layer 20 is formed over the resultant surface. In a critical step, a threshold voltage adjustment region 28 is formed by performing a large angled implant of a p-type ions. The p-type ions into are implanted into the channel region 19 and under the bird's beak 18 such that the threshold voltage is higher under the bird's beak than in the channel region 19. A MOS transistor is then formed over the channel region. The large angled threshold voltage implant of the present invention eliminates the reverse narrow width effect (e.g., reduced threshold voltage (Vt) and increased leakage currents).