JP2004047518A - X-ray exposure device and method for manufacturing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain highly accurate exposure by altering a part of an exposure atmosphere locally thereby controlling the quantity of irradiating pulse light. <P>SOLUTION: The X-ray exposure device for transferring the pattern of an original plate to a substrate in a chamber where the exposure atmosphere is controlled comprises an emission control section (14) for controlling a light source irradiating pulse light, an intensity monitoring section (11) for detecting the quantity of pulse light falling on a substrate, and sections (12, 13) for controlling the quantity of irradiation pulse light by varying the exposure atmosphere of a local region in the chamber based on the detected quantity of the irradiated pulse light. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an X-ray exposure apparatus using a pulse light source used in a semiconductor manufacturing apparatus, and a device manufacturing method using the X-ray exposure apparatus.
[0002]
[Prior art]
In recent years, as the density and speed of semiconductor integrated circuits have been increased, the pattern line width of the integrated circuits has been reduced, and there has been a demand for higher performance semiconductor manufacturing methods. Therefore, even an exposure apparatus used for forming a resist pattern of the lithography process in the semiconductor manufacturing process, KrF laser (wavelength 248 nm), ArF laser (wavelength 193 nm), extreme ultraviolet rays and X-rays such as _{F 2} laser (wavelength 157 nm) Steppers / scanners using progressively shorter exposure wavelengths (wavelength 0.2 to 1.5 nm) have been developed.
[0003]
Of these, the exposure method using X-rays is such that the X-rays are exposed to the X-ray mask while the X-ray mask on which the desired pattern is formed and the resist-coated wafer are brought close to several tens μm to several μm. Irradiation is performed from above (in a direction opposite to the facing wafer), and a close-magnification exposure method is used in which a mask pattern (original pattern) is transferred onto the wafer.
[0004]
In order to obtain high-intensity X-rays, a method of exposing using synchrotron radiation (SR) (hereinafter referred to as “SR stepper”) has been developed, and it has already been demonstrated that patterns of 100 nm or less can be transferred. .
[0005]
However, a synchrotron radiation light source is effective in mass production of semiconductor devices, but requires large-scale equipment. In order to solve the problem, a method (hereinafter, referred to as a "point source X-ray stepper") has been devised in which a small and powerful X-ray source that can be used for trial production or the like is used as an exposure light source. I have. As an example of a point source X-ray source that generates strong X-rays, a laser source is called a laser plasma source as shown in US Pat. No. 4,896,341. A target is irradiated with a laser to generate plasma, and then the plasma is generated. X-rays to be used.
[0006]
As another example, as shown in Journal of Vacuum Science Technology 19 (4) Nov / Dec 1981 page 1190, X-rays are generated by generating pinch plasma by discharge in a gas. One of the differences from the exposure using synchrotron radiation is that X-rays are emitted in a pulsed manner at any point source X-ray source. Therefore, in order to obtain a desired exposure amount in a single exposure area (one shot), it is necessary to irradiate pulse X-rays a plurality of times.
[0007]
The problem here is that the point source X-ray source has a large output variation of each pulse, and it is difficult to irradiate an accurate exposure amount which is important in lithography. For example, in the case of a pinch plasma discharge, the output variation is said to be 25% at 3σ. Assuming 300 pulses per shot, an exposure error of 0.25% occurs even if the set exposure amount should just reach the set exposure amount in the last shot. It is necessary to reduce the amount of light at the end of the shot to suppress variations. Similarly, in an exposure apparatus that uses an excimer laser that emits pulsed light as a light source, the output can be continuously controlled by the discharge voltage of the excimer laser. However, it is generally difficult to use a point source X-ray source such as a pinch plasma discharge.
[0008]
Conventionally, as means for adjusting (dimming) the energy of the emitted pulse light, a method of inserting an interference filter in the optical path to adjust the transmittance of the pulse light (for example, Japanese Patent Application No. 02731953), an absorbing medium in the optical path, or the like. A method has been proposed in which a chamber filled with a gas to be used is arranged and the transmittance of the pulse light is adjusted by changing the pressure (for example, Japanese Patent Application Laid-Open No. 05-343286).
