Substrate processing method and substrate processing apparatus

Abstract

Even when performing COR treatment on the substrate at low temperatures, by-products remaining on the film during etching are effectively removed. [Solution] A substrate processing method for processing a substrate using a substrate processing apparatus, comprising the steps of: supplying a processing gas into a chamber to perform an etching process on the surface of a silicon oxide film on the substrate; vaporizing a liquid having OH groups under reduced pressure and spraying it onto the AFS layer deposited on the substrate in the etching process; and reducing the pressure inside the chamber to remove at least a portion of the decomposed AFS layer.

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses a substrate processing method including a step of storing a substrate having a silicon-containing film formed on a surface thereof in a processing container, a first step of supplying a processing gas containing a halogen-containing gas and a basic gas to the substrate in a state where the inside of the processing container is at a first pressure to alter the silicon-containing film to generate a reaction product, a second step of vaporizing the reaction product by setting the inside of the processing container to a second pressure lower than the first pressure, a repeating step of alternately repeating the first step and the second step, and a step of supplying the processing gas to the substrate on which the reaction product remains in the first step after the second time in the repeating step.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The technology according to the present disclosure effectively removes by-products remaining on a film during etching even when performing COR processing on a substrate at a low temperature.

Means for Solving the Problems

[0005] One aspect of the present disclosure is a substrate processing method for processing a substrate using a substrate processing apparatus, comprising the steps of: supplying a processing gas into a chamber to perform an etching process on the surface of a silicon oxide film on the substrate; vaporizing a liquid having OH groups under reduced pressure and spraying it onto the AFS layer deposited on the substrate in the etching process; and reducing the pressure inside the chamber to remove at least a portion of the decomposed AFS layer. [Effects of the Invention]

[0006] According to this disclosure, even when performing COR treatment on a substrate at a low temperature, by-products remaining on the film during etching can be effectively removed. [Brief explanation of the drawing]

[0007] [Figure 1] This is a longitudinal cross-sectional view showing a schematic configuration of the wafer processing apparatus according to this embodiment. [Figure 2] This is an explanatory diagram showing the mounting platform and partition wall at the wafer transport position. [Figure 3] This is an explanatory diagram showing the mounting platform and partition wall at the wafer processing location. [Figure 4] This is an explanatory diagram showing the process of AFS removal during high-temperature (90°C) COR treatment. [Figure 5] This is an explanatory diagram showing the process of AFS removal during low-temperature (35°C) COR treatment. [Figure 6] This is an explanatory diagram of the substrate processing method according to the present embodiment. [Figure 7] This is a schematic diagram illustrating the pattern of collapse. [Figure 8] This is a schematic diagram illustrating an example of the application of the substrate processing method according to this embodiment. [Figure 9] This is a schematic diagram illustrating the process of purging HF gas. [Figure 10] This is a schematic diagram illustrating the application of the substrate processing method according to the present invention to a low-temperature COR process, specifically when performing a purging treatment. [Modes for carrying out the invention]

[0008] Hereinafter, the wafer processing apparatus as a substrate processing apparatus and the wafer processing method as a substrate processing method according to this embodiment will be described with reference to the drawings. In this specification, elements having substantially the same functional configuration are denoted by the same reference numerals, and redundant explanations will be omitted.

[0009] <Wafer Processing Equipment> Figure 1 is a longitudinal cross-sectional view showing a schematic configuration of the wafer processing apparatus 1 according to this embodiment. In this embodiment, the case in which the wafer processing apparatus 1 is a COR (Chemical Oxide Removal) processing apparatus that performs COR processing on a wafer W as a substrate will be described.

[0010] As shown in Figure 1, the wafer processing apparatus 1 includes a chamber 10 that is airtightly configured to house a wafer W, a plurality of mounting platforms 11a and 11b in the chamber 10 on which the wafer W is placed, two mounting platforms 11a and 11b in this embodiment, lifting mechanisms 12a and 12b that independently raise and lower each mounting platform 11a and 11b, a gas supply unit 13 that supplies processing gas from above each mounting platform 11a and 11b toward the mounting platforms 11a and 11b, inner walls 14a and 14b fixed to the bottom of the chamber 10 and individually surrounding the outside of each mounting platform 11a and 11b, a partition wall 15 that surrounds the outside of each mounting platform 11a and 11b and is configured to be able to move up and down, a lifting mechanism 16 that raises and lowers the partition wall 15, and an exhaust unit 17 that exhausts the inside of the chamber 10.

