Low Breakdown Voltage, Low Capacitance (Bi-directional) Side Fired Transient Voltage Suppressor
Publication Date: 2002-Apr-30
The IP.com Prior Art Database
Emerging new market electronic applications require over-voltage protection on the low value range (under 30 Volt) compatible with low capacitance values for low insertion losses on high frequency transmission lines. Thus, a bi-directional or unidirectional Transient Voltage Suppressor (TVS) device design having low Breakdown Voltage (BV) values, good surge capability and medium to high IH (holding current) levels with reasonable wafer manufacture-ability while remaining fully compliant with the most demanding customer specs concerning capacitance and surge requirements would be highly desirable. The invention solves the problems of prior art using a novel localized, low breakdown voltage zener region on the side of the cathode created by a relatively deep double diffused region to create a bulk low breakdown site. This creates a novel bi-directional or unidirectional transient voltage suppressor having on its gate (or gates) a small, heavily doped region pattern providing a low breakdown spot along one of the edges (side or corner) where a Vertical PNP (or NPN, Depending on Device Conductivity Wafer Type) is formed. Furthermore, the new diffused process (above) can be modified to provide gate dopant surface enhancement at anode and gate regions and at cathode shorting dots. The new structure of the invention produces a semiconductor structure having low electrical capacitance provided by the use of a high resistivity wafer and anode-gate profile.