radiation sensor

Abstract

As a radiation sensor for detecting EUV radiation, the radiation sensor comprises: a radiation receiving side for receiving radiation to be detected; a substrate layer including a photodiode on the radiation receiving side; a cathode configured to collect charge from the photodiode; and a side shielding part configured to shield the photodiode from radiation incident into the substrate layer from the opposite side of the side shielding part, wherein the side shielding part extends from the radiation receiving side into the substrate layer.

Description

Technology Field

[0001] This application claims priority to EP application 23214138.2 filed on December 5, 2023, the full text of which is incorporated herein by reference.

[0002] The present invention relates to a radiation sensor for detecting EUV radiation, a stage, an EUV lithography apparatus, and a method for manufacturing the radiation sensor. Background Technology

[0003] A lithography device is a machine designed to apply a desired pattern to a substrate. Lithography devices can be used, for example, in the manufacture of integrated circuits (ICs). For example, a lithography device can project a pattern onto a layer of radiation-sensitive material (resist) provided on a substrate from a patterning device (e.g., a mask).

[0004] To project a pattern onto a substrate, a lithography device may use electromagnetic radiation. The wavelength of this radiation determines the minimum size of the features that can be formed on the substrate. For example, a lithography device using extreme ultraviolet (EUV) radiation with a wavelength within the 4 to 20 nm range, such as 6.7 nm or 13.5 nm, can be used to form smaller features on a substrate than a lithography device using radiation with a wavelength of, for example, 193 nm.

[0005] It is desirable to know the dose of the EUV radiation being used. Radiation sensors can be used to detect radiation from the radiation beam. However, radiation other than the beam can also contribute to the measurement of the radiation sensor. This can undesirably reduce detection accuracy. The problem to be solved

[0006] The objective of the present invention is to improve the accuracy of radiation detection by a radiation sensor. means of solving the problem

[0007] According to one embodiment, a radiation sensor for detecting EUV radiation is provided, the radiation sensor comprises: a radiation receiving side for receiving radiation to be detected; a substrate layer including a photodiode on the radiation receiving side; a cathode configured to collect charge from the photodiode; and a side shielding part configured to shield the photodiode from radiation incident on the substrate layer from the opposite side of the photodiode with respect to the side shielding part and / or shield the cathode from charge moving from the opposite side of the cathode with respect to the side shielding part, wherein the side shielding part extends into the substrate layer from the radiation receiving side.

[0008] According to another embodiment, a method for manufacturing a radiation sensor for detecting EUV radiation is provided, the method comprising: providing a substrate layer; forming a photodiode within the substrate layer on the radiation receiving side of the radiation sensor; electrically connecting the cathode to the photodiode so as to be configured to collect charge from the photodiode; and forming a side shield extending into the substrate layer from the radiation receiving side, wherein the side shield is configured to shield the photodiode from radiation incident on the substrate layer from the opposite side of the photodiode with respect to the side shield and / or shield the cathode from charge moving from the opposite side of the cathode with respect to the side shield. Brief explanation of the drawing

[0009] Now, embodiments of the present invention will be described merely as examples with reference to the attached schematic drawings. FIG. 1 illustrates a lithography system including a lithography device and a radiation source. Figure 2 schematically illustrates a radiation sensor. Figure 3 schematically illustrates a plan view of the radiation sensor of Figure 2. Figure 4 schematically illustrates the radiation sensor of Figure 2 with the photodiode exposed. Figure 5 schematically illustrates an alternative radiation sensor. Figure 6 schematically illustrates an alternative radiation sensor. FIGS. 7 to 11 schematically illustrate the steps of a method for manufacturing the radiation sensor of FIG. 2. Specific details for implementing the invention

[0010] FIG. 1 illustrates a lithography system composed of a radiation source (SO) and a lithography device (LA). The radiation source (SO) is configured to generate an EUV radiation beam (B) and supply the EUV radiation beam (B) to the lithography device (LA). The lithography device (LA) includes an illumination system (IL), a support structure (MT) configured to support a patterning device (e.g., a mask), a projection system (PS), and a substrate table (WT) configured to support a substrate (W).

[0011] The illumination system (IL) is configured to condition the EUV radiation beam (B) before the EUV radiation beam (B) is incident on the patterning device (MA). Accordingly, the illumination system (IL) may include a faceted field mirror device (10) and a faceted pupil mirror device (11). The faceted field mirror device (10) and the faceted pupil mirror device (11) together provide an EUV radiation beam (B) having a desired cross-sectional shape and a desired intensity distribution. The illumination system (IL) may include other mirrors or devices in addition to or instead of the faceted field mirror device (10) and the faceted pupil mirror device (11).

[0012] After being conditioned in this way, the EUV radiation beam (B) interacts with the patterning device (MA). As a result of this interaction, a patterned EUV radiation beam (B') is generated. A projection system (PS) is configured to project the patterned EUV radiation beam (B') onto a substrate (W). To this end, the projection system (PS) may include a plurality of mirrors (13, 14) configured to project the patterned EUV radiation beam (B') onto a substrate (W) accommodated in a substrate table (WT). The projection system (PS) may apply a reduction factor to the patterned EUV radiation beam (B') to form an image having features smaller than the corresponding features on the patterning device (MA). For example, a reduction factor of 4 or 8 may be applied. Although the projection system (PS) is shown in FIG. 1 as having only two mirrors (13, 14), the projection system (PS) may include a different number of mirrors (e.g., six or eight mirrors).

