JP2010073817A - Method for forming pattern and method for determining offset value - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pattern formation technique that is highly accurate and advantageous for position measurement. <P>SOLUTION: The method for forming a pattern includes: a first process including first lithography steps such as a film formation step, a first application step of applying a first resist, a first exposure step of exposing the first resist, a first development step of developing the first resist, and a first etching step of etching the film, thus forming a first edge group on the film that contains at least one first edge pair; and a second process including second lithography steps such as a second application step of applying a second resist, a second exposure step of exposing the second resist, a second development step of developing the second resist, and a second etching step of etching the film, thus forming a second edge group on the film that contains at least one second edge pair, wherein the first edge pair is composed of two first edges arranged at a position symmetrical relative to a first axis of symmetry and the second edge pair is composed of two second edges arranged at a position symmetrical relative to a second axis of symmetry. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pattern formation method and an offset value determination method.

  A manufacturing process of a device such as a semiconductor device includes repetition of a lithography process. The lithography process includes, for example, formation of a film on a wafer (substrate), application of a resist (photosensitive agent) on the film, exposure of the resist, development of the resist (that is, formation of a resist pattern) and Etching the film can be included.

  FIG. 7 is a view showing a schematic configuration of an exposure apparatus used in an exposure process for manufacturing a device such as a semiconductor device. In the exposure apparatus, the reticle (original) R is illuminated by an illumination system (not shown), and the pattern of the reticle is projected onto the wafer (substrate) W on the wafer stage STG by the projection optical system UL. Thereby, the resist coated on the wafer W is exposed, and a latent image is formed on the resist. The resist is developed in a development process, whereby a resist pattern is formed. Using this resist pattern as a mask, the underlying film can be etched.

  In the lithography process, the alignment mark WM is formed together with the device pattern. The alignment mark WM is observed using the off-axis scope OAS, and its position is detected. In the off-axis scope OAS, the alignment mark WM is illuminated by the illumination unit IL via the imaging optical system L1. The reflected light from the alignment mark WM forms an image of the alignment mark WM on the imaging surface of the imaging unit S via the beam splitter BS and the imaging optical system L2. The position of the alignment mark WM is detected by performing image processing on the image of the alignment mark WM imaged by the imaging unit S.

  In recent years, double patterning that forms a higher resolution pattern without changing the configuration of the apparatus has attracted attention. In the double patterning, a first edge which is a part of a closed figure such as a line is formed by a first lithography process, and a second edge which is another part of the edge of the closed figure is formed by a second lithography process. Technology to form. When aligning the pattern of the next layer with the pattern of the layer formed by the double patterning, it is necessary to detect the position of the alignment mark including the first edge and the second edge.

  FIG. 8 is a diagram for explaining formation of alignment marks by double patterning and detection signals of the alignment marks. FIG. 8A is a plan view of an alignment mark WM that is a pattern including marks M1, M2, M3, and M4. 8A to 8F are schematic cross-sectional views showing each step of the pattern forming method.

  8B and 8C are diagrams illustrating the first step. In the first step, the first edge is formed by a first lithography step. In the first lithography process, the film F is formed on the wafer W, the first application for applying the first resist RG1 on the film F, the first exposure for exposing the first resist RG1, and the first resist RG1 are developed. First development and first etching for etching the film F are included. FIG. 8B shows the state of the first exposure executed using the first reticle R1, and FIG. 8C shows the first exposure executed using the first resist pattern RGP1 formed by the first development as a mask. A state after the etching is schematically shown. In the first step, the film F is patterned into a film F ′. On the film F ′, left edges of the marks M1, M2, M3, and M4 are formed as first edges.

  8D, 8E, and 8F are diagrams for explaining the second step. In the second step, the second edge is formed by a second lithography step. In the second lithography step, the second application for applying the second resist RG2 on the film F ′, the second exposure for exposing the second resist RG2, the second development for developing the second resist RG2, and the film F ′ are etched. A second etch. FIG. 8D shows a state after the second etching performed using the second resist pattern RGP2 formed by the second development as a mask, and FIG. 8F shows the mark after the removal of the second resist pattern RGP2. M1, M2, M3, and M4 are schematically shown. In the second step, the film F ′ is patterned into a film F ″ having marks M1, M2, M3, and M4. In the film F ″, the right edge of each of the marks M1, M2, M3, and M4 is the first. It is formed as two edges.

