JP2009259891A - Device having electrostatic attraction function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device having an electrostatic attraction function of: reducing device breakage failure induced by leakage current; and preventing the occurrence of troubles such as deviation and cracking of a wafer by residual attraction force. <P>SOLUTION: The device is designed such that the leakage current flowing in an attracted sample when an electrostatic attraction voltage is applied is reduced to 0.1-15 μA/cm2 in unit area of the attracted sample and more preferably is designed such that the ratio of leakage current between electrostatic attraction electrodes flowing in an insulating layer to the leakage current flowing in the attracted sample when the electrostatic attraction voltage is applied is 0.1 or more. By designing the device, there can be provided the device having the electrostatic attraction function of: reducing the device breakage failure induced by the leakage current; and preventing the occurrence of troubles such as deviation and cracking of the wafer by the residual attraction force. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an apparatus having an electrostatic attraction function, and more specifically, has an electrostatic attraction function suitably used for a semiconductor wafer heating process in a semiconductor device manufacturing process or inspection process including a temperature raising process. Relates to the device.

  In the past, a heater wound with a metal wire has been used for heating a semiconductor wafer in a semiconductor device manufacturing process. However, when such a heater is used, there has been a problem of metal contamination on the semiconductor wafer, and in recent years, the use of a ceramic integrated wafer heating apparatus using a ceramic thin film as a heating element has been proposed ( For example, refer to JP-A-4-124076 (Patent Document 1).

  Among them, as a method of heating a wafer in molecular beam epitaxy, CVD, sputtering, or the like, there is no outgas from the inside of the substrate, and high-purity and thermal shock-resistant pyrolytic boron nitride (PBN) and pyrolytic graphite (PG) are used. It is effective to use a composite ceramic heater (see Japanese Patent Laid-Open No. 63-241922 (Patent Document 2)), and using such a heater is easier to install than conventional tantalum wire heaters, There is also an advantage that it is easy to use because it does not cause troubles such as thermal deformation, disconnection, and short circuit, and that it is relatively easy to obtain heat uniformity because it is a surface heater.

  In order to fix the semiconductor wafer on the heater during the heating of the semiconductor wafer, an electrostatic adsorption device is used in a reduced-pressure atmosphere, and the material has shifted from resin to ceramics as the temperature of the process increases. (See Kaisho 52-67353 (Patent Document 3) and JP-A-59-124140 (Patent Document 4)).

  In recent years, an "apparatus having an electrostatic adsorption function" in which these ceramic-integrated wafer heating apparatus and an electrostatic adsorption apparatus are combined has been proposed. For example, it is used in a low temperature region such as an etching process. As a material using alumina in the insulating layer of an electrostatic adsorption device (see New Ceramics (7), p49-53, 1994 (Non-Patent Document 1)) Those using pyrolytic boron nitride as the insulating layer of the electrostatic adsorption device (Japanese Patent Laid-Open No. 4-358074 (Patent Document 5), Japanese Patent Laid-Open No. 5-109876 (Patent Document 6), Japanese Patent Laid-Open No. 5-129210 (See Patent Document 7) and Japanese Patent Laid-Open No. 7-10665 (Patent Document 8)) have been reported.

  By the way, in recent years, electrostatic adsorption devices made of ceramics have been mounted on molecular beam epitaxy devices, CVD devices, or sputtering devices. However, as described in Non-Patent Document 1, electrostatic adsorption devices are used. The force becomes stronger as the volume resistivity of the insulating layer provided in the electrostatic adsorption device becomes lower. On the other hand, if it is too low, the device may be damaged by a leakage current.

