JP4734020B2 - Deposition equipment - Google Patents

Description

  The present invention relates to a film forming apparatus for forming a predetermined thin film on a processing substrate, and in particular, at least one of film formation by a sputtering method and film formation by a chemical film formation method is performed in the same vacuum chamber. The present invention relates to a film forming apparatus.

In recent years, along with higher integration and higher speed of LSIs, semiconductor elements have been miniaturized and multilayered, and accordingly, embedded wiring structures have been used. As a wiring material embedded in an interlayer connection hole such as a via hole or a trench formed in an insulating film, it is a mainstream to use copper having a small specific resistance value. Here, it is known that copper in the embedded wiring has a property of being easily diffused into an insulating film such as SiO ₂ unlike other wiring materials such as aluminum.

  In this case, in order to prevent insulation failure caused by diffusion into the insulating film, for example, between the insulating film and the copper thin film for wiring formation (inner surface of the interlayer connection hole), by CVD method or sputtering method, By interposing a conductive thin film (barrier film), it is considered that the copper thin film and the insulating film are prevented from coming into direct contact to suppress or prevent diffusion into the insulating film.

Examples of the film formation method for the barrier film include a chemical film formation method, for example, an ALD method. In this ALD method, after raising the temperature of a processing substrate installed in a vacuum chamber to a predetermined temperature, a source gas and a reaction are performed. By repeating either the step of introducing one of the gases and adsorbing it on the processing substrate, and the step of once evacuating the introduced gas and then introducing the other and reacting on the processing substrate, the atomic layer is reduced to about A metal layer is laminated to obtain a barrier film having a predetermined thickness (Patent Document 1).
Japanese Patent Laid-Open No. 11-54459 (for example, see the description of claim 1)

  When a barrier film is formed by this ALD method, there is a problem that sufficient adhesion strength to an interlayer insulating film or the like cannot be obtained. From this, it is conceivable to form an adhesion layer of the barrier film by sputtering, for example, prior to formation of the barrier film by ALD. In this case, if the formation of the barrier film by the ALD method and the formation of the adhesion layer by the sputtering method are performed in separate vacuum chambers, problems such as a reduction in the working efficiency of the barrier film formation occur. Therefore, it is required to form a barrier film by an ALD method and an adhesion layer by a sputtering method.

  When thin film formation by ALD method and thin film formation by sputtering method can be performed in the same vacuum chamber, the gas introduced during film formation by ALD method is adsorbed on the surface of sputtering target. There is a risk of contamination. If the target is contaminated, a problem such as inducing abnormal discharge occurs at the time of film formation by sputtering, and good film formation cannot be performed.

  Therefore, in view of the above points, an object of the present invention is to perform film formation by chemical film formation and film formation by sputtering in a single vacuum chamber while preventing target contamination. To provide an apparatus.

In order to solve the above-described problems, a film forming apparatus according to the present invention has a substrate stage in which a processing substrate can be placed in a vacuum chamber, and has a target provided to face the substrate stage. This vacuum chamber has a sputtering film forming means capable of forming a film by a sputtering method and a chemical film forming means having a gas introducing means and capable of forming a film by a chemical film forming method on a processing substrate. Is a film forming apparatus provided with a partition plate that partitions the first space where the target exists and the second space where the substrate stage exists, the target being capable of changing the horizontal position of the target. is attached to, in any moved position, by generating plasma in the first space is capable of sputtering of the target, the position of any by said moving means When you move the target, characterized in that the opening facing this target to be performed by a sputtering method to process a substrate formed in the partition plate.

  According to the present invention, after the target is moved to a position coinciding with the opening formed in the partition plate by the moving means, the sputtering film forming means is operated to form a predetermined thin film on the processing substrate by the sputtering method. The Next, the target is moved to a position where the opening and the target do not coincide with each other, and in this state, the chemical film forming means is operated to form a predetermined thin film on the processing substrate by the chemical film forming method. In this case, since the target is shielded by the partition plate, the flow of the raw material gas and the reaction gas introduced when performing the chemical film-forming method into the vicinity of the target is suppressed, and this is caused by gas adsorption. Target contamination can be prevented.

