An integration uniformity compensation method, compensation device and lithography equipment

Abstract

Embodiments of the present invention disclose an integration uniformity compensation method, a compensation device, and a lithography apparatus. The integration uniformity compensation method includes: acquiring light intensity data of the entire field of view; calculating the integration uniformity of the light field according to the light intensity data; calculating a first compensation amount required for uniformity according to the integration uniformity; calculating a second compensation amount required for uniformity according to the imaging relationship of the imaging unit; calculating the topography of the compensation mask according to the first compensation amount and the second compensation amount; preparing the compensation mask according to the topography of the compensation mask, and inserting the compensation mask into the exposure system for integration uniformity compensation. The integration uniformity compensation method provided by the embodiments of the present invention can simplify the compensation process, ensure the reliability of the integration uniformity compensation, reduce the compensation cost, improve the consistency of the integration uniformity of each stitched field of view, ensure that each field of view is exposed under the best integration uniformity, and improve the product manufacturing quality.

Description

Technical Field

[0001] Embodiments of the present invention relate to semiconductor manufacturing technologies, and in particular, to an integral uniformity compensation method, a compensation device, and a lithography apparatus. Background Art

[0002] Lithography technology is a technology for printing a pattern with features on the surface of a substrate. Such a substrate may include substrates for manufacturing semiconductor devices, various integrated circuits, flat panel displays (such as liquid crystal displays), circuit boards, biochips, microelectromechanical chips, optoelectronic circuit chips, etc. Commonly used substrates are semiconductor wafers or glass substrates coated with photosensitive media on the surface.

[0003] In the lithography process, a wafer is placed on a wafer stage, and through an exposure system in a lithography apparatus, a pattern with features is projected onto the surface of the wafer. The illumination system of existing lithography apparatuses generally requires the light field uniformity to reach within 1%, and the requirements and difficulties for design and processing are very strict. Even if a quartz rod or a microlens array is set for light homogenization, according to actual assembly and adjustment experience, it cannot ensure that the illumination field uniformity of all units reaches the requirements simultaneously. To improve the uniformity of the light beam, a compensation plate can be set in the optical path. However, in the prior art, the topography of the compensation plate is usually obtained according to the deconvolution algorithm. The traditional compensation convolution process is complex, the calculation error is large, resulting in a high cost. Summary of the Invention

[0004] Embodiments of the present invention provide an integral uniformity compensation method, a compensation device, and a lithography apparatus. This method can simplify the compensation process, ensure the reliability of integral uniformity compensation, reduce the compensation cost, improve the consistency of the integral uniformity of each stitching field of view, ensure that each field of view is exposed under the best integral uniformity, and improve the product manufacturing quality.

[0005] In a first aspect, embodiments of the present invention provide an integral uniformity compensation method, including:

[0006] Obtain the light intensity data of the entire field of view;

[0007] Calculate the integral uniformity of the light field according to the light intensity data;

[0008] Calculate a first compensation amount required for uniformity according to the integral uniformity;

[0009] Calculate a second compensation amount required for uniformity according to the imaging relationship of the imaging unit;

[0010] Calculate the topography of the compensation plate according to the first compensation amount and the second compensation amount;

[0011] Prepare a compensation plate according to the topography of the compensation plate, and insert the compensation plate into the exposure system for integral uniformity compensation.

[0012] Optionally, the field of view includes a single field of view or a stitched field of view of multiple fields of view.

[0013] Optionally, calculating the second compensation amount for the uniformity requirement according to the imaging relationship of the imaging unit includes:

[0014] Simulating the convolution result when light passes through the imaging unit according to the optical model;

[0015] Calculating the second compensation amount for the uniformity requirement according to the convolution result and the magnification of the imaging unit.

[0016] Optionally, calculating the topography of the compensation plate according to the first compensation amount and the second compensation amount includes:

[0017] Obtaining the difference between the first compensation amount and the second compensation amount;

[0018] Calculating the topography of the compensation plate according to the difference.