There is also known a phenomenon in which after the wafer is sucked and processed, the wafer is attracted to the surface of the electrostatic chuck by the residual attracting force. When such a phenomenon occurs, when the wafer is lifted with lift pins or the like, a trouble occurs that the wafer is displaced or the wafer is cracked. In particular, when an oxide film is formed on the surface of the wafer, such a phenomenon tends to occur remarkably. However, in recent years, since the thickness of the oxide film provided on the wafer has increased, the above-mentioned trouble is frequently caused. Has occurred.
JP-A-4-124076 Japanese Unexamined Patent Publication No. 63-241922 JP 52-67353 A JP 59-124140 A Japanese Patent Laid-Open No. 4-358074 JP-A-5-109876 JP-A-5-129210 Japanese Patent Laid-Open No. 7-10665 New Ceramics (7), p49-53, 1994

  The present invention has been made in view of such problems, and the object of the present invention is to reduce the failure of the device due to the leakage current, and to prevent the occurrence of troubles such as wafer misalignment and cracking due to the residual adsorption force. An object of the present invention is to provide an apparatus having an electrostatic adsorption function that can be prevented.

In order to solve such a problem, the present invention is an apparatus having an electrostatic attraction function having an electrostatic attraction electrode, a heating element, and an insulating layer, which is covered when an electrostatic attraction voltage is applied. The leakage current flowing to the adsorption sample side is 0.1 to 15 μA / cm ² in terms of unit area of the sample to be adsorbed.

  Preferably, a ratio of a leakage current between the electrodes for electrostatic adsorption flowing in the insulating layer and a leakage current flowing to the sample to be adsorbed when an electrostatic adsorption voltage is applied is 0.1 or more.

Preferably, the insulating layer is made of any one material selected from the group consisting of silicon nitride, a mixture of boron nitride and aluminum nitride, alumina, aluminum nitride, and pyrolytic boron nitride, and has a content of 0.001 to 20 wt%. The volume resistivity is adjusted to be in the range of 10 ⁸ to 10 ¹⁴ Ωcm by containing impurities in the range of 1 to 10.

In the present invention, the apparatus is designed so that the leakage current flowing to the sample to be adsorbed when applying the electrostatic adsorption voltage is 0.1 to 15 μA / cm ^{2 in} terms of unit area of the sample to be adsorbed, more preferably The device should be designed so that the ratio of the leakage current between the electrodes for electrostatic adsorption flowing in the insulating layer and the leakage current flowing to the sample to be adsorbed when an electrostatic adsorption voltage is applied is 0.1 or more. Therefore, it is possible to provide an apparatus having an electrostatic attraction function that can reduce the failure of the device due to the leak current and can prevent the occurrence of troubles such as wafer displacement and cracking due to the residual attraction force.

  The structure of the apparatus of the present invention will be described below with reference to the drawings. However, the present invention relates to the above-described conventional problems (problems such as device breakage failure due to leakage current and occurrence of wafer displacement and cracking due to residual adsorption force). ) The knowledge obtained as a result of the examination of the present inventors about the solution method, that is, the leakage current flowing to the wafer side (adsorbed sample side) when an electrostatic adsorption voltage is applied is within an appropriate range, Furthermore, sufficient wafer adsorption is ensured by optimizing the leakage current between the chuck terminals (between the electrodes for electrostatic adsorption) flowing in the insulating layer with respect to the leakage current to the wafer side (sample to be adsorbed). In addition, this is based on the knowledge that the device breakage failure due to the leakage current can be reduced and the inconvenience caused by the residual adsorption force can be suppressed.

Specifically, in the apparatus of the present invention, when an electrostatic adsorption voltage is applied, the leakage current flowing to the sample to be adsorbed is 0.1 to 15 μA / cm ^{2 in} terms of unit area of the sample to be adsorbed. Designed to. Within such a leakage current range, it is ensured that a sufficient electrostatic attraction force due to the Johnson Rabeck force is generated, and it is possible to prevent the occurrence of device insulation failure.

In addition, when the leak current is less than 0.1 μA / cm ² , a sufficient electrostatic adsorption force cannot be obtained. Further, when the leakage current exceeds 15 μA / cm ² , the occurrence of defective insulation of the device becomes remarkable. The more preferable leakage current is 0.5 to 10 μA / cm ² .

