512, and silicon dioxide layer 926. In the step shown FIGS. 6A and 6B, the silicon dioxide layer 926 has just been deposited and patterned to provide a hard mask over the device coupon and sidewalls, and the unmasked areas etched. The etch is stopped around 200 nm above the release layer surface.

FIGS. 7-10 show cross-sectional views of various manufacturing steps of the variant coupon wafer of FIG. 5A. In FIG. 7, an antireflective coating 508 is deposited over the exposed surfaces of the coupon wafer. Subsequently, as shown in FIG. 8, a photoresist 802 is deposited and patterned so that a portion of the bed of the channel surrounding the device coupon is exposed. An etch is then performed, the result of which is shown in FIG. 9. In contrast to the example discussed below, this etch is performed so that no ledges are provided around the perimeter of the device coupon. The etch exposes an upper surface of the release layer 514, whilst retaining the antireflective coating 508 both around the device coupon and also on the sidewall and upper surface of the remaining coupon wafer.

Next, as shown in FIG. 10, a grating (best seen in FIG. 25) is etched through the release layer 514 to expose portions of the substrate. FIG. 11A is a top-down view of a manufacturing step of the variant coupon wafer of FIG. 5A, and FIG. 11B is a cross-sectional view of FIG. 11A along the line A-A′. In this step, a photoresist 550 is patterned and defined so as to at least partially fill the channel surrounding the device coupon. In this example, a gap remains between the photoresist 550 fill and the sidewalls of the coupon wafer. In other examples, no gap remains and the photoresist 550 entirely fills the channel. FIG. 12A is a top-down view of a manufacturing step of the variant coupon wafer of FIG. 5A, and FIG. 12B is a cross-sectional view of FIG. 12A along the line A-A′. In this step, the dielectric tether 504 is deposited (e.g. via sputtering or evaporation deposition). In the example shown, because of the gap between the photoresist 550 and the sidewall, the dielectric tether 504 between the fill and the sidewall of the coupon wafer.

FIG. 13A is a top-down view of a manufacturing step of the variant coupon wafer of FIG. 5A, and FIG. 13B is a cross-sectional view of FIG. 13A along the line A-A′. In this step, a further photoresist 550 is provided to define the eventual dielectric tether. This is best seen in FIG. 13A, where the photoresist has a shape which substantially matches the geometry of the final dielectric tether. FIG. 14A is a top-down view of a manufacturing step of the variant coupon wafer of FIG. 5A, and FIG. 14B is a cross-sectional view of FIG. 14A along the line A-A′. In this step, the unmasked dielectric is etched, and then all photoresist removed. FIG. 15A is a top-down view of a final manufacturing step of the variant coupon wafer of FIG. 5A, and FIG. 15B is a cross-sectional view of FIG. 12A along the line A-A′. In this step, the release layer 514 is etched away so as to release the device coupon 510 from the substrate 502.

FIGS. 16-20B show perspective views of various manufacturing steps of a coupon wafer. Initial steps, not shown, include (i) forming the device coupon 110 in a manner known per se in the art; (ii) etching a facet onto the device coupon (this step is optional, and used when an angled facet as shown in FIG. 16 is desired); (iii) creating ledges 900 on three sides of the device coupon, as shown in FIG. 16, but not on the facet side of the device coupon (this step is also optional, as discussed above); (iv) perform an etch to expose the release layer 902; and (v) create a trench (e.g. a rectangular trench) and etch to the substrate 904. FIG. 17 shows a subsequent step, where antireflective coating 906 is deposited over the exposed surfaces of the coupon wafer. After this, in a step shown in FIG. 18, a photoresist 908 is spun onto the device coupon and then patterned to define the eventual tether and apertures 910 (providing a grating) through which the release layer will be exposed.

Next, the unmasked antireflective coating 906 is etched to expose the top of the release layer 902 and the photoresist is then removed. The result of this is shown in FIG. 19. The apertures, forming a grating, provide penetration points for an etchant used to remove the release layer 902. The antireflective coating still covers the facet of the device coupon, as well as the sidewalls. The area between the grating and the trench can be tapered if required to make the tethers locally weaker to facilitate better breaking during printing. FIGS. 20A and 20B show two options for a subsequent processing step. In the step shown in FIG. 20A, a photoresist 912 is patterned to cover the entire device coupon 110. In an alternative, shown in FIG. 20B, only the facet is covered in a photoresist 914. The photoresist in FIG. 20B minimises the risk of causing failure of the tethers by only imparting a minimal amount of force to the device coupon. Both photoresists function to protect the facet from wet etchant leakage in the active region and metal contact layer. After release, and before print, the photoresist is removed. As dielectric tethers are being used, the device coupon can be cleaned with IPA/acetone after release. As the resist is anchored to the substrate, it will provide support to the sample during release (e.g. from capillary forces).

FIGS. 21-28B show perspective views of various manufacturing steps of a variant coupon wafer. Where it shares like features with the manufacturing steps of the coupon wafer shown in FIGS. 16-20B, like features are indicated by like reference numerals. Initial steps, not shown, include (i) forming the device coupon 110 in a manner known per se in the art; (ii) etching a facet onto the device coupon (this step is optional, and used when an angled facet as shown in FIG. 21 is desired); (iii) creating ledges 900 on three sides of the device coupon, as shown in