Method of cleaning a wafer table of a lithography machine and cleaning tool

Abstract

Disclosed are a cleaning method and a cleaning tool for a wafer table of a photolithography machine. The method comprises: a control module of the cleaning tool acquiring a position of a contaminant on a surface of the wafer table; a cleaning component of the cleaning tool being fixed on a wafer bearing table of the photolithography machine, the wafer table being located on the wafer bearing table, the cleaning component comprising a cleaning head, a dissolving head, a chemical reagent supply unit and a cleaning cover; the control module controlling the cleaning component to move to above the contaminant based on the position of the contaminant; the control module controlling the dissolving head to move downward until the dissolving head contacts the wafer table, and controlling the chemical reagent supply unit to inject a chemical reagent into the dissolving head for a preset time; the control module switching the dissolving head to the cleaning head, and controlling the cleaning head to perform a rotating cleaning operation to remove the contaminant; and during the injection of the chemical reagent and the rotating cleaning operation, the cleaning cover covers the dissolving head and the cleaning head to form a closed space to slow down evaporation of the chemical reagent. The embodiments of the present application can effectively remove the contaminant on the wafer table.

Description

Technical Field

[0001] This application relates to the field of semiconductor devices and integrated circuit technology, and in particular to a cleaning method and cleaning tool for a lithography machine wafer stage. Background Technology

[0002] In the photolithography process of semiconductor manufacturing, the wafer table of the lithography machine is used to support and fix the wafer. Its surface flatness directly affects the uniformity of focusing on the wafer surface during exposure, and can determine the stability of the product's critical dimension (CD) and overlay accuracy (OVL). With the increase in wafer size and the miniaturization of process nodes, the requirements for wafer table flatness in lithography machines are becoming increasingly stringent.

[0003] During the manufacturing process, the back side of wafers often carries sticky contaminants such as photoresist and resin polymers. When the wafer is adsorbed onto the wafer stage, these sticky substances transfer and accumulate on the stage surface, especially at the edges. This contaminant buildup causes localized bulges or depressions on the wafer stage, preventing the wafer from maintaining absolute flatness during exposure. This leads to quality issues such as misalignment of critical dimensions and overlay accuracy, and can even result in the scrapping of an entire batch of wafers, while also shortening the lifespan of the wafer stage.

[0004] Currently, the cleaning methods for lithography machine wafer stages mainly include automatic cleaning and manual cleaning. Automatic cleaning can only remove ordinary particulate matter and is basically ineffective against sticky substances such as photoresist and resin. Manual cleaning usually uses chemical reagents (such as isopropyl alcohol (IPA) and acetone) to dissolve contaminants before wiping them off. However, these chemical reagents are highly volatile, and the contact time with contaminants is too short to fully dissolve sticky substances. In addition, traditional manual cleaning often uses a linear reciprocating wiping method, which involves pauses during turning, resulting in discontinuous shear stress, high energy loss, and a low removal rate of sticky substances, leading to poor cleaning results. Therefore, there is an urgent need for a cleaning method that can effectively remove sticky contaminants from the wafer stage surface and restore its flatness. Summary of the Invention

[0005] This application provides a cleaning method and cleaning tool for a lithography machine wafer stage, which can solve the problems of low efficiency and poor effect of manually cleaning wafer stages in related technologies.

[0006] On one hand, embodiments of this application provide a cleaning method for a lithography machine wafer stage, including: The control module of the cleaning tool acquires the location of contaminants on the surface of the wafer stage. The cleaning component of the cleaning tool is fixed on the wafer carrier of the lithography machine. The wafer stage is located above the wafer carrier. The cleaning component includes a cleaning head, a dissolving head, a chemical reagent supply unit, and a cleaning hood. The control module controls the cleaning component to move above the contaminant based on the location of the contaminant. The control module controls the cleaning component to move downwards until the dissolving head contacts the wafer stage, and controls the chemical reagent supply unit to inject chemical reagent into the dissolving head for a preset time. The control module switches the dissolving head to the cleaning head and controls the cleaning head to perform a rotary cleaning operation to remove the contaminants; During the injection of chemical reagents and the rotating cleaning operation, the cleaning hood covers the dissolving head and the cleaning head to form a closed space to slow down the evaporation of the chemical reagents.

