JP2010148177A - Electrostatic chuck and substrate bonding device equipped therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent uneven stress from being distributed in a substrate by external force to maintain the flatness of the substrate and enhance the quality of the bonded substrate. <P>SOLUTION: An electrostatic chuck device includes: a bottom portion 80; and an electrostatic force producing portion comprised of an insulating layer 91, an electrode layer 92, and a dielectric layer 93, provided on the upper face of the bottom portion. The bottom portion includes an elastic layer formed of an elastic material having elastic restitutive force. A substrate bonding device includes this electrostatic chuck device. The bottom portion includes a two-layer structure and is comprised of: the elastic layer formed of the elastic material having elastic restitutive force; and a non-elastic layer formed of a non-elastic material, positioned on one side of the elastic layer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to an electrostatic chuck (ESC) apparatus. More specifically, in an electrostatic chuck apparatus used for substrate adsorption in a substrate bonding process when manufacturing a liquid crystal panel, an electrostatic layer made of an elastic material is provided at the base of the electrostatic chuck. The present invention relates to a chuck and a substrate bonding apparatus including the chuck.

The electrostatic chuck is a part where a substrate (glass or wafer) is placed inside a vacuum chamber of a semiconductor and LCD manufacturing equipment, and is a component that fixes the substrate only by electrostatic force.

The principle of the electrostatic chuck is that, as is well known, the substrate is made using Coulomb force and Johnsen-Rahbeck force generated in a dielectric layer located between the electrode and the substrate. It is adsorbing. Such electrostatic chucks are roughly classified into polyimide type electrostatic chucks and ceramic type electrostatic chucks.

Regarding the electrostatic chuck structure, Patent Document 1 discloses an electrostatic chuck including an insulating layer, an electrode layer, and a dielectric layer for adsorbing a wafer using electrostatic energy. Patent Document 2 discloses an electrostatic chuck that forms a capacitor plate having a plurality of structures and attracts a wafer with electrostatic energy.

The electrostatic chuck is largely composed of an electrostatic chuck base and an electrostatic force generator on the upper surface thereof, and the electrostatic force generator is composed of an insulating layer, an electrode layer, and a dielectric layer. An adsorbate such as a substrate is placed on the dielectric layer of the electrostatic force generator. When a voltage is applied to the electrode layer, a positive (+) charge is generated on one side and a negative (-) charge is generated on the other side in the dielectric layer positioned between the substrate and the electrode layer. As such, electrical energy acts between them to adsorb the substrate.

Such an electrostatic chuck is used in a substrate manufacturing process. For example, in manufacturing an LCD, after manufacturing a TFT substrate and a CF (Color Filter) substrate, the two substrates are bonded together, and a space between them is formed. A step of injecting a liquid crystal material is required.

Such a substrate bonding step is performed by a substrate bonding apparatus including a chamber chamber composed of an upper chamber and a lower chamber that can be formed in a vacuum state. In order to attract the substrate to the upper surface plate of the upper chamber and the lower surface plate of the lower chamber, an electrostatic chuck is mainly used as a substrate attracting means.

In the substrate bonding process, aligning the upper and lower substrates with a certain gap while maintaining parallelism and flatness is an important step in determining quality in the entire process.

In the substrate bonding apparatus, a method of aligning the position of the mark center point of the substrate by the Z-axis fine alignment means is used in order to maintain the gap and parallelism between the substrates. Such fine alignment means can contribute to the improvement of parallelism.

However, the flatness of the entire substrate surface due to the deformation of the substrate cannot be adjusted. The reason for obstructing the flatness of the substrate is that non-uniform stress is applied to the substrate and deformation occurs. Further, such a phenomenon becomes deeper as the processed substrate has a larger area.

Factors that cause non-uniform stress to be applied to the substrate include fixed factors due to chamber sinking due to chamber load, and variable factors that cause the chamber chamber to be in a vacuum state during the substrate bonding process and deformed due to pressure differences. Is mentioned.

When there is no means to prevent such deformation when deformation occurs in the chamber, such deformation is transmitted to the substrate, leading to deformation of the substrate, which ultimately reduces the quality of the bonded substrate. Connected.

Among such deformations, the deformation due to the chamber load is a static deformation and can be adjusted by the initial setting. However, the deformation due to the pressure difference is dynamic during the machining process, and it becomes a problem to eliminate the influence of this. In particular, such an effect is more serious in the upper chamber than in the lower chamber fixed to the base frame.

