阅读说明：本技术 光刻设备中的物体 (Object in a lithographic apparatus ) 是由 A·尼基帕罗夫 J·F·M·贝克尔斯 于 2019-09-25 设计创作，主要内容包括：本发明涉及一种物体,诸如用于浸没式光刻设备的传感器,所述物体具有与浸没液体接触的外层,并且其中,所述外层具有包括稀土元素的成分。本发明还涉及包括这样的物体的浸没式光刻设备和用于制造这样的物体的方法。(The present invention relates to an object, such as a sensor for an immersion lithographic apparatus, having an outer layer in contact with an immersion liquid, and wherein the outer layer has a composition comprising a rare earth element. The invention also relates to an immersion lithographic apparatus comprising such an object and to a method for manufacturing such an object.)

1. An immersion lithographic apparatus comprising:

an object, the object comprising:

a substrate and an outer layer, the outer layer being in contact with an immersion liquid in use,

wherein the outer layer has a composition including a rare earth element.

2. The immersion lithographic apparatus according to claim 1, wherein the composition further comprises an inorganic and/or silicone polymer.

3. The immersion lithographic apparatus according to claim 2, wherein the polymer has a Si-O-Si-O backbone.

4. An immersion lithographic apparatus according to claim 2, wherein the polymer has one or more groups selected from methyl, ethyl, propyl, phenyl, vinyl.

5. An immersion lithographic apparatus according to claim 1 or 2, wherein the rare earth element is at least partially oxidised, nitrided, boronated, carbonised or silicified.

6. The immersion lithographic apparatus according to claim 1 or 2, wherein the object further comprises an intermediate layer between the substrate and the outer layer.

7. The immersion lithographic apparatus according to claim 7, wherein the intermediate layer comprises one or more of SiO2, SiO 2-x.

8. The immersion lithographic apparatus according to claim 1 or 2, wherein the outer layer has a concentration gradient of the rare earth element over the layer thickness that increases with increasing distance from the substrate.

9. The immersion lithographic apparatus according to claim 1 or 2, wherein the rare earth element is present in the outer surface of the outer layer in a concentration (atomic%) of 0.1 to 50 atomic%.

10. The immersion lithographic apparatus according to claim 1 or 2, wherein the object comprises at least one patterned layer comprising a pattern of through holes formed on the substrate and/or a pattern of steps formed in the through holes, and wherein the outer layer is formed on at least a part of the patterned layer.

11. The immersion lithographic apparatus according to any one of claims 1 to 14, wherein the object further comprises a radiation blocking layer formed on the substrate below the outer layer.

12. The immersion lithographic apparatus according to claim 11, wherein the radiation blocking layer comprises TiN.

13. An immersion lithographic apparatus according to claim 1 or 2, wherein the outer layer is transmissive for deep ultraviolet radiation, wherein the transmittance of the outer layer is at least 50%.

14. The immersion lithographic apparatus according to any one of claims 1 to 13, wherein the object is a sensor.

15. An immersion lithographic apparatus according to claim 1 or 2, wherein the rare earth element is one or more elements selected from the group comprising cerium (Ce), lanthanum (La), yttrium (Y), dysprosium (Dy), erbium (Er), holmium (Ho), samarium (Sm), thulium (Tm).

16. An object for a lithographic apparatus, comprising:

a substrate and an outer layer, wherein

A receding contact angle of water with the outer layer of at least 75 °; and is

The outer layer has a composition including a rare earth element.

17. A method of coating a substrate comprising:

providing a substrate;

depositing an outer layer having a composition including a rare earth element on the substrate by at least one of:

(a) sputtering, wherein at least one of the sputter target materials comprises a rare earth element, and

(b) PVD and/or CVD and/or ALD wherein at least one of the precursors/reactive gases includes a rare earth element, and

(c) plasma-initiated (co) polymerization, and

(d) ion implantation, wherein the ion source is a metal vapor arc source and the vapor comprises, at least in part, rare earths.

18. The method of claim 28, wherein the depositing of the composition comprising a rare earth element is performed before or alternating with the depositing of (a) an inorganic/organosilicon polymer or (b) any of SiO2 or SiO2-x, such that the composition comprises the polymer or SiO 2.

19. A method of coating a substrate comprising:

providing a substrate;

exposing the substrate to an oxidizing atmosphere comprising a compound of a rare earth element in volatile form and an inorganic/organosilicon polymer precursor, thereby depositing an outer layer on the substrate, the outer layer comprising a copolymerized and/or covalently bonded inorganic monomer and rare earth element.

Technical Field

The present invention relates to an object in a lithographic apparatus, wherein the object has a layer applied to the object. The invention relates in particular to a sensor mark for a sensor of a lithographic apparatus and a method of manufacturing a device using a lithographic apparatus.

Background

A lithographic apparatus is a machine that is configured to apply a desired pattern onto a substrate. For example, lithographic apparatus can be used in the manufacture of Integrated Circuits (ICs). A lithographic apparatus may, for example, project a pattern (also often referred to as a "design layout" or "design") of a patterning device (e.g., a mask) onto a layer of radiation-sensitive material (resist) that is disposed on a substrate (e.g., a wafer).

To project a pattern onto a substrate, a lithographic apparatus may use electromagnetic radiation. The wavelength of this radiation determines the minimum size of features patterned on the substrate. Typical wavelengths currently used are 365nm (i-line), 248nm, 193nm and 13.5 nm. A lithographic apparatus using Extreme Ultraviolet (EUV) radiation (having a wavelength in the range 4nm to 20nm, for example 6.7nm or 13.5nm) may be used to form smaller features on a substrate than a lithographic apparatus using radiation having a wavelength of 193nm, for example.

