Patent Application
20240304436
The present disclosure relates to a substrate processing method and a substrate processing apparatus.
For example, use of a hard mask containing carbon as an etching mask is known.
Patent Document 1 discloses a method of forming an amorphous carbon layer, which includes depositing an amorphous carbon layer on a base layer, patterning the amorphous carbon layer, etching at least a portion of the amorphous carbon layer, implanting a dopant into the amorphous carbon layer by a tilt process; and etching the base layer.
In an aspect, the present disclosure provides a substrate processing method and a substrate processing apparatus that improve an etching resistance and suppress a film stress.
In order to solve the above-mentioned problem, an embodiment of the present disclosure provides a substrate processing method of forming a carbon-based film on a substrate, the method including: a process of placing the substrate on a stage; a first film forming process of forming a first carbon-based film having a first stress; a second film forming process of forming a second carbon-based film having a second stress; and a third film forming process of repeating the first film forming process and the second film forming process to form a stacked body of the first carbon-based film and the second carbon-based film, wherein the first stress and the second stress are oriented in the same direction, and the first stress and the second stress have different intensities.
According to the aspect, it is possible to provide a substrate processing method and a substrate processing apparatus that improve an etching resistance and suppress a film stress.
Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In each of the drawings, the same components may be denoted by the same reference numerals, and redundant descriptions thereof may be omitted.
A substrate processing apparatus 1 according to an embodiment will be described with reference to
The substrate processing apparatus 1 includes the substantially cylindrical airtight processing container 2. An exhaust chamber 21 is provided in a central portion of a bottom wall of the processing container 2.
The exhaust chamber 21 has, for example, a substantially cylindrical shape that protrudes downward. An exhaust flow path 22 is connected to the exhaust chamber 21, for example, on a side surface of the exhaust chamber 21. An exhauster 24 is connected to the exhaust flow path 22 via a pressure adjuster 23. The pressure adjuster 23 includes, for example, a pressure adjustment valve such as a butterfly valve. The exhaust flow path 22 is configured such that a pressure inside the processing chamber 2 can be reduced by the exhauster 24. A transfer port 25 is provided in a side surface of the processing container 2. The transfer port 25 is configured to be openable and closable by a gate valve 26. Loading/unloading of the substrate W between an interior of the processing container 2 and a transfer chamber (not illustrated) is performed via the transfer port 25.
A stage 3 configured to substantially hold the substrate W horizontally is provided in the processing container 2. The stage 3 has a substantially circular shape in plan view and is supported by a support 31. A substantially circular recess 32 is formed in a surface of the stage 3 to place therein the substrate W having a diameter of, for example, 300 mm. The recess 32 has an inner diameter slightly larger than the diameter of the substrate W (e.g., by about 1 mm to 4 mm). A depth of the recess 32 is substantially the same as, for example, a thickness of the substrate W. The stage 3 is made of a ceramic material such as aluminum nitride (AlN). In addition, the stage 3 may be made of a metallic material such as nickel (Ni). Instead of the recess 32, a guide ring configured to guide the substrate W may be provided at a peripheral edge of the surface of the stage 3.
A lower electrode 33 is embedded in the stage 3. A temperature adjustment mechanism 34 is embedded below the lower electrode 33. The temperature adjustment mechanism 34 adjusts a temperature of the substrate W mounted on the stage 3 to a set temperature based on a control signal from a controller 9. When the entire stage 3 is made of metal, the entire stage 3 functions as a lower electrode. Thus, it is unnecessary to embed the lower electrode 33 in the stage 3.
An RF power supply 35 is connected to the lower electrode 33 via a matcher 351. The RF power supply 35 applies low-frequency (LF) power having a frequency lower than that of an RF power supply 51, which will be described later, to the lower electrode 33. The high-frequency power generated by the RF power supply 35 is used as radio frequency power for bias that attracts ions to the substrate W. A frequency of the RF power supply 35 is, for example, 13.56 MHz.
