This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2018-167232, filed on Sep. 6, 2018, the entire contents of which are incorporated herein by reference.
The present disclosure relates to an embedding method and a processing system.
A process is known in which a metal material such as ruthenium is embedded in, for example, a recess such as a trench, a via hole, or a contact hole provided in an insulating layer.
Patent Document 1 discloses a method of manufacturing a semiconductor device having a process of forming a ruthenium film or a ruthenium oxide film on a substrate using a gas obtained by vaporizing a ruthenium liquid source and an oxygen-containing gas.
Patent Document 1: Japanese laid-open publication No. 2008-22021
An aspect of the present disclosure provides an embedding method including: supplying a ruthenium-containing gas to a process chamber; and embedding ruthenium in a recess, which is formed in an insulating layer formed on a substrate, starting from a bottom portion of the recess using the ruthenium-containing gas, the bottom portion of the recess having a metal layer.
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present disclosure, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the present disclosure.
Reference will now be made in detail to various embodiments, examples of which are illustrated in the accompanying drawings. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. However, it will be apparent to one of ordinary skill in the art that the present disclosure may be practiced without these specific details. In other instances, well-known methods, procedures, systems, and components have not been described in detail so as not to unnecessarily obscure aspects of the various embodiments.
Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In each of the drawings, the same components are denoted by the same reference numerals, and redundant descriptions may be omitted.
First, a processing system for use in an embedding method according to an embodiment will be described with reference to
The processing system includes process chambers 11 to 14, a vacuum transfer chamber 20, load-lock chambers 31 and 32, an atmospheric transfer chamber 40, load ports 51 to 53, gate valves 61 to 68, and a control device 70.
The process chamber 11 has a stage 11a configured to place a semiconductor wafer W (hereinafter referred to as “wafer W”) thereon, and is connected to the vacuum transfer chamber 20 via the gate valve 61. Similarly, the process chamber 12 has a stage 12a configured to place a wafer W thereon, and is connected to the vacuum transfer chamber 20 via the gate valve 62. The process chamber 13 has a stage 13a configured to place a wafer W thereon, and is connected to the vacuum transfer chamber 20 via the gate valve 63. The process chamber 14 has a stage 14a configured to place a wafer W thereon, and is connected to the vacuum transfer chamber 20 via the gate valve 64. The interior of the process chambers 11 to 14 are depressurized to predetermined vacuum atmospheres, and desired processes (e.g., an etching process, a film-forming process, a cleaning process, an ashing process, and the like) are performed on wafers W in the interiors of the process chambers 11 to 14. Operations of respective components for performing the processes in the process chambers 11 to 14 are controlled by the control device 70.
The interior of the vacuum transfer chamber 20 is depressurized to a predetermined vacuum atmosphere. In addition, a transfer mechanism 21 is provided in the vacuum transfer chamber 20. The transfer mechanism 21 transfers the wafers W to the process chambers 11 to 14 and to the load-lock chambers 31 and 32. Operation of the transfer mechanism 21 is controlled by the control device 70.
The load-lock chamber 31 has a stage 31a configured to mount a wafer W thereon, is connected to the vacuum transfer chamber 20 via the gate valve 65, and is connected to the atmospheric transfer chamber 40 via the gate valve 67. Similarly, the load-lock chamber 32 has a stage 32a configured to mount a wafer W thereon, is connected to the vacuum transfer chamber 20 via the gate valve 66, and is connected to the atmospheric transfer chamber 40 via the gate valve 68. The interior of each of the load-lock chambers 31 and 32 is configured to be switchable between an atmospheric atmosphere and a vacuum atmosphere. In addition, the switching between the vacuum atmosphere and the atmospheric atmosphere in each of the load-lock chambers 31 and 32 is controlled by the control device 70.
The interior of the atmosphere transfer chamber 40 is kept in an atmospheric atmosphere, and a downflow of, for example, clean air is formed in the atmosphere transfer chamber 40. In addition, a transfer mechanism 41 is provided in the vacuum transfer chamber 40. The transfer mechanism 41 transfers the wafers W to the load-lock chambers 31 and 32 and to carriers C in the load ports 51 to 53 described later. Operation of the transfer mechanism 41 is controlled by the control device 70.
