Ferroelectric device and meethod for manufacturing same

Patent metadata

Field	Value
Publication number	US-2016247932-A1
Application number	US-201414903769-A
Country	US
Kind code	A1
Filing date	Jul 24, 2014
Priority date	Jul 25, 2013
Publication date	Aug 25, 2016
Grant date	—

Abstract

A ferroelectric device and a manufacturing method are provided. While holding a nonvolatile memory retention capability and a multiple rewriting endurance as the distinctive features of a ferroelectric device, the disclosed ferroelectric device is wider in memory window and more adaptively made microfiner than a conventional ferroelectric device that has used a ferroelectric mainly constituted of Sr—Bi—Ta—O as an oxide of strontium, bismuth and tantalum. Directly on or with intermediary of an insulator on a semiconductor there are layered a first ferroelectric and a conductor to form a gate stack, the first ferroelectric being mainly constituted of Sr—Ca—Bi—Ta—O as an oxide of strontium, calcium, bismuth and tantalum and being built up by a metal organic vapor deposition technique from a suitable film-forming raw material. The gate stack is heat-treated to cause the first ferroelectric to develop its ferroelectricity.

First claim

1 . A method of making a ferroelectric device having a semiconductor on which is had a multi-layered structure having an insulator, a ferroelectric and a conductor built up in this order or a multi-layered structure having a ferroelectric and a conductor built up in this order, the method comprising making a layer of said ferroelectric by a metal organic chemical vapor deposition process which comprises the steps of: preparing a raw material liquid solution having complex compounds each dissolved in a solvent, the complex compounds containing strontium, calcium, bismuth and tantalum; dispersing the raw material liquid solution into a carrier gas to form a raw material gaseous medium in a state of gas and liquid two phases; introducing the raw material gaseous medium while in the state of gas and liquid two phases into a vaporizing chamber to form a vapor thereof; and introducing the vapor into a film forming chamber.

2 . A method of making a ferroelectric device having a semiconductor on which is had a gate stack comprising layers of an insulator, a first ferroelectric and a conductor built up in this order or a gate stack comprising layers of a first ferroelectric and a conductor built up in this order, the method comprising: the step in which layers of a second ferroelectric and an insulator that has a dielectric constant of not more than 10 are built up in this order so that the second ferroelectric may lie in contact with at least the first ferroelectric on a side face of said gate stack; and the step of thereafter heat-treating said gate stack.

3 . A method of making a ferroelectric device having a semiconductor on which is formed a gate stack comprising layers of an insulator, a first ferroelectric and a conductor built up in this order or a gate stack comprising layers of a first ferroelectric and a conductor built up in this order, the method comprising the step in which a layer of a second ferroelectric mainly constituted of an oxide of strontium, calcium, bismuth and tantalum is formed by a metal organic chemical vapor deposition process so as to lie in contact with at least the first ferroelectric on a side face of said gate stack.

4 . A method of making a ferroelectric device as set forth in claim 2 , wherein the layer of said second ferroelectric has a thickness of not more than 100 nanometers.

5 . A method of making a ferroelectric device as set forth in claim 4 , wherein the layer of said second ferroelectric has a thickness of not more than 10 nanometers.

6 . A method of making a ferroelectric device as set forth in claim 2 , wherein said second ferroelectric is made by a metal organic chemical vapor deposition process which comprises: preparing a raw material liquid solution having complex compounds each dissolved in a solvent, the complex compounds containing strontium, calcium, bismuth and tantalum; dispersing the raw material liquid solution into a carrier gas to form a raw material gaseous medium in a state of gas and liquid two phases; introducing the raw material gaseous medium while in the state of gas and liquid two phases into a vaporizing chamber to form a vapor thereof; and introducing the vapor into a film forming chamber.

7 . A method of making a ferroelectric device as set forth in claim 2 , wherein of said layer of the second ferroelectric formed, a portion on the side face of said gate stack is left and a portion on a non-gate surface area of said semiconductor and other than that on which said gate stack is formed is removed in which state a source and a drain region are thereafter formed on the surface of said semiconductor.

