Monitoring patterns for high light transmittance products and methods of use thereof

Abstract

The invention provides a monitoring pattern for a high-light-transmittance product and a using method of the monitoring pattern. The monitoring pattern provided by the invention is characterized in that the shape of the monitoring pattern is a circular hole. The corresponding monitoring method comprises the following steps of: forming a corresponding photoresist pattern on a wafer by using a photoetching mask plate containing the round-hole-shaped monitoring pattern through an additional phase layer-photoetching process; and then etching is carried out based on the photoresist pattern to form a monitoring pattern structure, and critical dimension measurement is carried out on the diameter of the structure. By adopting the round hole-shaped pattern with a more stable structure, the photoresist top loss can be effectively resisted, and the pattern fidelity is ensured, so that stable and reliable key size monitoring is realized, and the monitoring success rate and the product yield are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductor technology, and in particular to a monitoring pattern for high-transmittance products and a method of using the same. BACKGROUND

[0002] In advanced semiconductor manufacturing processes, photolithography is a key step to define the fine patterns of various devices and interconnections in integrated circuits. In order to ensure the stability of photolithography process and the high yield of final products, it is necessary to monitor the critical dimensions (CD) on-line during the production. Such monitoring is usually achieved by setting special monitoring patterns in the scribe lanes or specific test areas of the chips. By measuring the dimensions of these monitoring patterns formed after photolithography or etching, process deviations can be detected in time so as to make adjustments.

[0003] For example, in advanced logic processes at 28 nanometers and below, in order to form ultra-fine patterns on wafers with dimensions much smaller than the wavelength of the exposure light source, it is usually necessary to use resolution enhancement techniques, such as the additional phase layer-photo (APL-Photo) process. APL-Photo is a technique based on phase-shift masks. The core principle is to set phase shifters on specific areas of the mask, so that the light passing through the areas and the light of adjacent areas have a phase difference (usually 180 degrees), and use the destructive interference effect to form dark areas with extremely high contrast at the boundaries of the two areas, thereby greatly improving the definition and resolution of the photolithography patterns. In practice, especially in complex double or multiple patterning schemes, the "additional phase layer" (APL) specifically refers to a specific photolithography step used to define a key core pattern (such as a transistor gate), which cooperates with other modified photolithography steps to complete the final circuit patterning. Since the APL-Photo process aims to form the most critical and finest structures in the circuit, it has a high sensitivity to the topography, dimensional uniformity and contour integrity of the photoresist pattern.

[0004] In order to monitor such high-precision processes, it is conventional to set strip-shaped monitoring patterns, so-called "critical dimension bars" (CD bars), in the test areas of the chips. These critical dimension bars are usually designed in two different environmental layouts, isolated and dense, in order to comprehensively reflect the process conditions.

[0005] However, when the above-mentioned conventional monitoring scheme is applied to a product with high light transmittance characteristics (for example, a product with a light transmittance greater than 90%), a serious technical problem is encountered. In such a product, the area of the photoresist that needs to be exposed and removed (developed) in the photoetching step is very large and relatively concentrated. This large-area developing process is extremely prone to cause the remaining small amount of photoresist used to form the monitoring pattern to have a significant "top loss" phenomenon, that is, the height of the photoresist is reduced, the sidewall profile is tilted, or even completely disappears. Due to the serious degradation of the profile of the photoresist pattern as a subsequent etching mask, the "critical dimension bar" monitoring pattern finally formed on the wafer also has a collapsed profile or a distorted size, so that accurate online monitoring cannot be performed by the measurement equipment.

