Semiconductor device having semiconductor-on-insulator structure

Claim 2

A semiconductor-on-insulator structure comprising: a base substrate having a main surface; an insulator layer at least on the main surface of said base substrate and having a top surface, said insulator layer including impurities therein establishing a first fixed charge in said insulator layer, said impurities having a predetermined density distribution relative to the distance from the top surface of the insulator layer and the top surface of the insulator layer having an impurity density which corresponds approximately to the maximum impurity density in the predetermined density distribution; an active substrate of a semiconductor material and having a bottom surface bonded to and defining an interface with the top surface of the insulator layer, said active substrate having a second fixed charge at the interface of the insulator layer and said active substrate, said second fixed charge having a polarity opposite to that of said first fixed charge and a density corresponding to said maximum impurity density of said first charge; and at least one semiconductor element formed in a region of said active substrate at least above the first fixed charge of said base substrate.

Claim 3

The semiconductor-on-insulator structure as claimed in claim 1 wherein said first fixed charge is negative and said second fixed charge is positive.

Claim 4

The semiconductor-on-insulator structure as claimed in claim 1 wherein said insulator layer is made of a material selected from a group which includes silicon dioxide (SiO 2 ), and said impurities are selected from a group of elements including aluminum (Al), calcium (Ca), potassium (K) and tin (Sn).

Claim 5

The semiconductor-on-insulator structure as claimed in claim 3 wherein said active substrate is made of a material selected from a group which includes silicon (Si).

Claim 6

A semiconductor-on-insulator structure comprising: a base structure having a first main surface; a first insulator layer at least on the first main surface of said base substrate and having a top surface, said first insulator layer including impurities therein establishing a first fixed charge in said first insulator layer, said impurities having a predetermined density distribution relative to the distance from the top surface of the first insulator layer and the top surface portion of the first insulator layer having an impurity density which corresponds approximately to the maximum impurity density in the predetermined density distribution; an active substrate of a semiconductor material having a second main surface; a second insulator layer at least on the second main surface of said active substrate and having a bottom surface in contact with, and bonded to and defining an interface with the top surface of the first insulator layer, said active substrate having a second fixed charge at the interface of the second insulator layer and said active substrate, said second fixed charge having a polarity opposite to that of said first fixed charge and a density corresponding to the maximum impurity density of said first fixed charge; and at least one semiconductor element formed in a region of said active substrate at least above the first fixed charge of said base substrate.

Claim 7

A semiconductor-on-insulator structure comprising: a base structure having a first main surface; a first insulator layer at least on the first main surface of said base substrate and having a top surface, said first insulator layer including impurities therein establishing a first fixed charge in said first insulator layer, said impurities having a predetermined density distribution relative to the distance from the top surface of the first insulator layer and the top surface portion of the first insulator layer having an impurity density which corresponds approximately to the maximum impurity density in the predetermined density distribution; an active substrate of a semiconductor material having a second main surface; a second insulator layer at least on the second main surface of said active substrate and having a bottom surface in contact with, and bonded to and defining an interface with the top surface of the first insulator layer, said active substrate having a second fixed charge at the interface of the second insulator layer and said active substrate, said second fixed charge having a polarity opposite to that of said first fixed charge and a density corresponding to the maximum impurity density of said first fixed charge; and at least one semiconductor element formed in a region of said active substrate at least above the first fixed charge of said base substrate.

Claim 8

The semiconductor-on-insulator structure as claimed in claim 5 wherein said first fixed charge is positive and said second fixed charge is negative.

Claim 9

The semiconductor-on-insulator structure as claimed in claim 5 wherein said first and second insulator layers are made of a material selected from a group which includes silicon dioxide (SiO 2 ), and said impurities are selected from a group of elements including aluminum (Al), calcium (Ca), potassium (K) and tin (Sn).

Claim 10

The semiconductor-on-insulator structure as claimed in claim 7 wherein said active substrate is made of a material selected from a group which includes silicon (Si).