  The alignment mark WM including the marks M1, M2, M3, and M4 is observed by the off-axis scope OAS, and the position of the alignment mark WM is detected.

  FIG. 8G shows a waveform of a mark signal (mark signal) obtained by AD-converting a signal output from the imaging unit S of the off-axis scope OAS and converting it to a one-dimensional waveform. The image processing unit extracts the processing regions W1 to W4 from the waveform of the mark signal, performs template matching on the waveforms of the processing regions W1 to W4, and obtains the positions posX1 to posX4 of the marks M1 to M4. The image processing unit further calculates the position posXave of the alignment mark WM by averaging posX1 to posX4.

The alignment mark WM including the marks M1, M2, M3, and M4 illustrated in FIG. 8F includes a first edge and a second edge. Therefore, a position detection result is obtained in which the alignment accuracy in the first step including the first exposure and the alignment accuracy in the second step including the second exposure are averaged.
JP 2008-96991 A

  When the exposure conditions and / or etching conditions have changed in the first step and the second step, the edge shape formed in the first step and the second step are formed as illustrated in FIG. 8G. The edge shape can be different. As a result, the waveform of the mark signal, which is the detection signal of the alignment mark WM, becomes asymmetric, and template matching is not performed correctly. )) May occur.

  The present invention has been made with the above problem recognition as an opportunity, and for example, an object of the present invention is to provide a pattern forming technique advantageous for highly accurate position measurement.

  A first aspect of the present invention relates to a pattern forming method for forming a pattern including a plurality of edges on a substrate. The pattern forming method includes forming a film, applying a first resist, applying the first resist, The first edge group including at least one first edge pair is formed by a first lithography process including a first exposure for exposing one resist, a first development for developing the first resist, and a first etching for etching the film. A first step of forming a film; a second application for applying a second resist; a second exposure for exposing the second resist; a second development for developing the second resist; and a second etching for etching the film. Forming a second edge group including at least one second edge pair on the film by a second lithography process including, the first edge pair including a first pair. Consists of two first edges arranged in symmetrical positions with respect to the axis, the second edge pair is comprised of two second edges arranged in symmetrical positions with respect to the second axis of symmetry.

  According to a second aspect of the present invention, there is provided a pattern forming method for forming a pattern including a plurality of edges on a substrate. The pattern forming method includes forming a film, applying a first resist, applying the first resist, A first step of forming a plurality of first edges on the film by a lithography process including a first exposure for exposing one resist, a first development for developing the first resist, and a first etching for etching the film; A plurality of second edges are formed by a lithography process including a second application for applying two resists, a second exposure for exposing the second resist, a second development for developing the second resist, and a second etching for etching the film. Forming a first line, a second line, and a third line, thereby forming a first line, a second line, and a third line. The second line is disposed, and each of the first line, the second line, and the third line includes one first edge and one second edge, and the first line and the second line The two lines are arranged at positions symmetrical to each other with respect to the first symmetry axis, and the second line and the third line are arranged at positions symmetrical to each other with respect to the second symmetry axis.

  According to a third aspect of the present invention, there is provided an offset value determining method, wherein a pattern including a first line, a second line, and a third line is formed by the pattern forming method according to the second aspect; Measuring a first distance that is a distance between the position of one line and the position of the second line, and a second distance that is a distance between the position of the second line and the position of the third line; Calculating a measurement error at each position of the pattern including the first line, the second line, and the third line as an offset value based on the first distance and the second distance.

  According to the present invention, for example, a pattern forming technique advantageous for highly accurate position measurement is provided.

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

[First Embodiment]
In the pattern forming method according to the first embodiment of the present invention, a pattern including a plurality of edges is formed on a substrate. The pattern forming method includes a first step and a second step.

  In the first step, a first edge group including at least one first edge pair is formed on the film by a first lithography step. The first lithography step includes forming a film, first coating for applying a first resist, first exposure for exposing the first resist, first development for developing the first resist, and first etching for etching the film. 1 etching is included.

  In the second step, a second edge group including at least one second edge pair is formed on the film by a second lithography step. The second lithography process includes a second application for applying a second resist, a second exposure for exposing the second resist, a second development for developing the second resist, and a second etching for etching the film.

  Here, the first edge pair is composed of two first edges arranged at positions symmetric with respect to the first symmetry axis, and the second edge pair is composed of two positions arranged at positions symmetrical with respect to the second symmetry axis. Consists of the second edge.