Below, the deformation | transformation by a pressure difference among the problems by each influence is demonstrated centering on an upper chamber part.

The substrate bonding step is performed in a chamber chamber whose inside is in a vacuum state. At this time, a compressive force is generated inside and outside the chamber due to a difference in atmospheric pressure inside and outside the chamber. Due to such a compressive force, the chamber is generally deformed in a shape in which the central portion sinks. On the other hand, such deformation is propagated to the inside of the chamber, is also propagated to the electrostatic chuck mechanically fastened to the chamber, and finally is transmitted to the substrate adsorbed to the electrostatic chuck. appear.

FIG. 1 schematically shows the deformation of the adsorbed substrate due to the deformation of the processing chamber. As shown in FIG. 1, the chamber 10 receives a compression force from the outside to the inside due to a pressure difference between the inside and the outside due to vacuum evacuation, and the chamber shows a deformation in which the central portion is bent by such a compression force. Such a deformation is applied to the substrate adsorbed to the chamber by the substrate support portion 20, and the substrate P is entirely bent at the center.

The deformation of the substrate will be described in more detail with reference to FIG.

The center point X of the alignment mark of the substrate P before deformation and the center point X ′ of the alignment mark of the substrate P ′ after deformation, as shown in the figure, show a difference as the substrate is deformed. This means that the flatness of the substrate has been reduced.

If the two substrates are pressure bonded together with the flatness lowered in this way, the bonded substrate has a non-uniform substrate gap in which the central gap becomes narrower than the peripheral portion of the substrate. This leads to a deterioration of the quality of the substrate.
US Pat. No. 6,134,096 US Pat. No. 6,141,203

The present invention addresses the above-described problems, makes it possible to maintain the initial flatness of the adsorbed substrate regardless of the dynamic deformation of the processing chamber during the processing process, and to improve the quality of the substrate bonding process. This is the issue.

In order to solve the above-described problems, the present invention provides an electrostatic chuck device provided with a buffering means for reducing deformation transmitted to a substrate due to deformation of a chamber using an electrostatic chuck of a substrate bonding apparatus. provide.

Such a buffer means is configured by replacing the base portion of the conventional electrostatic chuck with an elastic material that can be elastically deformed without adding a separate device to the configuration of the substrate bonding apparatus, or the conventional base portion. The elastic material is added as a constituent element.

For this purpose, there is provided an electrostatic chuck device comprising an electrostatic chuck base portion having an elastic material layer and an electrostatic force generating portion comprising an insulating layer, an electrode layer, and a dielectric layer on the upper surface of the base portion.

Hereinafter, the improved characteristics of the elastic material layer according to the present invention will be described with reference to FIG.

In FIG. 3, the deformation of the chamber 10 due to an external force or the like is the same. Such deformation of the chamber is not uniform depending on the position, and shows a deviation. It has already been mentioned above that in the absence of buffering means, such deformation is transmitted to the substrate. The substrate support portion 20 provided with the buffer means provides an elastic restoring force to prevent such deformation and acts to disperse the external force to the surroundings. As a result, the substrate support portion 20 provided with the buffer means has a non-uniform stress distribution on one surface in contact with the chamber, and shows the same deformation corresponding to the deformed shape of the chamber, but the opposite surface attached to the substrate As the distance increases, the stress distribution becomes more uniform and the influence of local deformation decreases. Eventually, a uniform stress is applied to the substrate, and the initial flatness can be maintained.

As the elastic material used for the base of the electrostatic chuck, there is a material with excellent shape restoring force that restores the original shape when external force is removed, and a material that has little ripple effect of deformation around the local deformation preferable. On the other hand, the material must be stable and have good processability from various contamination sources during the processing process. Such a material is preferably urethane rubber.

The elastic material can be replaced with an appropriate one according to the deformation characteristics of the substrate to be adsorbed, the use conditions, and the like.

As described above, an elastic layer made of an elastic material is provided at the base of the electrostatic chuck, and non-uniform stress transmitted to the substrate due to chamber deformation or the like is made uniform by the elastic restoring force of the elastic material, thereby flattening the substrate. By improving, the quality of the adsorption substrate can be improved.

In particular, the present invention includes an elastic layer at the base of the electrostatic chuck, can be easily configured without adding a separate device to the substrate bonding apparatus, and achieves cost reduction.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments presented herein are provided so that the disclosed content will be thorough and complete, and will fully convey the spirit of the invention to those skilled in the art.

