Method of forming a multilayer substrate comprising a layer of silicon and a layer of diamond having an optically finished (or a dense) silicon-diamond interface
A method of making a multilayer substrate, which can include a silicon layer having an optically finished surface and a chemical vapor deposition (CVD) grown diamond layer on the optically finished surface of the silicon layer. At the interface of the silicon layer and the diamond layer, the optically finished surface of the silicon layer can have a surface roughness (Ra)≤100 nm. A surface of the grown diamond layer opposite the silicon layer can be polished to an optical finish and a light management coating can be applied to the polished surface of the grown diamond layer opposite the silicon layer. A method of forming the multilayer substrate is also disclosed.
1. A method of forming a multilayer substrate, the multilayer substrate comprising a silicon layer having an optically finished surface and a multilayer chemical vapor deposition (CVD) grown diamond film on the optically finished surface of the silicon layer including nanodiamond particles between at least one pair of CVD layers, wherein at an interface of the silicon layer and the diamond film, the optically finished surface of the silicon layer has a surface roughness (Ra)≤100 nm, the method comprising:
(a) providing a silicon layer having the optically finished surface;
(b) following step (a), seeding the optically finished surface of the silicon layer with diamond particles;
(c) following step (b), CVD depositing a diamond layer on a diamond seeded optically finished surface of the silicon layer; and
(d) continue CVD depositing the diamond layer on the diamond seeded optically finished surface of the silicon layer until a minimum thickness of the diamond layer is deposited on the diamond seeded optically finished surface of the silicon layer.
2. The method of claim 1 , further including, between steps (c) and (d), the steps of:
(c1) stopping CVD depositing the diamond layer on the diamond seeded optically finished surface of the silicon layer; and
(c2) seeding the optically finished surface of the silicon layer including the CVD deposited diamond layer of step (c) with diamond particles.
3. The method of claim 1 , wherein:
the silicon layer of step (a) includes a substrate bonded to a side of the silicon layer opposite the optically finished surface; and
the substrate is thicker than the silicon layer.
4. The method of claim 1 , further including:
(e) polishing a surface of the diamond layer opposite the silicon layer to an optical finish.
5. The method of claim 4 , further including applying a light management coating on the polished surface of the diamond layer opposite the silicon layer.
6. The method of claim 1 , wherein the minimum thickness of step (d) is 10 microns.