Substrate processing method and substrate processing apparatus

Abstract

To provide technique enabling control of an introduction amount of heavy hydrogen into an insulating film.SOLUTION: A substrate processing method according to an embodiment of a present disclosure, includes: a step of housing a substrate having an insulating film on a front surface in a processing container; a step of exposing the insulating film to plasma generated from gas including deuterium gas in a state where the substrate housed in the processing container is maintained at a first temperature and introducing the deuterium gas into the insulating film; and a step of performing heat treatment on the insulating film without exposing the insulating film to the plasma, in a state where the substrate housed in the processing container is controlled to a second temperature different from the first temperature, thereby adjusting concentration of the deuterium gas introduced into the insulating film.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a substrate processing method and a substrate processing apparatus.

Background Art

[0002] A technique is known in which a ratio of deuterium to hydrogen in a semiconductor substrate is larger than a ratio of deuterium to hydrogen existing in nature at an interface between the semiconductor substrate and a gate insulating film formed on the semiconductor substrate (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present disclosure provides a technique capable of controlling an amount of deuterium introduced into an insulating film.

Means for Solving the Problems

[0005] A substrate processing method according to an aspect of the present disclosure includes: a step of accommodating a substrate having an insulating film on a surface thereof in a processing container; a step of exposing the insulating film to plasma generated from a gas containing deuterium gas while maintaining the substrate accommodated in the processing container at a first temperature, and introducing deuterium into the insulating film; and a step of heat-treating the insulating film without exposing it to the plasma while controlling the substrate accommodated in the processing container to a second temperature different from the first temperature, and adjusting a concentration of the deuterium introduced into the insulating film.

Effects of the Invention

[0006] According to the present disclosure, an amount of deuterium introduced into an insulating film can be controlled.

Brief Description of the Drawings

[0007] [Figure 1] Figure 1 is a flowchart showing the substrate processing method according to the embodiment. [Figure 2] Figure 2 is a timing chart showing the substrate processing method according to the embodiment. [Figure 3] Figure 3 is a longitudinal cross-sectional view showing a substrate processing apparatus according to an embodiment. [Figure 4] Figure 4 is a cross-sectional view showing a substrate processing apparatus according to an embodiment of the present invention. [Figure 5] Figure 5 shows the measurement results of the deuterium concentration in the silicon nitride film. [Modes for carrying out the invention]

[0008] Hereinafter, exemplary embodiments of the present disclosure, not limited to those described herein, will be described with reference to the attached drawings. In all attached drawings, identical or corresponding members or components are denoted by the same or corresponding reference numerals, and redundant descriptions are omitted.

[0009] [Substrate processing method] The substrate processing method according to the embodiment will be described with reference to Figures 1 and 2. Figure 1 is a flowchart of the substrate processing method according to the embodiment. Figure 2 is a timing chart showing the substrate processing method according to the embodiment. Figure 2 shows the temperature of the substrate at each step of the substrate processing method according to the embodiment.

[0010] As shown in Figure 1, the substrate processing method according to this embodiment includes a preparation step S10, a temperature stabilization step S20, a deuterium plasma step S30, and a concentration adjustment step S40.

[0011] Preparation step S10 includes preparing a substrate having an insulating film on its surface. The substrate may be, for example, a semiconductor wafer. The insulating film may be, for example, a silicon nitride film or a silicon oxynitride film.

[0012] The temperature stabilization step S20 is performed after the preparation step S10. The temperature stabilization step S20 includes adjusting and stabilizing the temperature of the substrate to a first temperature. The first temperature may be, for example, 600°C or higher and 700°C or lower. In the examples of Figures 2(a) to (c), the first temperature is 630°C.

[0013] The deuterium plasma process S30 is performed after the temperature stabilization process S20. In the deuterium plasma process S30, while the substrate temperature is maintained at a first temperature, the insulating film is exposed to plasma generated from a plasma generating gas containing deuterium gas, thereby introducing deuterium into the insulating film. The plasma generating gas may further contain an inert gas. The inert gas may be, for example, nitrogen gas or argon gas.