  In the manufacture of devices such as semiconductor devices, in the first step, a part of the device pattern is formed in addition to the first edge group, and in the second step, in addition to the second edge group, the device pattern Some edges may be formed.

  In this pattern forming method, in addition to double patterning, a part of a plurality of marks constituting an alignment mark of one layer is formed in a first sography process, and the other part of the plurality of marks is formed in a first pattern. It can also be applied to a method of forming by two lithography processes.

  FIG. 1 is a diagram for explaining a pattern forming method according to a preferred embodiment of the present invention. FIG. 1A is a plan view of an alignment mark WM that is a pattern including marks M1, M2, M3, and M4. 1A to 1F are schematic cross-sectional views showing each step of the pattern forming method in the embodiment.

  1B and 1C are diagrams illustrating the first step. In the first step, a first edge group including at least one first edge pair ep1 is formed by a first lithography step. One first edge pair ep1 is composed of two first edges e1 arranged at positions symmetrical with respect to the symmetry axis (first symmetry axis) s1.

  In the first lithography process, the film F is formed on the wafer W, the first application for applying the first resist RG1 on the film F, the first exposure for exposing the first resist RG1, and the first exposure for developing the first resist RG1. 1 development and the 1st etching which etches the film | membrane F are included. FIG. 1B shows the state of the first exposure executed using the first reticle R1, and FIG. 1C shows the first exposure executed using the first resist pattern RGP1 formed by the first development as a mask. A state after the etching is schematically shown. In the first step, the film F is patterned into a film F ′. A first edge e1 is formed on each of the marks M1, M2, M3, and M4 on the film F ′.

  1D, 1E, and 1F are diagrams for explaining the second step. In the second step, a second edge group including at least one second edge pair ep2 is formed by a second lithography step. One second edge pair ep2 is composed of two second edges e2 arranged at symmetrical positions with respect to the symmetry axis (second symmetry axis) s1. In the embodiment shown in FIG. 1, the second symmetry axis for the second edge pair ep2 is common to the first symmetry axis for the first edge pair ep1.

  In the second lithography step, the second application for applying the second resist RG2 onto the film F ′, the second exposure for exposing the second resist RG2, the second development for developing the second resist RG2, and the film F ′ are etched. Including a second etch. FIG. 1D shows a state after the second etching performed using the second resist pattern RGP2 formed by the second development as a mask, and FIG. 1F shows the mark after the removal of the second resist pattern RGP2. M1, M2, M3, and M4 are schematically shown. In the second step, the film F ′ is patterned into a film F ″ having marks M1, M2, M3, and M4. The film F ″ includes a second edge e2 on each of the marks M1, M2, M3, and M4. Is formed.

  FIG. 1 (g) shows a waveform of a mark signal (mark signal) obtained by AD-converting a signal output from the imaging unit S of the off-axis scope OAS and converting the signal into a one-dimensional waveform. The image processing unit extracts the processing regions W1 to W4 from the waveform of the mark signal, performs template matching on the waveforms of the processing regions W1 to W4, and obtains the positions posX1 to posX4 of the marks M1 to M4. The image processing unit further calculates the position posXave of the alignment mark WM by averaging posX1 to posX4.

  In the embodiment shown in FIG. 1, two first edges e1 constituting the first edge pair ep1 are arranged at symmetrical positions with respect to the first symmetry axis s1, and two second edges e2 constituting the second edge pair ep2 are arranged. Are arranged at positions symmetrical with respect to the second coping axis common to the first symmetry axis s1. By forming the marks M1 to M4 having such a structure, errors dX1 to dX4 when the positions posX1 to posX4 of the marks M1 to M4 are obtained by template matching can be reduced. Even if the exposure conditions and / or the etching conditions change between the first process and the second process, as illustrated in FIG. 1G, the processing center corresponding to each first symmetry axis s1. This is because a mark signal having a symmetric waveform can be obtained. In the example shown in FIG. 1G, the slopes of the waveform corresponding to the first edge e1 and the waveform corresponding to the second edge e2 are different.

  In the embodiment shown in FIG. 1, the first edge group includes a plurality of first edge pairs ep1 and the second edge group includes a plurality of second edge pairs ep2. As Wm, a pattern including a plurality of marks M1 to M4 is formed on the film F. Each mark includes a first edge pair composed of two first edges arranged at positions symmetrical with respect to the symmetry axis s1 for the mark, and two second edges arranged at positions symmetrical with respect to the symmetry axis s1. And a second edge pair.

