JP7845145B2 - Apparatus for processing substrates, and method for processing substrates - Google Patents

Description

This disclosure relates to an apparatus for processing substrates and a method for processing substrates.

In the manufacturing process of semiconductor devices, processes such as film deposition are sometimes carried out while heating the semiconductor wafer (hereinafter referred to as "wafer"), which is the substrate to be processed.

For example, Patent Document 1 describes a technique for heating a wafer on a mounting platform to a predetermined temperature using a heater embedded in the platform, thereby forming an _SiO2 film on the surface of the wafer.

Japanese Patent Publication No. 2018-64058

This disclosure provides a technology for initiating substrate processing while reducing the effects of temperature changes associated with placing a substrate that has not yet been heated onto a mounting stage.

This disclosure relates to an apparatus for processing substrates,
A mounting platform provided inside the processing container and having a mounting surface on which the substrate is placed,
To heat different areas of the mounting surface, a plurality of heating units are provided on the mounting base described above,
Each of the aforementioned heating units is provided with a plurality of power supply units that supply power to it,
A temperature detection unit for detecting the temperature of a region where one of the plurality of heating units is provided,
The system includes a power supply control unit that controls the power supply of a plurality of power supply units, such that, based on the temperature detected by the temperature detection unit, it supplies power to one heating unit so that the detected temperature approaches a preset target temperature, and supplies power to the other heating units equal to the power supplied to the first heating unit multiplied by a preset power supply ratio.
The power supply control unit is a device that changes the power supply ratio during an initial heating period to stabilize the temperature of the substrate after the substrate is placed on the aforementioned stand, and a main heating period which includes a period during which processing of the substrate is carried out after the initial heating period has elapsed.

According to this disclosure, it is possible to start processing the substrate while reducing the effects of temperature changes that occur when placing a substrate that has not yet been heated onto the mounting stage.

This is a longitudinal cross-sectional side view of the film deposition apparatus related to this disclosure. This is a plan view showing an example of the arrangement of multiple heaters within the mounting base. This is a block diagram showing an example of a power supply mechanism for multiple heaters. This is an explanatory diagram showing an example of setting the power supply ratio to the heater in a comparative configuration. This graph shows the time-dependent changes in power supply control operation in the comparative configuration. This graph shows the film thickness distribution of films formed under power supply control in the comparative configuration. This is an explanatory diagram showing an example of setting the power supply ratio to the heater during the initial heating period in the first embodiment. This is an explanatory diagram showing an example of setting the power supply ratio to the heater during the main heating period in the first embodiment. This graph shows the change in power supply control operation over time in the first embodiment. This graph compares the change over time in the power supplied to the heater in the first embodiment and the comparative embodiment. This graph compares the time-dependent changes in temperature detection values in the first embodiment and the comparative embodiment. This graph shows the film thickness distribution of a film formed under power supply control according to the first embodiment. This is an explanatory diagram showing an example of setting the power supply ratio to the heater during the initial heating period and the main heating period in the second embodiment. This is the first explanatory diagram showing an example of setting the power supply ratio to the heater during the initial heating period in the second embodiment. This is a second explanatory diagram showing an example of setting the power supply ratio to the heater during the initial heating period in the second embodiment. This graph shows the change in power supply control operation over time in the second embodiment. This graph compares the time-dependent changes in the power supplied to the heater in the first and second embodiments and the comparative configuration. This graph compares the changes in temperature detection values over time in the first and second embodiments and the comparative form. This is a graph showing the film thickness distribution of a film formed under power supply control according to the second embodiment.

<Film forming equipment>
An embodiment of a device for depositing a film on a substrate (hereinafter referred to as the "film deposition device") will be described with reference to Figures 1 and 2. There are no particular limitations on the type of film to be deposited, but in the following embodiment, the case of forming an amorphous silicon film (a-Si film) will be used as an example.

The film deposition apparatus 1 includes a processing container 10 for housing a semiconductor wafer (hereinafter referred to as "wafer") W, which is the substrate. An inlet/outlet 11 for loading and unloading the wafer W is formed in the side wall of the processing container 10, and this inlet/outlet 11 can be opened and closed by a gate valve 12. Furthermore, an annular exhaust duct 13 is arranged on the upper part of the side wall of the processing container 10. A top wall 14 is provided on the upper surface of this exhaust duct 13 to close the upper opening of the processing container 10. The processing container 10 is connected to a vacuum exhaust section 17, which is, for example, a vacuum pump, via a vacuum exhaust passage 16 through an exhaust port 131 of the exhaust duct 13.

An APC (Auto Pressure Controller) valve 18, which forms the pressure adjustment unit, is interposed in the vacuum exhaust passage 16. The APC valve 18 is, for example, a butterfly valve and is provided to open and close the vacuum exhaust passage 16. By adjusting the opening degree of the APC valve 18, the conductance of the vacuum exhaust passage 16 can be increased or decreased, thereby adjusting the pressure inside the processing container 10.

Inside the processing container 10, a mounting table 2 is provided to horizontally support the wafer W. A heater 21, which is a heating element for heating the wafer W, is embedded inside the mounting table 2. As shown in the plan view of Figure 2, the mounting table 2, which is formed in a disc shape, has multiple heaters 21—six in this example—provided to divide the area within the mounting surface 20 on which the wafer W is placed. Hereafter, when referring to the individual heaters 21, they will be designated as the first heater 21A to the sixth heater 21F.

