Mechanical locking sputtering target bonding method and target assemblies produced thereby

A method of forming a bond in a sputtering assembly, the method comprising:

• forming first projections on a bonding surface of a sputtering target, the first projections extending circumferentially to form rings on the sputtering target and radially spaced from adjacent first projections by first recesses, each first projection having a first height;
• forming second projections on a bonding surface of a backing plate, the second projections extending circumferentially to form rings on the backing plate and radially spaced from adjacent second projections by second recesses, each second projection having a second height, and the backing plate having a greater hardness than the sputtering target;
• aligning the sputtering target and the backing plate so that the first projections fit within the second recesses and the second projections fit within the first recesses to form an assembly, and wherein a stop projection extends from backing plate at the periphery, the stop projection having a height greater than the first height of each of the first projections and the second height of each of the second projections, wherein after aligning the sputtering target and the backing plate, the stop projection is immediately adjacent to and radially outward of at least a portion the sputtering target;
• after aligning the sputtering target and the backing plate, forming a bond between the stop projection and the sputtering target under vacuum, wherein after forming the bond, each first projection has the first height, and each second projection has the second height;
• and
• applying pressure to the assembly to deform at least one of the first projections and the second projections to form an interlock bond between the sputtering target and the backing plate, wherein the interlock bond is void-free.