Patent Application
20210301402
The present disclosure relates to a film forming apparatus and a film forming method.
When a film is formed on a substrate, the substrate may warp due to the stress of the film. Therefore, for example, in Patent Document 1, provided is a plasma CVD apparatus, in which a reaction chamber on the front surface side and a reaction chamber on the rear surface side of a sample are formed, and homogeneous films are formed on both the front and rear surfaces of the sample, whereby it is possible to prevent warpage and cracking of the sample after the film formation.
Patent Document 1: Japanese Laid-Open Patent Publication No. 2003-27242
The present disclosure provides a technique capable of compensating for warpage of a substrate.
According to one embodiment of the present disclosure, there is provided a film forming apparatus including: a processing container; a support mechanism configured to support a substrate to be capable of being raised and lowered; a first gas supplier configured to supply a first gas to a front surface of the substrate supported on the support mechanism; a second gas supplier configured to supply a second gas to a rear surface of the substrate supported on the support mechanism; and a third gas supplier configured to supply a third gas to at least one of the front surface and the rear surface of the substrate supported on the support mechanism.
According to an embodiment of the present disclosure, it is possible to compensate for warpage of a substrate.
Hereinafter, exemplary embodiments for executing the present disclosure will be described with reference to drawings. In the specification and drawings, constituent elements that are substantially the same will be denoted by the same reference numerals, and redundant descriptions will be omitted.
In, for example, a process of forming multiple layers of films on a wafer in multiple layers, when the films are formed on the front surface of the wafer, the wafer may warp due to the stress of the films. As an example, when a wafer is placed on a stage that has become hot in a step after formation of an SiO2 film and an SiN film in a 3D NAND process, a Si substrate on the rear surface of the wafer may expand due to heat, and the front surface of the wafer may warp in a concave shape. The warpage of the wafer may have an effect that makes a process difficult in a step subsequent to the film formation.
Conventionally, there is a method of forming a film on the rear surface of a wafer as a method of suppressing the warpage of a wafer. However, when forming a film on the rear surface of the wafer, the gas may wrap around to the front surface and a film may be formed on the front surface of the wafer. In addition, when the wafer is heated by the radiation of a heater, the heating rate of the wafer may be slowed down. In particular, when a film is formed on the rear surface of a wafer, a device structure is formed on the front surface. Thus, since the front surface side of the wafer cannot be placed on the stage, it takes time to raise the temperature of the wafer.
Therefore, the film forming apparatus and the film forming method according to an embodiment described below compensate for the warpage of a wafer by forming a stress-adjusted film on the rear surface of the wafer. The problem in which when a film is formed on the rear surface of a wafer, a film is formed on the front surface of the wafer due to the gas wrapping around the front surface of the wafer, and the problem in which the temperature rise rate of the wafer is low are solved by supplying heated He purge gas to the surface on the side on which no film is formed. In addition, a mechanism for forming a film while switching between the front surface and the rear surface of the wafer is provided in a single processing container. As a result, in the film forming apparatus according to an embodiment, a composite process in which different types of films are alternately formed can be executed. For example, in a process of forming a film A and a film B, if the stress of the film A is too high, there is a risk that the warpage of the wafer adversely affects the result of the process when the film B is formed. At this time, if a film that compensates for stress can be formed on the rear surface immediately after the film A is formed, the film B can be stably formed.
[Configuration of Film Forming Apparatus]
First, the configuration of a film forming apparatus 1 according to an embodiment of the present disclosure will be described with reference to
The film forming apparatus 1 has a processing container 11, which is a vacuum container in which a film forming process is performed on a wafer W. On the side wall surface of the processing container 11, a carry-in/out port 13 for carrying in and out a wafer W therethrough and a gate valve 14 configured to open/close the carry-in/out port 13 are installed.
