Method for forming a copper film

Abstract

The present invention relates to a method for forming a copper film on a substrate in a chamber, comprising the steps of a) injecting a copper-containing precursor onto the substrate, b) injecting a first purge gas onto the substrate, c) forming a plasma on the substrate using hydrogen (H2), and d) injecting a mixed gas containing a hydrogen-containing gas and a nitrogen-containing gas onto the substrate, wherein step d) involves continuously injecting the mixed gas while steps a) through c) are performed.

Description

Technical Field

[0001] The present invention relates to a method for forming a copper film on a substrate.

Background Art

[0002] Generally, in order to manufacture semiconductor devices, display devices, solar cells, etc., a predetermined thin film layer, thin film circuit pattern, or optical pattern must be formed on a substrate. For this purpose, processing steps for the substrate are performed, such as a deposition step of depositing a thin film of a specific substance on the substrate, a photolithography step of selectively exposing the thin film using a photosensitive substance, and an etching step of removing the thin film of the selectively exposed portion to form a pattern. Such processing steps can include a copper film forming step of forming a copper film on the substrate.

[0003] The copper film forming step can be performed by spraying a copper (Cu) - containing precursor onto the substrate to form a copper film. However, since copper has a strong property of sticking to each other as the temperature rises, an agglomeration issue where copper sticks to each other can occur during the copper film forming step. As a result, the copper film formed through the copper film forming step is not formed so as to be continuously connected but is formed sparsely, so there is a problem of low film quality.

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present invention has been devised to solve the above - described problems, and is for providing a copper film forming method capable of solving the agglomeration problem caused by using copper.

Means for Solving the Problems

[0005] In order to solve the above - described problems, the present invention can include the following configurations.

[0006] The copper film formation method according to the present invention is a method for forming a copper film on a substrate in a chamber, and includes the steps of a) injecting a copper-containing precursor onto the substrate, b) injecting a first purge gas onto the substrate, c) forming a plasma on the substrate using hydrogen (H2), and d) injecting a mixed gas containing a hydrogen-containing gas and a nitrogen-containing gas onto the substrate. The mixed gas can be continuously injected in step d) from step a) through to step c).

[0007] In the copper film formation method according to the present invention, step c) can be performed after repeating a cycle of sequentially performing steps a) and b) N times (where N is a natural number greater than 1).

[0008] The copper film formation method according to the present invention can be performed by repeating the cycle of sequentially carrying out steps a), b), and c) M times (where M is a natural number greater than 1).

[0009] In the copper film formation method according to the present invention, the nitrogen-containing gas may include at least one of nitrogen (N2), ammonia (NH3), plasma-activated nitrogen (N2), and plasma-activated ammonia (NH3).

[0010] The copper film formation method according to the present invention may include a step of treating the substrate with a plasma using hydrogen or oxygen (O2) before step a) is performed.

[0011] In the copper film formation method according to the present invention, steps a) to d) can be carried out when the internal temperature of the chamber is 50°C or higher and 300°C or lower.

[0012] The copper film formation method according to the present invention may include the step of e) injecting a second purge gas onto the substrate. Step e) can be performed after step c) has been performed.

[0013] The copper film forming method according to the present invention can be performed by repeating a cycle of steps a), b), c), and e) sequentially R times (where R is a natural number greater than 1). Step d) allows for the continuous injection of the mixed gas while the cycle is repeated. [Effects of the Invention]

[0014] According to the present invention, the following effects can be obtained.

[0015] The present invention is embodied in a method of continuously injecting a gas containing at least one of a hydrogen-containing gas and a nitrogen-containing gas while forming a copper film using a copper-containing precursor. This allows the present invention to rapidly decompose the ligands of copper organisms and continuously weaken the tendency of copper to clump together. Therefore, the present invention can solve the problem of copper aggregation during the process of forming a copper film. Thus, the present invention can improve the film quality of the copper film by improving the morphology of the copper film and forming the copper film in a continuously connected manner. Furthermore, the present invention can increase the growth per cycle (GPC) for forming the copper film, thereby shortening the process time required for copper film formation. [Brief explanation of the drawing]