  In the chemical film-forming method, the process of introducing the source gas to adsorb the source gas on the surface of the processing substrate and the process of introducing the reaction gas and reacting with the adsorbed source gas are periodically repeated. The ALD method is preferred.

  In addition, if the substrate stage is provided with a driving means for rotating the processing substrate placed on the substrate stage, the in-plane uniformity of the film thickness is high when a predetermined thin film is formed on the processing substrate by the sputtering method. You can hold it.

By the way, when the substrate stage and the target are arranged to face each other, it is necessary to reduce the volume of the second space in which the chemical film forming method is performed in order to increase the film forming speed when forming the thin film by the chemical film forming method. There is. In this case, the moving means is a disk provided in the first space, and the rotation axis of the driving means for rotating the disk is shifted from the rotation center of the driving means for rotating the processing substrate. It should be provided.

The gas introducing means has a ring-shaped head portion provided above the substrate stage so as to surround the substrate stage, and a predetermined gas is jetted toward the processing substrate on the head portion. If a plurality of gas introduction holes are formed at a predetermined interval, it may be possible to uniformly supply a predetermined gas to the processing substrate.

  In addition, if a gas introduction means that enables introduction of a predetermined purge gas is provided in the vicinity of the target, gas flow into the vicinity of the target can be further suppressed during film formation by a chemical film formation method. Good.

  Furthermore, if the target is shielded by the partition plate and controlled to operate the sputtering film forming means to perform pre-sputtering, even if the target surface is somewhat contaminated by the gas flowing into the vicinity of the target, A portion contaminated by the pre-sputtering can be cleaned, and it is possible to prevent the occurrence of problems such as inducing abnormal discharge during film formation by the sputtering method, thereby enabling good film formation.

  As described above, the film forming apparatus of the present invention can perform the film formation by the chemical film formation method and the film formation by the sputtering method in the same vacuum chamber while preventing contamination of the target. There is an effect.

  Referring to FIGS. 1 to 3, reference numeral 1 denotes a film forming apparatus according to the present invention which can satisfactorily perform film formation by an ALD method which is a chemical film formation method and film formation by a sputtering method in the same vacuum chamber. is there. The film forming apparatus 1 has a cylindrical vacuum chamber 11 having a vacuum exhaust means 2 such as a turbo molecular pump, and a substrate on which a processing substrate S such as a silicon wafer can be placed at the bottom of the vacuum chamber 11. A stage 12 is provided. In order to heat the processing substrate S to a predetermined temperature, the substrate stage 12 incorporates, for example, a known heating means (not shown) of a resistance heating method.

  Also, first and second gases that are introduced into the vacuum chamber 11 located immediately above the substrate stage 12 when a film is formed on the processing substrate S by a chemical film forming method are introduced. Introducing means 31 and 32 are provided, and the heating means and the gas introducing means 31 and 32 constitute the chemical film forming means 3. As shown in FIGS. 1 and 2, the first and second gas introduction means 31 and 32 are concentric so as to surround the substrate stage 12, and are provided with ring-shaped head portions 31 a that are shifted in the vertical direction. Each of the bed portions 31a and 32a is formed with four gas introduction holes 31b and 32b at different angles by 90 degrees so that a predetermined gas is ejected toward the processing substrate S. . Moreover, each head part 31a, 32a is each connected to the predetermined gas source (For example, source gas source, reaction gas source) which is not shown in figure via the gas pipe | tubes 31c and 32c which interposed the mass flow controller.

  For example, when a barrier film is formed by an ALD method in an interlayer connection hole formed by patterning an insulating film formed on the processing substrate S, source gases include tantalum (Ta), titanium (Ti), tungsten (W), etc. The reaction gas is an ammonia gas that reacts with the raw material gas and deposits a metal thin film containing the constituent elements of these metals in the chemical structure.

  Then, after raising the temperature of the processing substrate S placed on the substrate stage 12 to a predetermined temperature, a step of introducing one of the source gas and the reaction gas and adsorbing the processing substrate S to the processing substrate S, and this one gas Once the vacuum is evacuated, the process of introducing the other and reacting on the processing substrate S is repeated, whereby a metal layer is stacked in the order of atomic layers to obtain a thin film having a predetermined thickness.

