JPH0345528B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an electron beam transfer apparatus for transferring a pattern of a photoelectric mask onto a sample, such as a semiconductor wafer.

[Technical background of the invention]

The present invention relates to an electron beam transfer apparatus for transferring a pattern of a photoelectric mask onto a sample, such as a semiconductor wafer.

In recent years, with the increasing density of integrated circuits, the limitations of photolithography, which has been the mainstream technology for forming fine patterns, have been pointed out, and new lithography using electron beams and X-rays is rapidly emerging as a way to overcome these limitations. Progress is being made. Recently, photoelectrons emitted by irradiating ultraviolet light onto a photoelectric mask placed parallel to the sample are focused onto the sample using uniform electric and magnetic fields between the sample and the mask, and the pattern on the mask is An electron beam transfer device has been developed that transfers the images onto a sample all at once. This device has high productivity because it is capable of high-speed transfer. Since the mask structure is similar to a photomask, conventional techniques can be used. Since it has a deep depth of focus, it has practical advantages such as being able to transfer onto a substrate with steps, and is extremely promising for processing submicron fine patterns. The effectiveness of such a device has been confirmed, for example, in the literature (R. Ward,
J.Vac.Sci.Technology, 1b(b), Nov/Dec,
(1979).

FIG. 1 is a schematic diagram showing an example of the above-mentioned electron beam transfer device. In the figure, 1 is a vacuum container forming a transfer chamber, and the inside of this container 1 is evacuated to about 10 ^-6 [Torr] by a vacuum pump 2. Inside the vacuum container 1, a sample holding mechanism 4 that holds a sample 3 and a mask holding mechanism 6 that holds a photoelectric mask 5 are provided. The sample 3 and the photoelectric mask 5 are arranged facing each other with a distance of about 10 mm. As shown in an enlarged view in FIG. 2, the photoelectric mask 5 includes a quartz substrate 5a that transmits ultraviolet light, and a mask pattern 5b made of an ultraviolet light absorbing member provided in a desired pattern on the substrate 5a. , and a photocathode 5c made of CsI that emits photoelectrons upon receiving ultraviolet light that reaches the mask pattern 5b without being blocked. Further, the sample 3 has an electron beam-sensitive resist 3a on the surface facing the photoelectric mask 5.
It is coated with The relative positions of the sample 3 and the photoelectric mask 5 are detected by a detector 7, and the positions are aligned based on this detection information.

On the other hand, a light source 8 is provided outside the vacuum container 1 . The light source 8 emits ultraviolet light,
The ultraviolet light is irradiated onto the photoelectric mask 5 through the ultraviolet light transmitting window 10 when the shutter 9 is opened. Furthermore, a Helmholtz coil 11 and a DC power source 12 are provided outside the vacuum vessel 1, respectively. A magnetic field is applied by the coil 11 along the direction in which the sample 3 and the mask 5 face each other, and an electric field is applied by the power source 12 in the same direction as the above direction. In addition, in the figure, 13, 14, and 15 indicate a surface plate, reinforced rubber, and a pedestal, respectively.

When the photoelectric mask 5 is irradiated with ultraviolet light from the light source 8, photoelectrons corresponding to the mask pattern 5b are emitted from the mask 5, and these photoelectrons are focused by the magnetic field and electric field and irradiated onto the sample 3. . As a result, the resist 3a on the sample 3
is exposed according to the mask pattern 5b. In this way, mask pattern 5b is transferred to sample 3.
It can be transferred all at once, and has the advantages mentioned above.

[Problems with background technology]

However, this type of device has the following problems. That is, when the pattern transfer is completed, it is necessary to replace the sample 3, but each time the sample 3 is replaced, the inside of the vacuum container 1 is opened to the atmosphere.
The photoelectric mask 5 deteriorates significantly due to moisture absorption. Furthermore, it is necessary to thermally adhere CsI or the like to the surface of the photoelectric mask 5 every time approximately 50 patterns are transferred, and a significant decrease in productivity cannot be avoided. moreover,
When replacing the sample 3 or the photoelectric mask 5, it is necessary to manually remove the sample table 2 or the mask table 4 from the transfer chamber 1, which causes a reduction in transfer accuracy due to the effects of dust, temperature changes, etc. There's a problem.

