Pseudo-substrate with improved efficiency of usage of single crystal material
AssigneeSoitec
InventorsFabrice Letertre, Oleg Kononchuk
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Abstract
The invention relates to a method for fabricating a pseudo-substrate comprising the steps of providing a single crystal ingot, providing a handle substrate, cutting a thin slice from the single crystal ingot, and attaching the thin slice to the handle substrate to form a pseudo-substrate. According to the invention, the thickness of the thin slice is substantially equal or inferior to a critical thickness below which the slice, if taken alone, is no longer mechanically stable. The invention further relates to a semiconductor structure.
Claims23
A method for fabricating at least one pseudo-substrate, comprising:
- cutting a thin piezoelectric layer from a single crystal ingot comprising a piezoelectric material, to provide the thin piezoelectric layer comprising a first rough cut surface and a second surface opposite to the first rough cut surface of the single crystal ingot comprising a rough cut surface;
- providing a bonding layer on the first rough cut surface of the thin piezoelectric layer without polishing the first rough cut surface of the thin piezoelectric layer, the bonding layer comprising a front surface and a back surface, the front surface of the bonding layer adhering to the first rough cut surface of the thin piezoelectric layer;
- and
- bonding the back surface of the bonding layer to a handle substrate without polishing the back surface of the bonding layer prior to the bonding,
- wherein the handle substrate has a matching coefficient of thermal expansion with respect to the thin piezoelectric layer, and
- wherein a thickness of the thin piezoelectric layer is 300 μm or less.
A method for fabricating a structure comprising a layer of piezoelectric material on a final substrate, the method comprising:
- providing a pseudo-substrate, including:
- cutting a thin piezoelectric layer from a single crystal ingot comprising a piezoelectric material, the thin piezoelectric layer comprising a first rough surface;
- providing a bonding layer on the first rough surface of the thin piezoelectric layer without polishing the first rough surface of the thin piezoelectric layer, the bonding layer comprising a front surface and a back surface, the front surface of the bonding layer adhering to the first rough surface of the thin piezoelectric layer;
- and
- bonding the back surface of the bonding layer to a handle substrate without polishing the back surface of the bonding layer prior to the bonding;
- bonding the piezoelectric layer of the pseudo-substrate to the final substrate;
- and
- removing the handle substrate of the pseudo-substrate from the piezoelectric layer after bonding the piezoelectric layer of the pseudo-substrate to the final substrate.
Dependencies are inferred from the claim text.