The first heater 21A is circular in plan view and is located in the central region (center) of the mounting surface 20. The second heater 21B is annular in plan view and is positioned on the outer periphery of the first heater 21A. Further outward from the second heater 21B are four third heaters 21C to sixth heaters 21F, which are arc-shaped in plan view. These third heaters 21C to sixth heaters 21F are arranged to form a ring surrounding the second heater 21B.

Returning to the explanation of Figure 1, the upper end of a support column 29, which extends vertically, is connected to the central part of the lower surface of the mounting table 2. A lifting mechanism 24 is provided at the lower end of the support column 29, and by moving the support column 29 up and down using the lifting mechanism 24, the mounting table 2 can be raised and lowered. In Figure 1, the mounting table 2 at the wafer transfer position is shown by a dashed line.

In Figure 1, reference numeral 25 denotes a support pin for transferring the wafer W, and it is configured to be freely movable up and down by a lifting mechanism 26. Reference numeral 22 denotes a through hole for the support pin 25, and reference numerals 27 and 28 denotes the mounting base 2 and a bellows that expands and contracts in conjunction with the lifting and lowering movement of the support pin 25, respectively.

The processing container 10 is equipped with a shower head 3 for supplying processing gas into the processing container 10, facing the mounting base 2. The shower head 3 has a gas diffusion space 31 formed inside, and its lower surface is configured as a shower plate 32 with numerous gas discharge holes 33. A gas supply system 4 is connected to the gas diffusion space 31 via a gas inlet hole 34.

The gas supply system 4 includes a film-forming gas supply unit 4A for supplying film-forming gas to the processing container 10, and a counter gas supply unit 4B for supplying a counter gas to prevent the active species formed by the thermal decomposition of the film-forming gas from flowing back into the gas diffusion space 31. In this example, we will describe the case in which monosilane ( _SiH₄ ) gas is used as the film-forming gas and argon (Ar) gas is used as the counter gas.

The film-forming gas supply unit 4A includes a _SiH4 gas supply source 41 and a gas supply passage 411, and for example, a flow rate adjustment unit 412 and a valve V1 are interposed in the gas supply passage 411 from the upstream side. The counter gas supply unit 4B includes an Ar gas supply source 42 and a gas supply passage 421, and for example, a flow rate adjustment unit 422 and a valve V2 are interposed in the gas supply passage 421 from the upstream side.

The film deposition apparatus 1 includes a control unit 100, which is, for example, a computer and has a data processing unit including a program, memory, and CPU. The program sends control signals from the control unit 100 to each part of the film deposition apparatus 1, incorporating instructions (each step) to advance the process of depositing the a-Si film, as described later. The program is stored in a computer storage medium, such as a flexible disk, compact disk, hard disk, MO (magneto-optical disk), or non-volatile memory, and installed in the control unit 100.

<Overview of the film formation process>
The following outlines the process of depositing an a-Si film using the film deposition apparatus 1 equipped with the above-described configuration.
Once the wafer W to be processed has been transported to the external vacuum transport chamber, the gate valve 12 is opened, and the transport mechanism (not shown) holding the wafer W enters the processing container 10 through the input/output port 11. Then, the wafer W is transferred to the mounting table 2 waiting at the transfer position using the support pins 25.

Subsequently, the transport mechanism is withdrawn from the processing container 10, the gate valve 12 is closed, and the pressure inside the input/output port 11 and the temperature of the wafer W are adjusted using the heater 21. Next, _SiH4 gas and Ar gas at preset flow rates are continuously supplied from the film deposition gas supply unit 4A and the counter gas supply unit 4B to the wafer W on the mounting table 2 via the shower head 3. As a result, _SiH4 is thermally decomposed on the surface of the wafer W heated by the heater 21, and an a-Si film is formed. Prior to the formation of the a-Si film, for example, an aminosilane seed layer may be formed using diisopropylaminosilane (DIPAS), and then the a-Si film may be formed by the above-described process.

Then, after the a-Si film has been deposited for a predetermined period, the supply of the deposition gas and the heating of the wafer W are stopped. At this time, the supply of the counter gas may be continued and used as a purge gas to promote the discharge of _SiH4 gas from the processing container 10. After that, the wafer W on which the film has been deposited is removed from the processing container 10 in the reverse order of its loading.

<Power supply control mechanism for heater 21>
In the film deposition apparatus 1 that performs the above-described film deposition process, as previously stated, the mounting table 2 is provided with a plurality of heaters 21, for example, six heaters 21 (first heater 21A to sixth heater 21F). In this case, if it is possible to provide temperature detection units such as thermocouples in all areas where each heater 21 is provided, control can be performed to bring the temperature of each area closer to a preset target temperature based on the temperature detection results of each area.

However, due to wiring constraints within the heater 21 body and support column 29, it may be difficult to provide a temperature detection unit for all heaters 21. Therefore, the film deposition apparatus 1 in this example is configured to provide a temperature detection unit 23 in a region corresponding to one heater 21 (for example, the first heater 21A), and to adjust the power supply to multiple heaters 21 (the first heater 21A, and the second to sixth heaters 21B to 21F) based on the temperature detection result from this temperature detection unit 23.

