SUBSTRATE PROCESSING APPARATUS AND SUBSTRATE PROCESSING METHOD
The substrate processing apparatus addresses inefficiencies in etching fine patterns by rotating substrates at high acceleration and deceleration rates, generating vortices to enhance fluid movement and improve etching efficiency in narrow gaps.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-08-27
- Publication Date
- 2026-03-11
AI Technical Summary
Conventional methods struggle to efficiently perform etching on substrates with fine patterns due to differences in fluid behavior on the substrate, leading to inadequate removal of etching targets in minute gaps.
A substrate processing apparatus that rotates the substrate at high acceleration and deceleration rates, controlled by a substrate rotation unit, to generate vortices within gaps as narrow as 20 nm or less, using etching liquids with reduced surface tension.
Improves the efficiency of removing etching targets in minute gaps by generating vortices that enhance fluid movement, effectively etching even in gaps as narrow as 10 nm or less.
Smart Images
Figure 2026042559000001_ABST
Abstract
Description
[Technical Field]
[0001] The present invention relates to a technique for supplying an etching liquid to a substrate to perform etching. [Background technology]
[0002] 2. Description of the Related Art Conventionally, various processes have been performed on a substrate by supplying a processing liquid to the substrate. In many cases, the substrate is rotated after or while the processing liquid is being supplied onto the substrate.
[0003] In the apparatus of Patent Document 1, the wafer (substrate) to be processed has a pattern portion extending in a direction intersecting the tangent direction of rotation. In this apparatus, a processing liquid is supplied to the wafer, the wafer is rotated forward, and then rotated backward to remove the sidewall film on both sides of the pattern portion. [Prior art documents] [Patent documents]
[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-272988 Summary of the Invention [Problem to be solved by the invention]
[0005] However, when the pattern on the substrate becomes finer, the behavior of the fluid on the substrate in response to acceleration differs from that of the conventional method, making it impossible to perform sufficient etching.
[0006] The present invention has been made in view of the above-mentioned problems, and has as its object to improve the efficiency of removing an etching target in a minute gap. [Means for solving the problem]
[0007] A first aspect of the present invention is a substrate processing apparatus that supplies an etching liquid to a substrate to perform etching, comprising: a substrate holding unit that holds the substrate in a horizontal position; a substrate rotation unit that rotates the substrate together with the substrate holding unit around a vertical axis; a processing liquid supply unit that supplies etching liquid to the surface of the substrate held by the substrate holding unit; and a control unit that controls the rotation of the substrate by the substrate rotation unit and the supply of etching liquid from the processing liquid supply unit, wherein an etching target on the substrate is present within a gap having a width of 20 nm or less, and under the control of the control unit, the substrate rotation unit repeatedly accelerates and decelerates the rotation of the substrate at a rotational acceleration of 3000 rpm / s or more while etching liquid is present on the substrate.
[0008] A second aspect of the present invention is a substrate processing apparatus according to the first aspect, wherein, under the control of the control unit, the substrate rotation unit repeatedly accelerates and decelerates the rotation of the substrate at a rotational acceleration of 6000 rpm / s or more while an etching solution is present on the substrate.
[0009] A third aspect of the present invention is the substrate processing apparatus of the first aspect (which may be the first or second aspect), wherein the etching target is present in a gap having a width of 10 nm or less.
[0010] A fourth aspect of the present invention is the substrate processing apparatus of the first aspect (which may be any one of the first to third aspects), wherein the gap extends in a direction perpendicular to the surface of the substrate.
[0011] A fifth aspect of the present invention is a substrate processing apparatus according to the first aspect (which may be any one of the first to third aspects), wherein the gap extends from a plane perpendicular to the surface of the substrate in a direction parallel to the surface of the substrate, the etching target is present both inside and outside the gap, and etching by the etching solution proceeds from outside the gap to inside the gap.
[0012] A sixth aspect of the present invention is the substrate processing apparatus of the fifth aspect, wherein the acceleration and deceleration of the rotation of the substrate are repeated under the control of the control unit at least while etching is being performed in the gap.
[0013] A seventh aspect of the present invention is the substrate processing apparatus of the fifth aspect (which may be the fifth or sixth aspect), wherein when etching is performed in the gap, a low surface tension liquid is mixed into the etching liquid under the control of the control unit.
