JP2007088061A - Exposure apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exposure apparatus which is not easily influenced by noise from a light source and assures excellent exposure performance. <P>SOLUTION: The exposure apparatus for transferring a pattern on a reticle to a substrate comprises an EUV light source 110 including a plasma generating mechanism, a light collecting mirror 113 for collecting the light radiated from the plasma, a first vessel 10 accommodating the plasma generating mechanism, and the light collecting mirror and having a first aperture 116 which is almost matched with the collecting point of lights collected by the light collecting mirror; a lighting optical system 130 for guiding the light 120 from the EUV light source to a reticle 170; a projection optical system 180 for projecting the light reflected from the reticle to the substrate based on the scale-down system; and second vessels 11, 12 having a second aperture for guiding the light to the lighting optical system from the EUV light source. In this exposure apparatus, the first vessel and the second vessel are spatially coupled via an insulting material 1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to various devices having fine patterns such as semiconductor chips such as IC and LSI, liquid crystal panels, CCDs, thin film magnetic heads, micromachines, and the like and exposure apparatuses used for producing fine patterns used in micromechanics. In particular, the present invention relates to noise countermeasures for an exposure apparatus that uses extreme ultraviolet (EUV) light as a light source.

2. Description of the Related Art A reduction projection exposure apparatus has been conventionally used when a fine semiconductor element such as a semiconductor memory or a logic circuit is manufactured by using a photolithography technique. The reduction projection exposure apparatus projects a circuit pattern drawn on a reticle (or mask) onto a wafer or the like by a projection optical system and transfers the circuit pattern.
The minimum dimension (resolution) that can be transferred by the reduction projection exposure apparatus is proportional to the wavelength of light used for exposure and inversely proportional to the numerical aperture (NA) of the projection optical system. Therefore, the shorter the wavelength, the better the resolution. For this reason, the wavelength of exposure light has been shortened in accordance with the recent demand for miniaturization of semiconductor elements. The wavelength of ultraviolet light used has been shortened to ultra-high pressure mercury lamp (i-line (wavelength: about 365 nm)), KrF excimer laser (wavelength: about 248 nm), and ArF excimer laser (wavelength: about 193 nm).

  However, semiconductor elements are rapidly miniaturized, and there is a limit in lithography using ultraviolet light. Therefore, in order to efficiently transfer a very fine circuit pattern of 0.1 μm or less, there is a reduction projection exposure apparatus using extreme ultraviolet (EUV) light having a wavelength shorter than that of ultraviolet light and having a wavelength of about 10 nm to 15 nm. Has been developed. Hereinafter, this exposure apparatus is referred to as an “EUV exposure apparatus”. An EUV exposure apparatus typically uses a laser plasma (LPP) light source (LPP light source) or a discharge (DPP) light source (DPP light source) as a light source.

  The LLP light source irradiates a target material (metal thin film, inert gas, droplets, etc.) supplied into the vacuum vessel with a gas jet or the like with a high-intensity pulse laser to generate high-temperature plasma. For example, EUV light having a wavelength of about 13 nm, which is emitted from such plasma, is used. On the other hand, the DPP light source applies a high voltage between the electrodes and generates a plasma by flowing a gas such as xenon and discharging it to generate EUV light. These EUV light sources are provided with a condensing mirror that condenses EUV light from plasma in order to efficiently use EUV light.

  EUV light is easily absorbed by air, nitrogen, etc., and the mirror surface is contaminated with a polymer organic gas, or the mirror surface is oxidized and the reflectivity is lowered. Therefore, the EUV exposure apparatus performs exposure in a state where an illumination optical system, a projection optical system, a reticle, and an object to be exposed are housed in a vacuum container and the inside thereof is maintained in a vacuum or a reduced pressure environment.

  Since the LPP light source uses a target supply mechanism that supplies a target at a high frequency using a piezoelectric element or the like as a driving source, vibration noise and high frequency noise are generated. In the DPP light source, high voltage noise is generated by applying a high voltage of several kV between the anode and the cathode electrodes and switching them in order to generate plasma. Due to the high-frequency noise and the plasma itself has a spatial potential, the vacuum vessel of the light source is affected by the influence and the ground potential of the light source fluctuates. Also, the illumination optical system, projection optical system, reticle, and vacuum container of the object to be exposed connected to the metal vacuum container are similarly affected. In other words, this adversely affects circuits and detectors arranged in the vacuum vessel, for example, a light amount monitor for detecting the light amount.