[0007] In some embodiments, the control module controls the chemical reagent supply unit to inject chemical reagents into the dissolving head, including: In the first phase, chemical reagents are injected into the dissolving head at a first unit injection dose for a first time. In the second stage, a chemical reagent is injected into the dissolving head at a second unit injection dose for a second duration, wherein the second unit injection dose is less than the first unit injection dose.

[0008] In some embodiments, the second time is longer than the first time.

[0009] In some embodiments, the chemical reagent includes isopropanol and / or acetone.

[0010] In some embodiments, controlling the cleaning head to perform a rotational cleaning operation includes: The cleaning head is controlled to perform a spiral cleaning operation within a designated area, which is determined based on the location of the contaminant and covers the entire location of the contaminant.

[0011] In some embodiments, controlling the cleaning head to perform a rotational cleaning operation includes: A preset pressure is applied to the cleaning head, and the cleaning head is controlled to rotate at a preset speed of more than 1080 degrees, using the continuous shear stress generated by the rotation to peel off the contaminants.

[0012] In some embodiments, the preset rotation speed is 100 to 200 revolutions per minute.

[0013] In some embodiments, the preset pressure is 1.5 Newtons to 2 Newtons.

[0014] On the other hand, embodiments of this application provide a cleaning tool for cleaning a lithography machine wafer stage, the cleaning tool comprising: Base; The slide rail includes a first slide rail and two second slide rails. The second slide rails are fixed to the base. From a top view, the two second slide rails are parallel to each other. The first slide rail and the second slide rails are perpendicular to each other. When the cleaning tool is working, the first slide rail slides along the second slide rail. A cleaning structure is provided, which is disposed on the first slide rail and slides along the first slide rail when the cleaning tool is working. A chemical reagent supply unit is provided on the cleaning structure, which stores chemical reagents. A conduit is formed in the cleaning structure. One side of the conduit extends from the cleaning mechanism away from the first slide rail to its port. A dissolving head and a cleaning head are provided at the port. The other side of the conduit is connected to the chemical reagent supply unit. A cleaning hood is disposed in the area from which the conduit extends; A control module is provided for controlling the cleaning tool to perform the cleaning method for the lithography wafer stage as described above.

[0015] The technical solution of this application has at least the following advantages: By fixing the cleaning tool to the wafer carrier stage, locating the contaminant on the wafer stage, controlling the dissolving head to contact the area of ​​the contaminant and injecting chemical agents, and then switching to the cleaning head to treat the contaminant by rotation, the cleaning method can remove the contaminant more thoroughly than linear cleaning. At the same time, because the cleaning hood can prevent the chemical reagents from evaporating, it can more effectively remove contaminants on the wafer stage and improve the flatness of the wafer stage during operation. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 This is a perspective view of a cleaning tool provided in an exemplary embodiment of this application; Figure 2 This is a side view of a cleaning tool provided in an exemplary embodiment of this application; Figure 3This is a flowchart of a cleaning method for a lithography machine wafer stage provided in an exemplary embodiment of this application; Figure 4 This is a schematic diagram of a cleaning method for a lithography machine wafer stage provided in an exemplary embodiment of this application, which employs a rotary cleaning operation. Figure 5 This is a schematic diagram of a spiral cleaning operation used in a cleaning method for a lithography machine wafer stage provided in an exemplary embodiment of this application. Detailed Implementation

[0018] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0019] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0020] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0021] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0022] refer to Figure 1 It shows a perspective view of a cleaning tool provided in an exemplary embodiment of this application; Reference Figure 2 This illustrates a side view of a cleaning tool provided in an exemplary embodiment of this application. For example, as shown... Figure 1 and Figure 2As shown, this cleaning tool is used to clean the wafer stage of a lithography machine. The cleaning tool includes: Base 200. (As shown) Figure 1 ( Figure 2 As shown in the figure (not shown, base 200), the base 200 can be a frame for supporting the cleaning component of the cleaning tool. When the cleaning tool is working, the lithography machine can be placed in the frame so that the cleaning component is fixed above the wafer carrier stage 110.

