JP2649556B2 - Mask holding device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mask holding apparatus used in a transfer step in a lithography step for manufacturing a highly integrated semiconductor circuit element, and particularly to an X-ray exposure apparatus. And a suitable mask holding device.

[Prior Art] Conventionally, as a mask holding device in an exposure apparatus, there have been used a vacuum holding method and a magnetic suction method. There are two types of magnetically-attached mask holding devices that use an electromagnet, and those that use a permanent magnet and an electromagnet.

FIG. 4 shows a cross section of a mask holding device using an electromagnetic force. This type of device is, for example, one disclosed in Japanese Patent Application Laid-Open No. Sho 60-77434. In the figure, 1
Is a mask frame at least partially made of a magnetic material, 2 is a membrane, 3 is an absorber, 6 is a solenoid coil for generating lines of magnetic force, 4 is a yoke (mask holder) for forming a magnetic path, 7 Is a lead wire for supplying electricity to the solenoid coil, and 11 is a cooling water pipe for removing heat generated from the solenoid coil 6 to the outside.

When the solenoid coil 6 is energized while the mask frame 1 is in contact with the mask holder 4 in the state shown in FIG. 2, the mask holder 4 is excited, and the mask frame 1 is magnetically attracted and held by the mask holder 4. Next, when power is turned off,
The mask frame 1 comes off the mask holder 4.

FIG. 3 shows a cross section of a mask holding device using the magnetic force of a permanent magnet. This type of apparatus is disclosed in, for example,
It is disclosed in, for example, Japanese Patent No. 216227. In the figure, 1 is a mask frame, 5 is a ring-shaped permanent magnet, 6a and 6b are solenoid coils wound in a ring shape, 4 is a mask holder for forming a magnetic path, and 7 is a solenoid coil 6a and 6b.
This is a lead wire for supplying current to the power supply. In the configuration shown in the figure, the magnetic flux emitted from the permanent magnet 5 passes through the mask frame 1 and circulates through the mask holder 4 to the lower surface of the permanent magnet 5, thereby holding the mask frame 1 by suction.
Next, when magnetic fluxes temporarily canceling the magnetic flux of the permanent magnets 5 are generated by the solenoid coils 6a and 6b, the attraction force between the mask holder 4 and the mask frame 1 is lost and the mask frame 1 comes off.

[Problems to be Solved by the Invention] However, in each of the above-described conventional examples, since an electromagnet is used in any case, a short-circuit or disconnection of a solenoid coil, an abnormality in a power supply for supplying current to the solenoid coil, and a solenoid coil No countermeasure was taken against the abnormality of CPU giving ON / OFF signal.

Therefore, when the mask is replaced, the current is supplied to the solenoid coil when the mask is suction-held on the mask holding device, and the current is not supplied to the solenoid coil when the mask is not sucked or removed from the mask holding device. There was a problem that it was in a state and could not leave.

Further, in the case where irradiation energy such as SOR light (synchrotron radiation light) is used as the X-ray source and the mask is irradiated in the horizontal direction with respect to the horizon, the mask must be held upright. For this reason, when the above trouble occurs, there arises a problem that the mask is dropped or the mask is not replaced while maintaining the suction state on the mask holding device.

In view of the above-described problems of the conventional type, the present invention provides an X-ray exposure apparatus that requires an extremely fine and highly accurate transfer mask to be held in a special environment such as a reduced pressure helium gas, a nitrogen gas, or a vacuum. However, an object of the present invention is to provide a mask holding device capable of holding and releasing a mask with extremely high reliability.

[Means and Actions for Solving the Problems] In order to achieve the above object, a mask holding device according to the present invention includes a permanent magnet that generates a magnetic force for attracting a mask, and a magnetic flux formed by the permanent magnet. In order to generate a magnetic flux that temporarily cancels out, a first and a second solenoid coils respectively wound around the permanent magnets, and a power supply for supplying an exciting current to the first and the second solenoid coils are provided. The mask suction force in a state where both the first and second solenoid coils operate normally and the mask suction force in a state where only one of the first and second solenoid coils operates normally are close to each other. In addition, the magnetic force generated by the permanent magnet and each solenoid coil is set or the current of each solenoid coil is controlled.

As a result, the device relating to the solenoid coil that generates the reverse magnetic flux with respect to the time flux formed by the permanent magnets is provided with redundancy, and a stable mask adsorption and desorption operation can be realized.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a sectional view of a mask holding device according to a first embodiment of the present invention. In the figure, 1 is a mask frame made of a magnetic material, 2 is a membrane for forming a circuit pattern on the mask frame 1, 3 is an absorber for absorbing irradiation energy, and 4 is a mask for forming a magnetic circuit. Holder 5 is an annular permanent magnet (polarized in the vertical direction), 6a and 6b are solenoid coils wound around the inside and outside of permanent magnet 5, and 7a and 7b supply current to solenoid coils 6a and 6b. Lead wires for supply, 8a and 8b are power supplies for supplying current to the solenoid coils 6a and 6b, and 9 is a CPU for giving ON / OFF signals to the solenoid coils 6a and 6b.