The stage 3 is provided with a plurality of (for example, three) lifting pins 41 configured to hold and vertically move the substrate W placed on the stage 3. A material of the lifting pins 41 may be, for example, ceramic, such as alumina (Al2O3) or quartz. Lower ends of the lifting pins 41 are installed on a support plate 42. The support plate 42 is connected to a lifting mechanism 44 provided outside the processing container 2 via a lifting shaft 43.
The lifting mechanism 44 is installed, for example, below the exhaust chamber 21. A bellows 45 is provided between the lifting mechanism 44 and an opening 211 for the lifting shaft 43 formed in a lower surface of the exhaust chamber 21. The support plate 42 may have a shape that can be move vertically without interfering with the support 31 of the stage 3. The lifting pins 41 are configured to be move vertically between above the surface of the stage 3 and below the surface of the stage 3 by the lifting mechanism 44. In other words, the lifting pins 41 are configured to be capable of protruding from a top surface of the stage 3.
In addition, a lower end portion of the support 31 passes through the opening 212 in the exhaust chamber 21 and is supported by a lifting mechanism 46 via a lifting plate 47 disposed below the processing container 2. A bellows 48 is provided between a bottom of the exhaust chamber 21 and the lifting plate 47, and the airtightness inside the processing container 2 is maintained even by a vertical movement of the lifting plate 47.
By moving the lifting plate 47 vertically using the lifting mechanism 46, the stage 3 can be move vertically. As a result, a gap between the stage 3 and a gas supply 5 can be adjusted.
The gas supply 5 is provided on a ceiling wall 27 of the processing container 2 via an insulator 28. The gas supply 5 forms an upper electrode and faces the lower electrode 33. The RF power supply 51 is connected to the gas supply 5 via a matcher 511. The RF power supply 51 applies high-frequency power having a frequency higher than that of the RF power supply 35 to the upper electrode (the gas supply 5). The high-frequency power generated by the RF power supply 51 is used as radio frequency power for plasma generation required for film formation on the substrate W. The frequency of the RF power supply 51 is, for example, the very-high-frequency (VHF) band of 100 MHz to 300 MHz. An RF electric field is generated between the upper electrode (the gas supply 5) and the lower electrode 33 by supplying RF power from the RF power supply 51 to the upper electrode (the gas supply 5). The gas supply 5 includes a hollow gas diffusion chamber 52. In a bottom surface of the gas diffusion chamber 52, for example, a plurality of holes 53 configured to disperse and supply a processing gas into the processing container 2 is evenly arranged. A heater 54 is embedded in the gas supply 5, for example, above the gas diffusion chamber 52. The heater 54 is heated to a set temperature by being fed with power from a power supply (not illustrated) based on a control signal from the controller 9.
The gas diffusion chamber 52 is provided with a gas supply path 6. The gas supply path 6 in in communication with the gas diffusion chamber 52. A gas source 61 is connected to an upstream side of the gas supply path 6 via a gas line 62. The gas source 61 includes, for example, various processing gas sources, mass flow controllers, and valves (none of which are illustrated). Various processing gases include film forming gases containing carbon atoms (e.g., CH4, C2H2, C3H6, and C2H4) used in the above-described method of forming the carbon-based film. Various processing gases may also include carrier gases (e.g., H2, Ar, He, O2, and N2). Various processing gases are introduced into the gas diffusion chamber 52 from the gas source 61 via the gas line 62.
The substrate processing apparatus 1 includes the controller 9. The controller 9 is, for example, a computer, and includes, for example, a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), and an auxiliary storage device. The CPU operates based on a program stored in the ROM or the auxiliary storage device and controls operations of the substrate processing apparatus 1. The controller 9 may be provided either inside or outside the substrate processing apparatus 1. In the case where the controller 9 is provided outside the substrate processing apparatus 1, the controller 9 is capable of controlling the substrate processing apparatus 1 via a wired or wireless communication mechanism.