[0006] Therefore, the prior art has the defect that when the APL-Photo process of a high light transmittance product is monitored, the monitoring pattern fails due to photoresist top loss, and the critical dimension cannot be accurately monitored, which seriously affects the process stability and product yield of advanced nodes. There is an urgent need for a new monitoring pattern design that can resist photoresist top loss in this specific application scenario. SUMMARY

[0007] The present application aims to solve the deficiencies in the prior art. As described in the background, in advanced semiconductor processes (such as additional phase layer-photoetching processes of 28 nanometers and below nodes) for high light transmittance products, the traditional strip-shaped online monitoring pattern, due to the need for large-area removal of photoresist, has poor stability of the remaining slender photoresist structure, and is extremely prone to photoresist top loss and profile collapse, which leads to subsequent inaccurate measurement of the critical dimension, thereby affecting the effectiveness of process monitoring and product yield.

[0008] Therefore, the technical problem to be solved by the present application is to provide a monitoring pattern that can resist photoresist top loss in the APL-Photo process of a high light transmittance product, thereby achieving stable and reliable critical dimension monitoring.

[0009] To achieve the above-mentioned objects and other related objects, the present application provides a monitoring pattern for a high light transmittance product, which is applied to an additional phase layer-photoetching process in semiconductor manufacturing, and the shape of the monitoring pattern is a circular hole.

[0010] Preferably, the monitoring pattern includes an isolated circular hole pattern and / or a dense circular hole pattern array.

[0011] Preferably, the layout pattern used to define the circular hole monitoring pattern is a square shape.

[0012] Preferably, the high light transmittance product has a light transmittance greater than 90%.

[0013] Preferably, the monitoring pattern is used to monitor the critical dimension by measuring the diameter thereof.

[0014] Correspondingly, the present application also provides a method for using the monitoring pattern for high-transmittance products, comprising the following steps:

[0015] Step one, providing a semiconductor wafer, and forming a layer to be patterned for forming a high-transmittance product on the semiconductor wafer;

[0016] Step two, forming a corresponding photoresist pattern on the layer to be patterned by using a photoetching mask of the monitoring pattern through an additional phase layer-photoetching process;

[0017] Step three, etching the layer to be patterned based on the photoresist pattern to form a structure of the monitoring pattern on the layer to be patterned; and

[0018] Step four, measuring the critical dimension of the structure of the monitoring pattern formed on the layer to be patterned.

[0019] Preferably, in step one, the high-transmittance product has a transmittance greater than 90%.

[0020] Preferably, in step two, the additional phase layer-photoetching process is a process of 28 nanometer or more advanced nodes.

[0021] Preferably, in step four, the measurement of the critical dimension comprises measuring the diameter of the structure of the circular hole pattern.

[0022] Preferably, the circular hole monitoring pattern can reduce the measurement failure caused by photoresist top loss.

[0023] As described above, the monitoring pattern for high-transmittance products and the method for using the same have the following beneficial effects:

[0024] The present application can reduce the measurement failure caused by photoresist top loss. Ultimately, by fundamentally solving the topography fidelity problem of the monitoring pattern in the photoetching step, the present method can effectively avoid the situation that the measurement point cannot be recognized or the measurement data is distorted, significantly improving the success rate and reliability of the online process monitoring, thereby reducing the wafer yield caused by the failure to timely discover the process deviation, and ensuring the production yield and market competitiveness of the high-transmittance products at advanced nodes. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The figure shows the layout of the monitoring pattern of the present application;

[0026] Figure 2 The figure shows the method for using the monitoring pattern of the present application. DETAILED DESCRIPTION

[0027] Other advantages and novel features of the present application will be realized from the following detailed description, which is provided in connection with the attached drawings. Embodiments of the application can be implemented or carried out with additional or other specific embodiments, and in some instances specific embodiments can be practiced without several of the details mentioned in this description. The detailed description is intended to provide a sufficient understanding of the present application to enable one skilled in the art to practice the application.