[0013] The substrate (W) may include a pre-formed pattern. In this case, the lithography device (LA) aligns an image formed by a patterned EUV radiation beam (B') with the pre-formed pattern on the substrate (W).

[0014] A small amount of gas (e.g., hydrogen) at a relative vacuum, that is, a pressure much lower than atmospheric pressure, can be supplied to a radiation source (SO), an illumination system (IL), and / or a projection system (PS).

[0015] The radiation source (SO) may be a laser-generated plasma (LPP) source, a discharge-generated plasma (DPP) source, a free electron laser (FEL), or any other radiation source capable of generating EUV radiation.

[0016] In one embodiment, the lithography device (LA) includes at least one radiation sensor (20). The radiation sensor (20) is intended to measure the energy of EUV radiation. The radiation sensor (20) is intended to measure the energy of patterned EUV radiation (B') associated with the radiation of an EUV radiation beam (B) or EUV radiation (e.g., radiation having a wavelength within the range of 4 to 20 nm). The radiation beam (B) and the patterned EUV radiation beam (B') may include combined radiation (15) comprising both EUV radiation and non-EUV radiation. The radiation sensor (20) is intended to measure the energy associated with the EUV radiation component of the combined radiation.

[0017] FIG. 2 schematically illustrates one embodiment of a radiation sensor (20). The radiation sensor (20) is intended to detect EUV radiation. In one embodiment, the radiation sensor (20) may be used to detect other types of radiation, namely non-EUV radiation. The radiation sensor (20) is described below primarily in the context of detecting EUV radiation.

[0018] As illustrated in FIG. 2, the radiation sensor (20) includes a radiation receiving side (33). The radiation receiving side (33) is for receiving radiation to be detected. FIG. 2 schematically illustrates the radiation (30) to be detected. The radiation (30) is incident on the radiation sensor (20) at the radiation receiving side (33) of the radiation sensor (20). In one embodiment, the radiation (30) includes a radiation beam (B) or patterned EUV radiation (B').

[0019] As illustrated in FIG. 2, in one embodiment, the radiation sensor (20) comprises a substrate layer (21). The substrate layer (21) may be substantially flat. One of the main surfaces of the substrate layer (21) may be oriented toward the radiation receiving side (33) of the radiation sensor (20). In one embodiment, the substrate layer (21) comprises a semiconductor. For example, in one embodiment, the substrate layer (21) comprises silicon. Alternatively, the substrate layer (21) may comprise germanium.

[0020] As illustrated in FIG. 2, in one embodiment, the substrate layer (21) includes a photodiode (26). The photodiode (26) is configured to receive radiation (30). The photodiode (26) is configured to convert the received radiation (30) into an electric charge. The photodiode (26) can generate an electric current when it absorbs photons of radiation (30). The photodiode (26) may be referred to as a photodetector or a transducer.

[0021] As illustrated in FIG. 2, the photodiode (26) is located on the radiation receiving side (33) of the radiation sensor (20). As illustrated in FIG. 2, in one embodiment, the photodiode (26) is located on the radiation receiving side (33) of the substrate layer (21). The photodiode (26) may be formed on or near the upper surface of the substrate layer (21). The term 'upper' is used to refer to the direction as illustrated in FIG. 2. The upper surface may correspond to the surface where the radiation (30) to be detected is incident on the radiation sensor (20).

[0022] By positioning a photodiode (26) on the radiation receiving side (33), the possibility of the radiation (30) to be detected being absorbed before reaching the photodiode (26) can be reduced. If the photodiode (26) is spaced apart from the radiation receiving side (33), the radiation (30) will be absorbed more by the material of the substrate layer (21) before reaching the photodiode (26). This is particularly important in the case of radiation that is generally easily absorbed, such as EUV radiation. One embodiment of the present invention is expected to improve the measurement accuracy of the radiation (30).

[0023] As illustrated in FIG. 2, in one embodiment, the radiation sensor (20) includes a cathode (27). The cathode (27) is configured to collect charge from a photodiode (26). The charge output by the photodiode (26) can be collected at the cathode (27). The charge collected at the cathode (27) may be a measure of the radiation (30) to be detected. Electrons may move from the photodiode (26) toward the cathode (27) and thereby generate a photocurrent.

[0024] As illustrated in FIG. 2, in one embodiment, the radiation sensor (20) includes an electrical connection (28). The electrical connection (28) is configured to electrically connect the cathode (27) to the photodiode (26). In one embodiment, the electrical connection (28) includes one or more vias. In one embodiment, the electrical connection (28) includes electrical wiring, for example, one or more electrical wires and / or traces.

[0025] As illustrated in FIG. 2, in one embodiment, the radiation sensor (20) includes a side shield (29). The side shield (29) may be located on one side of the photodiode (26). In one embodiment, the side shield (29) is configured to shield the photodiode (26) from radiation incident on the substrate layer (21) from the opposite side of the side shield (29). For example, in the diagram illustrated in FIG. 2, some radiation may enter the radiation sensor (20) undesirably from the left side of the side shield (29). This radiation may be detected by the photodiode (26). This radiation may be separate from the radiation (30) to be detected. For example, this radiation may be separate from the radiation beam (B) or patterned EUV radiation (B').