Next, an example of an operation of the substrate processing apparatus 1 according to the present embodiment will be described with reference to
In step S101, the controller 9 prepares the substrate W. The controller 9 controls a transfer apparatus (not illustrate) to place the substrate W on the stage 3 of the substrate processing apparatus 1. Here, the substrate W placed on the stage 3 has a target film 210 formed on a Si substrate 200 (see
In step S102, the controller 9 forms a first film (a first carbon-based film) 221 having a first stress on the substrate W. In addition, a direction of the stress of the first film 221 (a direction of a first stress) is a compressive stress. Here, the first film 221 is a carbon film, for example, a polymer like carbon (PLC) film to be described later.
Here, the controller 9 controls the temperature adjustment mechanism 34 to set the temperature of the substrate W to be a predetermined temperature. In addition, the temperature adjustment mechanism 34 controls the pressure adjuster 23 and the exhauster 24 to set the interior of the processing container 2 to be a predetermined pressure. The controller 9 also controls the gas source 61 to supply a gas into the processing container 2. In addition, the controller 9 controls the RF power supply 51 to apply the high-frequency power (VHF) to the upper electrode (the gas supply 5). On the other hand, during the film formation of the first film 221, the RF power supply 35 does not apply the low-frequency power (LF) to the lower electrode 33.
An example of a recipe in step S102 is as follows.
In step S103, the controller 9 forms a second film (second carbon-based film) 222 having a second stress on the substrate W. In addition, a direction of the stress of the second film 222 (a direction of a second stress) is, for example, a compressive stress, which is the same as the direction of the stress of the first film 221 (the direction of the first stress). However, the stress of the first film 221 (first stress) and the stress of the second film 222 (second stress) differ from each other in intensity. Here, the second film 222 is a carbon film, such as a diamond like carbon (DLC) film to be described later.
Here, the controller 9 controls the temperature adjustment mechanism 34 to set the temperature of the substrate W to be a predetermined temperature. In addition, the temperature adjustment mechanism 34 controls the pressure adjuster 23 and the exhauster 24 to set the interior of the processing container 2 to be a predetermined pressure. The controller 9 also controls the gas source 61 to supply a gas into the processing container 2. In addition, the controller 9 controls the RF power supply 51 to apply the high-frequency power (VHF) to the upper electrode. In addition, the controller 9 controls the RF power supply 35 to apply the low-frequency power (LF) to the lower electrode.
In addition, an example of a recipe in step S103 is as follows.
In step S104, the controller 9 determines whether film formation of the first film 221 and the second film 222 on the substrate W has been repeated a predetermined number of times. When the film formation has not been repeated the predetermined number of times (step S104, “No”), the process of the controller 9 returns to step S102, and the film formation of the first film 221 (S102) and the film formation of the second film 222 (step S103) are repeated. When the film formation has been repeated the predetermined number of times (step S104, “Yes”), the process of the controller 9 ends. As a result, the stacked body 220 in which the first films 221 and the second films 222 are alternately formed on the target film 210 of the substrate W is formed.
Next, the PLC film as the first film 221 and the DLC film as the second film 222 will be further described with reference to
The DLC film is a carbon-based film having an irregular amorphous structure in which both sp3 bonds illustrated in
The PLC film is a carbon-based film having an irregular amorphous structure in which both sp3 bonds illustrated in
As illustrated in
By alternately forming the PLC film (the first film 221) having the weak compressive stress and the DLC film (the second film 222) having the strong compressive stress to form the stacked body 220, a stress of the stacked body 220 can be alleviated as compared with that in a case where a stacked body (hard mask) of carbon-based films is formed using the DLC films only.
In addition, since the stacked body 220 includes the DLC films (the second films 222) having a high dry etching resistance, a dry etching resistance of the stacked body 220 can be improved.
In addition, the lowermost film of the stacked body 220 may be the PLC film (the first film 221) having the weak compressive stress. Since the first film 221 in direct contact with the target film 210 has the weak compressive stress, adhesion between the target film 210 and the first film 221 can be enhanced. As a result, film detachment of the stacked body 220 can be prevented.
