JP2003257838A - Method and system for exposure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that, since size and shape of a photoresist in a plurality of patterns in a chip are measured and set values of exposure energy and focus correction values are decided by analyzing measured data in an exposure condition setting work performed for exposure treatment in the course of manufacturing semiconductor devices, types of semiconductor devices are changed quickly and the number of exposure condition setting works increases and, consequently, working efficiency of an exposure system falls and a semiconductor device manufacturing TAT increases when the semiconductor devices are manufactured in a small-scale many-kinds manufacturing mode. <P>SOLUTION: At the time of performing an exposure condition setting experiment for the semiconductor device, the exposure condition for the semiconductor device is set from the size of a photoresist at one point in the chip, measured results, a reticle circuit pattern, specifications of the semiconductor device, and the preacquired information on the size and characteristics of the photoresist so that an error among the plurality of patterns in the chip may become the minimum. Thereafter, the exposure is performed by using the exposure condition. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device manufacturing method, and more particularly to an exposure method and an exposure system for transferring a circuit pattern onto a semiconductor device.

[0002]

2. Description of the Related Art In the manufacture of semiconductor devices, an exposure step of transferring a circuit pattern to a photoresist film on an insulating film formed on a wafer, and a photoresist pattern formed in the exposure step as a mask are used as a mask on the wafer. The circuit pattern is transferred onto a substrate wafer (hereinafter, referred to as a wafer) of a semiconductor device by an etching process for forming a circuit pattern on the insulating film. In the exposure step, first, a photoresist film, which is a photosensitive resin, is formed on the wafer by a coating process, and then, in the exposure process, a circuit pattern is exposed on the photoresist film by using a reduction projection type exposure device. After that, a photoresist pattern is formed by development processing.

In order to satisfy the electrical characteristics of a semiconductor device, the dimensional variation of the pattern transferred on the wafer must be within a certain range. For example, variations in the gate dimensions of the transistors cause variations in the threshold voltage of the transistors, so it is necessary to keep the variations in the dimensions of the photoresist pattern in the gate process within a certain range.

The photoresist pattern has an exposure energy (amount of energy applied to the photoresist film of the photosensitive resin) and a focus correction value by a wafer stage correction drive in a direction perpendicular to the projection lens surface (a focus sensor built in the exposure apparatus is used). The size of the photoresist pattern (hereinafter referred to as the photoresist size) is controlled by using these as control factors, since the position varies with the point recognized as the best focus.

FIG. 1 shows a method of setting exposure energy and focus correction value by a conventional exposure condition setting experiment. First, in the experimental wafer creation step S11, as shown by an arrow, an exposure wafer and an experimental wafer are exposed by changing the exposure energy and the focus correction value for each step shot. Then, in the photoresist pattern dimension measuring step S12, the dimension and shape of the photoresist pattern at each exposure energy and focus correction value are measured by a dimension measuring device (not shown). The dimension measuring device includes a scanning electron microscope (SEM) and an optical measuring device based on analysis of scattered light in a periodic pattern. In addition, usually, the point to be measured is a photoresist pattern corresponding to a pattern that requires the most processing accuracy among the circuit patterns drawn on the reticle. The size of the photoresist pattern at this measurement point is the CD
(Critical Dimension). Next, in the step S13 of creating a focus correction value / exposure energy matrix diagram, the range of the exposure energy and focus correction value is within a certain range from the standard of the CD and the shape measured in the measurement step S12 for each measurement point. Then, a rectangular window called a process window is created, and the center of gravity of the window is set as the exposure energy setting value and the focus correction value setting value for each measurement point. Then, in the step S14 of calculating the setting value of the exposure condition, the setting operation of the exposure condition by the exposure condition setting experiment is performed by the reticle individual difference and the process condition between the exposure processes (for example, the film configuration of the semiconductor device and the illumination optical system of the exposure apparatus). This is performed when the reticle, the exposure process, and the exposure apparatus are changed due to the difference in the illumination conditions (such as the reduction lens numerical aperture NA and the illumination coherency σ) and the machine difference between the exposure apparatuses.

As a method of setting the exposure condition without conducting the exposure condition setting experiment, for example, Goda et al. (Institute of Electronics, Information and Communication, Introducing Response Surface Function for Statistical Design of Optical Lithography Process, 1996) describes exposure energy. And a focus correction value, and a response surface function of the photoresist dimension using the illumination condition of the illumination optical system (reduction lens numerical aperture NA and illumination coherency σ) as variables, and from this response surface function, exposure energy and focus correction We propose a method to calculate the set value.

Also, Christopher.P.Ausschnit et al. (SPI
E, Process window metrology, 2000) creates a cubic equation of photoresist dimension with exposure energy and focus correction value as variables, and automatically adjusts the exposure energy and focus from the photoresist dimension measured in the exposure condition setting experiment. We propose a method to calculate the set value.

[0008]

With the miniaturization of semiconductor device manufacturing, the size required for a photoresist pattern is becoming smaller year by year. In the exposure method using the photolithography technique, as shown in FIG. 2A, the dimension CDreticle / M (magnification) of the circuit pattern on the reticle on the wafer and the corresponding wafer The relationship between the dimension CDwafer of the photoresist pattern becomes non-linear and MEEF (Mask Error Enhancement F
A phenomenon called actors) occurs. Here, MEEF is defined by the following equation (1). As shown in FIG. 2B, the circuit pattern dimension C on the reticle on the wafer is CEF.
When Dreticle / M (magnification) decreases, the value becomes 1 or more. Here, M is the magnification of the reduction projection type exposure apparatus.

[0009]

[Equation 1] In the miniaturized semiconductor device, when the dimensions of the circuit pattern in the chip are different, the dimensional change amount of the photoresist pattern on the wafer is different due to the influence of MEEF described above. Therefore, in the exposure condition setting experiment, it is necessary to create the process window in consideration of not only the CD point in the chip but also other plural circuit patterns having different dimensions. In the exposure condition setting experiment, when the number of measurement points in the chip increases, the measurement time and the time required for the data analysis increase, and as a result, the time required for the exposure condition setting experiment increases.