[0023] The slide rail includes a first slide rail 211 and two second slide rails 212, which are fixed to the base 200. Viewed from above, the two second slide rails 212 are parallel to each other (i.e., their sliding directions are parallel), and the first slide rail 211 and the second slide rails 212 are perpendicular (i.e., their sliding directions are perpendicular). When the cleaning tool is in operation, the first slide rail 211 slides along the second slide rails 212.

[0024] For example, such as Figure 1 ( Figure 2 As shown in the figure (not shown), the first slide rail 211 and the second slide rail 212 are cubes. The direction of the length of the first slide rail 211 can be defined as the y-axis, and the direction of the length of the second slide rail 212 can be defined as the x-axis, thus realizing the movement of the first slide rail 211 in the x-axis direction.

[0025] A cleaning structure 220 is mounted on a first slide rail 211 and slides along the first slide rail 211 when the cleaning tool is in operation. A chemical reagent supply unit 230 is provided on the cleaning structure 220, storing chemical reagents. A conduit 221 is formed within the cleaning structure 220, with one side of the conduit 221 extending from the cleaning mechanism 220 away from the first slide rail 221 to its port. A dissolving head and a cleaning head are provided at the port. Figure 2 The dissolving head 2221 is provided as an example at the port (the cleaning head is not shown). The other side of the conduit 221 is connected to the chemical reagent supply unit 230.

[0026] For example, such as Figure 2 As shown, since the cleaning structure 220 can slide along the first slide rail 211 and the first slide rail 211 can slide along the second slide rail 212, the cleaning structure 220 can move in the x-axis and y-axis directions.

[0027] The chemical reagent supply unit 230 can be equipped with multiple storage tanks to store different chemical reagents, for example, Figure 2In the chemical supply unit 230, there are a first storage tank 231 and a second storage tank 232. The first storage tank 231 stores isopropanol and the second storage tank 232 stores acetone. Chemical reagents can be supplied to the conduit 221 as needed.

[0028] The cleaning structure 220 is provided with a third slide rail 224 and a slider 223. The slider 223 is fixedly connected to the cleaning structure 220 and slidably connected to the third slide rail 224. The sliding direction of the third slide rail 224 is perpendicular to the sliding direction of the first slide rail 211, and the sliding direction of the third slide rail 224 is perpendicular to the plane containing the sliding directions of the first slide rail 211 and the second slide rail 212, thereby realizing the movement of the cleaning structure 220 in the z-axis direction.

[0029] The cleaning structure 220 is also provided with a limit block 225 to prevent the cleaning structure 220 from moving too downward and causing damage to the wafer stage 120. The cleaning structure 220 is also provided with at least one counterweight 226 to apply pressure to the wafer stage 120 by the cleaning head when the cleaning tool is working.

[0030] A cleaning hood 222 is provided in the area from which the conduit 221 extends.

[0031] Control module ( Figure 1 and Figure 2 (not shown in the image), which is used to control the cleaning tool to perform the cleaning method of the lithography wafer stage in any of the following embodiments.

[0032] refer to Figure 3 The diagram illustrates a flowchart of a cleaning method for a lithography machine wafer stage provided in an exemplary embodiment of this application. This method can be performed by… Figure 1 The cleaning tool in the embodiment performs the method, which includes: Step S1: The control module of the cleaning tool obtains the location of contaminants on the surface of the wafer stage. The cleaning component of the cleaning tool is fixed on the wafer carrier of the lithography machine. The wafer stage is located on the wafer carrier. The cleaning component includes a cleaning head, a dissolving head, a chemical reagent supply unit, and a cleaning hood.

[0033] For example, the control module can establish the same coordinate system with the lithography machine, obtain the contaminant test results of the lithography machine's wafer stage, and determine the contaminant position based on the test results. The method by which the control module obtains the contaminant position on the wafer stage surface is not limited to the above method, but can also be obtained according to other existing technologies.

[0034] In step S2, the control module controls the cleaning component to move above the contaminant based on the contaminant's location.

[0035] For example, after obtaining the location of the contaminant, the control module can control the sliders on the first and second slide rails to move the cleaning component in the xy plane until it is above the contaminant.

