Process for ion implantation
The present invention relates to a substrate comprising an ion-implanted layer, for example a cation, wherein the ion implanted layer has a substantially uniform distribution of the implanted ions at a significantly greater depth than previously possible, to a well-defined and sharp boundary within the substrate. The invention further comprises said sub-strate wherein the substrate is a silicon based substrate, such as glass. The invention also comprises the use of said material as a waveguide and the use of said material in measurement devices.
1. A process for fabricating an ion-implanted layer in a substrate comprising silicate glass, the process comprising:
providing a target layer comprising a tellurite glass in a vacuum chamber at a reduced pressure;
providing said substrate in the vacuum chamber which includes a surface of the substrate in proximity to said target layer wherein the surface of the substrate is spaced from the target layer by a distance in the range 50 mm to 70 mm;
heating the substrate to a temperature in the range from 0.55 T g to 0.75 T g where T g is the glass transition temperature of the substrate; and,
directing pulses of incident radiation from a laser at the target layer thereby ablating material of the target layer with said incident radiation to produce therefrom a plume of the ablated target material capable of implanting into the heated substrate with the target layer and the substrate in oxygen gas at said reduced pressure within the range 80 mTorr to 90 mTorr, whereby said ablated material of said plume is implanted into the heated substrate by entering the heated substrate via the surface of the heated substrate such that a film of said ablated target material is not formed on the surface of the heated substrate, thereby forming a layer of implanted ions of said ablated target material within the heated substrate which extends from the surface of the heated substrate to a depth of at least 50 nm and which has a density of said implanted ions of said ablated target material of at least 10 21 ions cm −3 .
2. A process according to claim 1 wherein the laser is a Femtosecond laser.
3. A process according to claim 1 wherein said implanted ions of said layer of implanted ablated target material are arranged in a spatial distribution which is substantially uniform along a direction extending into the heated substrate from the surface of the heated substrate.
4. A process according to claim 1 wherein said layer of implanted ablated target material has a density of said implanted ions of at least 10 23 ions cm −3 .
5. A process according to claim 1 in which the depth of the implanted ions of said layer of implanted ablated target material is at least 200 nm.
6. A process according to claim 1 where the depth of the implanted ions of said layer of implanted ablated target material is at least 500 nm.
7. A process according to claim 1 wherein said implanted ions of said layer of implanted ablated target material are arranged in a spatial distribution which is substantially uniform along a direction extending into the heated substrate.
8. A process according to claim 1 wherein the layer of implanted ablated target material either:
(i) encompasses substantially the whole area of said surface of the heated substrate; or
(ii) comprises one or more zones of said surface of the heated substrate.
9. A process according to claim 1 wherein the layer of implanted ablated target material comprises one or more zones of said surface of the heated substrate wherein the zones comprise the same or different ions.
10. A process according to claim 1 wherein the implanted ions are cations.