JP7448060B1 - electrostatic chuck - Google Patents

Abstract

The present invention provides an electrostatic chuck that can sufficiently suppress variations in in-plane temperature distribution of a substrate.
An electrostatic chuck 10 includes a dielectric substrate 100, an adsorption electrode 130 built into the dielectric substrate 100, an electrode terminal 50 provided on a surface 120 of the dielectric substrate 100, an adsorption electrode 130, and an electrode terminal 50 provided on a surface 120 of the dielectric substrate 100. A connection part 400 that electrically connects with the terminal 50 is provided. The connection portion 400 includes a flat pad portion 410 parallel to the surface 110 of the dielectric substrate 100 and a columnar via portion 420 perpendicular to the surface 110. Pad portions 410 and via portions 420 are arranged alternately along and connected to each other. The connection position of the via section 420 connected from one side to the pad section 410 and the connection position of the via section 420 connected from the other side are different from each other when viewed from above.
[Selection diagram] Figure 2

Description

The present invention relates to an electrostatic chuck.

For example, semiconductor manufacturing equipment such as a CVD equipment or an etching equipment is provided with an electrostatic chuck as a device for attracting and holding a substrate such as a silicon wafer to be processed. An electrostatic chuck includes a dielectric substrate provided with a suction electrode and a base plate supporting the dielectric substrate, and has a configuration in which these are joined to each other. When a voltage is applied to the attraction electrode, an electrostatic force is generated, and the substrate placed on the dielectric substrate is attracted and held.

A conductor layer substantially parallel to the mounting surface is embedded inside the dielectric substrate. The conductor layer is, for example, the above-mentioned adsorption electrode, but a heater, an RF electrode, or the like for heating the dielectric substrate may also be embedded as the conductor layer.

An electrode portion (for example, an electrode terminal) for supplying power to the conductor layer is provided at a position on the opposite side of the mounting surface of the dielectric substrate. The conductor layer and the electrode section are electrically connected by a connection section provided inside the dielectric substrate.

As described in Patent Document 1 listed below, a configuration in which flat pad portions and columnar via portions are alternately arranged is known as a configuration of the connection portion. A connection portion having such a configuration is suitable, for example, when a dielectric substrate is manufactured by laminating green sheets.

China Patent Application Publication No. 113707594

When the stacked green sheets are fired, each of the green sheets, via portions, etc. shrinks. Generally, the amount of shrinkage of the via portion is slightly larger than the amount of shrinkage of the surrounding green sheet.

In the electrostatic chuck described in Patent Document 1, the plurality of via portions arranged in a direction perpendicular to the mounting surface are arranged in a straight line. Therefore, when each via portion contracts during firing of the dielectric substrate, the amount of shrinkage of each via portion arranged in a straight line is integrated, resulting in a relatively large contraction as a whole. Become. The connection between the conductor layer and the electrode section shrinks significantly compared to the surrounding green sheet, resulting in problems such as disconnection in some of the connections, and power cannot be properly supplied to the conductor layer. There is a possibility that it will happen.

The present invention has been made in view of these problems, and its purpose is to provide an electrostatic chuck that can stably supply power to a conductor layer built into a dielectric substrate. .

In order to solve the above problems, an electrostatic chuck according to the present invention includes a dielectric substrate having a mounting surface on which an object to be attracted is placed, a conductor layer built in the dielectric substrate, and a The part that electrically connects the electrode section provided on the opposite side of the mounting surface, the conductor layer, and the electrode section, when viewed from the direction perpendicular to the mounting surface. and a connection portion provided within a range overlapping with the electrode portion. The connection part includes a flat pad part parallel to the mounting surface and a columnar via part perpendicular to the mounting surface. and via portions are arranged alternately and connected to each other, and the connection position of the via portion that is connected to the pad portion from one side, and the via portion that is connected to the pad portion from the other side. The connection positions are different from each other when viewed from a direction perpendicular to the mounting surface.

In an electrostatic chuck with such a configuration, the plurality of vias arranged in a direction perpendicular to the mounting surface are not arranged in a straight line as in the conventional case, but instead are arranged in a straight line when viewed from the direction perpendicular to the mounting surface. In this case, they are arranged so as to be connected to each other via the pad portion at different positions. Even if the respective via portions contract during firing, the respective amounts of shrinkage are not integrated, so the possibility that a disconnection or the like will occur in a part of the connection portion is extremely small. This makes it possible to stably supply power to the conductor layer built into the dielectric substrate.