The load ports 51 to 53 are provided on a long side wall of the atmospheric transfer chamber 40. A carrier C in which wafers W are accommodated or an empty carrier C is mounted in each of the load ports 51 to 53. For example, front opening unified pods (FOUPs) may be used as the carriers C.
The gate valves 61 to 68 can be opened and closed. The opening and closing of the gate valves 61 to 68 are controlled by the control device 70.
The control device 70 controls the entire processing system by performing, for example, the operations of the process chambers 11 to 14, the operations of the transfer mechanisms 21 and 41, the opening and closing of the gate valves 61 to 68, and the switching operations between the vacuum atmosphere and the atmospheric atmosphere in the load-lock chambers 31 and 32.
Next, an example of the operation of the processing system will be described. For example, the control device 70 opens the gate valve 67 and controls the transfer mechanism 41 to transfer the wafer W accommodated in, for example, the carrier C in the load port 51 to the stage 31a of the load-lock chamber 31. Then, the control device 70 closes the gate valve 67 and sets the interior of the load-lock chamber 31 to a vacuum atmospheres.
The control device 70 opens the gate valves 61 and 65 and controls the transfer mechanism 21 to transfer the wafer W in the load-lock chamber 31 to the stage 11a of the process chamber 11. Then, the control device 70 closes the gate valves 61 and 65 and operates the process chamber 11. Therefore, a predetermined process (e.g., a pre-cleaning process described later) is performed on the wafer W in the process chamber 11.
Next, the control device 70 opens the gate valves 61 and 63 and controls the transfer mechanism 21 to transfer the wafer W processed in the process chamber 11 to the stage 13a of the process chamber 13. Then, the control device 70 closes the gate valves 61 and 63 and operates the process chamber 13. Thus, a predetermined process (e.g., an embedding process described later) is performed on the wafer W in the process chamber 13.
The control device 70 may transfer the wafer W processed in the process chamber 11 to the stage 14a of the process chamber 14 configured to perform a process similar to the process in the process chamber 13. In the present embodiment, the wafer W in the process chamber 11 is transferred to the process chamber 13 or to the process chamber 14 depending on the operation status of the process chamber 13 and the process chamber 14. Thus, the control device 70 may perform a predetermined process (e.g., a ruthenium embedding process described later) on a plurality of wafers W in parallel using the process chamber 13 and the process chamber 14. As a result, it is possible to improve productivity.
The control device 70 controls the transfer mechanism 21 to transfer the wafer W processed in the process chamber 13 or 14 to the stage 31a of the load-lock chamber 31 or to the stage 32a of the load-lock chamber 32. Then, the control device 70 sets the interior of the load-lock chamber 31 or the load-lock chamber 32 to the atmospheric atmosphere. The control device 70 opens the gate valve 67 or the gate valve 68 and controls the transfer mechanism 41 to transfer the wafer W in the load-lock chamber 31 or the load-lock chamber 32 to the carrier C, for example, in the load port 53.
As described above, according to the processing system illustrated in
Next, an example of a structure of a processing apparatus 600 that implements a process chamber for use in an embedding method, which is a predetermined process according to an embodiment, will be described with reference to
A main body container 601 is a bottomed container having an opening at an upper portion thereof. A support member 602 supports a gas ejection mechanism 603. In addition, the support member 602 closes the upper opening of the main body container 601 such that the main body container 601 is sealed to form a process chamber 13 (see also
A stage 605 is a member on which a wafer W is placed, and is illustrated as the stage 13a in
The shaft of the temperature control jacket 608 penetrates the bottom portion of the main body container 601. The lower end portion of the temperature control jacket 608 is supported by the lift mechanism 610 via the lift plate 609 disposed below the main body container 601. A bellows 611 is installed between the bottom portion of the main body container 601 and the lift plate 609 such that the airtightness in the main body container 601 is maintained irrespective of the vertical movement of the lift plate 609.
