KR20030094493A - Chuck for supporting a substrate - Google Patents

Abstract

PURPOSE: A chuck for supporting a substrate is provided to be capable of preventing porosities from being generated inside of a predetermined layer and restraining the bubble phenomenon of a lower layer. CONSTITUTION: A chuck(100) for supporting a substrate is provided with a body part(110) for supporting the substrate, the first coating layer(120) made of the first ceramic, formed on the surface of the body part, and the second coating layer(130) formed at the upper portion of the first coating layer for contacting the substrate. At this time, a plurality of buffer layers(132) and ceramic layers(134), are alternately stacked with each other for forming the second coating layer. At the time, the buffer layer is made of conductive layer and the ceramic layer is made of the second ceramic. Preferably, a concave portion is formed at one side of the body part corresponding to the size of the substrate and the second coating layer is formed at the concave portion of the body part.

Description

Chuck for supporting a substrate

The present invention relates to an electrostatic chuck. More particularly, the present invention relates to an electrostatic chuck for supporting a semiconductor substrate and fixing it using an electrostatic force in a manufacturing process of the semiconductor device.

Recently, the manufacturing technology of semiconductor devices has been developed to improve the degree of integration, reliability, response speed, etc. in order to meet various needs of consumers. Generally, a semiconductor device is manufactured by forming a predetermined film on a silicon semiconductor substrate used as a semiconductor substrate and forming the film in a pattern having electrical properties.

The pattern is formed by sequential or repeated performance of unit processes such as chemical vapor deposition, sputtering, photolithography, etching, ion implantation, chemical mechanical polishing (CMP), and the like. In such unit processes, a chuck for supporting and fixing a semiconductor substrate is used. In recent years, in the semiconductor substrate processing technology which requires miniaturization and large capacity of the semiconductor device, the method of fixing the semiconductor substrate is also greatly changed as the sheet processing and the dry processing are preferred. In other words, in the conventional case, the clamping or vacuum was used to fix the semiconductor substrate. However, in recent years, the semiconductor substrate is fixed by using electrostatic force and at the same time providing a temperature control gas for maintaining a constant temperature of the semiconductor substrate. Electrostatic chucks (ESC) are mainly used. The use range of the electrostatic chuck has been extended to overall semiconductor substrate processing processes such as chemical vapor deposition, etching, sputtering, ion implantation processes, and the like.

As an example of the electrostatic chuck, US Patent No. 6,134,096 (issued Yamada et al) discloses an electrostatic chuck consisting of an insulating layer, an electrode layer, and a dielectric layer for adsorbing a wafer by using electrostatic force. An electrostatic chuck is disclosed in which a capacitor plate having a plurality of structures is formed to adsorb a wafer by electrostatic force.

Currently, the most commonly used electrostatic chuck is a polymide type electrostatic chuck. However, a major problem of the polyimide material is that it has low dielectric constant and thermal conductivity compared to other materials at weak durability and the same thickness. In addition, due to the weak durability, the dielectric layer is easily broken, and the electrode is exposed to the plasma or the semiconductor substrate for processing the semiconductor substrate, thereby making it unusable.

In the case of the electrostatic chuck using a ceramic plate as the dielectric, a silicon (Si) -based adhesive is used to bond the ceramic plate to the aluminum body, and in the case of dry etching, there is no problem because the process temperature is low, but high density plasma (high density) Plasma; HDP) deposition process does not fix the semiconductor substrate by using electrostatic force, but it is used by attaching ceramic plate to aluminum body because bias power is applied. There is a problem that can not be used. Therefore, in the case of high density plasma deposition process, an indium (In) -based adhesive is used as the adhesive. However, in the process of cleaning the inside of the chamber of the high density plasma deposition apparatus using the fluorine (F) group, the fluorine group and the indium react to weaken the bonding force between the aluminum body and the ceramic plate. This causes a problem that the ceramic plate is peeled or broken, and indium flows outward to generate an arc in the high density plasma deposition process. In addition, since the aluminum body and the ceramic plate are not uniformly bonded, it is not easy to uniformly control the temperature of the semiconductor substrate during the process, and there is a problem in that fine displacement of the ceramic plate occurs due to the flow of indium.