[0011] The chamber 10 is a container that is generally formed of a metal such as aluminum or stainless steel and has a substantially rectangular parallelepiped shape as a whole. The chamber 10 has a cylindrical side wall 20 whose shape in plan view is, for example, substantially rectangular, and whose upper and lower surfaces are open, a ceiling plate 21 that hermetically covers the upper surface of the side wall 20, and a bottom plate 22 that covers the lower surface of the side wall 20. Also, a seal member (not shown) for keeping the inside of the chamber 10 airtight is provided between the upper end surface of the side wall 20 and the ceiling plate 21. Further, a heater (not shown) is provided in the chamber 10, and a heat insulating material (not shown) is provided on the bottom plate 22. Furthermore, the inside of the chamber 10 may be coated with a protective member.

[0012] The mounting tables 11a and 11b are formed in a substantially cylindrical shape and have stages 30a and 30b provided with mounting surfaces for mounting the wafer W, and support portions 31a and 31b for supporting the stages 30a and 30b. The upper sides of the stages 30a and 30b are configured as electrostatic chucks and adsorb and hold the wafer W placed on the mounting surfaces of the stages 30a and 30b.

[0013] Inside the stages 30a and 30b, temperature adjustment mechanisms 32a and 32b for adjusting the temperatures of the stages 30a and 30b and the wafer W placed on the stages 30a and 30b are provided. The temperature adjustment mechanisms 32a and 32b are provided in the respective stages 30a and 30b and independently adjust the temperatures of the stages 30a and 30b. The temperature adjustment mechanisms 32a and 32b have heaters 33a and 33b and flow paths 34a and 34b through which a refrigerant circulates.

[0014] A power supply (not shown) is connected to the heaters 33a and 33b. By supplying power from the power supply to the heaters 33a and 33b, the temperatures of the stages 30a and 30b are adjusted. For example, the power supply may be common to the heaters 33a and 33b, and the control unit 100 described later may individually control the power from the power supply to the heaters 33a and 33b. Alternatively, individual power supplies may be connected to the heaters 33a and 33b. Note that the adjustment range of the temperatures of the stages 30a and 30b by the heaters 33a and 33b is arbitrary, but is, for example, 0.1°C.

[0015] Chillers (not shown) are connected to the flow paths 34a and 34b. Refrigerant adjusted to a desired temperature from the chillers is supplied to the flow paths 34a and 34b and circulates through the flow paths 34a and 34b to adjust the temperatures of the stages 30a and 30b. For example, the chillers may be individually connected to the flow paths 34a and 34b.

[0016] The support parts 31a and 31b support the lower parts of the stages 30a and 30b. The support parts 31a and 31b have a hollow structure, and a sealed space (not shown) surrounded by the interiors of the support parts 31a and 31b and the lower surfaces of the stages 30a and 30b is formed. A support pin unit (not shown) that is driven vertically is provided in the sealed space. By inserting the support pins of the support pin unit through the through-holes of the stages 30a and 30b and moving up and down, the wafer W is transferred between the stages 30a and 30b and a transfer mechanism (not shown) provided outside the wafer processing apparatus 1.

[0017] The elevating mechanisms 12a and 12b are provided on the respective mounting tables 11a and 11b and independently raise and lower the mounting tables 11a and 11b. For this reason, the mounting tables 11a and 11b can independently adjust their heights. The adjustment range of the heights of the mounting tables 11a and 11b by the elevating mechanisms 12a and 12b is arbitrary, but for example, it is 1 mm.

[0018] When the elevating mechanisms 12a and 12b raise the mounting tables 11a and 11b (stages 30a and 30b) to the wafer processing position at a desired height, processing is performed on the wafer W placed on the mounting tables 11a and 11b. Further, when the mounting tables 11a and 11b (stages 30a and 30b) are lowered to the wafer transfer position by the elevating mechanisms 12a and 12b, the wafer W lifted from the upper surfaces of the mounting tables 11a and 11b by the above-described support pin unit can be accessed from outside the chamber 10.

[0019] The lifting mechanisms 12a and 12b each have drive units 40a and 40b located outside the chamber 10, and drive shafts 41a and 41b that connect the drive units 40a and 40b to the lower surfaces of the support units 31a and 31b, and extend vertically upward through the bottom plate 22 of the chamber 10. Actuators, for example, are used for the drive units 40a and 40b.

[0020] Inside the chamber 10, bellows 42a and 42b are provided that can extend and retract vertically, surrounding the drive shafts 41a and 41b. The upper ends of the bellows 42a and 42b are airtightly connected to the lower surfaces of the support parts 31a and 31b, and the lower ends of the bellows 42a and 42b are airtightly connected to the upper surface of the bottom plate 22. Therefore, when the mounting tables 11a and 11b are raised and lowered via the drive shafts 41a and 41b, the bellows 42a and 42b extend and retract vertically, thereby maintaining airtightness inside the chamber 10.