Hereinafter, various embodiments will be described to describe the electrostatic chuck structure of the present invention.

First, referring to FIG. 4A, a cross-sectional structure of an electrostatic chuck using urethane, which is an elastic material, as a base portion of the electrostatic chuck will be described as an embodiment of the present invention.

In FIG. 4a, the base 80 of the electrostatic chuck is made of a urethane elastic layer 81, and the electrostatic force generator 90 is located on the upper surface thereof. The electrostatic force generation unit 90 has a structure in which an insulating layer 91 made of a polyimide film, an electrode layer 92 made of a copper substrate, and a dielectric layer 93 made of a polyimide film are joined together by a joining film 95.

The shape of the base portion has various forms depending on the shape of the processed substrate, but generally has a rectangular block shape in the liquid crystal panel bonding step. The base portion thus processed is joined to the electrostatic force generating portion to form a cross section of the electrostatic chuck of the present invention. Although a method for supplying power to the electrode was not specifically shown, the electrode is generally connected to a DC power supply (not shown).

On the other hand, the electrostatic chuck may be fixed to a surface plate in the processing chamber by fastening means, and a number of lift pin holes may be formed that penetrate the electrostatic chuck.

4b and 4c show a cross-sectional structure of an electrostatic chuck according to another embodiment of the present invention.

The structure in which the electrostatic chuck base and the electrostatic force generator are located on the upper surface of the base is the same as described above. Below, description is abbreviate | omitted about the structure of an electrostatic force generation | occurrence | production part.

In FIG. 4b, the base portion has a two-layer structure having a urethane elastic layer 81 and an aluminum layer 82 on the upper surface thereof. By adding an aluminum layer, it is further effective to protect the electrostatic force generating part against deformation from the base part.

In FIG. 4c, the base portion has a two-layer structure having an aluminum layer 82 and a urethane elastic layer 81 on the upper surface thereof.

The arrangement and operation of the electrostatic chuck of the present invention in the substrate bonding apparatus will be described with reference to FIG.

FIG. 5 is a schematic view showing a substrate bonding apparatus according to an embodiment of the present invention.
The substrate bonding apparatus includes an upper chamber 11 and a lower chamber 12 in which an upper substrate P1 and a lower substrate P2 are attached. The lower chamber 12 is fixed to a base frame (not shown), and the upper chamber 11 is moved up and down by the lifting unit 40.

The upper chamber 11 is provided with an upper electrostatic chuck 21 for seating the upper substrate P1, and the lower chamber 12 is provided with a lower electrostatic chuck 22 for seating the lower substrate P2.

The upper electrostatic chuck 21 and the lower electrostatic chuck 22 are provided on an upper surface plate 31 provided in the upper chamber 11 and a lower surface plate 32 provided in the lower chamber 12, respectively.

The lower electrostatic chuck 22 is provided with a number of lift pins (Lift Pins) 321 that protrude through the lower surface plate 32.

When the lower substrate P2 positioned on the lower electrostatic chuck 22 is carried in, the lower lift pin 321 functions to raise and receive the lower substrate P2 and then lower and position the lower substrate P2 on the lower electrostatic chuck 22. When the process is completed and the upper substrate P1 on the upper side and the lower substrate P2 on the lower side are bonded to form a panel, the bonded substrate is raised in order to carry the bonded panel to the outside.

Further, the upper chamber 11 is provided with a camera 70 that can take an image of alignment marks displayed on the upper substrate P1 and the lower substrate P2 and confirm whether the substrate is placed at an accurate attachment fulcrum. It is done. The camera 70 photographs the alignment mark through the photographing hole 71 that penetrates the upper chamber 11.

Further, when a process space is formed in the upper chamber 11 and the lower chamber 12 by close contact, a high vacuum molecular pump (TMP) or a dry molecular pump (TMP) or a dry unit is used as a vacuum means 50 for forming the inside in a vacuum state. Pump (Dry
pump) are linked.

As the upper electrostatic chuck and the lower electrostatic chuck of the substrate bonding apparatus, an electrostatic chuck which is one of various embodiments of the present invention is provided to improve the flatness of the substrate surface. A conventional electrostatic chuck may be used as the lower electrostatic chuck of the lower chamber with relatively little deformation.

Below, the operation state of the board | substrate bonding apparatus which concerns on this invention of the structure mentioned above and the buffering function of the electrostatic chuck of this invention are demonstrated.

