DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Claim Rejections - 35 USC § 103
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claim(s) 1-13 is/are rejected under 35 U.S.C. 103 as being unpatentable over Chen et al. [US 20060208205 A1, hereafter Chen] in view of Ye et al. [US 20070050749 A1, hereafter Ye].
As per Claim 1, Chen teaches a method for determining an imaging transfer function (modified dose function) of a charged-particle exposure apparatus during exposure of a target positioned in a target plane of said apparatus (See fig. 11), said imaging transfer function describing the distribution of dose or energy generated at the target plane resulting from a single active element in a pattern definition device of the charged-particle exposure apparatus when said single active element is imaged to a substrate in the charged-particle exposure apparatus (Para 17, wherein a dose function indicating the amount of energy in a resist is obtained based on optical tool to be used to form the resist on a wafer),
the method comprising the steps of
i. providing a model of the imaging transfer function, said model including at least one function parameter to be determined (Para 56-58, aerial image model),
ii. selecting a set of imaging properties, including at least one of a beam blur and a beam focus, which are adjustable through modifying pre-defined imaging parameters of the charged-particle apparatus, other than a base exposure dose describing an overall intensity of the imaging transfer function (Para 57);
iii. exposing, using the exposure apparatus, a substrate with a test pattern and developing the substrate to produce a test structure on said at least one substrate (Para 68),
wherein the test pattern comprises a plurality of sub-patterns each of which is a copy of a sub-pattern template modified according to at least one control parameter, said at least one control parameter varying across the sub-patterns of the plurality of sub-patterns within a defined parameter range (Para 37, wherein the diffusion lengths and weights are adjusted and a new modified dose function is calculated), and
wherein the test pattern is exposed to the test substrate a number of times with the base exposure dose and at least one imaging parameter of the charged-particle apparatus being varied, to produce a number of test pattern copies on the substrate, the test structure thus produced comprising a plurality of sub-structures, each sub-structure being associated with specific values of imaging parameters, the base exposure dose, and said at least one control parameter (Para 19-21);
iv. evaluating the sub-structures with respect to at least one measurable quantity, including a critical dimension of features in the sub-structure (Para 18);
v. determining, for each value of the at least one control parameter, the variation of said at least one measurable quantity between the sub-structures as a function of the imaging parameters, and determining, from said variation, a respective value of isofocal dose where the variation is minimally variant with respect to the changes in the imaging parameters (Para 18, The diffusion lengths of the kernels may be adjusted based on the comparison result, if necessary, such that the simulated CD value obtained based on the modified dose function),
vi. calculating, using the values of isofocal dose determined in step v as function of the at least one control parameter the at least one function parameter of the imaging transfer function (Para 37, wherein the diffusion lengths and weights are adjusted and a new modified dose function is calculated).
Chen does not explicitly teach use of a test substrate to produce a test structure on said at least one test substrate.
Ye teaches in today's wafer fabs, exposure tool related optical conditions such as focus, exposure, illumination and aberration may be monitored using test masks and test wafers using specially designed test patterns, or by an exposure tool's self-metrology while undergoing maintenance checks (Para 27).
Therefore, it would have been obvious to one of ordinary skill in the art at time the invention was made to incorporate the test substrate in order to monitor the accuracy of exposure apparatus and perform a desired maintenance before actual production of the device.
As per Claim 2, Chen in view of Ye teaches the method of claim 1.
Chen further disclosed wherein the measurable quantity in steps iv and v includes a critical dimension of a feature of interest in the sub-structures (Para 17-18).
As per Claim 3, Chen in view of Ye teaches the method of claim 1.
Chen further disclosed wherein the imaging transfer function is modeled as weighted sum of radially symmetric Multi-Gaussian functions, said sum including at least three Gaussian components as summands, and in step vi the weights and/or length scales of at least one of said summands are determined (Para 19).
As per Claim 4, Chen in view of Ye teaches the method of claim 3.