[0021] The gas supply unit 13 has a shower head 50 that supplies processing gas to wafers W placed on mounting tables 11a and 11b. The shower head 50 is individually provided on the lower surface of the ceiling plate 21 of the chamber 10, facing each mounting table 11a and 11b. The shower head 50 has, for example, a substantially cylindrical frame 51 with an open bottom and supported on the lower surface of the ceiling plate 21, and a substantially disc-shaped shower plate 52 fitted into the inner surface of the frame 51. It is preferable that the shower plate 52 has a diameter at least larger than the diameter of the wafer W in order to uniformly supply processing gas to the entire surface of the wafer W placed on the mounting tables 11a and 11b. The shower plate 52 is also provided at a predetermined distance from the ceiling portion of the frame 51. As a result, a space 53 is formed between the ceiling portion of the frame 51 and the upper surface of the shower plate 52. The shower plate 52 is also provided with a plurality of openings 54 that penetrate through the shower plate 52 in the thickness direction.

[0022] A gas supply source 56 is connected to the space 53 between the ceiling of the frame 51 and the shower plate 52 via a gas supply pipe 55. The gas supply source 56 is configured to supply, for example, fluorine (F2) gas, hydrogen fluoride (HF) gas, or ammonia (NH3) gas as a processing gas, or argon (Ar) gas as a diluent or purge gas. The gas supply source 56 may also be configured to vaporize and supply a liquid having OH groups (for example, H2O) to the wafer W. The gas supplied from the gas supply source 56 is uniformly supplied to the wafer W placed on the mounting tables 11a and 11b via the space 53 and the shower plate 52. The gas supply pipe 55 is also provided with a flow rate adjustment mechanism 57 to adjust the amount of processing gas supplied, and is configured to individually control the amount of processing gas supplied to each wafer W. The shower head 50 may be a post-mix type that can supply multiple types of processing gases individually without mixing them.

[0023] Each inner wall 14a, 14b has a substantially cylindrical main body portion 60a, 60b and flange portions 61a, 61b provided at the upper ends of the main body portion 60a, 60b, which project horizontally toward the outer circumference of the inner wall 14a, 14b. The inner walls 14a, 14b are arranged to individually surround the support portions 31a, 31b of the mounting bases 11a, 11b and the bellows 42a, 42b of the lifting mechanisms 12a, 12b. The inner diameter of the main body portion 60a, 60b of the inner walls 14a, 14b is set to be larger than the outer diameter of the support portions 31a, 31b and the bellows 42a, 42b, and exhaust spaces V are formed between the inner walls 14a, 14b and the support portions 31a, 31b and the bellows 42a, 42b, respectively.

[0024] Multiple slits (not shown) are formed at the lower ends of the inner walls 14a and 14b. The slits are exhaust ports through which the processed gas is discharged. In this embodiment, the slits are formed at approximately equal intervals along the circumferential direction of the inner walls 14a and 14b.

[0025] The partition wall 15 has two cylindrical sections 70a and 70b that individually surround the two mounting bases 11a and 11b, an upper flange section 71 provided at the upper ends of the cylindrical sections 70a and 70b, and a lower flange section 72 provided at the lower ends of the cylindrical sections 70a and 70b. The inner diameter of the cylindrical sections 70a and 70b is set to be larger than the outer surface of the mounting bases 11a and 11b, so that a gap is formed between the cylindrical sections 70a and 70b and the mounting bases 11a and 11b.

[0026] In one embodiment, heaters (not shown) are provided in the cylindrical portions 70a and 70b of the partition wall 15, and are heated to, for example, 100°C to 150°C. This heating prevents foreign matter contained in the processing gas from adhering to the partition wall 15.

[0027] As shown in Figure 1, a sealing member 73, such as an O-ring, is provided on the upper surface of the upper flange portion 71. The sealing member 73 airtightly seals the space between the upper flange portion 71 and the frame 51 when the partition wall 15 is raised to the wafer processing position by the lifting mechanism 16 and the frame 51 comes into contact with it. A sealing member 73 is provided on each of the mounting tables 11a and 11b. By raising the partition wall 15 and bringing the frame 51 into contact with the sealing member 73, a processing space S is formed, surrounded by the mounting tables 11a and 11b, the partition wall 15, and the shower head 50.

[0028] Furthermore, when the partition wall 15 is lowered to the wafer transport position by the lifting mechanism 16, the wafer W, which has been lifted from the upper surfaces of the mounting tables 11a and 11b by the support pin unit described above, becomes accessible from outside the chamber 10.