[0014] The concentration adjustment step S40 is performed after the deuterium plasma step S30. The concentration adjustment step S40 includes adjusting the concentration of deuterium introduced into the insulating film by heat-treating the insulating film without exposing it to plasma, while controlling the substrate temperature to a second temperature different from the first temperature. When the insulating film is heat-treated without exposure to plasma, it is thought that the higher the temperature, the easier it is for deuterium to desorb from the insulating film. Therefore, by heat-treating the insulating film without exposing it to plasma, while controlling the substrate temperature to a second temperature different from the first temperature, the deuterium concentration in the insulating film can be adjusted.

[0015] The second temperature may be, for example, higher than the first temperature. In this case, since the insulating film is heat-treated at a higher temperature than the first temperature, deuterium is more easily desorbed from the insulating film compared to when the insulating film is heat-treated at the first temperature. As a result, the deuterium concentration in the insulating film decreases. The second temperature may be, for example, lower than the first temperature. In this case, since the insulating film is heat-treated at a lower temperature than the first temperature, deuterium is less easily desorbed from the insulating film compared to when the insulating film is heat-treated at the first temperature. As a result, the deuterium concentration in the insulating film increases. The second temperature may be, for example, a constant temperature, or a temperature that changes over time. In Figure 2(a), the second temperature is 700°C. In Figure 2(c), the second temperature is a temperature that continuously changes from 630°C to 570°C over time. Figure 2(b) shows the case where the second temperature is the same as the first temperature for comparison.

[0016] The second temperature may be determined, for example, based on a desired deuterium concentration. The second temperature may be determined, for example, based on a desired deuterium concentration and relational information showing the relationship between the deuterium concentration and the second temperature. This relational information can be calculated, for example, by conducting experiments beforehand.

[0017] The concentration adjustment step S40 may include, for example, supplying deuterium gas to the substrate. The concentration adjustment step S40 may be performed without, for example, supplying deuterium gas to the substrate. The concentration adjustment step S40 may include, for example, supplying an inert gas to the substrate.

[0018] As described above, according to the substrate processing method according to the embodiment, the concentration adjustment step S40 is performed after the deuterium plasma step S30. In the deuterium plasma step S30, with the temperature of the substrate maintained at the first temperature, the insulating film is exposed to the plasma generated from the plasma generation gas containing deuterium gas, and deuterium is introduced into the insulating film. In the concentration adjustment step S40, with the temperature of the substrate controlled to a second temperature different from the first temperature, the insulating film is heat-treated without being exposed to the plasma, and the concentration of deuterium introduced into the insulating film is adjusted. Thus, according to the substrate processing method according to the embodiment, the amount of deuterium introduced into the insulating film can be controlled by changing the temperature of the substrate in the concentration adjustment step S40 without changing the conditions of the deuterium plasma step S30.

[0019] By the way, when it is desired to increase the amount of deuterium introduced into the insulating film, methods of changing the conditions of the deuterium plasma step S30 can be considered, such as increasing the temperature of the substrate, increasing the RF power, or increasing the time for exposing the insulating film to the deuterium plasma in the deuterium plasma step S30. However, from the perspective of safety, there may be cases where the conditions of the deuterium plasma step S30 cannot be changed. In contrast, in the substrate processing method according to the embodiment, since the amount of deuterium introduced into the insulating film can be controlled without changing the conditions of the deuterium plasma step S30, it is particularly effective when the conditions of the deuterium plasma step S30 cannot be changed.

[0020] 〔Substrate Processing Apparatus〕 Referring to FIGS. 3 and 4, the substrate processing apparatus 100 according to the embodiment will be described. As shown in FIGS. 3 and 4, the substrate processing apparatus 100 mainly includes a processing container 1, a gas supply unit 20, a plasma generation unit 30, an exhaust unit 40, a heating unit 50, and a control unit 60.

[0021] The processing container 1 has a vertical, cylindrical shape with a top that is open at the bottom. The entire processing container 1 is made of, for example, quartz. A top plate 2 is provided near the top of the processing container 1, and the area below the top plate 2 is sealed. The top plate 2 is made of, for example, quartz. A cylindrical metal manifold 3 is connected to the opening at the bottom of the processing container 1 via a sealing member 4. The sealing member 4 may be, for example, an O-ring.

