JP6711661B2 - Holding apparatus, holding method, lithographic apparatus, and article manufacturing method - Google Patents

Description

The present invention relates to a holding device, a holding method, a lithographic apparatus, and a method for manufacturing an article.

When holding a substrate used in a lithographic apparatus for manufacturing a semiconductor device or the like, there is a demand for a technique for holding a substrate that is largely warped or deformed with good flatness. As a method of holding the substrate, there is a method of vacuum suctioning the back surface of the substrate. In this method, the suction air may leak due to the warp of the substrate or the like and the suction may not be sufficiently performed. To solve this problem, there is a technique of dividing the suction area and adjusting the suction timing by the divided suction areas (Patent Documents 1 and 2).

JP, 2015-38982, A JP, 11-067882, A

However, in the technique of Patent Document 1, the suction timing is adjusted while measuring the flatness of the substrate, and in the technique of Patent Document 2, the substrate is radially attracted from the center. The former requires an additional configuration for measuring flatness, and the latter may be difficult to deal with a substrate having a complicated warp.

The present invention aims to provide a holding device that is advantageous for holding a substrate with good flatness, for example.

In order to solve the above problems, the present invention is a holding device for holding a substrate by vacuum suction, the first suction unit having a plurality of suction regions, the second suction unit having a plurality of suction regions , based on the pressure when adsorbed by the first adsorbing portion board, the second to determine the order in which to start the suction of the substrate by a plurality of retaining regions in the adsorption unit, the second adsorption unit follow the order in start the plurality of adsorption of the adsorption region, to have a, and a control unit for adsorbing the substrate by the second adsorption unit, characterized in that.

According to the present invention, for example, it is possible to provide a holding device that is advantageous for holding a substrate with good flatness.

It is a schematic diagram of an exposure apparatus provided with a holding device concerning a 1st embodiment. It is the figure which looked at the adsorption part from the upper part. It is a figure which shows the whole holding|maintenance apparatus containing the adsorption|suction part of FIG. 2(A). It is a figure which shows the state in which the board|substrate of the warp was carried in to the adsorption|suction part. It is a figure which shows the state in which the board|substrate of the warp was carried in to the adsorption|suction part. 3 is a flowchart of a vacuum suction method according to the first embodiment.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic view of an exposure apparatus including a holding device according to the first embodiment of the present invention. The holding apparatus can be applied to other lithographic apparatus (for example, imprint apparatus), but in the present embodiment, application to an exposure apparatus will be described as an example. The exposure apparatus including the holding device according to this embodiment includes a light source 110, an illumination optical system 120, a projection optical system 130, a stage 140, and a control unit 150. In addition, the holding device according to the present embodiment includes a suction unit 160 and a suction control unit 170. The optical axis of the projection optical system 130 is the Z axis, and the plane perpendicular to the Z axis is the XY plane.

The light source 110 outputs light in a plurality of wavelength bands as exposure light. The illumination optical system 120 includes a light shielding plate 121, a half mirror 122, a photo sensor 123, a mirror 124, a shaping optical system (not shown), and an optical integrator (not shown). The light emitted from the light source 110 is shaped into a predetermined beam shape via the shaping optical system of the illumination optical system 120, and the shaped beam is incident on the optical integrator. The optical integrator forms a large number of secondary light sources that illuminate the reticle (original plate) R with a uniform illuminance distribution. The reticle R is also called a mask and has a circuit pattern of a semiconductor device to be printed on its surface. The light blocking plate 121 is arranged on the optical path of the illumination optical system 120, and forms an arbitrary illumination area on the reticle R. The half mirror 122 is arranged on the optical path of the illumination optical system 120, and reflects and extracts a part of the exposure light that illuminates the reticle R. The photo sensor 123 is arranged on the optical path of the reflected light of the half mirror 122, and outputs a signal corresponding to the intensity (exposure energy) of the exposure light to the illumination optical system controller 151. The illumination optical system controller 151 controls the light blocking plate 121 and the like based on the output.