A gas shower head SH1 is formed on the ceiling of the processing container 11. In a recess 12 formed in the bottom portion of the processing container 11, a stage 3a in which a gas shower head SH2 is formed is accommodated to face the gas shower head SH1. A support mechanism 3 has a plurality of lifter pins 2 that penetrate the stage 3a and support a wafer W to be capable of being raised and lowered. In the present embodiment, as illustrated in
After the lifter pins 2 are lifted up at the initial position illustrated in
A screw hole 2d is formed below each lifter pin 2, and a protrusion 80a at the tip of each jig 80 is inserted into the screw hole 2d. A rotation mechanism 82 and a lifting mechanism 83 illustrated in
The rotation mechanism 82 and the lifting mechanism 83 illustrated in
The portion where the support 81 penetrates the bottom portion of the processing container 11 is sealed with a magnetic seal 86. The magnetic seals 85 and 86 shield the inside of the processing container 11 from the outside of the processing container 11 so as to maintain the vacuum state inside the processing container 11.
Inside the processing container 11, an exhaust groove 31 having a rectangular cross section is formed at one end side in the lengthwise direction (the left-right direction of the paper surface). In the lengthwise direction of the processing container 11, one end side at which the exhaust groove 31 is arranged is also referred to as a “downstream side”, and the side opposite the side at which the exhaust groove 31 is arranged is also referred to as an “upstream side”.
The exhaust groove 31 is open to the bottom surface of the processing container 11. A lid 32 is installed at the opening of the exhaust groove 31. As illustrated in
A film formation gas ejection part 4 is installed at the upstream side in the processing container 11. As illustrated in
Returning back to
A DCS supply source 43 configured to supply DCS (dichlorosilane) (hereinafter, referred to as “DCS”), which is an example of raw material gas, is connected to the raw material gas supply pipe 42, and the raw material gas supply pipe 42 is provided with a flow rate adjustment part 45 configured to adjust the flow rate of the DCS gas and a valve 44 configured to turn on/off the supply of DCS gas.
An NH3 supply source 47 configured to supply NH3, which is an example of the reaction gas, is connected to the reaction gas supply pipe 46, and the reaction gas supply pipe 46 is provided with a flow rate adjustment part 49 configured to adjust the flow rate of the NH3 gas and a valve 48 configured to turn on/off the supply of the NH3 gas. In this example, the raw material gas and the reaction gas are also referred to as “film formation gases”. DCS and NH3 are examples of the third gas.
An Ar gas supply source 61 configured to supply Ar gas, which is an example of replacement gas (purge gas), is connected to the replacement gas supply pipe 60, and the replacement gas supply pipe 60 is provided with a flow rate adjustment part 63 configured to adjust the flow rate of Ar gas and a valve 62 configured to turn on/off the supply of Ar gas.
The third gas supply source GS3, the film formation gas ejection part 4, and the gas supply pipe 40 are an example of the third gas supplier, which supplies the third gas to at least one of the front surface or the rear surface of the wafer W supported by the support mechanism 3. Here, the third gas supplier supplies the third gas in the radial direction of the wafer W supported by the support mechanism 3.
A remote plasma generator 65 is connected to the gas supply pipe 40. The remote plasma generator 65 supplies plasma from the side wall of the processing container 11. Switching between the supply of the third gas from the third gas supply source GS3 and the supply of plasma from the remote plasma generator 65 is performed by controlling the valves 44 and 48 in the third gas supply source GS3 and the remote plasma generator 65 in the third gas supply source GS3.
A gas shower head SH1 is installed on the ceiling of the processing container 11, and a first gas supply source GS1 configured to supply a concentration adjustment gas for adjusting the concentration of the film formation gas, for example, Ar gas, which is a dilution gas, or heated He gas is connected to the gas shower head SH1 through a gas supply pipe 52.
The first gas supply source GS1 (first gas supplier) is divided into two systems, each of which is provided with a flow rate adjustment part 53 and a valve 54. The flow rate adjustment part 53 and the valve 54 are also referred to as a “gas adjustment part” 55. A He gas supply source 57 is connected to one gas adjustment part 55, and an Ar gas supply source 58 is connected to the other gas adjustment part 55. A heater 56 heats the He gas supplied from the He gas supply source 57. The heated He gas and the Ar gas supplied from the Ar gas supply source 58 are switched by the control of the valve 54, are supplied to the gas shower head SH1, and are introduced into the processing container 11 from a plurality of gas holes 50 via a buffer chamber 51. The He gas functions as a purge gas that prevents the film formation gas introducing into the front surface of the wafer W. In addition, the Ar gas functions as a dilution gas for the film formation gas.
