JP5971723B2 - Plasma processing apparatus and plasma processing apparatus protective plate - Google Patents

Description

  The present invention relates to a plasma processing apparatus for forming a thin film which is an electrically insulating material on a substrate by plasma in a processing chamber, and a deposition plate used therefor.

  A plasma processing apparatus for forming a thin film which is an electrically insulating material on a substrate has a processing chamber, the substrate is disposed in the processing chamber, and a plasma gas and a reactive gas are introduced into the processing chamber to perform plasma processing. I do. By this plasma treatment, sputtered particles and gas components constituting the thin film are generated in the treatment chamber. Sputtered particles and gas components are deposited on a substrate disposed in the processing chamber or react with the substrate to form an insulating thin film on the substrate.

However, if film formation is continued, film formation particles adhere and deposit inside the processing chamber other than the surface of the substrate, so in conventional devices, a deposition plate is placed in the processing chamber to form a film on the processing chamber wall. Some have been proposed to prevent particles from accumulating. In an apparatus using the processing chamber wall as an anode, the deposition preventing plate is given a function as an anode.
When deposited particles or the like are deposited on the surface of the deposition preventing plate, a portion where the deposited film is formed thick and a portion where the deposited film is relatively thin are generated, and the resistance is likely to increase unevenly. In particular, when the film-forming particles have an insulating property, a high-resistance portion where the deposited film is formed thick and a low-resistance portion where the deposited film is relatively thin are generated, and resistance non-uniformity becomes remarkable.
If the plasma treatment is continued in this state, the plasma discharge becomes unstable due to, for example, concentration of electrons at a low resistance, making it difficult to perform the plasma treatment stably.
This can be expressed in time series as follows.
1) A film is deposited on the deposition preventing plate (anode potential). The deposited film varies depending on the plasma distribution and the gas mass concentration, and is not laminated uniformly.
2) A potential difference is generated in the electric field (resistance in vacuum) by depositing the film non-uniformly.
3) The distribution of plasma changes due to the concentration of electrons in the low resistance portion.
4) If the phenomenon further proceeds, heat may be generated and eventually the deposition preventing plate itself may be destroyed.

As a technique for preventing the non-uniform resistance of the anode, for example, an apparatus described in Patent Document 1 has been proposed.
In this apparatus, a conductive anode is disposed between opposing targets, and the distance from the erosion region of the target to the anode is defined, thereby suppressing the passivation of the anode and maintaining the conductivity of the anode.

JP 2007-131930 A

  However, in the apparatus shown in Patent Document 1, the apparatus configuration is limited to a magnetron sputtering apparatus, and there are restrictions on the arrangement position of the target, the anode, etc. Unevenness cannot be prevented.

  The present invention has been made against the background of the above circumstances, and can be disposed at an appropriate position as an adhesion preventing plate without being restricted by the arrangement, and is stable by avoiding uneven resistance of the adhesion preventing plate. It is an object of the present invention to provide a plasma processing apparatus and a plasma processing apparatus deposition preventive plate that enable plasma discharge.

That is, among the plasma processing apparatuses of the present invention, the first aspect of the present invention is a plasma processing apparatus for forming a thin film on a substrate by plasma in a processing chamber.
A plurality of conductive adhesion-preventing plates that prevent an insulator from adhering to the substrate other than the substrate and function as an anode;
A power supply unit for applying a discharge voltage in the processing chamber,
At least a part of the adhesion-preventing plate is provided with a plurality of through-holes having a size of 1 to 5 mm, penetrating the plate surface from the front to the back, and the adhesion-preventing plates provided with the through-holes are 1 to each other. The through-hole provided in one side of the said adhesion prevention board arrange | positioned with a space | interval of -5 mm, the plate surface facing each other, and the other arrangement | positioning of the said adhesion prevention board, and the said through-hole provided in the other However, the adhesion preventing plates that are arranged so as not to be positioned along the direction with respect to the plasma generation side direction and that face the plate surfaces are electrically connected by a conductive connector having a cross-sectional area of 10 mm ² or less. The protective plate located on the processing chamber wall side is disposed along the processing chamber wall and is electrically connected to the processing chamber .

  The plasma processing apparatus of the second aspect of the present invention is characterized in that, in the first aspect of the present invention, the thin film is an electrically insulating material.

The plasma processing apparatus of the third aspect of the present invention is characterized in that, in the first or second aspect of the present invention , a target which is at least a part of the raw material of the thin film is disposed in the processing chamber.