When the lift mechanism 610 moves the lift plate 609 upward and downward, the stage 605 moves upward and downward between a processing position (see
Lift pins 612 support the lower surface of the wafer W and lift the wafer W from the mounting surface of the stage 605 when the wafer W is delivered between the stage 605 and the external transfer mechanism 21 (see
When the stage 605 is moved to the processing position of the wafer W (see
An annular member 614 is disposed above the stage 605. When the stage 605 is moved to the processing position of the wafer W (see
A chiller unit 615 circulates a coolant (e.g., cooling water) in a flow path 608a formed in the plate of the temperature control jacket 608 via pipes 615a and 615b.
A heat transfer gas supply 616 supplies a heat transfer gas (e.g., He gas) to a space between the rear surface of the wafer W placed on the stage 605 and the mounting surface of the stage 605 through a pipe 616a.
A purge gas supply 617 causes a purge gas to flow through a pipe 617a, a gap formed between the support 605a of the stage 605 and the hole in the temperature control jacket 608, a flow path (not illustrated) formed between the stage 605 and the heat insulating ring 607 and extending outward in a radial direction, and a vertical flow path (not illustrated) formed in the outer peripheral portion of the stage 605. Through these flow paths, the purge gas (e.g., CO2 gas) is supplied to a space between the lower surface of the annular member 614 and the upper surface of the stage 605. Thus, the process gas is prevented from flowing into the space between the lower surface of the annular member 614 and the upper surface of the stage 605, thereby preventing a film from being formed on the lower surface of the annular member 614 or the upper surface of the outer peripheral portion of the stage 605.
The loading and unloading port 601a for loading and unloading the wafer W and a gate valve 618 for opening and closing the loading and unloading port 601a are provided on the side wall of the main body container 601. The gate valve 618 is illustrated in
An exhauster 619 including a vacuum pump and the like is connected to the lower side wall of the main body container 601 via an exhaust pipe 601b. The interior of the main body container 601 is evacuated by the exhauster 619 such that the interior of the process chamber 13 is set to and maintained at a predetermined vacuum atmosphere (e.g., 1.33 Pa).
A control device 620 controls the operation of the processing apparatus 600 by controlling the gas supply 604, the heater 606, the lift mechanism 610, the chiller unit 615, the heat transfer gas supply 616, the purge gas supply 617, the gate valve 618, the exhauster 619, and the like. The control device 620 may be provided independently from the control device 70 (see
An example of the operation of the processing apparatus 600 will be described. At a start of the operation, the interior of the process chamber 13 is set to a vacuum atmosphere by the exhauster 619, and the stage 605 is moved to the delivery position.
The control device 620 opens the gate valve 618. A wafer W is placed on the lift pins 612 by the external transfer mechanism 21. When the transfer mechanism 21 goes out of the loading and unloading port 601a, the control device 620 closes the gate valve 618.
The control device 620 controls the lift mechanism 610 to move the stage 605 to the processing position. At this time, as the stage 605 moves upward, the wafer W placed on the lift pins 612 is placed on the mounting surface of the stage 605. In addition, the annular member 614 comes into contact with the outer peripheral portion in the upper surface of the wafer W, and the wafer W is pressed against the mounting surface of the stage 605 by the weight of the annular member 614.
At the processing position, the control device 620 operates the heater 606 and controls the gas supply 604 to supply the process gas such as ruthenium-containing gas or the carrier gas from the gas ejection mechanism 603 to the process chamber 12. As a result, a predetermined process such as film formation is performed on the wafer W. The gas after processing the wafer W passes through the flow path above the upper surface of the annular member 614, and is exhausted by the exhauster 619 through the exhaust pipe 601b.
At this time, the control device 620 controls the heat transfer gas supply 616 to supply the heat transfer gas between the rear surface of the wafer W placed on the stage 605 and the mounting surface of the stage 605. In addition, the control device 620 controls the purge gas supply 617 to supply the purge gas to the space between the lower surface of the annular member 614 and the upper surface of the stage 605. The purge gas passes through the flow path below the lower surface of the annular member 614, and is exhausted by the exhauster 619 through the exhaust pipe 601b.
When the predetermined process ends, the control device 620 controls the lift mechanism 610 to move the stage 605 to the delivery position. At this time, as the stage 605 moves downward, the annular member 614 is engaged with the engagement portion (not illustrated). In addition, the lower ends of the lift pins 612 are brought into contact with the contact member 613, and the heads of the lift pins 612 protrude from the mounting surface of the stage 605. Thus the wafer W are lifted from the mounting surface of the stage 605.