In a state where the upper chamber 11 and the lower chamber 12 are separated from each other, first, the upper substrate P1 is carried into a space between the upper chamber 11 and the lower chamber 12 by a substrate transfer robot (not shown). 11, the lift pin 311 provided in the lowering portion 11 descends, and the upper substrate P1 is attracted and raised.

The upper substrate P <b> 1 rising while being attracted by the lift pins 311 is attached to the upper electrostatic chuck 21 provided on the upper surface plate 31.

Further, the lower substrate P2 is carried in by the substrate transfer robot, the lift pins 321 are raised to receive the lower substrate P2, and the robot comes out to the outside while supporting the lower substrate P2. Thereafter, the lift pins 321 descend and are attached and attached to the lower electrostatic chuck 22.

Next, the upper chamber 11 is lowered by the elevating unit 40 and is brought into close contact with the lower chamber 12 to form a process space. When the process space is formed, a vacuum state is formed by the vacuum means 50. At this time, the upper surface plate 31 is lowered and the upper substrate P1 and the lower substrate P2 are roughly aligned.

After the rough alignment is performed, the fine alignment between the substrate P1 and the substrate P2 is performed, and the alignment is completed.

Such fine alignment mainly includes XYθ axis alignment for aligning alignment marks between the bonded substrates and Z axis alignment for adjusting the gap and parallelism between the bonded substrates.

Such alignment is performed with reference to the alignment mark of the substrate. When the final alignment is completed, the upper substrate P1 and the lower substrate P2 are in close proximity for bonding.

Thereafter, the power source is separated from the electrostatic chuck, and the upper substrate P1 is detached from the electrostatic chuck 21 and bonded to the lower substrate P2 positioned below.

When the upper substrate P1 and the lower substrate P2 are attached, the inside of the chamber 100 is evacuated to enter a standby state. At this time, although not shown, N2 gas is supplied on the upper chamber 11 side, and the upper substrate P1 and the lower substrate P2 are more firmly bonded.

When the above-described process is completed, the upper chamber 11 and the lower chamber 12 are separated from each other, the lift pins 321 of the lower chamber 12 are lifted, and a substrate transport robot enters from the outside and unloads the bonded substrates. Thus, the coalescence process is completed.

In the above process, the electrostatic chuck of the present invention buffers the chamber deformation caused by vacuum evacuation so as not to be transmitted to the substrate, and maintains the flatness of the substrate surface, thereby contributing to the improvement of the quality of the bonded substrates. .

It is sectional drawing which shows schematically the deformation | transformation of a chamber, and the deformation | transformation which acts on a board | substrate by it. It is a conceptual diagram which shows the fall of the flatness by deformation | transformation of a board | substrate. It is sectional drawing which shows that the deformation | transformation of the board | substrate by this invention reduces gradually. It is an electrostatic chuck sectional drawing concerning one example of the present invention. It is an electrostatic chuck sectional drawing concerning another example of the present invention. It is an electrostatic chuck sectional drawing concerning another example of the present invention. It is sectional drawing which showed roughly the board | substrate bonding apparatus provided with the electrostatic chuck.

Explanation of symbols

80 base,
81 Urethane layer 82 Aluminum layer 90 Electrostatic force generator 91 Insulating layer 92 Electrode layer 93 Dielectric layer 94 Copper electrode 95 Bonding film

Claims (5)

A base portion having an elastic layer made of an elastic material having elastic restoring force;
An electrostatic force generating part composed of an insulating layer, an electrode layer, and a dielectric layer located on the upper surface of the base part;
An electrostatic chuck device comprising: 2. The base portion according to claim 1, wherein the base portion has a two-layer structure including an elastic layer made of an elastic material having elastic restoring force and an inelastic layer made of an inelastic material located on one surface thereof. Electrostatic chuck device. 2. The electrostatic chuck device according to claim 1, wherein the elastic material of the elastic layer of the base portion is made of urethane. 4. The electrostatic chuck apparatus according to claim 2, wherein the elastic material of the elastic layer of the base portion is urethane, and the material of the inelastic layer is made of aluminum. In a substrate bonding apparatus provided with an electrostatic chuck as a substrate attaching means in the processing chamber,
A base portion having an elastic layer made of an elastic material having elastic restoring force;
An electrostatic force generating part composed of an insulating layer, an electrode layer, and a dielectric layer located on the upper surface of the base part;
A substrate bonding apparatus having an electrostatic chuck.