Particularly, in the system LSI, as shown in FIG. 3, the chip has a plurality of functions such as a memory section and a logic section, and the size of the circuit pattern is different for each functional unit. Therefore, it is necessary to consider a plurality of measurement points in the exposure condition setting experiment, which increases the time required for the exposure condition setting experiment. In addition, since the design of the system LSI is changed for each customer, a large number of products and switching of products is fast.
Therefore, an increase in the number of exposure condition setting experiments performed for each reticle, exposure process, and exposure apparatus further increases the time required for the exposure condition setting experiments. In system LSIs, where quick response to customers leads to expansion of business opportunities, TAT (Turn Around Ti
It is necessary to suppress the increase of (me).

In the method of setting the exposure energy and focus correction value proposed by Goda et al., The photoresist size, the illumination condition of the illumination optical system, the exposure energy,
Since it is expressed by a response curved surface with the focus correction value, it is possible to obtain the exposure energy and the set value of the focus correction value, which are the target photoresist dimensions. However, since the difference in the size of the circuit pattern is not taken into consideration, it is impossible to correct the fluctuation components of the exposure energy and the focus correction value, which depend on the size of the circuit pattern. Further, since the photoresist shape is not taken into consideration in the response curved surface, it is not known whether the setting is appropriate in view of the shape.

In the method of setting the exposure energy and the focus correction value proposed by Christopher et al., The number of pattern dimensions to be managed is one and the photoresist shape is not taken into consideration. I can't solve it.

An object of the present invention is to solve the above problems.
An object of the present invention is to provide an exposure method and a system thereof including an exposure condition setting technique capable of reducing a manufacturing TAT for a semiconductor device such as a system LSI accompanied with miniaturization, and a semiconductor manufacturing method and a system thereof.

[0014]

In order to achieve the above object, the present invention measures the photoresist size and shape of at least one circuit pattern in a chip of a semiconductor device in an exposure condition setting experiment, and measures the photoresist size and shape. From the result, the exposure condition is set in consideration of a plurality of circuit patterns.

That is, according to the present invention, the measurement result of the photoresist dimension and shape in at least one place in the semiconductor device and the circuit pattern information in the semiconductor device (pattern size design value of reticle, manufacturing error, pattern arrangement,
Pattern shape, etc. and semiconductor device specification information (illumination conditions (eg,
Exposure wavelength, reduction lens numerical aperture NA, illumination coherency σ), photoresist conditions (eg type, film thickness, development time), photoresist dimension standard, etc. and photoresist dimension characteristic information (dimension linearity function, MEEF function, etc.) An exposure condition setting step of calculating a setting value of an exposure energy and a focus correction value that minimizes an error from a standard of a plurality of photoresist patterns having different dimensions in a semiconductor device, and the exposure condition setting step. The set value of the exposure energy calculated in the exposure condition setting step, which corrects the focus correction value between the semiconductor device mounted on the stage and the projection optical system according to the set value of the calculated focus correction value Illuminating a predetermined circuit pattern formed on the reticle mounted on the stage from the illumination optical system according to the And an exposure processing step of transferring the predetermined circuit pattern to the semiconductor device by the projection optical system to perform an exposure processing.

Further, according to the present invention, a substrate forming step of forming a semiconductor substrate for setting work by changing exposure energy and a focus correction value to perform an exposure process, and a chip 1 of the semiconductor substrate formed in the substrate forming step A measurement step for measuring the photoresist dimension and shape of a location, and a response for creating a dimension response curved surface and a shape response curved surface with exposure energy and focus correction as variables from the measurement result of the photoresist dimension and shape measured in the measuring step A process window is created from the curved surface creating step, the dimension response surface and shape response surface created in the response surface creating step, and the standard information of the semiconductor device, and the exposure energy and the focus correction value of the exposure energy and the focus correction value are created based on the created process window. An exposure condition setting step including an exposure condition calculation step of calculating a set value, and the exposure condition The focus correction value between the semiconductor device mounted on the stage and the projection optical system is corrected according to the set value of the focus correction value calculated in the exposure condition calculation step of the constant step, The predetermined circuit pattern formed on the reticle mounted on the stage is illuminated from the illumination optical system according to the setting value of the exposure energy calculated in the exposure condition calculation step, and the predetermined circuit pattern illuminated is aforesaid. And an exposure processing step of performing exposure processing by transferring to the semiconductor device by a projection optical system.

Further, according to the present invention, in the exposure condition setting step of the above-mentioned exposure method, further, from the circuit pattern information in the semiconductor device and the photoresist dimension characteristic information, the standard of a plurality of photoresist patterns having different dimensions in the semiconductor device is determined. A semiconductor device variation correction step of correcting the exposure energy calculated in the exposure condition calculation step and the set value of the focus correction value so as to minimize the error of
It is characterized in that the exposure energy corrected and the set value of the focus correction value are obtained from the variation correction process in the semiconductor device.

Also, in the present invention, in the exposure condition calculation step in the exposure condition setting step of the exposure method, measurement data are interpolated from the dimension response curved surface and shape response curved surface of the photoresist and the standard information of the semiconductor device. It is characterized by creating a process window.

Further, according to the present invention, in the step of correcting variation in a semiconductor device in the exposure condition setting step of the exposure method, the circuit pattern size on the reticle and the photoresist size formed on the semiconductor device according to the specifications of the semiconductor device. Using the photoresist dimension characteristic information represented by the relationship with, the relationship between the exposure energy and the photoresist dimension in a plurality of circuit patterns having different dimensions in the semiconductor device and the estimation processing of the photoresist dimension of the corresponding circuit pattern are performed. It is characterized by

Further, according to the present invention, a first database for storing the specification information of the semiconductor device, a second database for storing the results of the exposure condition setting work, and a reticle used for each exposure process for manufacturing the semiconductor device. Consists of a third database that stores circuit pattern information, a fourth database that stores photoresist dimension characteristic information, and a fifth database that stores measurement results of photoresist patterns in exposure condition setting work. And a data calculation station including an exposure condition setting processing unit that performs exposure energy and focus correction value setting processing using each database in the database unit, and an exposure condition setting processing unit of the data calculation station. Depending on the focus correction value that has been set, Correcting means for correcting a focus correction value between the semiconductor device mounted on the projection optical system and a stage according to the setting value of the exposure energy set by the exposure condition setting processing section of the data calculation station. An illumination optical system for illuminating a predetermined circuit pattern formed on a reticle mounted on the reticle, and a predetermined circuit pattern illuminated by the illumination optical system, the semiconductor having the focus correction value corrected by the correction means. An exposure system comprising: the projection optical system which transfers the light to a device and performs an exposure process.