The plurality of gas holes 50 is formed in the lengthwise direction from the upstream side to the downstream side of the gas flow of the film formation gas such as DCS supplied from the side wall of the processing container 11, and are formed in a slit shape or a hole shape extending in the widthwise direction so as to cover the entire surface of the wafer W when viewed in a plane. As a result, Ar gas, which is a diluting gas, or heated He gas is supplied from each gas hole 50 towards the front surface of the wafer W supported by the support mechanism 3 in the state in which the flow rate is uniform in the widthwise direction.
He gas is an example of the first gas. The first gas supply source GS1 and the gas shower head SH1 are an example of the first gas supplier configured to supply the first gas to the front surface of the wafer W supported on the support mechanism 3. The first gas is not limited to He gas, and an inert gas may be heated and supplied as the first gas. Further, the dilution gas supplied from the gas shower head SH1 is not limited to Ar gas, and may be an inert gas such as N2 gas.
When a film is formed the rear surface of the wafer W, the support mechanism 3 brings the wafer W close to the first gas supplier (e.g., the position PA in
The gas shower head SH2 supplies a concentration adjustment gas for adjusting the concentration of the film formation gas, for example, Ar gas, which is a dilution gas, or heated He gas. A gas supply pipe 72 is connected to the gas shower head SH2, and a second gas supply source GS2 configured to supply a second gas is connected to the gas supply pipe 72.
The second gas supply source GS2 (second gas supplier) is divided into two systems, each of which is provided with a flow rate adjustment part 73 and a valve 74. The flow rate adjustment part 73 and the valve 74 are also referred to as a “gas adjustment part” 75. A He gas supply source 77 is connected to one gas adjustment part 75, and an Ar gas supply source 78 is connected to the other gas adjustment part 75. A heater 76 heats the He gas supplied from the He gas supply source 77. The heated He gas and the Ar gas supplied from the Ar gas supply source 78 are switched by the control of the valve 74, are supplied to the gas shower head SH2, and are introduced into the processing container 11 from a plurality of gas holes 70 via a buffer chamber 71. The He gas functions as a purge gas that prevents the film formation gas from introducing to the rear surface of the wafer W. In addition, the Ar gas functions as a dilution gas for the film formation gas.
The plurality of gas holes 70 is formed in the lengthwise direction from the upstream side to the downstream side of the gas flow of the film formation gas supplied from the side wall of the processing container 11, and are formed in a slit shape or a hole shape extending in the widthwise direction so as to cover the entire surface of the wafer W when viewed in a plane. As a result, Ar gas, which is a diluting gas, or heated He gas is supplied from each gas hole 70 towards the rear surface of the wafer W supported by the support mechanism 3 in the state in which the flow rate is uniform in the widthwise direction.
He gas is an example of the second gas. The second gas supply source GS2 and the gas shower head SH2 are an example of the second gas supplier configured to supply the second gas to the rear surface of the wafer supported on the support mechanism 3. The second gas is not limited to He gas, and an inert gas may be heated and supplied as the second gas. Further, the dilution gas supplied from the gas shower head SH2 is not limited to Ar gas, and may be an inert gas such as N2 gas.
When a film is formed the front surface of the wafer W, the support mechanism 3 brings the wafer W close to the second gas supplier (e.g., the position PB in
That is, when the film formation gas is supplied and a film forming process is performed on the front surface of the wafer W, the support mechanism 3 lowers the wafer W so as to bring the wafer W close to the second gas supplier, as illustrated in
Meanwhile, when a film forming process is performed on the rear surface of the wafer W, the support mechanism 3 raises the wafer W so as to bring the wafer W close to the first gas supplier, as illustrated in
The film forming process in the film forming apparatus 1 having the configuration described above will be briefly described. First, the gate valve 14 is opened, and a wafer W, which is carried in from the outside by a transport arm, is held by the support mechanism 3. After the gate valve 14 is closed and the processing container 11 is sealed, the supply of Ar gas is started from the film formation gas ejection part 4, and exhaust is performed from the exhaust groove 31 so as to adjust the internal pressure of the processing container 11. Next, the support mechanism 3 is raised/lowered to a position at which the film forming process is performed on the front surface of the wafer W.