  In the embodiment shown in FIG. 1, the plurality of first edge pairs ep1 and the plurality of second edge pairs ep2 included in the plurality of marks M1 to M4 are arranged at symmetrical positions with respect to the common symmetry axis cs. Therefore, the error dXave (= (1/4) ΣdXi (i = 1 to 4)) of the position posXave of the alignment mark WM calculated based on the positions posX1 to posX4 of the marks M1 to M4 is reduced. Here, when only the error in template matching is considered, the plurality of first edge pairs ep1 and the plurality of second edge pairs ep2 included in the plurality of marks M1 to M4 are arranged at symmetrical positions with respect to the common symmetry axis cs. There is no need. However, since the imaging optical systems L1 and L2 usually have slight aberrations, the plurality of first edge pairs ep1 and the plurality of first edge pairs ep1 and the plurality of the plurality of first edge pairs ep with respect to the common symmetry axis cs that is the entire center of the alignment mark WM including the marks M1 to M4. The second edge pair ep2 is preferably arranged at a symmetrical position.

  Also in the embodiment shown in FIG. 2, the two first edges e2 constituting the first edge pair ep1 are arranged at positions symmetrical with respect to the first symmetry axis s1, and the two second edges e2 constituting the second edge pair ep2 are used. Are arranged at positions symmetrical with respect to the second coping axis common to the first symmetry axis s1. Therefore, also in the embodiment shown in FIG. 2, the errors dX1 to dX4 when the positions posX1 to posX4 of the marks M1 to M4 are obtained by template matching can be reduced.

  However, in the embodiment shown in FIG. 2, the plurality of first edge pairs ep1 and the plurality of second edge pairs ep2 included in the plurality of marks M1 to M4 are not arranged at symmetrical positions with respect to the common symmetry axis cs. Therefore, if the imaging optical systems L1 and L2 have aberration, the error dXave (= (1/4)) of the position posXave of the alignment mark WM calculated based on the positions posX1 to posX4 of the marks M1 to M4. ΣdXi (i = 1 to 4)) can be increased.

  In this respect, the embodiment shown in FIG. 1 is superior to the embodiment shown in FIG.

  FIG. 3 is an embodiment having the same effects as the embodiment shown in FIG. At the mark marks M1 and M4, in the first step, the first edge e1 is formed outside the two lines constituting the mark, and in the second step, the second edge is located inside the two lines constituting the mark. e2 is formed. When the marks M2 and M3 are reached, the first edge e1 is formed inside the two lines constituting the mark in the first step, and the second edge e2 is formed outside the two lines constituting the mark in the second step. Is formed.

  In the embodiment shown in FIG. 3, the two first edges e1 constituting the first edge pair ep1 and the two second edges e2 constituting the second edge pair ep2 are arranged at symmetrical positions with respect to the first symmetry axis s1. ing. In addition, a plurality of first edge pairs ep1 and a plurality of second edge pairs ep2 are arranged at symmetrical positions with respect to the common symmetry axis cs that is the entire center of the alignment mark WM including the marks M1 to M4. Therefore, in the embodiment shown in FIG. 3, the template matching error can be reduced, and dX1≈−dX4, dX2≈−dX3 even when there are aberrations in the imaging optical systems L1, L2, etc. The measurement error of the alignment mark WM can be reduced.

  The embodiment shown in FIGS. 1 to 3 exemplifies a pattern forming method by double patterning. In these embodiments, two parallel sides of one line are constituted by one of the two first edges constituting the first edge pair and one of the two second edges constituting the second edge pair. In addition, the other of the two first edges constituting the first edge pair and the other of the two second edges constituting the second edge pair constitute two parallel sides of another one line.

  In the embodiment shown in FIG. 4 and FIG. 5, a part of the plurality of marks constituting the alignment mark of one layer is formed in the first somography process, and the other part of the plurality of marks is formed. It is formed by the second lithography process.

  In the embodiment shown in FIG. 4, one side h1 of one line is constituted by one of the two first edges e1 ′ constituting the first edge pair ep1 ′, and the other one of the two first edges e1 ′. One side h2 of another one line is configured. In the embodiment shown in FIG. 4, one side h3 of one line is constituted by one of the two first edges e2 ′ constituting the second edge pair ep2 ′, and the two second edges e2 ′ The other side constitutes one side h4 of the other one line.

