Method for manufacturing a composite structure comprising a thin film of monocrystalline SIC on a carrier substrate of polycrystalline SIC
A method of fabricating a composite structure includes providing a c-SiC initial substrate, depositing a relatively thin p-SiC first layer on a front side of the initial substrate at a relatively high temperature, the first layer having a dopant concentration greater than 10 19 /cm 3 , forming a buried brittle plane in the initial substrate delineating a thin layer of single crystal SiC between the brittle plane and a front side of the initial substrate, depositing a relatively thick amorphous and/or polycrystalline SiC second layer on the first layer at a relatively low temperature, the second layer including dopants of the same type as those of the first layer, at a concentration greater than 10 19 /cm 3 , and depositing a p-SiC third layer on the second layer at a relatively high temperature. A separation along the buried brittle plane takes place during the deposition process.
1 . A method of fabricating a composite structure including a thin layer of single-crystal silicon carbide on a carrier substrate of polycrystalline silicon carbide, the method comprising:
providing an initial substrate of single-crystal silicon carbide;
depositing a first layer of polycrystalline silicon carbide over a front side of the initial substrate at a temperature above 1100° C., the first layer having a thickness less than 1 μm and a dopant concentration greater than 10 19 /cm 3 ;
implanting light ionic species through the first layer to form a buried brittle plane in the initial substrate, the thin layer being delineated between the buried brittle plane and the front side of the initial substrate;
depositing a second layer of amorphous and/or polycrystalline silicon carbide on the first layer at a temperature below 900° C., the second layer having a thickness greater than or equal to 10 μm and a concentration of dopants, of the same type as a type of dopants of the first layer, the concentration of dopants in the second layer being greater than 10 19 /cm 3 ;
depositing a third layer of polycrystalline silicon carbide on the second layer at a temperature above 1000° C., a separation along the buried brittle plane occurring during the deposition of the third layer, the first layer, second layer and third layer forming the carrier substrate of the composite substrate.
2 . The method of claim 1 , wherein the deposition of the first layer and the deposition of the third layer are carried out using chemical vapor deposition at a temperature between 1100° C. and 1600° C.
3 . The method of claim 2 , further comprising forming the first layer to have a dopant concentration greater than 5×10 19 /cm 3 .
4 . The method of claim 3 , wherein, upon completion of the deposition of the first layer, the first layer has a thickness between 50 nm and 500 nm.
5 . The method of claim 4 , further comprising, deoxidizing the front side of the initial substrate before the deposition of the first layer.
6 . The method of claim 5 , further comprising forming an intermediate layer on the front side of the initial substrate before the deposition of the first layer, and wherein the deposition of the first layer comprises depositing the first layer on the intermediate layer.
7 . The method of claim 6 , further comprising forming the intermediate layer to be a silicon layer.
8 . The method of claim 5 , wherein the deposition of the third layer comprises forming the third layer to have a thickness greater than or equal to 100 μm and a dopant concentration greater than 10 19 /cm 3 at least in a region of the third layer adjacent the second layer having a thickness of one-hundred microns.
9 . The method of claim 2 , wherein the deposition of the first layer and the deposition of the third layer are carried out using chemical vapor deposition at a temperature between 1200° C. and 1600° C.
10 . The method of claim 9 , wherein the deposition of the first layer and the deposition of the third layer are carried out using chemical vapor deposition at a temperature between 1200° C. and 1400° C.
11 . The method of claim 1 , further comprising forming the first layer to have a dopant concentration greater than 5×10 19 /cm 3 .
12 . The method of claim 1 , wherein, upon completion of the deposition of the first layer, the first layer has a thickness between 50 nm and 500 nm.
13 . The method of claim 12 , wherein, upon completion of the deposition of the first layer, the thickness of the first layer is between 50 nm and 200 nm.
14 . The method of claim 1 , further comprising deoxidizing the front side of the initial substrate before the deposition of the first layer.
15 . The method of claim 1 , further comprising forming an intermediate layer on the front side of the initial substrate before the deposition of the first layer, and wherein the deposition of the first layer comprises depositing the first layer on the intermediate layer.
16 . The method of claim 15 , further comprising forming the intermediate layer to be a silicon layer.
17 . The method of claim 1 , wherein the deposition of the third layer comprises forming the third layer to have a thickness greater than or equal to 100 μm and a dopant concentration greater than 10 19 /cm 3 at least in a region of the third layer adjacent the second layer having a thickness of one-hundred microns.