JP6824003B2 - Tray with electrostatic chuck - Google Patents

Description

The present invention relates to a tray with an electrostatic chuck for adsorbing and holding a foil-like substrate made of metal containing silicon in a chamber in a vacuum atmosphere.

This type of tray with an electrostatic chuck is known, for example, in Patent Document 1. This includes a tray body in which electrodes fed from a power source (power supply for ESC) are embedded, so that the tray body is placed on a stage in a vacuum chamber in which a predetermined plasma treatment is performed. It has become. The stage is provided with a power supply terminal that can move forward and backward in the vertical direction, and when the power supply terminal is moved to a protruding position, it comes into contact with an electrode to supply power. Further, a frame-shaped cover member is placed on the tray body so that a base material receiving portion for receiving a base material such as a silicon wafer is defined. In this case, the tray body and the cover body are fixed to the stage by pressing the cover member toward the stage with the clamp. Then, when the electrode is a so-called unipolar type, when a base material such as a silicon wafer is housed in the base material receiving portion and then power is supplied from the power source to the electrode in a state where plasma is generated in a chamber in a vacuum atmosphere, at that time. The base material is electrostatically adsorbed on the upper surface (adsorption surface) of the tray body by the electrostatic force generated in.

By the way, among the objects to be treated by plasma treatment, there is a metal foil-like base material containing silicon (for example, one having a thickness of 100 μm or less), and among them, for example, as a pretreatment. Some of them are deformed due to the stress of the film (for example, the base material is warped or locally distorted) due to the film forming process of. Even if the foil-like base material deformed in this way is electrostatically adsorbed by the tray with the electrostatic chuck of the above-mentioned conventional example, the base material is statically in contact with the upper surface of the tray body over the entire surface. It may not be electrically adsorbed (in other words, a region that is not adsorbed by the tray body may be locally generated in the surface of the base material). In this case, during the plasma treatment, for example, the base material is partially peeled off or lifted up, which causes a problem that the desired plasma treatment cannot be performed over the entire surface of the base material. When the deformed foil-like base material is electrostatically adsorbed on the tray, it is conceivable that the base material is pressed against the tray over the entire surface while rolling the roller along the surface of the base material. This can damage the substrate when the rollers roll, and can no longer be applied, especially if the substrate has been pretreated.

Japanese Patent No. 5082009

In view of the above points, the present invention provides a tray with an electrostatic chuck that ensures electrostatic adsorption over the entire surface even when the foil-like base material is deformed. This is an issue.

In order to solve the above problems, the present invention includes a tray body provided with electrodes supplied from a power source, and a silicon or metal foil-like base material on the suction surface of the tray body in a chamber in a vacuum atmosphere. In a tray with an electrostatic chuck that electrostatically attracts, a frame-shaped pressing plate that can press a predetermined range of the peripheral edge of the substrate toward the tray body with the substrate installed on the adsorption surface of the tray body. Further, the tray body receives a base material having a larger contour than the base material and a predetermined peripheral wall height higher than the base material thickness on either the suction surface of the tray body or the inner peripheral edge portion of the holding plate on the base material side. parts is recessed, the ratio of the thickness of the substrate relative to peripheral wall height of the base receiving portion is set to a range of 1 / 15-1 / 5, characterized in Rukoto.

According to the present invention, when the tray body is installed in a horizontal position, the base material is first placed on the upper surface of the tray body as a suction surface. When the base material is placed, the inner peripheral edge portion faces the peripheral edge portion of the base material, and the tray body is positioned so that a gap exists between the peripheral wall and the outer peripheral portion of the base material over the entire circumference. Temporarily install the holding plate from above. At this time, the base material is housed in the base material receiving portion, but since the height of the peripheral wall of the base material receiving portion is set higher than the base material thickness, for example, the outer edge of the base material is entirely or partially. When the tray is deformed so as to warp upward, a predetermined range of the peripheral edge of the base material is pressed toward the tray main body at the inner peripheral edge of the presser plate by the weight of the presser plate. As a result, the distance from the adsorption surface can be made smaller than a predetermined value (that is, the distance at which the substrate can be adsorbed by the electrostatic force generated by the power supply to the electrodes) at any part of the base material surface. it can.