In an immersion lithographic apparatus, liquid is confined to an immersion space by a liquid confinement structure. The immersion space is between the final optical element of the projection system, through which the pattern is imaged, and the substrate, onto which the pattern is transferred, or the substrate table, on which the substrate is held. The liquid may be confined to the immersion space by a liquid seal. The liquid confinement structure may generate or use a gas flow, for example to help control the flow and/or position of liquid in the immersion space. The gas flow may help form a seal to pass liquid to the immersion space. At least a portion of the substrate support table is coated with a coating having limited hydrophilicity to reduce liquid loss due to movement of the substrate support table relative to the final optical element. At least a portion of the sensor integrated into the substrate support table is coated with a coating having limited hydrophilicity to reduce liquid loss and to reduce thermal load by keeping liquid evaporated.

Immersion lithographic apparatus rely on several sensors integrated into a support table that supports the substrate. These sensors are used to:

-substrate/support table alignment with respect to the reference frame;

lens (re) adjustment, setting, heating compensation; and

reticle (mask) heating compensation.

The sensor's label is integrated into a stack of thin film layers, which is deposited on a transparent (quartz) plate built into the support table and serves as:

spatial transmission filters for DUV (integrated lens interferometer at scanner "ILIAS" sensor, parallel ILIAS sensor (part), transmission image sensor "TIS" sensor function).

Spatial reflection filters for visible radiation "VIS", near infrared "NIR", mid infrared "MIR" (smart alignment sensor hybrid "SMASH" sensor function)

The reflection from the top surface (unmarked areas) of the stack is used for the level sensor.

For example, an upper hydrophobic layer (e.g., a layer with limited hydrophilicity) suffers from degradation due to exposure to deep ultraviolet radiation.

A hydrophobic layer (e.g. a layer with limited hydrophilicity) is applied to other objects in the lithographic apparatus. In practice, many objects in a lithographic apparatus have a coating or layer applied thereto. It may be difficult to prevent the coating or layer from deteriorating.

Degradation of the coating or layer is undesirable for a number of reasons, including undesirably generated particles that may introduce imaging errors if found into the beam path used to image the substrate or into the sensor, and the fact that: once the coating or layer degrades, the properties desired due to the presence of the coating or layer (e.g., a hydrophobic coating or layer) are no longer present.

Disclosure of Invention

It is desirable to provide an outer layer (e.g. a coating) for an object in a lithographic apparatus with improved resistance to degradation, for example to provide an improved hydrophobic (e.g. limited hydrophilic) coating for sensor markings with resistance to degradation.

According to an aspect, there is provided an immersion lithographic apparatus comprising: an object, the object comprising: a substrate and an outer layer, the outer layer being in contact with the immersion liquid in use, wherein the outer layer has a composition comprising a rare earth element.

According to an aspect, there is provided an object for a lithographic apparatus, the object comprising: a substrate and an outer layer, wherein water has a receding contact angle of at least 75 ° with the outer layer; and wherein the outer layer has a composition including a rare earth element.

According to an aspect, there is provided a method of coating a substrate, the method comprising; providing a substrate; depositing an outer layer having a composition comprising a rare earth element on the substrate by at least one of (a) sputtering in which at least one sputter target material comprises a rare earth element, and (b) PVD and/or CVD and/or ALD in which at least one of the precursors/reactive gases comprises a rare earth element, and (c) plasma-initiated (co) polymerization, and (d) ion implantation in which the ion source is a metal vapor arc source and the vapor at least partially comprises a rare earth element.

According to an aspect, there is provided a method of coating a substrate, the method comprising; providing a substrate; exposing the substrate to an oxidizing atmosphere comprising an inorganic/organosilicon polymer precursor and a compound of a rare earth element in volatile form, thereby depositing an outer layer on the substrate, the outer layer comprising a copolymerized and/or covalently bonded inorganic monomer and rare earth element.

Drawings

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which:

FIG. 1 schematically depicts a lithographic apparatus;

FIG. 2 schematically depicts a liquid confinement structure for use in a lithographic apparatus;

FIG. 3 is a cross-sectional view of a conventional transmissive sensor flag;

FIG. 4 is a cross-sectional view of a conventional reflective sensor flag;

FIG. 5 shows the sensor flag of FIGS. 3 and 4 in a single quartz plate;

fig. 6 illustrates the structure of a Lipocer;

fig. 7 illustrates the structure of a Lipocer as modified in the present invention;

FIG. 8 is a graph showing the advancing water contact angle of rare earth element oxides;

FIG. 9 is a schematic representation of SiO₂The structure of (1); and

FIG. 10 illustrates SiO as modified in the present invention₂The structure of (1).

Detailed Description

Herein, the terms "radiation" and "beam" are used to encompass all types of electromagnetic radiation, including ultraviolet radiation (e.g. having a wavelength of 365nm, 248nm, 193nm, 157nm or 126 nm).

The terms "reticle," "mask," or "patterning device" as used herein may be broadly interpreted as referring to a general purpose patterning device that can be used to impart an incident radiation beam with a patterned cross-section corresponding to a pattern to be created in a target portion of the substrate. In this context, the term "light valve" may also be used. Examples of other such patterning devices, in addition to classical masks (transmissive or reflective, binary, phase-shifting, hybrid, etc.), include programmable mirror arrays and programmable LCD arrays.