[0026] As illustrated in FIG. 2, in one embodiment, the side shield (29) extends from the radiation receiving side (33) into the substrate layer (21). A portion of the substrate layer (21) remains on the opposite side of the photodiode (26) relative to the side shield (29). The side shield (29) may be spaced apart from the radially outer perimeter of the radiation sensor (20). The side shield (29) may help reduce the amount of radiation that undesirably contributes to the detection of the photodiode (26). One embodiment of the present invention is expected to improve the accuracy of radiation detection by the radiation sensor (20).

[0027] For comparison, an alternative method attempting to shield the photodiode from light incident from the side is to coat the sensor's sidewalls, for example, with aluminum. When the sensor sidewalls are coated, the coating is typically non-uniform and may contain pinholes—points where the sidewall is exposed without coating. This is because the sensor's sidewalls may be rough, at least partially. For example, the sidewalls can become rough due to the dicing process. As a result, light still partially passes through the sidewalls, thereby degrading the accuracy of radiation detection.

[0028] As illustrated in FIG. 2, the side shield (29) may be located near the side wall of the radiation sensor (20). However, the side shield (29) is spaced apart from the side wall. The side shield (29) can more effectively prevent radiation from undesirably penetrating through the side wall and reaching the photodiode (26).

[0029] In one embodiment, the side shield (29) is configured to shield the cathode (27) from charges moving from the opposite side of the side shield (29). As shown in FIG. 2, a portion of the substrate layer (21) remains on the opposite side of the side shield (29) from the photodiode (26) and the cathode (27). Due to radiation incident on this portion, pairs of electrons and holes may be generated. These electrons may be referred to as photoelectrons. In one embodiment, the side shield (29) is configured to reduce or prevent the diffusion of photoelectrons from the sidewall to the cathode (27). An embodiment of the present invention is expected to improve the measurement accuracy by the radiation sensor (20).

[0030] As illustrated in FIG. 2, in one embodiment, the side shield (29) extends beyond the photodiode (26) in a direction away from the radiation receiving side (33). In the orientation illustrated in FIG. 2, the radiation receiving side (33) is the upper side. The side shield (29) extends into the substrate layer (21) in a direction away from the radiation receiving side (33). In the orientation illustrated in FIG. 2, the direction away from the radiation receiving side (33) is the downward direction. The side shield (29) extends downward to one side of the photodiode (26). The side shield (29) extends beyond the photodiode (26). The bottom of the side shield (29) is below the bottom of the photodiode (26). The side shield (29) extends further into the depth of the substrate layer (21) and the photodiode (26).

[0031] In one embodiment, the side shield (29) extends from the receiving side (33) into the substrate layer (21) by at least 5 μm, optionally at least 10 μm, optionally at least 20 μm, and optionally at least 50 μm. As the side shield (29) extends deeper into the substrate layer (21), the measurement contribution due to radiation incident on the radiation sensor (20) from the opposite side of the side shield (29) generally decreases. For every 10 μm increase in the depth of the side shield (29), the contribution can be expected to decrease by a factor of two.

[0032] In one embodiment, the side shield (29) extends into the substrate layer (21) by a distance of up to 100 μm, optionally up to 50 μm, optionally up to 20 μm, and optionally up to 10 μm. By reducing the depth of the side shield (29), the manufacturing cost of the radiation sensor (20) can be reduced. Additionally, the structural integrity of the radiation sensor (20) can be increased.

[0033] As illustrated in FIG. 2, in one embodiment, the side shield (29) comprises a material (31). In one embodiment, the material (31) is configured to absorb radiation. In one embodiment, the material (31) is opaque to incoming radiation. The material (31) is configured to absorb rays of radiation incident on the side shield (29). In one embodiment, the material (31) is configured to absorb substantially all types of radiation that may be incident on the radiation sensor (20). Any type of radiation may potentially contribute to the measurements performed by the radiation sensor (20). Thus, it is desirable to reduce the possibility that any type of radiation incident on the radiation sensor (20) from the opposite side of the side shield (29) may contribute to the measurements.

[0034] In one embodiment, the side shield (29) comprises a material configured to reflect radiation. For example, the material (31) of the side shield (29) may be reflective for at least some types of radiation. The side shield (29) may be configured to reflect radiation rays incident on the side shield (29).

[0035] In one embodiment, the side shield (29) comprises a metal. For example, the material (31) of the side shield (29) may be a metal. Such a metal may preferably absorb radiation. For example, in one embodiment, the metal is tungsten. However, other types of metal may be used for the side shield (29). For example, molybdenum or chromium may be used.

[0036] As described above, in one embodiment, the side shield (29) comprises metal. In an alternative embodiment, the side shield (29) comprises an electrical insulator. The electrical insulator can shield the cathode (27) from charges moving from the opposite side of the side shield (29).

[0037] As illustrated in FIG. 2, in one embodiment, the side shield (29) is positioned within a groove formed in the substrate layer (21). A material (31) is positioned within the groove to form the side shield (29). As illustrated in FIG. 2, in one embodiment, the side shield (29) substantially fills the groove. That is, the material (31) forming the side shield (29) substantially fills the groove to form the side shield (29). The side shield (29) may have a thickness substantially equal to the width of the groove in the substrate layer (21). The groove may be referred to as a trench. The side shield (29) may be a trench filled with tungsten.