Meanwhile, in the high density plasma deposition process, an oxide film (SiO ₂ ) is formed on a semiconductor substrate using a silane (SiH ₄ ) gas and an oxygen (O ₂ ) gas. In this case, an inert gas such as helium (He) or argon (Ar) is provided together, and etching is performed by sputtering of inert gas ions together with deposition of an oxide film according to application of a bias power provided from the bottom of the chamber. In this case, when the metal wiring layer is formed on the semiconductor substrate, the deposition portion formed by the metal wiring layer has a larger etching rate than deposition, and the flat portion has a larger deposition rate than etching, so that the deposition is flat. Here, the change of the deposition rate and the sputtering ratio causes a large change in the lower film quality formed on the semiconductor substrate. When the sputtering ratio is low, an overhang occurs on the substrate and pores are generated in the formed film. In the case where the sputtering ratio is high, as the amount of incident ions increases, a bubble phenomenon occurs in which the lower film is lifted.

SUMMARY OF THE INVENTION An object of the present invention for solving the above problems is to provide a chuck for supporting a substrate which is manufactured by a spray coating method and prevents the generation of pores in the formed film and the bubble shape of the lower film.

1 is a schematic diagram illustrating a chuck for supporting a substrate according to an embodiment of the present invention.

FIG. 2 is a perspective view illustrating the aluminum body illustrated in FIG. 1.

FIG. 3 is a view for explaining an equivalent circuit between the chuck and the plasma for supporting the substrate shown in FIG. 1.

4 is a diagram for explaining an equivalent circuit of a ceramic plate type chuck.

FIG. 5 is a diagram for explaining an equivalent circuit of a general spray coating chuck.

Explanation of symbols on the main parts of the drawings

10 plasma 20 sheath zone

30: semiconductor substrate 40: bias power

100: Chuck 110: Aluminum body

112: recess 120: first coating layer

130: second coating layer 132: buffer layer

134: ceramic layer

The present invention for achieving the above object is a body for supporting a substrate, a first coating layer formed on the surface of the body, made of a first ceramic material, and the substrate on one surface of the body adjacent to the substrate And a second coating layer formed on the one coating layer and in contact with the substrate, wherein the second coating layer is formed repeatedly of a buffer layer made of a conductive material and a ceramic layer made of a second ceramic material.

The body and the conductive material may be made of aluminum, and the first ceramic material and the second ceramic material may be made of aluminum oxide (Al ₂ O ₃ ). In addition, the first coating layer and the second coating layer is formed by a thermal spray coating method does not require an adhesive of silicon or indium.

The ceramic layers of the first coating layer and the second coating layer each act as a capacitor, and the total capacitance is reduced due to the series connection, thereby reducing the incident energy of ions. Therefore, the sputtering of ions is reduced and the bubble phenomenon of the lower film quality formed on the semiconductor substrate is prevented.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic diagram illustrating a chuck for supporting a substrate according to an embodiment of the present invention, and FIG. 2 is a perspective view illustrating the aluminum body illustrated in FIG. 1.

1 and 2, the chuck 100 for supporting the illustrated substrate (not shown) includes an aluminum body 110 having a disk shape and a first coating layer 120 formed on the surface of the aluminum body 110. ) And a second coating layer 130 formed on the first coating layer 120 on one surface of the aluminum body 110 supporting the semiconductor substrate.

A concave portion 112 corresponding to the size of the semiconductor substrate is formed on one surface of the aluminum body 110 supporting the semiconductor substrate. The depth of the recess 112 is determined according to the thickness of the second coating layer 130.

The first coating layer 120 is formed on the entire surface of the aluminum body 110, and is formed by thermal spray coating of aluminum oxide powder.