Thereafter, a film forming process is performed on the front surface of the wafer through the ALD method using DCS, which is a raw material gas, and NH3, which is a reaction gas as a film formation gas. A method of supplying these film formation gases to the wafer W will be described. The supply of the film formation gas towards the wafer W gripped by the support mechanism 3 is started in the state in which the exhaust is being exhausted from the exhaust groove 31, and the dilution gas is supplied from the gas shower head SH1 towards the front surface of the wafer W. The film formation gas flows from the gas supply pipe 40 into the film formation gas ejection part 4, and the film formation gas diffuses uniformly in the film formation gas ejection part 4. Thereafter, the film formation gas is supplied from the slit 41 of the film formation gas ejection part 4 at a uniform flow rate in the widthwise direction of the wafer W, and flows along the front surface of the wafer W over the entire surface. Thereafter, the film formation gas flows into the exhaust groove 31 while maintaining a parallel flow, and is exhausted from the exhaust pipe 34.
The concentration of the film formation gas is diluted at the most upstream position B where the film formation gas flowing on the front surface of the wafer W and the dilution gas join. The diluted film formation gas is further diluted at the position C where it then joins with the diluted gas, and then flows downstream while being diluted at positions D, E, and F, in this order.
Therefore, the concentration (concentration of the raw material gas or the reaction gas) of the film formation gas becomes lower as it is located on the downstream side, for example, as illustrated in
Then, the rotation mechanism 82 is driven so as to rotate the wafer W around the axis of the support 81, which supports the stage 3a in
Referring back to
In addition, a recipe representing these programs and processing conditions may be stored in a hard disc or semiconductor memory. In addition, the recipe may be set at a predetermined position to be read out in the state of being stored in a storage medium readable by a portable computer, such as a CD-ROM or a DVD.
[Switching Between Film Formation on Front Surface and Film Formation on Rear Surface of Wafer]
Switching between the film formation on the front surface and the film formation on the rear surface of a wafer W will be described with reference to
When forming a film on the front surface of the wafer W, the film formation is performed in the state in which the wafer W is brought close to the second gas supplier GS2, as illustrated in
When a film is formed on the rear surface of the wafer W, the film formation is performed in the state in which the wafer W is brought close to the first gas supplier GS1, as illustrated in
[When Forming Film on Front Surface of Wafer W]
Specifically, when forming a film on the front surface of the wafer W, as illustrated in
In this case, the controller 100 opens the valve 74 connected to the He gas supply source 77 of the second gas supply source GS2 illustrated in
In the plasma process, plasma is generated not only in the space between the wafer W and the shower head SH1, but also in the space between the wafer W and the shower head SH2, which causes film formation on the rear surface of the wafer W. In contrast, in the present embodiment, while a film is formed on the front surface of the wafer W, heated He gas is introduced from the shower head SH2 and is sprayed onto the rear surface of the wafer W. As a result, the film formation gas is suppressed from being introduced to the rear surface of the wafer W, and the film formation on the rear surface of the wafer W is prevented.
In addition, the introduction of the He gas reduces the electron density of plasma in this space, which has the effect of suppressing the ignition of plasma. As a result, plasma generation in the space between the wafer W and the shower head SH2 can be suppressed by a mechanism for purging the heated He gas from the shower head SH2, and film formation on the rear surface of the wafer W can be prevented.
In the film forming process, a predetermined film formation is performed on the front surface of the wafer W using the supplied raw material gas for film formation. In this case, the controller 100 closes the valve 54 connected to the He gas supply source 57 of the first gas supply source GS1 illustrated in
Next, the controller 100 closes the valve 44 to stop the supply of the raw material gas and emits the plasma of NH3 gas from the remote plasma generator 65 so as to fix the raw material gas on the front surface of the wafer W. Here, the controller 100 controls the switching between the raw material gas and the plasma, but the present disclosure is not limited thereto, and may control the switching between the raw material gas, the reaction gas and the plasma. In addition, while switching between the raw material gas and the plasma, Ar gas may be supplied from the Ar gas supply source 61 to purge the interior of the processing container 11.