[0029] The lifting mechanism 16 raises and lowers the bulkhead 15. The lifting mechanism 16 has a drive unit 80 located outside the chamber 10, a drive shaft 81 connected to the drive unit 80 and extending vertically upward inside the chamber 10 through the bottom plate 22 of the chamber 10, and a plurality of guide shafts 82, the tip of which is connected to the bulkhead 15 and the other end which extends outside the chamber 10. For example, an actuator is used for the drive unit 80. The guide shafts 82 prevent the bulkhead 15 from tilting when the bulkhead 15 is raised and lowered by the drive shaft 81.

[0030] The lower end of the extendable bellows 83 is airtightly connected to the drive shaft 81. The upper end of the bellows 83 is airtightly connected to the lower surface of the bottom plate 22. Therefore, when the drive shaft 81 moves up and down, the bellows 83 extends and retracts along the vertical direction, maintaining airtightness inside the chamber 10. A sleeve (not shown), for example, fixed to the bottom plate 22, is provided between the drive shaft 81 and the bellows 83 to function as a guide during the up and down movement.

[0031] A bellows 84, which is extendable and retractable, is connected to the guide shaft 82, similar to the drive shaft 81. The upper end of the bellows 84 is airtightly connected to both the bottom plate 22 and the side wall 20, spanning across both. Therefore, when the guide shaft 82 moves up and down in conjunction with the raising and lowering movement of the partition wall 15 by the drive shaft 81, the bellows 84 extends and retracts vertically, thereby maintaining airtightness inside the chamber 10. In addition, a sleeve (not shown) that functions as a guide during the raising and lowering movement is provided between the guide shaft 82 and the bellows 84, similar to the case of the drive shaft 81.

[0032] Furthermore, since the upper end of the bellows 84 is the fixed end and the lower end of the bellows 84 connected to the guide shaft 82 is the free end, when negative pressure is created inside the chamber 10, a force acts to compress the bellows 84 vertically due to the pressure difference between the inside and outside of the bellows 84. As a result, the guide shaft 82 connected to the free end of the bellows 84 rises vertically upward as the bellows 84 contracts. This causes the partition wall 15 to rise evenly, ensuring proper contact between the sealing member 73 and the frame 51, thereby ensuring a seal between the partition wall 15 and the frame 51. Similarly, by ensuring proper contact between the sealing member 74 and the flange portions 61a and 61b, a seal between the partition wall 15 and the flange portions 61a and 61b can be ensured. Furthermore, the guide shaft 82 is subjected to downward forces due to the reaction force from the bellows 84, which acts as an elastic member, and the weight of the guide shaft 82 itself. However, the differential pressure acting on the guide shaft 82 can be adjusted by appropriately setting the diameter of the bellows 84.

[0033] The exhaust section 17 includes an exhaust mechanism 90 for exhausting air from inside the chamber 10, and an exhaust port 91 provided on the bottom plate 22 of the chamber 10, outside the partition wall 15. That is, the exhaust port 91 is provided on the bottom plate 22 outside the partition wall 15, at a position that does not overlap with the partition wall 15 in a plan view. The exhaust port 91 is in communication with the exhaust pipe 92.

[0034] These exhaust mechanisms 90, exhaust ports 91, and exhaust pipes 92 are shared by the two processing spaces S. That is, the two processing spaces S communicate with a common exhaust space V formed at the bottom of the chamber 10, and the processed gas flowing out into this exhaust space V is discharged by the exhaust mechanism 90 via the common exhaust pipe 92. The exhaust pipe 92 is equipped with a control valve 93 for adjusting the amount of exhaust by the exhaust mechanism 90. In addition, the ceiling plate 21 is equipped with a pressure measuring mechanism (not shown) for measuring the pressure in each of the processing spaces S of the mounting platforms 11a and 11b. The opening of the control valve 93 is controlled, for example, based on the measurement value from this pressure measuring mechanism.

[0035] The wafer processing apparatus 1 described above is provided with at least one control unit 100. The control unit 100 processes computer-executable instructions that cause the wafer processing apparatus 1 to perform the various processes described herein. The control unit 100 may be configured to control each element of the wafer processing apparatus 1 to perform the various processes described herein. In one embodiment, some or all of the control unit 100 may be included in the wafer processing apparatus 1. The control unit 100 may include a processing unit, a storage unit, and a communication interface. The control unit 100 is implemented, for example, by a computer. The processing unit may be configured to read a program from the storage unit that provides logic or routines that enable various control operations, and to perform various control operations by executing the read program. This program may be stored in the storage unit in advance, or it may be retrieved via a medium when needed. The retrieved program is stored in the storage unit and read from the storage unit and executed by the processing unit. The medium may be various storage media readable by a computer, or it may be a communication line connected to a communication interface. The storage medium may be temporary or non-temporary. The processing unit may be a CPU (Central Processing Unit), or it may be one or more circuits. The storage unit may include RAM (Random Access Memory), ROM (Read Only Memory), HDD (Hard Disk Drive), SSD (Solid State Drive), or a combination thereof. The communication interface may communicate with the wafer processing device 1 via a communication line such as a LAN (Local Area Network).