[0022] The manifold 3 supports the lower end of the processing container 1. The boat 5 is inserted into the processing container 1 from below the manifold 3. The boat 5 holds multiple substrates W (e.g., 25 to 150) in a substantially horizontal position with spacing along the vertical direction. The substrates W may be, for example, semiconductor wafers. The boat 5 is made of, for example, quartz. The boat 5 has, for example, three support columns 6, and the multiple substrates W are supported by grooves formed in the support columns 6.

[0023] Boat 5 is placed on a turntable 8 via an insulating tube 7. The insulating tube 7 is made of, for example, quartz. The insulating tube 7 suppresses heat dissipation from the opening at the lower end of the manifold 3. The turntable 8 is supported on a rotating shaft 10. The opening at the lower end of the manifold 3 is opened and closed by a cover 9. The cover 9 is made of, for example, a metal material such as stainless steel. The rotating shaft 10 passes through the cover 9.

[0024] A magnetic fluid seal 11 is provided at the penetration portion of the rotating shaft 10. The magnetic fluid seal 11 hermetically seals the rotating shaft 10 and supports it so that it can rotate. A sealing member 12 is provided between the periphery of the lid 9 and the lower end of the manifold 3 to maintain airtightness inside the processing container 1. The sealing member 12 may be, for example, an O-ring.

[0025] The rotating shaft 10 is attached to the tip of an arm 13 supported by a lifting mechanism such as a boat elevator. As the arm 13 moves up and down, the boat 5, the insulation cylinder 7, the rotating base 8, and the lid 9 move up and down together with the rotating shaft, and are inserted into and removed from the processing container 1.

[0026] The gas supply unit 20 supplies various gases into the processing container 1. The gas supply unit 20 has, for example, four gas nozzles 21 to 24. The gas supply unit 20 may also have, for example, another gas nozzle in addition to the four gas nozzles 21 to 24.

[0027] The gas nozzle 21 is made of, for example, quartz and has an L-shape that penetrates the side wall of the manifold 3 inward, is bent upward, and extends vertically. The vertical portion of the gas nozzle 21 is located outside the plasma generation space P, for example, on the side of the plasma generation space P that is closer to the center C of the processing vessel 1 within the processing vessel 1. The vertical portion of the gas nozzle 21 may also be located on the side of the exhaust port 41 that is closer to the center C of the processing vessel 1 within the processing vessel 1. The gas nozzle 21 is connected to one or more processing gas supply sources. Multiple gas holes 21a are formed at intervals in the vertical portion of the gas nozzle 21 over a length corresponding to the substrate support range of the boat 5. The gas holes 21a are oriented, for example, toward the center C of the processing vessel 1 and discharge the processing gas horizontally toward the center C of the processing vessel 1. The gas holes 21a may be oriented, for example, toward the plasma generation space P side, or toward the inner wall side near the processing vessel 1.

[0028] The gas nozzle 22 is made of, for example, quartz and has an L-shape that penetrates the side wall of the manifold 3 inward, is bent upward, and extends vertically. The vertical portion of the gas nozzle 22 is located outside the plasma generation space P, for example, on the side of the plasma generation space P that is closer to the center C of the processing vessel 1 within the processing vessel 1. The vertical portion of the gas nozzle 22 may also be located on the side of the exhaust port 41 that is closer to the center C of the processing vessel 1 within the processing vessel 1. The gas nozzle 22 is connected to one or more processing gas supply sources. Multiple gas holes 22a are formed at intervals in the vertical portion of the gas nozzle 22 along the vertical length corresponding to the substrate support range of the boat 5. The gas holes 22a are oriented, for example, toward the center C of the processing vessel 1 and discharge the processing gas horizontally toward the center C of the processing vessel 1. The gas holes 22a may be oriented, for example, toward the plasma generation space P side, or toward the inner wall side near the processing vessel 1.