The projection optical system 130 is of a refraction type or catadioptric type, and reduces the circuit pattern of the reticle R by a magnification β (for example, β=1/2), and on a substrate (wafer) W coated with a photoresist. The image is projected onto the shot area. The projection optical system 130 includes an optical element 131 and an aperture stop 132. The optical element 131 moves on the optical axis of the projection optical system 130 by the driving unit 101. This makes it possible to improve the projection magnification and reduce distortion errors while suppressing an increase in various aberrations of the projection optical system 130. The aperture stop 132 is arranged on the pupil plane (Fourier transform plane for the reticle R) of the projection optical system 130. The shape is such that the opening is substantially circular, and the diameter is controlled by the driving unit 102. The drive units 101 and 102 are controlled by the projection optical system control unit 153.

The stage 140 is controlled by the driving unit 103 with respect to 6 degrees of freedom, and can position the substrate W. Here, the six degrees of freedom include translational degrees of freedom along each axis of the XYZ coordinate system and rotational degrees of freedom around each axis. The position of the stage 140 in the XY plane is measured by measuring the distance to the movable mirror 141 fixed to the stage 140 with the laser interferometer 142. The positional relationship between the stage 140 and the substrate W is measured by the alignment measurement system 104. The focus shift of the substrate W is measured by the focus surface detection unit including the projection optical system 105 and the detection optical system 106. The light projecting optical system 105 projects a plurality of light fluxes of non-exposure light that does not expose the photoresist on the substrate W, and the light fluxes are condensed and reflected on the substrate W, respectively. The light flux reflected on the substrate W enters the detection optical system 106. In the detection optical system 106, a plurality of light receiving elements for position detection are arranged corresponding to each reflected light beam. The light receiving surface of each light receiving element and the reflection point of each light beam on the substrate W are configured to be substantially conjugate by the imaging optical system. The focus shift is measured as a position shift of the incident light beam on the light receiving element in the detection optical system 106. The drive unit 103 is controlled by the stage control unit 154 based on each measurement result. The drive units 101 to 103 are drive means such as motors.

The suction unit 160 holds the substrate W on the stage 140 by vacuum suction under the control of the suction control unit 170. The control unit 150 centrally controls the illumination optical system control unit 151, the projection optical system control unit 153, the stage control unit 154, and the suction control unit 170.

FIGS. 2A and 2B are views of the two types of suction units 160 as viewed from above. FIG. 2A is suitable for adsorbing a warp or warp substrate. Here, the warped substrate is a substrate having a point on the substrate surface where the coordinate in the optical axis direction (Z direction) becomes the maximum when viewed from any direction in the XY plane. Further, the warped substrate is a substrate having a point where the coordinates are the minimum. FIG. 2B is suitable for adsorbing a warped substrate. Here, a saddle warped substrate has the maximum coordinates in the optical axis direction (Z direction) when viewed from a certain direction in the XY plane on the substrate surface, and the optical axis direction (Z direction) when viewed from another direction. It is a substrate that has so-called saddle points with the smallest coordinates. The suction unit 160 shown in FIG. 2A includes vacuum suction regions 11 to 13 divided by boundaries 21 to 23, discharge ports 31 to 33 for discharging the air sucked in the vacuum suction regions 11 to 13, and wafer transfer. It is provided with pin lift ports 41 to 43. The vacuum suction area is divided into concentric circles. The suction unit 160 shown in FIG. 2B includes vacuum suction regions 11 to 16 divided by a boundary 24, exhaust ports 31 to 36 for discharging air sucked in the vacuum suction regions 11 to 16, and wafer transfer pin elevating and lowering pins. With mouths 41-43. The vacuum suction area is radially divided. The wafer transfer pin elevating ports 41 to 43 are openings for moving up and down the wafer transfer pin 107 shown in FIG. 3 when transferring the substrate W to and from the substrate transfer hand (not shown). The substrate transfer hand places the substrate W on the wafer transfer pins 107 that have risen from the wafer transfer pin lift ports 41 to 43. After the substrate transfer hand is retracted, the wafer transfer pins 107 are lowered to place the substrate W on the suction unit 160.