[0038] FIG. 3 schematically illustrates a plan view of a radiation sensor (20). The drawing in FIG. 3 is a top view of the radiation sensor (20) shown in FIG. 2. The drawing in FIG. 3 is a view from the radiation receiving side (33) of the radiation sensor (20).

[0039] As illustrated in FIG. 3, in one embodiment, the side shield (29) substantially surrounds the photodiode (26) when viewed from the radiation receiving side (33). In FIG. 3, the side shield (29) is shown as a dashed line because it may not be exposed due to the presence of the top shield (32) as illustrated in FIG. 2. By substantially surrounding the photodiode (26), the side shield (29) can shield the photodiode (26) and / or cathode (27) from radiation and / or photoelectrons incident from all directions of the radiation sensor (21). However, in an alternative embodiment, the side shield (29) is located on only one side, only two sides, or only three sides of the photodiode (26). Depending on the location of the radiation sensor (20), it may not be necessary to provide side shields (29) on one or more sides of the photodiode (26).

[0040] As illustrated in FIG. 3, in one embodiment, the side shield (29) forms a rectangle in the plan view. However, in an alternative embodiment, the side shield (29) may form a polygonal shape such as a pentagon, a hexagon, etc., or may be an ellipse such as a circle.

[0041] FIG. 4 schematically illustrates the radiation sensor (20) of FIG. 2 in use. As illustrated in FIG. 4, in one embodiment, a photodiode (26) is exposed on the radiation receiving side (33) of the radiation sensor (20). The photodiode (26) may include an exposed surface (34) upon which radiation (30) is incident. In one embodiment, a dielectric layer (25) is provided on the substrate layer (21). A portion of the dielectric layer (25) may be removed to expose the photodiode (26) for use with the radiation sensor (20). By removing the dielectric layer (25), the absorption of radiation (30) by the dielectric layer (25) may be reduced or eliminated.

[0042] As illustrated in FIG. 2, in one embodiment, the radiation sensor (20) includes a lower shield (22). The lower shield (22) is located on the side opposite to the photodiode (26) facing the radiation receiving side (33). The photodiode (26) is located between the lower shield (22) and the incident radiation (30). The lower shield (22) is configured to shield the photodiode (26).

[0043] In one embodiment, the lower shield (22) is configured to shield the photodiode (26) from radiation from the opposite side of the lower shield (22). In the arrangement shown in FIG. 2, the opposite side of the lower shield (22) is shown below the lower shield (22). The lower shield (22) can prevent radiation from below the lower shield (22) from reaching the photodiode (26). For example, the lower shield (22) may be configured to absorb radiation. In one embodiment, the lower shield (22) is configured to reflect radiation. In one embodiment, radiation in the upward direction in the orientation shown in FIG. 2 can be substantially completely reflected by the lower shield (22).

[0044] In one embodiment, the lower shield (22) is configured to shield the cathode (27) from charges moving from the opposite side of the lower shield (22). For example, when radiation is incident on the radiation sensor (20) without passing through the radiation receiving side (33), the radiation reaching the opposite side of the lower shield (22) [i.e., below the lower shield (22) shown in FIG. 2] can cause photoelectrons to be generated. In one embodiment, the lower shield (22) is configured to block photoelectrons from reaching the cathode (27). The lower shield (22) may be configured to function as a barrier to prevent electron diffusion from below the lower shield (22) to the cathode (27).

[0045] As illustrated in FIG. 2, in one embodiment, the radiation sensor (20) includes an additional substrate layer (23). The additional substrate layer (23) exists in addition to the substrate layer (21) which includes a photodiode (26). In one embodiment, the base material for the additional substrate layer (23) is substantially the same as the base material of the substrate layer (21). For example, in one embodiment, the additional substrate layer (23) is a semiconductor, e.g., silicon or germanium.

[0046] As illustrated in FIG. 2, in one embodiment, the lower shielding portion (22) is located between the substrate layer (21) and the additional substrate layer (23). In one embodiment, the substrate (24) comprises the substrate layer (21), the lower shielding portion (22), and the additional substrate layer (23). In one embodiment, the substrate (24) is a layered silicon-insulator-silicon substrate.

[0047] In one embodiment, the lower shield (22) includes an electrical insulator. For example, in one embodiment, the electrical insulator is an oxide such as silicon dioxide. In one embodiment, the substrate (24) is formed by silicon-on-insulator (SOI) technology. The lower shield (22) can be formed easily and inexpensively during the manufacture of the radiation sensor (20).

[0048] In an alternative embodiment, the lower shielding portion (22) includes an electrical conductor. The electrical conductor may be configured to discharge charges within the substrate. The electrical conductor may reduce the likelihood of charges undesirably reaching the cathode (27).

[0049] By providing a lower shielding portion (22), the possibility that unwanted radiation will have an undesirable effect on the measurement by the photodiode (26) is reduced. One embodiment of the present invention is expected to improve the accuracy of the radiation sensor.

