Process for producing a layer arrangement, and layer arrangement for use as a dual gate field-effect transistor
View Patent ↗The invention relates to a process for producing a layer arrangement, in which, a porous silicon layer is formed as sacrificial layer on an auxiliary substrate, a first semiconductor layer is formed on the sacrificial layer, a first electrically insulating layer is formed on the first semiconductor layer, an electrically conductive layer is formed on the first electrically insulating layer, which electrically conductive layer is laterally patterned, the first electrically insulating layer, the sacrificial layer and the first semiconductor layer are jointly laterally patterned using the laterally patterned electrically conductive layer as a mask, a semiconductor structure is formed adjacent to side walls of the patterned sacrificial layer and of the patterned first semiconductor layer, a substrate is secured over the patterned electrically conductive layer, material of the auxiliary substrate is removed, so that the sacrificial layer is uncovered, the sacrificial layer is selectively removed, so as to form a trench, and a second electrically insulating layer is formed in the trench, then an electrically conductive structure is formed on this second electrically insulating layer.
1. A process for producing a layer arrangement, comprising the steps of:
forming a porous silicon layer as a sacrificial layer on an auxiliary substrate;
forming a first semiconductor layer on the sacrificial layer;
forming a first electrically insulating layer on the first semiconductor layer;
forming an electrically conductive layer on the first electrically insulating layer, wherein the electrically conductive layer is laterally patterned;
wherein the first electrically insulating layer, the sacrificial layer, and the first semiconductor layer are jointly patterned laterally using the laterally patterned electrically conductive layer as a mask;
forming a semiconductor structure adjacent to side walls of the patterned sacrificial layer and of the patterned first semiconductor layer;
securing a substrate over the patterned electrically conductive layer;
removing material of the auxiliary substrate, so that the sacrificial layer is uncovered;
selectively removing the sacrificial layer, so as to form a trench; and
forming a second electrically insulating layer in the trench, and forming an electrically conductive structure on this second electrically insulating layer.
2. The process as claimed in claim 1 , wherein the auxiliary substrate is a bulk semiconductor substrate.
3. The process as claimed in claim 1 , wherein the auxiliary substrate is a bulk silicon substrate.
4. The process as claimed in claim 1 , wherein the porous silicon layer is a silicon layer of a first porosity and a silicon layer of a second porosity arranged thereon, the first porosity being greater than the second porosity.
5. The process as claimed in claim 1 , wherein the first semiconductor layer is a single-crystal silicon layer.
6. The process as claimed in claim 1 , wherein the electrically conductive layer is a polycrystalline silicon layer.
7. The process as claimed in claim 1 , wherein the semiconductor structure is single-crystal silicon material.
8. The process as claimed in claim 1 , wherein the selective removal of the sacrificial layer is realized by means of an etching process, by means of which material of the sacrificial layer is removed selectively with respect to material of the semiconductor structure.
9. The process as claimed in claim 1 , wherein the material of the electrically conductive structure is polycrystalline silicon.
10. The process as claimed in claim 1 , further comprising the step of forming a second semiconductor layer between the auxiliary substrate and the sacrificial layer.
11. The process as claimed in claim 10 , wherein the second semiconductor layer is a p-doped silicon layer and an n-doped silicon layer arranged thereon.
12. The process as claimed in claim 11 , wherein the dopant concentration of the p-doped silicon layer is greater than the dopant concentration of the n-doped silicon layer.
13. The process as claimed in claim 12 , wherein the second semiconductor layer is a germanium-silicon layer and an n-doped silicon layer arranged thereon.
14. The process as claimed in claim 1 , wherein prior to the step of securing the substrate, further comprising the step of forming an electrically insulating structure with a planar surface on the layer sequence derived from the processed auxiliary substrate.
15. The process as claimed in claim 1 , wherein the substrate is secured by means of bonding.
16. The process as claimed in claim 1 , further comprising the step of applying a metallic material to the semiconductor structure and/or to the electrically conductive structure and/or to the laterally patterned electrically conductive layer.
17. The process as claimed in claim 1 , wherein the layer arrangement is designed as a dual gate field-effect transistor.
18. The process as claimed in claim 17 , wherein the first semiconductor layer is a channel region, the semiconductor structure is source/drain regions, the electrically conductive layer is a first gate electrode, the first electrically insulating layer is a first gate-insulating layer, the electrically conductive structure is a second gate electrode, and the second electrically insulating layer is a second gate-insulating layer.