[0009]
[Problems to be solved by the invention]
These methods have the problems of increasing the cost of the apparatus due to the necessity of means dedicated to light quantity adjustment, securing an occupied place for installing the apparatus, and increasing the occupied volume. These problems, particularly in the case of a point source X-ray exposure apparatus, reduce the maximum X-ray intensity as the exposure path is extended due to the above-mentioned increase in the occupied volume, resulting in a decrease in the throughput of the apparatus.
[0010]
[Means for Solving the Problems]
As an X-ray exposure apparatus, a method of exposing an exposure atmosphere in a chamber sealed with a reduced pressure He in order to suppress attenuation of X-ray intensity is well known. Also, considering the contamination of the light projecting optical system during laser irradiation, etc. F ₂ laser exposure device, so that the atmosphere is controlled with high precision.
[0011]
The present invention provides an X-ray exposure apparatus in which the purity, pressure, and temperature of an exposure atmosphere are originally sufficiently controlled as described above. In this case, the light amount of the emitted pulse light is controlled by changing the light amount, and the light amount can be controlled without extending a light path by adding a new means dedicated to light amount adjustment.
[0012]
In order to achieve the above object, an X-ray exposure apparatus and a method for manufacturing a device according to the present invention are characterized by having the following configuration.
[0013]
That is, an X-ray exposure apparatus that transfers a pattern of an original onto a substrate in a chamber where the exposure atmosphere is controlled,
A light emission control unit that controls a light source for emitting pulsed light,
An intensity monitor for detecting the amount of pulsed light applied to the substrate,
Based on the detected pulse light amount, change the exposure atmosphere of a local region in the chamber, a light amount control unit that controls the light amount of the irradiated pulse light,
It is characterized by having.
[0014]
Preferably, in the above-mentioned X-ray exposure apparatus, the light amount control unit controls the pulse light amount by changing at least one of a rare gas purity and a pressure of the rare gas in a local region through which the pulse light passes in the chamber. I do.
[0015]
Preferably, in the above X-ray exposure apparatus, the intensity monitor section calculates an integration of the pulse light amount,
The light amount control unit calculates a remaining exposure amount based on the total exposure amount and the integrated pulse light amount, and changes an exposure atmosphere of the local region according to the remaining exposure amount.
[0016]
Preferably, in the above X-ray exposure apparatus, the light quantity control unit updates the residual exposure amount for each pulse exposure to change the exposure atmosphere of the local region.
[0017]
Preferably, in the above-mentioned X-ray exposure apparatus, the light quantity control unit controls the rare gas purity of the local region based on the remaining exposure amount, and sets the pulse light transmittance in the local region.
[0018]
Preferably, in the above-described X-ray exposure apparatus, the local area covers an optical path in the chamber over substantially the entire area,
The light quantity control unit changes the exposure atmosphere of the local region to control the light quantity of the irradiated pulse light.
[0019]
Preferably, in the above X-ray exposure apparatus, the exposure atmosphere is a reduced pressure He gas, and the pulsed light is an X-ray.
[0020]
Further, the method for manufacturing a device according to the present invention,
Installing a plurality of semiconductor manufacturing apparatuses in a factory including an X-ray exposure apparatus for transferring an original pattern onto a substrate in a chamber in which an exposure atmosphere is controlled;
Manufacturing a semiconductor device using the plurality of semiconductor manufacturing apparatuses,
And the X-ray exposure apparatus comprises:
A light emission control unit that controls a light source for emitting pulsed light,
An intensity monitor for detecting the amount of pulsed light applied to the substrate,
A light amount control unit configured to change an exposure atmosphere of a local region in the chamber based on the detected pulse light amount and control a light amount of the irradiated pulse light.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0022]
<First embodiment>
<Schematic configuration of apparatus and atmosphere control of chamber (Fig. 1)>
FIG. 1 is a block diagram showing a schematic configuration of a point source X-ray stepper according to an embodiment of the present invention. In FIG. 1, a point source X-ray light source 1 is a plasma X light source that emits X-rays 2 by generating pinch plasma by discharge in, for example, Ne gas. This light source emits X-rays having a peak wavelength of 1.15 nm.
