Periodic semiconductor device offset metrology system and method

Abstract

The present invention discloses an offset metrology system and method that can be used in the manufacture of semiconductor devices, wherein the multilayer semiconductor device comprises: a first periodic structure having a first spacing along a first axis, the first periodic structure being formed together with a first layer of the multilayer semiconductor device; a second periodic structure having a second spacing along a second axis, the second axis being non-parallel to the first axis, the second periodic structure being formed together with the first layer of the multilayer semiconductor device; and a third periodic structure having a third spacing along a third axis, the third axis being non-parallel to the first axis and the third axis being non-parallel to the second axis, the third periodic structure being formed together with the second layer of the multilayer semiconductor device. , the third periodic structure and the first periodic structure and the second periodic structure overlap each other, and the offset metrology system and method include: generating a single image of the first periodic structure, the second periodic structure and the third periodic structure, thereby providing an aggregate signal; extracting a first component from the aggregate signal, the first component being attributed to the first periodic structure; extracting a second component from the aggregate signal, the second component being attributed to the second periodic structure; extracting a third component from the aggregate signal, the third component being attributed to the third periodic structure; and analyzing the first component, the second component and the third component to determine the offset between the first layer and the second layer.

Description

[0001] Citations of Related Applications

[0002] Reference is hereby made to the following patents and patent applications of the applicant that are related to the subject matter of the present application, the disclosures of which are hereby incorporated herein by reference:

[0003] U.S. Patent No. 7,274,814, entitled “OVERLAY MARKS, METHODS OF OVERLAY MARK DESIGN AND METHODS OF OVERLAY MEASUREMENTS”;

[0004] U.S. Patent No. 9,093,458, entitled “DEVICECORRELATED METROLOGY (DCM) FOR OVL WITH EMBEDDED SEM STRUCTURE OVERLAY TARGETS”;

[0005] U.S. Patent No. 9,214,317, entitled “SYSTEM AND METHOD OF SEM OVERLAYMETROLOGY”;

[0006] U.S. Patent No. 9,476,698, entitled “PERIODIC PATTERNS AND TECHNIQUE TO CONTROL MISALIGNMENT BETWEEN TWO LAYERS”; and

[0007] U.S. Published Patent Application No. 2016 / 0253450, entitled “METROLOGY USING OVERLAY AND YIELDCRITICAL PATTERNS” Technical Field

[0008] The present invention generally relates to offset measurement in semiconductor device fabrication. Background Art

[0009] Various methods and systems are known for measuring drift in semiconductor device fabrication. Summary of the invention

[0010] The present invention seeks to provide improved methods and systems for measuring excursions in semiconductor device fabrication.

[0011] Therefore, according to a preferred embodiment of the present invention, there is provided a method of offset metrology for measuring offset in the manufacture of a multilayer semiconductor device, the multilayer semiconductor device comprising: a first periodic structure having a first pitch along a first axis, the first periodic structure being formed together with a first layer of the multilayer semiconductor device; a second periodic structure having a second pitch along a second axis, the second axis being non-parallel to the first axis, the second periodic structure being formed together with the first layer of the multilayer semiconductor device; and a third periodic structure having a third pitch along a third axis, the third axis being non-parallel to the first axis and the third axis being non-parallel to the second axis, the third periodic structure being formed together with the multilayer semiconductor device. The first periodic structure and the second periodic structure are formed together, the third periodic structure and the first periodic structure and the second periodic structure overlap each other, and the offset metrology method includes: generating a single image of the first periodic structure, the second periodic structure and the third periodic structure, thereby providing an aggregate signal; extracting a first component from the aggregate signal, the first component being attributed to the first periodic structure; extracting a second component from the aggregate signal, the second component being attributed to the second periodic structure; extracting a third component from the aggregate signal, the third component being attributed to the third periodic structure; and analyzing the first component, the second component and the third component to determine the offset between the first layer and the second layer.

[0012] According to a preferred embodiment of the invention, said single image is generated using a scanning electron microscope using a field of view having a length and an area.Preferably, said aggregate signal comprises contributions from the entire said area.

[0013] Preferably, extracting the first component from the aggregate signal comprises considering only a portion of the aggregate signal located along the first axis. Preferably, extracting the second component from the aggregate signal comprises considering only a portion of the aggregate signal located along the second axis. Preferably, extracting the third component from the aggregate signal comprises considering only a portion of the aggregate signal located along the third axis.

[0014] According to a preferred embodiment of the present invention, the method further comprises: generating clean first periodic structure data; generating clean second periodic structure data; and generating clean third periodic structure data.

[0015] According to a preferred embodiment of the present invention, the clean first periodic structure data is a function of the first component and the first pitch. Alternatively, according to a preferred embodiment of the present invention, the clean first periodic structure data is a function of the first component, the first pitch and harmonics of the first pitch.