Further, according to the present invention, based on the measurement result of the photoresist size and shape in at least one place in the semiconductor device, the circuit pattern information in the semiconductor device, the semiconductor device specification information and the photoresist size characteristic information, the semiconductor is formed. An exposure condition setting unit that calculates and sets exposure energy and focus correction value setting values that minimize errors from the standards of a plurality of photoresist patterns with different dimensions in the device, and setting processing by the exposure condition setting unit Correction means for correcting the focus correction value between the semiconductor device mounted on the stage and the projection optical system according to the set value of the focus correction value set, and the exposure energy set by the exposure condition setting section. Illuminates a predetermined circuit pattern formed on the reticle placed on the stage according to the set value of Exposure that includes an optical system and the projection optical system that transfers a predetermined circuit pattern illuminated by the illumination optical system onto the semiconductor device whose focus correction value has been corrected by the correction means to perform exposure processing And an exposure apparatus.

The present invention also relates to a size / shape measuring device for measuring the size and shape of a photoresist at one location in a chip of a semiconductor substrate created by performing exposure processing by changing exposure energy and focus correction value. A dimension response curved surface and a shape response curved surface having exposure energy and focus correction as variables are created from the photoresist dimension and shape measurement results measured by the dimension / shape measuring device, and the created dimension response curved surface and shape response curved surface Also, an exposure condition setting unit that creates a process window from the standard information of the semiconductor device, calculates the setting values of the exposure energy and the focus correction value based on the created process window, and performs setting processing, and the exposure condition setting unit. According to the set value of the focus correction value that has been set, the semiconductor device mounted on the stage and the projection Correcting means for correcting a focus correction value with respect to the optical system, and a predetermined circuit pattern formed on the reticle mounted on the stage according to the setting value of the exposure energy set by the exposure condition setting section. An illumination optical system for illuminating the semiconductor device, and a projection optical system for transferring a predetermined circuit pattern illuminated by the illumination optical system onto the semiconductor device whose focus correction value has been corrected by the correction means to perform exposure processing. An exposure system comprising:

According to the configuration described above, the time for the exposure condition setting experiment conducted for each reticle, exposure process, and exposure apparatus is shortened, the operation rate of the exposure apparatus is improved, and the T
AT is reduced. Since the exposure condition is set so that the error of a plurality of patterns in the chip is minimized, the variation of the photoresist dimension in the chip is reduced and the yield of semiconductor devices is improved.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an exposure method, an exposure system, a semiconductor manufacturing method and a manufacturing system according to the present invention will be described with reference to the drawings.

That is, as shown in FIG. 3, manufacturing TA for semiconductor devices such as system LSIs accompanied by miniaturization
Embodiments of an exposure method including an exposure condition setting method capable of reducing T, a system thereof, a semiconductor manufacturing method, and a system thereof will be described.

FIG. 4 shows a first exposure system according to the present invention.
FIG. 3 is an overall configuration block diagram showing the embodiment of FIG. In the figure, an exposure apparatus group 1 is composed of at least one exposure apparatus (1 ... Y) 2. The exposure device 2
Is, for example, a device having a projection optical system for transferring the pattern shown in FIG. In the reduction projection type exposure apparatus 2, the circuit pattern drawn on the reticle 16 on the reticle stage 15 is irradiated with the illumination light having the desired exposure energy from the illumination optical system 17 via the projection optical system (reduction lens) 14 to the wafer. The wafer 13 on the stage 11 is subjected to reduction exposure by one or several chips. Reference numeral 12 indicates focus correction drive in the height direction of the stage on which the wafer is mounted with respect to the projection optical system 14. The range of one-time exposure is called a “shot”. Further, by exchanging the reticle, a circuit pattern necessary for manufacturing a semiconductor device is formed on the wafer. The exposure apparatus group 1 is connected to a data calculation station 7 including an exposure condition setting processing section 8, an input / output interface 9 and a database section 10. Further, the exposure apparatus group 1 is connected to a manufacturing management system 11 that manages the entire semiconductor device manufacturing line. It should be noted that the type, process, and wafer name of the semiconductor device of the wafer at the time of performing the exposure process are input by, for example, reading the product number formed on the wafer, and transmitted from the manufacturing management system 11 via the network. Is possible.

The dimension measuring device group 3 is composed of at least one or more dimension measuring devices (1 ... Z) 4 and is connected to the data calculation station 7 and the manufacturing control system 11. The dimension measuring device 4 includes a scanning electron microscope (SEM) and an optical measuring device based on analysis of scattered light in a periodic pattern.

The reticle group 5 is composed of at least two or more reticles (1 ... X) 6, and the exposure apparatus group 1
It is also connected to the manufacturing control system 11. The type of semiconductor device and the reticle used in the exposure process can be input by, for example, reading the product number formed on the reticle 6, and can be acquired from the manufacturing management system 11 via the network. In addition, there may be a plurality of reticles in the same semiconductor device type and exposure process.

The database unit 10 includes a semiconductor device specification database 101 and an exposure condition result database 1.
02, the reticle circuit pattern database 103,
A dimension characteristic database 104 and an exposure condition determination result database 105 are provided. The semiconductor device specification database 101 includes semiconductor device types /
The exposure process, the photoresist dimension standard in each exposure process, the illumination condition (NA, σ) and the photoresist condition (for example, type, film thickness, development time) are accumulated. The exposure condition result database 102 includes semiconductor device types.
(Product type) / exposure step / exposure device, reticle number, exposure energy for each reticle number, and set value of focus correction value are stored. The reticle circuit pattern database 103 stores reticle circuit pattern information such as reticle numbers that need to be managed by the reticle, circuit pattern dimension design values, manufacturing errors thereof, and pattern layout and pattern shape. The dimension characteristic database 104 includes illumination condition / exposure device / pattern arrangement and shape, photoresist dimension linearity function for each photoresist type (dimension of the circuit pattern on the reticle on the wafer: CDreticle /
The M (magnification) and the corresponding function between the dimension CDwafer of the photoresist pattern on the wafer) and the MEEF function (defined by the above formula (1)) for each NA and σ are registered. The exposure condition determination result database 105 includes, as experimental data, semiconductor device type (product type) / exposure process / exposure apparatus, reticle number, exposure energy in an exposure condition determination experiment performed for each reticle number, focus correction value, and The dimension and shape measurement values of the photoresist for each focus correction value are stored.