[0016] [Figure 1] This is a schematic diagram showing an example of a substrate processing apparatus in which the copper film formation method according to the present invention is performed. [Figure 2] This is a schematic side cross-sectional view of a gas injection section in an example of a substrate processing apparatus in which the copper film forming method according to the present invention is performed. [Figure 3] This is a schematic side cross-sectional view of a gas injection section in an example of a substrate processing apparatus in which the copper film forming method according to the present invention is performed. [Figure 4] This is a schematic side cross-sectional view showing a copper film formed on a substrate by the copper film formation method according to the present invention. [Figure 5]This is a schematic flowchart of a copper film forming method according to the present invention. [Figure 6] This is a timing diagram regarding the time point when gas injection and plasma generation are performed in the substrate processing apparatus according to the present invention. [Figure 7] This is a schematic flowchart of a copper film forming method according to a modified embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0017] Hereinafter, embodiments of the copper film forming method according to the present invention will be described in detail with reference to the accompanying drawings. In describing the embodiments of the present invention, when it is described that a certain structure is formed "on" or "under" another structure, such a description should be interpreted to include not only the case where these structures are in contact with each other, but also the case where a third structure is interposed between these structures. On the other hand, in the timing diagram of FIG. 6, the horizontal axis represents time, and the vertical axis can represent the gas flow rate or the gas injection pressure.

[0018] Referring to FIGS. 1 to 4, the copper film forming method according to the present invention is for forming a copper film 110 on a substrate 100. The substrate 100 can be a silicon substrate, a glass substrate, a metal substrate, or the like. The copper film 110 can be provided in a semiconductor element, a display device, a solar cell, or the like. For example, the copper film 110 can be provided in a capacitor.

[0019] The copper film forming method according to the present invention can be performed by a substrate processing apparatus 1. Before describing an embodiment of the copper film forming method according to the present invention, an example of the substrate processing apparatus 1 is as follows.

[0020] Referring to FIGS. 1 to 3, the substrate processing apparatus 1 can include a chamber 2, a substrate support portion 3, and an injection portion 4.

[0021] Chamber 2 provides a processing space 200. In the processing space 200, a process for forming a copper film can be performed. The processing space 200 can be disposed inside Chamber 2. Chamber 2 can be coupled with an exhaust port (not shown) for exhausting gas from the processing space 200. Inside Chamber 2, a substrate support 3 and an injection unit 4 can be disposed.

[0022] The substrate support 3 supports the substrate 100. The substrate support 3 can support one substrate 100 or a plurality of substrates 100. When a plurality of substrates 100 are supported by the substrate support 3, a processing process for the plurality of substrates 100 can be performed at once. The substrate support 3 can be coupled with Chamber 2. The substrate support 3 can be disposed inside Chamber 2.

[0023] The injection unit 4 injects gas toward the substrate support 3. The injection unit 4 can be connected to a gas storage unit 40. In this case, the injection unit 4 can inject the gas supplied from the gas storage unit 40 toward the substrate support 3. The injection unit 4 can be disposed inside Chamber 2. The injection unit 4 can be disposed so as to face the substrate support 3. The injection unit 4 can be disposed above the substrate support 3. The processing space 200 can be disposed between the injection unit 4 and the substrate support 3. The injection unit 4 can be coupled with a lid (not shown). The lid can be coupled with Chamber 2 so as to cover the upper portion of Chamber 2.

[0024] The injection unit 4 can include a first gas flow path 4a and a second gas flow path 4b.

[0025] The first gas channel 4a is for injecting the first gas. One side of the first gas channel 4a can be connected to the gas storage unit 40 via piping, hoses, gas blocks, etc. The other side of the first gas channel 4a can communicate with the processing space 200. As a result, the first gas supplied from the gas storage unit 40 can flow along the first gas channel 4a and then be injected into the processing space 200 through the first gas channel 4a. The first gas channel 4a functions as a channel for the flow of the first gas and can also function as an injection port for injecting the first gas into the processing space 200.

