JP2009283666A - Exposure device and semiconductor manufacturing system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a manufacturing yield. <P>SOLUTION: A semiconductor manufacturing system includes: an operation unit 103 which calculates correction doses for a plurality of coordinates for adjusting the dimensions of a resist pattern formed on a wafer by exposure by a predetermined dose at the plurality of coordinates into predetermined target dimensions, calculates a first approximate function approximating the distribution of the correction dose in the wafer surface, calculates a second approximate function approximating the first approximate function after a trimming processing, the trimming processing being carried out so as to settle the first approximate function between a predetermined upper limit dose and lower limit dose, and outputs recipe parameters including factors of the second approximate function; and an exposure device 105 carrying out exposure processing depending on the recipe parameter. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an exposure apparatus and a semiconductor manufacturing system.

  The manufacturing process of a semiconductor device includes a lithography process for patterning a film to be processed formed on a semiconductor substrate into a desired shape. In the lithography process, the mask pattern of the photomask is transferred to the resist film on the film to be processed, and the film to be processed is processed using the patterned resist film as a mask.

  In a lithography process using a chemically amplified resist film, a heating process called PEB (Post Exposure Bake) for diffusing an acid generated during exposure is generally performed. In the PEB process, since there is a close relationship between the amount of heat supplied and the dimension of the resist film pattern formed after development, strict temperature uniformity within the surface of the substrate to be processed is required.

  In the conventional PEB process, the substrate to be processed is placed on a hot plate heated by a heater to supply heat. However, the substrate to be processed that has undergone the film forming process has a warp due to the stress of the film and the like, and the distance between the hot plate and the substrate to be processed becomes non-uniform in the plane. Therefore, in-plane temperature uniformity of the substrate to be processed is deteriorated, and it is difficult to obtain dimensional uniformity of the resist pattern to be formed.

  In order to solve such problems, a pattern forming method is proposed in which the amount of warpage of a substrate to be processed before exposure is measured, and a correction amount calculated based on the amount of warpage is added to a reference exposure amount to perform exposure processing. (For example, refer to Patent Document 1). This technique utilizes the characteristic that the dimensions (line width and the like) of the resist pattern formed in the lithography process change depending on the dose (exposure amount or exposure time).

However, as the pattern becomes finer, if the pattern is formed with an exposure amount that is simply the calculated correction amount, the positive resist film is removed more than the desired amount due to too much light, resulting in pattern breakage. In addition, since the amount of light is too small, the positive resist film remains without being removed to a desired amount, resulting in a pattern bridge that causes a wiring short circuit, resulting in a reduction in manufacturing yield.
JP 2006-135080 A

  It is an object of the present invention to provide an exposure apparatus and a semiconductor manufacturing system that improve manufacturing yield.

  A semiconductor manufacturing system according to an aspect of the present invention includes a plurality of correction dose amounts for adjusting a dimension at a plurality of coordinates of a resist pattern formed by exposure on a wafer at a predetermined dose amount to a predetermined target dimension. A first approximation function that is calculated for each coordinate and approximates the distribution of the correction dose in the wafer surface is calculated, so that the first approximation function falls within a predetermined range of the upper limit dose and the lower limit dose. Performing a trimming process, calculating a second approximate function that approximates the first approximate function after the trimming process, and outputting a recipe parameter including a coefficient of the second approximate function; An exposure apparatus that performs an exposure process based on the exposure process.

  According to another aspect of the present invention, there is provided a semiconductor manufacturing system including a correction dose amount for adjusting a dimension at a plurality of coordinates of a resist pattern formed by exposure on a wafer at a predetermined dose amount to a predetermined target dimension. Calculate for each of a plurality of coordinates, calculate an approximate function that approximates the distribution of the corrected dose in the wafer surface, and perform trimming processing so that the approximate function falls within a predetermined range of the upper limit dose and the lower limit dose A calculation unit that generates shot map data indicating shot coordinates on the wafer and a dose amount in the shot coordinates based on the approximate function after the trimming process, and outputs a recipe parameter including the shot map data; and the recipe And an exposure apparatus that performs an exposure process based on the parameters.

  An exposure apparatus according to an aspect of the present invention provides an exposure process for a resist film formed on a wafer based on a recipe parameter including a coefficient of an approximate function of a dose distribution expressed using coordinates indicating a position in a wafer surface An exposure apparatus that performs the approximation function based on the coefficient, calculates a dose amount of each shot position in the wafer surface using the approximation function, and the calculated dose amount is a predetermined upper limit dose amount The trimming process is performed so as to be within the range of the lower limit dose amount, and the exposure process is performed based on the dose amount after the trimming process.