The second coating layer 130 is formed by thermal spray coating on the first coating layer 120 in the recess 112 of the aluminum body 110. In the second coating layer 130, a buffer layer 132 made of aluminum and a ceramic layer 134 made of aluminum oxide are repeatedly formed. That is, the buffer layer 132 is formed on the first coating layer, the ceramic layer 134 is formed on the buffer layer 132, and the buffer layer 132 is formed on the ceramic layer 134 again. As described above, the ceramic layer 134 is finally formed. That is, the semiconductor substrate is seated on the finally formed ceramic layer 134. As described above, in the case of forming a ceramic dielectric layer by thermal spray coating on the surface of the aluminum body 110, an electrode is not formed separately, and the aluminum body 110 itself is used as an electrode.

In the case of coating the ceramic layer 134 as described above, if the coating proceeds to a predetermined thickness or more, a large number of pores are formed on the upper portion of the coating layer, and a phenomenon in which the coating layer is not maintained cannot be maintained. Therefore, it is preferable to repeatedly form a plurality of layers as described above. At this time, in order to maintain the shape and physical properties of the ceramic layer 134, it is preferable to form a buffer layer 132 between each ceramic layer, and preferably formed of aluminum having excellent bonding strength with the ceramic.

On the other hand, since the most stable coating thickness of the ceramic layer 134 made of aluminum oxide is about 300 μm, the thickness of each ceramic layer 134 is preferably about 250 to 350 μm, and the thickness of the aluminum buffer layer 132. The thickness of the ceramic layer 134 is preferably about 10 to 100 μm. When the thickness of the aluminum buffer layer 132 is 10 μm or less, the shape and physical properties of the ceramic layer 134 are not easily maintained, and when the thickness of the aluminum buffer layer 132 is 100 μm or more, lamination is not efficient.

FIG. 3 is a view for explaining an equivalent circuit between the chuck and the plasma for supporting the substrate shown in FIG. 1.

Referring to FIG. 3, the bias power 40 is applied to the aluminum body 110, and the plasma 10 formed inside the high density plasma deposition chamber (not shown) serves as a resistance. The ceramic layers 134 of the first coating layer 120 and the second coating layer 130 formed on the surface of the aluminum body 110 each function as a capacitor and are mounted on the second coating layer 130. Also serves as a capacitor.

An upper electrode of the chamber is provided with an upper electrode for forming a reaction gas provided into the chamber in a plasma state. Radio frequency (RF) power is applied to the upper electrode to form the reaction gas in a plasma state, and a bias power 40 is applied to the aluminum body 110 to guide the plasma 10 onto the semiconductor substrate. .

At this time, ions among electrons and ions which move randomly in the plasma 10 are accelerated to the semiconductor substrate 30 under the influence of the bias power 40 while electrons are repulsed. That is, a potential barrier exists between the plasma 10 and the semiconductor substrate 30, which is called a sheath. The sheath zone 20 appears dark due to the low electron density, and the width of the sheath zone 20 depends on the bias voltage 40 and the ionization density of the plasma 10. That is, a negative potential is formed at the portion of the semiconductor substrate 30 by the bias power 40, and equipotential is maintained at the portion of the plasma 10.

As described above, due to the potential difference between the portion of the plasma 10 and the semiconductor substrate 30, electrons in the plasma 10 are repelled, and ions are accelerated to the semiconductor substrate 30. In this case, the potential difference determines the energy of the ions colliding with the surface of the semiconductor substrate 30, and the collision energy of the ions determines the etching rate of the semiconductor substrate 30.

In the illustrated equivalent circuit, the sheath region 20 also serves as a capacitor on the equivalent circuit, and the total capacitance Ct is formed on the surface of the semiconductor substrate Cw and the sheath region Cs and the chuck 100. (C1) and a plurality of ceramic layers (C2, C3, C4).

On the other hand, in general, the capacitance C of the dielectric layer formed on the chuck is determined by the following equation (1).