The control device 620 opens the gate valve 618, and the wafer W placed on the lift pins 612 is unloaded by the external transfer mechanism 21. When the transfer mechanism 21 goes out of the loading and unloading port 601a, the control device 620 closes the gate valve 618.
As described above, according to the processing apparatus 600 illustrated in
Next, a method for embedding ruthenium in a recess formed in a wafer W according to an embodiment will be described with reference to
In
According to the experimental results, a ruthenium film having a thickness of about 6 nm was formed on tungsten under a condition for forming a ruthenium film having a thickness of 1 nm on a silicon oxide film. That is to say, it was found that the selection ratio is about 6.0.
In addition, a ruthenium film having a thickness of about 4.0 nm was formed on tungsten under a condition of forming a ruthenium film having a thickness of 1 nm on a silicon film. Thus, it was found that the selection ratio is about 4.0. Similarly, a ruthenium film having a thickness of about 9.0 nm was formed on tungsten under a condition of forming a ruthenium film having a thickness of 1 nm on a titanium film. Thus, it was found that the selection ratio is about 9.0. Further, a ruthenium film having a thickness of about 2.0 nm was formed on tungsten under a condition of forming a ruthenium film having a thickness of 1 nm on a silicon nitride film. Thus, it was found that the selection ratio is about 2.0.
As the selection ratio of tungsten to each of the silicon oxide film, the silicon film, the titanium film, and the silicon nitride film is larger, a ruthenium film is more easily formed on tungsten, and a ruthenium film is less easily formed on each of the corresponding materials. According to the experimental results, the corresponding materials are the titanium film, the silicon oxide film, the silicon film, and the silicon nitride film in the descending order of the selection ratio. In addition, even in the silicon nitride film having the smallest selection ratio, the selection ratio was about 2.0, which is larger than 1. Accordingly, it was found that in any of the materials, a ruthenium film is more easily deposited on tungsten than on each material, and that, even in the silicon nitride film having the smallest selection ratio, the ruthenium film is formed on tungsten at a film forming rate of about twice that on the silicon nitride film.
A method of embedding ruthenium in a recess formed in a wafer W according to the embodiment will be described with reference to
The insulating film 110 formed on the base film 101 is formed of, for example, a silicon-containing film such as a silicon oxide film, a silicon film, or a silicon nitride film. However, it is possible to select any material as the material of the insulating film 110 as long as a film forming rate of ruthenium on the metal layer 102 is higher than a film forming rate of ruthenium on the insulating film 110. The insulating film 110 is not limited to a single-layer film of a silicon oxide film, a silicon film, or a silicon nitride film, and may be any of laminated films in which different silicon-containing films are combined, such as a laminated film of a silicon oxide film and a silicon nitride film. In addition, a titanium film may be used instead of the silicon-containing film. A recess 113 such as a trench, a via hole, or a contact hole is formed in the insulating film 110, and the metal layer 102 is exposed from the bottom portion of the recess 113.
As the process chamber 13 in which the ruthenium embedding process is performed, for example, a CVD apparatus, an example of which is illustrated in
A ruthenium film is formed by thermal decomposition of Ru3(CO)12 adsorbed to the surface of the wafer W. Here, in the film forming method based on the thermal decomposition of Ru3(CO)12, the film forming rate of ruthenium on the surface of the metal layer 102, i.e., tungsten, is about six times the film forming rate of ruthenium on the side surface of the insulating film 110, i.e., the silicon oxide film formed in the recess 113 (see
Using this selectivity, as indicated by arrows in
Although the ruthenium embedding process in which a film is formed using Ru3(CO)12 has been described, the ruthenium-containing gas is not limited thereto, and a gas containing Ru3(CO)12 (but not containing oxygen gas), (2,4-dimethylpentadienyl) (ethylcyclopentadienyl) ruthenium: (Ru(DMPD)(EtCp)), bis (2,4-dimethylpentadienyl) ruthenium: (Ru(DMPD)2), 4-dimethylpentadienyl (methylcyclopentadienyl) ruthenium: (Ru(DMPD)(MeCp)), bis (cyclopentadienyl) ruthenium: (Ru(C5H5)2), cis-dicarbonyl bis (5-methylhexane-2,4-dionate) ruthenium (II), bis (ethylcyclopentadienyl) Ruthenium (II): Ru(EtCp)2, or the like may be used.