  An exposure apparatus according to an aspect of the present invention provides a resist film formed on a wafer based on a recipe parameter including shot map data indicating coordinates indicating a shot position in the wafer surface and a dose amount at the shot position. An exposure apparatus that performs an exposure process, and when the dose amount indicated in the shot map data has a value that exceeds a predetermined upper limit dose amount or a value that is less than a predetermined lower limit dose amount, the upper limit dose amount and the lower limit dose amount The trimming process is performed so as to be within the range, and the exposure process is performed based on the shot map data after the trimming process.

  According to the present invention, the manufacturing yield can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  (First Embodiment) FIG. 1 shows a schematic configuration of a semiconductor manufacturing system according to a first embodiment of the present invention. The semiconductor manufacturing system includes a management unit 101, an apparatus control unit 102, a calculation unit 103, and an exposure apparatus 105. The calculation unit 103 includes a parameter calculation unit 104.

  The management unit 101 performs lot progress management and apparatus status management. The calculation unit 103 is an APC (Advanced Process Control) system that receives notification of lot processing events from the management unit 101 and calculates optimum recipe parameters for each lot.

  The recipe parameters include a mask name, a laser ID, a light source shape, a scan direction, a focus value, and the like used during the exposure process. The position in the wafer plane is designated in the xy coordinate system, and the dose is expressed by a function F (x, y) for each position. The parameter calculation unit 104 calculates parameters (coefficients) of the function F (x, y). Recipe parameters including the parameters of the calculated function F (x, y) are output from the calculation unit 103. The function F (x, y) will be described later.

  Recipe parameters output from the calculation unit 103 are input to the apparatus control unit 102 directly or via the management unit 101. The apparatus control unit 102 converts the received recipe parameter into a unique code of the exposure apparatus 105 and outputs it to the exposure apparatus 105. The exposure apparatus 105 performs an exposure process based on the recipe parameter converted from the code output from the apparatus control unit 102.

  An exposure amount control method by such a semiconductor manufacturing system will be described with reference to a flowchart shown in FIG.

  (Step S201) The management unit 101 issues a recipe parameter calculation request to the calculation unit 103.

  (Step S202) A wafer which has been exposed and developed on the entire surface with the same dose amount Di is prepared, and a resist pattern line width (CD value) at a plurality of coordinates on the wafer is measured. An example of the measured CD value is shown in FIG.

  In FIG. 3, the deviation between the target dimension L1 and the measured CD value caused the wafer to warp due to the stress of the film formed on the wafer, and the heat supply amount became uneven in the PEB process after exposure. This is due to that.

  (Step S203) The computing unit 103 obtains a dose amount at each coordinate on the wafer for adjusting (correcting) the CD value of the resist pattern formed on the wafer to the target dimension L1. When a negative resist film is used, the CD value increases when the dose amount is large, and the CD value decreases when the dose amount is small.

  The dose for correcting the CD value as shown in FIG. 3 to the target dimension is as shown in FIG. At this time, an exposure correction coefficient (sensitivity) indicating the amount of change in the CD value with respect to the amount of change in the dose is required. The exposure correction coefficient is obtained in advance when exposure conditions are set (described later).

Then, the calculation unit 103 calculates a dose amount function f (x, y) that approximates these dose amounts using a least square method. The function f (x, y) is expressed by the following formula (1), for example. In equation (1), j _{1 to} j ₁₅ are real parameters.
f (x, y) = j ₁ + j ₂ x + j ₃ y + j ₄ x ² + j ₅ xy + j ₆ y ² + j ₇ x ³ + j ₈ x ² y + j ₉ xy ² + j ₁₀ y ³ + j ₁₁ x ⁴ + j ₁₂ x ³ y + j ₁₃ x ² y ² + j ₁₄ xy ³ + j ₁₅ y ⁴ (1)
Here, it should be noted that the number of measurement points of the CD value in step S202 is a number that can calculate at least this equation (1).

  (Step S204) The dose amount at each coordinate in the wafer surface is calculated from the function f (x, y) obtained in step S203. Then, the upper limit value D1 and the lower limit value D2 of the dose amount for the target lot device, product type, and process type are searched from the upper and lower limit value tables stored in the storage unit (not shown). An example of the upper and lower limit value table is shown in FIG.

