The present disclosure relates to a method for manufacturing a semiconductor device and an apparatus for manufacturing a semiconductor device.
In an operation of manufacturing a semiconductor device, a processing of forming a metal film on a semiconductor wafer (hereinafter referred to as a wafer), which is a substrate for the manufacture of the semiconductor device, is performed. A ruthenium (Ru) film may be formed as this metal film. Patent Document 1 discloses a processing of forming an Ru film as a barrier film in a recess, which has a sidewall formed by an SiCOH film and a bottom surface made of copper, and then burying copper serving as a conductive path. Further, it describes supplying a diborane (B2H6) gas in order to increase adhesion between the Ru film and the SiCOH film before the formation of the Ru film.
The present disclosure is to prevent an increase in the electrical resistance of a ruthenium film formed on a conductive film, which is formed on a substrate for the manufacture of a semiconductor device.
A method for manufacturing a semiconductor device according to the present disclosure includes forming a ruthenium film on a conductive film formed on a substrate for manufacture of the semiconductor device, wherein the conductive film includes a metal that increases an electrical resistance between the conductive film and the ruthenium film by interfacial diffusion between the conductive film and the ruthenium film, and wherein the method includes an operation of forming the ruthenium film on the conductive film by alternately repeating a plurality of times: forming a ruthenium thin film by supplying a ruthenium raw material gas to the substrate on which the conductive film is formed; and then supplying a boron compound gas to the ruthenium thin film.
According to the present disclosure, it is possible to prevent an increase in the electrical resistance of a ruthenium film formed on a conductive film of a substrate for the manufacture of a semiconductor device.
An embodiment of a method of manufacturing a semiconductor device according to the present disclosure will be described. In this embodiment, as illustrated in
Before describing a specific method of manufacturing a semiconductor device, problems in a case of directly stacking the Ru film on the Co film will be described.
If the Ru film is stacked so as to directly come into contact with the Co film, interfacial diffusion occurs between the Co film and the Ru film when the wafer 100 is heated to a high temperature upon subsequent annealing. That is, metal atoms constituting the Co film and the Ru film move from one side to the other side. Thereby, an alloy of Co and Ru is created at a contact portion of the Co film and the Ru film, which increases an electrical resistance between the Co film and the Ru film.
Therefore, in the present embodiment, an Ru film 13 including boron (B) of B2H6 is formed on the Co film 11 (
The following method may be assumed as an example (comparative embodiment) of a method of forming the Ru film 13 including B on the Co film 11 using the above-described method.
First, a diborane (B2H6) gas is supplied to the wafer 100 with the Co film 11 being exposed as illustrated in
However, it was found that, when employing a method of exposing the Co film 11 to the B2H6 gas, and then supplying the Ru3(CO)12 gas, an oxide layer 20 of B is formed at an interface between the Co film 11 and the Ru film 13 including B, as illustrated in Comparative Example 1 to be described later. If such an oxide layer 20 is formed, an electrical resistance between the Ru film 13 and the Co film 11 will increase.
Therefore, the inventors studied the cause of the formation of the oxide layer 20 of B. Oxygen (O) adhering to a surface of the Co film 11, oxygen included in the Co film 11, and oxygen included in the Ru3(CO)12 gas are conceivable as the origin of oxygen forming the oxide layer 20. Further, a small amount of oxygen in the air passing through an O-ring that serves to airtightly keep a processing space for the wafer 100, or the like is conceivable as the origin of the oxygen forming the oxide layer 20. The inventors presumed whether the oxide layer 20 of B is produced by a reaction of such oxygen with B.
As described above, in the method described with reference to
Therefore, in an embodiment of a method of manufacturing a semiconductor device according to the present disclosure, in order to prevent the formation of such an oxide layer 20 of B, the Ru film 14 is formed on the Co film 11 by alternately repeating formation of an Ru thin film on the surface of the Co film 11, and then the supply of the B2H6 gas a plurality of times.
Hereinafter, each processing performed on the wafer 100 will be described with reference to
First, for example, the Ru3(CO)12 gas is supplied to the wafer 100 to form an Ru thin film 12 by chemical vapor deposition (CVD) (
By first forming the Ru thin film 12 and supplying the B2H6 gas to the Ru thin film 12 as described above, the Ru film 13 including B is formed while preventing contact between the Co film 11 and the B2H6 gas. As a result, it is possible to prevent the oxide layer 20 of B from being formed on the surface of the Co film 11. The following examples to be described later illustrate that the formation of the oxide layer 20 of B at an interface between the Co film 11 and the Ru film 14 may be prevented by applying the method of manufacturing the semiconductor device according to the present disclosure.