Furthermore, in the electrostatic chuck according to the present invention, two via portions are connected to the pad portion from the same side along the direction perpendicular to the mounting surface, and when viewed from the direction perpendicular to the mounting surface. In this case, it is also preferable that these two via portions are arranged so as to sandwich the center of the pad portion therebetween. By arranging two via sections at the same step position so that they are lined up with the center of the pad section between them, there is more room to arrange the via sections at different step positions so that they are not lined up in a straight line. It becomes possible to secure a wide range of

Further, in the electrostatic chuck according to the present invention, the first direction is the direction in which the two via parts connected to the pad part from one side are lined up, and the direction in which the two via parts connected to the pad part from the other side are lined up is the first direction. When the second direction is the direction in which the via portions are lined up, it is also preferable that the first direction and the second direction are different from each other. By making the first direction and the second direction different from each other, it is possible to easily make different connection positions of the pair of via parts sandwiching the pad part.

Further, in the electrostatic chuck according to the present invention, it is also preferable that the angle formed between the first direction and the second direction is 90 degrees. It is possible to make the respective connection positions of the pair of via parts sandwiching the pad part the farthest from each other.

According to the present invention, it is possible to provide an electrostatic chuck that can stably supply power to a conductor layer built into a dielectric substrate.

FIG. 1 is a cross-sectional view schematically showing the configuration of an electrostatic chuck according to the present embodiment. FIG. 3 is a cross-sectional view showing a specific configuration of a connecting portion and its vicinity. FIG. 3 is a perspective view showing a specific configuration of a connecting portion. FIG. 3 is a diagram for explaining the arrangement of four via portions connected to one pad portion.

This embodiment will be described below with reference to the accompanying drawings. In order to facilitate understanding of the description, the same components in each drawing are denoted by the same reference numerals as much as possible, and redundant description will be omitted.

The electrostatic chuck 10 according to the present embodiment attracts and holds a substrate W to be processed using electrostatic force inside a semiconductor manufacturing apparatus (not shown) such as a CVD film forming apparatus, for example. The substrate W is, for example, a silicon wafer. The electrostatic chuck 10 may be used in equipment other than semiconductor manufacturing equipment.

FIG. 1 shows a schematic cross-sectional view of the structure of an electrostatic chuck 10 that holds a substrate W by suction. The electrostatic chuck 10 includes a dielectric substrate 100, a base plate 200, and a bonding layer 300.

The dielectric substrate 100 is a substantially disk-shaped member made of a ceramic sintered body. Dielectric substrate 100 includes, for example, high-purity aluminum oxide (Al ₂ O ₃ ), but may also include other materials. The purity, type, additives, etc. of the ceramics in the dielectric substrate 100 can be appropriately set in consideration of the plasma resistance required of the dielectric substrate 100 in semiconductor manufacturing equipment.

The upper surface 110 of the dielectric substrate 100 in FIG. 1 is a "placing surface" on which a substrate W, which is an object to be attracted, is placed. Further, a lower surface 120 of the dielectric substrate 100 in FIG. 1 (that is, a surface 120 on the opposite side to the surface 110) is a "surface to be bonded" to be bonded to the base plate 200 via a bonding layer 300, which will be described later. It becomes. The viewpoint when looking at the electrostatic chuck 10 from the surface 110 side along the direction perpendicular to the surface 110 will also be referred to as "top view" below.

An adsorption electrode 130 is embedded inside the dielectric substrate 100. The adsorption electrode 130 is a thin flat conductor layer made of a metal material such as tungsten, and is arranged parallel to the surface 110. As a material for the adsorption electrode 130, molybdenum, platinum, palladium, etc. may be used in addition to tungsten. Note that the adsorption electrode 130 only needs to be approximately entirely parallel to the surface 110, and may include a portion that is not parallel to the surface 110. When a voltage is applied to the attraction electrode 130 from the outside via a connection section 400, which will be described later, an electrostatic force is generated between the surface 110 and the substrate W, thereby attracting and holding the substrate W. Although two adsorption electrodes 130 may be provided as a so-called "bipolar" electrode as in this embodiment, only one adsorption electrode 130 may be provided as a so-called "unipolar" electrode.