[When Forming Film on Rear Surface of Wafer W]
In addition, when forming a film on the rear surface of the wafer W, as illustrated in
In this case, the controller 100 opens the valve 54 connected to the He gas supply source 57 of the first gas supply source GS1 illustrated in
In addition, by introducing He gas into the space between the wafer W and the shower head SH1, the ignition of plasma can be suppressed, plasma generation in the space between the wafer W and the shower head SH1 can be suppressed, and thus film formation on the rear surface of the wafer W can be prevented.
In this case, when a predetermined film formation is performed on the rear surface of the wafer W using the supplied raw material gas for film formation, the controller 100 closes the valve 74 connected to the He gas supply source 77 of the second gas supply source GS2 illustrated in
The controller 100 may close the valve 44 to stop the supply of the raw material gas and may emit plasma from the remote plasma generator 65 so as to fix the raw material gas on the front surface of the wafer W. Further, the controller 100 may control switching between the raw material gas, the reaction gas and the plasma. Ar gas may be supplied from the Ar gas supply source 61 at a predetermined timing to purge the interior of the processing container 11.
As described above, in the film forming apparatus 1 according to the present embodiment, heated He gas is supplied from the shower heads SH1 and SH2 to heat the wafer W while purging the surface of the wafer W on the side where film formation is not performed. As a result, it is possible to prevent a film from being formed on the surface of the wafer W on which it is not intended to perform film formation, and it is possible to raise the temperature of the wafer W at a high speed with this configuration in which the wafer W is not in contact with the heater. In this case, although the film formation temperature is about 100 degrees C. to 500 degrees C., it is necessary to raise the temperature of the gas 800 degrees C. before the gas is released into the vacuum space in consideration of the large heat loss due to expansion when the heated He gas is released into the vacuum space. Regarding this, it is possible to raise the temperature of the gas to 800 degrees C. using a high temperature gas heater.
When film formation is performed on the front surface of the wafer W, the distance between the wafer W and the shower head SH2 is set to be as narrow as possible. When film formation is performed on the rear surface of the wafer W, the distance between the wafer W and the shower head SH1 is set to be as narrow as possible. As a result, the He gas leaks only from the outer peripheries of the shower heads SH1 and SH2, and it is possible to make it difficult for the film forming gas to enter the surface of the wafer W on the side where film formation is not performed.
When forming a film on the rear surface of the wafer W, as illustrated in
When forming a film on the front surface of the wafer W, the third gas supplier GS3 switches between the supply of the side flow precursor (the raw gas of film formation) and the supply of the plasma supplied from the remote plasma generator 65, so as to supply the plasma after supplying the precursor in the radial direction of the wafer W supported on the support mechanism 3. In addition, heated He gas is supplied from the shower head SH2 to heat the wafer W. In addition, a dilution gas such as Ar gas is introduced from the shower head SH1 so as to adjust a film formation concentration.
In this configuration, since it becomes possible to supply the side flow raw material gas and plasma from the side wall of the film forming apparatus 1, it becomes possible to switch between the film formation on the front surface and the film formation on the rear surface of the wafer W. This makes it possible to compensate for the warpage of the wafer W caused due to the stress of the film.
In the film forming apparatus 1 according to an embodiment, the first gas supply source GS1 and the second gas supply source GS2 are installed, but they may be integrated. For example, when the second gas supply source GS2 is eliminated, the first gas supply source GS1 is connected to both the gas shower heads SH1 and SH2. Then, when forming a film on the front surface of the wafer, the valves 54 are controlled so as to supply a dilution gas to the gas shower head SH1 and to supply heated He gas to the gas shower head SH2. When forming a film on the rear surface of the wafer, the valves 54 are controlled so as to supply dilution gas to the gas shower head SH2 and to supply heated He gas to the gas shower head SH1. Of course, as a premise, the position of the wafer W is controlled by the support mechanism 3 so as to approach the first gas supplier GS1 or the second gas supplier GS2 depending to the surface on which a film is formed. As a result, the first gas supply source GS1 or the second gas supply source GS2 may be integrated so as to simplify the configuration of the film forming apparatus 1.
