JP3808653B2 - Method and apparatus for smoothing deposited film surface - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for smoothing a deposited film surface when forming a deposited film on the surface of an object by ion sputtering or the like.
[0002]
[Background Art and Problems to be Solved by the Invention]
In general, in the vapor deposition process, the material of the vapor deposition film is opposed to an object for forming the vapor deposition film in a vacuum, and the material of the vapor deposition film is irradiated with an electron beam or an ion beam to scatter atoms and molecular particles of the material, The deposited film is formed by attaching these particles to the surface of the object.
[0003]
By the way, the formation of a vapor deposition film is not a phenomenon in which the film surface of a thin film unit is uniformly attached to the surface of the target object. During the vapor deposition, molecular particles randomly adhere to the surface of the target object. Eventually, these cover the entire surface, and the film surface (surface) of the deposited film is formed on the surface of the object.
[0004]
That is, the process of generating a film surface by vapor deposition generally proceeds according to any of the three modes shown in FIGS. 6A to 6C, and the process is such that the thin film surfaces are uniformly stacked. Rather than being generated, atomic or molecular particles randomly adhere to the surface of the object, and these particles cover the surface of the object to generate a film surface.
[0005]
In the first mold shown in FIG. 6A, a cluster (a small lump of vapor-deposited film material particles) 1 first adheres to the surface of an object 2 and is connected to form a film surface. It is called a “Volmer-Weber” type. This type is most common when the atomic force between atoms on the deposited film side is stronger than the atomic force between the constituent atoms of the object and the atoms of the film.
[0006]
In the second type shown in FIG. 6B, a monoatomic layer 3 is formed on the surface of the object 2, and when this is completed, a monoatomic layer is formed on the monolayer 3 as a result, and a film grows as a result. , Called the Frank-van der Merwe type. It is understood that this type is obtained when the atomic force between the atom of the object and the vapor deposition atom is comparable to the atomic force between the vapor deposition atoms.
[0007]
The third type shown in FIG. 6 (c) is a film in which a monoatomic layer 3 film is first formed, and then a cluster 1 is deposited on the film, which are connected to form a film. It is called the Stransky-Krastanov type. This type is considered when the atomic force between the target atom and the vapor deposition atom is extremely strong.
[0008]
Accordingly, the film surface is never uniform in observation of the length unit at the molecular level, and is formed with fine irregularities. Observation of this state is possible with an atomic force microscope (AFM) or the like that allows observation of length units at the molecular level. However, the process of vapor deposition changes depending on factors such as the shape of the object surface, temperature, etc., and it has been difficult to say in the past how these molds are progressing.
[0009]
On the other hand, the film surface produced by vapor deposition or the like is widely used in the industry not only in the semiconductor industry but also in optical technology and tool technology. In this regard, for example, when measuring the tip diameter of a tool edge as an example, when observing the shape with a scanning electron microscope (SEM), a diamond tool or the like is highly insulating, and a gold vapor deposition film may be formed on the tool surface. Necessary. Therefore, it is necessary for the purpose to achieve the purpose that the deposited film should be flat with the minimum necessary thickness.
[0010]
Therefore, in the past, during the practical use of such vapor deposition and use in measurement samples, etc., the vapor deposition process was carried out in an environment where the physicochemical, thermal and electrical conditions were mainly adjusted and the object was fixed and stationary. However, with such conventional methods, it is extremely difficult to improve the function of film formation by smoothing the film surface or to optimize the formation of the deposited film by controlling the film surface formation rate. there were.
[0011]
[Means for solving the problems and their functions and effects]
SUMMARY OF THE INVENTION An object of the present invention is to provide a method and apparatus for smoothing a deposited film surface that advantageously solves the above-mentioned problems. When forming the deposited film, the object is subjected to vibration in a direction parallel to the surface of the object by the object exciting unit during the process of forming the deposited film.
[0012]
According to the experiment of the present inventor, when the vibration in the direction parallel to the surface of the object is applied to the object in the formation process of the deposited film as described above, it is clearly compared with the case where the vibration is not applied. Clusters (small lumps of vapor-deposited film material particles) were reduced, and as a result, the fine surface roughness of the film surface became fine, and a vapor-deposited film with a smoothed film surface was obtained. And, as mentioned above, when the vibration is applied to the target in the direction parallel to the surface of the target in the process of forming the deposited film, the generation speed of the film surface is obviously slow compared with the case where the vibration is not applied. Thus, it has been found that the formation rate of the film surface can be controlled to optimize the formation of the deposited film.
[0013]
Further, the vapor deposition film surface smoothing device of the present invention includes a vapor deposition film forming unit for forming a vapor deposition film of material particles on the surface of the object, and a vapor deposition film on the surface of the object by the vapor deposition film forming unit. An object excitation unit that applies vibration to the object in a direction parallel to the surface of the object during generation of the object.