[0028] The embodiment of the present application provides a monitoring pattern for high-transmittance products, which is applied to an additional phase layer-photoetching (APL-Photo) process in semiconductor manufacturing, and is characterized in that the shape of the monitoring pattern is a circular hole. When a strip-shaped monitoring pattern is used in the scene of removing photoresist by large-area exposure for high-transmittance products, the slender strip-shaped photoresist structure is prone to photoresist top loss, morphology collapse, and even peeling due to poor stability, impact of the developing solution, and stress of subsequent processes, resulting in monitoring failure. The present application innovatively uses a circular hole-shaped monitoring pattern. Due to the geometric symmetry, the pattern has excellent structural stability and stress distribution uniformity, can effectively resist the physical and chemical effects in the developing process, significantly improves the fidelity and anti-deformation ability of the photoresist pattern, and thus ensures that a clear and complete monitoring structure can still be formed in the harsh high-transmittance process environment, providing a reliable basis for subsequent accurate measurement.

[0029] In some embodiments, the monitoring pattern includes a circular hole-shaped pattern arranged in isolation and / or a circular hole-shaped pattern array arranged in high density. By arranging the patterns in two different environments of isolation and high density, different pattern density environments that the actual circuit pattern in the chip may encounter can be more comprehensively simulated, thereby providing more accurate and more representative process monitoring data, effectively capturing process deviations caused by pattern density effects, and making the monitoring result closer to the actual product situation.

[0030] In some embodiments, referring to Figure 1 , the layout pattern used to define the circular hole-shaped monitoring pattern is in the shape of a square. This is a practical approach that conforms to the standard layout design rules in the semiconductor industry. Although the layout design on the photoetching mask is in the shape of a square, through the synergistic effect of the optical proximity effect (OPE) in the photoetching process and the isotropic characteristics of the subsequent etching process, the pattern finally formed on the wafer will naturally present as a circular hole with rounded corners or a near-circular shape. This method simplifies the complexity of layout design and mask manufacturing, reduces manufacturing costs, and at the same time reliably obtains the required circular hole-shaped monitoring structure with excellent structural stability on the wafer.

[0031] In some embodiments, the high-transmittance product has a transmittance greater than 90%. In this context of extremely high transmittance, the area ratio of the photoresist that needs to be removed by development is extremely large, causing the remaining photoresist pattern (i.e., the monitoring pattern) to be in a very unfavorable process environment, and the morphology of the monitoring pattern is extremely prone to collapse. Therefore, the monitoring pattern provided by the present application can particularly embody its significant technical advantages in such applications.

[0032] In some embodiments, the monitoring pattern is used to monitor the critical dimension by measuring the diameter thereof. By periodically measuring the diameter of the circular hole pattern online and comparing it with the set target value, it can be accurately determined whether there is a deviation, such as fluctuation in focal length or exposure energy, in the APL-Photo process and subsequent etching process. Due to the symmetry of the circular hole pattern, the measurement of the diameter thereof is more stable than the line width measurement of the strip pattern and is less susceptible to the directionality of the measurement equipment, so that more accurate and repeatable monitoring data can be obtained, and stable control of the critical dimension at an advanced node can be achieved.

[0033] Referring to Figure 2 The present application also provides a monitoring method for a semiconductor process, comprising the following steps:

[0034] Step one, providing a semiconductor wafer, and forming a layer to be patterned for forming a high-transmittance product on the semiconductor wafer.

[0035] Step two, forming a corresponding photoresist pattern on the layer to be patterned by an additional phase layer-lithography process using a photoresist mask containing the monitoring pattern of any of the above embodiments. In step two, due to the use of the photoresist mask having the circular hole monitoring pattern, the corresponding photoresist pattern formed on the photoresist has stronger structural stability and deformation resistance compared with the conventional strip pattern. Even in the high-transmittance product process where the area ratio of the photoresist to be developed is extremely large, this circular hole photoresist pattern can effectively resist the physical and chemical impact during the development process, significantly reducing the occurrence of photoresist top loss, thereby ensuring the fidelity and integrity of the photoresist pattern, and laying a solid foundation for subsequent accurate pattern transfer.

[0036] Step three, etching the layer to be patterned based on the photoresist pattern to form a structure of the monitoring pattern on the layer to be patterned.

[0037] Step four, measuring the critical dimension of the structure of the monitoring pattern formed on the layer to be patterned.

