Method for cleaning immersion cover of photoetching machine by using standard wafer

Abstract

The invention provides a method for cleaning an immersion cover of a photoetching machine by using a standard wafer. The method for cleaning the immersion cover of the photoetching machine by using the standard wafer comprises the following steps: providing the standard wafer, wherein the surface of the standard wafer is provided with a groove pattern; and placing the standard wafer in a photoetching machine for virtual exposure, and in the virtual exposure process, clamping impurities in an immersion cover of the photoetching machine by the groove pattern so as to bring the impurities out of the immersion cover. In this way, impurities in the immersion cover can be effectively removed, the purpose of cleaning the immersion cover is achieved, shutdown is not needed, the cleaning efficiency can be improved, and the influence of cleaning of the immersion cover on the productivity of the photoetching machine is reduced.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and particularly to a method for using a standard wafer to clean an immersion hood of a lithography machine. Background Art

[0002] In the integrated circuit process, a lithography machine is usually used to transfer the pattern formed on a mask or a reticle to the photoresist layer on a wafer. Currently, deep ultraviolet (DUV) 193nm wavelength lithography machines are mainly divided into two types, immersion and dry lithography machines. The main difference lies in the different numerical apertures (NA) of the lenses. According to the Rayleigh criterion formula, when the wavelength of the lithography machine is fixed, the larger the numerical aperture, the lower the resolution and the smaller the pattern size that can be imaged. The NA of the dry lithography machine is 0.93, and the NA of the immersion lithography machine is 1.35. The increase in NA is because water is added under the lens. The refractive index of water is 1.44, and 1.35 = 1.44 * 0.93. Therefore, the immersion lithography machine has an additional immersion hood compared to the dry lithography machine.

[0003] The traditional immersion hood includes an immersion head, a liquid supply device, and a waste liquid recovery device. The immersion head includes a liquid inlet and a liquid outlet. The liquid supply device is connected to the liquid inlet of the immersion head, and the waste liquid recovery device is connected to the liquid outlet of the immersion head. The immersion hood also includes a gas blowing and exhaust system, etc. Since the structure of the immersion hood is relatively complex, it is easily contaminated by impurities (particles) caused by process surface problems. The impurities include, for example, photoresist residues, film layer peeling on the wafer surface, or hair and dandruff, etc. These impurities will affect the exposure effect. Therefore, cleaning and maintaining the immersion hood has become an important issue for the lithography machine. The traditional cleaning method must use professional tools and stop the machine for cleaning. The cleaning time and the pirun time after restarting are approximately 8hr - 16hr, seriously affecting the Fab production capacity and efficiency. Summary of the Invention

[0004] One of the objectives of the present invention is to provide a method for using a standard wafer to clean an immersion hood of a lithography machine, which can effectively remove the impurities in the immersion hood, achieve the purpose of cleaning the immersion hood, and does not require stopping the machine, helping to improve the cleaning efficiency and reduce the impact of cleaning the immersion hood on the production capacity of the lithography machine.

[0005] To achieve the above objective, the method for using a standard wafer to clean an immersion hood of a lithography machine provided by the present invention includes: providing a standard wafer, the surface of the standard wafer having a groove pattern; and placing the standard wafer in the lithography machine for virtual exposure. During the virtual exposure process, the groove pattern catches the impurities in the immersion hood of the lithography machine to carry out the impurities out of the immersion hood.

[0006] Optionally, the groove pattern extends along a first direction; during the virtual exposure process, the standard wafer moves along a second direction, and the first direction is perpendicular to the second direction.

[0007] Optionally, the standard wafer has a plurality of groove patterns extending in different directions or has an annular groove pattern; during the virtual exposure process, the standard wafer moves freely along the first direction and / or the second direction, and the first direction is perpendicular to the second direction.

[0008] Optionally, when the width of the impurity is less than 1 μm, the groove depth of the groove pattern is greater than or equal to 1 μm and less than or equal to 10 μm; when the width of the impurity is greater than or equal to 1 μm, the groove depth of the groove pattern is greater than or equal to 10 μm and less than or equal to 100 μm.

[0009] Optionally, the groove pattern includes at least one of a strip-shaped groove, a circular hole-shaped groove, a corner-shaped groove, or an annular groove.