[0016] According to a preferred embodiment of the present invention, the clean second periodic structure data is a function of the second component and the second pitch. Alternatively, according to a preferred embodiment of the present invention, the clean second periodic structure data is a function of the second component, the second pitch and a harmonic of the second pitch.

[0017] According to a preferred embodiment of the present invention, the clean third periodic structure data is a function of the third component and the third spacing. Alternatively, according to a preferred embodiment of the present invention, the clean third periodic structure data is a function of the third component, the third spacing and the harmonics of the third spacing.

[0018] Preferably, analyzing the first component, the second component and the third component to thereby determine the offset between the first layer and the second layer includes: identifying a first reference position at which at least one of the maximum and minimum values ​​of the clean first periodic structure data intersects with at least one of the maximum and minimum values ​​of the clean second periodic structure data; identifying a second reference position at at least one of the maximum and minimum values ​​of the clean third periodic structure data, the second reference position most closely intersecting with the first reference position; and calculating the difference between the first reference position and the second reference position to thereby determine the offset between the first layer and the second layer.

[0019] According to a preferred embodiment of the present invention, the second layer also includes: a fourth periodic structure, the fourth periodic structure having a fourth spacing along a fourth axis, the fourth axis is not parallel to the first axis, the second axis or the third axis, a fourth component attributed to the fourth periodic structure is extracted from the aggregate signal, clean fourth periodic structure data is generated from the fourth component, and the determination of the offset between the first layer and the second layer includes: identifying a first reference position at which at least one of the maximum and minimum values ​​of the clean first periodic structure data intersects with at least one of the maximum and minimum values ​​of the clean second periodic structure data; identifying a second reference position at which at least one of the maximum and minimum values ​​of the clean third periodic structure data intersects with at least one of the maximum and minimum values ​​of the clean fourth periodic structure data, the second reference position intersecting most closely with the first reference position; and calculating the difference between the first reference position and the second reference position, thereby determining the offset between the first layer and the second layer.

[0020] According to a preferred embodiment of the present invention, each of the first spacing, the second spacing and the third spacing is between 1 / 1000 and 1 / 4 of the length of the field of view of the wafer imaging tool. Alternatively, according to a preferred embodiment of the present invention, each of the first spacing, the second spacing and the third spacing is between 1 / 500 and 1 / 20 of the length of the field of view of the wafer imaging tool.

[0021] According to a preferred embodiment of the present invention, the multilayer semiconductor device also includes at least a third layer, which is formed together with at least a third layer periodic structure having a third layer spacing along a third layer axis, the third layer axis is not parallel to the first axis, the third layer axis is not parallel to the second axis, and the third layer axis is not parallel to the third axis, and wherein the method includes: generating a single image of the third layer periodic structure, the first periodic structure, and the second periodic structure, thereby providing an aggregate signal; extracting a third layer component from the aggregate signal, the third layer component being attributed to the third layer periodic structure; and analyzing the third layer component, the first component, and the second component, thereby determining the offset between the third layer and the first layer.

[0022] According to another preferred embodiment of the present invention, there is also provided an offset metrology system for measuring offsets in the manufacture of a multilayer semiconductor device, wherein the multilayer semiconductor device comprises: a first periodic structure having a first spacing along a first axis, wherein the first periodic structure is formed together with a first layer of the multilayer semiconductor device; a second periodic structure having a second spacing along a second axis, wherein the second axis is not parallel to the first axis, wherein the second periodic structure is formed together with the first layer of the multilayer semiconductor device; and a third periodic structure having a third spacing along a third axis, wherein the third axis is not parallel to the first axis and the third axis is not parallel to the second axis, wherein the third periodic structure is formed together with the second layer of the multilayer semiconductor device, wherein the third periodic structure The three periodic structures and the first periodic structure and the second periodic structure overlap each other, and the offset metrology system includes: a wafer imaging tool, which is operable to generate a single image of the first periodic structure, the second periodic structure and the third periodic structure, thereby providing an aggregate signal; and an offset analyzer, which is operable to: extract a first component from the aggregate signal, the first component being attributed to the first periodic structure; extract a second component from the aggregate signal, the second component being attributed to the second periodic structure; extract a third component from the aggregate signal, the third component being attributed to the third periodic structure; and analyze the first component, the second component and the third component to determine the offset between the first layer and the second layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will be more fully understood and appreciated from the following detailed description in conjunction with the accompanying drawings, in which:

[0024] Figure 1 is a simplified schematic illustration of a periodic semiconductor device shift metrology system (PSDMMS);

[0025] Figure 2A , 2B and 2C is to use the Figure 1 A simplified pictorial illustration of an embodiment of a multi-layer semiconductor device fabricated by a PSDMMS fabrication system;