Figure 3 is a block diagram showing the power supply mechanism for multiple heaters 21. As shown in the figure, power supply units 5A to 5F are connected to each of the multiple heaters 21 (first heaters 21A to 21F) provided on the mounting base 2. Note that the mounting base 2 shown in Figure 3 is a longitudinal cross-sectional side view at the position A-A' indicated by the dashed line in Figure 2; therefore, the fourth heater 21D and the sixth heater 21F are not shown in the figure. The fourth heater 21D, which is not shown, is connected to power supply unit 5D, and the sixth heater 21F is connected to power supply unit 5F. These power supply units 5A to 5F may each be configured as a power source, or they may be configured as a distributor that distributes power supplied from a common power source (not shown).

In this example, the mounting base 2 is equipped with a temperature detection unit 23 corresponding to the first heater 21A located in the central region of the mounting surface 20 (Figures 2 and 3). The temperature detection unit 23 is composed of, for example, a thermocouple. The main unit 231 converts the potential difference generated by the temperature detection unit 23 into a detected temperature and outputs information indicating the detected temperature to the power supply control unit 101.

The power supply control unit 101 performs power supply control by increasing or decreasing the power supplied from the power supply units 5A to 5F to the first heaters 21A to the sixth heaters 21F based on the temperature detection values obtained from the main unit 231. Here, the power supply control unit 101 performs different power supply controls for the first heater 21A, which is located in the area where the temperature detection unit 23 is provided, and for the other second heaters 21B to the sixth heaters 21F.

Specifically, with respect to the first heater 21A, which is equipped with a temperature detection unit 23, the power supply control unit 101 reduces the power supplied from the power supply unit 5A to the first heater 21A if the temperature detected by the temperature detection unit 23 is higher than a preset target temperature. Conversely, if the temperature detected by the temperature detection unit 23 is lower than the target temperature, the power supply control unit 101 increases the power supplied from the power supply unit 5A to the first heater 21A. In this way, the power supply control unit 101 performs normal feedback control to bring the temperature detected by the temperature detection unit 23 closer to the target temperature by increasing or decreasing the power supplied to the first heater 21A. From this perspective, the first heater 21A corresponds to the "first heating unit" in this embodiment.

On the other hand, the region where the remaining second heaters 21B to the sixth heaters 21F are located does not have a temperature detection unit 23 for implementing the above-mentioned feedback control. Therefore, the power supply control unit 101 controls the power supplied to these second heaters 21B to the sixth heaters 21F by supplying power that is equal to the power supplied to the first heater 21A multiplied by a preset power supply ratio. From this perspective, the second heaters 21B to the sixth heaters 21F correspond to the "other heating units" in this embodiment.

The target temperature, which is compared to the temperature detected by the temperature detection unit 23, and the power supply ratio for controlling the power supplied from the power supply units 5B to 5F, are input from the control unit 100 to the power supply control unit 101. Note that Figure 3 shows an example where the control unit 100, which controls the entire film deposition apparatus 1, and the power supply control unit 101, which controls power supply, are configured separately. However, the control unit 100 may also have the functions of the power supply control unit 101.

<Comparison Forms>
Regarding the film deposition apparatus 1 configured to perform the power supply control described above, the inventors initially set the power supply ratio shown in Figures 4(a) and 4(b) with the aim of obtaining a uniform film thickness distribution within the plane of the wafer W for the a-Si film formed on the wafer W. This power supply ratio is set so that the amount of film deposited within the plane of the wafer W becomes more uniform. As an example, it is set based on the area ratio of the first heater 21A to the sixth heater 21F so that the amount of heat generated per unit area becomes more uniform. As will be described later using Figures 5 and 6, in the actual film deposition results there was room for improvement in the in-plane distribution of the film thickness of the a-Si film, so this example will be referred to as the "comparative form" below.

Figures 4(a) (1) to (6) show the power supply ratios to the first heater 21A to the sixth heater 21F, relative to the second heater 21B. Figure 4(b) shows the displacement of the power supply ratios compared along the dashed line shown in Figure 4(a). To avoid clutter, the reference numerals are omitted in Figure 4(a), but the arrangement of each heater 21A to 21F is the same as in the example shown in Figure 2. Furthermore, Figures 7A, 7B, and 12A to 12C, described later, also show the power supply ratios for each heater 21A to 21F in the same manner as in Figures 4(a) and (b).

According to Figures 4(a) and 4(b), the mounting surface of the wafer W is divided into a central region where the first heater 21A is provided, a peripheral region where the third heaters 21C to the sixth heaters 21F are provided, and an intermediate region located between the central and peripheral regions where the second heater 21B is provided. The first heater 21A constitutes the "central region heating section" of this embodiment, and the second heater 21B constitutes the "intermediate region heating section." Furthermore, the third heaters 21C to the sixth heaters 21F constitute the "peripheral region heating section."

According to the power supply ratio settings shown in Figures 4(a) and 4(b), the power supplied to the second heater 21B, located in the intermediate region, is the maximum. On the other hand, the power supplied to the first heater 21A, located in the central region, is approximately 0.6 times that of the second heater 21B. In other words, when feedback control is performed to increase or decrease the power supplied to the first heater 21A based on the temperature detection value of the temperature detection unit 23, so that the detected temperature approaches a preset target temperature, approximately 1.6 times the power is supplied to the second heater 21B.

Furthermore, the power supplied to the third heater 21C to the sixth heater 21F, located in the peripheral region, is approximately 0.5 times the power supplied to the second heater 21B. In other words, when the feedback control described above is performed in the first heater 21A, approximately 0.84 times the power is supplied to each of the third heater 21C to the sixth heater 21F.

