11 patents with 105 claims are directed to stacked integrated circuit memory (page 3). Each claim requires a “substantially flexible” semiconductor substrate or circuit layers (pages 5-6). The specification teaches grinding to a thickness less than 50 μm and then polishing or smoothing where the thinned substrate is now a substantially flexible substrate (page 8). The claims indicate that thinning and polishing is one way to form a substantially flexible substrate (page 8). The claims recite substantially flexible in a broader context, implying other ways to make flexible (page 9). Other claims recite making flexible by polishing without the thinning or vice versa (page 9). The prosecution history shows argument that the “substantially” for substrate is taught by the thinning to 50 μm and then polishing or smoothing, which is a disclaimer of broader scope (pages 9-10). The prosecution history treats substantially flexible for the circuit layer more narrowly than for the substrate, requiring substantially flexible substrate and low tensile stress dielectric material (page 10). The substantially flexible substrate must also bend without breaking (page 11). Since the prior art does not suggest a way to use the low tensile stress dielectric material of one prior art reference with the substrate of another reference due to the complex formation process, the claims are not obvious (pages 11-18).
Hindsight: The specification was written in a way that directly related substantially flexible to various process requirements rather than physical property. Similarly, the prosecution history treated flexibility based on materials used rather than a physical property. The physical property of flexibility could have been described (e.g., amount of bend over a given length without breaking) instead to support “substantially flexible.”