In view of this, a proposal for a method of reducing noise in a vacuum vessel has been made conventionally (see, for example, Patent Document 1). The EUV exposure apparatus disclosed in Patent Document 1 divides a plurality of pressure zones into PO, RS, and WS spaces, forms a plurality of zones with different pressures, and is vibration-insulated from the indication tray of the zoning member and the vacuum container, Vibration noise is reduced by providing a conductance limiting member that isolates vibration and maintains a pressure difference between the pressure zone and the second pressure zone.
US Pat. No. 6,333,775

As described above, in an EUV light source, high-frequency noise is generated from a target supply mechanism that supplies a target at a high speed using a space potential generated by plasma and a piezoelectric element. In the DPP light source, high-frequency noise is generated by switching a high voltage of several kV applied between the electrodes. However, Patent Document 1 is intended to reduce noise related to vibration in the EUV exposure apparatus. The high frequency noise is not removed. For this reason, accurate information cannot be obtained from the detector used by being disposed in the vacuum container of the EUV exposure apparatus. In other words, noise generated from the light source travels through the vacuum container of the light source, and also affects the illumination optical system, the projection optical system, the reticle, and the vacuum container of the object to be exposed. Therefore, an error is included in the detection result of the detector arranged in the exposure apparatus, and thus accurate information of the EUV exposure apparatus cannot be obtained. As a result, the imaging performance, the overlay accuracy, and the exposure performance such as the throughput are deteriorated, so that the exposure with high accuracy cannot be performed. As a result, it also causes an increase in cost.
Therefore, an object of the present invention is to provide an exposure apparatus that can exhibit excellent exposure performance that is not easily affected by noise from a light source.

  An exposure apparatus for solving the above problems includes a light emitting apparatus that emits exposure light using plasma, a first container in which at least a part of the light emitting apparatus is disposed, and exposure from the light emitting apparatus. A second container in which at least a part of an illumination optical system for guiding light to the reticle is disposed, and the space in the first container and the space in the second container are in each container It is connected through the provided opening, and an insulator is arrange | positioned between each container, It is characterized by the above-mentioned.

  ADVANTAGE OF THE INVENTION According to this invention, the exposure apparatus which can exhibit the outstanding exposure performance which is hard to receive to the influence of the noise from a light source can be provided.

In the present embodiment, the EUV light source unit, the illumination optical system unit, and the projection optical system unit are disposed in separate vacuum containers, and the vacuum containers are coupled via an insulator. You may connect between vacuum vessels with a cylindrical metal housing. In that case, an insulator may be disposed between the vacuum vessel and the metal housing, and the vacuum vessel and the metal housing may be fastened with the insulator.
Further objects and other features of the present invention will become apparent from the preferred embodiments described below with reference to the accompanying drawings.

  An exposure apparatus according to an embodiment of the present invention will be described below with reference to the accompanying drawings. In addition, in each figure, the same reference number is attached | subjected about the same member and the overlapping description is abbreviate | omitted. Here, FIG. 1 is a schematic sectional view showing the arrangement of the exposure apparatus according to the present embodiment. The exposure apparatus of FIG. 1 has an EUV light source vacuum container 10, illumination optical system vacuum containers 11, 12, and a projection optical system vacuum container 13, and has a connecting portion 1 that connects them. Details of the connecting portion 1 are shown in FIG. The connection portion 1 sandwiches the insulator 2 therebetween, and the vacuum vessels are insulated so that the vacuum vessels are not electrically connected. Although not shown here, a turbo pump and a dry pump are connected to each vacuum vessel so that evacuation can be performed.

  The exposure apparatus of FIG. 1 uses EUV light (for example, wavelength 13.5 nm) as illumination light for exposure. Then, for example, the circuit pattern formed on the reticle 170 is projected and exposed to the object 190 such as a semiconductor wafer by the step-and-repeat method or the step-and-scan method. Such an exposure apparatus is suitable for a lithography process of submicron or quarter micron or less. Hereinafter, in this embodiment, a step-and-scan exposure apparatus (also referred to as a “scanner”) will be described as an example. In the “step and scan method”, the wafer is continuously scanned (scanned) with respect to the reticle to expose the reticle pattern onto the wafer. After one shot of exposure is completed, the wafer is stepped to the next exposure. This is an exposure method for moving to an area. The “step-and-repeat method” is an exposure method in which the wafer is stepped and moved to the exposure area of the next shot for every batch exposure of the wafer.