Figure 5 shows the time-dependent change in the temperature detected by the temperature detection unit 23 when a wafer W is subjected to film deposition processing with the target temperature of the first heater 21A set to 560°C, under the power supply ratio explained using Figures 4(a) and (b). Figure 5 also shows the time-dependent change in the power supplied to the first heater 21A (supplied power). The horizontal axis of Figure 5 represents the elapsed time since the wafer W was placed on the mounting table 2. The left vertical axis of Figure 5 represents the temperature detected by the temperature detection unit 23, and the right vertical axis represents the power supplied to the first heater 21A (percentage value when the maximum supplied power is set to 100%; the same applies to Figures 8, 9, 13, and 14 described later).

As shown in Figure 5, after the wafer W is placed on the mounting table 2, the temperature detected by the temperature detection unit 23 decreases, and the power supplied to the first heater 21A increases to compensate for this. This is thought to be due to the temperature change resulting from placing the wafer W at room temperature. The power supplied to the first heater 21A gradually decreases while repeatedly fluctuating by small amounts (hunting), and then converges to a state where it fluctuates around a constant value. In conjunction with this change in power supply, the temperature detected by the temperature detection unit 23 fluctuates slightly around 560°C from approximately 60 seconds after the wafer W is placed. Then, from approximately 170 seconds onward, it converges to a nearly constant value (560°C).

Figure 6 shows the film thickness distribution of the a-Si film that was deposited under the above conditions, by starting the supply of the deposition gas 38.5 seconds after the wafer W was placed on the mounting stage 2.
In Figure 6, the horizontal axis represents the radial position with the center point of the wafer W as zero, and the vertical axis represents the normalized thickness with the average film thickness as the reference value. The film thickness distribution of the a-Si film deposited during the period from 0 to 120 seconds, with the start of deposition gas supply being zero seconds, is shown as a circular plot (○). Similarly, the film thickness distribution during the period from 120 to 180 seconds is shown as a triangular plot (△), the film thickness distribution during the period from 180 to 240 seconds is shown as an X plot (×), and the film thickness distribution during the period from 240 to 300 seconds is shown as a square plot (□).

As shown in Figure 6, particularly during the initial film deposition stage (0–120 seconds), the a-Si film exhibits a concave film thickness distribution, being thinner in the central region of wafer W and thicker in the peripheral region. Subsequently, as time progresses, the film thickness in the central region of wafer W increases, while the film thickness in the peripheral region decreases, approaching a more uniform film thickness distribution overall.

According to the above film deposition results, when viewed over the total deposition period from 0 to 300 seconds, the a-Si film deposited on wafer W is affected by the film thickness distribution formed in the initial stage (0-120 seconds), resulting in a concave film thickness distribution. Thus, the power supply ratio in the comparative configuration shown in Figures 4(a) and 4(b) still has room for further improvement in terms of the in-plane uniformity of the deposited a-Si film.

The following mechanism is assumed to be the reason why a concave film thickness distribution is formed in the initial stages of film deposition. As explained in Figure 5, when the wafer W is placed on the mounting stage 2, a decrease in the temperature detection value of the temperature detection unit 23 is detected, and the power supplied to the first heater 21A is increased to compensate for this. As a result, the temperature detection value of the temperature detection unit 23 gradually increases, and the amount of film deposited per unit time increases.

On the other hand, looking at the third heater 21C to the sixth heater 21F located in the peripheral region, the power supplied to these heaters 21C to 21F also increases with the power supply control described above. As previously stated, the power supply ratio for the third heater 21C to the sixth heater 21F is set to 0.51, but even at this power supply ratio, the power supply is excessive, and it is thought that the temperature in the peripheral region is higher than that in the central region. Therefore, during the period of 0-120 seconds, the amount of film deposited per unit time in the peripheral region is larger than in the central region, and it is thought that a concave film thickness distribution is formed.

<First Embodiment>
Based on the formation of the film thickness distribution in the comparative configuration described above, in the film deposition apparatus 1 of this embodiment, the period for heating the wafer W is divided into an initial heating period and a main heating period, and the power supply ratio to the second heater 21B to the sixth heater 21F is changed during these periods. The initial heating period is the period after the wafer W is placed on the mounting table 2 to stabilize the temperature of the wafer W. The main heating period is the period after the initial heating period has elapsed and includes the period during which the wafer W is processed.

Figures 7A(a) and 7A(b) show examples of power supply ratio settings during the initial heating period. Compared to the power supply ratio settings in the comparative configuration shown in Figures 4(a) and 4(b), the power supplied to the first heater 21A, located in the central region where the film thickness was relatively thin in the initial stage, is increased. In this example, the initial heating period is set to, for example, 60 seconds, corresponding to the period until the large fluctuation in the temperature detection value of the temperature detection unit 23 in the comparative configuration shown in Figure 5 recovers.

To eliminate the concave film thickness distribution in the initial stage (0-120 seconds) shown in Figure 6, a method of further reducing the power supply ratio to the third heater 21C to the sixth heater 21F in the peripheral region could be considered. However, in this case, the average in-plane film deposition rate of the wafer W would decrease, so a setting that increases the power supplied to the first heater 21A is adopted.

According to the power supply ratio setting described above, the power supply ratio to the first heater 21A in the central region and the second heater 21B in the intermediate region become equal. As a result, a central region is formed in which power supply control is performed as if the first heater 21A and the second heater 21B in these regions (central region and intermediate region) were integrated. From this perspective, the first heater 21A and the second heater 21B during the initial heating period constitute the "central heating section" of this embodiment. In contrast to the "central heating section," the third heater 21C to the sixth heater 21F, located in the outer peripheral region of the mounting surface 20, constitute the "outer peripheral heating section" of this embodiment.