A plasma processing apparatus according to a fourth aspect of the present invention is the plasma processing apparatus according to any one of the first to third aspects of the present invention, further comprising a source gas supply unit that supplies a source gas that becomes at least a part of the source of the thin film into the processing chamber It is characterized by providing.

The adhesion-preventing plate of the fifth aspect of the present invention is a plurality of conductive adhesion-preventing plates that are disposed in a plasma processing apparatus for forming a thin film on a substrate by plasma in a processing chamber and function as anodes,
A plurality of through-holes having a size of 1 to 5 mm penetrating the front and back of the plate surface are provided, and the plate surfaces are opposed to each other with an interval of 1 to 5 mm , and are arranged at intervals. The through hole provided on one side of the deposition plate and the through hole provided on the other side of the deposition plate are positioned so as not to be positioned along the direction with respect to the plasma generation side direction. The adhesion prevention plates facing each other are electrically connected by a conductive connector having a cross-sectional area of 10 mm ² or less, and the adhesion prevention plate located on the processing chamber inner wall side is disposed along the processing chamber wall and is It is characterized by being electrically connected to the processing chamber .

  According to the present invention, even if an insulating material adheres to the entire surface due to the through-hole of the deposition preventive plate, an electron passage space is ensured, and electrons can reach the opposing deposition preventive plate and the processing chamber wall, Electron movement is not blocked by the landing plate.

  Specific examples of the plasma processing apparatus of the present invention include a reactive sputtering apparatus and a plasma CVD apparatus, but are not limited thereto. Examples of the thin film that can be formed include an oxide film and a nitride film. Specifically, a silicon oxide film, a silicon nitride film, a titanium nitride film, and the like can be shown. The present invention is particularly suitable for the formation of an electrically insulating thin film.

  The power supply unit applies a discharge voltage in the processing chamber, and can generate plasma in the processing chamber by applying the discharge voltage. As the power supply unit, DC voltage, AC voltage, pulse voltage or the like can be used, and is not limited to a specific one.

  In the processing chamber, a target that is at least a part of the raw material of the thin film can be installed to perform plasma processing, and a source gas supply unit that supplies source gas to the processing chamber can be provided. A thin film material may be obtained only by source gas without using a target, or a thin film material may be obtained by reaction with a substrate.

In addition, the deposition preventing plate disposed in the plasma processing apparatus has conductivity and functions as an anode. The deposition preventing plate can be electrically connected to the processing chamber.
Furthermore, at least some of the deposition plates have through holes penetrating the front and back, and are arranged with the plate surfaces facing each other with a space therebetween.

The cross-sectional shape and size of the through hole are not particularly limited, but may be a circular shape or a polygonal shape. The size of the through hole is desirably 1 to 5 mm. In the irregular shape, for example, both the minimum size and the maximum size are within 1 to 5 mm. That is, the through hole can have a size that fits between a circle with a diameter of 1 mm and a circle with a diameter of 5 mm.
If the size of the through hole is less than 1 mm, the passage of electrons is hindered, and the discharge becomes unstable easily. Also, if the size of the through hole exceeds 5 mm, the film-forming particles that have passed through the first through-hole adhere to and deposit on a large area of the second adhesion-preventing plate, impairing the electron permeability, Causes unstable discharge.
The through holes can be formed over the entire surface of the plate or distributed over a part of the surface. For example, the through holes can be arranged at a predetermined interval. As a space | interval of holes, 1-5 mm can be mentioned as distance between the peripheries of a hole, for example.
If it is less than 1 mm, the area of the through hole becomes too small and the plasma discharge becomes unstable, and if it exceeds 5 mm, the effect of the through hole is small and the plasma discharge becomes unstable.
Note that it is desirable that the size of the through holes and the interval between the through holes be the same.

Although the mutual space | interval at the time of making the adhesion prevention plates which have a through-hole oppose is not specifically limited, For example, it can be set as the space | interval of 1-5 mm.
If the distance is less than 1 mm, the electrons reach only the deposited particles due to the straightness of the electrons that have passed through the through-holes of the first deposition plate, and the current flow is inhibited and the discharge stability is reduced. Difficult to get.
On the other hand, when the distance exceeds 5 mm, the deposited particles passing through the first through-hole adhere to and deposit on a large area of the second adhesion-preventing plate, impair the electron permeability, and cause unstable discharge. Invite

In addition, it is desirable that the adhesion prevention plates arranged opposite to each other are connected to each other by a connection tool made of a conductive screw or the like. Thereby, an electric current flows gradually through a connection tool, and there exists an electric current distribution effect and a time difference conduction effect. For this reason, it is desirable that the connecting tool is not connected to the surface, but distributes screws or the like for point connection on a small surface (for example, 10 mm ² or less) on the surface.