Then, in response to the inquiry from the exposure condition setting processing unit 8, the corresponding data is retrieved through the input / output interface 9 and the answer data is transmitted to the exposure condition setting processing unit 8.

The exposure condition setting processing unit 8 calculates the setting values of the exposure energy and the focus correction value based on the data acquired from the database unit 10, and inputs / outputs the calculation result to / from the exposure condition result database 102 of the database unit 10. Register via interface 8.

The manufacturing control system 10 determines the data based on the operation status of each exposure apparatus 2 in the exposure apparatus group 1 and the reticle 9 in the reticle group 8 for performing the exposure processing of the semiconductor device and the in-process information of the wafer, and the data. Upon receiving an instruction from the arithmetic station 7, the semiconductor device and the reticle are conveyed to the corresponding exposure apparatus, and the exposure processing is performed.

FIG. 5 shows a second exposure system according to the present invention.
It is a block diagram showing an embodiment of. The second embodiment differs from the first embodiment in that a data operation station 7 including a database unit 10 and an exposure condition setting processing unit 8 is incorporated in the manufacturing control system 11. Is.

FIG. 6 shows a third exposure system according to the present invention.
It is a block diagram showing an embodiment of. The third embodiment differs from the first and second embodiments in that a data calculation station 7 including a database unit 10 and an exposure condition setting processing unit 8 is provided in each exposure apparatus 2. It is the point that was incorporated.

FIG. 7 shows a fourth exposure system according to the present invention.
It is a block diagram showing an embodiment of. The difference between the fourth embodiment and the first to third embodiments is that the database unit 10 and the exposure condition setting processing unit 8 are different.
This is the point that the data calculation station 7 composed of is incorporated in each dimension measuring device 4.

Although the first to fourth embodiments show the case where the present invention is applied to the exposure processing in the manufacture of semiconductor devices, the present invention is not particularly limited to the manufacture of semiconductor devices, and the projection type The present invention can be similarly applied to the exposure processing of a product using the exposure apparatus of 1.

Next, an exposure processing method for a semiconductor device using the exposure condition setting method executed in the data operation station according to the present invention will be described with reference to FIG.
First, the database unit 10 of the data operation station 7
In step S21, the type, reticle number, exposure process, and exposure apparatus of the semiconductor device that is the target of the exposure process are acquired from the manufacturing management system 11 that manages the semiconductor manufacturing line in advance. The exposure condition setting processing unit 8
In step S22, the reticle number of the device, the exposure process, and the past exposure conditions in the exposure apparatus (including the exposure energy and the focus correction value).
It is searched from the database 102 that stores the results of the exposure conditions whether or not there is the result. If there is a record, the process proceeds to step S33. If there is no actual record, in step S23, an exposure condition setting experiment is instructed for the reticle of the relevant device, the exposure process, and the exposure apparatus. In step S24, a wafer for exposure condition setting experiment is created. The manufacturing condition management system 11 is instructed to perform an exposure condition setting experiment in the exposure condition setting processing unit 8. Then, in the manufacturing control system 11, first, the corresponding device and reticle are conveyed to the exposure apparatus 2. Next, the experimental wafer creation step S11 shown in FIG.
Similarly, the exposure energy and the focus correction value are changed, and the exposure is repeatedly performed to create an exposure condition setting experimental wafer. Alternatively, instead of the manufacturing control system 11, a dedicated terminal may be used to directly instruct the operator to carry the relevant device and reticle to the exposure apparatus 2 and create a wafer for exposure condition setting experiment. The exposure condition setting processing unit 8
In step S25, the dimension measuring apparatus 4 is instructed about the measurement point in the chip of the exposure condition setting experimental wafer. At this time, based on the reticle number on which the exposure process was performed, the measurement point of the reticle and the pattern size and shape (for example, dots, lines, etc.) and arrangement (pattern interval) and the manufacturing error of the pattern at the point The reticle circuit pattern database 103 that stores information about the reticle circuit pattern is searched. When there are a plurality of measurement points at the corresponding reticle number, the exposure condition setting processing unit 8 selects one measurement point having the smallest pattern size and instructs the size measurement apparatus 4. The point to be measured is the photoresist pattern corresponding to the pattern that requires the most processing accuracy among the circuit patterns drawn on the reticle. The size of the photoresist pattern at this measurement point is the CD
(Critical Dimension). In step S26, the dimensions of the photoresist pattern CDwafer (planar dimension of the photoresist (for example, the dimension of the upper surface)) and shape (side cross-sectional shape indicating the cutting degree of the photoresist) at the measurement point designated in step S55 are determined. The dimension measuring device 4 performs the measurement and stores it in the exposure condition determination result database 105. The photoresist pattern shape measured by the dimension measuring device 4 is quantitatively evaluated by the side angle of the pattern, the reduction amount of the resist film, the edge image when observed from the upper surface by SEM, and the like.

The exposure condition setting processor 8 operates in step S27.
In, the photoresist dimension C when the exposure energy and the focus correction value obtained from the dimension measuring device 4 and stored in the exposure condition determination result database 105 are changed
From the measurement result of Dwafer (planar dimension of photoresist (for example, the dimension of the upper surface)), the response curved surface R of the photoresist dimension with the exposure energy and the focus correction value as variables
Create a C _CD is stored in the memory or storage device. Details will be described later with reference to FIG. Further, in step S28, the exposure condition setting processing unit 8 changes the exposure energy and the focus correction value obtained from the dimension measuring device 4 and stored in the exposure condition setting result database 105 (photoresist shape). From the measurement result of the side surface shape indicating the degree of cutting and the reduction amount of the resist film thickness), a response surface of a photoresist shape having exposure energy and a focus correction value as variables is created and similarly stored in a memory or a storage device. Details will be described later with reference to FIG. 11. The exposure condition setting unit 8 further executes step S2.
In 9, the process window is created from the dimension response curved surface and the shape response curved surface of the photoresist, and the setting values of the exposure energy and the focus correction value are calculated and stored in the exposure condition record database 102. Details will be described later with reference to FIG.

