Method of adjusting wafer processing sequence

A method of adjusting wafer process sequence, comprising steps of:

• collecting a plurality of production parameters for a plurality of lots of wafers;
• selecting a plurality of key parameters from the production parameters,
• wherein the key parameters at least includes a processing sequence;
• defining a formula to obtain an epsilon value, wherein the formula is
• epsilon
• =
• ∑
• i
• =
• 1
• n
• ⁢
• (
• p
• ia
• p
• im
• )
• 2
• ×
• w
• i
• ,
• pia is an acceptable value for one of the key parameters, pim is an upper limit for one of the key parameters, and wi is a weighted value for one of the key parameters;
• defining a minimum point number;
• categorizing the lots of wafers into a plurality of groups according to the epsilon value and the minimum point number by using density-based spatial clustering of application with noise;
• and
• adjusting the processing sequences of the lots of wafers in the groups;
• wherein the density-based spatial clustering of application with noise calculates a difference of the key parameters between two of the lots of wafers by a second formula, the second formula is
• distinct
• =
• ∑
• i
• =
• 1
• n
• ⁢
• (
• p
• i
• -
• p
• i
• ′
• p
• im
• )
• 2
• ×
• w
• i
• ,
• distinct is the difference of the key parameters, pi is one of the key parameters of one lot of wafers, and p′i is one of the key parameters of another lot of wafers.