[0036] In step S3, the control module controls the cleaning component to move downwards until the dissolving head contacts the wafer stage, and controls the chemical reagent supply unit to inject chemical reagent into the dissolving head for a preset time.

[0037] For example, the control module can control the slider in the cleaning structure to move the cleaning component downward along the z-axis until the dissolving head contacts the wafer stage, and control the chemical reagent supply unit to inject chemical reagent into the dissolving head for a preset time. During the injection of chemical reagent, the cleaning hood covers the dissolving head to form a closed space to slow down the evaporation of chemical reagent.

[0038] The chemical reagent injection process comprises two stages: In the first stage, a first unit dose of chemical reagent is injected into the dissolving head for a first duration to wet the dissolving head; in the second stage, a second unit dose of chemical reagent is injected into the dissolving head for a second duration to continuously dissolve the reagent. The second unit dose is less than the first unit dose, and the second duration is longer than the first duration. For example, the first unit dose can be from 10 mL / min to 30 mL / min, the second unit dose can be from 0.05 mL / min to 0.3 mL / min, the first duration can be from 1 second to 5 seconds, and the second duration can be from 1 minute to 7 minutes.

[0039] For oily and organic pollutants, isopropanol can be used for cleaning, while for light-blocking and organic pollutants, acetone can be used for cleaning. Both isopropanol and acetone are volatile chemical reagents, and by installing a cleaning cover, the premature evaporation of the chemical reagents can be prevented.

[0040] In step S4, the control module switches the dissolving head to the cleaning head and controls the cleaning head to perform a rotating cleaning operation to remove contaminants.

[0041] In related technologies, the linear wiping method used for cleaning contaminants manually is not very effective for removing sticky contaminants. Practical experience has shown that the rotary cleaning method (especially rotation of 1080 degrees or more) is significantly more effective at cleaning contaminants.

[0042] During the rotary cleaning operation, the cleaning tool continuously and quantitatively adds chemical reagents (isoacetone and / or acetone) to the dissolving head. The dissolving time can be controlled according to the dissolving effect. During the rotary cleaning operation, the cleaning hood covers the cleaning head to form a closed space to slow down the evaporation of chemical reagents. By controlling the cleaning head to perform the rotary cleaning operation, sticky contaminants on the wafer stage can be effectively removed, and the flatness of the wafer stage can be improved.

[0043] For the same contaminant, cleaning effectiveness is positively correlated with shear stress. Rotary cleaning is continuous, while linear reciprocating cleaning involves pauses during turning, resulting in energy loss due to these pauses. The removal rates of different cleaning methods are as follows: Rotary circulation clearance rate: R _Spin= k · τ · S · v _Spin· t Linear reciprocating clearance rate: R _line= k · τ · S · v _Wire· t · β in: k This is a proportionality coefficient (related to the characteristics of contaminants, cleaning head material, etc.). τ • For shear stress, S • This refers to the contact area of ​​the cleaning head. v _Spin is the linear velocity of the rotating edge. v The line represents the linear cleaning speed. t For cleaning time, β This is the pause coefficient (the percentage of effective shearing time).

[0044] The difference between the rotary circulation clearance rate and the linear reciprocating clearance rate is as follows: R _Spin / R _line=1 / β ≈1.3 in, β The theoretical value is 0.77. With the same line-taking speed, the cleaning rate can be increased by at least 30% by using a rotation cleaning method.

[0045] Optionally, in step S4, the rotary cleaning operation can be performed in two ways: (1) Apply a preset pressure to the cleaning head and control the cleaning head to rotate at a preset speed of more than 1080 degrees, using the continuous shear stress generated by the rotation to peel off the contaminants. The rotary cleaning operation is as follows: Figure 4 As shown by the thick arrow; (2) Apply a preset pressure to the cleaning head and control the cleaning head to perform a spiral cleaning operation at a preset speed within a designated area. The designated area is determined based on the location of the contaminant and covers the entire contaminant location. The spiral cleaning operation is as follows: Figure 5 As indicated by the medium-thick arrow.