[0050] As illustrated in FIG. 2, in one embodiment, the lower shield (22) extends beyond the photodiode (26) when viewed from the radiation receiving side (33). In a top view of the radiation sensor (20), the photodiode (26) may be seated within the lower shield (22). For example, as illustrated in FIG. 2, in one embodiment, the lower shield (22) extends substantially over the entire substrate layer (21). The lower shield (22) provides an effective barrier against photoelectrons traveling to the cathode (27).

[0051] As illustrated in FIG. 2, in one embodiment, the side shield (29) extends beyond the lower shield (22) in a direction away from the radiation receiving side (33). In the drawing illustrated in FIG. 2, the side shield (29) extends below the lower shield (22). A portion of the side shield (29) is located on the opposite side of the lower shield (22) from the photodiode (26). The side shield (29) can penetrate the lower shield (22). This helps to prevent radiation from undesirably entering the lower shield (22).

[0052] By extending the side shielding portion (29) beyond the lower shielding portion (22), the photocurrent contribution from stray radiation can be reduced by about three orders of magnitude compared to the case where the side shielding portion (29) stops at the lower shielding portion (22). One embodiment of the present invention is expected to improve the accuracy of radiation measurement.

[0053] As illustrated in FIG. 2, in one embodiment, the radiation sensor (20) includes an upper shield (32). The upper shield (32) may also be referred to as an upper shield. The upper shield (32) is configured to shield the photodiode (26) from radiation incident on the radiation sensor (20) from outside the radiation receiving area on the radiation receiving side (33) of the radiation sensor (20). The radiation receiving area may correspond to a target area on the radiation receiving side (33) of the radiation sensor (20). For example, in the arrangement illustrated in FIG. 3, the radiation receiving area may be defined by the radially inner edge of the upper shield (32).

[0054] As illustrated in FIG. 2, the upper shield is positioned on the radiation receiving side (33) of the radiation sensor (20). For example, as illustrated in FIG. 2, in one embodiment, the upper shield (32) is provided over the side shield (29). In one embodiment, the side shield (29) and the upper shield (32) are adjacent to each other. For example, the material (31) of the side shield (29) may come into contact with the upper shield (32). By placing the side shield (29) adjacent to the upper shield (32), the possibility of radiation or photoelectrons undesirably passing between the upper shield (32) and the side shield (29) can be reduced or eliminated.

[0055] As illustrated in FIG. 3, in one embodiment, the upper shield (32) substantially surrounds the radiation receiving area when viewed from the radiation receiving side (33). In one embodiment, the upper shield (32) defines the radiation receiving area. The radiation receiving area is the area through which radiation (30) passes to be incident on the photodiode (26). However, in an alternative embodiment, the upper shield (32) may extend around only one, two, or three of the four sides of the radiation receiving area of ​​the photodiode (26).

[0056] In one embodiment, the upper shield not only surrounds a significant area of ​​the radiation receiving side of the radiation sensor (20) but also covers / overlays it. In one embodiment, the upper shield (32) comprises a material configured to absorb radiation. For example, in one embodiment, the upper shield (32) comprises metal. The upper shield (32) may be formed as a metal coating on the upper surface of the radiation sensor (20).

[0057] In one embodiment, the side shield (29) and / or the top shield (32) overlay the entire area excluding the target area on the radiation receiving side (33). The target area may be a place intended to capture EUV radiation.

[0058] FIG. 5 schematically illustrates an alternative radiation sensor (20). Among the features of the radiation sensor (20) illustrated in FIG. 5, those identical to the features of the radiation sensor (20) illustrated in FIG. 2 are not described below. The features of the radiation sensor (20) illustrated in FIG. 5 are identical to those illustrated in FIG. 2, but have the following differences.

[0059] In the arrangement shown in FIG. 2, the side shield (29) substantially fills the groove to form the side shield (29). However, as shown in FIG. 5, in an alternative embodiment, the side shield (29) is located on the inner surface of the groove formed in the substrate layer (21). The material (31) forming the side shield (29) may be located on the inner surface of the groove. For example, as shown in FIG. 5, in one embodiment, the material (31) substantially lines the groove to form the side shield (29). One embodiment of the present invention is expected to reduce the material cost for manufacturing the radiation sensor (20).

[0060] In one embodiment, the side shield (29) comprises a plurality of layers. The layers may be metal layers. In an alternative embodiment, the layers may be a combination of dielectric layers and metal layers. The layers may be arranged as a stack of layers. In one embodiment, the side shield (29) comprises an adhesive layer configured to adhere to an inner surface. In one embodiment, the side shield (29) comprises one or more layers adjacent to the adhesive layer. The adhesive layer may be positioned between the inner surface and one or more other layers. In one embodiment, the adhesive layer comprises TiN. TiN is a material with higher adhesion.

[0061] In the arrangement shown in FIG. 2, the side shield (29) extends below the lower shield (22). However, in an alternative embodiment as shown in FIG. 5, the side shield (29) may not extend beyond the lower shield (22) in a direction away from the radiation receiving side (33). As shown in FIG. 5, in one embodiment, the side shield (29) and the lower shield (22) are adjacent to each other. By bringing the side shield (29) into contact with the lower shield (22), the possibility of radiation or photoelectrons passing between the side shield (29) and the lower shield (22) may be reduced.

