Patent ID: 8097080

Claim:
A method of separating single crystals, particularly of plates, wafers or parts thereof, comprising: pre-adjusting a crystallographic cleavage plane relative to a cleavage device; determining a stress intensity using at least one stress field; for the at least one stress field, determining an energy release rate G(α) dependent on a possible deflection angle from the cleavage plane upon crack propagation in a single crystal; generating the at least one stress field, wherein G(0)≧2γ e (0) and simultaneously at least one of the following conditions is satisfied:  ∂ G ∂ α  α = 0 ≤ 2 ⁢ β e h ⁢ ⁢ if ⁢ ⁢ ∂ 2 ⁢ G ∂ α 2 ≤ 0 ⁢ ⁢ or ( 2.1 )  ∂ G ∂ α  ≤ 2 ⁢ β e h ⁢ ∀ α ⁢ : ⁢ α 1 < α < α 2 , ( 2.2 ) wherein: α denotes the possible deflection angle from the cleavage plane upon crack propagation, α 1 , α 2 denotes a range of angles, in which the necessary condition for a crack propagation G(α)≧2γ e (α) is satisfied, G(α) denotes the mechanical-energy-release rate dependent on a deflection of the crack from the cleavage plane about angle α, γ e (0) denotes an effective surface energy of cleavage surface, γ e denotes an effective surface energy which depends from the direction, β e denotes an effective step energy (material specific), and h denotes a step height (material specific).