[0019] In a second aspect, an integral uniformity compensation device provided by an embodiment of the present invention further includes an exposure system, and the exposure system includes a light source, a coupling mirror group, a light homogenizing unit, an imaging unit, and a projection objective lens that are sequentially arranged along the light propagation direction;

[0020] The light source is used to emit an illumination beam, the coupling mirror group is used to couple the illumination beam into the light homogenizing unit, the light homogenizing unit is used to homogenize the outgoing beam of the coupling mirror group, and the imaging unit is used to match the field of view and numerical aperture of the outgoing light of the light homogenizing unit with the field of view and numerical aperture of the projection objective lens;

[0021] The integral uniformity compensation device further includes a compensation plate, the compensation plate is arranged in the optical path on the light-emitting side of the light homogenizing unit, and the compensation plate is used to perform integral uniformity compensation on the outgoing beam of the light homogenizing unit.

[0022] Optionally, the compensation plate is located between the light homogenizing unit and the imaging unit.

[0023] Optionally, it further includes a first convex lens, the first convex lens is located between the light homogenizing unit and the compensation plate, and the distance between the light-emitting surface of the light homogenizing unit and the first convex lens and the distance between the compensation plate and the first convex lens are both 2F1, where F1 represents the focal length of the first convex lens.

[0024] Optionally, it further includes a second convex lens and a third convex lens sequentially arranged along the light propagation direction. Both the second convex lens and the third convex lens are located between the light homogenizing unit and the compensation plate. The distances between the light exit surface of the light homogenizing unit, the second convex lens, the third convex lens, and the compensation plate are all F2, where F2 represents the focal lengths of the second convex lens and the third convex lens.

[0025] Optionally, the compensation plate is located on the light exit side of the imaging unit.

[0026] In a third aspect, an embodiment of the present invention further provides a lithography apparatus, including the integrated uniformity compensation device described in any one of the above.

[0027] The integrated uniformity compensation method provided by the embodiment of the present invention first obtains the light intensity data of the entire field of view; then calculates the integrated uniformity of the light field according to the light intensity data; calculates the first compensation amount required for uniformity according to the integrated uniformity; calculates the second compensation amount required for uniformity according to the imaging relationship of the imaging unit; calculates the topography of the compensation plate according to the first compensation amount and the second compensation amount; prepares the compensation plate according to the topography of the compensation plate, and inserts the compensation plate into the exposure system for integrated uniformity compensation. The integrated uniformity compensation method provided in this embodiment can simplify the compensation process, ensure the reliability of the integrated uniformity compensation, reduce the compensation cost, improve the consistency of the integrated uniformity of each stitched field of view, ensure that each field of view is exposed under the best integrated uniformity, and improve the product manufacturing quality. Description of the Drawings

[0028] Figure 1 It is a schematic flowchart of an integrated uniformity compensation method provided by an embodiment of the present invention;

[0029] Figure 2 It is a schematic structural diagram of a field stop provided by an embodiment of the present invention;

[0030] Figure 3 It is a schematic diagram of the integrated uniformity corresponding to the working condition with poor simulated integrated uniformity;

[0031] Figure 4 It is a schematic diagram of the topography of a compensation plate provided by an embodiment of the present invention;

[0032] Figure 5 It is a schematic diagram of the result after compensating the uniformity of the simulated machine tool;

[0033] Figure 6 It is a schematic structural diagram of an integrated uniformity compensation device provided by an embodiment of the present invention;

[0034] Figure 7 It is a schematic diagram of the mechanical tooling for feature point alignment;

[0035] Figure 8 The fine-tuning sensitivity of the integral uniformity for a single field of view;

[0036] Figure 9 The partial structural schematic diagram of an integral uniformity compensation device provided by an embodiment of the present invention;

[0037] Figure 10 The partial structural schematic diagram of another integral uniformity compensation device provided by an embodiment of the present invention;

[0038] Figure 11 The structural schematic diagram of another integral uniformity compensation device provided by an embodiment of the present invention. Specific embodiments

[0039] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. In addition, it should be noted that for the convenience of description, only the parts related to the present invention are shown in the drawings, rather than all the structures.