[0029] The gas nozzle 23 is made of, for example, quartz and has an L-shape that penetrates the side wall of the manifold 3 inward, is bent upward, and extends vertically. The vertical portion of the gas nozzle 23 is provided in the plasma generation space P. The gas nozzle 23 is connected to one or more processing gas supply sources. The processing gas supply sources may include, for example, a deuterium gas supply source. Multiple gas holes 23a are formed at intervals in the vertical portion of the gas nozzle 23 along the vertical length corresponding to the substrate support area of ​​the boat 5. The gas holes 23a are oriented, for example, toward the center C of the processing container 1 and discharge the processing gas horizontally toward the center C of the processing container 1.

[0030] The gas nozzle 24 is made of, for example, quartz and has a straight pipe shape that extends horizontally through the side wall of the manifold 3. The tip of the gas nozzle 24 is located outside the plasma generation space P, for example, inside the processing container 1. The gas nozzle 24 is connected to a purge gas supply source. The tip of the gas nozzle 24 is open, and purge gas is supplied into the processing container 1 from the opening. Examples of purge gases include inert gases such as argon gas and nitrogen gas.

[0031] The plasma generation unit 30 is provided in a part of the side wall of the processing vessel 1. The plasma generation unit 30 generates plasma from the processing gas supplied from the gas nozzle 23. The plasma generation unit 30 includes a plasma compartment wall 32, a pair of plasma electrodes 33, a power supply line 34, an RF power supply 35, and an insulating protective cover 36.

[0032] The plasma compartment wall 32 is airtightly welded to the outer wall of the processing vessel 1. The plasma compartment wall 32 is made of, for example, quartz. The plasma compartment wall 32 has a concave cross-section and covers the opening 31 formed in the side wall of the processing vessel 1. The opening 31 is formed to be elongated in the vertical direction so as to cover all the substrates W supported by the boat 5 in the vertical direction. Gas nozzles 23 are arranged in the plasma generation space P, which is an inner space defined by the plasma compartment wall 32 and in communication with the inside of the processing vessel 1. Gas nozzles 21 and 22 are provided at positions close to the substrates W along the inner wall of the processing vessel 1 outside the plasma generation space P.

[0033] A pair of plasma electrodes 33 each have an elongated shape and are arranged facing each other vertically on the outer surfaces of the walls on both sides of the plasma compartment wall 32. A power supply line 34 is connected to the lower end of each plasma electrode 33.

[0034] The power supply line 34 electrically connects each plasma electrode 33 to the RF power supply 35. For example, one end of the power supply line 34 is connected to the lower end, which is the side of the short edge of each plasma electrode 33, and the other end is connected to the RF power supply 35.

[0035] The RF power supply 35 is electrically connected to the lower end of each plasma electrode 33 via a power supply line 34. The RF power supply 35 supplies RF power of, for example, 13.56 MHz to a pair of plasma electrodes 33. This applies RF power to the plasma generation space P defined by the plasma partition wall 32.

[0036] The insulating protective cover 36 is attached to the outside of the plasma compartment wall 32 so as to cover the plasma compartment wall 32. A refrigerant passage (not shown) is provided in the inner portion of the insulating protective cover 36. The plasma electrode 33 is cooled by flowing a refrigerant such as cooled nitrogen gas through the refrigerant passage. A shield (not shown) may be provided between the plasma electrode 33 and the insulating protective cover 36 so as to cover the plasma electrode 33. The shield is made of a good conductor such as metal and is electrically grounded.

[0037] The exhaust unit 40 is provided in an exhaust port 41 formed in the side wall portion of the processing container 1 facing the opening 31. The exhaust port 41 is formed to be long and narrow vertically, corresponding to the boat 5. A cover member 42, formed in a U-shape in cross-section, is attached to the portion of the processing container 1 corresponding to the exhaust port 41 so as to cover the exhaust port 41. The cover member 42 extends upward along the side wall of the processing container 1. An exhaust pipe 43 is connected to the lower part of the cover member 42. A pressure regulating valve 44 and a vacuum pump 45 are provided in the exhaust pipe 43 in order from the upstream side to the downstream side in the direction of gas flow. Based on the control of the control unit 60, the exhaust unit 40 operates the pressure regulating valve 44 and the vacuum pump 45, adjusting the pressure inside the processing container 1 by the pressure regulating valve 44 while drawing gas from inside the processing container 1 into the vacuum pump 45.