[0026] The second gas channel 4b is for injecting the second gas. The second gas and the first gas can be different gases. For example, if the first gas is the source gas, the second gas can be the reactant gas. One side of the second gas channel 4b can be connected to the gas storage unit 40 via piping, hoses, gas blocks, etc. The other side of the second gas channel 4b can communicate with the processing space 200. As a result, the second gas supplied from the gas storage unit 40 can flow along the second gas channel 4b and then be injected into the processing space 200 through the second gas channel 4b. The second gas channel 4b can function as a channel for the flow of the second gas and as an injection port for injecting the second gas into the processing space 200.

[0027] The second gas channel 4b and the first gas channel 4a can be arranged to be spatially separated from each other. This allows the second gas supplied from the gas storage unit 40 to the second gas channel 4b to be injected into the processing space 200 without passing through the first gas channel 4a. The first gas supplied from the gas storage unit 40 to the first gas channel 4a can be injected into the processing space 200 without passing through the second gas channel 4b. The second gas channel 4b and the first gas channel 4a can inject gas toward different parts of the processing space 200.

[0028] For example, as shown in Figure 2, the injection unit 4 may include a first plate 41 and a second plate 42.

[0029] The first plate 41 is positioned above the second plate 42. The first plate 41 and the second plate 42 can be positioned spaced apart from each other. The first plate 41 can have first gas holes 411 formed thereon. Each of the first gas holes 411 can function as a passage for the flow of a first gas. Each of the first gas holes 411 can belong to the first gas flow path 4a. The first plate 41 can have second gas holes 412 formed thereon. Each of the second gas holes 412 can function as a passage for the flow of a second gas. Each of the second gas holes 412 can belong to the second gas flow path 4b. A protruding member 413 can be attached to the first plate 41. The protruding member 413 can protrude from the lower surface of the first plate 41 toward the second plate 42. Each of the first gas holes 411 can be formed penetrating the first plate 41 and the protruding member 413.

[0030] An opening 421 can be formed in the second plate 42. The opening 421 can be formed through the second plate 42. The opening 421 can be positioned corresponding to each of the protruding members 413. This allows the protruding members 413 to be formed to a length such that they are inserted into each of the openings 421, as shown in Figure 2. Although not shown in the figure, the protruding members 413 can also be formed to a length such that they are positioned above each of the openings 421. The protruding members 413 can also be formed to a length that protrudes below the second plate 42. The second gas hole 412 can be positioned to inject gas toward the upper surface of the second plate 42. Although not shown in the figure, the lower surface of the first plate 41 can also be formed flat without the protruding members 413.

[0031] The injection unit 4 can generate plasma using the second plate 42 and the first plate 41. In this case, a plasma power source such as RF power can be applied to the first plate 41 and the second plate 42 can be grounded. Alternatively, the first plate 41 can be grounded and the plasma power source can be applied to the second plate 42.

[0032] For example, as shown in Figure 3, the second plate 42 can also have a plurality of first openings 422 and a plurality of second openings 423.

[0033] The first opening 422 can be formed through the second plate 42. The second opening 423 can be formed through the second plate 42. The second plate 42 and the first plate 41 can be spaced apart from each other. The lower surface of the first plate 41 facing the second plate 42 can be formed flat without a protruding member 413 (shown in Figure 2). The first gas and the second gas can each be supplied into the space between the first plate 41 and the second plate 42 through the first gas hole 411 and the second gas hole 412, and then injected into the processing space 200 through the first opening 422 and the second opening 423. In this case, if the supply of the first gas through the first gas hole 411 and the supply of the second gas through the second gas hole 412 are done simultaneously, the first gas and the second gas can be mixed in the space between the first plate 41 and the second plate 42, and then injected into the processing space 200 through the first opening 422 and the second opening 423.

[0034] On the other hand, the first opening 422 can be positioned vertically below each of the first gas holes 411. In this case, the first opening 422 and the first gas holes 411 can be positioned on the same vertical line. Although not shown in the figure, the first opening 422 and the first gas holes 411 can also be positioned offset from each other. In this case, the first opening 422 and the first gas holes 411 can be positioned so that they do not overlap, or so that only a portion of them overlap.