FIG. 1 schematically depicts a lithographic apparatus according to an embodiment. The apparatus comprises:

optionally, an illumination system (illuminator) IL configured to condition a radiation beam B (e.g. UV radiation or DUV radiation);

a support structure (e.g. a mask table) MT constructed to support a patterning device (e.g. a mask) MA and connected to a first positioner PM configured to accurately position the patterning device MA in accordance with certain parameters;

a support table, e.g. a sensor table for supporting one or more sensors or a substrate or wafer table WT constructed to hold a substrate (e.g. a resist-coated production substrate) W, connected to a second positioner PW configured to accurately position the surface of the table (e.g. of the substrate W) in accordance with certain parameters; and

a projection system (e.g. a refractive projection lens system) PS configured to project a pattern imparted to the radiation beam B by patterning device MA onto a target portion C (e.g. comprising part of, one or more dies) of the substrate W.

The lithographic apparatus may also be of a type including: wherein at least a portion of the substrate W may be covered by an immersion liquid having a relatively high refractive index, e.g. water, such as ultra-pure water (UPW), so as to fill an immersion space between the projection system PS and the substrate W. Immersion liquids may also be applied to other spaces in the lithographic apparatus, for example, between the patterning device MA and the projection system PS. Immersion techniques can be used to increase the numerical aperture of projection systems. The term "immersion" as used herein does not mean that a structure such as the substrate W must be submerged in a liquid; in contrast, "immersion" means only that liquid is located between the projection system PS and the substrate W during exposure. The path of the patterned beam of radiation from the projection system PS to the substrate W passes entirely through the immersion liquid. In an arrangement for providing immersion liquid between the final optical element of the projection system PS and the substrate W, the liquid confinement structure extends along at least a portion of a boundary of the immersion space between the final optical element of the projection system PS and a facing surface of the stage or table that faces the projection system PS.

In operation, the illuminator IL receives a radiation beam from a radiation source SO, for example, through a beam delivery system BD. The illumination system IL may include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic and/or other types of optical components, or any combination thereof, for directing, shaping, and/or controlling radiation. The illuminator IL may be used to condition the radiation beam B to have a desired spatial and angular intensity distribution in its cross-section at the plane of the patterning device MA.

The term "projection system" PS as used herein should be broadly interpreted as encompassing any type of projection system, including refractive, reflective, catadioptric, anamorphic, magnetic, electromagnetic and/or electrostatic optical systems, or any combination thereof, as appropriate for the exposure radiation being used, and/or for other factors such as the use of an immersion liquid or the use of a vacuum. Any use of the term "projection lens" herein may be considered as synonymous with the more general term "projection system".

The lithographic apparatus may be of a type having two or more support tables, e.g., two or more support tables, or a combination of one or more support tables and one or more support table cleaning, sensor or measurement tables. For example, a lithographic apparatus is a multi-stage apparatus that includes two or more tables on the exposure side of the projection system, each table including and/or holding one or more objects. In an example, one or more tables can hold a radiation-sensitive substrate. In an example, one or more tables may hold sensors for measuring radiation from the projection system. In an example, a multi-stage apparatus includes a first stage configured to hold a radiation sensitive substrate (i.e., a support stage) and a second stage (referred to below and generally without limitation as a measurement stage, a sensor stage, and/or a cleaning stage) that is not configured to hold a radiation sensitive substrate. The second stage may include and/or may hold one or more objects in addition to the radiation sensitive substrate. Such one or more objects may include one or more selected from: a sensor for measuring radiation from the projection system, one or more alignment marks and/or a cleaning device (for cleaning, for example, a liquid confinement structure).

In operation, the radiation beam B is incident on the pattern (layout) present on the patterning device (e.g. mask) MA, which is held on the support structure (e.g. mask table) MT, and is patterned by the patterning device MA. Having traversed the patterning device MA, the radiation beam B passes through the projection system PS, which focuses the beam onto a target portion C of the substrate W. With the aid of the second positioner PW and position sensor IF (e.g. an interferometric device, linear encoder, 2D encoder or capacitive sensor), the substrate table WT can be moved accurately, e.g. so as to position different target portions C in the path of the radiation beam B in focus and alignment. Similarly, the first positioner PM and another position sensor (which is not explicitly depicted in fig. 1) can be used to accurately position the patterning device MA with respect to the path of the radiation beam B. Patterning device MA and substrate W may be aligned using patterning device alignment marks M1, M2 and substrate alignment marks Pl, P2. Although the substrate alignment marks as illustrated occupy dedicated target portions, they may be located in spaces between a plurality of target portions C (these are known as scribe-lane alignment marks).

The controller 500 controls the overall operation of the lithographic apparatus and in particular performs the operational procedures described further below. The controller 500 may be embodied as a suitably programmed general purpose computer including a central processing unit, volatile and non-volatile memory devices, one or more input and output devices (such as a keyboard or screen), one or more network connections, and one or more interfaces to various parts of the lithographic apparatus. It will be appreciated that a one-to-one relationship between the control computer and the lithographic apparatus is not necessary. One computer may control a plurality of lithographic apparatuses. Multiple network computers may be used to control a lithographic apparatus. The controller 500 can also be configured to control one or more associated process devices and substrate processing devices in a lithographic cell or cluster of which the lithographic apparatus forms a part. The controller 500 may also be configured to be subordinate to the supervisory control system of the lithography unit or cluster and/or the overall control system of the factory. In arrangements of immersion systems that have been proposed for localization, the liquid confinement structure 12 extends along at least a part of a boundary of the immersion space 10 between the final optical element 100 of the projection system PS and a facing surface of the stage or table facing the projection system PS. The facing surface of the table is so-called because the table moves and is rarely stationary during use. Typically, the facing surface of the table is a surface of the substrate W, the support table WT (e.g., a substrate table that surrounds the substrate W), or both. Such an arrangement is illustrated in fig. 2. The arrangement illustrated in fig. 2 and described below may be applied to the lithographic apparatus described above and illustrated in fig. 1.

