Method of adjusting wafer processing sequence

1. 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

,

 p ia is an acceptable value for one of the key parameters, p im is an upper limit for one of the key parameters, and w i 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

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∑

i

=

1

n

⁢

(

p

i

-

p

i

′

p

im

)

2

×

w

i

,

distinct is the difference of the key parameters, p i 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.

2. The method of claim 1 , wherein the production parameters further includes a time gap and a time delay.

3. The method of claim 1 , wherein the step of categorizing the lots of wafers into groups according to the epsilon value and the minimum point number by using density-based spatial clustering of application with noise further comprises steps of:

randomly selecting one of the lots of wafers as a starting point;

calculating the difference of the key parameters between the lot of wafer referred as the starting point and the others of the lots of wafers;

calculating the number of the lots of wafers which have the differences smaller than the epsilon value;

determining whether or not the calculated number is larger than the minimum point number; and

if yes, categorizing the lots of wafers which have the differences smaller than the epsilon value and the lot of wafer referred as the starting point into the same group.

4. The method of claim 3 , further comprising step of:

If no, selecting another lot of wafers as a next starting point.

5. The method of claim 1 , wherein at the step of adjusting the processing sequences of the lots of wafers in the groups, the processing sequences are adjusted to be substantially equal, whereby the lots of wafers in the group can be processed continuously or simultaneously.

6. The method of claim 1 , wherein at the step of adjusting the processing sequences of the lots of wafers in the groups, the processing sequences are adjusted to be almost equal.

7. The method of claim 1 , which is applicable to a production process.

8. The method of claim 7 , wherein the production process includes at least one reference machine and at least one target machine.

9. The method of claim 8 , wherein the target machine is a photolithography machine.

10. The method of claim 8 , wherein the target machine is a batch-type machine.

11. The method of claim 10 , wherein the target machine is a furnace tool.

12. The method of claim 8 , wherein at the step of collecting production parameters for a plurality of lots of wafers, the production parameters are obtained from the at least one reference machine.