Stress-free composite substrate and method of manufacturing such a composite substrate
A stress free composite substrate is disclosed comprising a carrier ( 2 ) composed of a carrier material, a first layer ( 12 ) composed of a first material, and an intermediate layer composed of a second material being located between the carrier ( 2 ) and the first layer ( 12 ), wherein the first material has a dilatation behavior being substantially the same as that of the carrier material, and having a dilatation mismatch with the second material, the intermediate layer ( 6 ) having structures ( 8 ) of second material for absorbing stress originating from the dilatation mismatch. A method for making such a stress free composite substrate is also disclosed.
1 . A composite substrate comprising
a carrier composed of a carrier material,
a first layer composed of a first material, and
an intermediate layer composed of a second material being located between the carrier and the first layer, wherein the first material has a dilatation behavior being substantially the same as that of the carrier material, and having a dilatation mismatch with the second material, the intermediate layer having structures of second material for absorbing stress originating from the dilatation mismatch.
2 . A composite substrate according to claim 1 , wherein the intermediate layer has a thickness, and the structures extend through the thickness of the intermediate layer.
3 . A composite substrate according to claim 1 , wherein the structures further extend into the carrier.
4 . A composite substrate according to claim 1 , wherein the carrier material is the same as the first material.
5 . A composite substrate according to claim 1 , wherein the carrier material and the first material are semiconductors.
6 . A composite substrate according to claim 1 , wherein the second material is an electrically insulating material.
7 . A composite substrate according to claim 1 , the intermediate layer lying in a plane, wherein the dimensions of the structures in the plane of the intermediate layer are less than a centimeter.
8 . A composite substrate according to claim 1 , wherein the carrier lies in a plane and wherein the structures have a line-symmetric shape in a cross-section perpendicular to the plane of the carrier.
9 . A composite substrate according to claim 1 , wherein the carrier lies in a plane and wherein the structures have a circular, square, rectangular or rhombic shape in a cross-section parallel to the plane of the carrier.
10 . A composite substrate according to claim 1 , wherein the composite substrate is a silicon-on-insulator wafer.
11 . A method to relieve stress in a composite substrate, comprising:
providing a carrier, composed of a carrier material, with on top thereof an intermediate layer of a second material,
forming in the intermediate layer structures which extend through the intermediate layer,
bonding on the intermediate layer a first substrate of a first material having a dilatation behavior being substantially the same as that of the carrier material.
12 . A method according to claim 11 , in which the structures are formed into the carrier.
13 . A method according to claim 11 , wherein the forming of the structures is executed by integrally patterning the structures over the intermediate layer.
14 . A method according to claim 11 , wherein the forming of the structures is executed by locally patterning the structures in clusters over the intermediate layer.
15 . A method according to claim 11 , wherein the patterning comprises applying millimeter, micrometer or nanometer structural texturing.
16 . A method according to claim 11 , wherein the patterning comprises applying imprint lithography.
17 . A method according to claim 11 , wherein the intermediate layer lies in a plane, and wherein the forming of the structures is such that the dimensions of the structures in the plane of the intermediate layer are less than a centimeter.
18 . A method according to claim 11 , wherein the carrier lies in a plane, and wherein the forming of the structures is such that the structures have a line-symmetric shape in a cross-section perpendicular to the plane of the carrier.
19 . A method according to claim 11 , wherein the carrier lies in a plane, and wherein the forming of the structures is such that the structures have a circular, square, rectangular or rhombic shape in a cross-section parallel to the plane of the carrier.
20 . Use of the method as recited claim 11 , for making a silicon-on-insulator substrate.