[0035] On the other hand, the second opening 423 can be positioned vertically below each of the second gas holes 412. In this case, the second opening 423 and the second gas holes 412 can be positioned on the same vertical line. Although not shown in the figure, the second opening 423 and the second gas holes 412 can also be positioned offset from each other. In this case, the second opening 423 and the second gas holes 412 can be positioned so that they do not overlap, or so that only a portion of them overlap.

[0036] The injection unit 4 may include a third gas flow path 4c.

[0037] The third gas channel 4c is for injecting the third gas. One side of the third gas channel 4c can be connected to the gas storage unit 40 via piping, hoses, gas blocks, etc. The other side of the third gas channel 4c can communicate with the processing space 200. As a result, the third gas supplied from the gas storage unit 40 can flow along the third gas channel 4c and then be injected into the processing space 200 through the third gas channel 4c. The third gas channel 4c can function as a channel for the flow of the third gas and as an injection port for injecting the third gas into the processing space 200. The third gas channel 4c, the second gas channel 4b, and the first gas channel 4a can also be arranged to be spatially separated from each other. The third gas can also be supplied to the space between the first plate 41 and the second plate 42 via the third gas channel 4c and then injected into the processing space 200 through openings 422 and 423 formed in the second plate 42.

[0038] The copper film formation method according to the present invention can be carried out via such a substrate processing apparatus 1.

[0039] Referring to Figures 1 to 6, the copper film formation method according to the present invention is for forming a copper film 110 on a substrate 100 in a chamber 2. The copper film formation method according to the present invention may include steps a) (S11), b) (S12), c) (S13), and d) (S20).

[0040] a) Step (S11) involves injecting a copper-containing precursor onto the substrate 100. Step (S11) can be performed by injecting the copper-containing precursor into the processing space 200 using the injection unit 4. In this case, the injection unit 4 can inject the copper-containing precursor via the first gas flow path 4a. Through step (S11), an adsorption step can be performed in which a copper layer containing copper is adsorbed.

[0041] b) Step (S12) involves injecting a first purge gas onto the substrate 100. Step (S12) can be performed by injecting the first purge gas into the processing space 200 using an injection unit 4. In this case, the injection unit 4 can inject the first purge gas through at least one of the first gas flow path 4a and the second gas flow path 4b. The first purge gas may be an inert gas such as argon (Ar). Step (S12) can be used to perform a purging step in which copper-containing precursors and other materials not used in the adsorption step are purged from the processing space 200.

[0042] Step (S13) involves forming a plasma on the substrate 100 using hydrogen (H2). Step (S13) can be carried out by forming a plasma in the processing space 200 using hydrogen. Hydrogen for forming the plasma can be injected into the processing space 200 via the second gas channel 4b. By forming a hydrogen-based plasma in the processing space 200, a deposition process can be carried out in which the copper layer adsorbed in the adsorption process is formed as a copper film 110. In this case, the copper film 110 can also be formed by an atomic layer deposition method.

[0043] Step (S20) involves injecting a mixed gas containing hydrogen-containing gas and nitrogen-containing gas onto the substrate 100. Step (S20) can be performed by the injection unit 4 injecting the mixed gas into the processing space 200. In this case, the injection unit 4 can inject the mixed gas through the third gas flow path 4c.

[0044] d) Step (S20) allows for the continuous injection of the mixed gas while steps a) to c) (S11, S12, S13) are being performed. The mixed gas can weaken the tendency of copper particles to cling to each other by rapidly decomposing the ligands of copper organic materials (organocouple compounds). Since the mixed gas is continuously injected through step d) (S20) while steps a) to c) (S11, S12, S13) are being performed, the mixed gas can continuously weaken the tendency of copper particles to cling to each other while steps a) to c) (S11, S12, S13) are being performed. Therefore, the copper film formation method according to the present invention can resolve the problem of copper aggregation in the process of forming the copper film 110. Therefore, the copper film formation method according to the present invention can improve the film quality of the copper film 110 by improving the morphology of the copper film 110 and forming the copper film 110 to be continuously connected. Furthermore, the copper film formation method according to the present invention can increase the growth rate per cycle for forming the copper film 110, thereby shortening the process time required for forming the copper film 110.