  Then, it is detected whether or not the calculated dose amount in the wafer surface has a value exceeding the upper limit value D1 and a value less than the lower limit value D2. If there is, the process proceeds to step S205, and if not, the process proceeds to step S207.

  The upper limit value D1 and the lower limit value D2 will be described. In the manufacture of semiconductor devices, suitable exposure conditions are detected (exposure conditions are determined) for each device, product, and process before mass production. For example, as shown in FIG. 6, exposure processing is performed on the wafer W while changing the dose amount and the focus value for each shot. In FIG. 6, the dose amount is changed in the vertical direction and the focus value is changed in the horizontal direction. The center value d0 of the dose amount and the center value f0 of the focus value are obtained in advance by simulation.

  After the exposure processing, development processing is performed, and the shape and line width of the resist pattern formed on the wafer W are observed using an SEM or the like. Then, a shot in which a desired resist pattern is formed is detected.

  When the shot in which the desired resist pattern is formed has a distribution as shown in FIG. 7, the dose amount d1 becomes the upper limit value D1, and the dose amount d2 becomes the lower limit value D2. This is because when the dose amount exceeds d1 or the dose amount becomes less than d2, a desired resist pattern is not formed regardless of the focus value. The doses d1 (upper limit value D1) and d2 (lower limit value D2) are stored in a storage unit (not shown) as an upper / lower limit value table as shown in FIG. 5 for each apparatus, product, and process.

  (Step S205) Using the upper limit value D1 and the lower limit value D2 of the dose amount, trimming processing of the dose amount in the wafer surface is performed. That is, the dose amount is set to D1 for a portion where the dose amount exceeds D1, and the dose amount is set to D2 for a portion where the dose amount is less than D2.

  For example, the dose distribution shown in FIG. 4 becomes a distribution shown in FIG. 8 by the trimming process.

(Step S206) The parameter calculation unit 104 calculates a function F (x, y) that approximates the dose distribution after trimming using the least square method. The function F (x, y) is expressed by the following formula (2), for example. In Equation (2), k _{1 to} k ₁₅ are real parameters (coefficients).
F (x, y) = k ₁ + k ₂ x + k ₃ y + k ₄ x ² + k ₅ xy + k ₆ y ² + k ₇ x ³ + k ₈ x ² y + k ₉ xy ² + k ₁₀ y ³ + k ₁₁ x ⁴ + k ₁₂ x ³ y + k ₁₃ x ² y ² + k ₁₄ xy ³ + k ₁₅ y ⁴ (2)

  An example of a function F (x, y) that approximates the dose distribution shown in FIG. 8 is shown in FIG.

(Step S <b> 207) The computing unit 103 outputs recipe parameters including parameters k _{1 to} k ₁₅ of the function F (x, y) to the management unit 101. When the function F (x, y) is not calculated, that is, when the value exceeding the predetermined upper limit value D1 and the value lower than the lower limit value D2 are not detected in step S204 and the trimming process is not performed, the function f ( Recipe parameters including parameters j _{1 to} j ₁₅ of x, y) are output.

  (Step S <b> 208) The management unit 101 outputs a processing start instruction together with recipe parameters to the apparatus control unit 102.

  (Step S209) The apparatus control unit 102 receives the recipe parameter, converts it into a unique code of the exposure apparatus 105, and outputs it to the exposure apparatus 105. The apparatus control unit 102 instructs the exposure apparatus 105 to start processing.

(Step S210) The exposure apparatus 105 performs lot exposure processing based on the received recipe parameters. For example, the dose amount in the shot coordinates (x, y) is calculated using parameters k _{1 to} k ₁₅ included in the recipe parameter, and exposure is performed with the calculated dose amount.

  Further, PEB and development are performed to form a resist pattern.

  As described above, in this embodiment, the dose amount for correcting the dimension value of the resist pattern is trimmed using the upper limit value and the lower limit value that can form a desired resist pattern, and an approximate function is calculated and A parameter is given to the exposure apparatus.

  Thereby, generation | occurrence | production of the pattern cut | disconnection and pattern bridge | bridging by a dose amount being too large or too small is suppressed, and a manufacturing yield can be improved.

  (Second Embodiment) FIG. 10 shows a schematic configuration of a semiconductor manufacturing system according to a second embodiment of the present invention. The semiconductor manufacturing system includes a management unit 1001, an apparatus control unit 1002, a calculation unit 1003, and an exposure apparatus 1005. The calculation unit 1003 has a shot map data creation unit 1004.

