KR100980060B1 - Method for inspection in photomask - Google Patents

Abstract

The inspection method of the photomask of the present invention comprises the steps of preparing a layout of a design layout including a main cell region and a frame region; Forming a phase shift pattern and a light shield pattern on a frame region of the substrate by performing first patterning by applying a layout of a design layout on the substrate; Performing second patterning by applying the stepper mask job data and the stepper on the substrate to partially expose the phase shift pattern of the frame region to form a monitoring pattern; Setting the light blocking layer pattern to be recognized as a dark region, and performing light correction to recognize the phase inversion layer pattern and the substrate as a clear region; Adjusting and setting the bias difference so that the monitoring pattern formed on the substrate and the design data of the secondary patterning coincide; And inspecting whether a foreign material is present in the monitoring pattern by performing a pattern inspection on the monitoring pattern in which the bias difference is adjusted.

Mask job data for stepper, secondary patterning, pattern inspection

Description

Method for inspection in photomask

The present invention relates to a photomask, and more particularly to a method for inspecting a photomask.

In the process of manufacturing a semiconductor device, a layout of a circuit pattern to be actually formed on a wafer is implemented on a photomask, and the implemented layout pattern is transferred onto a wafer using an exposure process. . Recently, as the degree of integration of semiconductor devices increases, the size of a pattern to be formed on a wafer is also reduced as the design rule decreases. Therefore, it is important to precisely form the fine patterns to be transferred to the wafer on the photomask. In addition, an inspection process for checking whether the fine patterns formed on the photomask are correctly formed or a defect occurs in the process of forming the fine patterns is required. The inspection process for the pattern formed on the photomask is performed using a mask inspection equipment.

In general, a mask inspection method which is performed after forming a pattern on a mask is a method of inspecting design data, that is, data of a database (Data Base data) by comparing with a pattern formed on an actual mask. Specifically, after the light blocking film or the phase inversion film is formed on the substrate, the inspection apparatus recognizes the light blocking film or the phase inversion film as a dark area, sets the substrate to be recognized as a clear area, and then transmits the light source. Is examined by inspecting on a pattern. In addition, a method of inspecting different dies (dies or chips) and dies is performed by inspecting a main cell region. Meanwhile, when the second patterning process is performed in the E-Beam exposure apparatus in the process of forming the phase inversion mask, problems such as defects caused by static electricity may occur. In order to improve this, a second patterning process is being performed using a stepper, but it is difficult to form mask job data for the stepper.

1 is a diagram illustrating a mask defect inspection method.

Referring to FIG. 1, a layout of design data including a main cell region 105 in which a die is disposed and a frame region 110 surrounding the die is prepared (see FIG. 1A). In the layout of design data, the first test pattern 115 is disposed on the frame part 110. The first test pattern 115 includes a monitoring pattern for observing a pattern formed in the main cell region 105. Next, the layout of the stepper mask job data is prepared for the secondary patterning process (see FIG. 1B). However, in the process of preparing the mask job data layout of the second patterning process, the first test pattern 115 of the design data may be formed as the second test pattern 120 at a position reflected in the y-axis direction. When the mask is manufactured based on the first test pattern 115 of the design data and the second test pattern 120 of the mask job data of the second patterning, the first and second test patterns 115 and 120 are formed. All are formed on the mask, which can lead to defects in the wafer. However, since the general process verification inspection is performed by inspecting the main cell, it is difficult to inspect the area where the light shielding film is exposed, so it is difficult to inspect the secondary patterning process. Therefore, if the wrong exposure of the light shielding film area is caused by an operator's mistake during job creation, the wafer cannot be detected by inspection and defects in the wafer are generated.

The inspection method of a photomask according to the present invention comprises the steps of preparing a layout of a design layout including a main cell region and a frame region; Forming a phase shift pattern and a light shield pattern on a frame region of the substrate by performing first patterning by applying a layout of the design layout on a substrate; Performing second patterning by applying stepper mask job data and stepper on the substrate to partially expose the phase shift pattern of the frame region to form a monitoring pattern; Setting the light blocking layer pattern to be recognized as a dark region, and performing light correction to recognize the phase inversion layer pattern and the substrate as a clear region; Adjusting and setting the bias difference so that the monitoring pattern formed on the substrate and the design data of the second patterning coincide; And inspecting whether a foreign material is present in the monitoring pattern by performing a pattern inspection on the monitoring pattern in which the bias difference is adjusted.