[0040] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, rather than aiming to limit the present invention. It should be noted that the orientation terms such as "upper", "lower", "left", and "right" described in the embodiments of the present invention are described from the angles shown in the drawings, and should not be construed as limiting the embodiments of the present invention. In addition, in the context, it should also be understood that when it is mentioned that an element is formed "on" or "under" another element, it can not only be directly formed "on" or "under" another element, but also be indirectly formed "on" or "under" another element through an intermediate element. The terms "first", "second", etc. are only used for descriptive purposes, and do not indicate any order, quantity, or importance, but are only used to distinguish different components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] Figure 1 The flowchart of an integral uniformity compensation method provided by an embodiment of the present invention, refer to Figure 1 , the integral uniformity compensation method provided in this embodiment includes the following steps:

[0042] Step S110: Obtain the light intensity data of the entire field of view.

[0043] It can be understood that the integral uniformity compensation method provided in this embodiment is used in the exposure system of a lithography apparatus for compensating for the deterioration of the integral uniformity of the exposure system. Optionally, the field of view includes a single field of view or a tiled field of view composed of multiple fields of view, that is, this integral uniformity compensation method can be applied to the compensation of integral uniformity for a single field of view and tiled multiple fields of view. Specifically, a light homogenizing unit and a field stop are generally provided in the exposure system, and the desired field of view size and shape can be obtained through the field stop. Exemplarily, Figure 2 is a schematic structural diagram of a field stop provided in an embodiment of the present invention. The light homogenizing unit can be a light homogenizing quartz rod, and the light intensity data obtained here is the light intensity data formed by the field stop at the output end of the light homogenizing quartz rod.

[0044] Step S120: Calculate the integral uniformity of the light field according to the light intensity data.

[0045] After obtaining the light intensity data of the field of view, the integral uniformity of the entire light field can be calculated using a computer. The specific calculation method can be implemented using existing methods for calculating integral uniformity, and the embodiments of the present invention do not limit this.

[0046] Step S130: Calculate the first compensation amount required for uniformity according to the integral uniformity.

[0047] After obtaining the integral uniformity of the entire light field, it can be known which positions in the light field have integral uniformity that does not meet the requirements. For regions where the integral uniformity does not meet the requirements, a compensation algorithm needs to be designed. Specifically, during implementation, algorithm programming can be performed using Matlab to calculate the first compensation amount required for uniformity.

[0048] Step S140: Calculate the second compensation amount required for uniformity according to the imaging relationship of the imaging unit.

[0049] Among them, the imaging unit is used to match the field of view and numerical aperture of the light homogenizing unit output with the field of view and numerical aperture of the projection objective. The imaging unit can include a relay lens group. When designing the compensation algorithm, the convolution process is directly transformed into the convolution process of an object passing through the relay lens group; and in the design of the exposure system, the imaging effect of the relay lens group is known.

[0050] Optionally, calculating the second compensation amount required for uniformity according to the imaging relationship of the imaging unit includes:

[0051] Simulate the convolution result when light rays pass through the imaging unit according to the optical model;

[0052] Calculate the second compensation amount required for uniformity according to the convolution result and the magnification of the imaging unit.

[0053] Step S150: Calculate the topography of the compensation mask according to the first compensation amount and the second compensation amount.

[0054] After obtaining the first compensation amount and the second compensation amount, the compensation amount (the first compensation amount) required for uniformity is calculated using the collected integral uniformity distribution, and then the influence after relay convolution (the second compensation amount) is removed to obtain the final topography of the designed compensation plate.

[0055] Optionally, calculating the topography of the compensation plate according to the first compensation amount and the second compensation amount includes:

[0056] Obtain the difference between the first compensation amount and the second compensation amount;

[0057] Calculate the topography of the compensation plate according to the difference.

[0058] Step S160: Prepare a compensation plate according to the topography of the compensation plate, and insert the compensation plate into the exposure system for integral uniformity compensation.