  Moreover, in the adhesion prevention board arrange | positioned opposingly, it is desirable for the through-hole provided in one and the through-hole provided in the other to not have both through-holes along this direction with respect to the plasma generation side direction. If both through-holes are along this direction, the film-forming particles that have passed through the first through-hole reach the processing chamber wall directly through the second through-hole, This is because the function is impaired.

  As described above, according to the present invention, stable plasma discharge can be realized without restricting member arrangement, and stable plasma treatment can be performed over a long period of time.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1, showing an embodiment of the present invention, is a schematic view showing a plasma processing apparatus when a hole plate is arranged. Similarly, it is the schematic which shows the adhesion prevention board used for a plasma processing apparatus. It is the schematic which shows the plasma processing apparatus of one Embodiment of this invention.

Hereinafter, a plasma processing apparatus and a plasma processing apparatus protective plate according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2.
The plasma processing apparatus 1 includes a processing chamber 2, and the processing chamber 2 has an airtight structure that can be evacuated and is electrically grounded. The processing chamber is not particularly limited as long as it has a structure in which plasma can be generated and a thin film can be formed on the substrate. For example, the processing chamber can be decompressed to a vacuum state of about 0.1 to 10 Pa. It can be of an airtight structure.

A vacuum pump 3 for evacuating the processing chamber 2 is connected to the processing chamber 2, and a gas introduction line 4 for introducing gas into the processing chamber 2 is connected. The gas introduction line 4 can introduce, for example, a sputtering gas such as an argon gas, or a reactive gas such as an oxygen gas or a nitrogen gas, or a gas can be selectively introduced. The gas introduction line 4 corresponds to the raw material gas supply unit of the present invention.
Note that a line for introducing a sputtering gas into the processing chamber 2 and a line for introducing a reactive gas into the processing chamber 2 may be connected to the processing chamber 2 independently.
The processing chamber 2 is connected to an exhaust line 5 for exhausting the gas in the processing chamber 2.
In the present invention, a reactive gas may not be used. For example, Ar used for sputtering may be used.

  The top plate in the processing chamber 2 is provided with a substrate holder 6 that holds the substrate 20 on the lower surface side, and the substrate holder 6 is grounded. The type of the substrate 20 is not particularly limited, and examples thereof include a semiconductor substrate such as a silicon substrate, a glass substrate, and the like.

A target support 7 is attached to the bottom of the processing chamber 2 in a state of being insulated from the processing chamber 2, and a target 21 is installed on the target support 7. An appropriate material can be selected for the target 21 in accordance with the type of thin film to be formed, such as a silicon target for forming a silicon oxide film, a silicon nitride film, a titanium target for forming a titanium nitride film, and the like. It can be illustrated. A target made of a metal material or an insulating material can be used as the target.
The target support 7 is electrically connected to the negative electrode of a DC power supply 9 corresponding to the power supply unit of the present invention, and the positive electrode of the DC power supply 9 is grounded.

  In the processing chamber 2, two conductive adhesion-preventing plates 10 and 11 are spaced from each other so as to cover the side surface of the processing chamber between the target support 7 and the substrate holder 6 and the bottom surface of the processing chamber. It is installed with. The thickness of the deposition preventing plate is not particularly limited.

  As shown in FIGS. 1 and 2, the adhesion preventing plates 10 and 11 have circular through holes 12 and 13 that penetrate the front and back surfaces, respectively, and the through holes 12 and 13 are arranged vertically and horizontally. The through-holes have a diameter of 1 to 5 mm, and have an interval (distance between peripheral edges) of 1 to 5 mm. In addition, the adhesion prevention board may include what does not have a through-hole in part.

Of the deposition plates 10 and 11, the deposition plate 10 located on the processing chamber wall 2a side is disposed along the processing chamber wall 2a and is electrically connected to the processing chamber 2a.
Further, the deposition preventing plate 11 has a gap with the deposition preventing plate 10 and is disposed so that the plate surface faces the deposition preventing plate 10, and is electrically and mechanically connected to each other by a conductive bolt 15. Connected. The bolt 15 has a small cross-sectional area of 10 mm ² and electrically connects the adhesion preventing plates 10 and 11 by point contact. The space | interval of the adhesion prevention plates 10 and 11 is set by the connection of the volt | bolt 15, and the space | interval is 1-5 mm.