[0038] In some embodiments, the additional phase layer-lithography process in step two is a process for 28 nanometer or more advanced nodes. These advanced nodes have extremely strict requirements for the control of critical dimensions, and generally use complex techniques such as double or multiple patterning, and have extremely low tolerance for process fluctuations. The monitoring method provided by the present application can effectively cope with the monitoring challenges brought by these advanced processes, and ensure the stability of the process.

[0039] In some embodiments, the high-transmittance product in step one has a transmittance greater than 90%.

[0040] In some embodiments, the critical dimension measurement in step four includes measuring the diameter of the circular hole pattern structure. This not only matches the geometry of the pattern, but also, as previously described, the measurement of the diameter has higher stability and repeatability due to its symmetry, thereby improving the quality of the monitoring data.

[0041] In some embodiments, the use of a circular hole monitoring pattern can reduce measurement failures caused by top loss of photoresist. Ultimately, by fundamentally solving the topography fidelity problem of the monitoring pattern in the lithography step, the method can effectively avoid the situation where the measurement point cannot be recognized or the measurement data is distorted, significantly improving the success rate and reliability of online process monitoring, thereby reducing the wafer yield caused by process drift that is not discovered in time, and ensuring the production yield and market competitiveness of high-transmittance products at advanced nodes.

[0042] It should be noted that the diagrams provided in the present embodiment only illustrate the basic concept of the present application in a schematic manner, and only show the components related to the present application in the diagrams, rather than being drawn according to the number, shape and size of the components when actually implemented. The actual implementation of each component may be arbitrarily changed in terms of its shape, number and proportion, and the layout pattern of the components may also be more complex.

[0043] The above embodiments only illustratively explain the principles and effects of the present application, and are not intended to limit the present application. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical idea disclosed by the present application should be covered by the claims of the present application.

Claims

1. A monitoring pattern for high-transmittance products, applied to the additional phase layer-lithography process in semiconductor manufacturing, characterized in that, The monitoring pattern is in a shape of a circular hole.

2. The monitoring pattern for high-transmittance products according to claim 1, characterized in that: The monitoring pattern comprises a circular hole pattern arranged in isolation and / or a circular hole pattern array arranged in density.

3. The monitoring pattern for high-transmittance products according to claim 1 or 2, characterized in that: A layout pattern used to define the circular hole monitoring pattern is in a square shape.

4. The monitoring pattern for high-transmittance products according to claim 1, characterized in that: The high-transmittance product has a transmittance greater than 90%.

5. The monitoring pattern for high-transmittance products according to claim 1, characterized in that: The monitoring pattern is used to monitor a critical dimension by measuring a diameter thereof.

6. Use of a monitoring pattern for high-transparency products according to any one of claims 1 to 5, characterized in that, At least comprising: Step one, providing a semiconductor wafer and forming a layer to be patterned for forming a high-transmittance product on the semiconductor wafer; Step two, forming a corresponding photoresist pattern on the layer to be patterned by using a photo mask of the monitoring pattern through an additional phase layer-lithography process; Step three, etching the layer to be patterned based on the photoresist pattern to form a structure of the monitoring pattern on the layer to be patterned; and Step four, measuring a critical dimension of the structure of the monitoring pattern formed on the layer to be patterned.

7. The method of using a monitoring pattern for high-transmittance products according to claim 6, characterized in that: In step one, the high-transmittance product has a transmittance greater than 90%.

8. The method of using a monitoring pattern for high-transmittance products according to claim 6, characterized in that: In step two, the additional phase layer-lithography process is a process of a 28-nanometer or more advanced node.

9. The method of using a monitoring pattern for high-transmittance products according to claim 6, characterized in that: In step four, the measurement of the critical dimension comprises measuring a diameter of the structure of the circular hole pattern.

10. The method of using a monitoring pattern for high-transmittance products according to claim 6, characterized in that: The circular hole monitoring pattern can reduce measurement failure caused by photoresist top loss.

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