[0026] Figure 3A , 3B and 3C is the use of Figure 1 A simplified pictorial illustration of another embodiment of a multilayer semiconductor device fabricated by a PSDMMS fabrication system;

[0027] Figure 4A and 4B Together for illustration can be combined Figure 1 A simplified flow chart of the periodic semiconductor device shift metrology method (PSDMMM) used by the PSDMMS;

[0028] Figure 5 It is useful for understanding Figure 4A and 4B a simplified diagrammatic illustration of a portion of the PSDMMM; and

[0029] Fig. 6A and 6B It is useful for understanding Figures 4A to 5 Simplified pictorial illustration of two embodiments of a portion of a PSDMMM. DETAILED DESCRIPTION

[0030] It should be understood that the following references Figures 1 to 6B The described systems and methods form part of a process for manufacturing a semiconductor device and are described hereinafter with reference to Figures 1 to 6B The described systems and methods measure offsets for use in adjusting the fabrication process of a semiconductor device to more closely align the various layers of the fabricated semiconductor device.

[0031] Reference now Figure 1 and Figures 2A to 2C , Figure 1 is a simplified schematic illustration of a periodic semiconductor device deviation metrology system (PSDMMS) 100, Figures 2A to 2C is a simplified pictorial illustration of an embodiment of a multi-layered semiconductor device 102 fabricated using a fabrication system including the PSDMMS 100 .

[0032] As in Figure 1As seen in FIG. 1 , the PSDMMS 100 includes a wafer imaging tool 110 and an offset data analyzer 120. In a preferred embodiment of the present invention, the wafer imaging tool 110 is a scanning electron microscope. A typical scanning electron microscope that can be used as the wafer imaging tool 110 is the eDR7380 commercially available from KLA Corporation of Milpitas, California, USA. TM . As referenced below Figures 4A to 6B As described, a wafer imaging tool 110, together with an offset data analyzer 120, is operable to measure offsets between layers formed on a wafer 130, the layers being portions of at least one multilayer semiconductor device 102 formed thereon. The wafer imaging tool 110 is characterized by a field of view (FOV) having a characteristic length, typically between 0.1 μm and 20 μm, and more preferably between 0.25 μm and 10 μm.

[0033] As especially in Figures 2A to 2C As seen in FIG. 1 , the multilayer semiconductor device 102 includes at least a first periodic structure 142 formed with a first layer 144 and characterized by a first pitch P along a first axis 146. Figure 2A and 2B In the embodiment of the invention described in , the first layer 144 also includes a second periodic structure 148, the second periodic structure 148 is characterized by a second pitch Q along a second axis 149. A particular feature of the invention is that the first axis 146 and the second axis 149 are not parallel to each other. The multilayer semiconductor device 102 further includes at least a third periodic structure 152, the third periodic structure 152 being formed with the second layer 154 and characterized by a third pitch R along a third axis 156. A particular feature of the invention is that the third axis 156 is not parallel to the first axis 146 or the second axis 149. The third periodic structure 152 at least partially covers or underlies the first and second periodic structures 142 and 148. It should be understood that although Figure 2A The third periodic structure 152 is shown covering the first periodic structure 142 and the second periodic structure 148, but in alternative embodiments, the first periodic structure 142 and the second periodic structure 148 may cover the third periodic structure 152. The first and second layers 144 and 154 may be adjacent layers, but need not be.

[0034] As mentioned above, a particular feature of the present invention is that none of the first axis 146, the second axis 149, or the third axis 156 are parallel to each other. Additionally, one or both of the first and second layers 144 and 154 may include additional periodic features (not shown) having a pitch along yet another axis (not shown).

[0035] In a preferred embodiment of the present invention, the pitches P, Q and R are all different from each other. In an alternative embodiment of the present invention, any or all of the pitches P, Q and R may have the same value. Preferably, each of the first periodic structure 142, the second periodic structure 148 and the third periodic structure 152 has an area at least as large as the FOV of the wafer imaging tool 110. Preferably, each of the pitches P, Q and R is between 1 / 1000 and 1 / 4 of the length of the FOV of the wafer imaging tool 110. More preferably, each of the pitches P, Q and R is between 1 / 500 and 1 / 20 of the length of the FOV of the wafer imaging tool 110. Therefore, each of the pitches P, Q and R is preferably between 1 nm and 2500 nm, and more preferably between 2 nm and 500 nm.

[0036] As in Figures 3A to 3C As seen in FIG. 1 , in another preferred embodiment of the present invention, the multilayer semiconductor device 102 includes at least a first periodic structure 142 formed with a first layer 144 and characterized by a first pitch P along a first axis 146. Figure 3A and 3B In the embodiment of the invention described in , the first layer 144 further comprises a second periodic structure 148 characterized by a pitch Q along a second axis 149. A particular feature of the invention is that the first axis 146 and the second axis 149 are not parallel to each other.