[0059] During the calculation process, since the compensation plate is placed at the defocus position of the object plane of the relay lens group, the compensation effect of the compensation plate calculated according to the relay magnification may not be ideal; to optimize the compensation effect, the error caused by defocus must be removed in the algorithm; through simulation verification, when it is the fourth root of 4 / 3 of the length of the compensation plate at the corresponding position, the compensation effect is optimal; Figure 3 It is a schematic diagram of integral uniformity corresponding to the working condition with poor simulation integral uniformity, and its integral uniformity is 7.16%. Figure 4 It is a schematic diagram of the topography of a compensation plate provided by an embodiment of the present invention, where the shaded part is the light-blocking area. Figure 5 It is a schematic diagram of the result after compensating the machine table uniformity of the simulation, and its integral uniformity is 0.61%. During the compensation process of the actual machine table, the integral uniformity of a single field of view can be compensated from 2.16% to 0.5%, and a good integral uniformity compensation effect can be obtained.

[0060] The technical solution of this embodiment first obtains the light intensity data of the entire field of view; then calculates the integral uniformity of the light field according to the light intensity data; calculates the first compensation amount required for uniformity according to the integral uniformity; calculates the second compensation amount required for uniformity according to the imaging relationship of the imaging unit; calculates the topography of the compensation plate according to the first compensation amount and the second compensation amount; prepares a compensation plate according to the topography of the compensation plate, and inserts the compensation plate into the exposure system for integral uniformity compensation. The integral uniformity compensation method provided by this embodiment can simplify the compensation process, ensure the reliability of integral uniformity compensation, reduce the compensation cost, improve the consistency of the integral uniformity of each tiled field of view, ensure that each field of view is exposed under the best integral uniformity, and improve the product manufacturing quality.

[0061] Figure 6The figure is a schematic structural diagram of an integration uniformity compensation device provided by an embodiment of the present invention. The integration uniformity compensation device provided by this embodiment is applicable to implementing the integration uniformity compensation method provided by the above embodiment. Refer to Figure 6 , the integration uniformity compensation device provided by this embodiment includes an exposure system 1. The exposure system 1 includes a light source 11, a coupling lens group 12, a light homogenizing unit 13, an imaging unit 14, and a projection objective 15 that are sequentially arranged along the light propagation direction. The light source 11 is used to emit an illumination beam. The coupling lens group 12 is used to couple the illumination beam into the light homogenizing unit 13. The light homogenizing unit 13 is used to homogenize the output beam of the coupling lens group 12. The imaging unit 14 is used to match the field of view and numerical aperture of the output of the light homogenizing unit 13 with the field of view and numerical aperture of the projection objective 15. The integration uniformity compensation device further includes a compensation plate 2. The compensation plate 2 is arranged in the optical path on the light-emitting side of the light homogenizing unit 13. The compensation plate 2 is used to perform integration uniformity compensation on the output beam of the light homogenizing unit 13.

[0062] Among them, the light source 11 can be a mercury lamp, the illumination beam can be an ultraviolet beam, and an ellipsoidal reflector can be arranged between the light source 11 and the coupling lens group 12 for light collection. The coupling lens group 12 includes multiple lenses and is used to collect as much light as possible into the light homogenizing unit 13, Figure 6 Taking the coupling lens group 12 including three lenses as an example is for illustration and does not limit the embodiments of the present invention. Figure 6 The optical axes of the coupling lens group 12 and the light homogenizing unit 13 are perpendicular in Figure 6 and the direction of the light beam can be changed by using structures such as reflectors and reflecting prisms ( Figure 6 not shown in the figure), and can be designed according to the actual situation during specific implementation. The light homogenizing unit 13 can include a light homogenizing quartz rod or a microlens array and is used to homogenize the output beam of the coupling lens group 12. The imaging unit 14 includes a relay lens group with a preset magnification and can be used to match the field of view size and numerical aperture NA. The projection objective 15 projects the light beam onto the wafer to be exposed. The compensation plate 2 is formed by the integration uniformity compensation method provided by the above embodiment and performs integration uniformity compensation on the output beam of the light homogenizing unit 13.

[0063] During specific implementation, in order to achieve the compensation of the integration uniformity of the entire field of view, it is necessary to align the coordinates of each field of view; at the same time, in order to make up for the difference in the integration uniformity of each field of view, the integration uniformity of a single field of view is finely adjusted.