According to the power supply ratio settings shown in Figures 7A(a) and 7A(b), the power supplied to the first heater 21A and the second heater 21B, which are located in the central region as described above, becomes equal. That is, when feedback control is performed to increase or decrease the power supplied to the first heater 21A based on the temperature detection value of the temperature detection unit 23, so that the detected temperature approaches a preset target temperature, the second heater 21B is supplied with the same power as the first heater 21A.

Furthermore, the power supplied to the third heater 21C to the sixth heater 21F, located in the outer periphery region, is approximately 0.5 times the power supplied to the second heater 21B. In other words, when the feedback control described above is performed by the first heater 21A, approximately 0.5 times the power is supplied to each of the third heater 21C to the sixth heater 21F.

Thus, during the initial heating period, the heaters 21 (first heater 21A to sixth heater 21F) are divided into two sections: the first heater 21A and second heater 21B, which heat the central area of the mounting surface 20, and the third heater 21C to sixth heater 21F, which heat the outer periphery. Power supply control is then performed so that the power supplied to the central heating section (first heater 21A and second heater 21B) is greater than the power supplied to the outer periphery heating section (third heater 21C to sixth heater 21F).

The ratio of power supplied to the outer peripheral heating elements (third heater 21C to sixth heater 21F) to the power supplied to the central heating elements (first heater 21A, second heater 21B) can be adjusted to a range of 0.4 to 0.8. Therefore, as long as the ratio of power supplied to the outer peripheral heating elements to the power supplied to the central heating elements satisfies the above range, it is not a mandatory requirement that the power supply ratio between the first heater 21A and the second heater 21B, which constitute the central heating elements, be equal. For example, the power supply ratio of the first heater 21A to the power supplied to the second heater 21B may be set to a value of 1.0 or less.

Next, Figures 7B(a) and 7B(b) show examples of power supply ratio settings during the main heating period. The power supply ratio during this period is set in approximately the same way as the power supply ratio settings for the comparative configuration explained using Figures 4(a) and 4(b). Specifically, the power supplied to the second heater 21B located in the intermediate region is set to the maximum, and the power supply ratio is set so that the first heater 21A located in the central region receives approximately 0.6 times the power supplied to the second heater 21B. Furthermore, the power supply ratio is set so that the third heaters 21C to the sixth heaters 21F located in the peripheral regions receive approximately 0.5 times the power supplied to the second heater 21B.

In Figure 7B(a), compared to Figure 4(a), the power supply ratios are different for the third heater 21C (0.50) and the fourth heaters 21D to 6th heaters 21F (0.52), which are located in the peripheral region. For example, the film thickness distribution in the peripheral region of the a-Si film may change along the circumferential direction of the mounting surface 20 due to the influence of the flow of the film-forming gas within the processing container 10. In this case, by differentiating the power supply ratios set for the third heaters 21C to 6th heaters 21F, which are divided along the circumferential direction of the peripheral region, the change in film thickness distribution along the circumferential direction can be offset, resulting in the formation of a more uniform film. From this perspective, the third heaters 21C to 6th heaters 21F constitute the "divided heating section" of this embodiment.

Furthermore, the setting of different power supply ratios for the divided heating sections, namely the third heater 21C to the sixth heater 21F, is not limited to the main heating period. Even during the initial heating period explained using Figures 7A(a) and 7A(b), the power supply ratios for the third heater 21C to the sixth heater 21F, which constitute the outer peripheral heating section, may be differentiated as needed.

Figure 8 shows the change over time of the power supplied to the first heater 21A (supplied power) when the wafer W is subjected to film deposition processing with the target temperature of the first heater 21A set to 560°C, under the power supply ratio explained using Figures 7A(a), (b) and 7B(a), (b). Furthermore, Figure 8 also shows the change over time of the power supply ratio of the second heater 21B/first heater 21A and the third heater 21C/first heater 21A. The horizontal axis of Figure 8 shows the elapsed time since the wafer W was placed on the mounting table 2. The vertical axis on the left of Figure 8 shows the supplied power of the first heater 21A, and the vertical axis on the right shows the power supply ratio.
As shown in Figure 8, during the initial heating period from 0 to 60 seconds, the power supplied to the first heater 21A repeatedly increased and decreased within a range of approximately 10 to 30%.

Figure 9 is a graph comparing the time-dependent change in the power supplied to the second heater 21B in the previously described comparative configuration and in this example (first embodiment). As explained using Figure 7A(b), the power supply ratio between the first heater 21A and the second heater 21B in the intermediate region is almost equal, which suppresses the supply of excessive power to the second heater 21B, and thus the increase in power supplied is reduced compared to the comparative configuration.

Figure 10 is a graph comparing the time-dependent change in the temperature detection value of the temperature detection unit 23 in the previously described comparative configuration and in this example (first embodiment). Compared to the comparative configuration shown by the thin line, the temperature drop after the wafer W is placed on the mounting stage 2 is suppressed by 0.5°C in this example. Furthermore, the period until the temperature detection value of the temperature detection unit 23 converges to a nearly constant value (560°C) is approximately 20 seconds shorter in this example than in the comparative configuration.

