JP4724537B2 - Exposure equipment - Google Patents

Description

  The present invention includes an optical element in an apparatus, in which a circuit pattern on an original plate such as a mask is reduced and projected onto a substrate in a manufacturing process of a semiconductor chip such as an IC or LSI, an LCD, or a CCD. The present invention relates to an exposure apparatus and method. The present invention also relates to a device manufacturing method using such an exposure apparatus or exposure method.

In recent years, light sources of exposure apparatuses are increasingly required to have shorter wavelengths, and light in the normal ultraviolet to vacuum ultraviolet region is also used. As the light source becomes a short wavelength such as i-line, KrF excimer laser, ArF excimer laser, F ₂ excimer laser, and EUV light or X-ray, the energy of light gradually increases. The wavelength of i-line is about 365 nm, the wavelength of KrF excimer laser is about 248 nm, the wavelength of ArF excimer laser is about 193 nm, the wavelength of F ₂ excimer laser is about 157 nm, and the wavelength of EUV light is about 15 nm.
Irradiation with short-wave exposure light causes a decomposition reaction, a generation reaction, or an activation reaction of various substances by a photochemical reaction. It is a big problem that such a reaction is involved, a substance is formed on the surface of the optical element, and the optical characteristics of the exposure apparatus deteriorate.

  Thus, such a problem has been addressed by circulating a space containing the optical element with a clean inert gas (see, for example, Patent Document 1). Furthermore, measures have been taken to increase the purity of the introduced gas. For example, in Patent Document 2, by attaching a filter to a gas inlet to the apparatus, impurities contained in the gas of the supply source and impurities generated from the member desorbed gas component when passing through the air supply unit are removed. . In addition to this, as a countermeasure to impurities due to desorbed gas from components in the optical device, a member with less desorbed gas or a component with less influence on the optical performance of the optical element is selected. ing.

Further, a part of oxygen present in the exposure area is changed to ozone by the exposure light. Generally, a part of the air-conditioning gas is circulated for temperature control. Ozone generated there may cause component deterioration, generate desorption gas from the component, or increase the amount of desorption gas. In order to prevent these, an ozone converter for converting ozone into oxygen is sometimes arranged (see Patent Document 3).
Japanese Patent Laid-Open No. 2-210813 JP-A-6-77114 JP 11-274050 A

However, in the case of exposure with a light source having a shorter wavelength than that of the prior art or with high illuminance, the amount of ozone generated by the exposure increases compared to the prior art. For this reason, while moving from the exposure space to the ozone converter, the components existing in the meantime are deteriorated. Also, by generating desorbed gas from the components or increasing the desorbed gas from the member, the amount of impurities in the optical path may be increased and the optical performance of the apparatus may be degraded.
In addition, ozone generated by exposure may promote a reaction for forming a substance on the surface of the optical element in the vicinity. For example, it reacts with an organic silicon compound to form silicon oxide on the surface of the optical element, or reacts with a sulfur-containing compound to form sulfate ions to form sulfate on the surface of the optical element.

The action described above is also present in active oxygen generated from oxygen, ozone, nitrogen oxides, or the like by exposure, or OH radicals generated from water or the like by exposure, and requires countermeasures.
Therefore, an object of the present invention is to suppress / prevent deterioration of parts due to a substance activated by exposure light. Another object is to suppress or prevent the generation of desorbed gas from a part due to a substance activated by exposure light. Alternatively, it is an object to suppress / prevent performance degradation by suppressing / preventing a substance formation reaction on the surface of the optical element.

  In order to solve the above problems, the present invention is characterized in that a substance having an effect of returning these substances to an inactivated state is added to the substance activated by exposure light.

According to the present invention, since the substance activated by exposure is inactivated, it is possible to suppress / prevent the activated substance from deteriorating the parts existing around and downstream of the gas flow path. In addition, it is possible to suppress or prevent the activated substance from generating or increasing desorbed gas from the parts present in the vicinity or downstream of the gas flow path. Furthermore, it can be suppressed / prevented that the activating substance promotes a substance forming reaction on the surface of the optical element.
Therefore, according to the present invention, it is possible to provide an exposure apparatus and method that can reduce deterioration of optical characteristics due to substance formation on the surface of the optical element and also reduce component deterioration.