[0036] <Wafer Processing Method> Next, we will explain the wafer processing (COR processing) in the wafer processing apparatus 1 configured as described above.

[0037] First, as shown in Figure 2, the mounting stages 11a and 11b are lowered to the wafer transport positions P1a and P1b. At the wafer transport positions P1a and P1b, the height of the upper surfaces (mounting surfaces) of the stages 30a and 30b of the mounting stages 11a and 11b is the same. The partition wall 15 is also lowered to the wafer transport position. With the mounting stages 11a and 11b and the partition wall 15 in this position, the wafer W is transported into the chamber 10 by a transport mechanism (not shown) provided outside the wafer processing apparatus 1 and placed on the mounting stages 11a and 11b.

[0038] Next, as shown in Figure 3, the partition wall 15 rises to the wafer processing position. This creates a processing space S for each mounting table 11a, 11b, enclosed by the mounting tables 11a, 11b, the partition wall 15, and the shower head 50.

[0039] Furthermore, as shown in Figure 3, the mounting stages 11a and 11b rise to the wafer processing positions P2a and P2b. The stages 30a and 30b and the wafers W placed on them are adjusted to a desired temperature by the temperature control mechanisms 32a and 32b. The desired temperature is, for example, -20°C to 250°C, mainly -10°C to 120°C. By adjusting the temperatures of these wafer processing positions P2a and P2b and stages 30a and 30b (wafers W), the etching amount on the wafers W at each stage 30a and 30b is individually controlled.

[0040] Next, the exhaust unit 17 exhausts the inside of the chamber 10 to the desired pressure, and the gas supply unit 13 supplies the processing gas into the inside of the chamber 10, performing COR processing on the wafers W placed on the mounting tables 11a and 11b. The processing gas in the processing space S passes through the exhaust space V and the slits in the inner walls 14a and 14b, and is discharged from the exhaust unit 17.

[0041] In this embodiment, the heights of stages 30a and 30b are adjusted before the COR treatment, but the heights of stages 30a and 30b are not changed during the COR treatment.

[0042] Next, once the COR process is complete, the mounting tables 11a and 11b descend to the wafer transport positions P1a and P1b, and the partition wall 15 also descends to the wafer transport position. Subsequently, the wafers W on the mounting tables 11a and 11b are transported out of the wafer processing device 1 by a transport mechanism (not shown). This completes the series of COR processes.

[0043] In the COR treatment in the wafer processing apparatus 1, a processing gas is supplied to the surface of the oxide film (silicon oxide film), causing a chemical reaction between the oxide film and the processing gas to alter the oxide film and generate reaction products. Subsequently, the wafer W may be subjected to PHT (Post Heat Treatment) by a heating device provided outside the wafer processing apparatus 1. In the PHT treatment, the wafer W is heated, and the reaction products generated by the COR treatment are vaporized and removed. In one embodiment, etching of the oxide film is performed by performing these COR treatment and PHT treatments in succession.

[0044] <High-temperature COR treatment and low-temperature COR treatment> As described above, the COR process in the wafer processing apparatus 1 according to this embodiment is performed when the temperature of the wafer W is set to, for example, -20°C to 250°C, mainly -10°C to 120°C. When the process performed when the temperature of the wafer W is approximately 60°C to 70°C or higher is called high-temperature COR processing, and the process performed below the temperature of high-temperature COR processing is called low-temperature COR processing, each process has the following characteristics.

[0045] When etching is performed on the surface of an oxide film (silicon oxide film) by supplying HF / NH3 as a processing gas, a solid-phase by-product (reaction product) called AFS (Ammonium fluorosilicate, (NH4)2[SiF6]) is generated. Since this AFS is thermally decomposable, it can be removed by, for example, the PHT treatment described in the wafer processing method above, or by performing a COR treatment at a high temperature and reducing the pressure (e.g., below 10 mT).

[0046] Figure 4 is an explanatory diagram of the process of AFS removal in high-temperature (90°C) COR treatment, and the treatment is performed in the order of (a) to (f). Starting from Figure 4(a), (b) is the first etching treatment, (c) is the first vacuum treatment, (d) is the second etching treatment, (e) is the second vacuum treatment, and (f) is the PHT treatment after the completion of the COR treatment.