[0037] exist Figures 3A to 3C In the embodiment shown in , the multilayer semiconductor device 102 further includes at least a third periodic structure 152 formed with a second layer 154 and characterized by a third pitch R along a third axis 156. Figure 3A and 3C In the embodiment of the invention described in , the second layer 154 further includes a fourth periodic structure 158 characterized by a spacing S along a fourth axis 159. A particular feature of the invention is that the axes 146, 149, 156, and 159 are not parallel to each other. The third periodic structure 152 and the fourth periodic structure 158 at least partially cover or underlie the first periodic structure 142 and the second periodic structure 148. It should be understood that although Figure 3A The third and fourth periodic structures 152, 158 are shown covering the first and second periodic structures 142, 148, but in alternative embodiments, the first and second periodic structures 142, 148 may cover the third and fourth periodic structures 152, 158. The first and second layers 144, 154 may be adjacent layers, but need not be.

[0038] As mentioned above, a particular feature of the present invention is that none of the first axis 146, the second axis 149, the third axis 156, and the fourth axis 159 are parallel to each other. In addition, one or both of the first layer 144 and the second layer 154 may include additional periodic features (not shown) having a pitch along yet another axis (not shown).

[0039] In a preferred embodiment of the present invention, the pitches P, Q, R and S are all different from each other. In an alternative embodiment of the present invention, any or all of the pitches P, Q, R and S may have the same value. Preferably, each of the first periodic structure 142, the second periodic structure 148, the third periodic structure 152 and the fourth periodic structure 158 has an area at least as large as the FOV of the wafer imaging tool 110. Preferably, each of the pitches P, Q, R and S is between 1 / 1000 and 1 / 4 of the length of the FOV of the wafer imaging tool 110. More preferably, each of the pitches P, Q, R and S is between 1 / 500 and 1 / 20 of the length of the FOV of the wafer imaging tool 110. Therefore, each of the pitches P, Q, R and S is preferably between 1 nm and 2500 nm, and more preferably between 2 nm and 500 nm.

[0040] It should be understood that the above reference Figures 1 to 3C The multilayer semiconductor device 102 described may also include three or more layers, and the following reference Figures 4A to 6B The method described measures the offset between them. In the case where the multilayer semiconductor device 102 includes three or more layers for offset measurement, each layer for offset measurement includes at least one periodic structure, and at least one of the layers for offset measurement includes at least two periodic structures. Each periodic structure is formed with a corresponding layer of the semiconductor device wafer whose offset is to be measured, and is characterized by a spacing along the axis. In a preferred embodiment of the present invention, the axes of any two periodic structures formed to have a layer between which the offset is to be measured are not parallel axes. It should be noted that each periodic structure preferably has an area at least as large as the FOV of the wafer imaging tool 110. It should be further noted that each periodic structure preferably has at least one spacing between 1 / 1000 and 1 / 4 of the length of the FOV of the wafer imaging tool 110 and more preferably between 1 / 500 and 1 / 20 of the length of the FOV of the wafer imaging tool 110. Therefore, each periodic structure preferably has at least one spacing between 1nm and 2500nm and more preferably between 2nm and 500nm. It should be understood that the offset of any two layers of such a multilayer semiconductor device 102 can be measured by the system 100 by comparing the offset of the periodic structures on the two layers, as described below with reference to Figures 4A to 6B describe.

[0041] Reference now Figure 4A and 4B and Figure 5 , Figure 4A and 4B Together are simplified flow charts illustrating a periodic semiconductor device shift metrology method (PSDMMM) 200 that may be used by PSDMMS 100, Figure 5 is a simplified pictorial illustration of a portion of PSDMMM 200 .

[0042] As in Figure 4A As seen in FIG. 4 , in a first step 202, a wafer including at least one multilayer semiconductor device 102 formed thereon is provided. The wafer imaging tool 110 images the wafer, thereby generating a single image, thereby providing an aggregate signal 204. The aggregate signal 204 includes components due to each of the first periodic structure 142, the second periodic structure 148, and the third periodic structure 152. It should be appreciated that the aggregate signal 204 illustrated in FIG. 4 shows a simplified representation of grayscale contrast positions for an image of the semiconductor device 102 taken using the wafer imaging tool 110. In a preferred embodiment of the present invention, the aggregate signal 204 includes contributions from the entire area of ​​the FOV of the wafer imaging tool 110.

[0043] As in Figure 4A and 5 As seen in FIG. 1 , at the next step 212, the offset data analyzer 120 extracts raw data 214 attributable to the first periodic structure 142 from the aggregate signal 204 generated at step 202. It should be appreciated that the raw data 214 is extracted from the aggregate signal 204 by considering only the components of the aggregate signal 204 that are located along the axis 146.

[0044] At the next step 222, the offset data analyzer 120 cleans the raw data 214, thereby generating clean first periodic structure data 224. The clean first periodic structure data 224 preferably comprises a linear combination of a set of periodic functions (e.g., sinusoidal functions, preferably one periodic function for each harmonic considered) and deviations. The periodic function of each harmonic contains information related to the pitch P as well as weighting factors and phase shifts. The deviations, weighting factors and phase shifts are preferably fitted to the raw data 214 using a least squares error minimization method.

[0045] In a preferred embodiment of the present invention, the clean first periodic structure data 224 is expressed by Equation 1:

[0046]

[0047] Where f1(x) is the clean first periodic structure data 224, c1 is the deviation, k is the index indicating the harmonic under consideration, n1 is the total number of harmonics under consideration, and a 1,kis the weighting factor, P1 is the spacing P, x is the linear position in the profile and For phase shift.

[0048] Since the pitch P along the axis 146 of the first periodic structure 142 is known, the offset data analyzer 120 generates clean first periodic structure data 224 by removing components that do not correspond to the periodicity of the pitch P or at least one of the pitch P and its higher harmonics from the raw data 214. Such components may, for example, be attributable to other features of the multilayer semiconductor device 102 that are located completely or partially along the axis 146.

[0049] At the next step 232, the offset data analyzer 120 extracts raw data attributed to the second periodic structure 148 from the aggregate signal 204 generated at step 202. It will be appreciated that the raw data attributed to the second periodic structure 148 is extracted from the aggregate signal 204 by considering only components of the aggregate signal 204 located along the axis 149.

[0050] At the next step 242, the offset data analyzer 120 cleans the raw data attributed to the second periodic structure 148, thereby generating clean second periodic structure data. The clean second periodic structure data preferably comprises a linear combination of a set of periodic functions (e.g., sinusoidal functions, preferably one periodic function for each harmonic considered) and deviations. The periodic function of each harmonic comprises information related to the spacing Q as well as weighting factors and phase shifts. The deviations, weighting factors and phase shifts are preferably fitted to the raw data attributed to the second periodic structure 148 using a least squares error minimization method.

[0051] In a preferred embodiment of the present invention, the clean second periodic structure data is expressed by Equation 2:

[0052]

[0053] Where f2(x) is the clean second periodic structure data, c2 is the deviation, k is the index indicating the harmonic under consideration, n2 is the total number of harmonics under consideration, and a 2,k is a weighting factor, P2 is the spacing Q of the second periodic structure 148, x is the linear position in the cross section and For phase shift.

[0054] Since the pitch Q along the axis 149 of the second periodic structure 148 is known, the offset data analyzer 120 generates clean second periodic structure data by removing components that do not correspond to the periodicity of the pitch Q or at least one of the pitch Q and its higher harmonics from the raw data attributed to the second periodic structure. Such components may, for example, be attributed to other features of the multilayer semiconductor device 102 that are located completely or partially along the axis 149.

[0055] At the next step 252, the offset data analyzer 120 extracts raw data attributed to the third periodic structure 152 from the aggregate signal 204 generated at step 202. It should be appreciated that the raw data attributed to the third periodic structure 152 is extracted from the aggregate signal 204 by considering only components of the aggregate signal 204 located along the axis 156.

[0056] At the next step 262, the offset data analyzer 120 cleans the raw data generated at step 252, thereby generating clean third periodic structure data corresponding to the raw data generated at step 252. The clean second periodic structure data corresponding to the raw data generated at step 252 preferably includes a linear combination of a set of periodic functions (e.g., sinusoidal functions, preferably one periodic function for each harmonic considered) and deviations. The periodic function of each harmonic contains information related to the spacing R as well as weighting factors and phase shifts. The deviations, weighting factors and phase shifts are preferably fitted to the raw data generated at step 252 using a least squares error minimization method.

[0057] In a preferred embodiment of the present invention, the clean third periodic structure data corresponding to the original data generated at step 252 is expressed by Equation 3:

[0058]

[0059] Where f3(x) is the clean third periodic structure data corresponding to the original data generated in step 252, c3 is the deviation, k is the index indicating the harmonic under consideration, n3 is the total number of harmonics under consideration, and a 3,k is the weighting factor, P3 is the spacing R, x is the linear position in the profile and For phase shift.

[0060] Since the pitch R along the axis 156 of the third periodic structure 152 is known, the offset data analyzer 120 generates clean second periodic structure data corresponding to the raw data generated at step 252 by removing components that do not correspond to the periodicity of the pitch R or at least one of the pitch R and its higher harmonics from the raw data generated at step 252. Such components may, for example, be attributable to other features of the multilayer semiconductor device 102 that are located completely or partially along the axis 156.

[0061] At the next step 272, a determination is made as to whether to extract additional data attributable to one or more additional periodic structures formed with either layer 144 or 154 from the aggregate signal 204 generated at step 202. If additional data attributable to one or more additional periodic structures formed with either layer 144 or 154 is to be extracted, then at the next step 282, the offset data analyzer 120 proceeds to extract additional raw data from the aggregate signal 204 by considering only components of the aggregate signal 204 that are located along the axis along which the additional periodic structure currently under consideration exhibits periodicity.

[0062] Also at step 282, the offset data analyzer 120 cleans the additional raw data extracted at step 282, thereby generating additional clean periodic structure data. The additional clean periodic structure data preferably comprises a linear combination of a set of periodic functions (e.g., sinusoidal functions, preferably one periodic function for each harmonic considered) and deviations. The periodic function for each harmonic contains information related to the spacing of the additional periodic structure currently being considered as well as weighting factors and phase shifts. The deviations, weighting factors and phase shifts are preferably fitted to the additional raw data generated at step 282 using a least squares error minimization method.

[0063] In a preferred embodiment of the present invention, the additional clean periodic structure data is expressed by Equation 4:

[0064]

[0065] Where f4(x) is the additional clean periodic structure data, c4 is the deviation, k is the index indicating the harmonic considered, n4 is the total number of harmonics considered, and a 4,k is the weighting factor, P4 is the spacing of the additional periodic structure currently considered, x is the linear position in the profile and For phase shift.

[0066] Since the pitch P4 of the additional periodic structure currently under consideration is known, the offset data analyzer 120 generates additional clean second periodic structure data by removing components that do not correspond to the periodicity of the pitch of the additional periodic structure currently under consideration or at least one of the pitch of the additional periodic structure currently under consideration and its higher harmonics from the additional raw data generated at step 282. Such components may, for example, be attributable to other features of the multilayer semiconductor device 102 that are located completely or partially along the axis along which the additional periodic structure currently under consideration exhibits periodicity.

[0067] Following step 282, the PSDMMM 200 returns to step 272 and determines whether to extract additional data due to another periodic structure formed with either layer 144 or 154 from the aggregate signal 204 generated at step 202. If additional data due to another periodic structure is not to be extracted, then at the next step 292, the offset between the layers 144 and 154 of the multilayer semiconductor device 102 is calculated, as described below with reference to Fig. 6A and 6B describe.

[0068] Reference Fig. 6A and 6B , which is a simplified pictorial illustration of different embodiments of step 292 of PSDMMM 200 .

[0069] As in Fig. 6A As seen in FIG. 29 , when the first layer 144 includes the first periodic structure 142 and the second periodic structure 148, and the second layer 154 includes the third periodic structure 152, at step 292, the offset data analyzer 120 identifies a first reference position 314 at the intersection of a maximum value or a minimum value (shown by element symbol 318) of the clean first periodic structure data 224 generated at step 222 and a maximum value or a minimum value (shown by element symbol 320) of the clean second periodic structure data generated at step 242. Also at step 292, the offset data analyzer 120 identifies a second reference position 334 at a maximum value or a minimum value (shown by element symbol 338) of the clean third periodic structure data generated at step 262, which second reference position 334 intersects the first reference position 314 most closely. Next, the offset data analyzer 120 calculates a distance 340 between the first reference location 314 and the second reference location 334 , and reports the distance 340 as an offset in one dimension between the first layer 144 and the second layer 154 of the multilayer semiconductor device 102 .

[0070] As in Figure 6BAs seen in FIG. 29 , when the first layer 144 includes the first periodic structure 142 and the second periodic structure 148, and the second layer 154 includes the third periodic structure 152 and the fourth periodic structure 158, at step 292, the offset data analyzer 120 identifies a first reference position 354 at the intersection of the maximum value or minimum value (shown by element symbol 358) of the clean first periodic structure data 224 generated at step 222 and the maximum value or minimum value (shown by element symbol 360) of the clean second periodic structure data generated at step 242. Also at step 292, the offset data analyzer 120 identifies a second reference position 374 at the intersection of the maximum value or minimum value (shown by element symbol 376) of the clean third periodic structure data generated at step 262 and the maximum value or minimum value (shown by element symbol 378) of the additional clean periodic structure data generated at step 282, which is closest to the first reference position 354. Next, the offset data analyzer 120 calculates a distance 380 between the first reference location 354 and the second reference location 374 , and reports the distance 380 as an offset in two dimensions between the first layer 144 and the second layer 154 of the multilayer semiconductor device 102 .

[0071] Similarly, when at least one of the first layer 144 and the second layer 154 includes at least three periodic structures, at step 292, the offset data analyzer 120 identifies a first reference position at an intersection where the maximum or minimum values ​​of all clean periodic structure data attributed to the periodic structures on the first layer 144 intersect. Also at step 292, the offset data analyzer 120 identifies a second reference position closest to the first reference position at an intersection where the maximum or minimum values ​​of all clean periodic structure data attributed to the periodic structures on the second layer 154 intersect. Next, the offset data analyzer 120 calculates the distance between the first reference position and the second reference position, and reports the distance as an offset in two dimensions between the first layer 144 and the second layer 154 of the multilayer semiconductor device 102.

[0072] In one embodiment of the present invention, the modification as described above with reference to Figures 4A to 6BThe PSDMMM 200 described is used to measure the offset between the third layer of the multilayer semiconductor device 102 and at least one of the first layer 144 and the second layer 154. In this embodiment, the PSDMMM 200 generates a single image of at least one periodic structure formed with the third layer together with at least one of the first periodic structure 142, the second periodic structure 148, and the third periodic structure 152, thereby providing an aggregate signal. The PSDMMM 200 also extracts and cleans the component from the aggregate signal attributed to the periodic structure formed with the third layer, and the generated clean data corresponds to the periodic structure formed with the third layer and at least one of the first periodic structure 142, the second periodic structure 148, and the third periodic structure 152 to determine the offset between the third layer and at least one of the first layer 144 and the second layer 154.

[0073] It will be appreciated by those skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. The scope of the present invention includes both combinations and sub-combinations of the various features described above, as well as modifications thereof, all of which are not in the prior art.

Claims

1. A method of offset metrology for measuring offset in the manufacture of a multilayer semiconductor device, the multilayer semiconductor device comprising: a first periodic structure having a first pitch along a first axis, the first periodic structure being formed together with a first layer of the multilayer semiconductor device; a second periodic structure having a second pitch along a second axis, the second axis being non-parallel to the first axis, the second periodic structure being formed together with the first layer of the multilayer semiconductor device; and a third periodic structure having a third pitch along a third axis, the third axis being non-parallel to the first axis and the third axis being non-parallel to the second axis, the third periodic structure being formed together with a second layer of the multilayer semiconductor device, the third periodic structure and the first periodic structure and the second periodic structure overlapping each other; The offset metrology method includes: generating a single image of the first periodic structure, the second periodic structure, and the third periodic structure, thereby providing an aggregate signal; extracting a first component from the aggregate signal, the first component being attributable to the first periodic structure; extracting a second component from the aggregate signal, the second component being attributable to the second periodic structure; extracting a third component from the aggregate signal, the third component being attributable to the third periodic structure; and The first component, the second component, and the third component are analyzed to thereby determine an offset between the first layer and the second layer.

2. The offset metrology method according to claim 1, further comprising: Producing clean first periodic structure data; Generate clean second periodic structure data; and Generate clean third periodic structure data.

3. The offset metrology method according to claim 2, wherein the clean first periodic structure data is: a function of the first component and the first spacing; or A function of the first component, the first pitch, and harmonics of the first pitch.

4. The offset metrology method according to claim 2, wherein the clean second periodic structure data is: a function of the second component and the second spacing; or A function of the second component, the second pitch, and harmonics of the second pitch.

5. The offset metrology method according to claim 2, wherein the clean third periodic structure data is: a function of the third component and the third spacing; or A function of the third component, the third pitch, and harmonics of the third pitch.

6. The method of offset metrology according to claim 2, wherein analyzing the first component, the second component, and the third component to thereby determine the offset between the first layer and the second layer comprises: identifying a first reference position where at least one of a maximum value and a minimum value of the clean first periodic structure data intersects at least one of a maximum value and a minimum value of the clean second periodic structure data; identifying a second reference position at at least one of a maximum value and a minimum value of the clean third periodic structure data, the second reference position most closely intersecting the first reference position; and A difference between the first reference position and the second reference position is calculated, thereby determining an offset between the first layer and the second layer.

7. The offset metrology method according to claim 1, wherein: The second layer further includes a fourth periodic structure having a fourth pitch along a fourth axis, the fourth axis being non-parallel to the first axis, the second axis, or the third axis; extracting a fourth component attributable to the fourth periodic structure from the aggregate signal; generating clean fourth periodic structure data from the fourth component; and The determining of an offset between the first layer and the second layer comprises: identifying a first reference position where at least one of a maximum value and a minimum value of the clean first periodic structure data intersects at least one of a maximum value and a minimum value of the clean second periodic structure data; identifying a second reference position where at least one of a maximum value and a minimum value of the clean third periodic structure data intersects with at least one of a maximum value and a minimum value of the clean fourth periodic structure data, the second reference position most closely intersecting with the first reference position; and A difference between the first reference position and the second reference position is calculated, thereby determining an offset between the first layer and the second layer.

8. The offset metrology method of claim 1, and wherein the multilayer semiconductor device further comprises at least a third layer formed with at least a third layer periodic structure having a third interlayer spacing along a third layer axis, the third layer axis being non-parallel to the first axis, the third layer axis being non-parallel to the second axis and the third layer axis being non-parallel to the third axis, and wherein the method comprises: generating a single image of the third layer periodic structure and the first periodic structure and the second periodic structure, thereby providing an aggregate signal; extracting a third layer component from the aggregate signal, the third layer component being attributed to the third layer periodic structure; and The third layer component, the first component and the second component are analyzed to thereby determine an offset between the third layer and the first layer.

9. An offset metrology system for measuring offset in the manufacture of a multilayer semiconductor device, the multilayer semiconductor device comprising: a first periodic structure having a first pitch along a first axis, the first periodic structure being formed with a first layer of the multilayer semiconductor device; a second periodic structure having a second pitch along a second axis, the second axis being non-parallel to the first axis, the second periodic structure being formed with the first layer of the multilayer semiconductor device; and a third periodic structure having a third pitch along a third axis, the third axis being non-parallel to the first axis and the third axis being non-parallel to the second axis, the third periodic structure being formed with a second layer of the multilayer semiconductor device, the third periodic structure and the first periodic structure and the second periodic structure overlying each other; The offset metrology system comprises: a wafer imaging tool operable to produce a single image of the first periodic structure, the second periodic structure and the third periodic structure, thereby providing an aggregate signal; and An excursion analyzer operable to: extracting a first component from the aggregate signal, the first component being attributable to the first periodic structure; extracting a second component from the aggregate signal, the second component being attributable to the second periodic structure; extracting a third component from the aggregate signal, the third component being attributable to the third periodic structure; and The first component, the second component, and the third component are analyzed to thereby determine an offset between the first layer and the second layer.

10. The excursion metrology system of claim 9, wherein the excursion analyzer is further operable to: Producing clean first periodic structure data; generating clean second periodic structure data; and Generate clean third periodic structure data.

11. The offset metrology system of claim 10, wherein the clean first periodic structure data is: a function of the first component and the first spacing; or A function of the first component, the first pitch, and harmonics of the first pitch.

12. The offset metrology system of claim 10, wherein the clean second periodic structure data is: a function of the second component and the second spacing; or A function of the second component, the second pitch, and harmonics of the second pitch.

13. The offset metrology system of claim 10, wherein the clean third periodic structure data is: a function of the third component and the third spacing; or A function of the third component, the third pitch, and harmonics of the third pitch.

14. The offset metrology system of claim 10, wherein analyzing the first component, the second component, and the third component to thereby determine the offset between the first layer and the second layer comprises: identifying a first reference position where at least one of a maximum value and a minimum value of the clean first periodic structure data intersects at least one of a maximum value and a minimum value of the clean second periodic structure data; identifying a second reference position at at least one of a maximum value and a minimum value of the clean third periodic structure data, the second reference position most closely intersecting the first reference position; and A difference between the first reference position and the second reference position is calculated, thereby determining an offset between the first layer and the second layer.

15. The excursion metrology system of claim 9, and wherein: The second layer further includes a fourth periodic structure having a fourth pitch along a fourth axis, the fourth axis being non-parallel to the first axis, the second axis, or the third axis; extracting a fourth component attributable to the fourth periodic structure from the aggregate signal; generating clean fourth periodic structure data from the fourth component; and The determining of an offset between the first layer and the second layer comprises: identifying a first reference position where at least one of a maximum value and a minimum value of the clean first periodic structure data intersects at least one of a maximum value and a minimum value of the clean second periodic structure data; identifying a second reference position where at least one of a maximum value and a minimum value of the clean third periodic structure data intersects with at least one of a maximum value and a minimum value of the clean fourth periodic structure data, the second reference position most closely intersecting with the first reference position; and A difference between the first reference position and the second reference position is calculated, thereby determining an offset between the first layer and the second layer.

16. The offset metrology system of claim 9, and wherein the first pitch, the second pitch, and the third pitch are each between 1 / 1000 and 1 / 4 of a length of a field of view of the wafer imaging tool.

17. The offset metrology system of claim 9, and wherein the first pitch, the second pitch, and the third pitch are each between 1 / 500 and 1 / 20 of a length of a field of view of the wafer imaging tool.

18. The offset metrology system of claim 9, and wherein the multilayer semiconductor device further comprises at least a third layer formed with at least a third layer periodic structure having a third interlayer spacing along a third layer axis, the third layer axis being non-parallel to the first axis, the third layer axis being non-parallel to the second axis and the third layer axis being non-parallel to the third axis, and wherein the wafer imaging tool is further operable to: generating a single image of the third layer periodic structure and the first periodic structure and the second periodic structure, thereby providing an aggregate signal; and wherein the shift analyzer is further operable to: extracting a third layer component from the aggregate signal, the third layer component being attributed to the third layer periodic structure; and The third layer component, the first component and the second component are analyzed to thereby determine an offset between the third layer and the first layer.

Images