[Purpose of the invention]

This invention was devised to solve the above problems, and it is not necessary to open the sample chamber to the atmosphere every time a sample is exchanged, making it possible to significantly improve productivity, and to prevent dust, temperature changes, etc. It is an object of the present invention to provide an electron beam transfer device that can prevent the influence from occurring.

[Summary of the invention]

In the electron beam transfer apparatus according to the present invention, first and second sample preparation chambers communicate with a transfer chamber of a vacuum container, and a sample is supplied from the outside to the first sample preparation chamber while maintaining a vacuum, and a pattern is The sample onto which has been transferred is taken out from the second sample preparation chamber while maintaining a vacuum outside. For this reason, the vacuum in the transfer chamber is not broken for sample supply and removal. Further, the sample is transported from the first sample preparation chamber to the transfer chamber by the first transport mechanism, and the sample with the pattern transferred is transferred from the transfer chamber to the second sample preparation chamber by the second transport mechanism. The sample is then transported and aligned on the orientation flat in the first sample preparation chamber. Some of these operations can be performed almost simultaneously with the transfer operation, resulting in excellent workability.

Further, in the present invention, a sample whose orientation flat is aligned in the first sample preparation chamber is supported by an electrostatic chuck on a support stand in the preparation chamber, and is further electrostatically chucked by the first transport mechanism. The sample is then transported onto the sample stage inside the transfer chamber. Therefore, the sample can be set on the sample stage with the orientation flats aligned without causing the sample to be misaligned during standby in the first preliminary chamber and during transport in the first transport mechanism. . This is an extremely large advantage for a transfer device in which the sample cannot be moved significantly within the transfer chamber.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An electron beam transfer apparatus according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

In FIGS. 3 and 4, reference numeral 20 designates a cylindrical vacuum container having a transfer chamber therein, which is vertically installed so that an ultraviolet transmitting window 21 formed on one end surface faces upward. First and second protrusions 22 and 23 are formed at mutually opposing portions of the peripheral wall of the vacuum container 20, and these protrusions communicate with the transfer chamber and are coaxially arranged in opposite directions. The first wafer preparatory chamber 22a and the second wafer preparatory chamber 22a extend to
A wafer preliminary chamber 23a is formed. The preliminary chamber and the transfer chamber constitute a main chamber. In addition, a vacuum pump 24 is connected to the transfer chamber, and this pump operates the transfer chamber and the preliminary chamber.
It is exhausted to about 10 ^-6 Torr.

Inside the transfer chamber, there are a sample stage 26 for fixedly holding a sample (wafer) 25 with its electron beam sensitive resist layer side facing up, and a mask support mechanism 28 for fixedly holding a photoelectric mask 27 with its mask pattern side facing down. It is provided. These sample stage 26 and mask support mechanism 28 are constituted by an XYZθφ-table, and it is possible to position the sample 25 and photoelectric mask 27 at arbitrary positions with high precision. Reference numeral 29 indicates a detection mechanism for detecting the position of the sample 25, and the position of the sample 25 is adjusted according to a signal from this.

An opening 30 is formed in a portion of the upper wall of the first protrusion 22.
is formed. This opening 30 is connected to the protrusion 22
It is closed by a first moving body 31 whose lower end is in contact with the outer surface of the upper wall. A subchamber 32 is formed in the first moving body 31 so as to communicate with the first wafer preparatory chamber 22a of the protrusion 22 through the opening 30. A pneumatic or hydraulic cylinder 34 supported by a support 33 is provided above the movable body 31, and the lower end of the piston of the pneumatic or hydraulic cylinder 34 is connected to the movable body 31. Thus, the moving body 33 can be moved in the vertical direction by the hydraulic cylinder 34, and when moved upward, the opening 30 is exposed to the outside.