As a result, in the case where the electrodes are of the so-called unipolar type, when power is supplied from the power supply to the electrodes while plasma is generated in the chamber, the electrostatic force generated at that time causes the upper surface (adsorption surface) of the tray body. The base material is reliably electrostatically adsorbed over the entire surface. According to the experiments conducted by the present inventors, it was confirmed that if a range of 80% or more of the peripheral edge of the base material is pressed, electrostatic adsorption is carried out over the entire surface. In addition, when the outer edge of the base material is deformed so as to warp downward, when the base material is placed on the suction surface, it sinks under its own weight, so that any of the inside of the base material surface can be used. At this point, the distance from the suction surface is smaller than the predetermined value, and at this time, the contour of the base material accommodating portion is larger than that of the base material, so that the base material is electrostatically charged on the suction surface in a wrinkled state. There is no problem of being adsorbed.

In the present invention, it is preferable that the holding plate is formed so that the inner peripheral edge portion thereof faces the peripheral edge portion of the base material over the entire circumference thereof. As a result, by simply temporarily installing the holding plate, the inner peripheral edge of the holding plate can press a predetermined range of the peripheral edge of the base material toward the tray body regardless of the deformed state of the base material. During plasma processing, the holding plate serves as a cover for preventing plasma processing on the tray, which is advantageous. In this case, if the holding plate is electrostatically attracted to the tray body together with the base material by supplying power from the power source to the electrodes, the holding plate is fixed, which is necessary to hold the peripheral portion of the base material in a pressed state. It is advantageous because the parts for use can be omitted.

The figure which shows typically the structure of the etching apparatus which includes the tray with the electrostatic chuck of this invention. FIG. 5 is an enlarged cross-sectional view showing a main part of FIG. The plan view which shows the main part of FIG. 1 enlarged. The figure which shows the experimental result for confirming the effect of this invention. The cross-sectional view which shows the modification of the tray with an electrostatic chuck. The plan view which shows the other modification of the tray with an electrostatic chuck.

Hereinafter, referring to the drawings, the object to be adsorbed is a metal foil-like base material Fs containing silicon, which has a rectangular outline and a thickness of 100 μm or less, and is subjected to a predetermined plasma treatment in the chamber. Then, an embodiment of a tray with an electrostatic chuck for electrostatically adsorbing the base material Fs in a chamber in a vacuum atmosphere will be described. In the following, it is assumed that the tray body is installed in a horizontal position in the chamber, and the term indicating the direction is based on this.

With reference to FIG. 1, the EM is an etching apparatus that performs an etching process as a plasma process on the foil-shaped substrate Fs (so-called reactive ion). The etching apparatus EM includes a load lock chamber 1 and a process chamber 2 which are connected in the horizontal direction via a gate valve Gv. The load lock chamber 1 is provided with a vacuum pump and a vent valve (not shown) so that the atmosphere in the chamber can be appropriately switched between atmospheric pressure and a predetermined pressure lower than atmospheric pressure. Further, the load lock chamber 1 is provided with a first stage 11 that enables the installation of the tray body 51 described later, so that the base material Fs can be set after the tray body 51 is installed on the first stage 11. ing.

In the process chamber 2, an upper opening 21 and a lower opening 22 are opened, the upper opening 21 is closed by a top plate 23 formed of a dielectric material such as quartz, and the lower opening 22 is also used as a vacuum seal in the process chamber 2. It is closed by a second stage 24 arranged via an insulator I, and can be evacuated to a predetermined pressure by a vacuum pump (not shown). A gas pipe 3 communicating with a gas source is connected to the side wall of the process chamber 2 via a flow rate control means (mass flow controller) (not shown), and a predetermined etching gas is introduced into the process chamber 2 in a vacuum atmosphere at a predetermined flow rate. I am trying to do it. Further, on the outside (upper side) of the top plate 23, a loop-shaped antenna coil 4 having a plurality of stages (two stages in the present embodiment) is provided, and the output from the high frequency power supply E1 is connected to the antenna coil 4 to generate plasma. It is possible to input high frequency power for generation.