Chen further disclosed wherein the imaging transfer function includes a Multi-Gaussian function comprising at least one mid-range component having a weight and a length scale as parameters that are determined in step vi, wherein the length scale corresponds to a width constrained to a range between 200 nm and 2 μm (Para 37 and 56-58, if the simulated resist pattern is not within a predetermined tolerance, the process proceeds to step 20 so as to adjust diffusion lengths, weights, or other resist development paramenters of the Gaussian kernels).
As per Claim 5, Chen in view of Ye teaches the method of claim 1.
Chen further disclosed wherein the method further includes a step of ii′. calculating, in terms of the model provided in step i and the at least one function parameter thereof, a model calculation of said at least one measurable quantity as a function of said subset of the imaging and control parameters and determining the values of the parameters of said subset where said model calculation predicts said at least one measurable quantity to be stationary with respect to said parameters, which step ii′ is performed before step vi, and step vi includes performing a least-squares fit of said model calculation to a course of minimal variation to obtain final parameters of the imaging transfer function (Para 39-40, wherein empirical models may be utilized in the simulation process performed).
As per Claim 6, Chen in view of Ye teaches the method of claim 5.
Chen further disclosed wherein the fitting in step v is performed by finding an optimal value of an evaluation function including a weighted sum of squares of differences between the values of parameters in the model calculation and the course of minimal variation (Para 47).
As per Claim 7, Chen in view of Ye teaches the method of claim 6.
Chen further disclosed wherein the evaluation function is augmented with a regularization term, said regularization term including the first and/or second radial derivatives of the imaging transfer function and/or the magnitude (L2) or sum of absolute values of a vector of imaging transfer functions (L1) (Para 74).
As per Claim 8, Chen in view of Ye teaches the method of claim 1.
Chen further disclosed wherein different values of beam blur are generated by physically defocusing the beam by means of modulation of appropriate electrostatic voltages of lens and/or multi-pole lens components of an imaging system of the charged-particle exposure apparatus (Para 15).
As per Claim 9, Chen in view of Ye teaches the method of claim 1.
Chen further disclosed wherein different values of beam blur are generated by modulating the pattern to emulate an increased blur (Para 12).
As per Claim 10, Chen in view of Ye teaches the method of claim 1.
Chen further disclosed wherein the sub-pattern template is selected from one of the following: a single line, wherein the control parameter is the width of line; a triple line structure comprising a center line surrounded by two outer lines, wherein the control parameter is the width of the two outer lines; a triple line structure comprising a center line surrounded by two outer lines, wherein the control parameter is the distance of the two outer lines from the center line; or a combination of thereof, and the measurable quantity in the resulting sub-structure is the width of the single line or center line, respectively (Para 6, wherein critical dimension of a circuit can be defined as the smallest width of a line or hole or the smallest space between two lines or two holes).
As per Claim 11, Chen in view of Ye teaches an exposed substrate comprising a test structure on at least one test substrate exposed in a charged-particle exposure apparatus according to steps i to iii of the method of claim 1.
Chen further disclosed the test structure comprising a plurality of sub-structures, said sub-structures being formed using copies of the same underlying sub-pattern template modified according to a control parameter varying across the sub-patterns (Para 6, wherein a critical dimension of a circuit can be defined as the smallest width of a line or hole or the smallest space between two lines or two holes. Thus, the CD determines the overall size and density of the designed circuit).
As per Claim 12, Chen in view of Ye teaches the substrate of claim 11.
Chen further disclosed further comprising multiple sub-structures which have been formed in said charged-particle exposure apparatus by applying respective values of imaging parameters, said values being different between each of said multiple sub-structures (Para 48, there are six diffusion lengths).
As per Claim 13, Chen in view of Ye teaches the substrate of claim 11.
Chen further disclosed wherein the underlying sub-pattern template comprises one of the following: a single line, wherein the control parameter is the width of line; a triple line structure comprising a center line surrounded by two outer lines, wherein the control parameter is the width of the two outer lines; a triple line structure comprising a center line surrounded by two outer lines, wherein the control parameter is the distance of the two outer lines from the center line; or a combination of thereof, and the measurable quantity in the resulting sub-structure is the width of the single line or center line, respectively (Para 48).
Conclusion
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/MESFIN T ASFAW/Primary Examiner, Art Unit 2882