Figure 11 shows the film thickness distribution of the a-Si film that was deposited under the above conditions, by starting the supply of the deposition gas 70 seconds after the wafer W was placed on the mounting stage 2.
The horizontal and vertical axes in Figure 11 are the same as in Figure 6. The film thickness distribution of the a-Si film deposited during the period from 0 to 180 seconds, with the start of film deposition gas supply being zero seconds, is shown as a circular plot (○). Similarly, the film thickness distribution during the period from 180 to 300 seconds is shown as a triangular plot (△), and the film thickness distribution during the period from 300 to 600 seconds is shown as an X plot (×).

According to Figure 11, the concave film thickness distribution formed in the comparative configuration was not observed during the 0-180 second period. Furthermore, during the 0-180 second period, a region of thinner film thickness was observed at a position of -100 mm from the center. Aside from this point, compared to the comparative configuration shown in Figure 6, no extreme differences in film thickness distribution were observed between the initial stage (0-180 seconds) and subsequent stages (180-300 seconds, 300-600 seconds). Therefore, when considering the total film deposition period from 0 to 600 seconds, the a-Si film deposited using the method according to the first embodiment can be said to have higher in-plane uniformity than the a-Si film related to the comparative configuration.

The film deposition apparatus 1 according to this embodiment has the following advantages. After the wafer W is placed on the mounting table 2, the power supply ratio to the multiple heaters 21 is changed during the initial heating period to stabilize the temperature of the wafer W, and during the main heating period which includes the period for processing the wafer W after the initial heating period has elapsed. Therefore, compared to the case where film deposition is performed after waiting for the temperature of the entire mounting surface 20 to stabilize without changing the power supply ratio, the influence of temperature changes associated with placing an unheated wafer W can be reduced. As a result, the processing of the wafer W can be started in a shorter time.

<Second Embodiment>
In the second embodiment shown in Figures 12A to 12C, the initial heating period for stabilizing the temperature of the wafer W is further divided into multiple periods.
In the first period to be implemented, the multiple heaters 21A to 21F are divided into a central region heating section (first heater 21A), an intermediate region heating section (third heater 21C), and a peripheral region heating section (third heater 21C to sixth heater 21F), similar to the example described using Figures 7B(a) and (b) of the first embodiment. Power supply control is then performed so that the power supplied to the intermediate region heating section (third heater 21C) is greater than the power supplied to the central region heating section (first heater 21A) and the peripheral region heating sections (third heater 21C to sixth heater 21F) (Figures 12A and 12B). The first period corresponds to the "other period" in this embodiment.

On the other hand, in the second period that follows, the first heater 21A and the second heater 21B constitute the central heating section, and the third heater 21C to the sixth heater 21F constitute the outer peripheral heating section, similar to the example described using Figures 7A(a) and 7A(b) of the first embodiment. Power supply control is then performed so that the power supplied to the central heating section (first heater 21A, second heater 21B) is greater than the power supplied to the outer peripheral heating section (third heater 21C to sixth heater 21F) (Figure 12C). The second period corresponds to "Period 1" in this embodiment.

Figure 13 shows the change over time of the power supplied to the first heater 21A (supplied power) when the wafer W is subjected to film deposition with the target temperature of the first heater 21A set to 560°C. Furthermore, Figure 13 also shows the change over time of the power supply ratio between the second heater 21B/first heater 21A and the third heater 21C/first heater 21A. The horizontal and vertical axes in Figure 13 are the same as in Figure 8.

As can be seen from the power supply ratio shown by the thin solid line and dashed line in Figure 13, in the second embodiment, power supply control for the first period is performed first. That is, after placing the wafer W on the mounting stage 2 with the power supply ratio settings shown in Figures 12A(a) and (b), the power supply ratio is changed to the settings shown in Figures 12B(a) and (b) after, for example, 10 seconds. Both of these periods correspond to the first period. During this first period, the ratio of the power supplied to the central region heating section (first heater 21A) to the power supplied to the intermediate region heating section (second heater 21B) is gradually increased (Figure 12A(b) → Figure 12B(b)).

Then, after supplying power for, for example, 20 seconds at the power supply ratio shown in Figures 12B(a) and (b), the power supply ratio is changed to the settings shown in Figures 12C(a) and (b). This setting change enables power supply control for the second period. In this example (second embodiment), after supplying power for, for example, 30 seconds at the power supply ratio shown in Figures 12C(a) and (b), power is again supplied for, for example, 10 seconds at the power supply ratio shown in Figures 12B(a) and (b). After that, the power supply ratio is changed to the settings shown in Figures 12A(a) and (b), and the supply of the film-forming gas is started in this state (main heating period).

Figure 14 is a graph comparing the time-dependent change in power supplied to the second heater 21B in the previously described comparative configuration (dashed line) and the first embodiment (thin line), and in the second embodiment of this example (thick line). Similar to the first embodiment, in the first period, the increase in power supplied is suppressed compared to the comparative configuration because excessive power supply to the second heater 21B is inhibited.

Furthermore, as previously described, in this example (the second embodiment), during the first period, the ratio of the power supplied to the central region heating section (first heater 21A) to the power supplied to the intermediate region heating section (second heater 21B) is gradually increased. This adjustment reduces the fluctuation range of the supplied power compared to the first embodiment (Figure 14).