[0047] In high-temperature COR processing, when the oxide film (silicon oxide film) 110 formed on the wafer W shown in Figure 4(a) is etched for the first time, an AFS layer 120, a by-product, is deposited on the oxide film 110 as shown in Figure 4(b). Here, the deposited AFS layer 120 sublimes due to the high temperature and can be removed by vacuum processing as shown in Figure 4(c). Similarly, in the second etching process, the deposited AFS layer 120 is removed by vacuum processing as shown in Figures 4(d) and (e).

[0048] The deposited AFS layer 120 inhibits etching. In the high-temperature COR treatment shown in Figure 4, the AFS layer 120 generated and deposited by the etching process is easily removed, making it possible to obtain a large etching amount (EA) and achieve good throughput.

[0049] Figure 5 is an explanatory diagram of the process of AFS removal in low-temperature (35°C) COR treatment, and the treatment is performed in the order of (a) to (f). Starting from Figure 5(a), (b) is the first etching treatment, (c) is the first vacuum treatment, (d) is the second etching treatment, (e) is the second vacuum treatment, and (f) is the PHT treatment after the completion of the COR treatment.

[0050] In low-temperature COR processing, as shown in Figure 5, the AFS layer 120 deposited by etching the oxide film 110 formed on the wafer W remains almost completely intact during the COR process. That is, in low-temperature COR processing, the AFS layer 120 is difficult to remove because it does not sublimate easily, and therefore a large amount of etching cannot be obtained. However, because the AFS layer 120 has the characteristic of being easily deposited, process controllability such as seam resistance (suppression of the occurrence of seams, defects, etc.) and in-plane uniformity is good.

[0051] In low-temperature COR processing, to obtain a large etching amount, one can employ a method of performing PHT processing at a predetermined timing to remove the AFS layer 120, and then returning to low-temperature COR processing. However, this method has the drawback of significantly reducing throughput.

[0052] <Substrate processing method according to this embodiment> Since the AFS layer 120 is a salt composed of [SiF6](-2) and 2(NH4)(+2), it is soluble in water, just like other common salts. On the other hand, the poor sublimation of the AFS layer 120 is due to the strong ionic bond between [SiF6] and (NH4), and it is difficult to provide enough energy to decompose it by means other than heat, similar to how NaCl is difficult to decompose by heat.

[0053] As described above, low-temperature COR processing has the characteristic of easily depositing the AFS layer 120, resulting in good process controllability such as seam resistance and in-plane uniformity. Therefore, in the substrate processing method according to this embodiment, a technique described below was devised to achieve a large etching amount and high throughput when performing low-temperature COR processing with good process controllability in a temperature range in which the AFS layer 120 does not sublimate.

[0054] Figure 6 is an explanatory diagram of the substrate processing method according to this embodiment, illustrating the process of AFS removal in low-temperature (35°C) COR processing in the order of (a) to (f). Starting from Figure 6(a), (b) is the first etching process, (c) is the first vacuum processing, (d) is the second etching process, (e) is the second vacuum processing, and (f) is the PHT processing after the completion of COR processing.

[0055] In the substrate processing method according to this embodiment, when the oxide film (silicon oxide film) 110 formed on the wafer W shown in Figure 6(a) is etched for the first time, an AFS layer 120, which is a by-product, is deposited on the oxide film 110 as shown in Figure 6(b). Then, with the AFS layer 120 deposited on the oxide film 110 after the first etching process, a process (purging process) is performed in which vaporized water (H2O) is sprayed under reduced pressure. In this purging process, an inert gas such as Ar may be supplied along with water.

[0056] The AFS layer 120 is a salt composed of [SiF6](-2) and 2(NH4)(+2), which is soluble in water and H + and OH - It can be decomposed by this process, and as shown in Figure 6(c), it can be removed to some extent (at least partially) by decomposition and sublimation even at low temperatures under reduced pressure.

[0057] Similarly, in the second etching process, the deposited AFS layer 120 is removed to some extent by applying vaporized water (H2O) under reduced pressure (purging process) as shown in Figures 6(d) and (e).

[0058] The expected response in the above Purge process is as follows: (NH4)2[+2]·SiF6[-2]+2H2O →(NH4)2[+2]·SiF6[-2]+2H[+2]+2OH[-2] →(NH4)2·2OH[±0]+SiF6·H2[±0] →2(NH4·OH)+SiF6·H2 →2NH3+2H2O+SiF4+2HF

[0059] Furthermore, the temperature and flow rate of the water used in the purging process (where vaporized water (H2O) is sprayed under reduced pressure) are arbitrary. For example, increasing the flow rate is expected to improve process controllability and achieve high throughput.