In step S30, the exposure condition setting unit 8 corrects the pattern dimension variation in the chip. Here, the exposure energy is corrected so that the dimension error of the plurality of management patterns in the chip is minimized, and the photoresist dimension of each management pattern is estimated. Details will be described later with reference to FIG.

In step S31, the exposure condition setting unit 8 determines whether the estimated value of the pattern dimension in the chip at the exposure energy corrected in step S30 is within the standard. The exposure condition setting unit 8 corrects the circuit pattern size on the reticle and resets the illumination condition in step S32 if the standard is not satisfied, and then performs the process from step S21 again. On the other hand, when the pattern dimension is within the standard, the exposure condition setting unit 8 performs step S3.
In step 3, the manufacturing management system 11 is instructed to perform exposure processing on the device. In the exposure apparatus 2, based on the manufacturing control of the manufacturing control system 11, the exposure process of the corresponding device is performed in step S34. At this time,
The instruction of the exposure process from the exposure condition setting unit 8 is given to the manufacturing management system 11. And the manufacturing control system 1
In step 1, first, the relevant device and reticle are conveyed to the exposure apparatus 2 where exposure is performed. Then, the exposure apparatus 2
An exposure process is performed using the exposure energy and focus correction value calculated in step S30. Alternatively, the operator may directly instruct using a dedicated terminal instead of the manufacturing control system 11, the operator may carry the relevant device and reticle to the exposure apparatus 2 where exposure is performed, and perform the exposure process.

FIG. 10 is a flow chart showing an example of a method of creating a photoresist dimension response curved surface in step S27 of FIG. First, the exposure condition setting processing unit 8
In step S271, the focus correction value (hereinafter, y) for each exposure energy (hereinafter, x _i ) changed in the exposure condition setting experiment, which is obtained from the exposure condition setting result database 105, and the photoresist dimension (hereinafter,
Based on (CD), an approximate curve of the focus correction value and the photoresist dimension for each exposure energy is obtained. For example, each coefficient of a to c is determined by least square approximation of a quadratic expression represented by CD = ay ² + by + c, and an approximate curve is created.
It is stored in a memory or a storage device. In step S272, the exposure condition setting processing unit 8 proceeds to step S271
Based on the approximate curve for each exposure energy obtained in step 1, create a relational expression between the focus correction value and the photoresist size at the exposure energy that is not set in the exposure condition setting experiment by interpolation processing, and similarly create a memory or storage device. Remember. For example, in the case of linear interpolation, the exposure energy x _i
Where CD = f _i (y), exposure energy x
_If the relational expression at _{i + 1} is CD = f _{i + 1} (y), the focus correction value (y) at the exposure energy x
The relational expression between and the photoresist dimension (CD) is given by the expression (2). Here, it is assumed that x is between x _i and x _{i + 1} designated in the exposure condition setting experiment.

[0042]

[Equation 2] Next, in step S273, the exposure condition setting processing unit 8 combines the interpolation curves created in step 202 to create a response surface of a photoresist dimension having exposure energy and a focus correction value as variables, and a memory or a storage device. Remember.

FIG. 11 is a flow chart showing an example of the method of creating the photoresist shape response curved surface in step S28 of FIG. First, the exposure condition setting processing unit 8
In step S281, the photoresist shape evaluation value (hereinafter referred to as S) at the exposure energy (x _i ) and focus correction value (y _j ) changed in the exposure condition setting experiment, which are obtained from the exposure condition setting result database 105, are obtained. Then, the exposure energy and the shape evaluation value Sx, y at the focus correction value, which are not set in the exposure condition setting experiment, are created by the interpolation process and stored in the memory or the storage device.
For example, in the case of linear interpolation, the shape evaluation value at the exposure energy x _i and the focus correction value y _j is Sx _i , y _j . Then, an area (x, y) surrounded by four points of exposure energies x _i and x _{i + 1} and focus correction values y _j and y _{j + 1}
The shape evaluation value Sx, y of is expressed by equation (3).

[0044]

[Equation 3] Further, in step S282, the exposure condition setting processing unit 8 combines the interpolation planes created in step S281, creates a shape response curved surface with exposure energy and focus correction value as variables, and stores the shape response surface in a memory or a storage device. .

FIG. 12 is a flowchart showing the method of creating the process window and the method of calculating the exposure energy and the set value of the focus correction value in step S29 of FIG. First, in step S291, the exposure condition setting processing unit 8 searches the database 101 in which the specifications of the semiconductor device are registered for the device and the standard in the exposure process. The standards include target values and allowable widths of photoresist dimensions and shapes (side angle and amount of reduction in resist film thickness).

The exposure condition setting processing section 8 carries out step S29.
2, the range of the upper limit standard and the lower limit standard of the photoresist dimension CD searched in step S291 is calculated from the photoresist dimension response curved surface RC _CD created in step S27 of FIG. 9 and stored in the memory or the storage device. Boundary lines 1 and 2 of the exposure energy and the focus which are inside are created and stored in a memory or a storage device. For example, in FIG.
In case of the dimension response curved surface of the photoresist created in 0,
A focus correction value yu that changes the exposure energy minutely and becomes the standard limit (upper limit and lower limit) for each exposure energy.
l and yll are calculated from the above equation (2). Then, the dimensional boundary lines 1 and 2 shown in FIG. 13 are created by curve approximation of the exposure energy and the calculated focus correction value, and are stored in the memory or the storage device.

The exposure condition setting processor 8 operates in step S29.
In 3, the range of shapes response surface RC _S of the stored photoresist memory or storage device to create at step S28 in FIG. 9, the upper standards and lower specification of the photoresist shape S which is searched in step S291 A boundary line between the inner exposure energy and the focus is created and stored in a memory or a storage device. For example, if the shape response surface RC _S photoresist created in FIG. 11, the focus correction value minutely varied, and the exposure energy as a specification limit for each focus correction value is calculated from the equation (3). Then, the shape boundary lines 1 and 2 shown in FIG. 13 are created by the curve approximation of the focus correction value and the calculated exposure energy and stored in the memory or the storage device.