[0023]
The emitted X-rays 2 are guided into the main chamber 3 filled with the reduced pressure He in consideration of the attenuation of the X-rays, and the X-rays are absorbed by the X-ray absorption region (first local region) 4 and the light condensing unit. After passing through a certain collimator 5, an X-ray mask 7 (original, the same applies hereinafter) is irradiated. The pressure, purity, temperature, and the like of He are monitored and controlled by the main chamber atmosphere controller 15 so that the entire main chamber 3 always maintains a constant He atmosphere.
[0024]
Here, the X-ray absorption region 4 is a region surrounded by a member that does not impair X-ray transmission so that the He atmosphere can be locally controlled between the point source X-ray source 1 and the collimator 5. For example, by introducing impurities such as oxygen and nitrogen to lower the He purity, the X-ray transmittance can be lowered, and the X-ray intensity reaching the X-ray mask 7 via the collimator 5 can be reduced.
[0025]
Further, the X-ray transmittance can be lowered by increasing the pressure in the X-ray absorption region 4 instead of lowering the purity. The purity, pressure and the like of the X-ray absorption region 4 are controlled by a local atmosphere control unit 13 which is a sub-control unit of the main chamber atmosphere control unit 15. Although the control targets of the two control units 13 and 15 are the same, the local chamber control unit 13 controls the main chamber atmosphere control unit 15 to always maintain a constant state, whereas the local atmosphere control unit 13 variably specifies the X-ray transmittance. There is a difference in controlling the He atmosphere so that The drawing pattern formed on the X-ray mask 7 is opposed to the X-ray mask 7 with a narrow gap by being irradiated with X-rays, and is transferred onto the resist-coated wafer 8.
[0026]
In order to obtain a desired exposure amount, the required pattern transfer can be achieved by repeating the pulse emission of the point source X-ray light source a plurality of times.
[0027]
<Control of exposure amount (FIGS. 1 and 2)>
Next, the configuration of the exposure amount control will be described with reference to FIG. An X-ray intensity sensor 10 detects the X-ray intensity at each pulse emission, and the information is sent to an intensity monitor 11. The intensity monitor 11 calculates an integrated exposure amount of the corresponding shot based on the X-ray intensity information sensed by the sensor 10. In FIG. 1, the X-ray intensity sensor 10 is disposed between the X-ray mask 7 and the wafer 8, but the information obtained from the X-ray intensity sensor 10 by the intensity monitor 11 is converted into the X-ray intensity on the resist. If converted, the position is not limited to this position, and it can be arranged before and after the collimator 5 or at the X-ray source 1.
[0028]
The main control unit 12 compares the integrated exposure amount obtained by the intensity monitor unit 11 with a desired exposure amount (total exposure amount) of the corresponding shot specified as recipe information from a console (not shown) or the like, and emits the next pulse. Conditions are determined.
[0029]
That is, the main control unit 12 obtains the remaining exposure amount (= desired exposure amount−integrated exposure amount) and, based on the remaining exposure amount, issues a control command for controlling the X intensity in the next pulse emission, the local atmosphere control unit 13, The light emission control unit 14 outputs the light to the main chamber atmosphere control unit 15. The main control unit 12 assumes an average output although there is variation for each pulse. If the remaining exposure amount is equal to or more than N pulses (N: natural number) at the maximum X-ray intensity, the X-ray absorption region 4 Then, the local atmosphere control unit 13 is controlled so that the amount of X-ray transmission at the maximum becomes maximum, and the next pulse emission is instructed to the pulse emission control unit 14.
[0030]
When the remaining exposure amount is smaller than that, that is, when the remaining exposure amount is less than one pulse of the maximum X-ray intensity, the main control unit 12 determines that the X-rays passing through the X-ray absorption region 4 have a desired X-ray intensity (transmittance). The local atmosphere control unit 13 is controlled so that In this control, the main control unit 12 receives the information of the X-ray intensity sensor 10 and the information of the He purity sensor 6 for measuring the He purity of the X-ray absorption region 4 from the intensity monitor 11, and controls the local atmosphere control unit 13. Calculate the amount. Further, the next pulse emission is instructed to the pulse emission control unit 14.