[0060] Although this explanation assumes that purging is performed after both the first and second etching processes, it is also acceptable to perform purging after at least one etching process (for example, only after the second etching process).

[0061] <Avoiding pattern collapse> As described above, when HF / NH3 is supplied as a processing gas to the surface of an oxide film (silicon oxide film) and etching is performed, the AFS layer 120 is generated as a by-product (reaction product). When pattern formation is performed by etching, if the amount of etching per step is large, a large amount of AFS layer 120 will be generated, and there is a risk that the pattern will collapse when it is removed by PHT treatment.

[0062] Figure 7 is a schematic diagram illustrating the collapse of a pattern, showing the process of removing the AFS layer 120 deposited on pattern P1 by PHT treatment. As shown in Figures 7(a) and (b), when the AFS layer 120 is deposited by etching to fill the gaps between patterns, the PHT treatment causes the AFS layer 120 to sublimate. At that time, as shown in Figures 7(c) to (e), there is a risk that the pattern may collapse due to the stress (arrows in the figure) during the sublimation of the AFS layer 120.

[0063] On the other hand, if the substrate processing method according to this embodiment is applied, the removal of the AFS layer 120 deposited on the pattern P2 can be performed without causing pattern collapse. FIG. 8 is a schematic explanatory diagram showing an application example of the substrate processing method according to this embodiment. As shown in FIGS. 8(a) and (b), when the AFS layer 120 is deposited so as to fill the spaces between the patterns on the pattern P2, the cycle can be repeated while performing the Purge process as shown in FIG. 8(c). In this case, the AFS layer 120 can be gently removed by the Purge process, and gaps can be created between the patterns as shown in FIGS. 8(d) and (e). Thereby, pattern collapse as shown in FIG. 7 can be avoided.

[0064] <Comparison with HF Purge Process> As a post-treatment method when HF / NH3 is supplied as a processing gas to the surface of the oxide film (silicon oxide film) in the low-temperature COR process and etching is performed, a process of purging HF gas can be considered. FIG. 9 is a schematic explanatory diagram of the process of purging HF gas (HF Purge process). Starting from (a), (b) represents the etching process, (c) represents the HF Purge process, and (d) represents the PHT process after the COR process is completed.

[0065] When etching is performed on the oxide film (silicon oxide film) 110 formed on the wafer W shown in FIG. 9(a), an AFS layer 120 as a by-product is deposited on the oxide film 110 as shown in FIG. 9(b). Then, by performing the HF Purge process as shown in FIG. 9(c), the water present in the AFS layer 120 serves as a catalyst and the etching further proceeds. The removal of the deposited AFS layer 120 as shown in FIG. 9(d) is performed by the PHT process.

[0066] The assumed reactions in the above HF Purge process are as follows. SiO2 + HF + NH3 → AFS ((NH4)2[SiF6]) + H2O SiO2 + AFS + H2O + HF → AFS + SiF X + nH2O

[0067] In contrast, Figure 10 is a schematic diagram illustrating the application of the substrate processing method according to the present invention when HF / NH3 is supplied as a processing gas to the surface of an oxide film (silicon oxide film) in a low-temperature COR treatment and etching is performed, and when purging treatment of vaporized water (H2O) is performed. Starting from Figure 10(a), (b) refers to the etching treatment, (c) to the purging treatment, and (d) to the PHT treatment after the completion of the COR treatment.

[0068] As shown in Figure 10(a), when an etching process is performed on the oxide film (silicon oxide film) 110 formed on the wafer W, an AFS layer 120, a by-product, is deposited on the oxide film 110 as shown in Figure 10(b). Then, as shown in Figure 10(c), by performing a purging process, the AFS layer 120 is partially decomposed and sublimated even at low temperatures under reduced pressure, thereby accelerating its removal. Finally, as shown in Figure 10(d), the deposited AFS layer 120 is removed by a PHT process.

[0069] As can be seen by comparing Figures 9 and 10, different post-treatment methods are proposed for etching the surface of an oxide film (silicon oxide film) by supplying HF / NH3 during low-temperature COR processing. While HF purging treatment has the characteristic of etching progressing during the process, purging with vaporized water (H2O) allows for gradual decomposition and removal of the AFS layer 120 without significantly advancing etching. Various methods can be adopted depending on the required etching amount, process controllability, throughput, etc.

