JP3887582B2 - Sputtering equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sputtering apparatus, and more particularly to a sputtering apparatus provided with a deposition preventing plate that prevents an insulator or the like from adhering to the wall surface of the vacuum vessel. Note that the present invention can be applied not only to a sputtering apparatus but also to a CVD apparatus, a PVD apparatus, and a dry etching apparatus.
[0002]
[Prior art]
In the manufacturing process of an IC (semiconductor integrated circuit), various dielectric films are formed. The purpose of use is often for an interlayer insulating film, etching, mask for selective ion implantation or selective electrode formation, passivation, capacitor dielectric film, and the like. A material or a plasma processing method is selected for each purpose, and various processing methods such as CVD, dry etching, and sputtering are used.
[0003]
In recent years, in order to reduce the size of an IC, it has been studied to perform plasma treatment of a high dielectric material such as barium strontium titanate (BST) or strontium titanate (STO) on a dielectric film of a capacitor.
[0004]
Further, plasma processing of ferroelectric materials such as lead zirconate titanate (PZT) and strontium bismastantalate (SBT) has been studied for sensors, actuators, and nonvolatile memory devices.
[0005]
Hereinafter, among the various processes described above, a conventional sputtering apparatus will be described in particular.
[0006]
FIG. 5 is a longitudinal sectional view showing a schematic configuration of a conventional sputtering apparatus. In this sputtering apparatus, a sputtering chamber is formed by a vacuum chamber 51 that can be evacuated, and a target 52 is placed on an electrode 53 below the sputtering chamber. It is held fixed. The electrode 53 is electrically insulated from the vacuum vessel 51, and the electrode 53 incorporates a water cooling mechanism (not shown) in order to prevent the temperature of the target 52 from rising.
[0007]
Above the vacuum vessel 51, a wafer holder 54 is arranged in parallel to face the electrode 53. The wafer holder 54 is electrically insulated from the vacuum vessel 51 and has a floating potential. A substrate, for example, a semiconductor wafer (hereinafter referred to as a wafer) 55 is placed on the wafer holder 54. The wafer holder 54 incorporates a heating mechanism (not shown) for maintaining the wafer 55 at a predetermined temperature set in advance.
[0008]
A predetermined high-frequency power determined by sputtering conditions is applied between the electrode 53 and the grounded vacuum vessel 51 under a predetermined negative DC bias by a high-frequency power source 56.
[0009]
In order to perform the film forming process with this sputtering apparatus, the wafer 55 is placed on the wafer holder 54, evacuated by a vacuum pump connected to an exhaust port (not shown), and then a predetermined gas (for example, Ar gas) from the gas introduction port. Is adjusted to a predetermined pressure by adjusting a variable conductance valve interposed between the exhaust port and the vacuum pump. Then, high frequency power is applied to generate plasma to sputter the target.
[0010]
Therefore, components scattered from the target 52 are deposited on the wafer 55 to form a film. The components scattered from the target 52 are not only directed toward the wafer 55 but also directed in other directions. If an object other than the wafer 55 adheres to the inner wall of the vacuum vessel 51 or a structure inside the vacuum vessel 51, cleaning becomes difficult. Therefore, an adhesion preventing plate 57 is disposed so as to surround the electrode 53 and the wafer holder 54. Yes.
[0011]
The adhesion prevention plate 57 is made of metal and is electrically connected to the vacuum vessel 51 to be at a ground potential. When the sputtered material attached to the surface is made thick and easy to attach / detach, it can be removed and cleaned. I have to. Further, the deposition preventing plate 57 can be partially retracted for loading and unloading the wafer 55, although not shown.
[0012]
[Problems to be solved by the invention]
When a dielectric material, particularly a high-ferroelectric material, is generated during plasma processing in such a conventional sputtering apparatus equipped with an adhesion prevention plate, an insulator is formed on the surface of the adhesion prevention plate and a ground plane is formed. It may disappear. In such a state, the plasma spreads out from the gap between the deposition preventing plates and discharges toward the wall surface of the vacuum vessel where no film is attached. In such a state, it becomes impossible to perform plasma processing stably.
[0013]
Further, when processing a plurality of wafers continuously, there is a problem that even wafers other than the wafer to be processed are exposed to plasma and become defective.
[0014]
In addition, although it is conceivable to install the protective plates in a double manner, there is a problem that electric discharge occurs between the two protective plates.
[0015]
In addition, the adhesion-preventing plate on which the adhesion film is formed must be regularly maintained, and it is desired to extend the maintenance cycle from the viewpoint of work efficiency.
[0016]
The present invention solves the above-mentioned conventional problems, and can prevent the plasma from spreading outside from the space surrounded by the deposition preventive plate by attaching an insulator to the deposition preventing plate. In addition, the present invention provides a sputtering apparatus that can prevent discharge between two deposition preventing plates when the deposition preventing plates are doubled. Furthermore, the present invention provides a sputtering apparatus capable of extending the maintenance cycle for the deposition preventing plate, and provides a sputtering apparatus capable of preventing the plasma state from changing over time.