Fig. 2 schematically depicts a liquid confinement structure 12. The liquid confinement structure 12 extends along at least a portion of a boundary of the immersion space 10 between the final optical element 100 of the projection system PS and the support table WT or the substrate W. In an embodiment, a seal is formed between the liquid confinement structure 12 and the surface of the substrate W/support table WT. The seal may be ｃA non-contact seal such as ｃA gas seal 16 (such ｃA system with ｃA gas seal is disclosed in european patent application publication No. EP- ｃA-1,420,298) or ｃA liquid seal.

The liquid confinement structure 12 is configured to supply and confine immersion fluid (e.g., liquid) to the immersion space 10. Immersion fluid is introduced into the immersion space 10 through one of the liquid openings (e.g., opening 13 a). Immersion fluid may be removed through one of the liquid openings (e.g., opening 13 b). Immersion fluid may be brought into the immersion space 10 through at least two of the liquid openings (e.g., opening 13a and opening 13 b). Which of the liquid openings is used for supplying immersion liquid and optionally which is used for removing immersion liquid may depend on the direction of motion of the support table WT.

Immersion fluid may be contained in the immersion space 10 by a gas seal 16, the gas seal 16 being formed during use between the bottom of the liquid confinement structure 12 and a facing surface of the table (i.e. the surface of the substrate W and/or the surface of the support table WT). The gas in the gas seal 16 is supplied under pressure to the gap between the liquid confinement structure 12 and the substrate W and/or the support table WT via a gas inlet 15. Gas is extracted via a channel associated with the gas outlet 14. The excess pressure on the gas inlet 15, the vacuum level on the gas outlet 14 and the geometry of the gap are arranged such that there is a high velocity gas flow that confines the immersion fluid inwards. The force of the gas acting on the immersion fluid between the liquid confinement structure 12 and the substrate W and/or the support table WT confines the immersion fluid in the immersion space 10. A meniscus 320 is formed at the boundary of the immersion fluid. Such a system is disclosed in U.S. patent application publication No. US 2004-0207824. Other liquid confinement structures 12 may be used with embodiments of the invention.

The surfaces of many objects of a lithographic apparatus have a coating or layer applied thereto. The coating may have one or more uses. Example uses of coatings in lithographic apparatus include: position control of the immersion liquid; preventing certain materials from coming into contact with the immersion liquid; absorption, transmission or reflection of the radiation beam. The invention can be applied to any outer layer present on an object.

The object itself may be used as a substrate for the outer layer (i.e., a supporting base substance on which devices are formed or a layer opposite the wafer, which is sometimes referred to as a substrate in different cases), or the object may have one or more underlying layers located below the outer layer. The lower layer is not necessarily a layer directly on the substrate, but rather is lower relative to the outer layer. The lower layer is located between the substrate and the outer layer.

In the present invention, an intermediate layer (sometimes referred to as an interface layer) may be positioned between the outer layer and the substrate or lower layer (if present).

The invention will be described in detail below with reference to a sensor mark comprising a quartz substrate, one or more lower layers for interacting with a radiation beam, and an outer layer (sometimes referred to as a hydrophobic coating or coating) having a limited hydrophilicity, e.g. water, having a receding contact angle with the outer layer of at least 75 °, preferably at least 90 °.

Fig. 3, 4 and 5 illustrate a prior art sensor mark formed on a substrate, such as a quartz (SiO2) plate 200. The sensor's markers are integrated into a stack of thin films 300, which is deposited on top of a quartz plate 200. The quartz plate 200 is integrated into the support table WT. The stack of thin films 300 may include any number of layers. As illustrated in fig. 3, 4 and 5, the stack 300 comprises four layers, layer 310, layer 320 and layer 330 being layers for absorbing DUV radiation projected onto the sensor mark from above (as illustrated) and for absorbing radiation from below the quartz plate 200 (which may be emitted by the material 600 below the quartz plate 200, the material 600 emitting visible light when irradiated by the DUV radiation). Lower layer 350 (lower relative to outer layer 400) is formed on top of layers 310, 320, 330 of stack 300. In an embodiment, the lower layer 350 is reflective to VIS and/or NIR and/or MIR radiation.

To provide some measurement, the sensor passes under the liquid confinement structure 12, so the sensor marks are covered by the immersion liquid. These measurement sensors are removed from the immersion liquid after passing again under the liquid confinement structure 12. In order to avoid that liquid is left on the stack 300 on and/or around the sensor mark, an outer layer 400 having a limited hydrophilicity is applied to and/or around the sensor mark.

Having explained the application of the sensor marks in a lithographic apparatus, the layers and the purpose of their manufacture will now be described in more detail.

The sensor flag functions as:

-spatial transmission type filters for Deep Ultraviolet (DUV) (PARIS, ILIAS, TIS functions); and

spatial reflection filters for VIS, NIR, MIR (SMASH function).

Also, reflections from the top surface of the stack 300 (unmarked areas) may be used by other sensors.

Currently, the sensor marks are generated by the following sequence, with reference to fig. 3:

1) successive layers of blue chromium (CrOx-Cr-CrOx)310, 320, 330 are deposited on the quartz plate 200, with a total thickness of-100 nm (e.g., 50-200 nm). Blue chromium 310, 320, 330 is required to minimize secondary reflection of visible light from the material 600 placed under the quartz plate 200. This material 600 converts the DUV into visible light that is captured by the sensor. The DUV from the projection system PS passes through the vias 100 patterned in the blue chrome 310, 320, 330. The composition of CrOx is Cr₂O₃、CrO_xN_yOr CrO_xN_yC_z. The layers within blue chrome 310, 320, 330 are: the bottom layer 310 is CrO with the thickness of 10-80nm_x(ii) a The middle layer 320 is 5-60nm thick Cr; the top layer 330 is CrO with a thickness of 20-100nm_x。

2) The patterns for the PARIS/ILIAS/TIS/SMASH marks (1D and 2D gratings) and other marks are lithographically deposited and then etched in the blue chrome 310, 320, 330 until the quartz surface (which acts as an etch stop) is exposed. The vias 100 are patterned.