In a subsequent processing operation, the wafer 100 is subjected to annealing under an N2 gas atmosphere as a heat treatment. At this time, the aforementioned interfacial diffusion is prevented since the Ru film 14 includes B. That is, migration of Co constituting the Co film 11 to the Ru film 14 and migration of Ru constituting the Ru film 14 to the Co film 11 are inhibited, respectively. As a result, the formation of the alloy of Co and Ru is prevented.
By preventing the formation of the oxide layer 20 of B at the interface between the Co film 11 and the Ru film 14 and also by preventing the formation of the alloy of Ru and Co, it is possible to prevent an increase in the electrical resistance between the Co film 11 and the Ru film 14.
Further, with regard to supplying the B2H6 Gas and the Ru3(CO)12 gas, if both gases are simultaneously supplied to the wafer 100, the Ru film 14 is less likely to become amorphous. Therefore, there is a risk that the migration of Co to the Ru film 14 and the migration of Ru constituting the Ru film 14 to the Co film 11 may easily occur due to a low barrier property. Thus, the B2H6 gas and the Ru3(CO)12 gas may be alternately supplied by switching, rather than being supplied at the same time.
Further, if the thickness of the Ru thin film 12 formed at once becomes thick during alternately performing the formation of the Ru thin film 12 and the supply of the B2H6 gas as already described, B may not completely diffuse to an underlayer of the Ru thin film 12 when the B2H6 gas is supplied. If such a layer including no B or a layer including little B is formed, Co diffuses to the Ru film 14 or Ru diffuses to the Co film 11 when annealing is performed. Further, if the Ru thin film 12 is too thin, there is a risk that the number of repetitions increases, causing a reduced throughput. Therefore, the thickness of the Ru thin film 12 formed at once may be 0.268 nm or more and 2 nm or less. The lower limit of the thickness, 0.268 nm, is twice an atomic radius of Ru, 0.134 nm.
Further, in order to reliably prevent the formation of the oxide layer 20 of B, the Ru film 14 formed by stacking the Ru film 13 including B may have a film thickness of 2 nm or more, for example. This is because the Ru film 14 becomes a continuous film when having the film thickness of 2 nm or more. Further, when forming the Ru film 14 having a certain target film thickness, a film thickness of a stacked film portion in which two or more layers of the Ru film 13 including B are stacked may be less than the target film thickness. The Ru film 14 having the target film thickness may be formed by forming the stacked film in which the two or more layers of the Ru film 13 including B are stacked, and then forming an Ru film including no B on the stacked film.
Further, the Co film 11 may be formed by any method of PVD and CVD. Further, the Ru thin film 12 is also not limited to being formed by CVD, and may be formed by, for example, PVD.
In a case of the configuration described with reference to
Further, a ruthenium raw material gas for forming the Ru film 14 may be, for example, (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.
Further, a boron compound gas supplied to make the Ru thin film 12 include B may be any gas including boron (B), and is not limited to the B2H6 gas. For example, a gas including B such as monoborane, trimethylborane, triethylborane, dicarbadodecaborane, and decaborane may be used.
Subsequently, a film forming apparatus 41 for the Ru film 14 capable of performing the processing described in the above-described embodiment will be described. The film forming apparatus 41 corresponds to an embodiment of an apparatus of manufacturing a semiconductor device according to the present disclosure.
As illustrated in
A gas shower head 55 is provided in an upper portion inside the processing container 51. Reference numeral 56 in
In the above-described configuration, when the carrier gas is supplied to the raw material bottle 58, the Ru3(CO)12 is sublimated, and this Ru3(CO)12 gas is supplied to the gas shower head 55 together with the carrier gas.
Further, a gas supply path 71 is connected to the gas shower head. A proximal end side of the gas supply path 71 is branched, and is connected to a B2H6 gas source 72 and a source 73 for a carrier gas such as nitrogen (N2). Reference numerals V1 to V3 in
The film forming apparatus 41 includes a controller 80 (see
When the wafer 100 is processed as described above, the wafer 100 placed on the stage 52 of the film forming apparatus 41 is heated to, for example, 100 degrees C. to 250 degrees C., and an internal pressure of the processing container 51 is adjusted to, for example, 1.33 Pa (10 mTorr) to 13.3 Pa (100 mTorr). After the adjustment of the temperature and the pressure, the Ru3(CO)12 gas is supplied into the processing container 51 through the raw material bottle 58 at, for example, 100 sccm to 600 sccm, more specifically, for example, 300 sccm for 10 to 70 seconds, so that the Ru thin film 12 is formed. In addition, the supply time of the Ru3(CO)12 gas depends on the pressure and is about 30 seconds at 66.5 Pa (50 mTorr) and about 10 seconds at 22.2 Pa (16.6 mTorr).
