KR20120093723A - Method for correction of overlay error in semiconductor device - Google Patents

Method for correction of overlay error in semiconductor device Download PDF

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Publication number
KR20120093723A
KR20120093723A KR1020110013467A KR20110013467A KR20120093723A KR 20120093723 A KR20120093723 A KR 20120093723A KR 1020110013467 A KR1020110013467 A KR 1020110013467A KR 20110013467 A KR20110013467 A KR 20110013467A KR 20120093723 A KR20120093723 A KR 20120093723A
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South Korea
Prior art keywords
reticle
overlay error
overlay
pattern
light source
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KR1020110013467A
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Korean (ko)
Inventor
권기성
홍성목
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에스케이하이닉스 주식회사
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Priority to KR1020110013467A priority Critical patent/KR20120093723A/en
Publication of KR20120093723A publication Critical patent/KR20120093723A/en

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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/70483—Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
    • G03F7/70605—Workpiece metrology
    • G03F7/70616—Monitoring the printed patterns
    • G03F7/70633—Overlay, i.e. relative alignment between patterns printed by separate exposures in different layers, or in the same layer in multiple exposures or stitching
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/027—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34
    • H01L21/0271—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34 comprising organic layers
    • H01L21/0273—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34 comprising organic layers characterised by the treatment of photoresist layers
    • H01L21/0274—Photolithographic processes

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Manufacturing & Machinery (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)

Abstract

An overlay correction method of a semiconductor device of the present invention includes measuring an overlay error of a reticle including a first pattern to be formed on a wafer; Introducing an optical module including a slit for changing a path of a light source irradiated to a portion where an overlay error occurs on the reticle; And arranging the reticle into which the optical module is introduced, in the optical equipment and irradiating the light source to transfer the second pattern having the overlay error corrected to the wafer by the light source passing through the slit in which the path of the light source is changed.

Description

Method for correction of overlay error in semiconductor device

The present invention relates to semiconductor device manufacturing, and more particularly, to an overlay correction method of a semiconductor device.

A lithography process is performed to transfer shapes of different patterns formed on a plurality of reticles onto a wafer in the process of manufacturing a semiconductor device. The patterns of the patterns formed on the plurality of reticles may be sequentially transferred onto the wafer by applying a photoresist film on the wafer and then performing exposure and development to implement a circuit pattern required for the operation of the semiconductor device.

1 is a view schematically showing the optical equipment for pattern formation used in the lithography process.

Referring to FIG. 1, the optical equipment for forming a pattern includes a light source 105, an illumination system 110, a reticle 120, a reduction projection exposure system 130, and a stage 135 on which a wafer 140 is disposed. It is configured by. The pattern 125 formed on the reticle 120 is manufactured to be 2.5 to 5 times the size of the pattern 125a to be formed on the wafer 140, and is reduced by the projection through the reduction projection exposure system 130. The reduced pattern 125a having the same shape as the pattern 125 formed on the reticle 120 is formed on the 140. One of the important points in this lithography process is an overlay in which the shapes of the different patterns constituting the circuit pattern are exactly aligned and overlapped. Overlay is an index indicating an alignment between a layer formed in a previous process and a layer formed in a current process in manufacturing a semiconductor device having a stacked structure. Overlays have become very important in the trend of high integration of semiconductor devices.In a typical semiconductor manufacturing process, overlays between layers are measured to determine and correct the alignment between the layers formed in the previous process and the layers formed through the current process. have. And overlay correction is performed based on the measured overlay information to transfer the desired pattern onto the wafer.

However, due to defects in the reticle, such as defects in the manufacturing of the reticle, defects in the process of adjusting the line width uniformity, or the tilt angle of the stage where the reticle is placed is off the target. When the overlay error of the intrafield is induced, the overlay error is measured at different values at the upper and lower portions of the field, thereby making it difficult to correct the correction. In addition, the overlay error of the intrafield caused by the distortion of the lens of the exposure equipment is also difficult to correct. In the case where an overlay error occurs as described above, if the correction is not performed, the overlay error is transferred onto the wafer, which may lead to wafer defects. Thus, a method of correcting the overlay error is required.

SUMMARY OF THE INVENTION The present invention provides an overlay correction method of a semiconductor device capable of improving an overlay error of a wafer by controlling an intrafield overlay error, which is an overlay error in a field due to a defective reticle or a component of an exposure apparatus. It is.

An overlay correction method of a semiconductor device according to the present invention includes measuring an overlay error of a reticle including a first pattern to be formed on a wafer; Introducing an optical module including a slit on the reticle to change a path of a light source irradiated to a portion where the overlay error occurs; And disposing a reticle into which the optical module is introduced, in optical equipment, and irradiating a light source to transfer a second pattern having an overlay error corrected to a wafer by a light source passing through a slit in which the path of the light source is changed. It features.

