Back-to-back metal/semiconductor/metal (MSM) Schottky diode

Abstract

A method is provided for forming a metal / semiconductor / metal (MSM) back-to-back Schottky diode from a silicon (Si) semiconductor. The method deposits a Si semiconductor layer between a bottom electrode and a top electrode, and forms a MSM diode having a threshold voltage, breakdown voltage, and on / off current ratio. The method is able to modify the threshold voltage, breakdown voltage, and on / off current ratio of the MSM diode in response to controlling the Si semiconductor layer thickness. Generally, both the threshold and breakdown voltage are increased in response to increasing the Si thickness. With respect to the on / off current ratio, there is an optimal thickness. The method is able to form an amorphous Si (a-Si) and polycrystalline Si (polySi) semiconductor layer using either chemical vapor deposition (CVD) or DC sputtering. The Si semiconductor can be doped with a Group V donor material, which decreases the threshold voltage and increases the breakdown voltage.

Description

[0001]This application is a reissue of U.S. patent application Ser. No. 12 / 234,663, filed Sep. 21, 2008 (now U.S. Pat. No. 7,968,419), entitled, BACK-TO-BACK METAL / SEMICONDUCTOR / METAL (MSM) SCHOTTKY DIODE which is a Divisional of a patent application entitled, METAL / SEMICONDUCTOR / METAL (MSM) BACK-TO-BACK SCHOTTKY DIODE, invented by Tingkai Li et al., Ser. No. 11 / 435,669, filed May 17, 2006 issued as U.S. Pat. No. 7,446,010; which is a Continuation-in-Part of a patent application entitled, MSM BINARY SWITCH MEMORY DEVICE, invented by Sheng Teng Hsu et al., Ser. No. 11 / 184,660, filed Jul. 18, 2005 issued as U.S. Pat. No. 7,303,971. This application is a Continuation-in-Part of a patent application entitled, METAL / ZnOx / METAL CURRENT LIMITER, invented by Tingkai Li et al., Ser. No. 11 / 216,398, filed Aug. 31, 2005 now U.S. Pat. No. 7,271,081. This application is a Continuation-in-Part of a patent application entitled, CROSSPOINT RESISTOR MEMORY DEVICE WITH BACK-TO-BACK SCHOTTKY DIODE, in...

AI Technical Summary

Benefits of technology

The patent describes a back-to-back diode device that allows current to flow in both directions, but not at lower voltages. This device can be added to a resistance memory cell to allow for higher voltage programming without interfering with lower voltage read operations. It also mentions that this device addresses issues of read disturbance, which occurs when electric current flows from a selected word line to an unselected word line. The patent describes a method for making a MSM back-to-back Schottky diode using a silicon semiconductor layer and controlling its thickness to modify its threshold and breakdown voltages, as well as its on / off current ratio. The technical effect is the improved performance of resistance memory arrays with reduced read disturbance and improved programmability.

Problems solved by technology

Many conventional cross-point resistor memory arrays suffer from read disturbance problems, as electric current flows from a selected word line, through a selected memory cell to a bit line, and then into unselected word lines which cross over the bit line.

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