[0070] <Effects and Effects of the Technology Disclosed in This Disclosure> According to the substrate processing method of this embodiment described above, when performing low-temperature COR processing with good process controllability in a temperature range in which the AFS layer 120 does not sublimate, a large etching amount and high throughput can be achieved. In other words, even when performing low-temperature COR processing on the substrate, by-products remaining on the film during etching can be effectively removed.

[0071] For example, if the PHT treatment after COR treatment can be eliminated, COR treatment can be applied to products that generally require strict control of their thermal history, such as resists and wafers W after ion implantation. In addition, the decomposition of the AFS layer 120 using the purging treatment of vaporized water (H2O) is gradual compared to the rapid sublimation of the AFS layer 120 by heating, thus avoiding or reducing phenomena such as pattern collapse that occur during the sublimation of the AFS layer 120, which is a problem when heating.

[0072] The embodiments disclosed herein should be considered in all respects as illustrative and not restrictive. The embodiments described above may be omitted, replaced, or modified in various ways without departing from the scope and spirit of the appended claims. For example, the constituent elements of the embodiments described above can be combined in any way. Such any combination will naturally yield the functions and effects of each constituent element in the combination, as well as other functions and effects that will be apparent to those skilled in the art from the description herein.

[0073] Furthermore, the effects described herein are merely descriptive or illustrative and not limiting. In other words, the technology relating to this disclosure may produce other effects that are obvious to those skilled in the art from the description herein, in addition to or instead of the effects described herein.

[0074] For example, in the above embodiment, the case in which HF / NH3 is supplied as a processing gas to the surface of an oxide film (silicon oxide film) and etching is performed was described as an example, but the scope of application of the present invention is not limited to this. That is, it can also be applied to silicon etching treatment using fluorine (F2) gas and ammonia (NH3) gas.

[0075] Furthermore, although the gas used in the purging process was described as vaporized water (H2O), any gas capable of decomposing the salt consisting of [SiF6](-2) and 2(NH4)(+2) in the AFS layer 120 is acceptable, for example, a vaporized liquid containing an OH group.

[0076] Furthermore, the following configuration examples also fall within the technical scope of this disclosure. (1) A substrate processing method for processing a substrate using a substrate processing apparatus, The process involves supplying a processing gas into a chamber to perform an etching process on the surface of the silicon oxide film on the substrate, The etching process involves a step of vaporizing a liquid having OH groups under reduced pressure and spraying it onto the AFS layer deposited on the substrate, A substrate processing method comprising the steps of reducing the pressure inside a chamber and removing at least a portion of the decomposed AFS layer. (2) The substrate processing method according to (1), wherein the etching process is a low-temperature COR process performed at a temperature of less than 70°C. (3) The substrate processing method according to (1) or (2), wherein the processing gas is HF / NH3. (4) The substrate processing method according to any one of (1) to (3), wherein the liquid having the OH group is H2O. (5) A substrate processing apparatus for processing substrates, The substrate processing apparatus includes a control unit, The control unit, The process involves supplying a processing gas into a chamber to perform an etching process on the surface of the silicon oxide film on the substrate, The etching process involves a step of vaporizing a liquid having OH groups under reduced pressure and spraying it onto the AFS layer deposited on the substrate, A substrate processing apparatus that includes a step of reducing the pressure inside the chamber and removing at least a portion of the decomposed AFS layer. [Explanation of symbols]

[0077] 1. Wafer processing equipment 10 Chambers 110 Oxide film (silicon oxide film) 120 AFS layers W wafer

Claims

1. A substrate processing method for processing a substrate using a substrate processing apparatus, The process involves supplying a processing gas into a chamber to perform an etching process on the surface of the silicon oxide film on the substrate, The etching process involves a step of vaporizing a liquid having OH groups under reduced pressure and spraying it onto the AFS layer deposited on the substrate, A substrate processing method comprising the steps of reducing the pressure inside a chamber and removing at least a portion of the decomposed AFS layer.

2. The substrate processing method according to claim 1, wherein the etching process is a low-temperature COR process performed at a temperature of less than 70°C.

3. The aforementioned processing gas is HF / NH ３ The substrate processing method according to claim 1.

4. The liquid having the OH group is H ２ The substrate processing method according to claim 1, wherein the value is O.

5. A substrate processing apparatus for processing substrates, The substrate processing apparatus includes a control unit, The control unit, The process involves supplying a processing gas into a chamber to perform an etching process on the surface of the silicon oxide film on the substrate, The etching process involves a step of vaporizing a liquid having OH groups under reduced pressure and spraying it onto the AFS layer deposited on the substrate, A substrate processing apparatus that includes a step of reducing the pressure inside the chamber and removing at least a portion of the decomposed AFS layer.

Images