The magnetic flux emitted from the upper surface of the permanent magnet 5 circulates through the mask holder 4 to the lower surface of the permanent magnet 5. In addition, the solenoid magnets 6a and 6b are used alone as electromagnets (in the opposite direction to the permanent magnet attraction force) with respect to the attraction force of the permanent magnet 5.
By setting the suction force at an appropriate ratio, it is possible to cope with an abnormality in one of the solenoid coils. For example, if the attraction force of the permanent magnet 5 is 100 and the attraction force of the solenoid coils 6a and 6b is 65 and 65, respectively, the force required for normal detachment is 30 (the attraction force 130 of the two solenoid coils 6a and 6b combined). And permanent magnet 5
The force required for detachment in the event of a failure is 35 (the difference between the attraction force 65 of one of the solenoid coils 6a and 6b and the attraction force 100 of the permanent magnet 5). Therefore, even if there is some abnormality in one of the systems of the solenoid coils 6a and 6b, the operation of holding and removing the mask can be stably performed.

In the above structure, the mask frame 1 is
, A magnetic circuit is formed by the permanent magnet 5, the mask holder 4 and the mask frame 1, and the mask frame 1 is attracted to and absorbed by the permanent magnet 5 and the mask holder 4. At the time of separation, power is supplied to the solenoids 6a and 6b from the power supplies 8a and 8b via the lead wires 7a and 7b so that magnetic flux opposite to the magnetic flux of the permanent magnet 5 is generated, thereby temporarily canceling the magnetic force. Perform the detaching operation. In this case, if the power supply has a self-diagnosis function (not shown) and can supply current without malfunction, if the coil has the above-described coil attracting force, the normal operation, at the time of failure, and stable operation from the CPU 9 in any case. Can be ordered. It is sufficient that the number of solenoid coils is two or more, and it is preferable that the number of power supplies is two or more.

FIG. 2 shows a configuration of a mask holding device according to a second embodiment of the present invention.

In the second embodiment, the solenoid coils 6a and 6b are driven by two power supplies 8a and 8b as in FIG. 1, but other than that, the solenoid coil abnormality detection for detecting disconnection and short circuit of the solenoid coils 6a and 6b CPUs 11a and 11b are arranged corresponding to the units 10a and 10b and the solenoid coils 6a and 6b.
Further, a CPU 9 for controlling these two CPUs is provided.

In the above configuration, when performing the detaching operation, an excitation current is supplied to each of the solenoid coils 6a and 6b so that the attraction force is half of the attraction force of the permanent magnet 5. Thereby, the force required for detachment becomes almost zero.

Further, for example, when the solenoid coil 6a is short-circuited or disconnected, first, the solenoid coil abnormality detection unit 10a detects this. This abnormality is transmitted to the CPU 9 through the CPU 11a. CPU 9 receives this signal, and after that, the solenoid coil
The exciting current is controlled so that the detaching operation can be performed only by 6b. That is, at the time of the detaching operation, a current that allows the detaching operation to be supplied to the solenoid coil 6b through the CPU 11b.

Although not shown in FIG.
The power supply has a self-diagnosis function.

Various variations are conceivable for the type and number of permanent magnets, the type and number of solenoid coils, and the number of CPUs and power supplies, but only two representative embodiments have been described here.

[Effects of the Invention] As described above, according to the present invention, by setting the attraction force of the solenoid coil at a certain ratio with respect to the attraction force of the permanent magnet, stable operation can be performed even when the solenoid coil fails. Can be performed.

If an abnormality detection unit, CPU, and power supply are arranged for each solenoid coil, not only stable operation can be performed during normal operation and during failure, but also the force required for detachment can be set to a variable value from zero. it can.

[Brief description of the drawings]

FIG. 1 is a sectional view of a mask holding device according to a first embodiment of the present invention, FIG. 2 is a sectional view of a mask holding device according to a second embodiment of the present invention, FIG. FIG. 4 is a sectional view of a conventional mask holding device using magnetic force. 1: mask frame, 2: membrane, 3: absorber, 4: mask holder, 5: permanent magnet, 6,6a, 6b: solenoid, 7,7a, 7b: lead wire, 8a, 8b: power supply, 9,11a , 11b: CPU, 10a, 10b: solenoid coil abnormality detector, 12: cooling water pipe.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takuo Kariya 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Isamu 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon (56) References JP-A-60-251621 (JP, A) JP-A-59-159505 (JP, A) Jpn.

Claims (2)

(57) [Claims] 1. An apparatus for holding a mask in an exposure apparatus for transferring a pattern formed on the mask onto a wafer, comprising: a permanent magnet for generating a magnetic force for attracting the mask; and a permanent magnet formed by the permanent magnet. First and second solenoid coils respectively wound around the same permanent magnet for generating a magnetic flux for temporarily canceling the magnetic flux, and an exciting current is supplied to the first and second solenoid coils. And a power supply, wherein the mask attraction force in a state where both the first and second solenoid coils operate normally and the mask attraction force in a state where only one of the first and second solenoid coils operates normally. A mask holding device, wherein the generated magnetic forces of the permanent magnet and each of the solenoid coils are set to be close values. 2. An apparatus for holding a mask in an exposure apparatus for transferring a pattern formed on the mask onto a wafer, the permanent magnet being formed by a permanent magnet for generating a magnetic force for attracting the mask. First and second solenoid coils respectively wound around the same permanent magnet for generating a magnetic flux for temporarily canceling the magnetic flux, and an exciting current is supplied to the first and second solenoid coils. A power supply, and a mask attraction force in a state where both the first and second solenoid coils operate normally based on the abnormality detection information, detecting abnormality in each of the first and second solenoid coils; Control means for controlling an exciting current supplied to each solenoid coil such that the mask attraction force in a state where only one of the first and second solenoid coils operates normally has a value close to the value. Mask holding device to.