Electrode terminals 50 are embedded in the surface 120 corresponding to the respective adsorption electrodes 130. The electrode terminal 50 and the adsorption electrode 130 are electrically connected by a connecting portion 400 provided inside the dielectric substrate 100. One end of the power supply path 13 is connected to each electrode terminal 50 . The power supply path 13 is a conductive metal member (for example, a bus bar), and is drawn out to the outside through a through hole (not shown) provided in the base plate 200. For example, a cylindrical insulating member may be provided between the inner surface of the through hole and the power supply path 13. The electrode terminal 50 is a portion of the dielectric substrate 100 that receives power from the outside at a position opposite to the surface 110. The electrode terminal 50 corresponds to the "electrode part" in this embodiment.

The connecting portion 400, the electrode terminal 50, and the power supply path 13 constitute an electric path for applying voltage to the adsorption electrode 130. In FIG. 1, the configuration of the connecting portion 400 and the like is illustrated in a simplified manner. The specific configuration of the connection section 400 will be explained later.

A space SP is formed between the dielectric substrate 100 and the substrate W. When a process such as film formation is performed in the semiconductor manufacturing apparatus, helium gas for temperature adjustment is supplied to the space SP from the outside through a gas hole (not shown) formed in the dielectric substrate 100. By interposing helium gas between the dielectric substrate 100 and the substrate W, the thermal resistance between the two is adjusted, thereby maintaining the temperature of the substrate W at an appropriate temperature. Note that the temperature adjustment gas supplied to the space SP may be a different type of gas than helium.

A seal ring 111 and dots 112 are provided on a surface 110 that is an attraction surface, and a space SP is formed around these.

The seal ring 111 is a wall that partitions the space SP at the outermost position. The upper end of each seal ring 111 forms part of the surface 110 and comes into contact with the substrate W. Note that a plurality of seal rings 111 may be provided so as to divide the space SP. With such a configuration, it is possible to individually adjust the pressure of helium gas in each space SP, and to make the surface temperature distribution of the substrate W close to uniform during processing.

In FIG. 1 and the like, the part marked with the symbol "116" is the bottom surface of the space SP. Hereinafter, this portion will also be referred to as the "bottom surface 116." The seal ring 111 is formed as a result of digging down a part of the surface 110 to the position of the bottom surface 116, together with the dots 112 described below. A groove may be formed in the bottom surface 116 to quickly diffuse helium gas within the space SP.

The dots 112 are circular protrusions that protrude from the bottom surface 116. A plurality of dots 112 are provided and are approximately evenly distributed on the attraction surface of the dielectric substrate 100. The upper end of each dot 112 forms part of the surface 110 and comes into contact with the substrate W. By providing a plurality of such dots 112, deflection of the substrate W is suppressed.

The base plate 200 is a substantially disk-shaped member that is joined to the surface 120 of the dielectric substrate 100 in order to support the dielectric substrate 100. The base plate 200 is made of metal such as aluminum, for example. The upper surface 210 of the base plate 200 in FIG. 1 is a "joined surface" that is joined to the dielectric substrate 100 via the joining layer 300. The surface of the base plate 200 including the surface 210 may be covered with an insulating film such as a sprayed alumina film.

Bonding layer 300 is a layer provided between dielectric substrate 100 and base plate 200, and bonds them together. The bonding layer 300 is a hardened adhesive made of an insulating material. As such an adhesive, for example, a silicone adhesive can be used.

A refrigerant flow path 250 for flowing refrigerant is formed inside the base plate 200. When a process such as film formation is performed in a semiconductor manufacturing apparatus, a coolant is supplied from the outside to the coolant channel 250, thereby cooling the base plate 200. Heat generated in the substrate W during processing is transferred to the coolant via the helium gas in the space SP, the dielectric substrate 100, and the base plate 200, and is discharged to the outside together with the coolant.

The specific configuration of the connection portion 400 and its vicinity in the dielectric substrate 100 will be described. FIG. 2 shows the configuration of this portion as a sectional view. FIG. 3 shows the configuration of the connecting portion 400 as a perspective view.

As shown in FIG. 2, a recess 121 is formed in the surface 120 of the dielectric substrate 100, and the electrode terminal 50 is held embedded in the recess 121. The electrode terminal 50 is a substantially cylindrical metal terminal. The central axis of the electrode terminal 50 is perpendicular to the plane 110 and the plane 120. In FIG. 2, the symbol "51" is a brazing material provided to cover the bottom surface (the upper surface in FIG. 2) of the recess 121, and is, for example, silver solder. The electrode terminal 50 is fixed to the recess 121 via the brazing material 51.

The above-mentioned “electrode portion” can be defined as a portion that is connected to the connection portion 400 from the surface 120 side and to which a voltage is applied from the outside. Therefore, the entirety of the electrode terminal 50 plus the brazing material 51 may be regarded as an "electrode section."