An opening is formed in a portion of the lower wall of the first protrusion 22 so as to face the opening 30, and a support base 35 is protruded from below in this opening while maintaining airtightness. A drive mechanism 37 is provided on a shaft 36 that protrudes from the lower end of this support base 35 . This drive mechanism 37 moves the support base 35 in the vertical direction via a shaft 36, and is composed of, for example, bolts, screws, and a motor. The upper surface of the support stand 35 is formed flat and has an electrostatic chuck 38 capable of adsorbing the sample 25, as shown in FIG. A flange 39 is provided on the outer peripheral surface near the top surface of the support base 35, and a mechanical seal (Wilson seal) formed of ring-shaped rubber is provided on the top surface of the flange 39.
40 are provided respectively. When the support base 35 is moved upward, the mechanical seal 40 comes into contact with the inner surface of the upper wall of the protrusion 22 so as to surround the opening 30, and the flange portion 39 closes the opening 30 from the inside. That is, the first wafer preliminary chamber 22a
Communication between the subchamber 32 and the subchamber 32 is closed by a flange 39. In FIG. 5, reference numeral 41 indicates the protrusion 22.
The O-ring provided on the upper wall of the moving body 3 is shown.
1, thereby making the subchamber 32 more securely cut from the outside. In this way, the first sample supply mechanism 42 is configured, and this mechanism supplies the sample (wafer) to the first wafer preliminary chamber 2.
2a from the outside in an airtight manner.

In the first wafer preparation chamber 22a, there is a transport mechanism 4 for guiding a sample supplied from the outside onto the sample stage 26.
3 is provided. This conveyance mechanism 43
As shown in the figure, it has a plate-shaped transport arm 44,
The arm 44 is movably provided in the first wafer preparatory chamber 22a by a pair of support rails 45 extending horizontally along the side walls of the first wafer preparatory chamber 22a. Further, a bearing 46 is attached to one side wall of the protruding end of the first protruding portion 22.
A shaft 47 is rotatably supported by this bearing 46, with both ends protruding from the side walls. Note that the bearing 46 and shaft 47 are set so that the first wafer preliminary chamber 22a can be maintained in a vacuum. A pulley 48 is fixed to one end of the shaft 47 protruding into the first wafer preparatory chamber 22a, and an endless belt 49 is connected between the pulley 48 and a pulley (not shown) provided in the vacuum container. is being passed over. One end of the arm 44 is attached to the endless belt 49. Further, a first gear 50 is provided at the other end of the shaft 47 located outside the protrusion 22.
is fixed. This gear 50 has a protrusion 22
It is meshed with a second gear 51 fixed to a rotating shaft of a motor 52 provided externally.

Thus, by driving the motor 52, the arm 4
4 is reciprocated between the subchamber 32 and the sample stage 26 via a gear train and an endless belt 49. A limit switch is provided so that the arm 44 stops at a predetermined position with respect to the subchamber 32 and the sample stage 26, and when the moving arm 44 closes this switch, the drive of the motor 52 is stopped. Ru. In Figure 6, code 53
indicates an electrostatic chuck provided on the arm 44;
The sample 53 is suctioned and held by this chuck.
It is transferred by arm 44. Note that, as shown in FIG. 4, a vacuum pump 92 is connected to the subchamber 32 for evacuating the chamber.

The first supply mechanism 42 supplies the sample 25 from the outside into the first wafer preliminary chamber 22a, and the transport mechanism 4
3 has the function of guiding the sample 25 onto the sample stage 26. A supply mechanism 42 having substantially the same configuration as these
A transport mechanism 43 is also provided in the second wafer preliminary chamber 23a. This transport mechanism transports the patterned sample to the second wafer preliminary chamber 23a,
The supply mechanism functions to send the transported sample to the outside.

On the side of the first protrusion is an index station 54 that accommodates a wafer as a sample.
A second supply mechanism 55 for guiding the wafer from the station 54 to the electrostatic chuck 38 of the support table 35 is provided as shown in FIG.

The index station 54 has a wafer carrier 56 that stores 25 wafers in one lot at predetermined intervals in the vertical direction. The wafer is fixed on a wafer carrier table 59. Further, a feed screw 60 is rotatably provided parallel to the support column 58, and this screw 60 is connected to the support column 58.
It is supported by a guide bearing 61 provided at 8, and is also screwed into a support base 57. A rotating shaft of a motor 62 is connected to the feed screw 60. Thus, the feed screw 60 is rotated by the drive of the motor 62, and the support stand 57, ie, the wafer carrier 56, is moved up and down.