[0062] As illustrated in FIG. 5, the upper shielding portion (32) may be omitted. In one embodiment, the side shielding portion (29) is exposed on the radiation receiving side (33) of the radiation sensor (20).

[0063] FIG. 6 schematically illustrates an alternative radiation sensor (20). The features of the radiation sensor (20) illustrated in FIG. 6 are the same as those described above with reference to FIG. 2, except as otherwise described below.

[0064] As shown in FIG. 6, in one embodiment, the substrate (24) is composed of a substrate layer (21). An additional substrate layer (23) may be omitted. As shown in FIG. 6, the lower shielding portion (22) may be omitted. An embodiment of the present invention is expected to simplify the manufacture of the radiation sensor (20).

[0065] As illustrated in FIGS. 2 and 4, in one embodiment, the substrate (24) comprises a first substrate layer (21) and an additional substrate layer (23). In one embodiment, the additional substrate layer (23) is doped. For example, the additional substrate layer (23) may be N-doped. By doping the additional substrate layer (23), pairs of photoelectrons and holes within the additional substrate layer (23) may be neutralized so that the likelihood of the photoelectron reaching the cathode (27) associated with the photodiode (26) is reduced. An embodiment of the present invention is expected to improve the measurement accuracy of the radiation sensor (20).

[0066] In one embodiment, the radiation sensor (20) is intended to detect EUV radiation. In one embodiment, the radiation sensor (20) includes a filter configured to filter non-EUV radiation received at the radiation receiving side (33). In one embodiment, the filter is configured to prevent non-EUV radiation from reaching the photodiode (26). For example, in one embodiment, the exposed surface (34) of the photodiode (26) includes a filter. In one embodiment, the filter is a bandpass filter. In one embodiment, the filter comprises a material selected from the group consisting of Zr, poly-Si, Al, Ti, TiN, W, and a multilayer comprising one or more of Zr, poly-Si, Al, Ti, TiN, and W.

[0067] In one embodiment, the substrate table (WT) is provided with at least one radiation sensor (20). In one embodiment, the radiation sensor (20) is located radially outward of the substrate (W). In one embodiment, a plurality of radiation sensors (20) are provided on the substrate table (WT). By providing the radiation sensor (20) on the substrate table (WT), the radiation sensor (20) can determine the energy of the EUV radiation reaching the level of the substrate (W). This can help improve the accuracy of measuring the energy of the EUV radiation reaching the substrate (W). Additionally or alternatively, the radiation sensor (20) may be located at other locations along the optical path between the radiation source (SO) and the substrate table (WT). For example, in one embodiment, the lithography device (LA) includes at least one sensor (20) at or near an intermediate focal point [i.e., where the radiation beam (B) is incident on the illumination system (IL) shown in FIG. 1]. In one embodiment, the radiation sensor (20) is provided on or near the faceted field mirror device (10). In one embodiment, at least one radiation sensor (20) is provided on or near the faceted pupil mirror device (11). In one embodiment, at least one radiation sensor (20) is provided on or near the support structure (MT). In one embodiment, at least one radiation sensor (20) is provided on or near at least one of the plurality of mirrors (13, 14) of the projection system (PS). One embodiment of the present invention is expected to improve monitoring of system power in one or more modules of a lithography device (LA).

[0068] In one embodiment, the radiation sensor (20) is provided substantially in the same plane as the substrate (W).

[0069] FIGS. 7 through 11, FIGS. 2, and FIGS. 4 schematically illustrate steps of a method for manufacturing a radiation sensor (20). In one embodiment, the method includes the step of providing a substrate layer (21). For example, as shown in FIG. 7, in one embodiment, a substrate (24) is provided. The substrate (24) may be a layered silicon-insulator-silicon substrate.

[0070] In one embodiment, the method includes the step of oxidizing the surface of a first substrate (21) to form a lower shield (22). The oxidized first substrate layer (21) is then bonded to an additional substrate layer (23), for example, by wafer bonding. Alternatively, the method may include the step of oxidizing an additional substrate layer (23) and then bonding the oxidized additional substrate layer (23) to the substrate layer (21). Alternatively, the lower shield (22) may be formed by ion beam implantation.

[0071] As illustrated in FIG. 8, in one embodiment, the method comprises forming a photodiode (26) on a substrate layer (21). The photodiode (26) is formed on the radiation receiving side (33) of the radiation sensor (20), for example, on the radiation receiving side (33) of the substrate layer (21). In one embodiment, the step of forming the photodiode (26) includes an ion implantation process for forming the photodiode (26).

[0072] As illustrated in FIG. 9, in one embodiment, the method includes the step of electrically connecting the cathode (27) to the photodiode (26) so that the cathode (27) is configured to collect charge from the photodiode (26). In one embodiment, a dielectric layer (25) (e.g., oxide) may be provided on the radiation receiving side (33) of the substrate layer (21). The cathode (27) may be located within the dielectric layer (25). In one embodiment, an electrical connection (28) is formed between the cathode (27) and the photodiode (26).

[0073] As illustrated in FIG. 10, in one embodiment, the method comprises forming a groove (35) in a substrate layer (21). As illustrated in FIG. 10, in one embodiment, the groove (35) penetrates the dielectric layer (25) and extends partially through the substrate (24). In one embodiment, the step of forming the groove (35) includes an etching process such as a reactive ion etching process.