In the present invention, a test pattern or a monitoring pattern for confirming the progress of the process is arranged on the frame region of the layout of the design layout.

Preferably, the primary patterning is performed using electron beam exposure.

The forming of the monitoring pattern may include forming a resist film filling the phase inversion film pattern and the light blocking film pattern; Performing a lithography process on the resist film to form a resist film pattern for selectively exposing a light blocking film pattern of a region where a monitoring pattern is to be formed in the frame region; And forming a monitoring pattern by etching the light blocking layer pattern in which the resist layer pattern is exposed as an etch mask to expose the phase inversion layer pattern of the frame region.

In the light correction, when the light transmitted by irradiating light onto the substrate is detected, the phase inversion film and the surface of the substrate are set to be recognized as equivalent values.

The adjusting and setting of the bias difference may be performed by bringing data of a design database to a database inspection apparatus, and manually adjusting the pattern according to the pattern while adjusting the bias and the pattern formed on the substrate. A comparable environment can be created.

The checking of the presence or absence of the foreign matter in the monitoring pattern may be performed by recognizing and detecting a pattern defect when the foreign matter exists on the monitoring pattern.

In the step of checking whether the foreign matter is present in the monitoring pattern, when foreign matter is detected on the monitoring pattern, it is preferable to redesign the stepper mask job data to perform the second patterning again.

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

2 to 16 are diagrams for explaining the inspection method of the photomask according to an embodiment of the present invention.

Referring to FIG. 2, a layout diagram 200 of a design layout based on a design database is prepared. The layout 200 of the design layout comprises a main cell region 205 on which a die is disposed and a frame region 210 surrounding the die. A target pattern (not shown) to be transferred to the wafer is disposed in the main cell region 205, and a monitoring pattern 215 for confirming a test pattern or a process progress is disposed in the frame region 210. In the embodiment of the present invention, a method of verifying a test pattern or a monitoring pattern of the frame area 210 during the second patterning will be described. 3 to 16 show individual monitoring patterns formed in the frame area 210. In this case, the monitoring pattern may be formed together while forming the main pattern in the main cell region 205.

Referring to FIG. 3, a phase inversion film 305 and a light blocking film 310 are deposited on the substrate 300. Here, the substrate 300 includes a transparent material capable of transmitting light, for example, quartz. Next, the phase inversion film 305 deposited on the substrate 300 is made of a material capable of inverting the phase of light irradiated onto the substrate in an exposure process to be performed later. The phase inversion film 305 may include a compound containing molybdenum (Mo), for example, a molybdenum silicon oxynitride film (MoSiON). The light blocking layer 310 formed on the phase inversion layer 305 blocks light transmitted through the substrate 300 in an exposure process to be performed later. The light blocking film 310 may be formed to include a chromium film Cr. Next, a first resist film 315 is formed over the light blocking film 310. The first resist layer 315 may serve as an etch mask in an etching process of etching a lower layer, for example, the light blocking layer 310 and the phase inversion layer 305, to form a mask layer pattern.

Referring to FIG. 4, a first lithography process may be performed on the first resist layer 315 (see FIG. 3) to form a first resist layer pattern 320 that selectively exposes the light blocking layer 310. . Specifically, an exposure process is performed on the first resist film 315. Then, a difference in solubility occurs depending on whether or not the photochemical reaction of the portion irradiated with light and the portion not irradiated with light occurs on the first resist layer 315. Next, when the development process is performed, the resist film of the portion in which the solubility difference occurs is removed by the developer, thereby forming a first resist film pattern 320 that selectively exposes the surface of the light blocking film 310. Here, the first lithography process may proceed to selective exposure using an electron beam (E-beam) exposure.

Referring to FIG. 5, first patterning using the first resist film pattern 320 is performed. In detail, an exposed portion of the light blocking layer 310 is etched using the first resist layer pattern 320 as an etch mask to form a light blocking layer pattern 325 partially exposing the phase inversion layer 305. Subsequently, the exposed portion of the phase shift film 305 is etched using the first resist film pattern 320 and the light blocking film pattern 325 as an etch mask to form the phase shift film pattern 330.