[0010] Optionally, the standard wafer includes a plurality of the groove patterns arranged at intervals, the width of each groove pattern is greater than or equal to 500 nm and less than or equal to 10 μm, and the distance between the groove patterns is greater than or equal to 500 nm and less than or equal to 10 μm.

[0011] Optionally, the distance from the groove pattern to the edge of the standard wafer is greater than or equal to 3 mm.

[0012] Optionally, the standard wafer has a plurality of annular steps arranged around the center of the standard wafer, the height of the plurality of annular steps gradually decreases from the inside to the outside, and the groove pattern is arranged between every two adjacent annular steps.

[0013] Optionally, the surface of the standard wafer has a water-repellent and oil-attracting adsorption coating, and the adsorption coating covers at least the groove pattern.

[0014] Optionally, the material of the adsorption coating includes carbon nanotubes and TiO2.

[0015] In the method for cleaning the immersion mask of a lithography machine using the standard wafer provided by the present invention, the surface of the provided standard wafer has a groove pattern. The standard wafer is placed in the lithography machine for virtual exposure. During the virtual exposure process, the groove pattern of the standard wafer catches the impurities in the immersion mask of the lithography machine to take the impurities out of the immersion mask, so that the impurities in the immersion mask can be effectively removed, the purpose of cleaning the immersion mask can be achieved, and there is no need to stop the machine, which helps to improve the cleaning efficiency and reduce the impact of cleaning the immersion mask on the production capacity of the lithography machine. Description of the Drawings

[0016] Figure 1Flow chart of a method for cleaning an immersion mask of a lithography machine using a standard wafer provided by an embodiment of the present invention.

[0017] Figures 2 to 10 Schematic plan view of different standard wafers provided by the present invention.

[0018] Figure 11 Three-dimensional schematic diagram of a standard wafer with steps provided by an embodiment of the present invention.

[0019] Figure 12 For Figure 11 Cross-sectional view of the standard wafer shown.

[0020] Explanation of reference numerals: 100 - standard wafer; 101 - groove pattern. Detailed description of the specific implementation

[0021] The following further elaborates on the method for cleaning an immersion mask of a lithography machine using a standard wafer proposed by the present invention in conjunction with the accompanying drawings and specific embodiments. According to the following description, the advantages and features of the present invention will be clearer. It should be noted that the accompanying drawings are all in a very simplified form and use non-precise scales, only for conveniently and clearly assisting in explaining the purpose of the embodiments of the present invention.

[0022] Figure 1 Flow chart of a method for cleaning an immersion mask of a lithography machine using a standard wafer provided by an embodiment of the present invention. As Figure 1 shown, the method for cleaning an immersion mask of a lithography machine using a standard wafer provided in this embodiment includes:

[0023] Step S1, provide a standard wafer, and the surface of the standard wafer has a groove pattern;

[0024] Step S2, place the standard wafer in the lithography machine for virtual exposure. During the virtual exposure process, the groove pattern on the standard wafer catches the impurities in the immersion mask to carry the impurities out of the immersion mask.

[0025] Figures 2 to 10 Schematic plan view of different standard wafers provided by the present invention. Referring to Figures 2 to 10 shown, the surface of the standard wafer 100 provided in step S1 has a groove pattern 101.

[0026] Exemplarily, the groove depth of the groove pattern 101 can be selected based on the size of the impurities in the immersion mask, so that the standard wafer 100 can effectively catch the impurities and improve the cleaning effect. Exemplarily, when the width of the impurities is less than 1 μm, the groove depth of the groove pattern 101 can be greater than or equal to 1 μm and less than or equal to 10 μm; when the width of the impurities is greater than or equal to 1 μm, the groove depth of the groove pattern is greater than or equal to 10 μm and less than or equal to 100 μm, but not limited thereto.

[0027] Exemplarily, the groove pattern 101 of the standard wafer 100 can be a strip-shaped groove (as shown in Figure 2 and Figure 3 ), a round-hole-shaped groove (as shown in Figure 4 ), a corner-shaped groove (as shown in Figure 5 ), or an annular groove (as shown in Figure 6 ), etc., and can also be a combination of these patterns.