The second supply device 55 has a base 63,
A supporting column 64 that can be expanded and contracted in the vertical direction is provided protruding from this. A rotating arm 65 is rotatably attached to the upper end of this support column 64, and furthermore, a supporting arm 65 is attached to the rotating arm 65 so as to be extendable and retractable in the horizontal direction.
6 is provided. Further, in the base 63 there is a drive mechanism that moves the support column 64 in the vertical direction, in the support column 64 there is a drive mechanism that rotates the rotation arm 65 by 90 degrees, and in the rotation arm 65 there is a drive mechanism that moves the support column 64 in the vertical direction. A drive mechanism is provided to extend and retract the respective parts. A vacuum chuck 67 is provided on the top surface of the tip of the support arm 66. Thus, as shown in FIG. 7, with support arm 66 facing wafer carrier 56, arm 66 is extended so that its vacuum chuck 67 is positioned below a given wafer within carrier 56. Then, in this state, the carrier 56 is moved downward and the wafer is attracted to the vacuum chuck 67. After this, the support arm 66 is moved back to its original position and rotated through 90 degrees. The position of the wafer when it rotates is
It is set to coincide with the electrostatic chuck 38 of the support base 35.

In the apparatus of this embodiment, when the wafer is placed on the support stand 35 and is waiting in the first wafer preparation chamber 22a, the orientation flat of the wafer is set at a predetermined position. A positioning mechanism 68 for this purpose is provided as shown in FIG. This mechanism 68 is installed in the first wafer preparatory chamber and has four horizontally movable drive rollers 69, 70, 71, and 72. Each roller has four motors 73, 74, 75, 76.
A rotating shaft is directly connected to the motor, and the motor rotates the motor. The third and fourth drive rollers 71, 72 are provided close to each other, and these drive rollers 71,
72, the first and second drive rollers 6
9 and 70 are provided at approximately equal intervals.
A support stand 77 is provided near the third and fourth drive rolls 71 and 72, and this support stand 77
Third and fourth drive rollers 7 are provided on the lower surface of the extension.
A pair of light emitting elements 78 are provided between the light emitting elements 1 and 72 at a predetermined distance from each other.
These light-emitting elements 78 are located above the circumference of the wafer (sample) 25, and one light-emitting element 78 is located below the circumference of the wafer 25 in correspondence with these light-emitting elements 78.
A pair of light receiving elements 79 is provided. When the light from the light emitting element 78 is incident on both of these light receiving elements 79, the four motors 73, 74,
A switch circuit is connected to stop the driving of 75 and 76. The positioning mechanism 68 having such a structure is operated as follows after the wafer 25 is held at the standby position and the electrostatic chuck 38 that was holding the wafer 25 is released from the holding operation. First, the four drive rollers 69, 7
0, 71, 72 are moved horizontally from the outside,
They are brought into contact with the outer peripheral end surface of the wafer 25 and simultaneously rotated in the same direction by their respective motors. As a result, the wafer 25 is rotated in the opposite direction to the drive roller. As shown in FIGS. 9 and 10, when the orientation flat of the wafer reaches a predetermined position, the light from the light emitting element 78 that has been blocked by the circumference of the wafer passes through the orientation flat to the light receiving element 79. light is received. As a result, the signal from the light receiving element 79 causes the drive of the motor and thus the rotation of the drive roller to be stopped.
Therefore, the rotation of the wafer 25 is stopped and the wafer 25 is set at a predetermined position. Thereafter, the wafer 25 is attracted by the electrostatic chuck 38, and the drive roller is separated from the wafer to stand by at its original position.