  Here, when a film is formed by the ALD method, there is a problem that the adhesion strength is weak. Therefore, in the present embodiment, the predetermined adhesion layer can be formed by the sputtering method prior to the thin film formation by the ALD method in the same vacuum chamber 11 so as to be opposed to the substrate stage 12 and above the vacuum chamber 12. Is provided with a sputtering cathode 41.

  The sputtering cathode 41 has a disk 41a made of a magnetic material, and the rotary table 41a is connected to a rotating shaft 41c of a driving means 41b such as a motor. A target 41c is attached at a predetermined position on the substrate stage 12 side of the disc 41a so as to be eccentric from the rotation center of the disc 41a. The disc 41a is positioned in the horizontal direction of the target 41c in the same plane. Constitutes a moving means for changing. Further, the rotary table 41a located behind the target 41c is provided with a magnet assembly 41d having a known structure so as to form a tunnel-like magnetic flux in front of the sputtering surface of the target 41c.

  The target 41c is manufactured by a known method according to the composition of the thin film to be formed on the processing substrate S. For example, as a target for forming an adhesion layer of a barrier film by sputtering, the main component is a constituent element of a metal contained in a source gas such as tantalum (Ta), titanium (Ti), tungsten (W), etc. It is. The target 41c is connected to a sputtering power source 42 that applies a DC voltage or a high-frequency voltage to the target 41c in order to generate plasma in front of the target 41c. In this case, the processing substrate S is also connected to the sputtering power source 42 in order to apply a bias voltage.

  A third gas introduction means 43 is provided in the vicinity of the target 41c. The gas introduction means 43 communicates with a gas source (not shown) via a gas pipe 43a provided with a mass flow controller, and can introduce a sputtering gas such as argon at a constant flow rate. The sputtering cathode 41, the sputtering power source 42 and the third gas introduction unit 43 constitute the sputtering film forming unit 4.

  By the way, when the film-forming apparatus 1 is configured so that film formation by the ALD method and film formation by the sputtering method can be performed in the same vacuum chamber 11 as described above, the surface (sputter surface) of the target 41c is There is a possibility that the raw material gas or adsorbed gas introduced during the film formation by the ALD method is adsorbed and contaminated. If the target 41c is contaminated, a problem such as inducing abnormal discharge occurs at the time of film formation by sputtering, which may hinder good film formation.

  In the present embodiment, the partition plate 5 is provided close to the sputtering cathode so as to isolate the first space 11a above the vacuum chamber 11 where the target 41c exists and the second space 11b where the substrate stage 12 exists. . As shown in FIG. 3, the partition plate 5 has an opening 51 where the target 41c faces so that film formation can be performed on the processing substrate S by sputtering when the disk 41a is rotated to a predetermined position. The formed opening 51 has an area larger than the outer shape of the target 41c.

  Thereby, since the target 41c is shielded by the partition plate 5 at the shielding position where the opening 51 and the target 41c do not coincide with each other, the target 41c of the raw material gas and the reactive gas introduced when the chemical film forming method is performed. Inflow to the vicinity is suppressed, thereby preventing contamination of the target 41c due to gas adsorption. In this case, a fourth gas introduction means 44 that enables introduction of a predetermined purge gas such as a rare gas is provided in the vicinity of the target 41c, and a gap between the shielding means 5 and the inner wall surface of the vacuum chamber 11 is provided. The raw material gas and the reaction gas are prevented from flowing through.

  Further, if the sputtering film forming means 41 is operated at the shielding position so as to perform pre-sputtering, even if the sputtering surface of the target 41c is slightly contaminated by the gas flowing in the vicinity of the target 41c, it is contaminated by pre-sputtering. Thus, it is possible to clean the portion, and it is possible to prevent the occurrence of problems such as inducing abnormal discharge during film formation by the sputtering method and to perform good film formation.