Next, in step S294, the exposure condition setting processing section 8 sets the dimension boundary line 1 using the exposure energy and focus correction value created and stored in step S292 as variables, as shown in FIG. 2 and the shape boundary lines 1 and 2 having the exposure energy and focus correction value created and stored in step S294 as variables, the rectangular process so that the area is maximized. Create a window PW.

Next, in step S295, the exposure condition setting processing section 8 as shown in FIG. 13, the center of gravity G of the process window PW created in step S294 described above.
Is calculated, and the points intersecting with the respective axes of the center of gravity G are stored in a memory, a storage device or the like as the set values of the exposure energy and the focus correction value. In addition, the exposure condition setting processing unit 8
Calculates the photoresist dimension CD at this set value from the above equation (2). Further, the exposure condition setting processing unit 8
In step S296, the distance from the center of gravity G to the end of the process window is calculated for each axis, and stored as the exposure energy and the focus correction value margin.

FIG. 13 shows the result of creating the dimension boundary lines 1 and 2 and the shape boundary lines 1 and 2 processed in step S29 of FIG. 9 and the process window PW created from them.
And the setting values of the exposure energy and the focus correction value.

Next, the exposure condition setting processing section 8 performs the process shown in FIG.
A method of correcting the in-chip dimension variation component in step S30 shown in FIG. 14 will be described with reference to FIG. Figure 14
10 is a flowchart showing a method of correcting a dimension variation component in a chip in step S30 of FIG. First, in step S301, the exposure condition setting processing unit 8 determines a pattern design value, a pattern arrangement (such as a pattern interval), a pattern shape (such as a dot or a line), and a pattern manufacturing error that need to be managed at the relevant reticle number. Is searched from the reticle circuit pattern database 103 used in step S25 of FIG. Here, the management pattern dimension is a value obtained by adding a manufacturing error to the dimension design value on the reticle. Further, hereinafter, the plurality of retrieved management patterns are represented by m. Then, m = 1 is the pattern used for exposure condition setting.

The exposure condition setting processor 8 operates in step S30.
2, the relevant device and illumination conditions in the exposure process (reduction lens numerical aperture NA, illumination coherency σ)
Then, the photoresist condition (resist type) and the photoresist dimension standard for each management pattern are searched from the semiconductor device specification database 101 in which the semiconductor device specifications used in step S29 of FIG. 9 are registered.

The exposure condition setting processor 8 operates in step S30.
3, the pattern arrangement and pattern shape searched in step S301, the illumination condition searched in step S302, and the dimension linearity function and the MEEF function in the corresponding exposure apparatus are registered as the dimension characteristics of the photoresist. Database 104
Search from. The dimension characteristic database 104
The dimensional linearity function and MEEF function are registered in advance for each illumination condition, pattern arrangement and shape, exposure apparatus, and photoresist type. Here, the dimension linearity function means, as shown in FIG. 2A, the pattern dimension (CD
reticle / M (magnification) and the photoresist size (CDwafer) on the wafer. ME
As shown in FIG. 2B, the EF function means the pattern size (CDreticle / CDreticle /
It is a function that represents the relationship between M (magnification) and the MEEF value. Further, the MEEF function can be calculated from the dimension linearity function using the above equation (1). Further, the dimension linearity function can be calculated from an evaluation experiment, illumination conditions, circuit pattern information, and reduction lens aberration information of the exposure apparatus, using an optical simulator.

The exposure condition setting processor 8 operates in step S30.
In 4, the photoresist dimension CD (m) of the control pattern which is not measured in the exposure condition setting experiment is estimated. First, in step S3041, a relationship (photoresist sensitivity coefficient) between the exposure energy and the photoresist dimension at the focus correction value set in step S295 of FIG. 12 is created for each management pattern. Here, the photoresist sensitivity coefficient is a slope a represented by CD = ax + b where x is the exposure energy and CD is the photoresist dimension. A photoresist sensitivity coefficient (a (1)) in the pattern used in the exposure condition setting experiment is created from the dimension response curved surface RC _CD . The photoresist sensitivity coefficient (a (m)) in the other management patterns is the same as the photoresist sensitivity coefficient (a (1)) in the exposure condition setting pattern according to the following equation (4). m)) and MEEF of exposure condition setting pattern
It is calculated by multiplying the ratio of the values (MEEF (1)).

[0055]

[Equation 4] In step S3042, the dimension CDcal (1) of the pattern used for exposure condition determination is obtained from the dimension linearity function retrieved in step S303. In step S3043, the difference ΔCD (1) between the photoresist dimension value CD (1) at the exposure energy set in the exposure condition setting experiment and the dimension CDcal (1) of the pattern used in the exposure condition setting is obtained from the dimension linearity function. In step S3044, the exposure energy change amount Δx corresponding to ΔCD (1) obtained in step S3043.
Is calculated from the photoresist sensitivity coefficient a (1) by the following equation (5).

[0056]

[Equation 5] In step S3045, the photoresist dimension CD (m) of each management pattern is changed to the dimension CDcal (m) obtained from the dimension linearity function according to the following equation (6), and the change amount Δx of the exposure energy and the photoresist sensitivity coefficient a.
Calculate by adding the product of (m).

[0057]

[Equation 6] In step S305, the exposure condition setting processing unit 8
Based on the photoresist dimension CDm of each management pattern calculated in step S3045, the exposure energy correction amount Δxopt that minimizes the evaluation index Q defined by the following equation (7) is calculated.

[0058]

[Equation 7] Here, gain is a weighting function and can change the weight in the evaluation index Q according to the importance of the management pattern. Target is a target value of the photoresist size of the management pattern.

Then, in step S306, the exposure condition setting processor 8 determines the photoresist dimension CD 'of the management pattern when the exposure energy is corrected based on the photoresist dimension CDm of each management pattern calculated in step S3045. m is estimated by the following equation (8).

[0060]

[Equation 8] As described above, the exposure condition setting processing unit 8 causes the step S30
In, it is possible to correct the dimension variation component in the chip by estimating the photoresist dimension CD′m of each management pattern when the exposure energy is corrected so that the dimension error of the plurality of management patterns in the chip is minimized. Become.

