Method for forming silicon wells of different crystallographic orientations
View Patent ↗A method for manufacturing silicon wells of various crystallographic orientations in a silicon support, including the steps of: forming a silicon layer having a first orientation on a silicon substrate having a second orientation; forming insulating walls, defining wells extend at least down to the border between the silicon substrate and the silicon layer; performing, in first wells, a chemical vapor etch (CVE) of the silicon layer by means of hydrochloric acid, in an epitaxy reactor, at a temperature ranging between 700° C. and 950° C.; and performing, in the first wells, a vapor-phase epitaxy on the silicon substrate in the presence of a precursor of silicon and hydrochloric acid, at a temperature ranging between 700° C. and 900° C. and up to the upper surface of the silicon layer.
1. A method for manufacturing silicon wells of two crystallographic orientations and having smooth upper surfaces, in a silicon support, comprising the successive steps of:
forming a silicon layer having a first crystallographic orientation on a silicon substrate having a second crystallographic orientation;
forming insulating walls which extend at least down to a border between the silicon substrate and the silicon layer, the insulating walls defining wells;
performing, in at least one well, a chemical vapor etch of the silicon layer by means of hydrochloric acid, in an epitaxy reactor, at a temperature ranging between 700° C. and 950° C.; and
performing, in the at least one well, a vapor-phase epitaxy on the silicon substrate in the presence of a precursor of silicon and hydrochloric acid, at a temperature ranging between 700° C. and 900° C. and up to the upper surface of the silicon layer, this epitaxy being performed in said epitaxy reactor.
2. The method of claim 1 , wherein the etch and epitaxy steps are carried out at a pressure ranging between 600 Pa and 11,000 Pa.
3. The method of claim 1 , wherein the first crystallographic orientation has a (110) orientation and the second crystallographic orientation has a (100) orientation.
4. The method of claim 1 , wherein the silicon precursor belongs to the group consisting essentially of trichlorosilane, dichlorosilane, and silicon hydrides.
5. The method of claim 1 , wherein performing, in at least one well, a chemical vapor etch of the silicon layer by means of hydrochloric acid, in an epitaxy reactor, at a temperature ranging between 700° C. and 950° C. comprises performing in the at least one well, a chemical vapor etch of the silicon layer by means of hydrochloric acid, in the epitaxy reactor, at a temperature ranging between 700° C. and 900° C.
6. A method for manufacturing silicon wells of two crystallographic orientations and having smooth upper surfaces, in a silicon support, the method comprising:
forming a silicon layer having a first crystallographic orientation on a silicon substrate;
forming insulating walls which extend at least down to a border between the silicon substrate and the silicon layer, the insulating walls defining wells;
etching a portion of the silicon layer by means of hydrochloric acid, in an epitaxy reactor, at a temperature ranging between 700° C. and 950° C.; and
performing, in at least one well, a vapor-phase epitaxy on the silicon substrate at a temperature ranging between 700° C. and 900° C., this epitaxy being performed in said epitaxy reactor.
7. A method for manufacturing silicon wells of two crystallographic orientations in a silicon support, the method comprising:
forming a silicon layer having a first crystallographic orientation on a silicon substrate;
forming insulating walls that extend at least down to a border between the silicon substrate and the silicon layer;
in an epitaxy reactor:
etching at least one well in the silicon layer; and
epitaxially growing silicon in the at least one well such that an upper surface of a resulting epitaxy layer remains planar.
8. The method of claim 7 , further comprising passivating insulating wall surfaces so that growth is only performed from a surface of the silicon substrate.
9. The method of claim 8 , wherein passivating the insulating wall surfaces comprises flowing hydrochloric acid during epitaxy growth.
10. The method of claim 9 , further comprising flowing one of Silicon hydride, trichlorosilane, and dichlorosilane during epitaxy growth.
11. The method of claim 10 , wherein flowing one of silicon hydride, trichlorosilane and dichlorosilane comprises flowing silicon hydride, trichlorosilane and dichlorosilane at a temperature ranging between 700° C. and 900° C.
12. The method of claim 8 , further comprising flowing one of silicon hydride, trichlorosilane, and dichlorosilane during epitaxy growth.
13. The method of claim 12 , wherein flowing one of silicon hydride, trichlorosilane and dichlorosilane comprises flowing silicon hydride, trichlorosilane and dichlorosilane at a temperature ranging between 700° C. and 900° C.
14. The method of claim 7 , wherein after epitaxy growth, a first well comprises silicon of the first crystallographic orientation and a second well comprises a second crystallographic orientation.
15. The method of claim 7 , wherein etching comprises performing a chemical vapor etch using hydrochloric acid with hydrogen being used as a carrier gas.
16. The method of claim 15 , wherein etching is performed at a temperature ranging between 700° C. and 950° C.
17. The method of claim 16 , wherein etching is performed at a pressure ranging between 600 Pa and 11,000 Pa.
18. The method of claim 7 , wherein etching comprises etching in a manner to avoid etching insulating walls to maintain a planar character of the walls.