With reference to FIG. 2, a through hole 24a penetrating in the vertical direction is formed in the second stage 24, and an immersion position where the tip is immersed in the through hole 24a and a through hole at the tip are formed in the through hole 24a. A connection terminal 25 that can move up and down is provided between the protruding position and the protruding position protruding upward from 24a. The connection terminal 25 is connected to the electrostatic chuck power supply Es, and the connection terminal 25 can be brought into contact with the electrode 53 described later to supply power to the electrode 53. The vertical movement of the connection terminal 25 can be performed by using a known drive mechanism. Further, the output from the high frequency power supply E2 is connected to the second stage 24, and a bias potential can be applied to the foil-shaped base material Fs during etching. Then, it is installed on the second stage 24 in the process chamber 2, and in order to electrostatically attract and hold the foil-shaped base material Fs, the tray with an electrostatic chuck of the present embodiment (hereinafter referred to as "tray 5"). ) Is used. Hereinafter, a so-called unipolar electrode 53 will be specifically described as an example.

With reference to FIGS. 2 and 3, the tray 5 includes a plate-shaped tray main body 51 and a pressing plate 52 having a rectangular contour corresponding to the foil-shaped base material Fs. The tray body 51 is made of a dielectric material such as alumina or quartz, and a single electrode 53 made of a conductor such as copper or aluminum is embedded therein. In this case, although not particularly illustrated and described, the electrode 53 is provided with a connection electrode portion that leads to a predetermined position on the lower surface of the tray body 51, and the connection terminal 25 at the protruding position is fitted to the connection electrode portion. I have to. Further, on the upper surface of the tray body 51, a base material receiving portion 54 that receives the base material Fs with a contour larger than that of the base material Fs is recessed. The height h of the peripheral wall 54a of the base material receiving portion 54 is set to be higher than the base material Fs by a predetermined value according to the power supply voltage from the electrostatic chuck power supply Es and the thickness t of the base material Fs. Has been done. Then, the base material Fs is placed on the horizontal bottom surface 54b of the base material receiving portion 54 by positioning so that a predetermined gap W (for example, 2 mm) exists between the peripheral wall 54a and the entire circumference thereof. .. In this case, the bottom surface 54b of the base material receiving portion 54 constitutes the adsorption surface of the base material Fs. The gap W is preferably set in the range of 2 mm to 3 mm in consideration of deformation of the base material Fs, positional deviation, and the like. Further, the tray body 51 may be appropriately fixed to the second stage 24 by a known fixing means such as a magnet or a clamp.

The presser plate 52 is made of, for example, a frame-shaped plate material made of aluminum or titanium. In this case, a central opening 52b is provided in the pressing plate 52 so that the inner peripheral edge portion 52a of the pressing plate 52 can face the peripheral edge portion Fs1 of the base material Fs over the entire circumference thereof. In the present embodiment, the case of the peripheral portion Fs1 of the base material Fs means the range within 3 mm from the end portion of the base material Fs. Then, in the pressing plate 52, after the base material Fs is placed on the horizontal bottom surface (adsorption surface) 54b of the base material receiving portion 54, the inner peripheral edge portion 52a of the pressing plate 52 is placed on the peripheral edge portion Fs1 of the base material Fs. It is positioned so as to face each other over the entire circumference thereof, and is temporarily installed from above the tray main body 51. Next, the procedure for adsorbing and holding the base material Fs in the process chamber 2 will be described.

First, in the load lock chamber 1 under atmospheric pressure, the tray body 51 is installed on the first stage 11, and then a predetermined gap (for example, 2 mm) exists between the tray body 51 and the peripheral wall 54a over the entire circumference thereof. The base material Fs is placed on the horizontal bottom surface 54b of the base material receiving portion 54 so as to be positioned. When the base material Fs is placed on the tray body 51, the load lock chamber 1 is evacuated, and when a predetermined pressure is reached, the gate valve Gv is opened to move the tray body 51 on which the base material Fs is placed into the process chamber 2. The tray body 51 is installed on the second stage 24. Here, a transfer robot is used to transfer the tray body 51 and the base material Fs in the load lock chamber 1 and to transfer the tray body 51 between the load lock chamber 1 and the process chamber 2. Such transfer. Since the robot itself is known, detailed description thereof will be omitted. In the present embodiment, since the base material Fs is installed in the base material receiving portion 54 recessed in the upper surface of the tray body 51, the base material Fs is less likely to fall from the tray body 51 during transportation by the transfer robot. It is advantageous.

