Etch stop layer system

A method of integrating a device or layer comprising:

• depositing a substantially relaxed graded layer of Si1-xGex;
• on a Si substrate;
• depositing a uniform etch-stop layer of substantially relaxed Si1-yGey on said graded buffer;
• and
• etching portions of said substrate and said graded buffer in order to release said etch-stop layer.

A method of integrating a device or layer comprising:

• depositing a substantially relaxed graded layer of Si1-xGex on a Si substrate;
• depositing a uniform first etch-stop layer of substantially relaxed Si1-yGey on said graded buffer;
• depositing a second etch-stop layer of strained Si1-xGex;
• depositing a substantially relaxed Si1-wGew layer;
• etching portions of said substrate and said graded buffer in order to release said first etch-stop layer;
• and
• etching portions of said residual graded buffer in order to release the second etch-stop Si1-zGez layer.

(New) A semiconductor structure, comprising:

• a layer structure including:
• a uniform etch-stop layer;
• and
• a strained layer disposed over the uniform etch-stop layer, and
• an insulator layer disposed over the layer structure,
• wherein the uniform etch-stop layer has a relative etch rate which is less than approximately the relative etch rate of Si doped with 7×1019 boron atoms/cm3.

(New) A semiconductor structure, comprising:

• a first uniform etch-stop layer;
• a second etch-stop layer disposed over the uniform etch-stop layer;
• and
• a substantially relaxed layer disposed over the second etch-stop layer,
• wherein the first uniform etch-stop layer has a relative etch rate which is less than approximately the relative etch rate of Si doped with 7×1019 boron atoms/cm3.

(New) A method for forming a semiconductor structure, the method comprising:

• forming a uniform etch-stop layer;
• providing a handle wafer;
• and
• bonding the uniform etch-stop layer to the handle wafer,
• wherein said uniform etch-stop layer has a relative etch rate which is less than approximately the relative etch rate of Si doped with 7×1019 boron atoms/cm3.

(New) A method for forming a semiconductor structure, the method comprising:

• providing a first substrate;
• and
• forming a layer structure over the first substrate by:
• forming a uniform etch-stop layer over the first substrate;
• and
• forming a strained layer over the uniform etch-stop layer,
• wherein the uniform etch-stop layer has a relative etch rate which is less than approximately the relative etch rate of Si doped with 7×1019 boron atoms/cm3.

(New) A method for forming a semiconductor structure, the method comprising:

• forming a first uniform etch-stop layer;
• forming a second etch-stop layer over the uniform etch-stop layer;
• and
• forming a substantially relaxed layer over the second etch-stop layer, wherein the first uniform etch-stop layer has a relative etch rate which is less than approximately the relative etch rate of Si doped with 7×1019 boron atoms/cm3.

(New) A method for forming a semiconductor structure, the method comprising:

• providing a first substrate;
• forming a layer structure on the first substrate by:
• forming a substantially relaxed graded layer on the first substrate;
• and
• forming a uniform etch-stop layer on the graded layer;
• and
• releasing the etch-stop layer by removing at least a portion of the substrate and at least a portion of the graded layer,