In a preferred embodiment of the present invention, the additive substance is a hydrocarbon such as carbon monoxide or methane. The additive material is added in the vicinity of the optical path. According to this addition method, a substance activated by exposure light can be immediately inactivated, and deterioration of a member or formation of a substance on an optical element can be suppressed / prevented.
In addition, when the active substance suppresses / prevents generation or increase of desorbed gas from a part existing in the surroundings or downstream of the gas flow path, the above-mentioned additive substance other than in the vicinity of the optical path, such as in the vicinity of the part May be added.

The method of adding the additive substance is characterized in that at least one of the predetermined additive substance amount or gas flow rate is controlled by setting the illumination mode / illuminance of the exposure apparatus. Alternatively, at least one of the additive substance amount and the gas flow rate is controlled by the measured concentration value of the activated substance. Alternatively, at least one of the additive substance amount and the gas flow rate is controlled by the measured value of the exposure illuminance.
According to these addition methods, by adding an appropriate amount of substance, the substance activated by exposure light can be immediately deactivated, suppressing the deterioration of the member or the formation of the substance on the optical element. -It can be prevented.

The additive substance is added so that the concentration in the exposure atmosphere is 1 ppm or less. With such an amount of substance, deterioration of exposure performance due to light absorption of the additive substance itself is not a big problem. Here, the exposure atmosphere indicates at least a portion including an optical path of exposure light and a mask and a wafer.
A device manufacturing method according to another aspect of the present invention includes a step of preparing any one of the exposure apparatuses described above, and a step of performing exposure using the exposure apparatus.

Further problems or other features of the present invention will become apparent from the preferred embodiments described with reference to the accompanying drawings.
Hereinafter, an exposure apparatus and a method for adding a substance to the atmosphere in the apparatus, which are an exemplary embodiment of the present invention, will be described with reference to the drawings. In addition, in each figure, about the same member, the same reference number is attached | subjected and the overlapping description is abbreviate | omitted.

  An embodiment in which the present invention is embodied in an exposure apparatus will be described. FIG. 1 shows a schematic configuration of an entire step-and-scan type ArF exposure apparatus. In the figure, reference numeral 1 denotes an ArF excimer laser light source, which has an oscillation wavelength near 193 nm and emits pulses. In the illumination optical system of this exposure apparatus, the light emitted from the excimer laser light source 1 is bent by the mirror 2, shaped into a predetermined shape via the beam shaping optical system 3, and then optical integrator via the mirror 4. 5 is incident. The optical integrator 5 forms a secondary light source in the vicinity of its emission surface 6. The light beam from the secondary light source is condensed by the first condenser lens 7. In the vicinity of a plane perpendicular to the optical axis including the condensing point 8, a blind 9 for restricting the illumination range is arranged. The light beam from the first condenser lens 7 uniformly illuminates the pattern surface of the mask 13 by the second condenser lens 10, the mirror 11 and the third condenser lens 12. In addition, the optical path including each optical element from the exit of the excimer laser light source 1 to the third condenser lens 12 is housed in the illumination system container 101 and is blocked from the atmosphere outside the apparatus.

  As shown in FIG. 2, this illumination optical system performs slit illumination on a part of a pattern 17 such as a mask 13 with a slit light beam 18. A part of the illuminated pattern 17 is reduced and projected onto the wafer 16 by the projection optical system 14. At this time, the mask 13 and the wafer 16 are scanned in opposite directions as indicated by arrows 111 and 112 at the same speed ratio as the reduction ratio of the projection optical system 14. At the same time, the pattern 17 on the entire surface of the mask 13 is transferred to one chip area or a plurality of chip areas on the wafer 16 by repeating multipulse exposure using pulsed light from the excimer laser light source 1.