[0031]
FIG. 2 is a diagram showing a schematic relationship between the He purity of the X-ray absorption region 4 and the X-ray transmittance. The He purity range that can be controlled by the local atmosphere controller 13 is from the highest purity “b” to the lowest purity “a”, and the X-ray transmittance is β at the highest and α at the lowest. The main control unit 12 does not perform the control to lower the X-ray intensity by the X-ray transmittance (He purity region C2) lower than the X-ray transmittance “α” corresponding to the minimum purity a. Further, the control for increasing the X-ray intensity by the X-ray transmittance higher than the X-ray transmittance β corresponding to the region C1 exceeding the highest purity b of helium He is not performed. Therefore, in the relationship between the remaining exposure amount and the desired exposure amount, the main control unit 12 determines that even if irradiation is possible at the maximum X-ray intensity (X-ray transmittance β), the remaining exposure amount after the pulse irradiation is The local atmosphere controller 13 is controlled so that the X-ray transmittance does not exceed β and does not become lower than the X-ray transmittance α.
[0032]
<Exposure control process (FIG. 3)>
The above-described exposure amount control process will be described with reference to the flowchart of FIG. In the present embodiment, a known configuration is applied to the transfer and alignment of the wafer and the X-ray mask, and a detailed description is omitted.
[0033]
First, in step S301, the wafer stage 9 is moved and positioned in the XY directions so that the exposure angle of view of the X-ray mask 7 and the next shot area of the wafer 8 to be exposed face each other.
[0034]
Next, in step S302, as the initialization of the one-shot exposure, the set exposure amount (total exposure amount as an initial value) of the recipe information specified via input means such as a console (not shown) is set as the remaining exposure amount of the target shot. I do.
[0035]
In step S303, the main control unit 12 determines whether the X-ray transmittance of the X-ray absorption region 4 is maximized or dimmed at the time of the next pulse emission. Here, “N pulse (N: natural number)” may be a system parameter managed in advance by the main control unit 12 or a job parameter given by recipe information. If it is determined in step S303 that the remaining exposure amount is still sufficiently large (S303-Yes), the process proceeds to step S304, and a control command for controlling the He purity of the X-ray absorption region 4 to the maximum is sent to the local atmosphere control unit. The local atmosphere control unit 13 controls the purity (He purity) of the X-ray absorbing medium based on the control command (S304).
[0036]
If it is determined in step S303 that dimming in the X-ray absorption region 4 is necessary (S303-No), the process proceeds to step S305, where the main control unit 12 determines the current value of the He purity sensor 6 (FIG. The desired purity (He purity) of the X-ray absorbing medium is calculated from the relationship of 2, and is output to the local atmosphere controller 13. The local atmosphere control unit 13 controls the purity (He purity) of the X-ray absorbing medium based on the output to reduce the X-ray intensity (S305).
[0037]
After setting the purity (He purity) of the X-ray absorbing medium controlled in step S304 or S305, in step S306, the main control unit 12 outputs a pulse light emission instruction to the pulse light emission control unit 14, and exposes one pulse. Perform
[0038]
In step S307, the information of the X-ray intensity sensor 10 is read at the timing of exposure, and the value is subtracted from the remaining exposure amount set in step S302 as the current exposure amount, and stored in the intensity monitor unit 11 (update of the remaining exposure amount). ).
[0039]
Next, the value of the remaining exposure amount updated in step S308 is compared with the “permissible remaining exposure amount”. Here, the “allowable remaining exposure amount” can be set by a system parameter managed in advance by the main control unit 12 or a job parameter given by recipe information. As a result of the comparison in step S308, if there is a residual exposure amount larger than the allowable residual exposure amount (S308-Yes), the process returns to step S303, and exposure of the same shot is repeated. Conversely, if the exposure amount is equal to or less than the allowable remaining exposure amount (S308-No), the exposure of the corresponding shot is terminated, and the process proceeds to the exposure of the next shot (step 301). If there is no next shot, the exposure of the wafer is terminated.