As shown in FIG. 4, a mask supply mechanism 80 is connected to the vacuum container 20 at an angle of about 90 degrees to the protrusions 22 and 23. This supply mechanism 80 stores a plurality of photoelectric masks 27 in advance, and supplies them one by one to the mask holding mechanism 28 (FIG. 3) inside the vacuum container 20 as needed. It is structured as shown. 1st
In FIG. 1, reference numeral 81 indicates a mask preliminary chamber, which is connected to the vacuum chamber 20 via a gate valve 82. In this preliminary chamber 81, there is an optical mask 27.
A photoelectric mask cassette magazine 83 is housed in which the photoelectric mask cassettes are held at a predetermined distance from each other in the vertical direction. This magazine 83 is fixed to the upper end of a vertically provided support column 84.
The lower end of the preliminary chamber 81 extends downward from the lower wall. The lower end is connected to means for moving the support column 84 in the vertical direction, such as a piston of an air cylinder 85. Further, the middle part of the support column 84 is attached to a bellows 86 provided on the lower wall of the preliminary chamber 81, and thus the cassette magazine 83 is moved by an air or hydraulic cylinder 85 while maintaining the vacuum in the preliminary chamber 81. can be moved up and down. A mask transport mechanism 87 is provided in the horizontal protrusion 81 a of the preliminary chamber 81 . This mechanism 8
7 has a transport arm 88 provided within the protrusion 81a so as to be movable in the horizontal direction. A rack is formed on the side surface of this transfer arm 88, and this rack is engaged with a pinion fixed to the tip of the rotating shaft of a DC-motor 89, so that the arm 88 is horizontally moved when the motor 89 is driven. direction. This motor 89 is provided outside the protrusion 81a, and the rotation shaft is connected to the protrusion 81a through an airtight bearing 90 provided on the upper wall of the protrusion 81a.
It is extended inside. In such a supply mechanism 80, from the state shown in FIG. 11, the motor 89 is driven to move the arm 88 forward so that its tip is located in the cassette magazine 83, and then
The air cylinder 85 is driven to move the magazine 83 slightly downward. As a result, a predetermined photoelectric mask 27 in the magazine 83 is placed on the tip of the arm 88. In this state, the motor 89 is driven again to move the arm 88 further forward, and the photoelectric mask 2
7 is located at the mask support mechanism within the vacuum vessel 20 via the gate valve 82. When removing an unnecessary photoelectric mask from the mask support mechanism,
By reversing the operation, the arm 88 transports the cassette from the support mechanism to the cassette magazine 83. In addition,
In FIG. 11, reference numeral 91 indicates a vacuum pump for evacuating the mask preliminary chamber 81.

In the apparatus of the above-described embodiment, parts that are substantially the same as those of the prior art and that are not related to the gist of the invention are designated by the same reference numerals as shown in FIG. 1, and explanations thereof will be omitted.

The operation of the electron beam transfer device having the above configuration will be explained below.

First, a predetermined photoelectric mask 27 is transported from the photoelectric mask cassette magazine 83 to the transfer chamber by the transport arm 88, and then this mask is supported by the mask support mechanism 28. Meanwhile, the sample (wafer) 25 is transferred from the wafer carrier 56 to the first wafer preliminary chamber 22a.
It is adsorbed onto the electrostatic chuck 38 of the support stand 35 provided on the side. At this time, the electrostatic chuck 38 has already been moved to the upper position as shown in FIG. is exposed to the outside at the opening 30, making it possible to place the sample 25 thereon. When the sample 25 is attracted onto the electrostatic chuck 38, the movable body 31 is lowered to the lower position shown in FIG. 5, making the subchamber 32 airtight. This subchamber 32 is evacuated by the vacuum pump 92, and then the support table 35 is moved to a lower position, that is, until the sample 25 is at a predetermined position in the first wafer preliminary chamber 22a. After the sample 25 is positioned at this position by the positioning mechanism 68, it is moved onto the sample stage 26 by the transport mechanism 43 and adsorbed thereon. At this time, the converging magnet 11 is energized to generate a magnetic field along the direction in which the sample 25 and the photoelectric mask 27 face each other, and an electric field is applied by the power source 12 in the same direction as this magnetic field. This sample stage 2
6, the sample 25 is set at a predetermined position relative to the photoelectric mask 27 by moving the sample stage 26 while its position is detected by the detection mechanism 29. After positioning the photoelectric mask 27 and the sample 25 in this manner, the shutter 9 is opened and the photoelectric mask 27 is irradiated with ultraviolet light emitted from the light source 8 through the ultraviolet transmission window 21. As a result, photoelectric mask 2
Photoelectrons corresponding to the mask pattern are emitted from 7, and the photoelectrons are focused by the magnetic field and electric field and irradiated onto the sample 25. As a result, the resist on the sample 25 is exposed according to the mask pattern, and the pattern is transferred onto the sample 25. The transferred sample 25 is conveyed into the second wafer preliminary chamber 23a by a conveyance mechanism 43 provided on the second wafer preliminary chamber 23a side, and is led out from there via a supply mechanism 42. Note that the sample extraction process at this time is performed in parallel with the next sample supply process.