Further, the through holes 12 and 13 of the deposition preventing plates 10 and 11 are positioned so as not to be positioned along the direction with respect to the plasma generation side while being shifted from each other. The lower space directly under the substrate 20 can be seen as the plasma generation side.
FIGS. 1 and 2 show a configuration in which two of the adhesion prevention plates 10 and 11 are arranged to face each other, but three or more adhesion prevention plates are arranged at intervals. Also good.

Next, the operation of the plasma processing apparatus 1 will be described.
First, the substrate 20 is set on the substrate holder 6 on the lower surface side of the top plate in the processing chamber 2, and the target 21 is set on the target support 7.
Next, the inside of the processing chamber 2 is depressurized to a predetermined vacuum state, for example, 0.1 to 10 Pa by the vacuum pump 3. Next, a mixed gas of plasma gas such as argon gas and reactive gas such as oxygen gas and nitrogen gas is introduced into the processing chamber 2 through the gas introduction line 4 at a predetermined flow rate. Thereafter, a DC voltage is applied to the ground side by the DC power source 9. By applying this voltage, a discharge is generated between the substrate holder 6, the processing chamber wall 2 a, the deposition preventing plate 10 and the target support 7, and plasma by plasma gas is generated. The plasma generator 16 is mainly located on the lower side of the substrate holder 6. The plasma sputters the target 21 and excites the reactive gas to generate insulating film-forming particles. The generated film-forming particles form a thin film on the substrate 20 and a part of the film-formed particles are scattered in the processing chamber 2 and are also deposited on the deposition preventing plates 10 and 11.

In the deposition preventing plate 11, film forming particles adhere to the surface, and a part thereof passes through the through holes 13 of the deposition preventing plate 11 and reaches the surface of the deposition preventing plate 10. However, since the size of the through hole 13 is small, the passage of the film-forming particles is limited. Further, since the through-hole 13 of the deposition preventing plate 11 and the through-hole 12 of the deposition preventing plate 10 are not positioned linearly from the plasma generation source side, the film formation particles passing through the through-hole 13 are deposited on the deposition preventing plate. It deposits on the surface of the deposition preventing plate 10 without passing through the 10 through holes 12. Therefore, the state where the processing chamber inner wall 2a is exposed through the through hole 13 and the through hole 12 is maintained, the movement of electrons is ensured, and the conductivity is maintained.
Therefore, even when the formation of the thin film is continued, the conductivity with the processing chamber inner wall 2a is not lost even if the deposition preventing plates 10 and 11 are insulated, and the plasma discharge is stabilized.

In the above embodiment, the plasma processing apparatus using the target has been described. However, the present invention is not limited to this, and the source gas is converted into plasma by plasma discharge without using the target and insulated on the substrate. The present invention can also be applied to a plasma CVD apparatus for forming a physical thin film.
Hereinafter, the plasma CVD apparatus will be described in detail.

  FIG. 3 is a cross-sectional view showing a plasma processing apparatus 1a according to another embodiment. As illustrated, the plasma processing apparatus 1 a is a plasma CVD apparatus and includes a processing chamber 2. The processing chamber 2 has an airtight structure that can be depressurized in vacuum and is electrically grounded. In addition, the same code | symbol is attached | subjected and demonstrated about the structure similar to the said embodiment.

A vacuum pump 3 as a mechanism for evacuating the inside of the processing chamber 2 and an exhaust line 5 for exhausting the inside of the processing chamber 2 are connected to the processing chamber 2.
In addition, a gas introduction line 4 for introducing atmospheric gas into the processing chamber 2 is connected to the processing chamber 2. The gas introduction line 4 is configured to be able to introduce a source gas such as oxygen gas or nitrogen gas or a carrier gas such as argon gas.

A substrate holder 6 that holds a substrate 20 on which a thin film that is an electrical insulator is to be formed is provided on the lower surface side of the top plate in the processing chamber 2.
In the processing chamber 2, conductive adhesion-preventing plates 10 and 11 are installed so as to surround the periphery of the space between the electrode 22 and the substrate holder 6 except for the bottom and the top plate lower surface side.
The adhesion preventing plate 10 prevents an insulator constituting a thin film to be formed on the substrate 20 from adhering to other than the substrate 20. In particular, in the configuration shown in FIG. 3, the deposition preventing plates 10 and 11 are arranged so as to prevent the insulator from adhering to the inner wall surface 2 a of the processing chamber 2. The adhesion preventing plates 10 and 11 have the same structure as the plasma processing apparatus 1 of the above embodiment, and detailed description thereof is omitted here.