[0017]
[Means for Solving the Problems]
In order to achieve the above object, the invention described in claim 1 includes a vacuum vessel capable of maintaining a vacuum, a wafer holder in the vacuum vessel, on which a wafer to be processed by plasma is placed, and In a sputtering apparatus comprising a power source for applying electric power to an electrode disposed opposite to a wafer holder and an adhesion preventing plate disposed so as to surround the electrode, the adhesion preventing plate is made of a metal material in a double Installed in a non-contact state, set the outer protective plate to ground potential, the inner protective plate to DC negative potential, and the distance between the facing surfaces of the inner and outer protective plates to be different. With this configuration, the plasma can be prevented from spreading out of the deposition preventing plate, and the plasma treatment can be performed stably. Further, it is possible to prevent wafers other than the wafer to be processed from being exposed to plasma. In addition, the plasma treatment can be performed while removing the adhered insulator by setting the outer adhesion plate to the ground potential and the inner adhesion plate to the DC negative potential, thereby extending the maintenance cycle of the adhesion plate. be able to.
[0018]
According to a second aspect of the present invention, in the sputtering apparatus according to the first aspect, in the double anti-adhesion plate, the inner surface of the inner anti-adhesion plate is covered with an insulator, It is possible to prevent an insulating material from adhering and change the plasma state over time, and plasma processing can be performed stably.
[0019]
According to a third aspect of the present invention, in the sputtering apparatus according to the first or second aspect, the plasma treatment is a sputtering treatment for forming a dielectric thin film or a ferroelectric thin film.
[0020]
According to a fourth aspect of the present invention, the sputtering apparatus according to the first, second, or third aspect further includes a moving unit on which a plurality of wafers are placed, and the wafers are sequentially moved to a processing position to be processed continuously. This configuration makes it possible to automatically process a plurality of wafers.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the present invention will be described below with reference to the drawings. In the following description, members corresponding to those described in FIG.
[0022]
FIG. 1 is a longitudinal sectional view showing a schematic configuration of Reference Example 1 of the sputtering apparatus according to the present invention. In Reference Example 1, a plurality of wafers 11a, 11b, and 11c are placed in a vacuum vessel 51 and plasma is continuously applied. This is an example of a sputtering apparatus that performs processing to sequentially deposit an insulator, particularly a high-ferroelectric material, on the wafers 11a, 11b, and 11c.
[0023]
In FIG. 1, a target 52 (a target formed of an element constituting a desired insulating film as a target, or a reactive gas can be reacted with a reactive gas to form a desired insulator below the vacuum vessel 51. An electrode 53 on which a material is preferable) is placed, and a table 12 that is a movable wafer holder on which a plurality of wafers 11a, 11b, and 11c can be arranged and placed on the upper portion of the vacuum vessel 51. When the film formation on the processing target wafer 11a immediately above the target 52 is completed, the table 12 moves and the film formation on the next wafer 11b is performed.
[0024]
The protection plates 13a and 13b made of double metal cylinders are provided so as to surround the target 52, and the first protection plate 13a installed on the inner side has a floating potential and is installed on the outer side. The formed second deposition preventing plate 13b is at ground potential. The distance between the two protection plates 13a and 13b increases toward the top of the both protection plates 13a and 13b, and the neutrality of the charge is broken between the sheath thickness at the top and the plasma generated. , The distance of the layer region where the electric field is generated).
[0025]
In the vacuum vessel 51, only an inert gas (the inert gas includes He, Ne, Ar, Kr, Xe, Rn, but preferably Ar), or an inert gas and a reactive gas (reactive gas). frequency between the O _2, N ₂ there are such, O ₂ if the deposited substance to be an oxide, also N ₂ is preferable if nitride), or by introducing only the reactive gas, the electrode 53 and the vacuum vessel 51 Apply power (or DC power if the target is conductive). Then, plasma is generated immediately above the target 52, and film formation of the insulator is started.
[0026]
As the film formation progresses, an insulating film adheres to the first deposition plate 13a and the wafer 11a to be processed, and the ground plane cannot be seen, and the plasma spreads outside from the gap between the table 12 and the deposition plates 13a and 13b. I will try. However, the inner surface of the second deposition preventive plate 13b is a ground potential surface to which an insulator is difficult to adhere, and discharge occurs between them, so that the plasma spreads outside the dual construction preventive plates 13a and 13b. There is no.
[0027]
As described above, plasma does not spread outside the double-layer deposition preventing plates 13a and 13b, and stable plasma processing can be performed, and plasma does not hit the wafers 11b and 11c other than the wafer 11a to be processed. Plasma treatment could be performed.