C = ε * A / D (ε: dielectric constant, A: electrode plate area, D: distance between electrode plate) ---- (1)

In Equation (1), D means the thickness of the dielectric layer. Therefore, as the thickness of the dielectric layer becomes thinner, the capacitance C becomes relatively large, and the impedance Z is inversely proportional to the capacitance C. Therefore, in the total voltage drop, the capacitance of the dielectric layer The voltage drop over is relatively small. Accordingly, the potential difference of the sheath zone becomes relatively large, and the incident energy of the ions becomes relatively large. This causes the sputtering of ions to become relatively large. That is, an increase in the sputtering of ions causes a bubble phenomenon of the lower film quality. The difference in sputtering ratio as described above is shown in Table 1.

TABLE 1

Ceramic Plate Method (4mm Thickness) Thermal spray coating method (thickness 0.3mm) Sputtering degree 830 yen 970 yen

Referring to Table 1, in the case of the ceramic plate method, the thickness of the dielectric layer may be increased, whereas in the case of the spray coating method, the thickness of the dielectric layer is limited. If there is a difference in thickness as described above, the degree of sputtering of ions is changed depending on the thickness of the dielectric layer, and the bubble phenomenon of the lower film quality increases when the sputtering of ions increases.

4 is a view for explaining an equivalent circuit for a ceramic plate type chuck, Figure 5 is a view for explaining an equivalent circuit for a general thermal spray coating chuck.

3 to 5, in the ceramic plate method 200, since the thickness of the ceramic plate 250 is thicker than the ceramic layer 350 of the thermal spray coating method 300, the capacitance of the ceramic plate 250 is greater. small. Therefore, when the chuck of the thermal spray coating method 300 is used, a bubble phenomenon may occur in the lower film quality of the semiconductor substrate, and in the case of the ceramic plate method 200, a problem due to indium used as an adhesive may occur.

On the contrary, since the first coating layer 120 and the multilayered second coating layer 130 shown in FIG. 1 are formed by thermal spray coating, no adhesive is required, and the first coating layer 120 and the second coating layer 130 Since the ceramic layers 134 each function as a capacitor, the total capacitance Ct is reduced by the following equation (2).

1 / Ct = 1 / C1 + 1 / C2 + 1 / C3 + 1 / C4 ---- (2)

As described above, since the total capacitance Ct of the chuck becomes small, the impedance is relatively increased, which leads to a decrease in the sputtering of ions. Here, as shown, the ceramic layer 134 including the first coating layer 120 is composed of all four layers, but the degree of lamination may be variously changed according to the process conditions. That is, pores do not occur in the film to be formed, and may be appropriately changed to prevent bubble phenomenon in the lower film quality.

According to the present invention as described above, the ceramic layers of the first coating layer and the second coating layer formed on the chuck each function as a capacitor, thereby reducing the total capacitance. As a result, sputtering of ions accelerated to the semiconductor substrate is reduced, thereby preventing bubble phenomenon in the lower film formed on the semiconductor substrate.

In addition, unlike the conventional ceramic plate, since the first coating layer and the second coating layer are formed by the thermal spray coating method, an adhesive is unnecessary, and problems such as arc generation and breakage of the dielectric layer by the adhesive are eliminated.

Thus, a stable deposition process is ensured and a uniform film can be formed on the semiconductor substrate.

Although described above with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below I can understand that you can.

Claims (6)

A body for supporting the substrate; A first coating layer formed on a surface of the body and made of a first ceramic material; And A second coating layer formed on one surface of the body adjacent to the substrate to be in contact with the substrate and having a buffer layer made of a conductive material and a ceramic layer made of a second ceramic material repeatedly formed. Chuck for supporting a substrate to be made. The method of claim 1, wherein the substrate has a first size, and one side of the body is formed with a recess having a second size corresponding to the first size, And the second coating layer is formed in the concave portion. The chuck of claim 1, wherein the first coating layer and the second coating layer are formed by thermal spray coating. The chuck of claim 1, wherein the conductive material comprises aluminum. The chuck of claim 1, wherein the first ceramic material and the second ceramic material comprise aluminum oxide. The chuck of claim 1, wherein the ceramic layer has a thickness of 250 to 350 μm and the buffer layer has a thickness of 10 to 100 μm.