[0045] d) In step (S20), the nitrogen-containing gas may include at least one of nitrogen (N2), ammonia (NH3), plasma-activated nitrogen (N2), and plasma-activated ammonia (NH3). In this case, step d) (S20) can be performed under a nitrogen and hydrogen atmosphere, as can steps a) to c) (S11, S12, S13). Furthermore, step d) (S20) can weaken the tendency of copper molecules to cling to each other by rapidly decomposing the ligands of the copper organism using the plasma density of nitrogen and hydrogen.

[0046] On the other hand, while steps a) (S11) and b) (S12) are being carried out, a mixed gas is continuously injected into the processing space 200 through step d) (S20), allowing a copper layer containing copper to be adsorbed using the copper-containing precursor and the mixed gas. Subsequently, a plasma using hydrogen is formed through step c) (S13), and the mixed gas is continuously injected into the processing space 200 through step d) (S20), allowing the remaining substances after removing copper from the copper layer through a reduction process, etc., to form a copper film 110 with a higher proportion of copper. Therefore, the copper film formation method according to the present invention can further improve the film quality of the copper film 110. In this case, the copper film 110 can also be formed to consist only of copper.

[0047] On the other hand, step d) (S20) can also be performed by injecting a mixed gas containing only hydrogen gas without nitrogen gas. In this case, compared to a comparative example in which the mixed gas is injected intermittently to periodically, the copper film formation method according to the present invention can increase the growth rate per cycle (GPC) for forming the copper film 110 by more than double by continuously injecting the mixed gas.

[0048] Referring to Figures 1 to 6, the copper film formation method according to the present invention can be implemented by repeating a cycle of sequentially performing steps a) (S11) and b) (S12) N times (N is a natural number greater than 1), and then performing step c) (S13). By sequentially repeating steps a) (S11) and b) (S12), the copper film formation method according to the present invention can increase the supply amount of copper-containing precursor before step c) (S13) is performed, thereby reducing the empty space within the copper layer. Therefore, the copper film formation method according to the present invention can further improve the film quality of the copper film 110 by further improving the morphology of the copper film 110. Figure 6 illustrates a case where step c) (S13) is performed after repeating a cycle of sequentially performing steps a) (S11) and b) (S12) twice, but is not limited to this, and step c) (S13) can also be performed after repeating a cycle of sequentially performing steps a) (S11) and b) (S12) four or more times. In this case, the cycle of sequentially performing steps a) (S11) and b) (S12) can be repeated six times or less. On the other hand, even while the cycle of sequentially performing steps a) (S11) and b) (S12) is being performed, the mixed gas can be continuously injected into the processing space 200 by step d) (S20).

[0049] The copper film formation method according to the present invention can also be implemented by repeating a cycle of sequentially performing steps a) (S11), b) (S12), and c) (S13) M times (where M is a natural number greater than 1). Even while the cycle of sequentially performing steps a) (S11), b) (S12), and c) (S13) is being performed, the mixed gas can be continuously injected into the processing space 200 by step d) (S20). Therefore, the copper film formation method according to the present invention can form a thick copper film 110 with a high proportion of copper. In this case, the copper film 110 can also be formed to consist only of copper.

[0050] In the copper film formation method according to the present invention, steps a) to d) (S11, S12, S13, S20) can be performed when the internal temperature of the chamber 2 is between 50°C and 300°C. The internal temperature of the chamber 2 can refer to the temperature of the processing space 200. When the internal temperature of the chamber 2 is between 50°C and 300°C, the property of copper to intertwine with each other is strengthened. However, the copper film formation method according to the present invention can weaken this property of copper to intertwine with each other through step d) (S20), so it is possible to form a copper film 110 having a film quality formed when the internal temperature of the chamber 2 is between 50°C and 300°C. Therefore, the copper film formation method according to the present invention can improve versatility by enabling the formation of a copper film 110 at various process temperatures.

