System for optimizing OPC lithography model parameters

A system for optimizing OPC lithography model parameters, comprises a parameter configuration module, a random direction method module, and a precise search method module;

• wherein
• the parameter configuration module is used to configure an objective function J(u) of a lithography model, as well as a parameter constraint condition and a convergence condition;
• the random direction method module finds preliminary suboptimal parameter combinations in proximity to a plurality of local minima of a lens beam focus BF and defocus start DS of the OPC lithography model by means of a random direction search method;
• and
• the precise search method module obtains, by means of a precise search method, an optimal parameter combination of the lens beam focus BF and defocus start DS of the OPC lithography model on the basis of the suboptimal parameter combinations found by the random direction method module,
• the objective function J(u) of the lithography model is:
• J
• ⁢
• (
• u
• )
• =
• 1
• 2
• ⁢
• n
• ⁢
• ∑
• i
• =
• 1
• n
• ⁢
• wt
• i
• *
• [
• T
• ⁡
• (
• x
• i
• ,
• y
• i
• ,
• BP
• ,
• DS
• )
• -
• CD
• ⁡
• (
• x
• i
• ,
• y
• i
• )
• ]
• 2
• ∑
• I
• =
• 1
• n
• ⁢
• wt
• i
• ,
• u
• =
• [
• BF
• ,
• DS
• ]
• T
• ;
• T(xi, yi, BF, DS) is a CD value estimated by means of an optical imaging model, CD(xi, yi) is a gauge calibration CD value obtained after exposure performed by an actual lithography system, Wti is a weight coefficient, the value of which is in positive correlation with the importance of the CD value, and n is the number of all feature patterns;
• the parameter constraint condition of the objective function J(u) of the OPC lithography model comprises:
• Gj(u)≤0,j∈I;
• G1(u)=a1−BF,G2(u)=BF−b1;
• and
• G3(u)=a2−DS,G4(u)=DS−b2;
• a1 is a BF lower limit value, b1 is a BF upper limit value, a2 is a DS lower limit value, and b2 is a DS upper limit value, i.e., a1≤BF≤b1, and a2≤DS≤b2;
• a1, b1, a2, and b2 are determined by a lithography machine lens projection system and the thickness of a photoresist;
• and
• the convergence condition of the objective function J(u) of the OPC lithography model comprises a random direction error ε1 and a precise search method error ε2, satisfying 0≤ε2<ε1<1.