Instead of the support mechanism 3 or in addition to the support mechanism 3, a grip part configured to grip and hold the edge of the wafer W may be provided, and the grip part may be rotatable using a rotary transport arm for the grip part. Since the front surface and the rear surface of the wafer W can be inverted by rotation, it is possible to form a film on the front side and the rear surface of the wafer. This makes it possible to use the processing container 11 without significant change of the existing processing container 11.
The wafer W may be reversed outside the processing container 11. For example, an aligner for positioning a wafer W may be provided with a rotation mechanism for reversing the wafer W. After reversing the wafer W, the wafer W may be returned to the interior of the processing container 11 so as to form a film on the rear surface of the wafer W. In this case, by providing the rotation mechanism outside the processing container 11, it is not necessary to change the configuration inside the processing container 11, so that the film forming apparatus 1 can be easily introduced.
The raw material gas and the reaction gas may be supplied from the shower head SH1. In this case, the DCS supply source 43 configured to supply DCS, which is an example of the raw material gas, and respective parts (the valve 44 and the flow rate adjustment part 45) may be connected to the gas supply pipe 52. Similarly, the NH3 supply source 47 configured to supply NH3, which is an example of the reaction gas, and respective parts (the valve 48 and flow rate adjusting part 49) may be connected to the gas supply pipe 52. In this case, the DCS supply source 43, the valve 44, the flow rate adjustment part 45, the NH3 supply source 47, the valve 48, and the flow rate adjustment part 49 are an example of the third gas supplier configured to supply the third gas to at least one of the front surface and the rear surface of the wafer W supported on the support mechanism 3.
When forming a film on the front surface of the wafer W while supplying a raw material gas and a reaction gas from the shower head SH1, the wafer W is brought close to the shower head SH2 (e.g., the position PB in
When forming a film on the rear surface of the wafer W, the support mechanism 3 raises the wafer W so as to bring the wafer W close to the first gas supplier (e.g., the position PA in
As described above, with the film forming apparatus 1 of the present embodiment, it is possible to form a film on the front surface and the back surface of the wafer, and it is possible to compensate for the warpage of a wafer caused due to a film.
It should be considered that the film forming apparatus and the film forming method according to the embodiments disclosed herein are illustrative and not restrictive in all aspects. The above embodiments may be modified and improved in various forms without departing from the scope and spirit of the appended claims. The matters described in the above embodiment may take other configurations without contradiction, and may be combined without contradiction.
The processing apparatus of the present disclosure is applicable to any of a capacitively coupled plasma (CCP) type, an inductively coupled plasma (ICP) type, a radial line slot antenna (RLSA) type, an electron cyclotron resonance plasma (ECR) type, and a helicon wave plasma (HWP) type.
In this specification, a wafer W has been described as an example of a substrate. However, the substrate is not limited thereto, and may be any of various substrates used for a flat panel display (FPD), a printed circuit board, or the like.
The present international application claims priority based on Japanese Patent Application No. 2018-150525 filed on Aug. 9, 2018, the disclosure of which are incorporated herein in its entirety by reference.
1: film forming apparatus, 2: lifter pin, 3: support mechanism, 3a: stage, 11: processing container, 50: gas hole, 51: buffer chamber, 65: remote plasma generator, 70: gas hole, 71: buffer chamber, 80: jig, 81: support, 82: rotation mechanism, 83: lifting mechanism, 85, 86: magnetic seal, 100: controller, GS1: first gas supply source, GS2: second gas supply source, GS3: third gas supply source, SH1: gas shower head, SH2: gas shower head
| Number | Date | Country | Kind |
|---|---|---|---|
| 2018-150525 | Aug 2018 | JP | national |
This is a National Phase Application filed under 35 U.S.C. 371 as a national stage of PCT/JP2019/029697, filed Jul. 29, 2019, an application claiming the benefit of Japanese Application No. 2018-150525, filed Aug. 9, 2018, the content of each of which is hereby incorporated by reference in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2019/029697 | 7/29/2019 | WO | 00 |