Referring to FIG. 6, the first resist layer pattern 320 is removed by performing a strip process. Accordingly, the surface of the substrate 300 is selectively exposed by the phase inversion film pattern 330 and the light blocking film pattern 325. The first resist layer pattern 320 generally proceeds with a strip method of oxidizing and removing a resist using an oxygen (O ₂ ) plasma, but is not limited thereto.

Referring to FIG. 7, a second resist film 335 is formed on the substrate 300 on which the phase inversion film pattern 330 and the light blocking film pattern 325 are formed. The second resist film 335 is formed to have a sufficient thickness to fill the phase inversion film pattern 330 and the light blocking film pattern 325.

Referring to FIG. 8, a second lithography process is performed on the second resist film 335 to form a second resist film pattern 340 that serves as a mask in the second patterning. Specifically, an exposure process is performed on the second resist film 335. Then, a difference in solubility occurs depending on whether or not the photochemical reaction of the portion irradiated with light and the portion not irradiated with light occurs on the second resist layer 335. Next, when the development process is performed, the resist film of the portion where the solubility difference is generated is removed by the developer. Accordingly, a second resist film pattern 340 is formed to selectively expose the light blocking film pattern 335a of the region 345 on which the monitoring pattern is to be formed, and to block the light blocking film pattern 335b of the other region 350. do. Here, the secondary lithography process can proceed to a mask projection system using a mask job data for stepper and a stepper. The stepper can achieve the desired shape size with a mask of low resolution because reduced projection is used.

9 and 10, second patterning using the second resist layer pattern 340 as a mask is performed to remove the light blocking layer pattern 335a of the region 345 on which the monitoring pattern is to be formed. Then, as shown in FIG. 10, the phase shift film pattern, that is, the monitoring pattern 330a is exposed on the frame area. In this case, the frame region of the remaining portion except for the region where the monitoring pattern 330a is disposed is covered with the light blocking layer pattern 335b. On the other hand, the stepper mask job data may not be designed properly, so that a residue of the light blocking film pattern may remain on the monitoring pattern 335a. Here, the parts not described in the drawing are the main area 205.

As a result, as shown in Figs. 11 to 14, the verification process is performed on the secondary patterning which is applied by applying the stepper mask job data. The verification process checks the design data by comparing the pattern formed on the actual substrate. To this end, first, as shown in FIG. 11, a light calibration is performed to set the phase inversion film MoSiON and the surface of the substrate Quartz to be recognized as equivalent values. When light correction is performed on the light blocking film Cr and the phase inversion film MoSiON, the dark area and the clear area are set to recognize the pattern. Here, as shown in FIG. 12, the optical correction generally proceeds by setting the light blocking film Cr and the substrate Quartz to be recognized or by setting the phase shift film MoSiON and the Quartz to be recognized. come. However, in the verification process for the second patterning, three layers, not two layers, need to be inspected. Therefore, the phase inversion film MoSiON and the substrate Quartz must be recognized in the same manner before the inspection can be performed. Accordingly, the optical correction is performed to set the phase inversion film MoSiON and the surface of the substrate Quartz to be recognized as equivalent values. Then, the light blocking film Cr is set to a dark area on the recognition screen of the inspection apparatus, and the phase inversion film MoSiON and the substrate Quartz are set to the clear area. The pattern inspection is performed by irradiating a transmission light source onto the pattern.

Next, as shown in FIG. 13, the bias pattern is adjusted by setting the second patterning design data 400 in accordance with the pattern formed on the mask 410 which is actually subjected to the second patterning. Here, the parts not described in the drawings are the light blocking film patterns 405a and 405b and the monitoring patterns 415a and 415b covering the frame area. Referring to FIG. 14, which shows the adjustment of the bias difference in the actual inspection equipment, the data of the design database is loaded into the database inspection device to adjust the bias in detail with the mask (a). Adjustable (b). Accordingly, by adjusting a bias value in the inspection apparatus, an environment that can be compared with a mask can be created by adjusting a minute difference of a pattern. On the other hand, the part about the sensitivity to bias difference can be ignored even if the defect of 5 micrometers or more is ignored, and can detect to at least 0.3 micrometer.