Range D in FIG. 2 represents a range that overlaps with the electrode terminal 50 when viewed from above. As shown in the figure, the connection part 400 that connects the electrode terminal 50 and the adsorption electrode 130 is provided so that the entire connection part 400 is within the range D. Instead of such a mode, a mode may be adopted in which a part of the connecting portion 400 (for example, a pad section 410 described below) extends outside the range D.

The connection section 400 has a plurality of pad sections 410 and a plurality of via sections 420, and has a configuration in which these are connected to each other. The plurality of pad sections 410 and the plurality of via sections 420 are arranged alternately along the direction perpendicular to the surface 110.

As shown in FIG. 3, the pad portion 410 is a flat layer formed to have a circular shape when viewed from above. Each pad portion 410 is parallel to plane 110. Note that the pad portion 410 only needs to be approximately entirely parallel to the surface 110, and may include a portion that is not parallel to the surface 110.

The dielectric substrate 100 of this embodiment is formed by laminating a plurality of so-called green sheets and firing them. The position where each pad portion 410 is provided corresponds to the boundary portion of the stacked green sheets. The pad portion 410 is formed, for example, by applying a conductive paste to a circular area on one side of the green sheet. The "conductive paste" is, for example, tungsten paste.

The via portion 420 is a substantially cylindrical portion that is formed to extend along a direction perpendicular to the surface 110. The via portion 420 is formed by forming a through hole (via) so as to penetrate the circular area of the green sheet, and filling the through hole with conductive paste. The conductive paste filled may be the same tungsten paste as the pad portion 410, but may be a different material.

The position of each green sheet in the direction perpendicular to the surface 110 will also be referred to as a "step position" below. As shown in FIGS. 2 and 3, the via portions 420 of this embodiment are arranged at each of six step positions, and two via portions 420 are arranged at each step position.

FIG. 4 schematically shows one pad section 410 included in the connection section 400 and a total of four via sections 420 connected thereto in a top view. In FIG. 4, the reference numeral "420A" indicates a via section 420 that is connected to the pad section 410 in the drawing from a step position on the near side of the paper. In FIG. 4, the reference numeral "420B" indicates a via section 420 that is connected to the pad section 410 in the drawing from a step position on the back side of the drawing.

As shown in FIG. 4 and the like, in the connection section 400 of this embodiment, the connection position of the via section 420A is connected to the pad section 410 from one side, and the connection position of the via section 420A is connected to the pad section 410 from the other side. The respective via portions 420 are arranged so that the connection positions of the via portions 420B are different from each other when viewed from above. In other words, there is no pair of via portions 420 that are aligned in a straight line with the pad portion 410 in between.

In addition, in the above, the connection positions "are different from each other" refer to the connection position of the via part 420A connected to the pad part 410 from one side, and the connection position of the via part 420B connected to the pad part 410 from the other side. This means that the connection positions do not overlap with each other at all when viewed from above. Instead of such a mode, a portion of each connection position may be overlapped with each other.

The advantages of having such a configuration will be explained. When manufacturing the dielectric substrate 100 by laminating and firing green sheets as in this embodiment, each of the green sheets, via portions 420, etc. shrinks during firing. In general, the amount of contraction of the via portion 420 is often slightly larger than the amount of contraction of the green sheet surrounding it.

If the via sections 420 at different step positions are arranged in a straight line, when each via section 420 contracts during firing, the respective via sections 420 arranged in a straight line will shrink. As a result of the cumulative amount, a relatively large contraction will occur overall. Since the connection part 400 that connects the adsorption electrode 130 and the electrode terminal 50 shrinks significantly compared to the surrounding green sheet, problems such as disconnection occur in a part of the connection part 400, and the power supply to the adsorption electrode 130 is interrupted. There is a possibility that it will not be done properly.

Therefore, in the electrostatic chuck 10 according to the present embodiment, as described above, the arrangement of the via portions 420 in the connecting portion 400 is devised so that the via portions 420 that sandwich the pad portion 410 therebetween are not lined up in a straight line.

In such a configuration, even if each via portion 420 contracts during firing, the amount of each contraction will not be integrated, so there is no possibility that a break in a part of the connecting portion 400 will occur. It has become extremely small. This makes it possible to stably supply power to the adsorption electrode 130 built into the dielectric substrate 100.