The exposure apparatus in FIG. 1 includes an EUV light source (light emitting device) 110, an illumination optical system 130, a reticle stage 174 on which a reticle 170 is placed, a projection optical system 180, and a wafer stage on which an object 190 is placed. Have
Further, EUV light has a low transmittance with respect to the atmosphere and generates contamination due to a reaction with a residual gas (polymer organic gas) component. Therefore, as shown in FIG. 1, at least in the optical path through which EUV light passes (that is, the entire optical system) is a vacuum environment (VC).

  The EUV light source unit 110 uses a laser plasma light source, and has an excitation laser unit (not shown) including an excitation laser light source and a condensing optical system. Further, the nozzle 111, the collection unit 112, the condensing mirror 113, the debris removal member 114, the wavelength filter 115, and the aperture 116 are included. Note that the EUV light source 110 shown in FIG. 1 can be replaced with a DPP light source. The target material supplied from the target supply mechanism is irradiated with laser light LB to generate plasma EP. EUV light 120 is emitted from the plasma EP. This target supply mechanism uses, for example, a piezoelectric element, etc. Since the frequency synchronized with a light emission pulse of about several kHz or a multiplied frequency thereof is used for driving, noise is generated, which affects the light source vacuum vessel. Effect. In addition, since the conventional vacuum vessels were connected to each other, the effect on the illumination optical system vacuum vessel and the projection optical system vacuum vessel affected the circuit installed inside the vacuum vessel. Was giving.

  In the present embodiment, in order to reduce the influence of these noises on detectors and the like in other vacuum vessels, the following configuration is adopted. That is, as shown in FIG. 1, the EUV light source vacuum container 10, the illumination optical system vacuum containers 11 and 12, and the projection optical system vacuum container 13 are arranged as independent vacuum containers. Each of the vacuum vessel 10 and the vacuum vessel 11 has an opening, and the spaces in each vessel are coupled through the opening. Each of the vacuum container 12 and the vacuum container 13 has an opening, and the spaces in each container are coupled through the opening. Further, the connection part 1 between the vacuum vessels 10 and 11 and between the vacuum vessels 12 and 13 is arranged such that the insulators 2 and 3 are arranged as shown in FIG. Arranged. Here, the vacuum vessel 11 and the vacuum vessel 12 may be the same vessel, but are individually configured to reduce the influence of contamination. The mirror 155 of the illumination optical system 130 is disposed in the projection optical system vacuum container 13, and it is not always necessary that all the components of the illumination optical system are disposed in the illumination optical system vacuum containers 11 and 12. The same applies to the light source vacuum container and the projection optical system vacuum container, and some of the components may be arranged in another container. The EUV light source vacuum vessel 10 and the illumination optical system vacuum vessel 11 were coupled via a metal housing 104. At that time, the insulating portion 1 was disposed between the illumination optical system vacuum vessel 11 and the metal housing 104.

  FIG. 2 is a view showing the details of the connecting portion 1 of the vacuum vessel of FIG. Two metal flanges 4 are sandwiched between insulators 2 (for example, ceramic plates) and tightened with bolts 5 via the insulators 3. By doing so, there is no electrical connection. The insulator may be a material that is not electrically conductive, does not affect the vacuum, and is less degassed.

  FIG. 3 shows an electrical connection diagram of the vacuum vessels that are electrically independent of each other as shown in FIGS. Here, an example of noise countermeasures in the circuit is given. A drive circuit 6 and detection circuits 7 and 8 are arranged in each of the EUV light source vacuum container 10, the illumination optical system vacuum containers 11 and 12, and the projection optical system vacuum container 13. The EUV light source vacuum container 10, the illumination optical system vacuum containers 11 and 12, and the projection optical system vacuum container 13 are not shown, but are each connected to an electric wire and connected to a ground (earth) 27. The EUV light source vacuum container 10 is connected to the light source circuit BOX 17, and the GND part (G) of the internal power supply circuit 18 is connected from the frame 24 (frame ground) to the ground 27 (earth). The other power source V is connected to the frame ground 24 via the ferrite bead 25 and the ceramic capacitor 26. The illumination optical system vacuum containers 11 and 12 and the projection optical system vacuum container 13 are connected to a detector circuit BOX 16. The inside of the detector circuit BOX 16 is divided into a power supply circuit 19, an analog circuit 20, and a digital circuit 21, which are connected from a frame ground 23 to a ground 27 (earth) through different paths. In this embodiment, in order to make the potential of the GND point of each circuit constant, the GND points of each circuit are collected and connected to one point.