  In the apparatus of the present invention, the ratio between the leakage current between the electrodes for electrostatic adsorption flowing in the insulating layer and the leakage current flowing to the sample to be adsorbed when an electrostatic adsorption voltage is applied is 0.1 or more. Designed to be When the two are in such a relationship, a current easily flows between the electrostatic chucking electrodes (between the chuck terminals), so that no charge remains in the insulator between the chuck terminals and no residual chucking occurs. As a result, it is understood that the wafer can be quickly released when the adsorption process of the sample to be adsorbed (wafer) is completed and the wafer is lifted by lift pins after the applied voltage is reduced to zero.

  If the above leakage current ratio is less than 0.1, it is difficult for current to flow between the chuck terminals, and charges remain in the vicinity of the chuck terminals, and when the wafer is released due to the residual adsorption force caused by the remaining charges. Wafer displacement occurs, or in the worst case, wafer cracking occurs. The more preferable leakage current ratio is 0.5 or more.

  Here, the current that flows to the sample to be adsorbed (wafer side) is the voltage between the chuck terminals when the sample to be adsorbed (wafer) is adsorbed by applying a voltage between the electrodes for electrostatic adsorption (between the chuck terminals). It means the value obtained by measuring and subtracting the current that flows when the same voltage is applied with no wafer placed, from the value of the measured current. Further, the current flowing in the insulating layer means the latter (current flowing when the same voltage is applied with no wafer mounted).

  The sample to be adsorbed (wafer) is, for example, a silicon wafer having a diameter of 300 mm (12 inches), and a silicon wafer with an oxide film in which an oxide film having a thickness of 100 to 300 μm is coated on the main surface. In the example, such a wafer is used.

The leakage current between the electrostatic adsorption electrodes flowing in the insulating layer can be controlled by the manufacturing conditions of the insulating layer. In the present invention, in order to obtain the above leakage current ratio, it is made of any one material selected from the group consisting of silicon nitride, a mixture of boron nitride and aluminum nitride, alumina, aluminum nitride, and pyrolytic boron nitride. An insulating layer that contains impurities in the range of 001 to 20 wt% and has a volume resistivity adjusted to a range of 10 ⁸ to 10 ¹⁴ Ωcm is used.

  When manufacturing such an insulating layer by chemical vapor deposition (CVD), the leakage current flowing in the wafer and the insulating layer are changed by changing the production conditions such as the type of source gas, reaction temperature, and pressure. It is possible to control the ratio of the leakage current between the chuck terminals flowing through. For example, increasing the reaction temperature increases the impurity content and further improves the film orientation of the insulating layer. Conversely, by lowering the reaction temperature, the impurity content is reduced and the film orientation of the insulating layer is lowered. Similarly, when an insulating layer is formed by sputtering, the ratio between the leakage current flowing on the wafer side and the leakage current between chuck terminals flowing in the insulating layer can be controlled by adjusting the manufacturing conditions.

  Hereinafter, the device of the present invention will be specifically described with reference to Examples (and Comparative Examples), but the present invention is not limited to these Examples.

  FIG. 1 is a schematic diagram for explaining an example of a manufacturing process of an apparatus according to the present invention. First, a mixture of ammonia and boron trichloride is reacted under the conditions of 1800 ° C. and 100 Torr to obtain a diameter of 300 mm and a thickness of 20 mm. Then, pyrolytic boron nitride (2b) is produced on the graphite base (2a) to form a pyrolytic boron nitride-coated graphite base, and then methane gas is supplied at 1800 ° C., 5 Torr on the pyrolytic boron nitride-coated graphite base. A pyrolytic graphite layer (2c) having a thickness of 100 μm was formed under the above conditions to obtain a supporting substrate (2) (FIG. 1 (A)).

  Further, pyrolytic graphite layers (3, 4) are formed on the front and back surfaces of the pyrolytic graphite layer (2c) (FIG. 1 (B)), and these pyrolytic graphite layers (3, 4) are patterned. A bipolar electrode for electrostatic adsorption (3a, 3b) and a heating element (4) were obtained (FIG. 1C).

