Semiconductor structure exhibiting reduced leakage current and method of fabricating same

• US 7,045,815 B2
• Filed: 07/30/2002
• Issued: 05/16/2006
• Est. Priority Date: 04/02/2001
• Status: Expired due to Term

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Inventors: Droopad, Ravindranath, Yu, Zhiyi
• Primary Examiner(s): Everhart, Caridad
• Application Number:
  US10/207,210
• Publication Number:
  US 20020187600A1
• Time in Patent Office: 1,386 Days
• Field of Search: 438/481, 438/785, 438/778, 438/761, 438/763, 438/787, 257/43, 257/632, 257/635
• US Class Current: 257/43
• CPC Class Codes: H01L 21/28194 by deposition, e.g. evaporation, ALD, CVD, sputtering, laser deposition H01L21/28202 takes precedence
• CPC Class Codes: H01L 29/513 the variation being perpendicular to the channel plane
• CPC Class Codes: H01L 29/517 the insulating material comprising a metallic compound, e.g. metal oxide, metal silicate H01L29/518 takes precedence

Abstract

A semiconductor structure exhibiting reduced leakage current is formed of a monocrystalline substrate (101) and a strained-layer heterostructure (105). The strained-layer heterostructure has a first layer (102) formed of a first monocrystalline oxide material having a first lattice constant and a second layer (104) formed of a second monocrystalline oxide material overlying the first layer and having a second lattice constant. The second lattice constant is different from the first lattice constant. The second layer creates strain within the oxide material layers, at the interface between the first and second oxide material layers of the heterostructure, and at the interface of the substrate and the first layer, which changes the energy band offset at the interface of the substrate and the first layer.

Claims

1. A semiconductor structure exhibiting reduced leakage current comprising:

a monocrystalline silicon substrate;

an amorphous oxide material in contact with the monocrystalline silicon substrate; and

a strained-layer heterostructure overlying said substrate, said heterostructure having;

a first layer comprising a first monocrystalline oxide material having a first lattice constant selected from the group consisting of alkaline earth metal titanates, alkaline earth metal zirconates, alkaline earth metal hafnates, alkaline earth metal tantalates, alkaline earth metal ruthenates, alkaline earth metal niobates, alkaline earth metal vanadates, alkaline earth metal tin-based perovskites, lanthanum aluminate, lanthanum scandium oxide, gadolinium oxide and mixtures thereof contacting the amorphous oxide material; and

a second layer comprising a second monocrystalline oxide material overlying said first layer and having a second lattice constant, wherein said second lattice constant is different from said first lattice constant,

wherein a strain is effected at least at one of an interface of said strained layer heterostructure and said substrate, an interface between said first layer and said second layer, and within said first layer and said second layer, and

wherein said substrate comprises a (001) semiconductor material having an orientation from about 2 degrees to about 6 degrees offset toward the (110) direction.

2. The semiconductor structure of claim 1, wherein said strained-layer heterostructure further comprises alternating first strained layers and second strained layers, wherein said alternating first and second strained layers overlie said second layer, and wherein said first strained layers comprise said first monocrystalline oxide material and said second strained layers comprise said second monocrystalline oxide material.

3. The semiconductor structure of claim 1, wherein said first layer has a thickness ranging from approximately one monolayer to approximately 100 angstroms.

4. The semiconductor structure of claim 1, wherein said second layer has a thickness ranging from approximately one monolayer to approximately 100 angstroms.

5. The semiconductor structure of claim 1, wherein said second lattice constant is greater than said first lattice constant.

6. The semiconductor structure of claim 1, wherein said first layer comprises Sr_xBa_1-xTiO₃, wherein x ranges from 0 to 1.

7. The semiconductor structure of claim 6, wherein said second layer comprises Sr_yBa_1-yTiO₃, where y is not equal to x.

8. The semiconductor structure of claim 1, wherein said second layer comprises a monocrystalline oxide material selected from the group consisting of alkaline earth metal titanates, alkaline earth metal zirconates, alkaline earth metal haihates, alkaline earth metal tantalates, alkaline earth metal ruthenates, alkaline earth metal niobates, alkaline earth metal vanadates, perovskite oxides such as alkaline earth metal tin-based perovskites, lanthanum aluminate, lanthanum scandium oxide, and gadolinium oxide.

9. The semiconductor structure of 1, wherein said strained-layer heterostructure further comprises a third layer formed of monocrystalline oxide material overlying said second layer and having a third lattice constant, wherein said third lattice constant is different from said second lattice constant.

10. The semiconductor structure of claim 9, wherein said third lattice constant is approximately equal to said first lattice constant.

11. The semiconductor structure of claim 9, wherein said third lattice constant is greater than said second lattice constant.