[0038] The heating section 50 includes a heater 51. The heater 51 has a cylindrical shape that surrounds the processing container 1 on its radially outer side. The heater 51 heats each substrate W housed inside the processing container 1 by heating the entire side circumference of the processing container 1.

[0039] The control unit 60 controls the operation of each part of the substrate processing apparatus 100, for example. The control unit 60 may be, for example, a computer. The computer program that controls the operation of each part of the substrate processing apparatus 100 is stored in a storage medium. The storage medium may be, for example, a flexible disk, compact disk, hard disk, flash memory, DVD, etc.

[0040] [Operation of the circuit board processing unit] The operation when the substrate processing method according to the embodiment is carried out in the substrate processing apparatus 100 will be described below.

[0041] First, the control unit 60 controls the lifting mechanism to load the boat 5, which holds multiple substrates W, into the processing container 1, and then seals the opening at the lower end of the processing container 1 airtight with the lid 9. Each substrate W is a substrate having an insulating film on its surface.

[0042] Next, the control unit 60 controls the exhaust unit 40 and the heating unit 50 to execute the temperature stabilization process S20. Specifically, first, the control unit 60 controls the exhaust unit 40 to reduce the pressure inside the processing container 1 to a predetermined level, and then controls the heating unit 50 to adjust and stabilize the temperature of the substrate W to a first temperature.

[0043] Next, the control unit 60 controls the gas supply unit 20, plasma generation unit 30, exhaust unit 40, and heating unit 50 to execute the deuterium plasma process S30. Specifically, first, the control unit 60 controls the heating unit to maintain the temperature of the substrate W at a first temperature, then controls the gas supply unit 20 to supply deuterium gas into the processing container 1, and controls the plasma generation unit 30 to supply RF power from the RF power supply 35 to the pair of plasma electrodes 33. As a result, plasma is generated from the deuterium gas supplied into the processing container 1. Consequently, the insulating film is exposed to the plasma generated from the deuterium gas, and deuterium is introduced into the insulating film.

[0044] Next, the control unit 60 controls the gas supply unit 20, plasma generation unit 30, exhaust unit 40, and heating unit 50 to execute the concentration adjustment process S40. Specifically, first, the control unit 60 controls the plasma generation unit 30 to stop the supply of RF power from the RF power supply 35 to the pair of plasma electrodes 33. Next, the control unit 60 controls the gas supply unit 20 to stop the supply of deuterium gas into the processing container 1. The control unit 60 also controls the heating unit 50 to control the temperature of the substrate W to a second temperature. As a result, the insulating film is heat-treated without being exposed to plasma, and the concentration of deuterium introduced into the insulating film is adjusted.

[0045] Next, the control unit 60 increases the pressure inside the processing container 1 to atmospheric pressure, then lowers the temperature inside the processing container 1 to the discharge temperature, and finally controls the lifting mechanism to discharge the boat 5 from inside the processing container 1.

[0046] [Examples] This section describes an example in which it was confirmed that the amount of deuterium introduced into the insulating film can be controlled by the substrate processing method according to the embodiment.

[0047] In this example, a substrate having a silicon nitride film on its surface was prepared, and the prepared substrate was placed in the substrate processing apparatus 100 described above. Deuterium was then introduced into the silicon nitride film according to conditions 1 to 3 shown below. Subsequently, the deuterium concentration in the silicon nitride film was measured by secondary ion mass spectrometry (SIMS). The silicon nitride film is an example of an insulating film.

[0048] (Condition 1) Under Condition 1, the temperature stabilization process S20, the deuterium plasma process S30, and the concentration adjustment process S40 were performed on the prepared substrate in this order. In the temperature stabilization process S20 and the deuterium plasma process S30, the substrate temperature was maintained at 630°C. In the concentration adjustment process S40, with the substrate temperature controlled to 700°C, heat treatment was performed while supplying deuterium gas and nitrogen gas into the processing container 1 without exposing the silicon nitride film to plasma.

[0049] (Condition 2) In condition 2, during the concentration adjustment step S40, the substrate temperature was controlled to 630°C, and heat treatment was performed by supplying only nitrogen gas into the processing container 1 without exposing the silicon nitride film to plasma. All other conditions were the same as in condition 1.