[0051] Referring to Figures 1 to 7, the copper film formation method according to the present invention may include a treatment step (S30).

[0052] The treatment step (S30) can be performed by treating the substrate 100 with a plasma using hydrogen (H2) or oxygen (O2). The treatment step (S30) can be performed before step (S11). This allows the process to proceed from step (S11) after the treatment step (S30). Therefore, the copper film formation method according to the present invention is implemented to form a copper film 110 on a substrate 100 from which impurities have been removed by treatment, thereby increasing the deposition rate of the copper film 110 and improving the film quality of the copper film 110. When a lower film is placed between the substrate 100 and the copper film 110, the treatment step (S30) can be performed by treating the lower film with a plasma using hydrogen or oxygen. In this case, impurities can be removed from the lower film. The lower film may be a metal film, an oxide film, a nitride film, etc.

[0053] Referring to Figures 1 to 7, the copper film formation method according to the present invention may include step (S14) e).

[0054] Step (S14) is to inject a second purge gas onto the substrate 100. Step (S14) can be performed after step (S13) has been completed. Step (S14) can be performed by the injection unit 4 injecting the second purge gas into the processing space 200. In this case, the injection unit 4 can inject the second purge gas through at least one of the first gas flow path 4a and the second gas flow path 4b. The second purge gas may be an inert gas such as argon. Step (S14) can be used to perform a purging step to purge gases not used in the deposition process, substances removed from the copper layer, etc., from the processing space 200.

[0055] The copper film formation method according to the present invention can be implemented by repeating a cycle of sequentially performing steps a) (S11), b) (S12), c) (S13), and e) (S14) R times (R is a natural number greater than 1). While the cycle of sequentially performing steps a) (S11), b) (S12), c) (S13), and e) (S14) is repeated, step d) (S20) can continuously inject the mixed gas. Therefore, the copper film formation method according to the present invention can form a thick copper film 110 with a high proportion of copper. In this case, the copper film 110 can also be formed to consist only of copper.

[0056] The present invention described above is not limited to the embodiments and accompanying figures, and it will be apparent to those with ordinary skill in the art to which the present invention pertains that various substitutions, modifications, and changes are possible without departing from the technical spirit of the present invention.

Claims

1. A method for forming a copper film on a substrate inside a chamber, a) A step of spraying a copper-containing precursor onto the substrate, b) A step of injecting a first purge gas onto the substrate, c) Hydrogen (H) on the substrate ２ The process of forming plasma using ) and d) A step of injecting a mixed gas containing a hydrogen-containing gas and a nitrogen-containing gas onto the substrate, A method for forming a copper film, characterized in that step d) involves continuously injecting the mixed gas while steps a) to c) are performed.

2. The copper film forming method according to claim 1, characterized in that step c) is performed after the cycle of sequentially performing steps a) and b) is repeated N times (where N is a natural number greater than 1).

3. The copper film forming method according to claim 1, characterized in that the cycle of sequentially performing step a), step b), and step c) is repeated M times (where M is a natural number greater than 1).

4. The nitrogen-containing gas is nitrogen (N ２ ), ammonia (NH ３ ), nitrogen (N) activated by plasma ２ ), and ammonia (NH) activated by plasma ３ The copper film forming method according to claim 1, characterized by comprising at least one of the following.

5. Before step a) is performed, hydrogen or oxygen (O) is placed on the substrate. ２ A method for forming a copper film according to claim 1, characterized by including a step of performing treatment with plasma using ).

6. The copper film forming method according to claim 1, characterized in that steps a) to d) are performed while the internal temperature of the chamber is 50°C or higher and 300°C or lower.

7. e) The process includes the step of injecting a second purge gas onto the substrate, The copper film forming method according to claim 1, characterized in that step e) is performed after step c) has been performed.

8. The cycle of performing steps a), b), c), and e) sequentially is repeated R times (where R is a natural number greater than 1). The copper film forming method according to claim 7, characterized in that step d) involves continuously injecting the mixed gas while the cycle is repeated.

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