3) A TiN layer 350 is deposited on top of the blue chromium 310, 320, 330 and the quartz plate 200, with a total thickness of up to 300nm or less than 100nm, the layer 350 conforming to the pattern. This layer 350 will provide a marker for measuring reflection via VIS/NIR/MIR without light leaking through the quartz through these markers (VIS/IR/DUV). This layer can be considered as a radiation blocking layer.

4) On top of the layer (lower layer) 350 is applied a coating with limited hydrophilicity (e.g. with e.g. a Si-O-Si-O backbone, preferably with e.g. Si-O-Si-O backbone, etc.)Such as a methyl group, an inorganic polymer). In the following reference is made to Lipocer (but this is not intended to be limiting). For example, the outer layer 400 may include any inorganic and/or silicone polymer. The polymer may have one or more groups selected from methyl, ethyl, propyl, phenyl, vinyl. During the time that the support table WT with the sensor is moved from under the liquid confinement structure 12, Lipocer is deposited on the lower (TiN) layer 350, which minimizes water loss. The outer layer (the Lipocer layer) typically has a thickness of 1-300nm, but may be thicker, for example, up to 500 nm.

5) In some spots on the sensor plate (DUV dose expected to be high at the spot due to the measurement procedure), Lipocer is absent, e.g. removed (typically the spot is-100X 100 μm)²But it may also be larger, e.g., -2X 2cm²)。

Some of the spots will also be stripped of TiN, allowing the DUV to pass to the surface of the quartz plate 200 through the via 100 in the blue chrome 310, 320, 330. Such spots are usually above TIS, ILIAS and pari (see fig. 3).

In fig. 3 and 4:

the grating is not proportional, typical tile size (i.e. the size of the squares of the pattern), the line width of the grating is 1-10 μm.

The DUV (projected through the reticle marks and lens) passes through the through-hole 100 in the blue chrome 310, 320, 330.

IR/VIS (source from SMASH measurement system) reflects mainly from the Lipocer/TiN interface; some reflection may also occur at the TiN/blue chromium interface.

The level sensor is based on reflections from Lipocer and/or TiN.

Figure 3 shows a PARIS stack (and ILIAS). Fig. 4 shows a SMASH stack. Fig. 5 shows PARIS marks and SMASH marks produced in the same manufacturing sequence on a common quartz plate 200.

To prevent galvanic corrosion of Cr (which forms a pair with the stainless steel of liquid confinement structure 12), the entire sensor flag may be biased with respect to grounded liquid confinement structure 12.

The outer layer 400 made of Lipocer suffers from degradation in the lithographic apparatus. The degradation results from direct and scattered illumination due to the DUV. As a result of the illumination due to DUV (directly or indirectly), Lipocer becomes more hydrophilic. It is considered that the decrease in hydrophobicity is caused by CH₃The cleavage of the radicals leads to situations in which the water content can no longer be guaranteed. Water may remain on the sensor flag. Water remaining on the sensor mark may cause a focus error due to a level sensor misreading or leaving a droplet or contaminant. Because of the evaporated liquid, the dried droplets may cause temperature fluctuations of the sensor marks, thereby causing sensor damage. It is believed that high energy photons from the DUV radiation can break down the molecular chain and leave the methyl radical behind in the Lipocer. The reaction replaces the hydrophilic methyl hydroxyl end group.

Additionally or alternatively, exposure to DUV and illumination from the sensor (especially SMASH laser) may cause shrinkage of the Lipocer layer. This shrinkage can cause the opening in the Lipocer layer to tear. Thus, in the event of a tear in layer 350, any TiN may be oxidized. The oxidized TiN absorbs DUV radiation and can thus accelerate the degradation process due to temperature fluctuations. Oxidized TiN may cause unacceptable drift in sensor readings.

The above two mentioned problems are mainly associated with degradation of the Lipocer due to exposure to water and DUV radiation. The deterioration is caused by oxidation or shrinkage. Shrinkage is the result of the removal of relatively large methyl (non-polar) groups, which are substituted with polar, smaller hydroxyl (-OH) groups, which therefore also induce additional stress by interacting with other polar groups in the environment.

In the present invention, the outer layer has a composition including a rare earth element. The inventors have found that this outer layer is hydrophobic due to the elongated bond length formed with the rare earth element (e.g. rare earth element-oxygen bond) and is also more robust in aqueous environments with DUV radiation. Furthermore, such coatings are transparent to DUV radiation.

The large interatomic distance between the rare earth element and oxygen (or other elements, e.g., C, Si, B, N) means that the hydrophobicity has a different source compared to Lipocer. In Lipocer, the presence of methyl, ethyl, propyl, phenyl or vinyl groups results in hydrophobicity. However, when a rare earth element is used in the outer layer 400, hydrophobicity is caused by a large interatomic distance. Unlike Lipocer, where the polarity of the methyl group results in hydrophobicity, the hydrophobicity of rare earth oxides (or from extended carbides, silicides, nitrides, and borides) is a result of the unit cell size and shape within the crystal lattice. Thus, unlike Lipocer, oxidation or substitution of methyl groups with hydroxyl groups does not adversely affect the hydrophilicity of the layer. Such a layer is capable of interacting with water to give a receding contact angle of at least 75 ° or even at least 90 °.