  In FIG. 1, reference numeral 21 denotes a mask stage that holds the mask 13, and scan-drives in the direction of the arrow 111 shown in the figure. A bar mirror 22 is fixed to the mask stage 21, a laser interferometer 23 detects the speed of the mask stage 21 using the bar mirror 22, and a wafer chuck 24 holding the wafer 16. Reference numeral 25 denotes a wafer stage holding the wafer chuck 24, which is scan-driven in the direction of the arrow 112 in the figure by a drive system (not shown). A bar mirror 26 is fixed to the wafer stage 25, and a laser interferometer 27 detects the speed of the wafer stage 25 using the bar mirror 26. Reference numeral 102 denotes a mask chamber, and an opening / closing means 28 that can be opened and closed is attached to an exchange port of the mask 13 to switch between an open state and a sealed state.

  Next, FIG. 3 shows a schematic diagram when the present invention is implemented in the vicinity of the projection lens 15 near the wafer 16 in the projection optical system 14. A gas outlet 33 and a gas suction port 36 are provided in the vicinity of the projection lens 15. A gas containing carbon monoxide is ejected from the gas supply unit 31 through the gas supply pipe 32 as shown by an arrow 51 in the drawing. Active substances such as ozone, active oxygen, and OH radicals react with carbon monoxide to be converted into inactive substances. The amount and direction of the gas to be supplied and the timing of supply are controlled by the control system 121 under predetermined conditions in relation to the setting of the illumination mode / illuminance of the exposure apparatus. As shown by the arrow 52 in the figure, the gas is sucked from the gas suction port 36 and is recovered by the gas recovery unit 34 through the gas recovery pipe 35. The suction force and direction in the gas recovery and the recovery timing are also controlled by the control system 121 under predetermined conditions in relation to the setting of the illumination mode and illuminance of the exposure apparatus.

  In this embodiment, carbon monoxide has been described as the substance contained in the gas. However, other substances may be used as long as they can inactivate activated substances such as ozone, activated oxygen, and OH radicals. . For example, a gas to which a hydrocarbon such as methane is added is used. Further, if necessary, a gas added with a plurality of substances may be supplied. In FIG. 3, there are two gas outlets 33 and two gas suction ports 36 on the opposite side, but the number and arrangement thereof are not limited as long as the purpose of inactivating the active substance is achieved. Absent. Further, the gas recovery mechanism including the gas recovery unit 34, the gas recovery pipe 35, and the gas suction port 36 may be omitted if unnecessary.

FIG. 4 shows another example of a method for controlling the amount and direction of gas supplied from the gas outlet 33, the timing of supply, or the amount and direction of gas sucked by the gas suction port 36, and the timing of suction. As shown in FIG. 4, an activation substance concentration measurement mechanism 37 may be provided in the vicinity of the optical path, and control may be performed by the control unit 121 based on the measurement result. As the concentration measuring mechanism of the activated substance, specifically, an ultraviolet absorption method for detecting the absorption using ultraviolet light, a constant potential electrolysis method for detecting a current due to the reaction of the adsorbed substance using an electrode, or the like is used.
The amount and direction of gas supplied from the gas outlet 33, the timing of supply, or the amount and direction of gas sucked at the gas suction port 36, and the timing of suction are determined by measuring the measured value of the exposure illuminance. You may control based on.

In the above embodiment, the structure in which the substance is added to the space between the projection optical system 14 and the wafer 16 is described. However, the present invention is not limited to this, and the present invention may be applied to the space around the mask 13. Good.
In the above embodiment, the step-and-scan type ArF exposure apparatus has been described. However, the same effect can be obtained even if the present invention is applied to a step-and-repeat type exposure apparatus, or an exposure apparatus using KrF laser light, F ₂ laser light, an ultraviolet lamp or EUV light as a light source. In addition, it has been described that the projection lens in the vicinity thereof is contaminated due to the desorption gas from the resist as a cause of contamination, but the same effect can be obtained even if the present invention is applied to other causes of adhesion contamination and optical elements. Can do.