  Subsequently, an insulating layer (5) made of pyrolytic boron nitride containing boron carbide having a thickness of 200 μm is formed on both surfaces of the support substrate (2), and then the insulating layer (5) serving as the wafer adsorption surface is mirror polished. Thus, an apparatus (1) having an electrostatic attraction function according to the present invention was produced (FIG. 1D).

  In forming the insulating layer (5) made of pyrolytic boron nitride containing boron carbide, a mixture of ammonia, boron trichloride, methane, and boron trichloride is used, and the methane flow rate is 10% in terms of the ratio of ammonia. A plurality of samples were prepared by changing the range of ˜50%. The reaction temperature is also changed in the range of 1700 to 1850 ° C. The reaction was carried out under a condition where the reaction pressure was constant at 5 Torr.

  For an apparatus having an electrostatic adsorption function including an insulating layer formed under the above reaction conditions, a 300 mm diameter silicon wafer with an oxide film (film thickness 300 μm) is electrostatically adsorbed by applying an electrostatic adsorption voltage of ± 300V. , The leakage current flowing on the wafer side when heated to 200 ° C. (converted per unit area of the wafer) and the leakage current between the chuck terminals flowing in the insulating layer are measured, and the device insulation and the wafer position when the wafer is released I investigated the gap. The results are summarized in Tables 1 and 2.

From the results shown in Table 1, the samples (samples 2 to 6) in which the leakage current flowing to the sample to be adsorbed when applying the electrostatic adsorption voltage is 0.1 to 15 μA / cm ² in terms of the unit area of the wafer. ) Shows that there is no problem in adsorptivity and device insulation.

  Further, from the results shown in Table 2, the leakage current ratio described above (the leakage current between the electrostatic adsorption electrodes flowing in the insulating layer and the leakage current flowing on the wafer side when the electrostatic adsorption voltage is applied) If the ratio is 0.1 or more, it is understood that there is no wafer position shift at the time of wafer release.

Therefore, the apparatus is designed so that the leakage current flowing to the sample to be adsorbed when applied with the electrostatic adsorption voltage is 0.1 to 15 μA / cm ^{2 in} terms of the unit area of the sample to be adsorbed, and more preferably the insulation By designing the apparatus so that the ratio of the leakage current between the electrodes for electrostatic adsorption flowing in the layer and the leakage current flowing to the sample to be adsorbed when an electrostatic adsorption voltage is applied is 0.1 or more, There is provided an apparatus having an electrostatic attraction function that can reduce device breakage failure due to leakage current and can prevent occurrence of trouble such as wafer displacement and cracking due to residual attraction force.

  According to the present invention, there is provided an apparatus having an electrostatic attraction function capable of reducing device damage failure due to leakage current and preventing troubles such as wafer displacement and cracking due to residual attraction force.

It is the schematic for demonstrating the example of a manufacturing process of the apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrostatic adsorption apparatus support base material 2 Support base material 3a, 3b Electrode for bipolar electrostatic adsorption 4 Heating element 5 Insulating layer

Claims (3)

An apparatus having an electrostatic adsorption function having an electrostatic adsorption electrode, a heating element, and an insulating layer, and a leak current flowing to the adsorbed sample side when an electrostatic adsorption voltage is applied is a unit area of the adsorbed sample An apparatus having an electrostatic adsorption function, characterized in that it is 0.1 to 15 μA / cm ² in terms of hit.   The ratio between the leakage current between the electrodes for electrostatic adsorption flowing in the insulating layer and the leakage current flowing to the sample to be adsorbed when an electrostatic adsorption voltage is applied is 0.1 or more, An apparatus having an electrostatic attraction function according to claim 1. The insulating layer is made of any one material selected from the group consisting of silicon nitride, a mixture of boron nitride and aluminum nitride, alumina, aluminum nitride, and pyrolytic boron nitride, and has an impurity in the range of 0.001 to 20 wt%. The apparatus having an electrostatic attraction function according to claim 1, wherein the volume resistivity is adjusted to be in a range of 10 ⁸ to 10 ¹⁴ Ωcm.