When the outer layer is first prepared, the rare earth element may be bonded to oxygen atoms (at least partially oxidized). Alternatively or additionally, the rare earth element may be bonded to an oxygen atom during use. Alternatively or additionally, the rare earth elements may be partially nitrided, borated, carbonated or siliconized prior to or during use, and such compounds show similar properties to rare earth element oxides.

Fig. 8 shows various rare element oxides and their associated advancing water contact angles. The receding contact angle can be expected to be proportional to the advancing water contact angle. Therefore, the most promising rare earth elements are cerium, dysprosium, erbium, holmium, samarium and thulium in terms of hydrophobicity, and these rare earth elements are preferable. However, any rare earth element is expected to exhibit hydrophobicity. Lanthanum and yttrium may be preferred because they are less expensive.

In the first embodiment, the rare earth element is present in the outer layer 400 along with the inorganic and/or silicone polymer. One such exemplary polymer is Lipocer, and the invention will be described with reference to Lipocer. However, the invention is not limited to Lipocer and other inorganic and/or silicone polymers may be used, in particular inorganic and/or silicone polymers based on a Si-O-Si-O backbone (like Lipocer).

In the examples, the rare earth elements partially replace Si in the Si-O-Si-O backbone. Fig. 6 shows a typical Lipocer structure, and fig. 7 shows how this structure changes when a rare earth element (REM) replaces a Si atom in the main chain. As can be seen, the bond length between the rare earth element and oxygen is longer than the bond length between Si and oxygen. This contributes to hydrophobicity.

Lipocer can be deposited in multiple stages, making its bottom layer the densest. In the presence of large amounts of oxygen in the plasma, more CH is present₃The radicals are removed and it is closer to pure SiO₂(Aquacer), otherwise more CH₃The radical remains attached and it is a true Lipocer.

Initiation of plasma-initiated polymerization as shown above.

Possible plasma-initiated polymerization from Lipocer of HMDSO as shown above.

The chemical reaction (plasma-induced polymerization) above illustrates that deposition in an oxygen-rich plasma results in a composition closer to that of SiO₂(by removal of CH)₃A base).

In an embodiment, the composition of the outer layer includes a rare earth element and an inorganic and/or silicone polymer, such as Lipocer. The resulting structure may be a polymeric and/or mixed rare earth element. The outer layer may have a slightly reduced transparency compared to the pure Lipocer layer. In an embodiment, the concentration of the rare earth element in the outer layer is between 0.1 atomic percent and 50 atomic percent. This ensures that sufficient rare earth elements are present to improve the degradation performance of the outer layer without excessive rare earth elements reducing the transmittance of the outer layer. Preferably, the transmittance (at normal incidence) of the outer layer is at least 50% of the deep ultraviolet radiation, more preferably at least 90% of the deep ultraviolet radiation. In a preferred embodiment, the concentration of the rare earth element in the outer layer is between 2.0 atomic percent and 30 atomic percent. Such a concentration has an optimum balance between improved deterioration performance and high transmittance of deep ultraviolet radiation.

In embodiments, the rare earth element and the Lipocer can be (co) deposited by sputtering a rare earth element target or using a metal vapor arc source (e.g., a rare earth electrode). The target may be co-sputtered by the same or a different plasma source as used in polymer deposition, or a metal vapor arc source may be engaged, which may be performed with or alternating with polymer deposition. In either case (co-deposition or alternating deposition), a structure similar to that in fig. 7 is contemplated. The shallower depth of the rare earth implant in the polymer indicates that the energy of the ions or atoms incident on the polymer is lower.

In an embodiment, instead of sputtering or ion implantation, the rare earth elements may be deposited by Physical Vapor Deposition (PVD) and/or Chemical Vapor Deposition (CVD) and/or Atomic Layer Deposition (ALD) techniques. In PVD, CVD and ALD, at least one of the precursors and/or reactive gases comprises a rare earth element to be deposited in the outer layer.

In an alternative method of deposition, as described above, a rare earth element compound in volatile form is introduced along with the Lipocer polymer precursor during the deposition of the Lipocer present in the oxidizing plasma. An inert gas may also be included. Examples of rare earth element compounds in volatile form include triacetylacetonate, chelates, and other organometallic compounds. Such deposition results in a structure such as that illustrated in fig. 7.

By selecting an appropriate ratio of polymer to rare earth metal, it is possible to reduce the aging effect of the polymer in terms of contact angle. That is, as the methyl groups are removed, the contact angle of the outer layer will be driven more and more by the presence of the rare earth element-oxygen bond rather than by the initial presence of methyl groups on the surface. In addition, the self-healing properties of the polymer may be improved. This is because the presence of rare earth elements in the main chain (see fig. 7) leaves more room for adjacent methyl groups to rotate. Thereby, the degree of freedom of the methyl group rotating to fill the gap of the methyl group which has been removed is improved. Thereby, the self-healing properties of the polymer are improved.

In embodiments, it may be beneficial to increase the amount of rare earth elements, thereby altering the optical or chemical properties of the outer layer. In embodiments, the addition of sufficient rare earth elements can make the polymer more reflective to DUV radiation incident at grazing incidence angles, or less susceptible to oxidation. Then, degradation of the outer layer driven by the scattered DUV together with, for example, UPW outside the transmissive sensor signature can be reduced.

In the examples, Lipocer is made of SiO₂And (4) substitution.

In an embodiment, to carry out the polymerization or SiO in multiple steps₂Or SiO_2-xAnd rare earth elements are deposited. Rare earth elements and/or polymers or SiO₂Or SiO_2-xThe deposition may occur by sputtering, PVD, CVD and/or ALD or combinations thereof. Ideally, multiple deposition steps are performed without exposing the layer to atmosphere, for example by maintaining a vacuum around the layer between deposition movements.