Next, the B2H6 gas is supplied into the processing container 51 at, for example, 100 sccm to 2,000 sccm, and the N2 gas is supplied at, for example, 0 sccm to 1,000 sccm for the implementation of a processing. The supply time of these B2H6 gas and N2 gas is, for example, 10 seconds to 300 seconds. Then, the formation of the Ru thin film 12 and the supply of the B2H6 gas are alternately repeated a plurality of times, so that the Ru film 14 is formed.
<Example of Annealing after Formation of Ru Film>
In addition, an example of a processing condition upon annealing performed after the formation of the Ru film 14 is illustrated. For example, annealing sets the interior of the processing container 51 to an N2 atmosphere and to 133 Pa to 931 Pa (1 Torr to 7 Torr), more specifically, for example, to 667 Pa (5 Torr). In this pressure state, the wafer 100 is heated at, for example, 300 degrees C. to 500 degrees C. The heating of the wafer 100 is performed, for example, by the heater of the stage on which the wafer 100 is placed, similarly to a case where the wafer 100 is heated in each film forming apparatus 41.
A conductive film formed on the wafer 100 on which the Ru film 14 is formed using the method of manufacturing the semiconductor device and the film forming apparatus of the present disclosure is not limited to the example of the Co film 11 already described above. A technology of the present disclosure may be applied to any other conductive film as long as it includes a metal that increases an electrical resistance between the conductive film and the Ru film 15 by interfacial diffusion between the conductive film and the Ru film 15. A Ti film including titanium (Ti) or an Ni film including nickel (Ni) may be exemplified as such a conductive film.
In addition, it should be noted that the embodiments disclosed herein are exemplary in all respects and are not restrictive. The above-described embodiments may be omitted, replaced, modified, or combined in various forms without departing from the scope and spirit of the appended claims.
An experiment was conducted in order to verify the effects of the method of manufacturing the semiconductor device according to the present disclosure.
Example 1 is an example in which the Co film 11 is formed on the wafer 100 on which a silicon oxide (SiO2) is formed, and the Ru film 14 is formed on the surface of the Co film 11 according to the method of manufacturing the semiconductor device according to an embodiment.
Comparative Example 1 is an example in which, after the Co film 11 is formed on the same wafer 100 and then the B2H6 gas is supplied, the Ru3(CO)12 is continuously supplied to the wafer 100 to form the Ru film 16 (the Ru film 13 including B and the Ru film 15 illustrated in
Comparative Example 2 is an example in which the Co film 11 is formed on the same wafer 100, and then the Ru3(CO)12 is supplied to the wafer 100 to form the Ru film without performing the supply of the B2H6 gas.
For Example 1 and Comparative Example 1, atomic distribution in a depth direction from the surface of the wafer 100 was measured by energy dispersive X-ray spectroscopy (SEM EDX).
As illustrated in
Further, as illustrated in
In this regard, it can be said that in Comparative Example 1, an oxide (oxide layer 20 illustrated in
Further, for Example 1 and Comparative Example 2, annealing was performed, and atomic distribution in the depth direction of the wafer 100 before and after annealing was measured by secondary ion mass spectrometry (SIMS).
As illustrated in
This is conceivable because Co diffuses into the Ru film in Comparative Example 2, but the diffusion of Co into the Ru film 14 may be prevented in Example 1. Accordingly, in Example 1 in which the Ru film 14 was formed by alternately repeating the formation of the Ru thin film and the supply of the B2H6 gas a plurality of times, it can be said that the diffusion of Co into the Ru film 14 may be prevented, which may prevent an increase in an electrical resistance of the Ru film 14.
11: Co film, 12: Ru thin film, 13: Ru film including boron, 14: Ru film, 15: Ru film, 16: Ru film, 20: oxide layer, 30: SiO2 film, 100: wafer, 41: film forming apparatus, 51: processing container, 52: stage, 53: exhaust pipe, 54: vacuum exhaust mechanism, 55: gas shower head, 56: flow path, 57: gas supply path, 58: raw material bottle, 59: powder, 61: gas supply path, 62: carbon monoxide gas source, 63: gas supply equipment group, 64: gas supply equipment group, 71: gas supply path, 72: B2H6 gas source, 73: carrier gas source, 80: controller, F1: flow rate regulator, F2: flow rate regulator, V1: valve, V2: valve, V3: valve, V4: valve
Number | Date | Country | Kind |
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2020-163822 | Sep 2020 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2021/033970 | 9/15/2021 | WO |