[0064] Before compensation, feature points are placed at the position of the compensation plate for imaging, thereby determining the actual coordinates of each field of view, Figure 7 is a schematic diagram of a mechanical tooling for feature point alignment. After aligning the compensation plate with the actual field of view, the fine-tuning sensitivity of the integration uniformity of a single field of view is simulated by an optical model. Exemplarily, Figure 8The fine-tuning sensitivity of the integral uniformity for a single field of view. Through the adjustment of the integral uniformity of each field of view, the compensation of the integral uniformity of the stitched field of view is achieved; in the actual implementation process, the integral uniformity of the stitched field of view of the machine tool is 4.16% and after single-field compensation and whole-field adjustment, it is integrated to 1.53%, meeting the index requirements.

[0065] In the technical solution of this embodiment, the illumination beam is emitted by the light source, the illumination beam is coupled into the light homogenizing unit through the coupling lens group, the light homogenizing unit homogenizes the outgoing beam of the coupling lens group, the integral uniformity compensation is performed on the outgoing beam of the light homogenizing unit through the compensation plate, and the field of view and numerical aperture of the light homogenizing unit are matched with the field of view and numerical aperture of the projection objective through the imaging unit, ensuring the reliability of the integral uniformity compensation, reducing the compensation cost, improving the consistency of the integral uniformity of each stitched field of view, ensuring that each field of view is exposed under the best integral uniformity, and improving the product manufacturing quality.

[0066] Based on the above technical solution, optionally, continue to refer to Figure 6 , the compensation plate 2 is located between the light homogenizing unit 13 and the imaging unit 14.

[0067] By setting the compensation plate 2 between the light homogenizing unit and the imaging unit 14, the compensation convolution process can be simplified. When designing the compensation algorithm, the convolution process is directly transformed into the convolution process of the object passing through the relay lens group; and the imaging effect of the relay lens group is clear, thus simplifying the compensation algorithm and reducing the cost.

[0068] In the above embodiment, since the compensation plate is placed at the defocus position of the relay object plane, the compensation effect of the compensation plate calculated according to the relay magnification is not ideal; to optimize the compensation effect, the error caused by defocus must be removed in the algorithm. To achieve zero defocus amount, a transfer imaging module can be added to the system to image the rear end of the light homogenizing unit. The position where the compensation plate is placed at the image plane position of the light homogenizing unit is also the object side of the relay. To reduce the impact on imaging, the magnification of the image formed by the transfer is 1. Therefore, the light homogenizing unit and the compensation plate can be respectively placed at the 2F of a lens. Exemplarily, Figure 9 This is a partial structural schematic diagram of an integral uniformity compensation device provided by an embodiment of the present invention. Referring to Figure 9 , optionally, the integral uniformity compensation device provided by this embodiment further includes a first convex lens 3. The first convex lens 3 is located between the light homogenizing unit 13 and the compensation plate 2. The distance between the light-emitting surface of the light homogenizing unit 13 and the first convex lens 3 and the distance between the compensation plate 2 and the first convex lens 3 are both 2F1, where F1 represents the focal length of the first convex lens 3. Through this setting, the compensation error caused by defocus can be eliminated.

[0069] To reduce the imaging distance in the above embodiments, imaging can be performed using two lenses with the same focal length. The light homogenizing unit and the compensation plate can be respectively placed at the focal points of the two lenses. Exemplarily, Figure 10 FIG. is a partial structural schematic diagram of another integral uniformity compensation device provided by an embodiment of the present invention. Refer to Figure 10 , optionally, the integral uniformity compensation device provided in this embodiment further includes a second convex lens 4 and a third convex lens 5 sequentially arranged along the light propagation direction. Both the second convex lens 4 and the third convex lens 5 are located between the light homogenizing unit 13 and the compensation plate 2. The distances between the light-emitting surface of the light homogenizing unit 13, the second convex lens 4, the third convex lens 5, and the compensation plate 2 are all F2, where F2 represents the focal lengths of the second convex lens 4 and the third convex lens 5. Through this setting, the compensation error caused by defocus can also be eliminated.