FIG. 3 is a diagram showing the entire holding device including the suction portion 160 of FIG. The vacuum suction regions 11 to 13 are filled with a large number of small protrusions that support the substrate W during vacuum suction. The discharge ports 31 to 33 are connected to the solenoid valves SV1 to SV3 via piping. The solenoid valves SV1 to SV3 are connected to a vacuum pump 173 via a manifold 171 for branching a pipe. Pressure sensors P1 to P3 are provided in the pipes connected to the discharge ports 31 to 33, respectively. The pressure sensors P1 to P3 measure the pressure in the vacuum suction regions 11 to 13. The original pressure of the vacuum pump 173 is measured by the original pressure sensor 172. The adsorption control unit 170 controls the solenoid valves SV1 to SV3 based on the values of the pressure sensors P1 to P3, and causes the adsorption unit 160 to adsorb the substrate W in vacuum. The pressure sensor for measuring the pressure in each vacuum suction region may be arranged not in the exhaust outlet whole system but in the minimum necessary system.

FIG. 4 is a diagram showing a state where the warped substrate W is carried into the suction section 160. In the state of FIG. 4, the suction control unit 170 opens all of the solenoid valves SV1 to SV3 and vacuum sucks the vacuum suction regions 11 to 13 to suck the substrate W. At this time, the vacuum suction region, which is distant from the substrate W, cannot successfully suck the substrate W, and sucks ambient air as shown by an arrow in the drawing (idle suction). The pressure in the vacuum suction area where air suction is performed is higher than the pressure in the vacuum suction area where the substrate W is well sucked. Further, the amount of air suction increases as the distance between the substrate and the suction portion increases (=the measured pressure increases).

The substrate W has a warp shape, and the distance between the substrate W and the suction unit 160 increases from the center of the substrate toward the outer periphery. That is, the values indicated by the pressure sensors P1 to P3 increase in order. In this case, the adsorption control unit 170 controls to open the solenoid valves SV1 to SV3 in order. As a result, the suction unit 160 can suction and hold the substrate W with good flatness. FIG. 5 is a diagram showing a state in which the warped substrate W is carried into the suction unit 160. In this case, the adsorption order is opposite to that of the case of the substrate W having the downward warp shown in FIG. The release order (adsorption order) is determined by the control unit 150 based on the pressure values of the pressure sensors P1 to P3 sent from the adsorption control unit 170 to the control unit 150 so that the pressure values are in ascending order, and the storage unit. It is stored in 152. The stored suction order is read from the storage unit 152 by the control unit 150 when performing suction holding, and is output to the suction control unit 170. The suction control unit 170 executes vacuum suction based on the suction order sent from the control unit 150. It should be noted that the adsorption order may be set such that a plurality of electromagnetic valves whose pressure values are close to each other within a predetermined range are simultaneously opened (adsorption is started) instead of one by one.

FIG. 6 is a flowchart of the vacuum suction method by the holding device according to the present embodiment. In step S101, first, the control unit 150 controls a substrate transfer hand (not shown) to place the test substrate (first substrate) used for determining the suction order on the suction unit 160. The control unit 150 controls the suction control unit 170 to open all the solenoid valves SV1 to SV3 and vacuum suction the vacuum suction regions 11 to 13 to suck the test substrate. In step S102, the suction control unit 170 sends the pressure data measured by the pressure sensors P1 to P3 to the control unit 150. In step S103, the control unit 150 sets the adsorption order (opening order) based on the pressure data (for example, in ascending order). In step S104, the control unit 150 stores the set suction order in the storage unit 152. In step S105, the control unit 150 reads the adsorption order from the storage unit 152, controls the adsorption control unit 170, and adsorbs the substrate for manufacturing the device according to the read adsorption order.

The test substrate and the device manufacturing substrate are prepared so that they have the same shape including warpage. The test substrate may be prepared separately from the device manufacturing substrate, or the two substrates may be selected from the same lot. That is, the first substrate in the same lot may be used as the test substrate and the second substrate may be used as the device manufacturing substrate. In step S104, the suction order is stored by associating the shapes of the substrates. If the shapes of substrates in the same lot can be regarded as the same, the suction order is stored in association with the lot.

As described above, the holding device according to the present embodiment sets the optimum suction sequence for suppressing the suction based on the measurement of the suction pressure, and therefore, the additional configuration for measuring the flatness of the substrate and the suction amount by the suction are set. No additional configuration is needed to make up for the reduction. Further, it is also possible to support adsorption of substrates having various shapes. According to the present embodiment, it is possible to provide a holding device that is advantageous for holding the substrate with good flatness.