8 . A method of making a ferroelectric device as set forth in claim 7 , wherein removal of said portion of the layer of the second ferroelectric is effected without masking or masklessly.

9 . A method of making a ferroelectric device as set forth in claim 7 wherein removal of said portion of said layer of the second ferroelectric on the semiconductor surface area is effected by an RIE technique.

10 . A method of making a ferroelectric device as set forth in claim 2 , wherein a said complex compound that contains calcium is: Ca[Ta(OC 2 H 5 ) 5 (OC 2 H 4 OCH 3 )] 2 or Ca(C 11 H 19 O 2 ) 2 .

11 . A method of making a ferroelectric device as set forth in claim 1 , wherein first ferroelectric is mainly composed of an oxide of strontium, calcium, bismuth and tantalum and has a proportion of strontium to calcium of 1−x:x wherein x is not more than 0.5.

12 . A method of making a ferroelectric device as set forth in claim 2 , wherein said second ferroelectric is mainly composed of an oxide of strontium, calcium, bismuth and tantalum and has a proportion of strontium to calcium of 1−x:x wherein x is not more than 0.5.

13 . A method of making a ferroelectric device as set forth in claim 1 , wherein the device has a gate length of not more than 200 nm.

14 . A ferroelectric device, comprising a semiconductor on which is had a multi-layered structure having an insulator, a ferroelectric and a conductor built up in this order or a multi-layered structure having a ferroelectric and a conductor built up in this order, said ferroelectric being a ferroelectric made by a metal organic chemical vapor deposition technique, wherein said metal organic chemical vapor deposition technique comprises: preparing a raw material liquid solution having complex compounds each dissolved in a solvent, the complex compounds containing strontium, calcium, bismuth and tantalum; dispersing the raw material liquid solution into a carrier gas to form a raw material gaseous medium in a state of gas and liquid two phases; introducing the raw material gaseous medium while in the state of gas and liquid two phases into a vaporizing chamber to form a vapor thereof; and introducing the vapor into a film forming chamber.

15 . A ferroelectric device, comprising a semiconductor on which is had a gate stack comprising layers of an insulator, a first ferroelectric and a conductor built up in this order or a gate stack comprising a first ferroelectric and a conductor built up in this order; and that layers of a second ferroelectric and an insulator that has a dielectric constant of not more than are built up in this order so that the second ferroelectric may lie in contact with at least the first ferroelectric on a side face of said gate stack, the said gate stack formed with said layers of the second ferroelectric and the insulator that has a dielectric constant of not more than 10 being thereafter heat-treated.

16 . A ferroelectric device, comprising a semiconductor on which is had a gate stack comprising layers of an insulator, a first ferroelectric and a conductor built up in this order or a gate stack comprising layers of a first ferroelectric and a conductor built up in this order; that a layer of a second ferroelectric is built up so as to lie in contact with at least the first ferroelectric on a side face of said gate stack; and that the layer of said second ferroelectric is mainly constituted of an oxide of strontium, calcium, bismuth and tantalum, said oxide being made by a metal organic chemical vapor deposition technique.

17 . A ferroelectric device as set forth in claim 15 wherein of the layer of said second ferroelectric formed, a portion on the side face of said gate stack is left and a portion on a non-gate surface area of said semiconductor and other than that on which said gate stack is formed is removed in which state a source and a drain region are thereafter formed on the surface of said semiconductor.

18 . A ferroelectric device as set forth i

Assignees

• Nat Inst Advanced Ind Science & Tech
• Wacom R&D Corp

Inventors

• Sakai Shigeki
• Takahashi Mitsue
• Kusuhara Masaki
• Toda Masayuki
• Umeda Masaru

Classifications

• H10P14/69398

  the material having a perovskite structure, e.g. BaTiO3 · CPC title

• H10P14/6334

  using decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition (deposition by physical ablation of a target H10P14/6329) · CPC title

• C23C16/40

  Oxides · CPC title

• H10D30/701 Primary

  IGFETs having ferroelectric gate insulators, e.g. ferroelectric FETs · CPC title

• H10D30/0415 Primary

  of FETs having ferroelectric gate insulators · CPC title