Next, the operation of the plasma processing apparatus 1a will be described.
First, the substrate 20 is attached on the substrate holder 6.
Next, the inside of the processing chamber 2 is depressurized to a predetermined vacuum state by the vacuum pump 3, and a plasma gas such as argon gas and a source gas such as oxygen gas and nitrogen gas are passed through the gas introducing line 4 into the processing chamber 2. The mixed gas with the carrier gas is introduced at a predetermined flow rate. Thereafter, a DC voltage is applied to the ground side by the DC power source 9. By applying this voltage, a discharge is generated between the electrode 22 and the substrate holder 6, the processing chamber inner wall 2a, and the deposition preventing plates 10 and 11, and plasma is generated by the plasma gas.

Due to the generation of plasma, electrons having energy of a certain level (ionization voltage) or higher collide with the source gas, and chemically active film-forming particles are generated.
The film-forming particles adhere and deposit on the surface of the substrate 20 to form a thin film, and also deposit and deposit on the deposition preventing plates 10 and 11.
However, as described in the above embodiment, the anti-adhesion plates 10 and 11 do not lose conductivity with the processing chamber walls even if the anti-adhesion plates 10 and 11 are insulated, and the plasma discharge is stabilized. The

  As mentioned above, although this invention was demonstrated based on the said embodiment, this invention is not limited to the content of the said embodiment, A suitable change is possible unless it deviates from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Plasma processing apparatus 2 Processing chamber 2a Inner wall surface 3 Vacuum pump 4 Gas introduction line 6 Substrate holder 7 Target support base 9 DC power supply 10 Depositing plate 11 Depositing plate 12 Through hole 13 Through hole 15 Fixing screw 16 Plasma generating part 20 Substrate 21 Target

Claims (5)

In a plasma processing apparatus for forming a thin film on a substrate by plasma in a processing chamber,
A plurality of conductive adhesion-preventing plates that prevent an insulator from adhering to the substrate other than the substrate and function as an anode;
A power supply unit for applying a discharge voltage in the processing chamber,
At least a part of the adhesion-preventing plate is provided with a plurality of through-holes having a size of 1 to 5 mm, penetrating the plate surface from the front to the back, and the adhesion-preventing plates provided with the through-holes are 1 to each other. The through-hole provided in one side of the said adhesion prevention board arrange | positioned with a space | interval of -5 mm, the plate surface facing each other, and the other arrangement | positioning of the said adhesion prevention board, and the said through-hole provided in the other However, the adhesion preventing plates that are arranged so as not to be positioned along the direction with respect to the plasma generation side direction and that face the plate surfaces are electrically connected by a conductive connector having a cross-sectional area of 10 mm ² or less. The plasma processing apparatus is characterized in that the deposition preventing plate located on the processing chamber wall side is disposed along the processing chamber wall and is electrically connected to the processing chamber .   The plasma processing apparatus according to claim 1, wherein the thin film is an electrically insulating material. The process chamber, the plasma processing apparatus according to claim 1 or 2, characterized in that at least a portion comprising a target of material for the thin film is placed. The plasma processing apparatus according to any one of claims 1 to 3, further comprising a source gas supply unit for supplying a raw material gas comprising at least a portion in the processing chamber of the material of the thin film. A plurality of conductive deposition plates disposed in a plasma processing apparatus for forming a thin film on a substrate by plasma in a processing chamber and functioning as an anode;
A plurality of through-holes having a size of 1 to 5 mm penetrating the front and back of the plate surface are provided, and the plate surfaces are opposed to each other with an interval of 1 to 5 mm , and are arranged at intervals. The through hole provided on one side of the deposition plate and the through hole provided on the other side of the deposition plate are positioned so as not to be positioned along the direction with respect to the plasma generation side direction. The adhesion prevention plates facing each other are electrically connected by a conductive connector having a cross-sectional area of 10 mm ² or less, and the adhesion prevention plate located on the processing chamber inner wall side is disposed along the processing chamber wall and is A plasma processing apparatus deposition-preventing plate, wherein the plasma processing apparatus protective plate is electrically connected to the processing chamber .

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