[0014] An eighth aspect of the present invention is the substrate processing apparatus of the first aspect (which may be any one of the first to seventh aspects), wherein the etching target is TiN, TaN, LaO, TiAlC, TiAl, W or TiNOC.
[0015] A ninth aspect of the present invention is the substrate processing apparatus of any one of the first to eighth aspects, wherein the substrate rotating unit includes a vacuum chuck that holds the lower surface of the substrate.
[0016] A tenth aspect of the present invention is a substrate processing apparatus that supplies an etching liquid to a substrate to perform etching, comprising: a substrate holding unit that holds the substrate in a horizontal position; a substrate rotation unit that rotates the substrate together with the substrate holding unit around an axis facing vertically; a processing liquid supply unit that supplies etching liquid to the surface of the substrate held by the substrate holding unit; and a control unit that controls the rotation of the substrate by the substrate rotation unit and the supply of etching liquid from the processing liquid supply unit; wherein the etching target of the substrate is present within a gap having a width of 20 nm or less, and under the control of the control unit, the substrate rotation unit repeatedly accelerates and decelerates the rotation of the substrate while etching liquid is present on the substrate, thereby generating a vortex within the gap during etching, centered on an axis perpendicular to the depth direction of the gap.
[0017] An eleventh aspect of the present invention is a substrate processing method for supplying an etching solution to a substrate to perform etching, comprising the steps of holding the substrate in a horizontal position, with the etching target present within a gap having a width of 20 nm or less, and rotating the substrate around an axis facing vertically; supplying the etching solution to the surface of the substrate; and repeatedly accelerating and decelerating the rotation of the substrate at a rotational acceleration of 3000 rpm / s or more while the etching solution is present on the substrate.
[0018] A twelfth aspect of the present invention is a substrate processing method for supplying an etching solution to a substrate to perform etching, comprising the steps of holding the substrate in a horizontal position, the substrate being etched within a gap having a width of 20 nm or less, and rotating the substrate around an axis facing vertically; supplying the etching solution to the surface of the substrate; and repeatedly accelerating and decelerating the rotation of the substrate while the etching solution is present on the substrate, thereby generating a vortex within the gap during etching, the vortex centered on an axis perpendicular to the depth direction of the gap. [Effects of the Invention]
[0019] According to the present invention, it is possible to improve the efficiency of removing the etching target in a minute gap. [Brief explanation of the drawings]
[0020] [Figure 1] FIG. 1 is a front view showing a schematic configuration of a substrate processing apparatus. [Figure 2] FIG. 2 is a block diagram showing a part of the functional configuration of the substrate processing apparatus. [Figure 3] 10 is a flowchart showing an example of an operation of the substrate processing apparatus. [Figure 4] 10A and 10B are diagrams illustrating acceleration and deceleration of the rotation of the substrate. [Figure 5] FIG. 2 is a simplified diagram illustrating a structure to be etched. [Figure 6] FIG. 10 is a diagram showing a state in which a part of the TiN layer between the HK films has been removed. [Figure 7] FIG. 10 is a diagram showing the results of etching performed under various conditions. [Figure 8] FIG. 1 is a diagram showing a model for analyzing the flow of a liquid. [Figure 9] FIG. 10 is a diagram showing the results of fluid analysis for a plurality of models. [Figure 10A] FIG. 10 is a diagram for explaining a simulation result. [Figure 10B] FIG. 10 is a diagram for explaining a simulation result. [Figure 10C]FIG. 10 is a diagram for explaining a simulation result. [Figure 10D] FIG. 10 is a diagram for explaining a simulation result. DETAILED DESCRIPTION OF THE INVENTION
[0021] FIG. 1 is a front view showing a schematic configuration of a substrate processing apparatus 1 according to one embodiment of the present invention. FIG. 1 shows a portion of the substrate processing apparatus 1 in longitudinal cross section. The substrate processing apparatus 1 is a single-wafer processing apparatus that supplies an etching solution to a substrate 9 for etching. The substrate processing apparatus 1 includes a substrate holding unit 11, a substrate rotating unit 12, a cup unit 13, multiple supply nozzles 141, and a housing 15. The substrate holding unit 11, the substrate rotating unit 12, the cup unit 13, and the supply nozzles 141 are housed in the internal space of the housing 15. An airflow generating unit 151 is provided in the canopy of the housing 15 to supply gas into the internal space and generate a downward airflow (so-called downflow). An FFU (fan filter unit), for example, is used as the airflow generating unit 151. The substrate processing apparatus 1 further includes a control unit (not shown), which controls the substrate holding unit 11, the substrate rotating unit 12, the cup unit 13, the supply nozzles 141, etc.