  Since the management unit 1001, the apparatus control unit 1002, and the exposure apparatus 1005 are the same as the management unit 101, the apparatus control unit 102, and the exposure apparatus 105 in the first embodiment, description thereof is omitted.

In the first embodiment, the calculation unit 103 (parameter calculation unit 104) calculates a function F (x, y) that approximates the dose distribution after the trimming process, and outputs its parameters k _{1 to} k ₁₅ . However, the calculation unit 1003 in this embodiment does not calculate the approximate function F (x, y) and outputs the dose amount at each shot coordinate.

  The exposure amount control method according to the present embodiment will be described with reference to FIG.

  (Step S1101) The management unit 1001 issues a recipe parameter calculation request to the calculation unit 1003.

  (Step S1102) A wafer which has been exposed and developed with the same dose amount Di on the entire surface is prepared, and the resist pattern line width (CD value) at a plurality of coordinates on the wafer is measured.

  (Step S1103) The computing unit 1003 obtains a dose amount at each coordinate on the wafer for adjusting (correcting) the CD value of the resist pattern formed on the wafer to the target dimension 0.

  Then, the calculation unit 1003 calculates a dose amount function f (x, y) that approximates these dose amounts using the least square method. f (x, y) can be expressed by the same formula as the formula (1) in the first embodiment.

(Step S1104) The dose at each coordinate in the wafer surface is calculated from the function f (x, y) obtained in step S1103. Then, the upper limit value D1 and the lower limit value D2 of the dose amount for the target lot device, product type, and process type are searched from the upper and lower limit value tables stored in the storage unit (not shown).

  Then, it is detected whether or not the calculated dose amount in the wafer surface has a value exceeding the upper limit value D1 and a value less than the lower limit value D2. If there is, the process proceeds to step S1105, and if not, the process proceeds to step S1106.

  (Step S1105) Using the upper limit value D1 and the lower limit value D2 of the dose amount, trimming processing of the dose amount in the wafer surface is performed. That is, the dose amount is set to D1 for a portion where the dose amount exceeds D1, and the dose amount is set to D2 for a portion where the dose amount is less than D2.

  (Step S1106) The shot map data creation unit 1004 creates shot map data that designates shot coordinates and a dose amount at the shot coordinates. FIG. 12A shows an example of shot coordinates, and FIG. 12B shows an example of shot map data.

  (Step S1107) The computing unit 1003 outputs recipe parameters including shot map data to the management unit 1001.

  (Step S1108) The management unit 1001 outputs a processing start instruction together with recipe parameters to the apparatus control unit 1002.

  (Step S1109) The apparatus control unit 1002 receives the recipe parameter, converts it into a unique code of the exposure apparatus 1005, and outputs it to the exposure apparatus 1005. Further, the apparatus control unit 1002 outputs a processing start instruction to the exposure apparatus 1005.

  (Step S1110) The exposure apparatus 1005 performs lot exposure processing based on the received recipe parameters. For example, a dose amount at shot coordinates (x, y) is extracted from shot map data included in the recipe parameter, and exposure is performed with the extracted dose amount. Further, PEB and development are performed to form a resist pattern.

  As described above, in this embodiment, the dose amount for correcting the dimension value of the resist pattern is trimmed using the upper limit value and the lower limit value that can form the desired resist pattern, and is within the range of the upper and lower limit values. Fit.

  Thereby, generation | occurrence | production of the pattern cut | disconnection and pattern bridge | bridging by a dose amount being too large or too small is suppressed, and a manufacturing yield can be improved.

  Each of the above-described embodiments is an example and should be considered as not limiting. For example, although the arithmetic units 103 and 1003 perform the dose trimming process in the above-described embodiment, the exposure apparatuses 105 and 1005 may perform the trimming process. In this case, the exposure apparatuses 105 and 1005 can refer to the upper and lower limit value tables stored in the storage unit (not shown).

For example, the exposure apparatus 105 creates a function f (x, y) using the coefficients j _{1 to} j ₁₅ included in the recipe parameters. Then, the trimming process is performed so that the dose amount in the wafer surface falls within the range between the upper limit value D1 and the lower limit value D2, and the approximate function F (x, y) after the trimming process is calculated. Then, exposure processing is performed with a dose amount based on this function F (x, y). The approximate function F (x, y) may not be obtained, and the exposure process may be performed based on the dose after trimming.