[0040]
As described above, according to the present embodiment, in the X-ray exposure apparatus in which the purity, pressure, and temperature of the exposure atmosphere are originally sufficiently controlled, a part of the exposure atmosphere in the optical path is locally changed. This makes it possible to control the exposure amount by making the intensity of the emitted pulse light variable.
[0041]
In addition, it is possible to suppress a decrease in throughput by maintaining the exposure amount without extremely reducing a decrease in X-ray intensity due to an extension of the optical path without adding a new means dedicated to light amount adjustment. be able to.
[0042]
<Embodiment 2 (FIG. 4)>
FIG. 4 is a diagram showing a schematic configuration of a point source X-ray stepper according to the second embodiment of the present invention. 4 is different from the first embodiment in that the whole of the collimator 5 is controlled by the local atmosphere control unit 13 instead of the X-ray absorption area (first local area) 4 (He second high-precision atmosphere control area (second second area)). (Local region) 20.
[0043]
Contrary to the first embodiment, most of the optical paths in the main chamber are covered with the He high-precision atmosphere control unit (second local area) 20, so that the atmosphere in the chamber 3 is not affected by the atmosphere in the optical paths. The pulse light emitted from the light source 1 reaches the mask 7 and the substrate 8. In other words, by configuring a configuration in which most of the optical path in the chamber 3 is covered with the second local region, it is possible to reduce the variation in the light amount for each pulse. The quantity of light to be output can be estimated with high accuracy by statistical processing such as arithmetic averaging and dispersion.
[0044]
According to the present embodiment, it is possible to estimate the light quantity to be output in the next pulse with high accuracy from the light quantity information of several pulses immediately before. The atmosphere in the second local region in the optical path is controlled so that a constant amount of light is irradiated on the mask, and it is possible to suppress the variation in the amount of light for each pulse, thereby facilitating the control of the desired integrated exposure amount.
[0045]
In the first and second embodiments, a point source X-ray exposure apparatus has been described as an example. However, the gist of the present invention is not limited to this, and the present invention is applied to an exposure apparatus that performs exposure in a sealed and controlled exposure atmosphere. Needless to say, the same can be applied to this.
[0046]
<Embodiment of Device Production Method (FIGS. 5 and 6)>
Next, an embodiment of a device production method to which the above-described X-ray exposure apparatus or exposure method is applied will be described.
[0047]
FIG. 5 is a flowchart showing a flow of manufacturing micro devices (semiconductor chips such as ICs and LSIs, liquid crystal panels, CCDs, thin-film magnetic heads, macro machines, etc.). In step S501 (circuit design), a device pattern is designed. In step S502 (mask production), a mask on which the designed pattern is formed is produced. On the other hand, in step S503 (wafer manufacturing), a wafer is manufactured using a material such as silicon or glass.
[0048]
Step S504 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by lithography using the prepared mask and wafer. The next step S505 (assembly) is called a post-process, and is a process of forming a semiconductor chip using the wafer produced in step S504. including. In step S506 (inspection), inspections such as an operation check test and a durability test of the semiconductor device manufactured in step S505 are performed. Through these steps, a semiconductor device is completed and shipped (step S507).
[0049]
FIG. 6 shows a detailed flow of the wafer process. In step S601 (oxidation), the surface of the wafer is oxidized. In step S602 (CVD), an insulating film is formed on the wafer surface. In step S603 (electrode formation), electrodes are formed on the wafer by vapor deposition. In step S604 (ion implantation), ions are implanted into the wafer. In step S605 (resist processing), a photosensitive agent is applied to the wafer.
[0050]
In step S606 (exposure), the circuit pattern of the mask is printed and exposed on the wafer by the above-described X-ray exposure apparatus. In step S607 (developing), the exposed wafer is developed.
[0051]
In step S608 (etching), portions other than the developed resist image are removed. In step S609 (resist removal), unnecessary resist after etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer.
[0052]
In the production method of the present embodiment, if the above-described X-ray exposure apparatus is used, a highly integrated device, which was conventionally difficult to produce, can be produced at low cost.
[0053]
【The invention's effect】
As described above, according to the present invention, in an X-ray exposure apparatus in which the purity, pressure, and temperature of an exposure atmosphere are originally sufficiently controlled, a part of the exposure atmosphere in the optical path is locally changed. It is possible to control the amount of exposure light by making the intensity of the pulsed light emitted in step (1) variable.
