A correction device and method for correcting focal length of visible light modified step-by-step ultraviolet light exposure

Abstract

The application discloses a correction device and method for correcting focal length of visible light modified step-by-step ultraviolet light exposure, which can be applied to a precise step-by-step ultraviolet light photoetching machine in the field of micro-nano processing. The correction device is composed of a set of correction masks and correction substrates coated with fluorescent substances, and the design of the correction device can find corresponding clear focusing positions under the light sources of ultraviolet light and visible light respectively, so as to correct the focal length of ultraviolet light exposure of the step-by-step photoetching machine using only visible light. The correction device and method can effectively reduce the focal length error of the step-by-step ultraviolet light photoetching machine and improve the resolution of the exposure pattern of micro-nano processing.

Description

[0001] This invention relates to the field of lithography machines in semiconductor exposure processes. More specifically, this invention relates to a correction device and method for visible light correction step-ultraviolet light exposure focal length. Background Technology

[0002] Photolithography is used to manufacture substrates for semiconductor devices, various integrated circuits, flat panel displays (such as liquid crystal displays), circuit boards, biochips, microelectromechanical chips, and optoelectronic circuit chips. The focus error of a photolithography machine is one of the important parameters affecting the processing accuracy of the machine. The focusing time and accuracy play a crucial role in the performance of the photolithography system and the quality of the exposed pattern. In existing focusing methods, visible light focusing is generally used to approximate ultraviolet light focusing. However, due to the difference in wavelengths between visible and ultraviolet light, this method will have certain errors, causing distortion of the exposed pattern at the micro- and nano-scale. Therefore, this invention proposes a correction device and method for visible light correcting the focal length of stepped ultraviolet light exposure. Summary of the Invention

[0003] This invention provides a visible light correction device and method for ultraviolet light exposure focal length correction in stepper lithography machines, so as to facilitate ultraviolet light exposure focal length correction in stepper lithography machines.

[0004] The technical solution adopted in this invention is as follows:

[0005] A correction device design, utilizing a set of correction masks and a correction substrate coated with fluorescent material, can identify the corresponding sharp focus position under both ultraviolet and visible light sources, serving as a focus correction method for ultraviolet exposure in stepper lithography machines that only use visible light for focusing. The design includes the following steps:

[0006] Step 1: The correction device is designed using a set of correction masks and a correction substrate coated with fluorescent material to form a device that can clearly distinguish the focus position.

[0007] Step 2: Illuminate this calibration device under ultraviolet light and visible light sources respectively, and find the positions of the corresponding clear ultraviolet focusing pattern and the general focusing pattern;

[0008] Step 3: Based on the distance difference between the two clearest ultraviolet focusing patterns and the general focusing pattern, obtain the error values ​​of the visible light focal length and the ultraviolet light focal length. This will be used as a correction for the ultraviolet light exposure focal length inside the stepper lithography machine that will only use visible light for focusing in the future, thereby achieving precise focusing of ultraviolet light.

[0009] Preferably, the calibration device includes a stepped calibration device, a planar scale calibration device with an inclined stage, and a general planar calibration device with a stage that moves near and far.

[0010] Preferably, the stepped correction device consists of a three-dimensional stepped correction substrate coated with fluorescent material and a correction mask with multiple sets of numbered or graduated focusing patterns. Each set of focusing patterns on the correction mask can be transferred to the respective step position under the illumination of the light source, and the three-dimensional steps are used to distinguish the precise focal length position.

[0011] Preferably, the use of a three-dimensional stepped structure to distinguish the precise focal length position involves finding the corresponding set of the clearest ultraviolet focusing pattern and the general focusing pattern under ultraviolet and visible light illumination, respectively. Once the stepped positions of the two sets of focusing patterns are confirmed, the error of the ultraviolet and visible light focal length can be calculated.

[0012] Preferably, the planar scale type calibration device consists of a blank calibration substrate coated with fluorescent material and a calibration mask with a focusing pattern design having multiple sets of numbers or scales, and uses the tilt of the stage where the calibration substrate is placed to distinguish the fine focal length position.

[0013] Preferably, the method of using the tilt of the stage where the correction substrate is placed to identify the precise focal length position involves tilting the stage where the correction substrate is placed in the direction of increasing or decreasing number or scale under ultraviolet light and visible light illumination, respectively, to find the corresponding set of the clearest ultraviolet focusing pattern and general focusing pattern, and then converting the ultraviolet and visible light focal length errors by confirming the number or scale positions of the two sets of focusing patterns.