In embodiments, the inorganic or organosilicon polymer is deposited by plasma-initiated polymerization, and/or SiO₂Or SiO_2-xDeposited by sputtering or ALD.

In use (after exposure to air or UPW), deposition of SiO by sputtering or ALD is terminated due to many-OH groups₂/SiO_2-xAnd (3) a layer. This is illustrated in fig. 9. Such layers are hydrophilic (-OH groups are polar and have a good aspect ratio to the host water molecule or host water molecules). However, such a layer is beneficial because it has good chemical properties and is amenable to DUV irradiation in the presence of waterIs robust. By adding rare earth elements, the hydrophilicity will be reduced without compromising mechanical and chemical properties. Such a structure is illustrated in fig. 10. Thus, the outer layer may be considered to comprise rare earth element oxides (and extends to borides, nitrides, carbides, silicides).

In an embodiment, the SiO is deposited by sputtering or preferably ALD₂After the layer, the rare earth element is deposited. Alternatively, the structure may be formed by co-deposition, e.g. co-sputtering, SiO₂And rare earth elements.

A sufficiently thin layer of rare earth oxide (e.g., 1-30nm) is transparent and does not distort DUV or visible radiation transmission.

In an embodiment, a concentration gradient is established across the thickness of the outer layer. For example, the concentration of the rare earth element increases as one moves away from the substrate through the thickness of the outer layer. This can be achieved by: varying the concentration of the rare earth element during co-deposition, or varying the time of each deposition step in those embodiments where the deposition of the rare earth element is interspersed with the deposition of another substance. Preferably, the deposition is such that the concentration of rare earth elements in the outer surface of the outer layer is greater than 10 atomic percent, as this will ensure a sufficiently high level of hydrophobicity.

In a preferred embodiment, SiO is deposited by ALD₂Layer, followed by SiO deposited by sputtering₂Layer, followed by sputtered SiO₂And a transition layer of sputtered rare earth element oxide followed by a final sputtered layer of rare earth element oxide.

In an embodiment, ALD SiO₂The layer is then sputtered SiO₂Layer, followed by SiO deposited by sputtering₂And a mixed layer of ReOX. The concentration gradient in the mixed layer may be changed so that the concentration of the rare earth element oxide on the outer side of the mixed layer is highest.

In an embodiment, no transition layer is required, such that the outer layer may comprise SiO deposited by atomic layer deposition₂SiO deposited by sputtering₂And rare earth element oxides deposited by sputtering.

In an embodiment, the SiO deposited by atomic layer deposition is sputtered directly₂And depositing rare earth element oxide on the layer. In such an embodiment, SiO₂The layer will have a thickness of 50-100nm and the sputtered rare earth element oxide layer has a thickness of less than 30nm, preferably less than 10 nm.

Although the invention is described with respect to an outer layer 400 formed on an underlying layer 350 (e.g., TiN), other nitrides having comparable properties may also be used (such as CrN, AlTiN, and TiAlN and ZrN, etc.). Additionally or alternatively, additional layers (e.g., SiO)₂Layer) may be formed between lower layer 350 and outer layer 400.

The invention has been described above with respect to sensor marks and a hydrophobic layer or coating having limited hydrophilicity. However, the present invention may be applied to other surfaces of the sensor and objects other than the sensor (e.g., lens elements, support stages, etc.).

Although specific reference may be made in this text to the use of lithographic apparatus in the manufacture of ICs, it should be understood that the lithographic apparatus described herein may have other applications, such as the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat-panel displays, liquid-crystal displays (LCDs), thin-film magnetic heads, etc. Those skilled in the art will appreciate that, in the context of such alternative applications, any use of the terms "wafer" or "die" herein may be considered as synonymous with the more general terms "substrate" or "target portion", respectively. The substrate referred to herein may be processed, before or after exposure, in for example a track or coating and developing system (a tool that typically applies a layer of resist to a substrate and develops the exposed resist), a metrology tool and/or an inspection tool. Where applicable, the disclosure herein may be applied to such and other substrate processing tools. In addition, the substrate may be processed more than once, for example in order to create a multi-layer IC, so that the term substrate used herein may also refer to a substrate that already contains multiple processed layers.

The terms "radiation" and "beam" used herein encompass all types of electromagnetic radiation, including Ultraviolet (UV) radiation (e.g. having a wavelength of or about 365nm, 248nm, 193nm, 157nm or 126 nm).

The term "lens", where the context allows, may refer to any one or combination of various types of optical components, including refractive, reflective, magnetic, electromagnetic and electrostatic optical components.

While specific embodiments have been described above, it will be appreciated that embodiments of the invention may be practiced otherwise than as described. The above description is intended to be illustrative and not restrictive. Thus, it will be apparent to those skilled in the art that modifications may be made to the invention without departing from the scope of the aspects set out below. Other aspects of the invention are set forth below, in the following numbered aspects:

1. an immersion lithographic apparatus comprising:

an object, the object comprising:

a substrate and an outer layer, the outer layer being in contact with an immersion liquid in use,

wherein the outer layer has a composition including a rare earth element.

2. The immersion lithographic apparatus of clause 1, wherein the composition further comprises an inorganic and/or silicone polymer.

3. The immersion lithographic apparatus of clause 2, wherein the polymer has a Si-O-Si-O backbone.

4. The immersion lithographic apparatus according to clause 3, wherein a portion of the rare earth element partially replaces Si in the backbone.