[0054]
In addition, it is possible to suppress a decrease in throughput by maintaining the exposure light amount without lowering the cost and reducing the decrease in X-ray intensity due to the extension of the optical path without adding a new means dedicated to light amount adjustment. be able to.
[0055]
In addition, it is possible to estimate the light quantity to be output in the next pulse with high accuracy from the light quantity information of the last several pulses. The atmosphere in the second local region in the optical path is controlled so that a constant amount of light irradiates the mask, it is possible to suppress variations in the amount of light for each pulse, and control of a desired integrated exposure amount is facilitated.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a schematic configuration of an X-ray exposure apparatus according to a first embodiment.
FIG. 2 is a diagram showing a schematic relationship between He purity of an X-ray absorption region 4 and X-ray transmittance.
FIG. 3 is a flowchart illustrating a control process of an exposure amount.
FIG. 4 is a diagram illustrating a schematic configuration of an X-ray exposure apparatus according to a second embodiment.
FIG. 5 is a diagram illustrating a flow of manufacturing a semiconductor device.
FIG. 6 is a diagram illustrating a detailed flow of a wafer process.
[Explanation of symbols]
1: Point source X-ray source 2: X-ray 3: Main chamber 4: X-ray absorption area 5: Collimator 6: He purity sensor 7: X-ray mask 8: Wafer 9: Wafer stage 10: X-ray intensity sensor 11: Intensity Monitor unit 12: Main control unit 13: Local atmosphere control unit 14: Pulse emission control unit 15: Main chamber atmosphere control unit 20: He high precision atmosphere control unit

Claims (8)

In an X-ray exposure apparatus that transfers a pattern of an original to a substrate in a chamber in which an exposure atmosphere is controlled,
A light emission control unit that controls a light source for emitting pulsed light,
An intensity monitor for detecting the amount of pulsed light applied to the substrate,
Based on the detected pulse light amount, change the exposure atmosphere of a local region in the chamber, a light amount control unit that controls the light amount of the irradiated pulse light,
An X-ray exposure apparatus comprising: The method according to claim 1, wherein the light quantity control unit controls the pulse light quantity by changing at least one of a rare gas purity and a pressure of the rare gas in a local region through which the pulse light passes in the chamber. The X-ray exposure apparatus according to claim 1. The intensity monitoring unit calculates an integration of the pulse light amount,
The light amount control unit calculates a remaining exposure amount based on the total exposure amount and the integrated pulse light amount, and changes an exposure atmosphere of the local region according to the remaining exposure amount. Or the X-ray exposure apparatus according to 2. 4. The X-ray exposure apparatus according to claim 1, wherein the light amount control unit updates the remaining exposure amount for each pulse exposure to change an exposure atmosphere of the local region. 5. . 5. The light quantity control unit according to claim 1, wherein a pulse light transmittance in the local region is set by controlling a rare gas purity in the local region based on the remaining exposure amount. 6. Item 10. The X-ray exposure apparatus according to item 1. The local region covers substantially the entire optical path in the chamber,
The X-ray exposure apparatus according to any one of claims 1 to 5, wherein the light quantity control unit changes an exposure atmosphere of the local area to control a light quantity of the irradiated pulse light. . The X-ray exposure apparatus according to claim 1, wherein the exposure atmosphere is a reduced pressure He gas, and the pulse light is X-ray. A method of manufacturing a device, comprising:
Installing a plurality of semiconductor manufacturing apparatuses in a factory including an X-ray exposure apparatus for transferring an original pattern onto a substrate in a chamber in which an exposure atmosphere is controlled;
Manufacturing a semiconductor device using the plurality of semiconductor manufacturing apparatuses,
And the X-ray exposure apparatus comprises:
A light emission control unit that controls a light source for emitting pulsed light,
An intensity monitor for detecting the amount of pulsed light applied to the substrate,
A device for controlling the amount of the irradiated pulse light by changing an exposure atmosphere of a local region in the chamber based on the detected amount of the pulse light, the method comprising: .

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