Next, in step S33 shown in FIG. 9, when the exposure condition setting unit 8 instructs the manufacturing management system 11 to perform an exposure process for the corresponding device, the semiconductor device, the reticle, the exposure process, and the exposure apparatus are exposed. FIG. 15 shows an example of an output screen of exposure energy and focus correction value.
Will be explained. On this output screen, the name of the semiconductor device type to be exposed, the exposure process, the exposure apparatus, the reticle name, the calculated exposure energy, and the focus correction value are displayed. In addition, this output screen is either the output terminal of the manufacturing control system 11 or a dedicated output terminal,
And to the exposure apparatus 2.

As described above, according to the present invention, the data operation station 7 includes the first database 101 in which the semiconductor device specification information is stored, the plurality of types, the exposure process, the exposure energy and the focus correction value in the exposure apparatus. A second database 102 in which the setting values of
Third database 1 for storing circuit pattern information of a reticle used in each exposure process of semiconductor device manufacturing
03, the fourth database 104 that stores the illumination condition, the pattern arrangement, and the photoresist dimension characteristics in the exposure apparatus, and the measurement result of the photoresist dimension and shape for each exposure energy and focus correction value measured in the exposure condition setting experiment. The database unit 10 including a fifth database 105 for storing the data, the measurement result of the photoresist size and shape at one point in the chip, the multiple pattern size in the chip, and the photoresist size characteristics of the corresponding pattern. Exposure condition setting processing unit 8 that sets the exposure condition so that the dimensional error of the plurality of patterns is minimized.

In the exposure condition setting processing section 8, as shown in FIG. 9, (1) step S23 for instructing the creation of the exposure condition setting experimental wafer, and (2) the measurement point of the photoresist dimension and the measurement instruction. Step S25 to be performed
And (3) Step S27 of creating a dimension response curved surface with the exposure energy and the focus correction value as variables from the measured photoresist dimension, and (4) the exposure energy and focus correction value as the variables from the measured photoresist shape. Step S28 of creating a shape response surface, and (5)
Step S of creating a process window from the dimension and shape response curved surfaces created in (3) and (4) and calculating the setting values of the exposure energy and the focus correction value.
29, and (6) Step S30 of calculating a correction value of the exposure energy so as to minimize the dimensional error in a plurality of patterns in the chip from the photoresist dimensional characteristics acquired in advance. By sequentially performing the step (6), the exposure condition setting process is performed.
The exposure process can be performed using the exposure conditions.

As described above, according to the embodiment of the present invention, in the work of setting the exposure conditions in the semiconductor device manufacturing, the photoresist dimensions and shapes of a plurality of patterns in the chip are measured and the data analysis is performed. The work of calculating the setting values of the exposure energy and the focus correction value was taken into consideration the unmeasured pattern in the chip from the measurement result of one point in the chip, the reticle circuit pattern information, the semiconductor device specification information and the photoresist dimension characteristic information. Since it has a function of calculating the setting value of the exposure energy and the focus correction value, the time required for setting the exposure condition of the exposure processing of the semiconductor device is reduced, the operating rate of the exposure apparatus is improved, and the TAT ( Tu
rn Around Time) can be reduced. FIG.
In the conventional method and the TA of the semiconductor device according to the present invention,
A comparison of T is shown. According to the present embodiment, the dead time is reduced by shortening the time required for the exposure condition setting experiment, and the TAT can be shortened.

Further, according to the present embodiment, since it has a function of estimating the photoresist dimensions of a plurality of patterns in the chip, it is possible to judge whether the pattern dimensions in the chip are within the standard, Occurrence of non-standard can be reduced.

Further, according to the present embodiment, since it has a function of setting the exposure condition so that the error of a plurality of patterns in the chip is minimized, the variation of the photoresist dimension in the chip is reduced, and the semiconductor device is reduced. It is possible to improve the yield of.

[0067]

According to the present invention, it is possible to reduce the time required to set the exposure conditions of the exposure processing of the semiconductor device, improve the operation rate of the exposure apparatus, and reduce the TAT of the semiconductor device. Has the effect.

[Brief description of drawings]

FIG. 1 is a diagram showing a conventional exposure energy and focus correction value setting method.

FIG. 2 is a diagram showing dimensional characteristics of a photoresist.

FIG. 3 is a diagram showing a configuration inside a chip of a system LSI.

FIG. 4 is a block diagram showing a first embodiment according to the present invention.

FIG. 5 is a block diagram showing a second embodiment according to the present invention.

FIG. 6 is a block diagram showing a third embodiment according to the present invention.

FIG. 7 is a block diagram showing a fourth embodiment according to the present invention.

FIG. 8 is a diagram showing a configuration of a projection reduction type exposure apparatus according to the present invention.

FIG. 9 is a flowchart showing a semiconductor device exposure method using the exposure condition setting method according to the present invention.

FIG. 10 is a diagram showing an example of a method of creating a response surface of a photoresist dimension according to the present invention.

FIG. 11 is a diagram showing an example of a method of creating a photoresist-shaped response curved surface according to the present invention.

FIG. 12 is a flowchart showing a method of creating a process window and a method of calculating a setting value of exposure energy and a focus correction value according to the present invention.

FIG. 13 is a diagram showing an example of a result of creating a process window and a result of calculating setting values of exposure energy and a focus correction value according to the present invention.

FIG. 14 is a flowchart showing a method for correcting a pattern dimension variation component in a chip according to the present invention.

FIG. 15 is an example of an output screen of an exposure condition setting result according to the present invention.

FIG. 16 is a diagram for explaining the effect of the present invention.

[Explanation of symbols]

1 ... Exposure device group, 2 ... Exposure devices 1 to Y, 3 ... Dimension measuring device group, 4 ... Dimension measuring devices 1 to Z, 5 ... Reticle group, 6 ...
Reticles 1 to X, 7 ... Data operation station, 8 ... Exposure condition setting processing unit, 9 ... Input / output interface, 10
... Database part, 11 ... Manufacturing management system, 101 ...
Semiconductor device specification database 102 ... Exposure condition actual result database 103 ... Reticle circuit pattern database 104 ... Dimension characteristic database.