(Second embodiment)
This embodiment is a vacuum suction method when the information on the warp shape of the substrate W is known by actual measurement or the like. When the warp shape of the substrate W is known in advance, in step S103, the control unit 150 sets the suction order based on the distance between the substrate W and the suction unit 160 (for example, in order of decreasing distance). Therefore, step S101 and step S102 are unnecessary. According to this embodiment, the same effect as that of the first embodiment can be obtained.

(Third Embodiment)
The present embodiment is a vacuum suction method in which steps S101 and S102 of the first embodiment are omitted. In the present embodiment, in front of the step of placing the substrate W to the suction unit 160 (second holding portion), by members (first holding portion) for the same retention and suction holding by the suction unit 160, step S101 And the process equivalent to process S102 is performed. In step S103, the control unit 150 sets the adsorption order based on the pressure data. According to this embodiment, the same effect as that of the first embodiment can be obtained. As the member, there is a temperature control plate or the like.

(Embodiment of the article manufacturing method)
The method for manufacturing an article in the embodiment of the present invention is suitable for manufacturing an article such as a microdevice such as a semiconductor device or an element having a fine structure. The method for manufacturing an article according to the present embodiment includes a step of forming (exposing) a pattern on a substrate held by the holding device using the exposure device, and a substrate formed with the pattern in the step. Processing (developing). When the lithographic apparatus is an imprint apparatus, it includes, for example, a step of removing a residual film instead of the step of developing. Further, the manufacturing method includes other well-known steps (oxidation, film formation, vapor deposition, doping, planarization, etching, resist stripping, dicing, bonding, packaging, etc.). The article manufacturing method of the present embodiment is advantageous in at least one of the performance, quality, productivity, and production cost of the article as compared with the conventional method.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications can be made within the scope of the gist thereof.

160 adsorption unit 170 adsorption control unit W substrate

Claims (10)

A holding device for holding a substrate by vacuum suction.
A first suction portion having a plurality of suction regions;
A second suction part having the plurality of suction regions ;
Based on the pressure at which adsorbed the substrate by the first adsorption unit, determines the order in which to start the suction of the substrate by the plurality of suction areas in the second adsorption unit,
Start the adsorption of said plurality of adsorption regions in the follow the order the second adsorption unit, to have a, and a control unit for adsorbing the previous SL second adsorption unit the substrate,
A holding device characterized by the above. The pressure holding device according to claim 1, characterized in that the front Kimoto plate is the pressure in the plurality of absorptive region when adsorbed by said plurality of retaining regions in the first adsorption unit. The holding device according to claim 1, wherein the order is set in ascending order of the pressure. 2. The order is set so that the adsorption by the adsorption region in which the pressure is within a predetermined range among the plurality of adsorption regions in the second adsorption unit is started at the same timing. The holding device according to claim 1. The holding device according to claim 1, wherein the first adsorption unit includes a temperature control plate. A plurality of sensors that measure respective pressures of the plurality of suction regions in the first suction unit;
A plurality of valves provided in a plurality of pipes that connect the vacuum pump and each of the plurality of adsorption regions in the first adsorption unit,
The control unit controls the pressure of each of the plurality of adsorption regions in the first adsorption unit by the plurality of sensors in a state where the substrate is placed on the first adsorption unit and all of the plurality of valves are opened. The holding device according to claim 1, wherein the holding device measures. The holding device according to claim 6, wherein the control unit determines the order such that pressures measured by the plurality of sensors are in ascending order. The board A holding method for holding by vacuum suction,
A first adsorption step of adsorbing the substrate by a first adsorption part having a plurality of adsorption regions;
A determination step of, based on the pressure at the time of adsorbing the substrate in the first adsorption step, to determine the order in which to start the suction of the substrate by the second adsorption unit having a plurality of retaining regions,
Start the adsorption of said plurality of retaining regions in the second adsorption unit follow the order, having a second adsorption step of adsorbing pre Symbol substrate Ri by the second adsorption unit,
A holding method characterized by the above. A lithographic apparatus for forming a pattern on a substrate, comprising:
Lithographic apparatus comprising: a holding device according to any one of claims 1 to 7 for holding the substrate by vacuum suction. Forming a pattern on a substrate using the lithographic apparatus according to claim 9 ;
A step of processing the substrate having a pattern formed in the step ,
An article manufacturing method comprising: manufacturing an article from the processed substrate .

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