In this way, the electrical connection between the vacuum containers is cut, and grounding (earth) connection is made with independent wirings, and circuits arranged in the vacuum containers are also connected with independent paths. Accordingly, it is possible to provide an exposure apparatus that can exhibit excellent exposure performance that is not easily affected by noise from the light source.
The preferred embodiments of the present invention have been described above, but the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the gist.

[Example of device manufacturing]
Next, a manufacturing process of a micro device (a semiconductor chip such as an IC or LSI, a liquid crystal panel, a CCD, a thin film magnetic head, a micromachine, etc.) using this exposure apparatus will be described.
FIG. 4 shows a flow of manufacturing a semiconductor device.
In step 1 (circuit design), a semiconductor device circuit is designed. In step 2 (mask production), a mask on which the designed pattern is formed is produced.
On the other hand, in step 3 (wafer manufacture), a wafer is manufactured using a material such as silicon. Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by lithography using the wafer and the exposure apparatus provided with the prepared mask.
The next step 5 (assembly) is called a post-process, and is a process for forming a semiconductor chip using the wafer manufactured in step 4. The post-process includes assembly processes such as an assembly process (dicing and bonding) and a packaging process (chip encapsulation). In step 6 (inspection), the semiconductor device manufactured in step 5 undergoes inspections such as an operation confirmation test and a durability test. A semiconductor device is completed through these processes, and is shipped in Step 7.

  The wafer process in step 4 includes an oxidation step for oxidizing the surface of the wafer, a CVD step for forming an insulating film on the wafer surface, and an electrode formation step for forming electrodes on the wafer by vapor deposition. Also, an ion implantation step for implanting ions into the wafer, a resist processing step for applying a photosensitive agent to the wafer, and an exposure step for printing and exposing the circuit pattern on the wafer after the resist processing step by the exposure apparatus described above. Further, there are a development step for developing the wafer exposed in the exposure step, an etching step for removing portions other than the resist image developed in the development step, and a resist stripping step for removing the resist that has become unnecessary after the etching. By repeating these steps, multiple circuit patterns are formed on the wafer.

It is a schematic sectional drawing which shows the structure of the exposure apparatus which concerns on one Example of this invention. It is a schematic sectional drawing of the connection part of the exposure apparatus shown in FIG. It is a figure which shows an example of the electrical connection of the exposure apparatus shown in FIG. It is a figure explaining the flow of the manufacturing process of a device.

Explanation of symbols

1: Connection part 2, 3: Insulator 4: Metal flange 5: Bolt 6: Drive circuit 7, 8: Detection circuit 10: EUV light source vacuum container 11, 12: Illumination optical system vacuum container 13: Projection optical system vacuum container 16 : Detector circuit BOX
17: Light source circuit BOX
18, 19: Power supply circuit 20: Analog circuit 21: Digital circuit 23, 24: Frame (frame ground)
25: Ferrite beads 26: Capacitor (capacitance)
27: Grounding
104: Metal housing 110: EUV light source 120: EUV light flux 130: Illumination optical system 170: Reticle 190: Object to be processed (wafer)

Claims (8)

A light emitting device that emits exposure light using plasma;
A first container in which at least a part of the light emitting device is disposed;
A second container in which at least a part of an illumination optical system for guiding exposure light from the light emitting device to a reticle is disposed,
The exposure in which the space in the first container and the space in the second container are coupled through an opening provided in each container, and an insulator is disposed between the containers. apparatus.   The exposure apparatus according to claim 1, further comprising an exhaust device for evacuating the inside of the first and second containers. A third container in which at least a part of a projection optical system for projecting exposure light reflected by the reticle onto a wafer is disposed;
The space in the second container and the space in the third container are coupled through an opening provided in each container, and an insulator is disposed between the containers. Item 3. The exposure apparatus according to Item 1 or 2.   The exposure apparatus according to claim 3, further comprising an exhaust device for evacuating the inside of the third container.   The light emitting device includes at least one of a plasma generating device for generating plasma and a condensing mirror for condensing light emitted from the generated plasma. The exposure apparatus described in 1.   The first power supply means for supplying power to the first electric circuit disposed in the first container and the first power supply means are independent of each other and are disposed in the second container. Second power supply means for supplying power to the second electric circuit, the first container to the frame ground of the first power supply, and the second container to the frame ground of the second power supply. The exposure apparatus according to claim 1, wherein the exposure apparatus is connected.   The exposure apparatus according to claim 1, wherein each container is grounded through an independent wiring path. A device manufacturing method comprising: exposing a substrate using the exposure apparatus according to claim 1; and developing the exposed substrate.

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