In some embodiments, the ruthenium embedding process may use a ruthenium film forming method in which no oxygen gas is used as a gas supplied to the process chamber 13. This makes it possible to prevent the surface of the metal layer 102 on the bottom portion of the recess 113 from being oxidized by an oxygen gas.
Next, an embedding method according to a modification of the embodiment will be described with reference to
In this modification, an experiment was conducted to determine how a selection ratio is affected when a pre-cleaning process was performed and when a pre-cleaning process was not performed as the pre-process of the ruthenium embedding process.
In the experiment of
In the pre-cleaning process, a metal oxide film formed on the surface of the metal layer 102 is removed. On the surface of the metal layer 102 exposed on the bottom portion of the recess 113, for example, a metal oxide film naturally oxidized by, for example, oxygen in the atmospheric atmosphere may be formed.
Therefore, in this experiment, it was verified which difference exists in ruthenium film formation between when the metal oxide film formed on the surface of tungsten is removed in the pre-cleaning process and when the pre-cleaning process is not performed.
From the experimental results represented in
Therefore, in the embedding method according to the modification of the embodiment, a metal oxide film 102a formed on the surface of the metal layer 102 illustrated in
In this modification, the pre-cleaning process is performed in the process chamber 11 (see
In some embodiments, the ruthenium embedding process according to this modification may use a ruthenium film forming method in which no oxygen gas is used as a gas supplied to the process chamber 13. This makes it possible to prevent the surface of the metal layer 102 on the bottom portion of the recess 113 from being oxidized again by an oxygen gas.
In the ruthenium embedding process according to the modification, as indicated by long arrows in
In the first comparative example described above, since the liner film 310 made of TaN having a specific resistance higher than that of ruthenium is formed, the electric resistance cannot be reduced.
In contrast, in the embedding method according to the embodiment and the modification thereto, the recess 113 is embedded with ruthenium with good coverage. In addition, the embedded ruthenium does not diffuse into the tungsten metal layer 102. Thus, it is possible to reduce the electrical resistance compared with the case of using a liner film or a barrier film containing metal having a high specific resistance.
As described above, according to the embedding method of the embodiment and the modification, it is possible to implement a low-resistance ruthenium embedding method. In addition, according to the processing system of the embodiment and the modification, it is possible to continuously perform the pre-cleaning process and the ruthenium-embedding process without breaking vacuum while the processes are performed on a wafer W by the process chambers.
The number of process chambers 11 to 14, the number of vacuum transfer chambers 20, the number of load-lock chambers 31 and 32, the number of atmospheric transfer chambers 40, the number of load ports 51 to 53, and the number of gate valves 61 to 68 are not limited to those illustrated in
That is to say, the number of process chambers of the present disclosure may be one, or may be two or more in some embodiments. The process chambers of the present disclosure may include a first process chamber in which the pre-cleaning process of removing a metal oxide film on the surface of the metal layer from a substrate having the metal layer on the bottom portion of the recess formed in the insulating layer, and a second process chamber in which the ruthenium embedding process of embedding ruthenium from the bottom portion of the recess. When the ruthenium embedding process is performed in two process chambers, the process chambers of the present disclosure may include the first process chamber, the second process chamber, and a third process chamber in which the ruthenium embedding process of embedding ruthenium from the bottom portion of the recess.
The process chamber of the present disclosure may be applicable to any types of apparatuses including a capacitively coupled plasma (CCP) apparatus, an inductively coupled plasma (ICP) apparatus, a radial line slot antenna (RLSA) apparatus, an electron cyclotron resonance plasma (ECR) apparatus, and a helicon wave plasma (HWP) apparatus, and the like.
According to the present disclosure, it is possible to provide a low-resistance ruthenium embedding method and a processing system.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the disclosures. Indeed, the embodiments described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the disclosures. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosures.
Number | Date | Country | Kind |
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2018-167232 | Sep 2018 | JP | national |