[0028] When the groove pattern 101 is a strip-shaped groove, the strip-shaped groove can be a straight strip (as shown in Figure 2 , Figure 3 and Figure 7 ), or can be an arc-shaped strip (as shown in Figure 8 and Figure 9 ). The strip-shaped groove can be a long strip (as shown in Figure 2 , Figure 7 , Figure 8 and Figure 9 ), and can also be a short strip (as shown in Figure 3 ). As shown in Figure 7 , the strip-shaped groove can be a transverse strip extending along the first direction X; as shown in Figure 1 , the strip-shaped groove can also be a vertical strip extending along the second direction Y.

[0029] Since the long strip-shaped groove and the annular groove occupy a relatively large area on the wafer surface, when the standard wafer 100 moves, they have a better blocking effect on the movement of impurities in the immersion mask, can better trap the impurities, so the long strip-shaped groove and the annular groove can be preferably used as the groove pattern 101 of the standard wafer 100.

[0030] In an embodiment of the present application, as shown in Figure 10 , the surface of the standard wafer 100 can have a plurality of groove patterns 101 extending in different directions, for example, having a two-way strip-shaped groove, that is, having a groove pattern 101 of a transverse strip and a groove pattern 101 of a vertical strip at the same time. For example, with a diameter of the standard wafer 100 as the center line, the groove pattern of the transverse strip and the groove pattern of the vertical strip can be distributed on both sides of the diameter, but not limited thereto.

[0031] Figure 11 Three-dimensional schematic diagram of a standard wafer with steps provided by an embodiment of the present invention. Figure 12 is Figure 11 The cross-sectional view of the standard wafer shown. In an embodiment of the present application, referring to Figure 11 and Figure 12As shown, the standard wafer 100 may have a plurality of annular steps arranged around the center of the standard wafer. The heights of the plurality of annular steps gradually decrease from the inside to the outside. A groove pattern 101 is provided between every two adjacent annular steps. The groove pattern 101 is, for example, an annular groove. When using this standard wafer to remove impurities from the immersion mask, the steps with different heights can be used to bring the impurities into the groove pattern 101, which helps to improve the cleaning effect.

[0032] In some embodiments of the present application, the surface of the standard wafer 100 may have a water-repellent and oil-attracting adsorption coating. The adsorption coating covers at least the groove pattern 101. The adsorption coating can help the standard wafer 100 better adsorb impurities and improve the cleaning effect on the immersion mask. The adsorption coating can cover the entire surface of the standard wafer 100, so that the adsorption effect is better and the manufacturing process of the adsorption coating is relatively simple.

[0033] In some embodiments of the present application, the adsorption coating can also decompose the organic matter in the adsorbed impurities. The decomposed part of the impurities can be washed away by the water flow, which can further improve the removal effect of the impurities.

[0034] In this embodiment, the material of the adsorption coating includes carbon nanotubes and TiO2. Exemplarily, the adsorption coating may include a carbon nanotube layer formed on the surface of the standard wafer 100 and TiO2 attached to the carbon nanotube layer. The adsorption coating can also be a mixed material layer of carbon nanotubes and TiO2. Carbon nanotubes have strong adsorption properties and can adsorb impurities; the TiO2 material has water-repellent properties, and the TiO2 material can be used as a photocatalyst layer. The photocatalyst layer can decompose the organic pollutants attached to the surface, making them smaller or even completely decomposed. When water flows through the surface of TiO2, the decomposed organic matter in the impurities will be washed away, and if there are inorganic substances in the impurities that are not decomposed, they will remain in the groove pattern 101 and be clamped and taken out of the immersion mask by the groove pattern 101. Therefore, using this standard wafer 100 to regularly clean the immersion mask can reduce the accumulation of pollution. In other embodiments, the adsorption coating can also be made of other materials with water-repellent and oil-attracting properties.

[0035] Exemplarily, taking Figure 11 the standard wafer 100 shown as an example, the manufacturing method of the standard wafer 100 may include: grinding and thinning the wafer along the radius in multiple steps with different thicknesses to form a plurality of annular steps; defining the shape, width, and extension direction of the groove pattern 101; etching the wafer to form the groove pattern 101; depositing a water-repellent and oil-attracting adsorption coating on the wafer to form the standard wafer. Among them, the groove pattern 101 can be defined by photoresist, but it is not limited thereto.

[0036] Exemplarily, referring to Figure 2 and Figure 6As shown, the standard wafer 100 includes a plurality of the groove patterns 101 arranged at intervals. The width W of each groove pattern 101 can be greater than or equal to 500 nm and less than or equal to 10 μm, but is not limited thereto. In other embodiments, the width W of the groove pattern 101 can be adjusted according to the size of the impurities, the etching depth of the pattern, and the different chip production processes.