In the present invention, the measuring of the overlay error may include measuring an alignment state of the first pattern; Comparing the alignment of the first pattern with the alignment of the reference pattern to be formed on the wafer; And measuring the degree and the position of deviation of the first pattern from the alignment of the reference pattern and defining the residual value as a residual value.

The overlay error of the reticle is preferably measured in rectangular field units.

The overlay error measured in the field unit may include an overlay error in which the upper and lower portions of the field are asymmetric with each other or an overlay error in which the upper and lower portions except the center of the field are symmetrically generated. Do.

The optical module may include a first plate having a first inclined plane that primarily changes the path of the light source in a portion corresponding to the first area where the overlay error of the reticle is measured, and the first in the plane facing the first inclined plane. It is preferable to include a second plate having a second inclined surface that secondary changes the path of the changed light source.

Preferably, the optical module has a flat surface on the reticle where the overlay has a normal value.

Preferably, the optical module is attached to the reticle or attached to a stage of the optical equipment in which the reticle is disposed.

Transferring the second pattern having the overlay error corrected may be corrected by selectively changing a path of a light source in a portion where an overlay error occurs in the reticle.

According to the present invention, a defect occurs in the process of manufacturing the reticle, a defect occurs in the process of adjusting the line width uniformity, or an intra caused by the defect of the lens of the exposure apparatus or the defect of the reticle due to the inclination of the reticle stage. Overlay error in the field can be controlled. Accordingly, the yield error can be improved by improving the overlay error of the wafer.

1 is a view schematically showing the optical equipment for pattern formation used in the lithography process.
2 and 3 illustrate the types of overlay errors generated on a wafer.
4 is a flowchart illustrating a method for correcting an inter-field overlay according to the present invention.
5A through 5C are diagrams for explaining the inter-field overlay correction method according to an embodiment of the present invention.
6 and 7 illustrate a method of correcting an overlay error generated in various forms by applying the optical module of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

2 and 3 illustrate the types of overlay errors generated on a wafer. Referring to FIGS. 2 and 3, the overlay can analyze the error in two forms, for example, when analyzing in a state implemented on a wafer, as shown in FIG. It can be detected as an intrafield overlay error and an interfield overlay error which is an error due to the shape in the field shown in FIG. 3. Referring back to FIG. 2, the overlay error can be measured residually. "Residual" is defined as the remaining value to remove the overlay error that can be corrected by grasping the alignment between the layer formed in the previous process and the layer formed through the current process. To do this, first measure the alignment of the pattern formed on the reticle, compare the alignment of the pattern formed on the reticle with the degree of alignment of the reference pattern to be formed on the wafer, and then remove the pattern formed on the reticle from the alignment of the reference pattern. The accuracy and position are measured and defined as residual values. Here, the residual value may determine the degree and position of deviation from the pattern to be originally formed in the direction and size of the arrow. Specifically, in the field 201 disposed in the center of the wafer 200 of FIG. 2, the field and the field are formed in the correct position so that an overlay error does not occur (203), while the field and the field toward the edge of the wafer 200 are increased. Overlapping differences occur between 205 and 206 so that the residual value is measured to be large. Such residuals are generally being calibrated for linear analysis, but there is an overlay error that is difficult to calibrate with linear analysis. Overlay errors that are difficult to correct by linear analysis are called intrafield overlay residuals. For example, referring to FIG. 3, an overlay error is observed in a trapezoidal form for an intrafield overlay error, which is an error due to a shape in a field. The intrafield overlay error is reduced in the direction of the arrow in the field 215, which is actually formed based on the field 210 to be originally formed (a), and in the direction of the arrow in the direction of the arrow (b). Is occurring. In this case, it is difficult to calibrate because different calibrations must be performed on the upper and lower portions, respectively.

The overlay error in the trapezoidal shape is caused by a tilt angle of the stage on which the reticle is disposed, or is identified as a reticle registration error generated in manufacturing the reticle. In addition, the intrafield overlay error is controlled by the laser irradiation on the quartz substrate of the reticle to adjust the line width (CD) in the field to secure the line width uniformity. It is observed to occur. In the case where an overlay error occurs as described above, if the correction is not performed, the overlay error is transferred onto the wafer, which may lead to wafer defects. Thus, a method of correcting the overlay error is required.

Accordingly, the present invention intends to improve the intrafield overlay by correcting the overlay error generated differently in each field in the field.

4 is a flowchart illustrating a method for correcting an inter-field overlay according to the present invention. 5A through 5C are diagrams for explaining the inter-field overlay correction method according to an embodiment of the present invention.