Next, referring to FIGS. 15A and 15B, a pattern check is performed by the database checking device. Pattern inspection proceeds in a manner that irradiates light onto the substrate and detects transmitted light, and verifies black / white. Referring to FIG. 15A, which shows a result of inspecting a phase inversion film MoSiON, it may be confirmed that particles are detected. The particle detected here is a screen in which the foreign material existing on the phase inversion film is recognized as a defective pattern, instead of detecting the phase inversion film as a defect. This is because the light blocking film and the phase inversion film are optically corrected, so that the phase inversion film and the substrate are saturated and recognized as clear areas. That is, the screen recognized as a bad pattern may be determined as an area in which the light blocking layer remains on the phase inversion layer. In addition, in the case of FIG. 15B, which is a screen showing the result of inspecting the substrate Quartz as an image, the detected particle is a detection screen in which a foreign material on the substrate is recognized as a pattern defect, not detected as a defect. Accordingly, the detection screen recognized as a defective pattern may be determined as a region where the light blocking film remains on the substrate.

As such, when it is confirmed that the foreign matter is generated in the inspection apparatus, since an error occurs in the secondary patterning process, the mask job data for the stepper applied in the secondary patterning process is redesigned, and then the secondary patterning process is performed again. The second patterning process may be formed by removing the exposed phase shift pattern, depositing the phase shift layer on the removed portion, and then performing a patterning process. When no foreign matter is detected in the verification test of the second patterning process, as illustrated in FIG. 16, the second resist film pattern 340 is removed to block the frame region by the light blocking film pattern 335b, thereby testing the pattern. This formed phase inversion mask can be manufactured.

The photomask inspection method according to the present invention is a method of verifying a secondary patterning process using the stepper mask job data, and performing a patterning verification process by adding a step of overlapping the test layout and the stepper mask job data. The process then proceeds to create a mask. Here, the second patterning process is performed using a stepper, and then a database inspection is introduced and verified. Accordingly, the quality of the mask can be improved by detecting defects in portions of the test pattern of the wafer and other verification circuits for measurement. In addition, problems resulting from the step process on the wafer can be measured to apply subsequent processes.

1 is a diagram illustrating a mask defect inspection method.

2 to 16 are diagrams for explaining the inspection method of the photomask according to an embodiment of the present invention.

Claims (8)

Preparing a layout of a design layout including a main cell region and a frame region; Forming a phase shift pattern and a light shield pattern on a frame region of the substrate by performing first patterning by applying a layout of the design layout on a substrate; Performing second patterning by applying mask step data and stepper for stepper on the substrate to form a monitoring pattern by partially exposing a phase shift pattern of the frame region; Setting the light blocking layer pattern to be recognized as a dark region, and performing light correction to recognize the phase inversion layer pattern and the substrate as a clear region; Import the data from the design database into the database inspection device and match the design data corresponding to the pattern to be formed in the secondary patterning with the monitoring pattern actually formed on the substrate to create an environment that can be compared with the pattern formed on the substrate. step; And Inspecting the photomask for inspecting the presence or absence of foreign substances in the monitoring pattern by performing a pattern inspection on the monitoring pattern. The method of claim 1, And a monitoring pattern capable of confirming a test pattern or a process progress on the frame region of the layout of the design layout. The method of claim 1, And the first patterning is performed using electron beam exposure. The method of claim 1, wherein the forming of the monitoring pattern comprises: Forming a resist film filling the phase shift film pattern and the light blocking film pattern; Performing a lithography process on the resist film to form a resist film pattern for selectively exposing a light blocking film pattern of a region where a monitoring pattern is to be formed in the frame region; And And etching the light-blocking film pattern in which the resist film pattern is exposed as an etch mask to expose a phase inversion film pattern in the frame region to form a monitoring pattern. The method of claim 1, The light compensation is a method of inspecting a photomask that is set to recognize the surface of the phase inversion film and the substrate to equal values when detecting the transmitted light by irradiating light on the substrate. delete The method of claim 1, The checking of the presence or absence of a foreign material in the monitoring pattern may include detecting and detecting as a pattern defect when a foreign material exists on the monitoring pattern. The method of claim 1, The checking of the presence or absence of a foreign material in the monitoring pattern may include redesigning the stepper mask job data when the foreign material is detected on the monitoring pattern to perform the second patterning again.

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