  The exhaust pipes 21 and 22 of the vacuum exhaust means 2 are respectively connected to the upper space 11a of the vacuum chamber 11 and the space 11b in which the substrate stage exists. For example, a switching valve (not shown) is disposed upstream of the vacuum pump. The switching valves are switched so that the spaces 11a and 11b can be evacuated independently. Further, a driving means 12a such as a motor for rotating the processing substrate S installed on the substrate stage 12 is provided so that the in-plane uniformity of the film thickness of the thin film formed on the processing substrate S is kept high. 12 is provided.

  By the way, in the film forming apparatus 1, if the rotating shaft 12b of the driving means 12a and the rotating shaft 41c of the rotating table 41a of the sputtering cathode 41 are arranged on the same axis, the second space 11b in which the film is formed by the ALD method. The volume increases, the adsorption rate of the source gas and reaction gas to the processing substrate S decreases, and the source gas and reaction gas introduced into the second space 52 cannot be rapidly evacuated. As a result, the deposition rate is lowered. For this reason, the rotating shaft 41c of the rotating table 41a is shifted from the rotating shaft 12b of the driving unit 12a, that is, the rotation center of the driving unit 12a. For this reason, the dimension of the horizontal direction of the vacuum chamber 11 can be set small, and the volume can be made small.

  On the other hand, when the film is formed on the processing substrate S by the sputtering method, it is necessary to set the distance between the target 41c and the processing substrate S in order to increase the uniformity of the thin film thickness within the surface of the processing substrate S. There is. For this reason, the distance between the target 41c and the processing substrate S is set in a range of 120 mm to 300 mm. Further, the distance between the head portions 31a and 32a and the processing substrate S is set in a range of 15 to 30 mm.

  Next, the operation when forming a barrier film prior to forming a buried layer for wiring in an interlayer connection hole formed in an insulating film using the film forming apparatus 1 of the present invention will be described. After the pretreatment process such as degassing of the surface of the processing substrate S is completed, the processing substrate S is placed on the substrate stage 12. In this state, the opening 51 and the target 41c are in an open position where they coincide. In this state, sputter gas is introduced into the vacuum chamber 11 via the third gas introduction means 43 while the processing substrate S is rotated at a predetermined rotational speed by the driving means 12a, and is supplied to the target 41c via the sputter power source 42. By applying a high frequency voltage, plasma is generated in front of the target 41c to sputter the target 41c, and an insulating film side adhesion layer is formed with a predetermined thickness on the insulating film.

  Next, the rotating plate 41a is rotated by a predetermined rotation angle and held by the driving unit 41b, and the processing substrate S is heated by operating the heating unit built in the substrate stage 12. Next, when the pressure in the second space 11b reaches a predetermined value and the processing substrate S reaches a predetermined temperature, a raw material gas is introduced through the first gas introduction means 31 to the surface of the processing substrate S. Adsorb source gas. Next, the supply of the source gas is stopped by controlling the mass flow controller provided in the first gas introduction means 31, and the vacuum is discharged until the pressure in the second space 11b reaches a predetermined value again.

  Next, a reactive gas is introduced through the second gas introducing means 32 to react with the raw material gas adsorbed on the surface of the processing substrate S. In this case, the reaction gas may be radicalized and introduced. Then, the mass flow controller provided in the second gas introduction means 32 is controlled to stop the supply of the reaction gas, and the vacuum is discharged until the pressure in the second space 11b reaches a predetermined value again. Then, by repeating the above procedure a desired number of times, a barrier film having a predetermined thickness is formed on the adhesion layer. In this case, pre-sputtering is performed by operating the sputtering film forming means 4 at the shielding position immediately before the film formation is completed by repeating the above procedure a desired number of times.

  After the barrier film having a predetermined thickness is formed and the pre-sputtering is completed, the disk 41a is rotated to the open position by the driving means 41b, the sputtering gas is introduced through the third gas introducing means 43, and the sputtering power source A high frequency voltage is applied to the target 41c via 42 to generate plasma in front of the target 41c, and the target 41c is sputtered to form a metal thin film, that is, a barrier film side adhesion layer on the surface of the barrier film.