  Similarly, one of the two first edges e1 "constituting the first edge pair ep1" constitutes another one side h5 of one line, and the other of the two first edges e1 "constitutes another 1 Another one side h6 of one line is configured, and another one side h7 of one line is configured by one of the two first edges e2 "configuring the second edge pair ep2". The other of the two second edges e2 "constitutes another side h8 of the other line.

  4B and 4C are diagrams for explaining the first step. In the first process, a first edge group including a first edge pair ep1 ′ and ep1 ″ as at least one first edge pair is formed by a first lithography process. One first edge pair ep1 ′ is a first edge pair. It is composed of two first edges e1 ′ arranged at positions symmetric with respect to the symmetry axis s1. The other one first edge pair ep1 ″ is two pieces arranged at positions symmetrical with respect to the first symmetry axis s1. It is composed of a first edge e1 ".

  In the first lithography process, the film F is formed on the wafer W, the first application for applying the first resist RG1 on the film F, the first exposure for exposing the first resist RG1, and the first exposure for developing the first resist RG1. 1 development and the 1st etching which etches the film | membrane F are included. FIG. 4B shows the state of the first exposure performed using the first reticle R1, and FIG. 4C shows the first exposure performed using the first resist pattern RGP1 formed by the first development as a mask. A state after the etching is schematically shown. In the first step, the film F is patterned into a film F ′. In the film F ′, a first edge pair ep1 ′ composed of two first edges e1 ′ and a first edge pair ep1 ″ composed of two first edges e1 ″ are formed for each of the marks M1 and M4. ing.

  4D, 4E, and 4F are diagrams for explaining the second step. In the second step, a second edge group including the second edge pair ep2 ′ and ep2 ″ as at least one second edge pair is formed by the second lithography step. One second edge pair ep2 ′ has a second symmetry. It is composed of two second edges e2 ′ arranged at positions symmetrical with respect to the axis s2. The other second edge pair ep2 ″ is two second edges arranged at positions symmetrical with respect to the second symmetry axis s2. 2 edges e2 ".

  In the second lithography step, the second application for applying the second resist RG2 onto the film F ′, the second exposure for exposing the second resist RG2, the second development for developing the second resist RG2, and the film F ′ are etched. Including a second etch. FIG. 4D shows the state after the second etching performed using the second resist pattern RGP2 formed by the second development as a mask, and FIG. 4F shows the mark after the removal of the second resist pattern RGP2. M1, M2, M3, and M4 are schematically shown. In the second step, the film F ′ is patterned into a film F ″ having marks M1, M2, M3, and M4. The film F ″ includes two second edges for each of the marks M2 and M3. A first edge pair ep2 ′ composed of e2 ′ and a first edge pair ep2 ″ composed of two second edges e2 ″ are formed.

  FIG. 4G shows a waveform of a mark signal (mark signal) obtained by AD-converting a signal output from the imaging unit S of the off-axis scope OAS and converting the signal into a one-dimensional waveform. The image processing unit extracts the processing regions W1 to W4 from the waveform of the mark signal, performs template matching on the waveforms of the processing regions W1 to W4, and obtains the positions posX1 to posX4 of the marks M1 to M4. The image processing unit further calculates the position posXave of the alignment mark WM by averaging posX1 to posX4.

  Also in the embodiment shown in FIG. 4, a plurality of first edge pairs ep1 ′, ep1 ″ and a plurality of second edge pairs ep2 ′, ep2 ″ with respect to the common symmetry axis cs that is the entire center of the alignment mark WM composed of the marks M1 to M4. Are arranged at symmetrical positions.

  In the embodiment shown in FIG. 5, two parallel edges 11 and 12 of one line are constituted by two first edges e1 constituting the first edge pair ep1. Further, two parallel edges h13 and h14 of another line are constituted by the two second edges e2 constituting the second edge pair ep2.

  5B and 5C are diagrams illustrating the first step. In the first step, a first edge group including at least one first edge pair ep1 is formed by a first lithography step. One first edge pair ep1 is composed of two first edges e1 arranged at positions symmetrical with respect to the first symmetry axis s1.