4 and 5A, a reticle 500 including a pattern 510 to be formed on a wafer is manufactured (S400). Referring to FIG. 5A, a mask pattern 510 to be transferred to a wafer is formed on a transparent substrate 505 including quartz. The mask pattern 510 may be formed as a single layer or a stacked layer structure having a light blocking layer pattern including chromium (Cr) or a phase shifting layer pattern including a phase shifting material.

Next, the overlay error of the reticle is measured (S410). Referring to FIG. 5B, in which a single field 500a is selected from a reticle 500 having a plurality of fields, an overlay error due to a registration failure of a reticle is indicated by a region 'I' in the lower left of the field. As indicated by the arrows at, it was measured that an overlay error extending out of the field occurred.

When an overlay error occurs as described above, an optical module for correcting the generated overlay error is attached to the reticle (S420). Specifically, referring to FIG. 5C, an optical module 535 having a slit 545 capable of shifting a path of a beam irradiated from a light source on a reticle 500 is manufactured and attached. . The optical module 535 has a first inclined surface 541 in a portion corresponding to the 'I' region where the overlay error due to poor registration of the reticle is measured, and a flat surface 542 in the normal region II. The second plate 530 having the second inclined surface 543 on the surface facing the first plate 525 and the first inclined surface 541 and the flat surface 542 in the normal region II. It is configured to include. Here, the first plate 525 and the second plate 530 are bonded to each other by a first distance d using the first support 540. The optical module 535 including the first plate 525 and the second plate 530 is attached to the reticle 500 using an adhesive layer or a second support 520. The first plate 525 and the second plate 530 may be made of a material containing quartz. In this case, the optical module 535 may be directly attached to the reticle or attached to a stage where the reticle is disposed.

Next, the reticle 500 to which the optical module 535 is attached is placed on the pattern forming optical equipment (see FIG. 1), and the light source is irradiated to transfer the pattern having the overlay error corrected to the wafer (S430). Referring back to FIG. 5C, when the light source is irradiated onto the reticle 500 to which the optical module 535 is attached, in the normal region II, the light source does not cause diffraction, as shown by the arrow of 'a3'. While it is irradiated without change, the light source passing through the first inclined plane 541 of the 'I' region where the overlay error is measured is diffracted at reference numerals 'a1' and 'a2' and shifted through the second inclined plane 543. Pass through the light path. Accordingly, the overlay error extended out of the field may compensate the registration of the reticle by moving the light source inside the field by the light source passing through the displaced optical path while passing through the optical module 535 of FIG. 5C. In this case, the optical module 535 selectively forms the inclined surfaces 541 and 543 only in the portion corresponding to the region I where the overlay error occurs, and corresponds to the region II corresponding to the normal region II in which the overlay error does not occur. By forming the flat surface 542, optical correction can be selectively performed only on the local region.

By introducing an optical module that can selectively perform optical correction only on the areas where overlay errors have occurred, overlay errors asymmetrically generated in the reticle, overlay errors generated in an asymmetric trapezoidal shape at the top and bottom, or on the quartz substrate of the reticle It is also applicable to the intrafield overlay error caused by applying the method of securing the linewidth uniformity by adjusting the linewidth CD in the field by adjusting the transmittance by irradiating the laser. Hereinafter, a description will be given with reference to FIGS. 6 and 7.

6 and 7 illustrate a method of correcting an overlay error generated in various forms by applying the optical module of the present invention. Referring to FIG. 6, which shows an overlay error generated in a trapezoidal shape, an overlay error is observed in a trapezoidal shape as an intrafield overlay error, which is an error caused by a shape in a field. The above-mentioned intrafield overlay error is based on the field 210 to be formed originally, the upper portion of the field 215 actually formed is reduced to the inside of the field as indicated by the first arrow (a), and the lower portion is the second arrow (b). As shown by), it can be seen that the overlay error occurs in the trapezoidal shape by extending out of the field. In this case, the correction method by the general linear analysis requires a different correction to the upper and lower, respectively, there is a problem that the correction is difficult. On the other hand, referring to the right side of Figure 6 applying the optical module of the present invention to the reticle, a portion of the optical module 625 disposed on the reticle 601 of the portion corresponding to the top of the field is shown by the first arrow ( As shown in a), the first inclined surface 630 is formed on the first plate 615, and the second inclined surface 631 is formed on the second plate 620 to expand the reduced portion inside the field. One slit 634 is formed. In addition, a portion of the optical module 625 disposed on the reticle 601 of the portion corresponding to the lower portion of the field is provided to reduce the portion extending out of the field, as indicated by the second arrow (b) in the left figure. A third inclined surface 632 is formed on the first plate 615, and a fourth inclined surface 633 is formed on the second plate 620 to form a second slit 635. Accordingly, the direction of the light source is changed by the first slit 634 at the upper part of the field, and the direction of the light source is changed by the second slit 635 at the lower part of the field. Therefore, different corrections may be performed on the upper and lower portions of the field where the overlay error occurs. Here, the parts not described in the drawings are the quartz substrate 600, the mask pattern 605 and the support 610 formed on the quartz substrate 600.