When the tray main body 51 is installed on the second stage 24, the inner peripheral edge portion 52a of the pressing plate 52 is positioned so as to face the peripheral edge portion Fs1 of the base material Fs over the entire circumference of the tray main body 51. Temporarily installed from above. As a result, for example, when the outer end of the base material Fs is deformed so as to warp upward in whole or in part, and there is a portion protruding upward from the peripheral wall 54a of the base material receiving portion 54. Due to the weight of the pressing plate 52, a predetermined range of the peripheral edge Fs1 of the base material Fs is pressed toward the tray body 51 by the inner peripheral edge portion 52a of the pressing plate 52, and the suction surface is pressed at any place in the base material surface. The distance from 54b becomes smaller than a predetermined value (that is, the distance at which the base material Fs can be adsorbed by the electrostatic force generated by the power supply to the electrode 53). When the outer end of the base material Fs is deformed so as to warp downward, when the base material Fs is placed on the suction surface 54b, it sinks under its own weight, so that the base material surface The distance from the suction surface 54b is smaller than the predetermined value at any of the above points.

Next, a predetermined etching gas is introduced into the process chamber 2, and high-frequency power for plasma generation is applied to the antenna coil 4 by the high-frequency power supply E2 to generate plasma. Then, when the electrode 53 is supplied with a voltage in the range of 4 kV to 5 kV from the electrostatic chuck power supply Es in the state where plasma is generated, the electrostatic force generated at that time is applied to the upper surface (adsorption surface 54b) of the tray body 51. The base material Fs and the pressing plate 2 are reliably electrostatically adsorbed over the entire surface thereof. In this state, the base material Fs is etched. After the etching process is completed, when the high-frequency power is applied to the antenna coil 4 and the power supply to the electrode 53 is stopped, the electrostatic force disappears, so that the holding plate 52 is detached from the tray body 51 and the gate valve Gv is opened. The tray body 51 on which the etched base material Fs is placed is conveyed to the load lock chamber 1, and the base material Fs is recovered.

According to the above embodiment, the base material Fs can be reliably electrostatically adsorbed on the upper surface (adsorption surface 54b) of the tray body 51 over the entire surface by the electrostatic force generated when the electrode 53 is fed. Moreover, there are no problems such as wrinkles. Further, since the presser plate 52 adopts a structure in which the inner peripheral edge portion 52a is formed so as to face each other over the entire length of the peripheral edge portion Fs1 of the base material Fs, the base material Fs can be simply installed by temporarily installing the presser plate 52. Regardless of the deformed state of the pressing plate 52, the inner peripheral edge portion 52a of the pressing plate 52 can press a predetermined range of the peripheral edge portion Fs1 of the base material Fs toward the tray body 51, and the pressing plate 52 is pressed against the tray during plasma processing. It serves as a cover for preventing plasma processing on the main body 51, which is advantageous. Further, since the tray body 51 adopts a configuration in which the tray body 51 is electrostatically attracted to the tray body 51 together with the base material Fs by supplying power from the power source Es to the electrode 53, the peripheral portion Fs1 of the base material Fs is held in a pressed state. It is advantageous because the necessary parts for fixing the holding plate can be omitted.

Next, in order to confirm the effect of the present invention, the following experiment was carried out using the above etching apparatus EM. In this experiment, the base material Fs was made of 100 × 100 mm aluminum rectangle, the tray body 51 was made of alumina having a thickness of Φ330 mm and a thickness of 2 mm, and the holding plate 52 was made of Φ330 mm and a thickness of 1 mm. It was made of aluminum. In this case, a rectangular opening 52b is formed in the central portion of the pressing plate 52 so that a range of 3 mm from the outer end of the base material Fs contacts the inner peripheral edge portion 52a of the pressing plate 52. Further, it was decided to set the voltage when supplying power to the electrode 53 to 4 kV. On the other hand, as the etching conditions, argon gas was used as the etching gas, the etching gas was introduced so that the pressure in the process chamber 2 became 1 Pa, and the input power to the antenna coil 4 was set to 2.5 kW. .. Then, while appropriately changing the height h of the peripheral wall portion 54a and the thickness t of the base material Fs, the electrostatic adsorption state on the upper surface (adsorption surface 54b) of the tray body 51 was visually confirmed in the atmosphere.