[0014] Preferably, the planar general type correction device consists of a blank correction substrate coated with fluorescent material and a correction mask with a focusing pattern design. The fine focal length position is determined by the up-and-down fine adjustment of the platform where the correction substrate is placed.

[0015] Preferably, the step of using the up-and-down fine adjustment movement of the platform where the correction substrate is placed to identify the fine focal length position involves moving the platform where the correction substrate is placed up and down under ultraviolet light and visible light light respectively, finding the corresponding set of the clearest ultraviolet focusing pattern and general focusing pattern, and confirming the platform movement position of the two sets of focusing patterns to calculate the error of the ultraviolet and visible light focal length.

[0016] Preferably, the focusing pattern on the correction mask can be a square, rectangle, cross, rhombus, star, or other regular polygons, irregular polygons, regular arcs, and irregular arcs.

[0017] Preferably, the source of ultraviolet and visible light can be an ultraviolet mercury lamp with a filter to obtain a visible light source, or multiple LEDs or other point light sources can be used to simultaneously mix ultraviolet and visible light to obtain a source of both ultraviolet and visible light. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0019] Figure 2 The present invention is designed with multiple sets of numbered focusing pattern correction masks;

[0020] Figure 3 The focusing pattern correction mask with scales as described in this invention;

[0021] Figure 4 This is the three-dimensional stepped correction substrate described in this invention;

[0022] Figure 5 The planar correction substrate of the tilting stage described in this invention;

[0023] Figure 6 This is the planar correction substrate that moves with the stage as described in this invention;

[0024] Reference numerals: 1. Visible and ultraviolet mixed light source; 2. Photomask; 3. Multiple optical components; 4. Stage; 5. Correction substrate; 6. Ultraviolet point light source; 7. Visible point light source; 8. Number; 9. Focusing pattern; 10. Scale. Detailed Implementation

[0025] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are merely one embodiment of the present invention, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this application.

[0026] Example 1

[0027] This embodiment takes a calibration substrate that is three-dimensional stepped, a focusing pattern that is cross-shaped, and a focusing pattern on the calibration mask that has multiple sets of numbers as an example, and includes the following steps:

[0028] 1. A correction device design is constructed by using a set of correction masks with multiple numbered numbers and a cross-shaped focus pattern and a stepped correction substrate coated with fluorescent material, which constitutes a device that can clearly distinguish the focus position.

[0029] 2. By illuminating this correction device with ultraviolet light and visible light, the positions of the clear ultraviolet focusing pattern and the general focusing pattern on the stepped correction device can be found.

[0030] 3. Based on the difference in step height between the two clearest ultraviolet focusing patterns and the general focusing pattern, the error values ​​of the visible light focal length and ultraviolet light focal length are obtained.

[0031] 4. This error value will be used as a correction for the ultraviolet light exposure focal length inside the stepper lithography machine that will only use visible light for focusing in the future, thereby achieving accurate focusing of ultraviolet light.

[0032] Example 2

[0033] This embodiment takes a planar calibration substrate that tilts with the stage, a cross-shaped focusing pattern, and a graduated focusing pattern on the calibration mask as an example, and includes the following steps:

[0034] 1. A correction device is designed using a set of correction masks with scales and a cross-shaped focus pattern, and a planar correction substrate coated with fluorescent material that tilts with the stage, to form a device that can clearly distinguish the focus position.

[0035] 2. By illuminating this calibration device with ultraviolet light and visible light, the positions of the clear ultraviolet focusing pattern and the general focusing pattern on the planar calibration device that tilts with the stage can be found.

[0036] 3. Based on the positional distance difference between the two clearest ultraviolet focusing patterns and the general focusing pattern, as well as the stage tilt angle, the error values ​​of the visible light focal length and ultraviolet light focal length are obtained.

[0037] 4. This error value will be used as a correction for the ultraviolet light exposure focal length inside the stepper lithography machine that will only use visible light for focusing in the future, thereby achieving accurate focusing of ultraviolet light.