In addition, referring to FIG. 7, which shows an intrafield overlay error caused by applying a method of securing line width uniformity by adjusting line width (CD) in a field by irradiating a laser to a quartz substrate of a reticle and adjusting transmittance, As an error caused by an intrafield overlay, a reduced overlay error is observed at the top and bottom of the field based on a normal overlay configuration. In this case, as a general linear analysis, a correction is performed on the upper and lower portions of the field 800 and 805, but the correction may also be performed on the center portion 803 of the field having a normal overlay configuration. have. On the other hand, referring to the right drawing of Figure 7 applying the optical module of the present invention to the reticle, the optical module 725 disposed on the reticle 701 of the portion corresponding to the upper and lower portions of the field is the first arrow ( As shown by c) and the second arrow (d), first inclined surfaces 731 and 733 are formed on the first plate 715 and the second plate 720 is formed so as to expand the reduced portion inwardly of the field. Second inclined surfaces 732 and 734 are formed to form first slits 730 and 740. In addition, since a part of the optical module 725 disposed in the reticle 701 of the portion corresponding to the center portion 803 of the field has a normal overlay configuration, a first flat surface 736 is formed on the first plate 715. The second plate 720 is formed with a second slit 735 having a flat second surface 737. Accordingly, the direction of the light source is changed by the first slits 730 and 740 in the upper and lower portions 805 and 805 of the field, whereas in the central portion 803 of the field, the second surface has the flat surfaces 736 and 737. The slit 735 passes through the light source unchanged. Therefore, correction may be selectively performed only on the upper and lower portions of the field where the overlay error occurs. Here, the parts not described in the drawings are the quartz substrate 700, the mask pattern 705 and the support 710 formed on the quartz substrate 700.

500: reticle 510: mask pattern
500a: field 525: first plate
530: second plate 535: optical module
545: slit

Claims (8)

Measuring an overlay error of the reticle including the first pattern to be formed on the wafer;
Introducing an optical module including a slit on the reticle to change a path of a light source irradiated to a portion where the overlay error occurs; And
And disposing a reticle into which the optical module is introduced to the optical equipment and irradiating a light source to transfer a second pattern having an overlay error corrected to a wafer by a light source passing through a slit in which the path of the light source is changed. Overlay correction method. The method of claim 1,
The measuring of the overlay error may include measuring an alignment state of the first pattern;
Comparing the alignment of the first pattern with the alignment of the reference pattern to be formed on the wafer; And
And measuring a degree and a position at which the first pattern deviates from the alignment of the reference pattern and defining the residual value as a residual value. The method of claim 1,
The overlay error of the reticle is measured in the field of a rectangular field (overlay) correction method of the semiconductor device. The method of claim 3,
The overlay error measured by the field unit includes an overlay error in which the upper and lower portions of the field are asymmetric with each other, or an overlay error in which the upper and lower portions except the center of the field are symmetrically generated. Overlay correction method. The method of claim 1,
The optical module may include a first plate having a first inclined plane that primarily changes the path of the light source in a portion corresponding to the first area where the overlay error of the reticle is measured, and the first in the plane facing the first inclined plane. And a second plate having a second inclined surface that quadratically changes the path of the changed light source. The method of claim 1,
And the optical module forms a flat surface on the reticle where the overlay has a normal value. The method of claim 1,
And the optical module is directly attached to the reticle or attached to a stage of the optical equipment in which the reticle is disposed. The method of claim 1,
The transferring of the second pattern of which the overlay error is corrected may include correcting the path of the light source by selectively changing a portion of the reticle where the overlay error has occurred.
KR1020110013467A 2011-02-15 2011-02-15 Method for correction of overlay error in semiconductor device KR20120093723A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20160138778A (en) * 2015-05-26 2016-12-06 삼성전자주식회사 Methods of Revising an Overlay Correction Data
US11796923B2 (en) 2020-12-03 2023-10-24 Samsung Electronics Co., Ltd. Overlay correction method, method of evaluating overlay correction operation, and method of fabricating semiconductor device using the overlay correction method

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20160138778A (en) * 2015-05-26 2016-12-06 삼성전자주식회사 Methods of Revising an Overlay Correction Data
US11796923B2 (en) 2020-12-03 2023-10-24 Samsung Electronics Co., Ltd. Overlay correction method, method of evaluating overlay correction operation, and method of fabricating semiconductor device using the overlay correction method

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