[0070] In another embodiment, the compensation plate can also be placed at the front end position of the mask plate. Exemplarily, Figure 11 FIG. is a structural schematic diagram of another integral uniformity compensation device provided by an embodiment of the present invention. Refer to Figure 11 , optionally, the compensation plate 2 is located on the light-emitting side of the imaging unit 14, and the compensation plate topography is calculated using the convolution and deconvolution algorithms according to the distance between the compensation plate and the mask plate for compensation.

[0071] An embodiment of the present invention further provides a lithography apparatus, including any one of the integral uniformity compensation devices provided in the above embodiments. The exposure beam in the lithography apparatus provided in this embodiment has good integral uniformity, which can ensure that each field of view is exposed under the best integral uniformity, improving the product manufacturing quality.

[0072] Note that the above is only the preferred embodiment of the present invention and the applied technical principle. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein. Various obvious changes, re-adjustments, and substitutions can be made by those skilled in the art without departing from the protection scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments. Without departing from the concept of the present invention, more other equivalent embodiments can be included, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. An integral uniformity compensation method, characterized in that, Comprising: Obtaining the light intensity data of the entire field of view; Calculating the integral uniformity of the light field according to the light intensity data; Calculating a first compensation amount for the uniformity requirement according to the integral uniformity; Calculating a second compensation amount for the uniformity requirement according to the imaging relationship of the imaging unit; Calculating the topography of the compensation plate according to the first compensation amount and the second compensation amount; Preparing a compensation plate according to the topography of the compensation plate, and inserting the compensation plate into the exposure system for integral uniformity compensation; The calculating a second compensation amount for the uniformity requirement according to the imaging relationship of the imaging unit includes: Simulating the convolution result of the light beam passing through the imaging unit according to the optical model; Calculating a second compensation amount for the uniformity requirement according to the convolution result and the magnification of the imaging unit.

2. The integral uniformity compensation method according to claim 1, wherein The field of view includes a single field of view or a stitched field of view of multiple fields of view.

3. The integral uniformity compensation method according to claim 1, characterized in that The calculating the topography of the compensation plate according to the first compensation amount and the second compensation amount includes: Obtaining the difference between the first compensation amount and the second compensation amount; Calculating the topography of the compensation plate according to the difference.

4. An integral uniformity compensation device, characterized in that, Including an exposure system, the exposure system includes a light source, a coupling mirror group, a light homogenizing unit, an imaging unit, and a projection objective lens sequentially arranged along the light propagation direction; The light source is used for emitting an illumination beam, the coupling mirror group is used for coupling the illumination beam into the light homogenizing unit, the light homogenizing unit is used for homogenizing the output beam of the coupling mirror group, and the imaging unit is used for matching the field of view and numerical aperture of the output of the light homogenizing unit with the field of view and numerical aperture of the projection objective lens; The integral uniformity compensation device further includes a compensation plate, the compensation plate is arranged in the optical path on the light output side of the light homogenizing unit, and the compensation plate is used for performing integral uniformity compensation on the output beam of the light homogenizing unit; The compensation plate is formed according to the integral uniformity compensation method described in claim 1.

5. The integral uniformity compensation device according to claim 4, characterized in that, The compensation plate is located between the light homogenizing unit and the imaging unit.

6. The integral uniformity compensation device according to claim 5, characterized in that Further including a first convex lens, the first convex lens is located between the light homogenizing unit and the compensation plate, and the distance between the light output surface of the light homogenizing unit and the first convex lens and the distance between the compensation plate and the first convex lens are both 2F1, where F1 represents the focal length of the first convex lens.

7. The integral uniformity compensation device according to claim 5, characterized in that, Further including a second convex lens and a third convex lens sequentially arranged along the light propagation direction, both the second convex lens and the third convex lens are located between the light homogenizing unit and the compensation plate, and the distances between the light output surface of the light homogenizing unit, the second convex lens, the third convex lens, and the compensation plate are all F2, where F2 represents the focal lengths of the second convex lens and the third convex lens.

8. The integral uniformity compensation device according to claim 4, wherein The compensation plate is located on the light output side of the imaging unit.

9. A lithographic apparatus, characterized in that, Including the integral uniformity compensation device according to any one of claims 4 to 8.

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