[0046] Optionally, in this embodiment, the cleaning head is made of polyethylene terephthalate (PET) fiber with a radius of 1.5 cm to 4 cm; the preset rotation speed of the cleaning head is 100 rpm to 200 rpm; the preset pressure is 1.5 N to 2 N; and the cleaning time is 1 second to 3 seconds per cleaning cycle.

[0047] In summary, in this embodiment, by fixing the cleaning tool to the wafer carrier stage, locating the contaminant on the wafer stage, controlling the dissolving head to contact the area where the contaminant is located and injecting chemical agents, the cleaning head is switched to a rotating manner to treat the contaminant. Since the rotating cleaning method can remove contaminants more thoroughly than the linear cleaning method, and since the cleaning hood can prevent the chemical agents from evaporating, it can more effectively remove contaminants on the wafer stage and improve the flatness of the wafer stage during operation.

[0048] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this application.

Claims

1. A method for cleaning a lithography machine wafer stage, characterized in that, include: The control module of the cleaning tool acquires the location of contaminants on the surface of the wafer stage. The cleaning component of the cleaning tool is fixed on the wafer carrier of the lithography machine. The wafer stage is located above the wafer carrier. The cleaning component includes a cleaning head, a dissolving head, a chemical reagent supply unit, and a cleaning hood. The control module controls the cleaning component to move above the contaminant based on the location of the contaminant. The control module controls the cleaning component to move downwards until the dissolving head contacts the wafer stage, and controls the chemical reagent supply unit to inject chemical reagent into the dissolving head for a preset time. The control module switches the dissolving head to the cleaning head and controls the cleaning head to perform a rotary cleaning operation to remove the contaminants; During the injection of chemical reagents and the rotating cleaning operation, the cleaning hood covers the dissolving head and the cleaning head to form a closed space to slow down the evaporation of the chemical reagents.

2. The method according to claim 1, characterized in that, The control module controls the chemical reagent supply unit to inject chemical reagents into the dissolving head, including: In the first phase, chemical reagents are injected into the dissolving head at a first unit injection dose for a first time. In the second stage, a chemical reagent is injected into the dissolving head at a second unit injection dose for a second duration, wherein the second unit injection dose is less than the first unit injection dose.

3. The method according to claim 2, characterized in that, The second time is longer than the first time.

4. The method according to any one of claims 1 to 3, characterized in that, The chemical reagents include isopropanol and / or acetone.

5. The method according to claim 4, characterized in that, The control of the cleaning head to perform a rotation cleaning operation includes: The cleaning head is controlled to perform a spiral cleaning operation within a designated area, which is determined based on the location of the contaminant and covers the entire location of the contaminant.

6. The method according to claim 4, characterized in that, The control of the cleaning head to perform a rotation cleaning operation includes: A preset pressure is applied to the cleaning head, and the cleaning head is controlled to rotate at a preset speed of more than 1080 degrees, using the continuous shear stress generated by the rotation to peel off the contaminants.

7. The method according to claim 6, characterized in that, The preset rotation speed is 100 to 200 revolutions per minute.

8. The method according to claim 7, characterized in that, The preset pressure is 1.5 Newtons to 2 Newtons.

9. A cleaning tool, characterized in that, The cleaning tool is used to clean the wafer stage of the lithography machine. The cleaning tool includes: Base; The slide rail includes a first slide rail and two second slide rails. The second slide rails are fixed to the base. When viewed from a top angle, the two second slide rails are parallel to each other. The first slide rail and the second slide rails are perpendicular to each other. When the cleaning tool is working, the first slide rail slides along the second slide rail. A cleaning structure is provided, which is disposed on the first slide rail and slides along the first slide rail when the cleaning tool is working. A chemical reagent supply unit is provided on the cleaning structure, which stores chemical reagents. A conduit is formed in the cleaning structure. One side of the conduit extends from the cleaning mechanism away from the first slide rail to its port. A dissolving head and a cleaning head are provided at the port. The other side of the conduit is connected to the chemical reagent supply unit. A cleaning hood is disposed in the area from which the conduit extends; A control module is provided for controlling the cleaning tool to perform the cleaning method for the lithography wafer stage as described in claim 1.

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