  In the first embodiment, the function F (x, y) approximating the dose distribution after trimming takes a value slightly exceeding the upper limit value D1 and a value slightly lower than the lower limit value D2, as shown in FIG. sell. Therefore, when setting the exposure conditions (FIGS. 6 and 7), the upper and lower limits are set so that the upper limit value D1 is slightly smaller than the dose amount d1 and the lower limit value D2 is slightly larger than the dose amount d2. A value table may be created.

  A similar exposure dose control method (FIGS. 2 and 11) is applied to a wafer that has been exposed with the dose after trimming using the upper limit value D1 and the lower limit value D2, and the dose amount is corrected. You may make it perform.

  The technical scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 is a schematic configuration diagram of a semiconductor manufacturing system according to a first embodiment of the present invention. It is a flowchart which shows the exposure amount control method by the said 1st Embodiment. It is a graph which shows distribution of CD value in a wafer surface. It is a graph which shows distribution of the dose amount for CD value correction | amendment, and its approximate function. It is a figure which shows an example of an upper / lower limit table. It is a figure which shows the dose amount at the time of exposure condition determination, and distribution of a focus value. It is a figure which shows distribution of the shot in which the desired resist pattern was formed. It is a graph which shows dose amount distribution after a trimming process. It is a graph which shows the approximation function of the dose amount distribution after a trimming process. It is a schematic block diagram of the semiconductor manufacturing system by the 2nd Embodiment of this invention. It is a flowchart which shows the exposure amount control method by the 2nd Embodiment. It is a figure which shows an example of shot map data. It is a graph which shows an example of the approximate function of the dose distribution after the trimming process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Management part 102 Apparatus control part 103 Operation part 104 Parameter calculation part 105 Exposure apparatus

Claims (5)

A corrected dose amount for adjusting a dimension at a plurality of coordinates of a resist pattern formed by exposure on a wafer with a predetermined dose amount to a predetermined target dimension is calculated for each of the plurality of coordinates, and the correction dose amount A first approximation function approximating the distribution in the wafer surface is calculated, trimming processing is performed so that the first approximation function falls within a predetermined upper limit dose amount and lower limit dose amount range, and the first approximation function after trimming processing is performed. A calculation unit that calculates a second approximation function that approximates one approximation function and outputs a recipe parameter that includes a coefficient of the second approximation function;
An exposure apparatus that performs an exposure process based on the recipe parameters;
A semiconductor manufacturing system comprising: A corrected dose amount for adjusting a dimension at a plurality of coordinates of a resist pattern formed by exposure on a wafer with a predetermined dose amount to a predetermined target dimension is calculated for each of the plurality of coordinates, and the correction dose amount An approximate function approximating the distribution in the wafer surface is calculated, trimming processing is performed so that the approximate function falls within a range of a predetermined upper limit dose and lower limit dose, and the wafer is processed based on the approximate function after trimming. Creating shot map data indicating the shot coordinates and the dose amount in the shot coordinates, and outputting a recipe parameter including the shot map data;
An exposure apparatus that performs an exposure process based on the recipe parameters;
A semiconductor manufacturing system comprising: A management unit that performs lot progress management, issues a calculation request for the recipe parameter to the calculation unit, receives the recipe parameter output from the calculation unit, and outputs it together with an exposure processing start instruction;
An apparatus control unit that receives the recipe parameter and the exposure process start instruction output from the management unit, outputs the recipe parameter to the exposure apparatus, and controls to start an exposure process;
The semiconductor manufacturing system according to claim 1, further comprising: An exposure apparatus that performs exposure processing of a resist film formed on a wafer based on a recipe parameter that includes a coefficient of an approximate function of a dose distribution expressed using coordinates indicating a position in a wafer surface,
The approximate function is created based on the coefficient, the dose amount at each shot position in the wafer surface is calculated using the approximate function, and the calculated dose amount falls within a range between a predetermined upper limit dose amount and a lower limit dose amount. An exposure apparatus that performs the trimming process as described above and performs the exposure process based on the dose after the trimming process. An exposure apparatus that performs exposure processing of a resist film formed on a wafer based on a recipe parameter including shot map data indicating coordinates indicating a shot position in a wafer surface and a dose amount at the shot position,
When the dose amount indicated in the shot map data includes a value exceeding a predetermined upper limit dose amount or a value less than a predetermined lower limit dose amount, trimming processing is performed so that the dose amount is within the range between the upper limit dose amount and the lower limit dose amount. An exposure apparatus that performs an exposure process based on the shot map data after the trimming process.

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