[0074] As illustrated in FIG. 11, in one embodiment, the method comprises the step of forming a side shield (29) extending into the substrate layer (21) from the radiation receiving side (33). The side shield (29) is configured to shield a photodiode (26) from radiation incident on the substrate layer (21) from the opposite side of the side shield (29). In one embodiment, a material (31) is deposited into a groove (35) to form the side shield (29). In one embodiment, the material (31) is deposited conformally. Any material remaining on the upper surface of the device may be removed, for example, by etching and / or chemical mechanical polishing.

[0075] As illustrated in FIG. 2, in one embodiment, the method includes the step of providing an upper shielding portion (32). The upper shielding portion (32) may be positioned above the top of the side shielding portion (29). In one embodiment, the upper shielding portion (32) is formed by a coating method.

[0076] As illustrated in FIG. 4, in one embodiment, the method includes etching a portion of the dielectric layer (25) to expose the exposed surface (34) of the photodiode (26) in the radiation receiving region.

[0077] In one embodiment, the additional substrate (23) is at least 2x10 18 cm -3 , optionally at least 5x10 18 cm -3 , optionally at least 1x10 19 cm -3 , optionally at least 2x1019 cm -3 , and optionally at least 5x10 19 cm -3 It is doped to have a doping concentration of

[0078] As illustrated in FIG. 3, in one embodiment, the radiation sensor (20) includes a single photodiode (26). The side shield (29) surrounds only the single photodiode (26). In an alternative embodiment, the radiation sensor (20) may include a plurality of photodiodes (26). The photodiodes (26) may be provided to be protected by the same side shield (29). The side shield (29) may be formed to surround a plurality of photodiodes (26).

[0079] While this specification may specifically mention the use of lithography devices for the manufacture of ICs, it should be understood that the lithography devices described herein may be used in other applications. Possible other applications include the manufacture of integrated optical systems, guide and detection patterns for magnetic domain memory, flat panel displays, liquid crystal displays (LCDs), and thin-film magnetic heads.

[0080] Although embodiments of the present invention may be specifically referred to in the context of a lithography device in this specification, embodiments of the present invention may be used in other devices. Embodiments of the present invention may constitute part of a mask inspection device, a metrology device, or any device that measures or processes an object such as a wafer (or other substrate) or a mask (or other patterning device). Such devices may generally be referred to as lithography tools. Such lithography tools may utilize vacuum conditions or ambient (non-vacuum) conditions.

[0081] Where the context permits, embodiments of the present invention may be implemented in hardware, firmware, software, or any combination thereof. Embodiments of the present invention may be implemented as instructions stored on a machine-readable medium and may be read and executed by one or more processors. A machine-readable medium may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing device). For example, a machine-readable medium may include read-only memory (ROM), random access memory (RAM), magnetic storage media, optical storage media, flash memory devices, electrical, optical, acoustic, or other forms of radio signals (e.g., carrier waves, infrared signals, digital signals, etc.), and others. Additionally, firmware, software, routines, and instructions may be described herein as performing specific operations. However, it should be understood that such descriptions are merely for convenience, and in reality, such operations occur in a computing device, processor, controller, or other device executing the firmware, software, routines, instructions, etc., and in this process, actuators or other devices may interact with the physical world.

[0082] Although specific embodiments of the present invention have been described above, it will be understood that the invention may be practiced differently from as described. The above description is for illustrative purposes only and is not intended to be limiting. Accordingly, it will be apparent to those skilled in the art that modifications to the present invention as described may be made without departing from the claims set forth below.