The stacked body 220 has been described as being an alternately stacked body in the order of the PLC film and the DLC film from the surface of the target film 210, but is not limited thereto. The stacked body 220 may be alternately stacked body in the order of the DLC film and the PLC film from the surface of the target film 210. The first DLC film in contact with the surface of the target film 210 may have a small film thickness. With this configuration, even when the first film 221 that is in direct contact with the target film 210 is the DLC film, the compressive stress can be suppressed and the adhesion between the target film 210 and the first film 221 can be enhanced by reducing the film thickness. As a result, film detachment of the stacked body 220 can be prevented.
In (a) of
In (b) and (c) of
In addition, an example of a recipe at the time of film formation of the measured stacked body 220 is as follows.
As illustrated in
As described above, a ratio of DLC in the stacked body 220 can be adjusted by controlling the application time of the high-frequency power and the low-frequency power (VHF+LF) with respect to the total film formation time. That is, the ratio of DLC in the stacked body 220 can be increased by increasing the ratio of the application time of the high-frequency power and the low-frequency power (VHF+LF).
Next, the compressive stress and the dry etching resistance of the stacked body 220 formed according to the time charts illustrated in (a) to (c) of
The first vertical axis on the left-hand side represents a stress. As for the stress, the direction of the compressive stress is assumed to be negative. In addition, results of the stress in the stacked body 220 formed according to the time charts illustrated in (a) to (c) of
The second vertical axis on the right-hand side represents dry etching rate (DER). In addition, results of the dry etching rate of the stacked body 220 formed according to the time charts illustrated in (a) to (c) of
The horizontal axis represents the ratio of the application time of the high-frequency power and the low-frequency power (VHF+LF) to the total film formation time. In addition, the stacked body 220 formed according to the time chart as illustrated in (c) of
As illustrated in
In addition, as the ratio of the application time of the high-frequency power and the low-frequency power (VHF+LF) to the total film formation time increases, more DLC is formed in the stacked body 220, and the dry etching rate decreases, in other words, the dry etching resistance of the stacked body 220 is improved.
As described above, with the stacked body 220 formed by the substrate processing apparatus 1 according to the present embodiment, the compressive stress can be alleviated more than the DLC film (see (d) of
For example, by setting the ratio of the application time of the high-frequency power (VHF) to the total film formation time to be 13% to 80%, both the improvement of the dry etching resistance of the stacked body 220 and the alleviation of the compressive stress of the stacked body 220 can be achieved.
In addition, the time charts for forming stacked body 220 are not limited to those illustrated in
In the example illustrated in (a) of
Although the substrate processing method by the substrate processing apparatus 1 has been described above, the present disclosure is not limited to the above-described embodiment or the like, and various modifications and improvements can be made within the scope of present disclosure described in the claims.
In addition, although it has been described that switching periods of the applied voltages in
In the present embodiment, although it has been described that a stress intensity in a formed carbon-based film is controlled by controlling the bias power (the low-frequency power (LF)), the present disclosure is not limited thereto.
For example, when forming the first film 221 and the second film 222, the gap between the stage 3 and the gas supply 5 may be changed by controlling the lifting mechanism 46. By changing the gap between the stage 3 and the gas supply 5, the ratio of sp3 bonds and sp2 bonds in the formed carbon-based film is changed. With this configuration, the DLC films and the PLC films to be alternately stacked by moving the stage 3 vertically.
The present application claims priority based on Japanese Patent Application No. 2021-26704 filed on Feb. 22, 2021, the disclosure of which is incorporated herein in its entirety by reference.
W: substrate, 1: substrate processing apparatus, 2: processing container, 3: stage, 5: gas supply (upper electrode), 6: gas supply path, 9: controller, 33: lower electrode, 35: RF power supply, 51: RF power supply, 200: Si substrate, 210: target film, 220: stacked body (hard mask), 221: first film, 222: second film
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-026704 | Feb 2021 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2022/005752 | 2/14/2022 | WO |