[0037] When the spacing between the groove patterns 101 is too large, the pattern density is low and the number of impurities that can be trapped is small. When the spacing between the patterns is too small and the depth is relatively deep, pattern collapse is likely to occur. Therefore, in this embodiment, the spacing D between the groove patterns 101 can be greater than or equal to 500 nm and less than or equal to 10 μm, which can balance the pattern density and avoid pattern collapse. In other embodiments, the spacing D between the groove patterns 101 can be adjusted according to the etching depth of the pattern and the different chip production processes. It should be noted that when setting the width, depth, and spacing of the groove patterns, the problem of pattern collapse needs to be avoided.

[0038] Exemplarily, the groove depths of the plurality of groove patterns 101 on the same standard wafer 100 can be equal, the groove widths can be equal, and the spacing between two adjacent groove patterns can also be equal, but is not limited thereto.

[0039] In this embodiment, the distance from the groove pattern 101 to the edge of the standard wafer 100 is greater than or equal to 3 mm, which can avoid defects in the patterns at the wafer edge during etching. In other embodiments, the distance from the groove pattern 101 to the edge of the standard wafer 100 can be adjusted according to the actual situation.

[0040] Perform step S2, place the standard wafer 100 in a lithography machine for virtual exposure. During the virtual exposure process, the groove pattern 101 of the standard wafer 100 traps the impurities in the immersion mask of the lithography machine to carry the impurities out of the immersion mask.

[0041] It should be noted that during the virtual exposure process, the standard wafer 100 is placed on the console of the lithography machine, and the console moves with the standard wafer 100. The surface of the standard wafer 100 with the groove pattern 101 faces the immersion mask. The water in the immersion mask can form a flowing water film between the standard wafer 100 and the lens. Thus, the impurities in the immersion mask can contact the standard wafer 100 driven by the water. Furthermore, the groove pattern 101 on the surface of the standard wafer 100 can trap the impurities in the immersion mask to carry the impurities out of the immersion mask, achieving the effect of cleaning the immersion mask. Among them, during the virtual exposure process, the lithography machine can irradiate light on the standard wafer 100 or not irradiate light on the standard wafer 100.

[0042] During virtual exposure, since the console carrying the wafer drives the standard wafer 100 to move, and the lithography machine console can only move along the first direction X or the second direction Y, the standard wafer 100 can only move along the first direction X or the second direction Y.

[0043] In an embodiment of the present application, the groove pattern 101 of the standard wafer 100 extends along the first direction X. During virtual exposure, the standard wafer 100 moves along the second direction Y perpendicular to the first direction X, or rather, the movement of the standard wafer 100 is mainly in the second direction Y. In this way, the movement direction of the standard wafer 100 during virtual exposure is perpendicular to the elongation direction of the groove pattern 101, which can keep impurities in the groove pattern 101 to the greatest extent and carry them out of the immersion mask, helping to improve the cleaning effect of the immersion mask. Similarly, when the groove pattern 101 extends along the second direction Y, during virtual exposure, the standard wafer 100 preferably moves along the first direction X.

[0044] In an embodiment of the present application, refer to Figure 10 As shown, the standard wafer 100 includes a two-way groove pattern of horizontal bars and vertical bars. During virtual exposure, the console can drive the standard wafer 100 to move freely along the first direction X and / or the second direction Y to clean the immersion mask, so that the flexibility of the movement of the standard wafer 100 is relatively high.

[0045] In an embodiment of the present application, refer to Figure 6 As shown, the standard wafer 100 has an annular groove pattern 101. During virtual exposure, the console can drive the standard wafer 100 to move freely along the first direction X and / or the second direction Y to clean the immersion mask.

[0046] In an embodiment of the present application, step S1 can provide multiple standard wafers 100. In step S2, multiple standard wafers 100 can be successively placed in the lithography machine for virtual exposure. Specifically, at least some of the groove patterns 101 of the standard wafers 100 are different from those of other standard wafers 100. Some standard wafers 100 can move along the first direction X during virtual exposure, and some standard wafers 100 can move along the second direction Y during virtual exposure. More specifically, the groove pattern 101 of the standard wafer 100 moving along the first direction X during virtual exposure can extend along the second direction Y or be annular or include horizontal bar grooves and vertical bar grooves; the groove pattern 101 of the standard wafer 100 moving along the second direction Y during virtual exposure can extend along the first direction X or be annular or include horizontal bar grooves and vertical bar grooves.