In the above embodiment, the first and second sample preparation chambers are separated from each other by 180 degrees and communicated with the transfer chamber. It may be provided.
The mechanism for supplying the sample from the outside and the mechanism for taking out the sample to the outside are not limited to an elevator mechanism that moves the sample in the vertical direction; for example, a mechanism that moves the sample in the horizontal direction may be used, but it is necessary to maintain the vacuum in the sample preparation chamber. It is necessary to do so.

〔Effect of the invention〕

As described above, in the electron beam transfer apparatus according to the present invention, it is possible to prevent the sample from deteriorating due to moisture absorption or the like caused by opening the transfer chamber to the atmosphere. In addition, continuous work is possible, and some work can be done overlapping times, resulting in good work efficiency and excellent mass production.

[Brief explanation of drawings]

FIG. 1 is a diagram schematically showing a conventional electron beam transfer device, FIG. 2 is a diagram for explaining the operation of transferring a pattern of a photoelectric mask onto a wafer, and FIG.
11 to 11 show an electron beam transfer device according to an embodiment of the present invention, FIG. 3 is an overall sectional view, FIG. 4 is an overall plan view, and FIG. 5 is a sectional view showing a sample supply mechanism. , FIG. 6 is a plan view showing the sample transport mechanism, FIG. 7 is a side view showing the mechanism for supplying wafers to the subchamber and the index station, FIG. 8 is a perspective view showing the positioning mechanism, and FIGS. 10 is a plan view and a side view showing the relationship between the positioning mechanism and the orientation flat of the wafer, and FIG. 11 is a sectional view showing the mask supply mechanism. 20... Vacuum container, 22a... First wafer preliminary chamber, 23a... Second wafer preliminary chamber, 25... Sample, 26... Sample stage, 27... Photoelectric mask, 28
...Mask support mechanism, 42...Sample supply mechanism, 4
3... Conveyance mechanism.

Claims (1)

[Scope of Claims] 1. A vacuum container in which a transfer chamber is formed, a sample stage provided in the transfer chamber for fixing and holding a sample, and a photoelectric mask provided in the transfer chamber for holding a photoelectric mask facing the sample. a means for relative positioning of the sample and the mask; a means for applying a magnetic field and an electric field along the direction in which the sample and the photoelectric mask face each other; The second sample preparatory chamber and the first sample preparatory chamber are provided with a mechanism for supplying the sample from the outside onto the internal support stand while maintaining the vacuum in the preparatory chamber, and an orienting mechanism for the sample supplied into the preparatory chamber. a first transport mechanism that transports the sample from the first preparation chamber to the sample stage; and a second transport mechanism that transports the sample with the pattern transferred to the second sample preparation chamber. a mechanism for extracting the sample from the second sample preparatory chamber to the outside while maintaining the vacuum in the preparatory chamber, and a mechanism for removing the sample from the second sample preparatory chamber to the outside while maintaining the vacuum in the transfer chamber; The support stand of the first preliminary chamber is provided with an electrostatic chuck mechanism on the sample mounting surface, and the sample aligned on the orientation flat is moved by an electrostatic force. The first transport mechanism is provided with an electrostatic chuck mechanism at the tip of the transport arm,
An electron beam transfer device characterized by transporting a sample while being fixed by electrostatic force.