Abstract: A method of inspecting flatness of substrate is provided and includes providing a substrate. N first inspecting points are selected from the surface of the substrate along a first straight line, where the coordinate of the i-th first inspecting point is (Xi,Yi,Zi). By using a formula “ D = ? i = 1 N - 1 ? ( X i + 1 - X i ) 2 + ( Y i + 1 - Y i ) 2 + ( Z i + 1 - Z i ) 2 ” , a first measurement length D is calculated. By using a formula “F=(D?S)/S”, a first flatness index F is calculated. S is the horizontal distance between 1st first inspecting point and N-th first inspecting point. When the first flatness index F is larger than a first threshold, the substrate is determined to be unqualified.

Abstract: A method of inspecting flatness of substrate is provided and includes providing a substrate. N first inspecting points are selected from the surface of the substrate along a first straight line, where the coordinate of the i-th first inspecting point is (Xi,Yi,Zi). By using a formula “ D = ? i = 1 N - 1 ? ( X i + 1 - X i ) 2 + ( Y i + 1 - Y i ) 2 + ( Z i + 1 - Z i ) 2 ” , a first measurement length D is calculated. By using a formula “F=(D?S)/S”, a first flatness index F is calculated. S is the horizontal distance between 1st first inspecting point and N-th first inspecting point. When the first flatness index F is larger than a first threshold, the substrate is determined to be unqualified.

Abstract: A method of inspecting flatness of substrate is provided and includes providing a substrate. N first inspecting points are selected from the surface of the substrate along a first straight line, where the coordinate of the i-th first inspecting point is (Xi,Yi,Zi). By using a formula “D=?i=1N?1?{square root over ((Xi+1?Xi)2+(Yi+1?Yi)2+(Zi+1?Zi)2)}”, a first measurement length D is calculated. By using a formula “F=(D?S)/S”, a first flatness index F is calculated. S is the horizontal distance between 1st first inspecting point and N-th first inspecting point. When the first flatness index F is larger than a first threshold, the substrate is determined to be unqualified.

Abstract: A method of inspecting flatness of substrate is provided and includes providing a substrate. N first inspecting points are selected from the surface of the substrate along a first straight line, where the coordinate of the i-th first inspecting point is (Xi,Yi,Zi). By using a formula “D=?i=1N?1?{square root over ((Xi+1?Xi)2+(Yi+1?Yi)2+(Zi+1?Zi)2)}”, a first measurement length D is calculated. By using a formula “F=(D?S)/S”, a first flatness index F is calculated. S is the horizontal distance between 1st first inspecting point and N-th first inspecting point. When the first flatness index F is larger than a first threshold, the substrate is determined to be unqualified.