[0047] In this application, the standard wafer 100 can be recycled, that is, the standard wafer 100 that has been used to clean the immersion mask can be used again to clean the immersion mask after being washed. Exemplarily, the used standard wafer 100 can be rinsed with deionized water, dried and then rinsed with nitrogen. When the surface of the standard wafer 100 has an adsorption coating, the specification of the impurities adsorbed by the standard wafer can be determined according to the density of the adsorption coating, such as the number of times the standard wafer can be used, so as to improve the use efficiency of the standard wafer and reduce the cleaning cost.

[0048] In the method for cleaning the immersion mask of a lithography machine using a standard wafer provided by the present invention, the surface of the provided standard wafer 100 has a groove pattern 101. The standard wafer 100 is placed in the lithography machine for virtual exposure. During the virtual exposure process, the groove pattern 101 of the standard wafer catches the impurities in the immersion mask of the lithography machine to take the impurities out of the immersion mask, so that the impurities in the immersion mask can be effectively removed, the purpose of cleaning the immersion mask can be achieved, and there is no need to stop the machine, which helps to improve the cleaning efficiency and reduce the impact of cleaning the immersion mask on the production capacity of the lithography machine.

[0049] The above description is only a description of the preferred embodiments of the present invention, and does not limit the scope of the rights of the present invention in any way. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A method of using a standard wafer cleaning lithography immersion mask, characterized in that, Comprising: Providing a standard wafer, the surface of the standard wafer having a groove pattern; And Placing the standard wafer in a lithography machine for virtual exposure, during the virtual exposure process, the groove pattern catching impurities in the immersion mask of the lithography machine to carry out the impurities from the immersion mask.

2. The method of using an immersion mask for a standard wafer cleaning lithography machine according to claim 1, wherein The groove pattern extends along a first direction; during the virtual exposure process, the standard wafer moves along a second direction, the first direction and the second direction being perpendicular.

3. The method of using the immersion mask of the standard wafer cleaning lithography machine according to claim 1, wherein The standard wafer has a plurality of groove patterns extending in different directions or has an annular groove pattern; during the virtual exposure process, the standard wafer moves freely along the first direction and / or the second direction, the first direction and the second direction being perpendicular to each other.

4. The method of using the immersion mask of the standard wafer cleaning lithography machine according to claim 1, wherein, When the width of the impurity is less than 1 μm, the groove depth of the groove pattern is greater than or equal to 1 μm and less than or equal to 10 μm; when the width of the impurity is greater than or equal to 1 μm, the groove depth of the groove pattern is greater than or equal to 10 μm and less than or equal to 100 μm.

5. The method of using an immersion mask for a standard wafer cleaning lithography machine according to claim 1, characterized in that The groove pattern includes at least one of a strip groove, a round hole groove, a corner groove or an annular groove.

6. The method of using an immersion mask for a standard wafer cleaning lithography machine according to claim 1, wherein The standard wafer includes a plurality of the groove patterns arranged at intervals, the width of each groove pattern being greater than or equal to 500 nm and less than or equal to 10 μm, and the distance between the groove patterns being greater than or equal to 500 nm and less than or equal to 10 μm.

7. The method of using an immersion mask of a standard wafer cleaning lithography machine according to claim 1, characterized in that, The distance from the groove pattern to the edge of the standard wafer is greater than or equal to 3 mm.

8. The method of using an immersion mask of a standard wafer cleaning lithography machine according to claim 1, characterized in that The standard wafer has a plurality of annular steps arranged around the center of the standard wafer, the heights of the plurality of annular steps gradually decreasing from the inside out, and the groove pattern being provided between every two adjacent annular steps.

9. The method of using an immersion mask of a standard wafer cleaning lithography machine according to claim 1, wherein The surface of the standard wafer has a water-repellent and oil-attracting adsorption coating, the adsorption coating at least covering the groove pattern.

10. The method of using an immersion mask of a standard wafer cleaning lithography machine according to claim 9, characterized in that, The material of the adsorption coating includes carbon nanotubes and TiO2.

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