  In the first lithography process, the film F is formed on the wafer W, the first application for applying the first resist RG1 on the film F, the first exposure for exposing the first resist RG1, and the first exposure for developing the first resist RG1. 1 development and the 1st etching which etches the film | membrane F are included. FIG. 5B shows a state of the first exposure executed using the first reticle R1, and FIG. 5C shows a first exposure executed using the first resist pattern RGP1 formed by the first development as a mask. A state after the etching is schematically shown. In the first step, the film F is patterned into a film F ′. In the film F ′, a first edge pair ep1 including two first edges e1 is formed for each of the marks M1 and M4.

  FIGS. 5D, 5E, and 5F are diagrams for explaining the second step. In the second step, a second edge group including at least one second edge pair ep2 is formed by a second lithography step. One second edge pair ep2 is composed of two second edges e2 arranged at positions symmetrical with respect to the second symmetry axis s2.

  In the second lithography process, the second application for applying the second resist RG2 onto the film F ′, the second exposure for exposing the second resist RG2, the second development for developing the second resist RG2, and the film F ′ are etched. Including a second etch. FIG. 5D shows a state after the second etching performed using the second resist pattern RGP2 formed by the second development as a mask, and FIG. 5F shows the mark after the removal of the second resist pattern RGP2. M1, M2, M3, and M4 are schematically shown. In the second step, the film F ′ is patterned into a film F ″ having marks M1, M2, M3, and M4. The film F ″ includes two second edges for each of the marks M2 and M3. A second edge pair ep2 made of e2 is formed.

  FIG. 5G shows a waveform of a mark signal (mark signal) obtained by AD-converting a signal output from the imaging unit S of the off-axis scope OAS and converting it to a one-dimensional waveform. The image processing unit extracts the processing regions W1 to W4 from the waveform of the mark signal, performs template matching on the waveforms of the processing regions W1 to W4, and obtains the positions posX1 to posX4 of the marks M1 to M4. The image processing unit further calculates the position posXave of the alignment mark WM by averaging posX1 to posX4.

  Also in the embodiment shown in FIG. 5, the plurality of first edge pairs ep1 and the plurality of second edge pairs are arranged at symmetrical positions with respect to the common symmetry axis cs that is the entire center of the alignment mark WM including the marks M1 to M4. .

  Also in the embodiments shown in FIGS. 4 and 5, the template matching error can be reduced. Further, even when there is an aberration in the imaging optical systems L1, L2, etc., since dX1≈−dX4, dX2≈−dX3, the measurement error of the alignment mark WM can be reduced.

  In the embodiment shown in FIGS. 1 to 5, it is preferable that the number of first edges is equal to the number of second edges. Accordingly, the position of the alignment mark WM can be calculated without weighting the influence of the first edge on the measurement result and the influence of the second edge on the measurement result.

[Second Embodiment]
The second embodiment of the present invention provides an offset value determination method for correcting a measurement error due to a difference in cross-sectional shape between a first edge and a second edge. Here, the difference in cross-sectional shape between the first edge and the second edge may be caused by different exposure conditions and / or etching conditions between the first process and the second process. The offset value determination method according to the second embodiment of the present invention includes a step of forming a pattern including a first line, a second line, and a third line.

  FIG. 6 is a diagram for explaining a pattern formation step (formation method) in the second embodiment of the present invention. This pattern forming method forms a pattern including a plurality of edges on a substrate, and includes a first step and a second step.

  In the first step, film formation, first application for applying a first resist, first exposure for exposing the first resist, first development for developing the first resist, and first etching for etching the film are performed. A plurality of first edges are formed in the film by a lithography process including.

  In the second step, a lithography process including a second application for applying a second resist, a second exposure for exposing the second resist, a second development for developing the second resist, and a second etching for etching the film. A plurality of second edges are formed in the film. Thereby, a first line (mark M1), a second line (mark M2), and a third line (mark M3) are formed.

  Here, the second line (M2) is disposed between the first line (M1) and the third line (M3), and the first line (M1), the second line (M2), and the third line (M3). Are each constituted by one first edge e1 and one second edge e2. In addition, the first line (M1) and the second line (M2) are disposed at symmetrical positions with respect to the first symmetry axis s1, and the second line (M2) and the third line (M3) They are arranged symmetrically with respect to the symmetry axis s2.

  FIG. 6A is a plan view of a test pattern TP for determining an offset value, which is a pattern including marks M1, M2, and M3. FIGS. 6A to 6F are schematic cross-sectional views showing each step of the pattern forming method in the embodiment.

  6B and 6C are diagrams illustrating the first step. In the first step, three first edges e1 are formed as a plurality of first edges by the first lithography step.