Figure 15 is a graph comparing the time-dependent change in the temperature detection value of the temperature detection unit 23 in the previously described comparative configuration (dashed line) and the first embodiment (thin line), and in the second embodiment of this example (thick line). Compared to the first embodiment shown by the thin line, in this example, the temperature drop after the wafer W is placed on the mounting stage 2 is further suppressed by 0.25°C. Furthermore, the time it takes for the temperature detection value of the temperature detection unit 23 to converge to a nearly constant value (560°C) is approximately 45 seconds shorter in this example than in the comparative configuration.

Figure 16 shows the film thickness distribution of the a-Si film that was deposited under the above conditions, by starting the supply of the deposition gas 70 seconds after the wafer W was placed on the mounting stage 2.
The horizontal and vertical axes in Figure 16 are the same as in Figure 6 described above. The film thickness distribution of the a-Si film deposited during the period from 0 to 180 seconds, with the start of film deposition gas supply being zero seconds, is shown as circular plots (○). Similarly, the film thickness distribution during the period from 180 to 300 seconds is shown as triangular plots (△).

According to Figure 16, compared to the comparative configuration shown in Figure 6, no extreme differences in film thickness distribution were observed between the initial stage (0-180 seconds) and the subsequent stage (180-300 seconds). Therefore, based on the above deposition results, it can be said that the a-Si film deposited using the method of the second embodiment has higher in-plane uniformity than the a-Si film related to the comparative configuration, when viewed over the total deposition period from 0 to 300 seconds.

<Variations>
The configuration of the multiple heaters 21 formed inside the mounting base 2 is not limited to the example shown in Figure 2. For example, instead of the multiple divided third heaters 21C to sixth heaters 21F arranged in the peripheral region, an annular heater 21 formed by connecting them may be provided. Alternatively, the annular second heater 21B may be divided in the circumferential direction. Furthermore, the example is not limited to providing two annular heaters 21 (second heater 21B and third heaters 21C to sixth heaters 21F) concentrically around the circular first heater 21A, but may also provide three or more annular heaters 21.

In the examples shown in Figures 7A and 12C, the central heating section is configured using the first heater 21A and the second heater 21B, while the outer peripheral heating section is configured using the third heater 21C to the sixth heater. Alternatively, for example, the central heating section can be configured using only the first heater 21A, and the outer peripheral heating section can be configured using the second heater 21B and the third heater 21C to the sixth heater.

During the initial heating period, it is not essential to control the power supply so that the power supplied to the central heating section (e.g., the first heater 21A and the second heater 21B) is greater than the power supplied to the outer heating section (e.g., the third heater 21C to the sixth heater). Depending on the film thickness distribution formed when the processing corresponding to the comparative configuration is performed, it is also possible to control the power supply during the initial heating period so that, for example, the power supplied to the central heating section is less than the power supplied to the outer heating section.

Furthermore, it is not essential to control the power supply so that the power supplied to the intermediate heating section (e.g., the second heater 21B) is greater than the power supplied to the central heating section (e.g., the second heater 21A) and the peripheral heating sections (e.g., the third heater 21C to the sixth heater) during the main heating period. Based on preliminary experiments, power supply control with other power supply ratios may be implemented.

Furthermore, the region in which the temperature detection unit 23 performs temperature detection is not limited to the region where the first heater 21A is provided. Other heaters 21B to 21F may be selected as a single heating unit, and the temperature of the region in which they are located may be detected by the temperature detection unit 23.

The switching between the initial heating period and the main heating period, and the switching between the first and second periods within the initial heating period, are not limited to being performed after a predetermined period has elapsed. For example, these switching may be performed when the temperature detected by the temperature detection unit 23 reaches a predetermined target temperature, or when the power supplied from the power supply units 5A to 5F reaches a predetermined power level.

In the above example, the case of forming an a-Si film on a wafer W was used as an example. However, the film formed by applying the technology of this disclosure may be a metal oxide film or a metal nitride film for forming an insulating film, or it may be a metal film.

Furthermore, the processing performed on the wafer W is not limited to film deposition. It may also include etching, where an etching gas is supplied to the film formed on the wafer W to perform etching, or modification, where a modification gas is used to modify the material on the wafer W. When performing various processing, including film deposition, a plasma mechanism may be used to plasmaize the processing gases such as the film deposition gas, etching gas, and modification gas.

The embodiments disclosed herein should be considered in all respects as illustrative and not restrictive. The above embodiments may be omitted, replaced, or modified in various ways without departing from the scope and spirit of the appended claims.

1. Film deposition apparatus 2. Mounting table 21. Heater 23. Temperature detection unit 101. Power supply control units 5A to 5F
Power supply unit

Claims (18)