[0050] (Condition 3) In condition 3, during the concentration adjustment step S40, the substrate temperature was continuously reduced from 630°C to 570°C while heat treatment was performed by supplying only nitrogen gas into the processing container 1 without exposing the silicon nitride film to plasma. All other conditions were the same as in condition 1.

[0051] Figure 5 shows the measurement results of the deuterium concentration in the silicon nitride film. Figure 5 shows the deuterium concentration in the silicon nitride film into which deuterium was introduced under conditions 1 to 3. In Figure 5, the horizontal axis represents the substrate temperature [°C] during the concentration adjustment process S40, and the vertical axis represents the deuterium concentration [atoms / cm³] in the silicon nitride film. 3 This indicates the deuterium concentration in the silicon nitride film, which represents the maximum value of the deuterium concentration in the silicon nitride film measured by SIMS in the film thickness direction.

[0052] As shown in Figure 5, the deuterium concentration in the silicon nitride film is lower under condition 1 compared to condition 2. This result indicates that the deuterium concentration in the silicon nitride film can be lowered by supplying deuterium gas into the processing vessel 1 after the deuterium plasma process S30 and raising the substrate temperature to a higher level than the substrate temperature during the deuterium plasma process S30.

[0053] As shown in Figure 5, the deuterium concentration in the silicon nitride film is higher under condition 3 compared to condition 2. This result indicates that the deuterium concentration in the silicon nitride film can be increased by lowering the substrate temperature to a level lower than that of the substrate during the deuterium plasma process S30, without supplying deuterium gas into the processing container 1 after the deuterium plasma process S30.

[0054] Based on the above examples, it can be said that the amount of deuterium introduced into the silicon nitride film can be controlled by changing the temperature of the substrate and performing heat treatment after the deuterium plasma process S30 without exposing the silicon nitride film to plasma.

[0055] The embodiments disclosed herein should be considered in all respects to be 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.

[0056] In the embodiments described above, the substrate processing apparatus is described as a batch-type apparatus that processes multiple substrates at once, but the disclosure is not limited thereto. For example, the substrate processing apparatus may be a single-wafer apparatus that processes substrates one at a time. [Explanation of Symbols]

[0057] S10 Preparation process S20 Temperature stabilization process S30 Deuterium Plasma Process S40 Concentration adjustment process

Claims

1. A process of housing a substrate having an insulating film on its surface inside a processing container, The process involves maintaining the substrate housed in the processing container at a first temperature, exposing the insulating film to a plasma generated from a gas containing deuterium gas, thereby introducing deuterium into the insulating film; A step of heat-treating the insulating film without exposing it to the plasma while controlling the substrate housed in the processing container to a second temperature different from the first temperature, thereby adjusting the concentration of deuterium introduced into the insulating film, A substrate processing method having the following characteristics.

2. The second temperature is determined based on a desired deuterium concentration. The substrate processing method according to claim 1.

3. The adjustment step includes supplying an inert gas into the processing container. The substrate processing method according to claim 1.

4. The second temperature is lower than the first temperature. The substrate processing method according to claim 1.

5. The adjustment step is carried out without supplying the deuterium gas into the processing container. The substrate processing method according to claim 4.

6. The second temperature is higher than the first temperature. The substrate processing method according to claim 1.

7. The adjustment step includes supplying the deuterium gas into the processing container. The substrate processing method according to claim 6.

8. The insulating film is a silicon nitride film. The substrate processing method according to claim 1.

9. Processing container and A gas supply unit that supplies gas into the processing container, A plasma generation unit that generates plasma from the aforementioned gas, Control unit and Equipped with, The control unit, A step of housing a substrate having an insulating film on its surface in the processing container, The process involves maintaining the substrate housed in the processing container at a first temperature, exposing the insulating film to a plasma generated from a gas containing deuterium gas, thereby introducing deuterium into the insulating film; A step of heat-treating the insulating film without exposing it to the plasma while controlling the substrate housed in the processing container to a second temperature different from the first temperature, thereby adjusting the concentration of deuterium introduced into the insulating film, The gas supply unit and the plasma generation unit are configured to be controlled to perform the following actions: Circuit board processing equipment.

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