Claims

Claim 1 A radiation sensor for detecting EUV radiation, wherein the radiation sensor comprises: a radiation receiving side for receiving radiation to be detected; a substrate layer including a photodiode on the radiation receiving side; a cathode configured to collect charge from the photodiode; and a side shielding portion configured to shield the photodiode from radiation incident on the substrate layer from the opposite side of the photodiode with respect to the side shielding portion, and / or shield the cathode from charge moving from the opposite side of the cathode with respect to the side shielding portion, wherein the side shielding portion extends from the radiation receiving side into the substrate layer. Claim 2 A radiation sensor according to claim 1, wherein the side shielding portion extends beyond the photodiode in a direction away from the radiation receiving side. Claim 3 A radiation sensor according to claim 1 or 2, wherein the side shield comprises a material configured to absorb radiation. Claim 4 A radiation sensor according to any one of claims 1 to 3, wherein the side shielding portion comprises a material configured to reflect radiation. Claim 5 A radiation sensor according to any one of claims 1 to 4, wherein the side shielding part comprises metal. Claim 6 A radiation sensor according to claim 5, wherein the metal is tungsten. Claim 7 A radiation sensor according to any one of claims 1 to 6, wherein the side shielding part comprises an electrical insulator. Claim 8 A radiation sensor according to any one of claims 1 to 7, wherein the side shielding portion is located on the inner surface of a groove formed in the substrate layer. Claim 9 In claim 8, the radiation sensor, wherein the side shielding substantially fills the groove. Claim 10 A radiation sensor according to any one of claims 1 to 9, wherein the side shielding substantially surrounds the photodiode when viewed from the radiation receiving side. Claim 11 A radiation sensor according to any one of claims 1 to 10, comprising a lower shielding portion located opposite the photodiode from the radiation receiving side of the radiation sensor. Claim 12 A radiation sensor according to claim 11, wherein the lower shielding portion is configured to shield the photodiode from radiation incident from the opposite side of the lower shielding portion. Claim 13 A radiation sensor according to claim 11 or 12, wherein the lower shielding portion is configured to shield the cathode from charges moving from the opposite side of the lower shielding portion. Claim 14 A radiation sensor according to any one of claims 11 to 13, wherein the lower shielding portion extends beyond the photodiode when viewed from the radiation receiving side. Claim 15 A radiation sensor according to any one of claims 11 to 14, wherein the side shielding portion and the lower shielding portion are adjacent to each other. Claim 16 A radiation sensor according to any one of claims 11 to 15, wherein the side shielding portion extends beyond the lower shielding portion in a direction away from the radiation receiving side. Claim 17 A radiation sensor according to any one of claims 11 to 16, wherein the lower shielding part comprises an electrical insulator. Claim 18 A radiation sensor according to claim 17, wherein the electrical insulator is silicon dioxide. Claim 19 A radiation sensor according to any one of claims 11 to 16, wherein the lower shielding part comprises an electrical conductor. Claim 20 A radiation sensor according to any one of claims 11 to 19, comprising an additional substrate layer, wherein the lower shielding portion is located between the substrate layers. Claim 21 In claim 20, the radiation sensor, wherein the additional substrate layer is doped. Claim 22 A radiation sensor according to any one of claims 1 to 21, comprising an upper shielding member configured to shield the photodiode from radiation incident on the radiation sensor from outside the radiation receiving area on the radiation receiving side of the radiation sensor, wherein the upper shielding member is located on the radiation receiving side of the radiation sensor. Claim 23 A radiation sensor according to claim 22, wherein the side shielding portion and the upper shielding portion are adjacent to each other. Claim 24 A radiation sensor according to claim 22 or 23, wherein the upper shielding portion substantially surrounds the radiation receiving area when viewed from the radiation receiving side. Claim 25 A radiation sensor according to any one of claims 1 to 24, comprising a filter configured to filter non-EUV radiation received from the radiation receiving side so as not to reach the photodiode. Claim 26 A stage for an EUV lithography apparatus configured to support a reticle or substrate and comprising a radiation sensor according to any one of claims 1 to 24. Claim 27 An EUV lithography apparatus comprising a radiation sensor according to any one of claims 1 to 25 or a stage according to claim 26. Claim 28 A method for manufacturing a radiation sensor for detecting EUV radiation, the method comprising: providing a substrate layer; forming a photodiode within the substrate layer on a radiation receiving side of the radiation sensor; electrically connecting the cathode to the photodiode so as to be configured to collect a charge from the photodiode; and forming a side shielding portion extending from the radiation receiving side into the substrate layer, wherein the side shielding portion is configured to shield the photodiode from radiation incident on the substrate layer from the opposite side of the photodiode with respect to the side shielding portion and / or shield the cathode from a charge moving from the opposite side of the cathode with respect to the side shielding portion. Claim 29 A method according to claim 28, wherein the photodiode is formed to extend less far than the side shielding portion in a direction away from the radiation receiving side. Claim 30 A method according to claim 28 or 29, wherein the step of forming the side shielding portion comprises forming a groove in the substrate layer. Claim 31 In claim 30, the step of forming the side shielding portion comprises applying a material to the inner surface of the groove. Claim 32 A method according to claim 30 or 31, wherein the step of forming the side shield comprises substantially filling the groove with a material. Claim 33 A method according to claim 31 or 32, wherein the material comprises a metal. Claim 34 A method according to any one of claims 30 to 33, wherein the groove is formed to substantially surround the area where the photodiode is formed when viewed from the side of the radiation receiving. Claim 35 A method according to any one of claims 28 to 34, wherein the step of providing the substrate layer comprises providing a substrate including the substrate layer, a lower shielding portion, and an additional substrate layer, wherein the lower shielding portion is located between the substrate layers. Claim 36 In claim 35, the lower shielding portion extends substantially over the entire substrate. Claim 37 A method according to claim 35 or 36, wherein the side shield is formed adjacent to the lower shield. Claim 38 A method according to claim 37, wherein the side shielding portion is formed to extend beyond the lower shielding portion in a direction away from the radiation receiving side. Claim 39 A method comprising the step of doping the additional substrate layer in any one of claims 35 to 38. Claim 40 A method according to any one of claims 28 to 39, comprising the step of forming an upper shielding portion on the radiation receiving side of the radiation sensor, wherein the upper shielding portion is configured to shield the photodiode from radiation incident on the radiation sensor from outside the radiation receiving area on the radiation receiving side of the radiation sensor. Claim 41 In claim 40, the step of forming the upper shielding portion comprises applying a metal layer on the side shielding portion on the radiation receiving side. Claim 42 A method according to any one of claims 28 to 41, comprising the step of applying a dielectric layer to the substrate layer on the radiation receiving side. Claim 43 In claim 42, the method wherein the side shielding portion is formed to extend through the dielectric layer. Claim 44 A method according to claim 42 or 43, comprising the step of removing a region of the dielectric layer so that the photodiode is exposed on the radiation receiving side of the radiation sensor.

Images