[0038] Example 3

[0039] This embodiment takes a planar calibration substrate that moves with the stage, a cross-shaped focusing pattern, and a graduated focusing pattern on the calibration mask as an example, and includes the following steps:

[0040] 1. A correction device is designed by using a set of calibration masks with scales and a cross-shaped focus pattern and coated with fluorescent material, which are planar calibration substrates that move with the stage. This device can clearly distinguish the focus position.

[0041] 2. By illuminating this calibration device with ultraviolet light and visible light, the positions of the clear ultraviolet focusing pattern and the general focusing pattern on the planar calibration device, which move with the distance of the stage, can be found respectively.

[0042] 3. Based on the difference in stage movement when finding the two clearest ultraviolet focusing patterns and the general focusing pattern, the error values ​​of the visible light focal length and ultraviolet light focal length are obtained.

[0043] 4. This error value will be used as a correction for the ultraviolet light exposure focal length inside the stepper lithography machine that will only use visible light for focusing in the future, thereby achieving accurate focusing of ultraviolet light.

Claims

1. A method for correcting the focal length of visible light-corrected step-ultraviolet light exposure, characterized in that, Includes the following steps: Step 1: A correction device consisting of a set of correction masks and a correction substrate coated with fluorescent material can be used to identify a clear focus position. Step 2: Place this calibration device under ultraviolet light and visible light sources respectively to find the positions of the corresponding clear ultraviolet focusing pattern and the general focusing pattern; Step 3: Based on the distance difference between the two clearest ultraviolet focusing patterns and the general focusing pattern, obtain the error values ​​of the visible light focal length and the ultraviolet light focal length. This will be used as a correction for the ultraviolet light exposure focal length inside the stepper lithography machine that will only use visible light for focusing in the future, thereby achieving precise focusing of ultraviolet light.

2. A correction device for implementing the correction method for visible light corrected step ultraviolet light exposure focal length as described in claim 1, characterized in that: The correction device is composed of a set of correction masks and a correction substrate coated with fluorescent material. It can find the corresponding clear focus position under ultraviolet light and visible light sources respectively, as a correction of the ultraviolet light exposure focus of a stepper lithography machine that only uses visible light for focusing. The correction device includes a stepped correction device, a planar correction device with an inclined stage, or a general planar correction device with a stage that moves near and far.

3. The calibration device according to claim 2, characterized in that: The stepped correction device consists of a three-dimensional stepped correction substrate coated with fluorescent material and a correction mask with a focus pattern design with multiple sets of numbers or scales. Under the illumination of the light source, each set of focus patterns on the correction mask is transferred to the respective step position, and the three-dimensional steps are used to distinguish the fine focal length position.

4. The calibration device according to claim 3, characterized in that: The method of using a three-dimensional stepped structure to identify the precise focal length position involves finding the corresponding set of the clearest ultraviolet focusing pattern and the general focusing pattern under ultraviolet and visible light illumination, respectively. By confirming the stepped positions of the two sets of focusing patterns, the error of the ultraviolet and visible light focal length can be calculated.

5. The calibration device according to claim 2, characterized in that: The planar correction device of the tilting stage consists of a blank correction substrate coated with fluorescent material and a correction mask with a focus pattern design with multiple sets of numbers or scales. The tilting of the stage where the correction substrate is placed is used to distinguish the fine focal length position.

6. The calibration device according to claim 5, characterized in that: The method of using the tilt of the stage where the correction substrate is placed to identify the precise focal length position involves tilting the stage where the correction substrate is placed in the direction of increasing or decreasing number or scale under ultraviolet light and visible light illumination, respectively, to find the corresponding set of the clearest ultraviolet focusing pattern and general focusing pattern, and then converting the ultraviolet and visible light focal length errors by confirming the number or scale position of the two sets of focusing patterns.

7. The calibration device according to claim 2, characterized in that: The planar general-type correction device with a moving stage consists of a blank correction substrate coated with fluorescent material and a correction mask with a focusing pattern design. The precise focal length position is determined by finely adjusting the up and down movement of the stage where the correction substrate is placed.

8. The calibration device according to claim 7, characterized in that: The method of using the up-and-down fine adjustment of the platform where the correction substrate is placed to identify the precise focal length position involves moving the platform where the correction substrate is placed up and down under ultraviolet light and visible light light, respectively, to find the corresponding set of the clearest ultraviolet focusing pattern and general focusing pattern. By confirming the platform movement position of the two sets of focusing patterns, the error of the ultraviolet and visible light focal length can be calculated.

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