As shown in FIGS. 3 and 4, two via portions 420 are connected to one pad portion 410 from the same side along the direction perpendicular to the surface 110. Among these, if the center of each of the pair of via portions 420A on the near side of the paper in FIG. 4 is C1, the center C0 of the pad portion 410 in a top view exists on a straight line connecting C1. Similarly, in FIG. 4, if the center of each of the pair of via portions 420B on the back side of the page is C2, the center C0 of the pad portion 410 in a top view is on a straight line connecting C2.

In this manner, in this embodiment, the two via sections 420 at the same step position are arranged so as to sandwich the center C0 of the pad section 410 between them when viewed from above. By arranging the via portions 420 at each step position in this manner, a wide margin is secured for arranging the via portions 420 at different step positions so that they are not lined up in a straight line.

In FIG. 4, the direction from one C1 to the other C1, that is, the direction in which two via sections 420A connected from one side to the pad section 410 in FIG. Also referred to as "AR1". Further, the direction from one C2 to the other C2, that is, the direction in which the two via parts 420B connected from the other side to the pad part 410 in FIG. 4 are lined up is hereinafter referred to as "second direction AR2". Also called.

In this embodiment, by making the first direction AR1 and the second direction AR2 that are defined in this way different from each other, the respective connection positions of the pair of via parts 420A and 420B sandwiching the pad part 410 can be easily made different. It is now possible.

The angle θ between the first direction AR1 and the second direction AR2 is 90 degrees in this embodiment. With such a configuration, the connection positions of the pair of via parts 420A and 420B sandwiching the pad part 410 can be made farthest from each other.

Various changes can be made to the configuration of the connection section 400 and the like described above. In this embodiment, the electrode terminal 50 and brazing material 51 provided on the surface 120 of the dielectric substrate 100 correspond to an "electrode section" that receives power from the outside. Instead of this configuration, for example, a plate-shaped metal may be placed at the position of the brazing material 51, and a rod-shaped pin inserted from the outside may be brought into contact with the metal. In this case, the above-mentioned plate-shaped metal corresponds to the "electrode part".

In this embodiment, the attraction electrode 130 provided inside the dielectric substrate 100 corresponds to a "conductor layer", and the connecting portion 400 is provided so as to be connected to the attraction electrode 130. Instead of this embodiment, an RF electrode or an electric heater may be provided as a "conductor layer" inside the dielectric substrate 100, and a connecting portion 400 may be provided so as to be connected to these.

The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Design changes made by those skilled in the art as appropriate to these specific examples are also included within the scope of the present disclosure as long as they have the characteristics of the present disclosure. The elements included in each of the specific examples described above, their arrangement, conditions, shapes, etc. are not limited to those illustrated, and can be changed as appropriate. The elements included in each of the specific examples described above can be appropriately combined as long as no technical contradiction occurs.

W: Substrate 10: Electrostatic chuck 100: Dielectric substrate 110, 120: Surface 130: Adsorption electrode 400: Connection portion 410: Pad portion 420: Via portion

Claims (4)

a dielectric substrate having a placement surface on which an object to be attracted is placed;
a conductor layer built into the dielectric substrate;
an electrode terminal provided at a position opposite to the mounting surface of the dielectric substrate and having a circular shape when viewed from a direction perpendicular to the mounting surface ;
A portion that electrically connects between the conductor layer and the electrode terminal , and is provided within a range where the entire portion overlaps with the electrode terminal when viewed from a direction perpendicular to the placement surface. comprising a connection part;
The connection part is
a flat pad portion parallel to the mounting surface;
a columnar via portion perpendicular to the mounting surface;
The pad portions and the via portions are arranged alternately along a direction perpendicular to the mounting surface and are connected to each other,
A connection position of the via part connected to the pad part from one side and a connection position of the via part connected to the pad part from the other side are in a direction perpendicular to the mounting surface. An electrostatic chuck characterized by being different from each other when viewed from above. The pad part includes
The two via portions are connected from the same side along a direction perpendicular to the mounting surface,
When viewed from a direction perpendicular to the mounting surface, the two via portions are arranged side by side with the center of the pad portion in between. Electrostatic chuck described in . A first direction is a direction in which the two via portions connected to the pad portion from one side are lined up;
When the second direction is the direction in which the two via portions connected to the pad portion from the other side are lined up,
The electrostatic chuck according to claim 2, wherein the first direction and the second direction are different from each other. The electrostatic chuck according to claim 3, wherein an angle between the first direction and the second direction is 90 degrees.

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