[0014]
According to such an apparatus, vibration can be applied to the object in a direction parallel to the surface of the object in the process of forming the vapor deposition film. ) Can be made small, the surface roughness of the film surface can be made finer, and a vapor deposition film with a smoothed film surface can be obtained. can do.
[0015]
The object exciting unit in the apparatus of the present invention includes a piezoelectric element coupled to the object so that the object can be excited in a direction parallel to the surface of the object, and the piezoelectric element. And an oscillator that vibrates the piezoelectric element by supplying an electric signal to the piezoelectric element. If such a piezoelectric element and an oscillator are used, the excitation unit can be easily housed in a vacuum vessel. It can be configured to be as compact and operable in a vacuum as possible and not to have an electrical impact on the deposition process.
[0016]
Further, the vapor deposition film forming unit in the apparatus of the present invention may have an ion sputtering apparatus, and if such an ion sputtering apparatus is used, the vapor deposition film is easily formed on the object at a relatively low temperature. be able to.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Here, FIG. 1A is a vapor deposition film forming section in one embodiment of the vapor deposition film surface smoothing apparatus of the present invention for carrying out one embodiment of the vapor deposition film surface smoothing method of the present invention. FIG. 1B is a schematic diagram showing a schematic configuration of the ion sputtering apparatus in the apparatus of the above embodiment, and FIG. 2 is a schematic diagram of the above embodiment. It is a block diagram which shows schematic structure of the target object excitation part in an apparatus.
[0018]
Ion sputtering is characterized by its ability to be easily deposited at a relatively low temperature and is widely used. In the apparatus of the above embodiment, as shown in FIG. 1 (b), the inside of the container 4 of the ion sputtering apparatus is almost evacuated by a vacuum pump (not shown), and an anode 5 having an object 2 for forming a deposited film, When a DC voltage is applied between the cathode 6 having the target 6a by the power source 7, a glow discharge occurs between the electrodes 5 and 6, and the gas between them is ionized into cations and electrons to generate plasma. 8 state is obtained. In addition, although argon gas may be used as said gas, the residual gas of air is used in the apparatus of this Example.
[0019]
As shown in FIG. 1A, the cations in the plasma 8 are attracted to the cathode 6 side and collide with the target 6a made of the deposited film material on the cathode 6 side. Atoms are ejected. This is a phenomenon called sputtering, in which the atoms of the ejected material continue to fly, and some of them collide with the surface of the object 5a on the anode 5 side and adhere thereto. In the apparatus of this embodiment, gold (Au) is used for the target 6a, and a thin piece of a silicon (Si) substrate generally used as a semiconductor substrate is used for the object 2 .
[0020]
In the apparatus of the above embodiment, although not shown in FIG. 1, the object vibration unit 9 shown in FIG. 2 is provided in the container 4, and this object vibration unit 9 is provided on the anode 5. The laminated piezoelectric element 9a having one end fixed to the container 4 side and the other end bonded and fixed to the object 2 with an adhesive, and also disposed in the container 4 and attached to the piezoelectric element 9a An oscillator 9b for supplying an alternating voltage (specifically, a small function generator circuit board that operates with a storage battery), and an oscillograph 9c disposed outside the container 4 for confirming the output frequency and output waveform of the oscillator 9b. And have. The oscillator 9b here can output an AC voltage having a maximum output (pp value) of 2 V to an arbitrary frequency between 100 Hz and 300 kHz to the piezoelectric element 9a, and the piezoelectric element driven by the AC voltage. The piezoelectric element 9a expands and contracts in the longitudinal direction, and the object 2 placed on the anode 5 side can be vibrated in the horizontal direction in FIG.
[0021]
The method of the above embodiment applies vibration during the generation of the film surface of the vapor deposition material on the object 2 using the apparatus of the embodiment, and the inventor of the present application performs the film surface generation process in the method. In order to observe, a large number of substrate strips (10 mm square) as the object 2 were prepared, and deposition was performed for each substrate strip for 5 seconds, 10 seconds, 20 seconds, and 60 seconds. The surface state of the substrate strip was observed with an atomic force microscope (AFM). At that time, in order to clarify the influence of vibration, the case where vibration was not applied to the substrate strip for the same deposition time and the case where vibration was applied were compared. Further, it was confirmed that the substrate strip can be separated from the state bonded to the piezoelectric element 9a by using an adhesive melting agent.
[0022]
FIG. 3A shows an image observed by AFM of the surface of the substrate strip when the apparatus is vapor-deposited for 20 seconds without applying vibration by the apparatus of the above embodiment, and FIG. 3B is a view of the above embodiment by the apparatus of the above embodiment. This is an image observed by AFM of the surface of the substrate strip when it is deposited for 20 seconds while oscillating at 100 kHz by the above method, and the magnification is 100,000 times. The diameters of unit shapes (clusters) that are characteristically observed in these images (the major axis in the case of an elliptical shape), the ten-point average roughness Rz of the fine surface, respectively, on the vertical axis, and the deposition time on the horizontal axis, The graphs of FIGS. 4 and 5 show the state of the film surface obtained by the above vapor deposition using the excitation frequency as a parameter.