  In the first lithography process, the film F is formed on the wafer W, the first application for applying the first resist RG1 on the film F, the first exposure for exposing the first resist RG1, and the first exposure for developing the first resist RG1. 1 development and the 1st etching which etches the film | membrane F are included. FIG. 6B shows the state of the first exposure executed using the first reticle R1, and FIG. 6C shows the first exposure executed using the first resist pattern RGP1 formed by the first development as a mask. A state after the etching is schematically shown. In the first step, the film F is patterned into a film F ′. In the film F ′, a first edge e1 is formed on the left side of the first line (M1), the right side of the second line (M2), and the left side of the third line (M3).

  6D, 6E, and 6F are diagrams for explaining the second step. In the second step, three second edges e2 are formed as a plurality of second edges by the second lithography step, whereby the first line (M1), the second line (M2), and the third line (M3) are formed. Form.

  In the second lithography step, the second application for applying the second resist RG2 onto the film F ′, the second exposure for exposing the second resist RG2, the second development for developing the second resist RG2, and the film F ′ are etched. Including a second etch. FIG. 6D schematically shows a state after the second etching performed using the second resist pattern RGP2 formed by the second development as a mask. FIG. 6F schematically shows the first line (M1), the second line (M2), and the third line (M3) after the removal of the second resist pattern RGP2. In the second step, the film F ′ is patterned to become a film F ″ having the first line (M1), the second line (M2), and the third line (M3). The film F ″ includes the first line. A second edge e2 is formed on each of (M1), the second line (M2), and the third line (M3). As described above, the first line (M1) and the second line (M2) are disposed symmetrically with respect to the first symmetry axis s1, and the second line (M2) and the third line (M3) are , Are arranged at positions symmetrical to each other with respect to the second symmetry axis s2.

  FIG. 6G shows a waveform of a mark signal (mark signal) obtained by AD-converting a signal output from the imaging unit S of the off-axis scope OAS and converting the signal into a one-dimensional waveform. The image processing unit extracts the processing areas W1 to W3 from the waveform of the mark signal, performs template matching on the waveforms of the processing areas W1 to W3, and performs the first line (M1), the second line (M2), and the first line. The positions posX1 to posX3 of the three lines (M3) are obtained.

  The calculation unit (not shown) (the processing by the calculation unit may be incorporated in the image processing unit) is based on the positions posX1 to posX3, the first line (M1), the second line (M2) and the second line. A measurement error at each position of the pattern including three lines (M3) is calculated as an offset value. When manufacturing a device, a measurement result obtained by alignment measurement may be corrected with an offset value and used.

  posX1 to posX3 include measurement errors dX1 to dX3, respectively, but when the cause of the measurement error is only the difference between the exposure condition and the etching condition, the difference between the measurement errors dX1 to dX3 is only a difference in sign, dX1 = −dX2 = dX3 holds. Accordingly, the distance (first distance) between the position of the first line (M1) and the position of the second line (M2) is P [M1, M2], and the position of the second line (M2) and the third line (M3). ) If the distance (second distance) to the position of P) is P [M2, M3], the following equation is established. The “design value” is a design value of the distance between the centers of the two corresponding lines.

P [M1, M2] = posX2-posX1 = design value + dX2-dX1
P [M2, M3] = posX3-posX2 = design value + dX3-dX2
Here, when dX1 = −dX2 = dX3 = offset, the following equation is obtained.

P [M2, M3] -P [M1, M2] = (dX3-dX2)-(dX2-dX1)
P [M2, M3] −P [M1, M2] = 4 × offset
offset = (P [M2, M3] −P [M1, M2]) / 4
The calculation unit calculates a measurement error, that is, an offset value offset according to the above equation.

  If the positions of the first line (M1), the second line (M2), and the third line (M3) of the test pattern TP are the M1, M2, and M3 positions, they are given by the following equations.

M1 position = posX1 + offset
M2 position = posX2-offset
M3 position = posX3 + offset
The offset value can be determined through measurement of a test pattern (offset measurement mark) on the wafer at the beginning of a lot, for example. Alternatively, the offset value may be determined by including a test pattern in the alignment mark and measuring the test pattern every time the alignment mark is measured.

