Wafer alignment features

A method of manufacturing optical elements, the method comprising:

• providing a first wafer having lower alignment features, comprising a first sloped lower alignment feature surface and a second sloped lower alignment feature surface;
• providing a second wafer comprising, on a replication side, at least one surface structure,
• the second wafer further comprising upper alignment features protruding, on the replication side, further than the at least one surface structure, wherein the upper alignment features comprise a first sloped upper alignment feature surface and a second sloped upper alignment feature surface;
• depositing liquid droplets on the first sloped lower alignment feature surface and the second sloped lower alignment feature surface of the first wafer and/or the first sloped upper alignment feature surface and the second sloped upper alignment feature surface of the second wafer;
• and
• aligning the first wafer and the second wafer with respect to each other and bringing the first wafer and the second wafer together, with liquid droplets between the first wafer and the second wafer,
• the first sloped lower alignment feature surface contacting the first sloped upper alignment feature surface and the second sloped lower alignment feature surface contacting the second sloped upper alignment feature surface through the liquid droplets, and thereby causing the first wafer to align with the second wafer by capillary action,
• wherein the lower alignment features are shaped such that distances between the lower alignment features and the upper alignment features depend on a contact angle between a liquid droplet of the liquid droplets and air outside of the lower alignment features and upper alignment features.