5. The immersion lithographic apparatus according to clause 2, 3 or 4, wherein the polymer has one or more groups selected from methyl, ethyl, propyl, phenyl, vinyl.

6. The immersion lithographic apparatus of any one of clauses 1-4, wherein the rare earth element is at least partially oxidized, nitrided, boronated, carbonized, or silicided.

7. The immersion lithographic apparatus of any one of clauses 1-6, further comprising an intermediate layer between the substrate and the outer layer.

8. The immersion lithographic apparatus of clause 7, wherein the intermediate layer comprises one or more of SiO2, SiO 2-x.

9. The immersion lithographic apparatus according to any one of clauses 7 or 8, wherein the intermediate layer has a thickness of between 1nm and 1 μm, preferably between 10nm and 300 nm.

10. The immersion lithographic apparatus according to any one of clauses 1-9, wherein the outer layer has a concentration gradient of the rare earth element over the layer thickness that increases with increasing distance from the substrate.

11. The immersion lithographic apparatus according to any one of clauses 1-10, wherein the rare earth element is present in the outer surface of the outer layer at a concentration (atomic%) of 0.1 to 50 atomic%, preferably 2.0 to 30 atomic%.

12. The immersion lithographic apparatus of any one of clauses 1-11, wherein the rare earth element is present in the outer surface of the outer layer at a concentration greater than 10 atomic%.

13. The immersion lithographic apparatus according to any one of clauses 1-12, wherein the outer layer has a thickness between 1nm and 300nm, preferably between 1nm and 30 nm.

14. The immersion lithographic apparatus according to any one of clauses 1 to 13, comprising at least one patterned layer comprising a pattern of through-holes formed on the substrate and/or a pattern of steps formed in the through-holes, and wherein the outer layer is formed on at least a portion of the patterned layer.

15. The immersion lithographic apparatus of any one of clauses 1 to 14, further comprising a radiation blocking layer formed on the substrate below the outer layer.

16. An immersion lithographic apparatus according to clause 15, wherein the radiation blocking layer comprises TiN.

17. The immersion lithographic apparatus according to any one of clauses 1 to 16, wherein the outer layer is transmissive to deep ultraviolet radiation, wherein the transmittance of the outer layer is at least 50%, preferably at least 90%.

18. The immersion lithographic apparatus of any one of clauses 1 to 17, wherein the receding contact angle of water with the outer layer is at least 75 °, preferably at least 90 °.

19. The immersion lithographic apparatus of any one of clauses 1-18, wherein the object is a sensor.

20. An immersion lithographic apparatus according to clause 19, wherein the sensor comprises a spatially transmissive filter for deep ultraviolet light.

21. An immersion lithographic apparatus according to clause 19 or claim 20, wherein the sensor is a transmission image sensor or an integrated lens interferometer sensor.

22. The immersion lithographic apparatus of any one of clauses 1-19, wherein the object is a sensor mark.

23. An immersion lithographic apparatus according to clause 22, wherein the sensor marks the spatial reflection type filter.

24. An immersion lithographic apparatus according to clause 22 or 23, wherein the sensor mark is a sensor mark of an alignment sensor.

25. The immersion lithographic apparatus of any one of clauses 1-24, wherein the rare earth element is one or more elements selected from the group consisting of cerium (Ce), lanthanum (La), yttrium (Y), dysprosium (Dy), erbium (Er), holmium (Ho), samarium (Sm), thulium (Tm).

26. An immersion lithographic apparatus according to any one of clauses 1-25, wherein the outer layer is exposed, in use, directly or indirectly to deep ultraviolet radiation.

27. An object for a lithographic apparatus, comprising:

a substrate and an outer layer, wherein

A receding contact angle of water with the outer layer of at least 75 °; and is

The outer layer has a composition including a rare earth element.

28. A method of coating a substrate comprising:

providing a substrate;

depositing an outer layer having a composition including a rare earth element on the substrate by at least one of:

(a) sputtering, wherein at least one of the sputtering target materials comprises a rare earth element, and (b) PVD and/or CVD and/or ALD, wherein at least one of the precursors/reactive gases comprises a rare earth element, and (c) plasma-induced (co) polymerization, and (d) ion implantation, wherein the ion source is a metal vapor arc source, and the vapor at least partially comprises a rare earth.

29. The method of clause 28, wherein the deposition of the component comprising a rare earth element is preceded by or alternated with the deposition of (a) an inorganic/silicone polymer or (b) any of SiO2 or SiO2-x, such that the component comprises the polymer or SiO 2.

30. The method of clause 29, wherein the deposition of the composition comprising a rare earth element precedes or alternates with the deposition of the inorganic/silicone polymer by PVD and/or plasma-initiated polymerization such that the composition comprises the polymer.

31. The method of clause 29, wherein the deposition of the component comprising a rare earth element precedes or alternates with the deposition of SiO2 or SiO2-x by sputtering or ALD such that the component comprises SiO 2.

32. The method of clause 28, wherein the deposition of the composition including rare earth elements is a deposition of polymerized and/or copolymerized and/or mixed rare earth elements.

33. The method of clause 28 or 32, wherein the composition further comprises an inorganic and/or silicone polymer deposited by PVD or plasma-initiated polymerization.

34. The method of any one of clauses 28 to 33, wherein the rare earth elements are at least partially oxidized, nitrided, boronated, carbonized, or silicided.

35. A method of coating a substrate comprising:

providing a substrate;

exposing the substrate to an oxidizing atmosphere comprising a compound of a rare earth element in volatile form and an inorganic/organosilicon polymer precursor, thereby depositing an outer layer on the substrate, the outer layer comprising a copolymerized and/or covalently bonded inorganic monomer and rare earth element.