[0028]
FIG. 2 is a longitudinal sectional view showing a schematic configuration of Reference Example 2 of the sputtering apparatus according to the present invention. Reference Example 2 is a sputtering apparatus that performs plasma processing in the same manner as Reference Example 1, and the configuration of Reference Example 1 is shown in FIG. The difference is that the double-layer deposition preventing plates 21a and 21b are both at ground potential. By adopting such a configuration, it is possible to prevent abnormal discharge from occurring between the two deposition preventing plates 21a and 21b.
[0029]
As described above, in Reference Example 2, as in Reference Example 1, plasma does not spread outside the double-layer deposition preventing plates 21a and 21b, stable plasma processing can be performed, and the processed wafer 11a. Plasma processing could be performed without plasma hitting the other wafers 11b and 11c. Furthermore, plasma treatment could be performed without causing discharge between the two protection plates 21a and 21b.
[0030]
FIG. 3 is a longitudinal sectional view showing a schematic configuration of Reference Example 3 of the sputtering apparatus according to the present invention. Reference Example 3 is a sputtering apparatus that performs plasma processing in the same manner as Reference Examples 1 and 2, and Reference Example 1 , 2 is a configuration in which the inner surface 32 of the first adhesion preventing plate 31a in the adhesion preventing plates 31a, 31b having a double structure is covered with an insulator 33. In this way, by forming the insulator 33 on the inner surface 32 of the first deposition preventing plate 31a, the insulator gradually attaches after the start of film formation until the grounding surface becomes invisible. Meanwhile, the plasma state can be prevented from changing over time.
[0031]
As described above, in Reference Example 3, in addition to the effects in Reference Examples 1 and 2, it was possible to perform stable plasma processing without the plasma state changing over time.
[0032]
FIG. 4 is a longitudinal sectional view showing a schematic configuration of a sputtering apparatus for explaining an embodiment of the present invention. This embodiment is a sputtering apparatus for performing plasma processing in the same manner as in Reference Examples 1 to 3, and The difference from the configurations of Examples 1 to 3 is that the first deposition plate 41a and the second deposition plate 41b in the duplex construction deposition plates 41a and 41b are electrically insulated, and the second deposition is performed. The plate 41b has a ground potential, and the first deposition plate 41a has a DC negative potential. By adopting this configuration, a sputtering phenomenon also occurs in the first deposition preventing plate 41a, whereby the insulator once attached to the inner surface 32 of the first deposition preventing plate 41a is removed.
[0033]
As described above, in the present embodiment, the maintenance cycle can be extended by reducing the adhesion speed of the insulator on the inner surface 32 of the first deposition preventing plate 41a.
[0034]
【The invention's effect】
As described above, in the sputtering apparatus according to the present invention, the adhesion preventing plates are doubled with a metal material and are not in contact with each other, the outer adhesion preventing plate is set to the ground potential, and the inner adhesion preventing plate is By setting the negative DC potential and the distance between the facing surfaces of the inner and outer protective plates different from each other, it is possible to prevent the plasma from spreading out of the protective plate and to stably perform plasma processing. It can be performed. Further, it is possible to prevent wafers other than the wafer to be processed from being exposed to plasma. In addition, the plasma treatment can be performed while removing the adhered insulator by setting the outer adhesion plate to the ground potential and the inner adhesion plate to the DC negative potential, thereby extending the maintenance cycle of the adhesion plate. be able to.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a schematic configuration of Reference Example 1 of a sputtering apparatus according to the present invention. FIG. 2 is a longitudinal sectional view showing a schematic configuration of Reference Example 2 of a sputtering apparatus according to the present invention. FIG. 4 is a longitudinal sectional view showing a schematic configuration of a sputtering apparatus for explaining an embodiment of the present invention. FIG. 5 is a schematic view of a conventional sputtering apparatus. Longitudinal sectional view showing configuration 【Explanation of symbols】
11a, 11b, 11c, 55 Wafer 12 Tables 13a, 21a, 31a, 41a First deposition plate 13b, 21b, 31b, 41b Second deposition plate 32 Inner surface 33 of first deposition plate Insulator 51 Vacuum Container 52 Target 53 Electrode 56 High frequency power supply

Claims (4)

A vacuum vessel capable of maintaining a vacuum, a wafer holder in the vacuum vessel on which a wafer to be processed by plasma is placed, and a power source that applies power to an electrode disposed facing the wafer holder And a deposition apparatus comprising a deposition plate disposed so as to surround the electrodes, the deposition plates are placed in a non-contact state with a metal material doubly, and the outer deposition plate is grounded. The sputtering apparatus is characterized in that the inner protection plate is set to a negative DC potential and the distance between the opposing surfaces of the inner and outer protection plates is different. The sputtering apparatus according to claim 1 , wherein an inner surface of the inner deposition preventing plate is covered with an insulator in the double deposition preventing plate . The sputtering apparatus according to claim 1 or 2, wherein the plasma treatment is a sputtering treatment for forming a dielectric thin film or a ferroelectric thin film . A plurality of wafers are mounted, a sputtering apparatus according to claim 1, 2 or 3, wherein further comprising a moving means for continuously processed by sequentially moving the wafer to the processing position.

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