FIG. 4 is a table showing an electrostatic adsorption state when the height h of the peripheral wall portion 54a and the thickness t of the base material Fs are changed. In the figure, ◯ indicates the base material Fs and the presser foot during the etching process. The plate 52 did not peel off from the chuck body 51, Δ indicates that the base material Fs and the holding plate 52 sometimes peeled off from the chuck body 51 when repeatedly etched, and × indicates the base material during the etching process. The Fs and the pressing plate 52 are peeled off from the chuck main body 51. According to this, if the height h of the peripheral wall portion 54a is smaller than 0.1 mm, the base material Fs and the pressing plate 52 are peeled off from the chuck body 51 regardless of the thickness t of the base material Fs, while the peripheral wall. It was confirmed that when the height h of the portion 54a is larger than 0.4 mm, the base material Fs and the pressing plate 52 are easily peeled off from the chuck main body 51 as the thickness t of the base material Fs becomes thinner. Therefore, if the ratio of the thickness t of the base material to the height h of the peripheral wall portion 54a is in the range of 1/15 to 1/5, the upper surface of the tray body is subjected to electrostatic force regardless of the deformation state of the base material. (Adsorption surface) can be reliably electrostatically adsorbed over the entire surface. Further, it was confirmed that electrostatic adsorption can be performed if the voltage for supplying power to the electrodes is in the range of 4 kV to 5 kV.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above. In the above embodiment, the case where the base material receiving portion 54 is recessed on the upper surface of the tray main body 51 has been described as an example, but the present invention is not limited to this, and as shown in FIG. 5, it is formed on the lower surface of the pressing plate 52. The base material receiving portion 54 may be recessed. In this case, the annular bottom surface portion extending toward the center of the pressing plate 52 serves to press a predetermined range of the peripheral edge portion of the base material Fs toward the tray main body 51. Further, in the above-described embodiment, the pressing plate 52 is formed of a frame-shaped plate material, and the peripheral portion Fs1 of the base material Fs is configured to be pressed over the entire circumference thereof. As described above, arc-shaped projecting pieces extending toward the center of the pressing plate 52 are provided at predetermined intervals in the circumferential direction, and the outer ends of the base materials Fs are deformed so as to warp upward as a whole. If 80% or more of the peripheral portion of the base material Fs is pressed during this time, the electrostatic force generated when power is supplied to the electrode 53 is based on the upper surface (adsorption surface) of the tray body 51. It was confirmed that the material Fs can be reliably electrostatically adsorbed over the entire surface thereof.

Further, in the above embodiment, the tray body 51 and the pressing plate 52 have been described as a rectangular shape corresponding to the contour of the base material Fs, but the present invention is not limited to this, and for example, a circular contour is used. There may be. Further, in the above embodiment, the case where the tray main body 51 is installed on the horizontally installed second stage 24 has been described as an example, but the present invention is not limited to this, and in the above embodiment, the electrode 53 Although the so-called unipolar type has been described as an example, the present invention can also be applied to the so-called bipolar type.

Es ... power supply, Fs ... base material, Fs1 ... base material Fs peripheral edge, t ... base material thickness (base material Fs thickness), 2 ... chamber (process chamber), 5 ... tray with electrostatic chuck, 51 ... Tray body, 52 ... Presser plate, 52a ... Inner peripheral edge of presser plate 52, 53 ... Electrode, 54 ... Base material receiving part, 54b ... Adsorption surface (upper surface of tray body 51), h ... Peripheral wall height (base material) The height of the peripheral wall portion 54a of the receiving portion 54).

Claims (3)

In a tray with an electrostatic chuck that has a tray body provided with electrodes supplied from a power source and electrostatically sucks a foil-like substrate made of silicon or metal on the suction surface of the tray body in a chamber in a vacuum atmosphere.
With the base material installed on the suction surface of the tray body, a frame-shaped presser plate that can press a predetermined range of the peripheral edge of the base material toward the tray body is further provided, and the suction surface of the tray body and the presser plate A base material receiving portion having a contour larger than that of the base material and a predetermined peripheral wall height higher than the thickness of the base material is recessed on either one of the inner peripheral edges on the base material side .
The thickness ratio of the base relative to the peripheral wall height of the base receiving portion, 1/15 to 1/5 is set in a range of the electrostatic chuck with trays, wherein Rukoto. The tray with an electrostatic chuck according to claim 1, wherein the holding plate is formed so that the inner peripheral edge thereof faces the peripheral edge portion of the base material over the entire circumference thereof. The tray with an electrostatic chuck according to claim 1 or 2, wherein the holding plate is electrostatically attracted to the tray body together with the base material by supplying power from the power source to the electrodes.

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