Claims (8)

[Claims] 1. A dimension in a semiconductor device based on a measurement result of the photoresist dimension and shape at least at one location in the semiconductor device, circuit pattern information in the semiconductor device, semiconductor device specification information, and photoresist dimension characteristic information. Exposure condition setting step for calculating the setting value of the exposure energy and the focus correction value that minimizes the error from the standard of a plurality of different photoresist patterns, and the focus correction value setting value calculated in the exposure condition setting step. The focus correction value between the semiconductor device mounted on the stage and the projection optical system is corrected accordingly, and the illumination optical system shifts the stage from the illumination optical system according to the setting value of the exposure energy calculated in the exposure condition setting step. Illuminate a predetermined circuit pattern formed on the mounted reticle, and the illuminated predetermined circuit pattern And an exposure processing step of performing exposure processing by transferring the image onto the semiconductor device by the projection optical system. 2. A substrate forming step of forming a semiconductor substrate for setting work by performing exposure processing by changing exposure energy and a focus correction value, and a photoresist at one location in a chip of the semiconductor substrate formed in the substrate forming step. A measurement step of measuring dimensions and shapes, and a response curved surface creation step of creating dimension response curved surfaces and shape response curved surfaces with exposure energy and focus correction as variables from measurement results of photoresist dimensions and shapes measured in the measurement steps , Creating a process window from the dimension response surface and shape response surface created in the response surface creating step and the standard information of the semiconductor device, and calculating the setting values of the exposure energy and the focus correction value based on the created process window Exposure condition setting step including an exposure condition calculation step, and an exposure condition of the exposure condition setting step The exposure condition calculation step of the exposure condition setting step, which corrects the focus correction value between the semiconductor device mounted on the stage and the projection optical system according to the setting value of the focus correction value calculated in the condition calculation step. The illumination optical system illuminates a predetermined circuit pattern formed on the reticle mounted on the stage in accordance with the set value of the exposure energy calculated in step 1, and the illuminated predetermined circuit pattern is projected by the projection optical system. And an exposure processing step of performing exposure processing by transferring the semiconductor device. 3. The exposure condition setting step further minimizes an error from a standard of a plurality of photoresist patterns having different dimensions in the semiconductor device based on circuit pattern information in the semiconductor device and photoresist dimension characteristic information. A semiconductor device variation correction step for correcting the exposure energy calculated in the exposure condition calculation step and the set value of the focus correction value, and the exposure energy and focus correction value corrected from the semiconductor device variation correction step. The exposure method according to claim 2, wherein a set value is obtained. 4. The exposure condition calculation step in the exposure condition setting step creates a process window in which measurement data is interpolated from the dimension response curved surface and shape response curved surface of the photoresist and standard information of the semiconductor device. The exposure method according to claim 2. 5. A photo expressed by a relationship between a circuit pattern dimension on a reticle and a photoresist dimension formed on the semiconductor device in the specification of the semiconductor device in the semiconductor device variation correction process in the exposure condition setting process. 4. The method for estimating the photoresist dimension of a corresponding circuit pattern and the relationship between the exposure energy and the photoresist dimension in a plurality of circuit patterns having different dimensions in a semiconductor device, using the resist dimension characteristic information. The exposure method described. 6. A first database for storing specification information of a semiconductor device, a second database for storing results of exposure condition setting work, and reticle circuit pattern information used in each exposure step of semiconductor device manufacturing. And a database unit including a third database to be stored, a fourth database to store the photoresist dimension characteristic information, and a fifth database to store the measurement result of the photoresist pattern in the exposure condition setting work. , A data calculation station including an exposure condition setting processing unit that performs setting processing of exposure energy and focus correction value using each database in the database unit, and setting processing is performed by the exposure condition setting processing unit of the data calculation station. Placed on the stage according to the focus correction setting A correction unit that corrects a focus correction value between the semiconductor device and the projection optical system, and a mounting unit mounted on the stage according to the setting value of the exposure energy set by the exposure condition setting processing unit of the data calculation station. An illumination optical system for illuminating a predetermined circuit pattern formed on the reticle and a predetermined circuit pattern illuminated by the illumination optical system are transferred to the semiconductor device whose focus correction value is corrected by the correction means. And an exposure apparatus having the projection optical system for performing exposure processing. 7. A dimension in a semiconductor device based on a measurement result of the photoresist dimension and shape in at least one location in the semiconductor device, circuit pattern information in the semiconductor device, semiconductor device specification information, and photoresist dimension characteristic information. Exposure energy setting unit that calculates and sets exposure energy and focus correction value setting values that minimize the error from the standard of a plurality of different photoresist patterns, and focus correction processing set by the exposure condition setting unit Correction means for correcting the focus correction value between the semiconductor device mounted on the stage and the projection optical system according to the set value of the value, and the set value of the exposure energy set by the exposure condition setting section. And an illumination optical system for illuminating a predetermined circuit pattern formed on the reticle mounted on the stage, And an exposure apparatus including the projection optical system that transfers a predetermined circuit pattern illuminated by a bright optical system onto the semiconductor device whose focus correction value has been corrected by the correction unit to perform exposure processing. An exposure system characterized in that 8. A size / shape measuring device for measuring the size and shape of a photoresist at one location in a chip of a semiconductor substrate, which is formed by performing exposure processing by changing exposure energy and focus correction value, and the size / shape. A dimension response curved surface and a shape response curved surface having exposure energy and focus correction as variables are created from the measurement result of the photoresist dimension and shape measured by the measuring device, and the created dimension response curved surface and shape response curved surface and the semiconductor device An exposure condition setting unit that creates a process window from the standard information, calculates the setting values of the exposure energy and the focus correction value based on the created process window, and performs the setting process; and the exposure condition setting unit that performs the setting process. Between the semiconductor device mounted on the stage and the projection optical system according to the focus correction value A correction unit for correcting the focus correction value, and an illumination optical system for illuminating a predetermined circuit pattern formed on the reticle mounted on the stage according to the setting value of the exposure energy set by the exposure condition setting unit. And an exposure apparatus including the projection optical system configured to transfer a predetermined circuit pattern illuminated by the illumination optical system to the semiconductor device whose focus correction value is corrected by the correction unit to perform exposure processing. An exposure system comprising: