Method for optimizing measurement precision of registration error
By adding auxiliary patterns and filling them with copper in the blank area in front of the photolithographic measurement mark, the problem of the photolithographic measurement mark signal being affected by the previous layer process was solved, and the measurement accuracy of the registration error was improved.
Patent Information
- Application Number
- CN202511578608.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-31
- Publication Date
- 2026-02-06
AI Technical Summary
In existing technologies, the photolithographic measurement marking signal is easily affected by the previous layer process, resulting in unstable registration error and affecting measurement accuracy.
Add auxiliary graphics, such as windmill-shaped graphics, to the blank areas of the front layer of the photolithography measurement mark, and fill the gaps with metallic copper to increase the reflectivity of the front layer of the photolithography measurement mark.
By adding auxiliary patterns and copper filler, the influence of noise is reduced, the emission signal of the photolithographic measurement mark is enhanced, and the measurement accuracy of the registration error is optimized.
Smart Images
Figure CN121477553A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor technology, and specifically to a method for optimizing the measurement accuracy of registration error. Background Technology
[0002] Advanced semiconductor manufacturing processes impose two limiting parameters on photolithography: critical dimension (CD) and overlay error. Overlay error refers to the relative position between the current pattern and the reference pattern. It measures the alignment quality, directly quantifying the positional deviation between the current layer and the reference layer. As the critical dimension shrinks, the requirements for overlay error become increasingly stringent. The pattern remaining in the photoresist after exposure and development must be aligned with the existing pattern on the wafer substrate to prevent short circuits and open circuits in the devices.
[0003] As advanced technologies demand higher precision and processes become more complex, the OVLMark signal is susceptible to the influence of the preceding process. Furthermore, the instability of the OVLMark signal introduces overlay errors. Therefore, a stable OVLMark signal is particularly important for measurement. Summary of the Invention
[0004] In view of the shortcomings of the prior art described above, the purpose of this application is to provide a method for optimizing the measurement accuracy of overlay error, which solves the problem of unstable photolithographic measurement marking signal caused by the influence of previous layer processes in the prior art.
[0005] To achieve the above and other related objectives, this application provides a method for optimizing the measurement accuracy of registration error, comprising:
[0006] Step 1: Simultaneously form the front layer pattern of photolithographic measurement markings and the auxiliary pattern in the blank area between the front layer patterns on the wafer;
[0007] Step 2: Fill the gap between the front layer pattern and the auxiliary pattern of the photolithographic measurement mark with metallic copper;
[0008] Step 3: Form the current layer pattern of photolithographic measurement markings on the wafer;
[0009] Step four: Measure the complete photolithographic measurement mark prepared through the above steps to obtain the registration error information.
[0010] Preferably, the auxiliary pattern is perpendicular to the front layer pattern of the photolithographic measurement mark.
[0011] Preferably, the auxiliary graphic includes a windmill-shaped logo.
[0012] Preferably, the types and quantities of the current layer pattern and the previous layer pattern of the photolithographic measurement mark are the same.
[0013] Preferably, in step one, a photoresist layer with a pattern of a front layer pattern and an auxiliary pattern of photolithographic measurement marks is first formed on the wafer by first photolithography. Then, using the photoresist layer as a mask, the front layer pattern of the photolithographic measurement marks and the auxiliary pattern located in the blank area between the front layer patterns are simultaneously formed on the wafer by first etching. The front layer pattern of the photolithographic measurement marks formed on the wafer serves as the front layer of the photolithographic measurement marks.
[0014] Preferably, in step two, a copper metal layer is first formed on the wafer using a copper electroplating process to fill the gap between the front layer pattern and the auxiliary pattern of the photolithographic measurement mark, and then the copper metal outside the gap is removed using a chemical mechanical polishing process.
[0015] Preferably, in step three, a photoresist layer with a photolithographic measurement mark pattern is formed on the wafer by a second photolithography process as the photolithographic measurement mark layer.
[0016] As described above, the method for optimizing the measurement accuracy of overlay error provided in this application has the following beneficial effects: by adding auxiliary patterns to the blank area of the front layer of the photolithographic measurement mark to change the reflectivity of the front layer of the photolithographic measurement mark, the emission signal of the photolithographic measurement mark is increased, thereby optimizing the measurement accuracy of overlay error. Attached Figure Description
[0017] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0018] Figure 1 This is a schematic diagram showing the addition of auxiliary graphics to the blank area in front of the photolithographic measurement mark in the method for optimizing the measurement accuracy of overlay error provided in the embodiments of this application;
[0019] Figure 2 The flowchart shown is a method for optimizing the measurement accuracy of registration error according to an embodiment of this application. Detailed Implementation
[0020] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this invention.
[0021] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0022] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," indicating orientation or positional relationships, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.
[0023] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.
[0024] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.
[0025] The advanced node lithography process measures the lithographic measurement mark using a diffraction-based measurement technique called DBO. By analyzing the changes in light intensity distribution after diffraction of two layers (the front layer and the current layer of the lithographic measurement mark), the interlayer offset is revealed.
[0026] Photolithographic measurement marks are typically fixed in place on the dicing track, and the front layer pattern of the photolithographic measurement mark exists as follows: Figure 1 As the complexity of the process increases, the blank area shown is affected by the previous layer process of photolithography measurement marking. This blank area causes the reflected light to be messy, and the introduction of divergent light leads to left-right asymmetry, which can cause deviations in overlay measurement.
[0027] To address this problem, this application provides a method for optimizing the measurement accuracy of registration error. For example... Figure 1 As shown, an auxiliary graphic is added to the blank area in front of the photolithography measurement mark. In order to reduce the influence of noise, the auxiliary graphic is preferably perpendicular to the front graphic of the photolithography measurement mark, such as a windmill-shaped mark (AIM).
[0028] To increase the reflectivity of the front layer of the photolithographic measurement mark, metallic copper is used to fill the gap between the front layer pattern and the auxiliary pattern of the photolithographic measurement mark.
[0029] like Figure 2 As shown, the method for optimizing the measurement accuracy of registration error includes the following steps:
[0030] Step 1: Simultaneously form the front layer pattern of photolithographic measurement markings and the auxiliary pattern in the blank area between the front layer patterns on the wafer;
[0031] Step 2: Fill the gap between the front layer pattern and the auxiliary pattern of the photolithographic measurement mark with metallic copper;
[0032] Step 3: Form the current layer pattern of photolithographic measurement markings on the wafer;
[0033] Step four: Measure the complete photolithographic measurement mark prepared through the above steps to obtain the registration error information.
[0034] In step one, a photoresist layer with a front layer pattern and an auxiliary pattern of photolithographic measurement marks is first formed on the wafer by the first photolithography. Then, using the photoresist layer as a mask, the front layer pattern of photolithographic measurement marks (as the front layer of photolithographic measurement marks) and the auxiliary pattern located in the blank area between the front layer patterns are simultaneously formed on the wafer by the first etching.
[0035] In step two, a copper metal layer is first formed on the wafer using a copper electroplating process to fill the gap between the front and auxiliary patterns of the photolithographic measurement mark. Then, the copper metal outside the gap is removed using a chemical mechanical polishing process.
[0036] In step three, a photoresist layer with a photolithographic measurement mark is formed on the wafer by the second photolithography as the current layer of the photolithographic measurement mark. The type and number of the current layer pattern of the photolithographic measurement mark are the same as those of the previous layer pattern.
[0037] In step four, the complete photolithographic measurement mark is composed of the front layer of the photolithographic measurement mark formed in step one and the current layer of the photolithographic measurement mark formed in step three, such as... Figure 1 As shown, the auxiliary pattern formed in the blank area of the front layer of the photolithography measurement mark can reduce the noise caused by the process used to form the front layer of the photolithography measurement mark during the measurement process, and increase the transmission signal of the photolithography measurement mark during the measurement.
[0038] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of this application. Therefore, the drawings only show the components related to this invention and are not drawn according to the actual number, shape and size of the components. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.
[0039] In summary, the method for optimizing the measurement accuracy of overlay error provided in this application changes the reflectivity of the front layer of the photolithographic measurement mark by adding auxiliary patterns to the blank area in front of the mark, thereby increasing the emission signal of the mark and thus optimizing the measurement accuracy of overlay error. Therefore, this application effectively overcomes the various shortcomings of the prior art and has high industrial applicability.
[0040] The above embodiments are merely illustrative of the principles and effects of this application and are not intended to limit this application. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this invention should still be covered by the claims of this application.
Claims
1. A method for optimizing the measurement accuracy of registration error, characterized in that, The method includes: Step 1: Simultaneously form a front layer pattern of photolithographic measurement markings and an auxiliary pattern located in the blank area between the front layer patterns on the wafer; Step 2: Fill the gap between the front layer pattern of the photolithographic measurement mark and the auxiliary pattern with metallic copper; Step 3: Form the current layer pattern of photolithographic measurement marks on the wafer; Step four: Measure the complete photolithographic measurement mark prepared through the above steps to obtain the registration error information.
2. The method according to claim 1, characterized in that, The auxiliary graphic is perpendicular to the front layer graphic of the photolithographic measurement mark.
3. The method according to claim 2, characterized in that, The auxiliary graphic includes a windmill-shaped logo.
4. The method according to claim 1, characterized in that, The types and quantities of the current layer pattern and the previous layer pattern of the photolithographic measurement mark are consistent.
5. The method according to claim 1, characterized in that, In step one, a photoresist layer with the front layer pattern of the photolithographic measurement mark and the auxiliary pattern is first formed on the wafer by first photolithography. Then, using the photoresist layer as a mask, the front layer pattern of the photolithographic measurement mark and the auxiliary pattern located in the blank area between the front layer pattern are simultaneously formed on the wafer by first etching. The front layer pattern of the photolithographic measurement mark formed on the wafer serves as the front layer of the photolithographic measurement mark.
6. The method according to claim 1, characterized in that, In step two, a copper metal layer is first formed on the wafer by copper electroplating to fill the gap between the front layer pattern and the auxiliary pattern of the photolithographic measurement mark, and then the copper metal outside the gap is removed by chemical mechanical polishing.
7. The method according to claim 1, characterized in that, In step three, a photoresist layer with the photolithographic measurement mark pattern is formed on the wafer by a second photolithography process, serving as the current layer of the photolithographic measurement mark.