  In the present embodiment, the target 41c is shielded by the shielding means 5 when the chemical film-forming method is performed. However, the present invention is not limited to this. For example, during film formation by the ALD method, While holding the target 41c in the open position, sputtering gas may be introduced, and a high frequency voltage may be applied to the target 41c to generate plasma. In this case, while the source gas and the reaction gas are reacted to form the barrier film on the surface of the processing substrate S, the processing substrate S is made incident with a metal whose main component is the same constituent element as the source gas by sputtering. Thus, the content of the constituent elements of the metal in the barrier film can be increased and reformed, and a dense barrier film can be obtained.

  When the source gas is an organometallic compound, this constituent element is incident on the surface of the processing substrate S by sputtering, so that decomposition is accelerated and impurities such as carbon are ejected from the barrier film. A membrane can be obtained. For example, when metal tantalum is used as the target 41c, organic tantalum gas is used as the source gas, and ammonia gas is used as the reaction gas, the metal tantalum is incident while the organic tantalum and ammonia gas react on the surface of the processing substrate S. Then, a tantalum nitride thin film is deposited on the surface of the processing substrate S.

  In the present embodiment, the disk 41a having the driving means 41b is used to move the target 41c in the same plane. However, the present invention is not limited to this. For example, a cathode having a known structure is used. A reciprocating moving means such as an air cylinder may be connected to move the cathode, that is, the target between the open position and the shield position.

  Furthermore, in the present embodiment, an example in which a barrier layer is formed between an insulating film and a copper wiring film is described as an example, and the ALD method is used as a chemical film forming method, but the present invention is not limited to this. Instead, the chemical film-forming method may be a CVD method, and can be applied as long as a thin film is formed by performing a sputtering method and a chemical film-forming method.

1 is a cross-sectional view schematically showing a film forming apparatus of the present invention. The figure explaining the gas ring used when performing a chemical film-forming method. The figure explaining a sputtering cathode.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Film-forming apparatus 11 Vacuum chamber 12 Substrate stage 2 Vacuum exhaust means 3 Chemical film-forming means 3a, 3b, 43 Gas introduction means 4 Sputtering film-forming means 41a Moving means 41c Target 5 Partition plate 51 Opening

Claims (7)

A sputtering film forming means for disposing a substrate stage capable of setting a processing substrate in a vacuum chamber, having a target provided facing the substrate stage, and capable of forming a film on the processing substrate by a sputtering method; Chemical deposition means having a gas introduction means and capable of forming a film on the processing substrate by a chemical film formation method, and this vacuum chamber includes a first space where a target exists and a second space where a substrate stage exists A film forming apparatus provided with a partition plate for partitioning;
The target is mounted on a moving means that enables the horizontal position of the target to be changed, and at any moving position, the target can be sputtered by generating plasma in the first space,
When you move the target in any position by said moving means, the film forming apparatus, characterized in that an opening facing this target to be subjected to film formation to form the partition plate by a sputtering method to process a substrate . The chemical film-forming method is an ALD method in which a source gas is introduced to adsorb the source gas on the surface of the processing substrate, and a reaction gas is introduced to react with the adsorbed source gas periodically. The film forming apparatus according to claim 1, wherein: The film forming apparatus according to claim 1, wherein a driving unit that rotates a processing substrate placed on the substrate stage is provided on the substrate stage. The moving means is a disk provided in the first space, and the rotation shaft of the driving means for rotating the disk is provided by shifting from the rotation center of the driving means for rotating the processing substrate. The film forming apparatus according to claim 3. The gas introducing means has a ring-shaped head portion provided on the shielding means side of the substrate stage so as to surround the substrate stage, and a predetermined gas is jetted to the head portion toward the processing substrate. The film forming apparatus according to claim 1, wherein a plurality of gas introduction holes are formed at predetermined intervals as described above. 6. The film forming apparatus according to claim 1, further comprising a gas introduction unit that enables introduction of a predetermined purge gas in the vicinity of the target. The film forming apparatus according to claim 1, wherein pre-sputtering is controlled by operating a sputtering film forming unit at a position where the target does not coincide with the opening.

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