A device for processing substrates,
A mounting platform provided inside the processing container and having a mounting surface on which the substrate is placed,
To heat different areas of the mounting surface, a plurality of heating units are provided on the mounting base described above,
Each of the aforementioned heating units is provided with a plurality of power supply units that supply power to it,
A temperature detection unit for detecting the temperature of a region where one of the plurality of heating units is provided,
The system includes a power supply control unit that controls the power supply of a plurality of power supply units, such that, based on the temperature detected by the temperature detection unit, it supplies power to one heating unit so that the detected temperature approaches a preset target temperature, and supplies power to the other heating units equal to the power supplied to the first heating unit multiplied by a preset power supply ratio.
The power supply control unit is a device that changes the power supply ratio during an initial heating period to stabilize the temperature of the substrate after the substrate is placed on the stand described above, and a main heating period which includes a period during which processing of the substrate is carried out after the initial heating period has elapsed. The apparatus according to claim 1, wherein the aforementioned heating element is a heating element provided in the center of the aforementioned mounting surface. The apparatus according to claim 1, wherein the initial heating period includes a period during which the plurality of heating units are divided into a central heating unit that heats the central region of the mounting surface and an outer peripheral heating unit that heats the outer peripheral region of the mounting surface, and the power supply control is performed so that the power supplied to the central heating unit is greater than the power supplied to the outer peripheral heating unit. The apparatus according to claim 3, wherein the ratio of the power supplied to the outer peripheral heating section to the power supplied to the central heating section is within the range of 0.4 to 0.8. The apparatus according to claim 3, wherein, when the period during which power supply control is performed so that the power supplied to the central heating section is greater than the power supplied to the outer peripheral heating section is defined as one period, the initial heating period further includes another period during which the plurality of heating sections are divided into a central region heating section that heats the central region of the surface described above, a peripheral region heating section that heats the peripheral region of the surface described above, and an intermediate region heating section that heats the intermediate region between the central region and the peripheral region, and the power supply control is performed so that the power supplied to the intermediate region heating section is greater than the power supplied to the central region heating section and the peripheral region heating section. The apparatus according to claim 5, wherein the power supply control unit first performs power supply control for the other period, and during the other period, gradually increases the ratio of power supplied to the central region heating unit to the power supplied to the intermediate region heating unit, and then performs power supply control for the first period. The apparatus according to claim 1, wherein the plurality of heating units include a plurality of divided heating units arranged along the circumferential direction of the mounting surface described above, and the power supply control unit controls the power supply to the plurality of power supply units so as to differentiate the power supply ratios set for these divided heating units. During the main heating period, the power supply control unit divides the plurality of heating units into a central region heating unit that heats the central region of the mounting surface, a peripheral region heating unit that heats the peripheral region of the mounting surface, and an intermediate region heating unit that heats the intermediate region between the central region and the peripheral region, and controls the power supply of the plurality of power supply units so that the power supplied to the intermediate region heating unit is greater than the power supplied to the central region heating unit and the peripheral region heating unit, as described in claim 1. The apparatus according to claim 1, further comprising a film-forming gas supply unit that supplies a film-forming gas to the processing container for performing the film-forming process on the substrate. A method for processing a substrate,
A substrate processing apparatus is used, comprising: a mounting stand provided in a processing container and having a mounting surface on which the substrate is placed; a plurality of heating units provided on the mounting stand for heating different areas of the mounting surface; a plurality of power supply units for supplying power to each of the plurality of heating units; and a temperature detection unit for detecting the temperature of the area on which one of the plurality of heating units is provided.
The process involves controlling the power supply of the multiple power supply units, such that, based on the temperature detected by the temperature detection unit, power is supplied to the first heating unit so that the detected temperature approaches a preset target temperature, and power is supplied to the other heating units equal to the power supplied to the first heating unit multiplied by a preset power supply ratio.
A method comprising the step of changing the power supply ratio during an initial heating period to stabilize the temperature of the substrate after the substrate has been placed on the mounting table, and a main heating period which includes a period during which processing of the substrate is carried out after the initial heating period has elapsed. The method according to claim 10, wherein the heating element provided in the center of the aforementioned mounting surface is used as the first heating element. The method according to claim 10, wherein, in the step of performing the power supply control, the initial heating period includes a period during which the plurality of heating units are divided into a central heating unit that heats the central region of the mounting surface and an outer peripheral heating unit that heats the outer peripheral region of the mounting surface, and the power supply control is performed such that the power supplied to the central heating unit is greater than the power supplied to the outer peripheral heating unit. The method according to claim 12, wherein the ratio of the power supplied to the outer peripheral heating section to the power supplied to the central heating section is within the range of 0.4 to 0.8. The method according to claim 12, wherein, in the process of performing the power supply control, when the period during which power supply control is performed so that the power supplied to the central heating section is greater than the power supplied to the outer peripheral heating section is defined as one period, the initial heating period further includes another period during which the plurality of heating sections are divided into a central region heating section that heats the central region of the surface described above, a peripheral region heating section that heats the peripheral region of the surface described above, and an intermediate region heating section that heats the intermediate region between the central region and the peripheral region, and the power supply control is performed so that the power supplied to the intermediate region heating section is greater than the power supplied to the central region heating section and the peripheral region heating section. The method according to claim 14, wherein, in the step of performing the power supply control, the power supply control for the other period is performed first, and during the other period, the ratio of the power supplied to the central region heating section to the power supplied to the intermediate region heating section is gradually increased, and then the power supply control for the first period is performed. The method according to claim 10, wherein the plurality of heating units include a plurality of divided heating units arranged along the circumferential direction of the mounting surface described above, and in the step of performing the power supply control, the power supply control of the plurality of power supply units is performed so as to make the power supply ratios set for these divided heating units different. The method according to claim 10, wherein, in the step of performing the power supply control, during the main heating period, the plurality of heating units are divided into a central region heating unit that heats the central region of the mounting surface, a peripheral region heating unit that heats the peripheral region of the mounting surface, and an intermediate region heating unit that heats the intermediate region between the central region and the peripheral region, and the power supply control is performed so that the power supplied to the intermediate region heating unit is greater than the power supplied to the central region heating unit and the peripheral region heating unit. The method according to claim 10, further comprising the step of supplying a film-forming gas to the processing container during the main heating period for performing a film-forming process on the substrate.