It is a figure explaining the pattern formation method in suitable embodiment of this invention. It is a figure explaining the pattern formation method in suitable embodiment of this invention. It is a figure explaining the pattern formation method in suitable embodiment of this invention. It is a figure explaining the pattern formation method in suitable embodiment of this invention. It is a figure explaining the pattern formation method in suitable embodiment of this invention. It is a figure explaining the pattern formation method for the determination of the offset value in suitable embodiment of this invention. It is a figure which shows schematic structure of the exposure apparatus used in the exposure process for manufacturing devices, such as a semiconductor device. It is a figure explaining the pattern formation method.

Claims (10)

A pattern forming method for forming a pattern including a plurality of edges on a substrate,
A first lithography process including a film formation, a first application for applying a first resist, a first exposure for exposing the first resist, a first development for developing the first resist, and a first etching for etching the film Forming a first edge group including at least one first edge pair on the film by:
At least one second lithography process including a second application for applying a second resist, a second exposure for exposing the second resist, a second development for developing the second resist, and a second etching for etching the film. Forming a second edge group including a second edge pair on the film,
The first edge pair is composed of two first edges arranged at positions symmetric with respect to the first symmetry axis, and the second edge pair is arranged with two first edges arranged at positions symmetrical with respect to the second symmetry axis. Composed of two edges,
The pattern formation method characterized by the above-mentioned. The first symmetry axis and the second symmetry axis are common.
The pattern forming method according to claim 1. The first edge group includes a plurality of first edge pairs, and the second edge group includes a plurality of second edge pairs;
A pattern consisting of a plurality of marks is formed on the film through the first step and the second step, and each mark is composed of two first edges arranged at positions symmetrical with respect to the symmetry axis of the mark. A first edge pair, and a second edge pair composed of two second edges arranged at positions symmetrical with respect to the symmetry axis,
The plurality of first edge pairs and the plurality of second edge pairs included in the plurality of marks are arranged at symmetrical positions with respect to a common symmetry axis.
The pattern forming method according to claim 1. Two parallel sides of one line are constituted by one of the two first edges constituting the first edge pair and one of the two second edges constituting the second edge pair, and the first edge pair The other of the two first edges constituting the second edge and the other of the two second edges constituting the second edge pair constitute two parallel sides of one other line,
The pattern formation method of any one of Claims 1 thru | or 3 characterized by the above-mentioned. One side of one line is constituted by one of the two first edges constituting the first edge pair, and one of the other one line is constituted by the other of the two first edges constituting the first edge pair. Two sides are composed,
One side of one line is constituted by one of the two second edges constituting the second edge pair, and one of the other one line is constituted by the other of the two second edges constituting the second edge pair. One side is composed,
The pattern forming method according to claim 1, wherein the pattern forming method is a pattern forming method. Two parallel edges of one line are constituted by two first edges constituting the first edge pair, and two parallel edges of another line are constituted by two second edges constituting the second edge pair. One side is composed,
The pattern formation method of any one of Claims 1 thru | or 3 characterized by the above-mentioned. The number of the first edges is equal to the number of the second edges;
The pattern forming method according to claim 1, wherein: Forming the edge of a part of the device pattern in addition to the first edge group in the first step, and forming the other part of the edge of the device pattern in addition to the second edge group in the second step;
The pattern forming method according to claim 1, wherein the pattern forming method is a pattern forming method. A pattern forming method for forming a pattern including a plurality of edges on a substrate,
A plurality of lithography processes including a film formation, a first application for applying a first resist, a first exposure for exposing the first resist, a first development for developing the first resist, and a first etching for etching the film. Forming a first edge of the film on the film;
A plurality of second edges by a lithography process including a second application for applying a second resist, a second exposure for exposing the second resist, a second development for developing the second resist, and a second etching for etching the film. A second step of forming a first line, a second line and a third line on the film,
The second line is disposed between the first line and the third line, and each of the first line, the second line, and the third line includes one first edge and one second Composed of edges and
The first line and the second line are disposed at positions symmetrical with respect to the first symmetry axis, and the second line and the third line are disposed at positions symmetrical with respect to the second symmetry axis. Yes,
The pattern formation method characterized by the above-mentioned. A method for determining an offset value,
Forming a pattern including a first line, a second line, and a third line by the pattern forming method according to claim 9;
Measuring a first distance that is a distance between the position of the first line and the position of the second line, and a second distance that is a distance between the position of the second line and the position of the third line; ,
Calculating a measurement error at each position of the pattern including the first line, the second line, and the third line as an offset value based on the first distance and the second distance;
A method for determining an offset value.

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