Single crystalline silicon stack formation and bonding to a CMOS wafer
Systems, methods, and apparatus are provided for single crystalline silicon stack formation and bonding to a complimentary metal oxide semiconductor (CMOS) wafer for formation of vertical three dimensional (3D) memory. An example method for forming arrays of vertically stacked layers for formation of memory cells includes providing a silicon substrate, forming a layer of single crystal silicon germanium onto a surface of the substrate, epitaxially growing the silicon germanium to form a thicker silicon germanium layer, forming a layer of single crystal silicon onto a surface of the silicon germanium, epitaxially growing the silicon germanium to form a thicker silicon layer, and forming, in repeating iterations, layers of silicon germanium and silicon to form a vertical stack of alternating silicon and silicon germanium layers.
1. A device, comprising:
a number of CMOS components formed on a first substrate;
a second substrate attached to the first substrate, wherein the second substrate comprises:
a first layer of single crystal silicon germanium formed on a surface of the second substrate;
a first layer of single crystal silicon formed on a surface of the single crystal silicon germanium; and
repeating iterations of layers of single crystal silicon germanium and single crystal silicon forming a vertical stack of alternating single crystal silicon and single crystal silicon germanium layers.
2. The device of claim 1 , further comprising:
a layer of bonding material providing the attachment between a surface of the first substrate and the first layer of single crystal silicon germanium.
3. The device of claim 2 , wherein the layer of bonding material is a dielectric material.
4. The device of claim 1 , further comprising:
at least one layer of the vertical stack having a word line defined in the layer.
5. The device of claim 1 , further comprising:
at least one layer of the vertical stack having a digit line defined in the layer.
6. The device of claim 1 , wherein the vertical stack comprises a number of access devices and corresponding memory cells formed therein.
7. The device of claim 6 , wherein the memory cells are three dimensional (3D) dynamic random access memory (DRAM) cells.
8. The device of claim 6 , wherein the number of access devices comprise a single crystal silicon channel.