[Example of device manufacturing method]
Next, an example of a device manufacturing method using the above-described exposure apparatus will be described with reference to FIGS. FIG. 5 is a flowchart for explaining how to fabricate devices (ie, semiconductor chips such as IC and LSI, LCDs, CCDs, etc.). Here, the manufacture of a semiconductor chip will be described as an example. In step 1 (circuit design), a device circuit is designed. In step 2 (mask production), a mask on which the designed circuit pattern is formed is produced. 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 mask and wafer. Step 5 (assembly) is called a post-process, and is a process for forming a semiconductor chip using the wafer created in step 4, and includes processes such as an assembly process (dicing and bonding) and a packaging process (chip encapsulation). . In step 6 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device created in step 5 are performed. Through these steps, the semiconductor device is completed and shipped (step 7).

  FIG. 6 is a detailed flowchart of the wafer process in Step 4. In step 11 (oxidation), the surface of the wafer is oxidized. In step 12 (CVD), an insulating film is formed on the surface of the wafer. In step 13 (electrode formation), an electrode is formed on the wafer by vapor deposition or the like. In step 14 (ion implantation), ions are implanted into the wafer. In step 15 (resist process), a photosensitive agent is applied to the wafer. Step 16 (exposure) uses the exposure apparatus to expose a circuit pattern on the mask onto the wafer. In step 17 (development), the exposed wafer is developed. In step 18 (etching), portions other than the developed resist image are removed. In step 19 (resist stripping), the resist that has become unnecessary after the etching is removed. By repeatedly performing these steps, multiple circuit patterns are formed on the wafer. According to the device manufacturing method of this embodiment, it is possible to manufacture a higher quality device than before. Thus, the device manufacturing method using the exposure apparatus and the resulting device also constitute one aspect of the present invention.

1 is an overall schematic view of an exposure apparatus according to an embodiment of the present invention. It is explanatory drawing of the mask in the apparatus of FIG. It is the schematic of the principal part to which this invention was applied in the apparatus of FIG. It is a figure which shows the modification of FIG. It is a flowchart for demonstrating manufacture of devices (semiconductor chips, such as IC and LSI, LCD, CCD, etc.). 6 is a detailed flowchart of the wafer process in Step 4 shown in FIG. 5.

Explanation of symbols

  1: ArF excimer laser, 13: mask, 14: projection optical system, 15: projection lens, 16: wafer, 21: mask stage, 25: wafer stage, 31: gas supply unit, 33: gas ejection port, 34: gas Collection part, 36: gas suction port, 37: activated substance concentration measurement mechanism.

Claims (9)

  An exposure apparatus comprising means for adding a substance effective to return these substances to an inactivated state with respect to a substance activated by exposure light.   2. The exposure apparatus according to claim 1, wherein the additive substance is carbon monoxide or hydrocarbon.   The exposure apparatus according to claim 1, wherein the adding unit adds the additive substance in the vicinity of an optical path.   The apparatus has means for supplying a gas to the exposure atmosphere, and the adding means controls at least one of the amount of the additive substance and the flow rate of the gas in accordance with the illumination mode or illuminance setting state of the exposure apparatus. The exposure apparatus according to any one of claims 1 to 3.   A means for supplying a gas to the exposure atmosphere; and a means for measuring the concentration of the activated substance in the exposure atmosphere, wherein the adding means is responsive to a concentration measurement value of the activated substance. The exposure apparatus according to claim 1, wherein at least one of the amount of the gas and the flow rate of the gas is controlled.   Means for supplying a gas to the exposure atmosphere; and means for measuring exposure illuminance, wherein the adding means is configured to change at least one of the amount of the additive substance and the flow rate of the gas in accordance with the measured value of the exposure illuminance. The exposure apparatus according to claim 1, wherein the exposure apparatus is controlled.     The exposure apparatus according to claim 4, wherein the adding unit adds the additive substance in an amount of 1 ppm or less to the gas in the exposure atmosphere.   An exposure method comprising adding a substance having an effect of returning the substance to an inactivated state to a substance activated by exposure light.   It has the process of exposing a board | substrate using the exposure apparatus of any one of Claims 1-7, or the exposure method of Claim 8, and the process of developing the said exposed board | substrate. Device manufacturing method.

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