[0023]
As shown in these graphs, when vibration is applied to the substrate strip during the film surface generation process of the vapor deposition material on the surface of the substrate strip as the object 2 by the apparatus of the above embodiment, In particular, at the initial stage of deposition from the start of deposition to 20 seconds, the cluster diameter is clearly smaller than when no vibration is applied, and as a result, the value of the fine surface roughness is reduced, and the frequency selectivity is reduced. The higher the frequency, the smaller the diameter of the cluster and the smaller the value of the fine surface roughness. Especially in the case of 10 kHz, the cluster is small, and the fine surface roughness becomes small. A smooth film surface shape was obtained, and the effect of applying vibration was confirmed.
[0024]
Since the natural frequency of the piezoelectric element 9a in the apparatus of the above embodiment is in the vicinity of slightly exceeding 7 kHz, the amplitude of the substrate strip is larger at 10 kHz than at other frequencies. As a result, it is estimated that the larger the amplitude of the object, the smaller the cluster diameter and the smaller the value of the fine surface roughness.
[0025]
Furthermore, in the graph of FIG. 4, the diameter of the cluster is smaller at the time of vibration than at the time of non-vibration, and the diameter of the cluster is smaller as the vibration frequency is higher. It was confirmed that the higher the excitation frequency, the slower the film surface generation rate. Therefore, according to the method and apparatus of the above embodiment, it is possible to optimize the formation of the deposited film by controlling the film surface generation rate.
[0026]
As mentioned above, although demonstrated based on the example of illustration, this invention is not limited to the above-mentioned example, For example, an electron beam sputtering device may be used for a vapor deposition film formation part instead of an ion sputtering device, Instead of the piezoelectric element, the object excitation unit may be another vibration means, for example, a vibration source that transmits vibration to the object from outside the sputtering container via the transmission member.
[0027]
Further, the method of coupling between the vibration means such as a piezoelectric element and the object may be another method such as clamping instead of bonding with an adhesive, and the vapor deposition material and the object may be made of the above materials. However, the present invention is not limited to this, and may be changed as appropriate.
[Brief description of the drawings]
FIG. 1 (a) shows an ion as a deposition film forming unit in one embodiment of the deposition film surface smoothing apparatus of the present invention for carrying out one embodiment of the deposition film surface smoothing method of the present invention; Explanatory drawing which shows typically the vapor deposition process by a sputtering device, (b) is a block diagram which shows schematic structure of the ion sputtering device in the apparatus of the Example.
FIG. 2 is a configuration diagram showing a schematic configuration of an object excitation unit in the apparatus of the embodiment.
FIG. 3A is an observation image by AFM of the surface of a substrate strip when it is deposited for 20 seconds without applying vibration by the apparatus of the above embodiment, and FIG. 3B is a view of the above embodiment by the apparatus of the above embodiment. It is the observation image by AFM of the board | substrate strip surface at the time of vapor-depositing for 20 seconds, vibrating at 100 kHz by the method of.
FIG. 4 is a graph showing the cluster diameter of the film surface by vapor deposition by the method of the above embodiment in relation to the vapor deposition time and the excitation frequency.
FIG. 5 is a graph showing the fine surface roughness of the film surface by vapor deposition according to the method of the above embodiment in relation to the vapor deposition time and the excitation frequency.
FIGS. 6A to 6C are explanatory views showing three types of film surface generation processes by vapor deposition.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Cluster 2 Object 3 Monoatomic layer 4 Container 5 Anode 6 Cathode 6a Target 7 Power supply 8 Plasma 9 Object excitation part 9a Laminated piezoelectric element 9b Oscillator 9c Oscillograph

Claims (4)

When forming a vapor deposition film on the surface of an object, the object is subjected to vibration in a direction parallel to the surface of the object by the object vibration unit during the process of forming the vapor deposition film. The method of smoothing the surface of the deposited film. A vapor deposition film forming section for forming a vapor deposition film of material particles on the surface of the object;
An object excitation unit that applies vibration in a direction parallel to the surface of the object to the object during the generation of a vapor deposition film on the surface of the object by the vapor deposition film forming unit;
An apparatus for smoothing a deposited film surface.   The object vibration unit supplies a piezoelectric signal to the piezoelectric element coupled to the object so as to vibrate the object in a direction parallel to the surface of the object, and an electric signal to the piezoelectric element. An apparatus for smoothing a deposited film surface according to claim 2, further comprising: an oscillator that vibrates the piezoelectric element.   The said vapor deposition film formation part is a smoothing apparatus of the vapor deposition film surface of Claim 2 or Claim 3 which has an ion sputtering device.

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