[0022] The substrate holder 11 holds the substrate 9 in a horizontal position. The substrate holder 11 is a chuck that holds the center of the lower surface of the substrate 9 by suction. The chuck has many tiny openings on the upper surface and is a so-called vacuum chuck that holds the lower surface of the substrate 9 by sucking in gas through the openings.
[0023] The substrate rotation unit 12 is disposed below the substrate holding unit 11. The substrate rotation unit 12 rotates the substrate 9 together with the substrate holding unit 11 around a rotation axis J1 that faces the vertical direction. The substrate rotation unit 12 includes a shaft 121 and a motor 122. The shaft 121 is a substantially columnar or cylindrical member centered on the rotation axis J1. The shaft 121 extends in the vertical direction and is connected to the center of the underside of the substrate holding unit 11. The motor 122 is an electric rotary motor that rotates the shaft 121. Note that the substrate rotation unit 12 may be a motor having another structure (for example, a hollow motor, etc.).
[0024] The supply nozzles 141 supply a processing liquid to the surface of the substrate 9 held by the substrate holder 11 to perform liquid processing on the substrate 9. The processing liquid includes chemical liquids such as SPM (Sulfuric acid hydrogen peroxide mixture (aqueous mixture of sulfuric acid and hydrogen peroxide)), SC1 (aqueous mixture of ammonia and hydrogen peroxide), SC2 (aqueous mixture of hydrochloric acid and hydrogen peroxide), diluted hydrogen peroxide, and DIW (deionized water) as a rinse liquid. Some of the chemical liquids are used as etching liquids. FIG. 1 shows two supply nozzles 141 that eject processing liquids from above the substrate 9 toward the upper surface of the substrate 9, but other nozzles may also be provided. The ejection outlet of each supply nozzle 141 can be moved between a position above the substrate 9 and a position away from the substrate 9 by a nozzle movement mechanism (not shown).
[0025] The cup unit 13 has an annular cup centered on the rotation axis J1, and the cup receives liquid such as the processing liquid that splashes from the rotating substrate 9 toward the periphery. A drain port (not shown) is provided at the bottom of the cup unit 13 to discharge the processing liquid received in the cup to the outside of the housing 15. In reality, multiple cups are arranged concentrically, and each cup is movable up and down. Each cup receives a specific liquid that splashes from the substrate 9.
[0026] FIG. 2 is a block diagram showing a portion of the functional configuration of the substrate processing apparatus 1, including the substrate rotation unit 12, the control unit 16, and the processing liquid supply unit 14. In addition to the supply nozzle 141, the processing liquid supply unit 14 includes an etching liquid supply source 142, an IPA supply source 143, a mixer 144, and a deionized water supply source 145. The etching liquid supply source 142 stores an etching liquid. The term "etching liquid" refers to a liquid that has the property of dissolving and removing a specific substance (the etching target) on the substrate 9. However, the term is not limited to such a liquid and includes liquids used for removing a portion of the etching target on the substrate 9 or for removing particles on the substrate 9 by utilizing its ability to dissolve the specific substance. As described above, the concept of "removing the etching target with an etching liquid" encompasses various modes of removing the specific substance. The processing liquid supply unit 14 also includes supply sources for introducing various other chemical liquids to the supply nozzle 141, but these are not shown in the figure.
[0027] The IPA supply source 143 stores IPA (isopropyl alcohol). The etching liquid supply source 142 and the IPA supply source 143 are connected to a mixing section 144. When only the etching liquid is introduced from the etching liquid supply source 142 to the mixing section 144, the etching liquid is introduced to the supply nozzle 141, and the etching liquid is supplied onto the substrate 9. When the etching liquid is introduced from the etching liquid supply source 142 to the mixing section 144 and at the same time IPA is introduced from the IPA supply source 143 to the mixing section 144, the etching liquid and IPA are mixed in the mixing section 144, and the mixed liquid is introduced to the supply nozzle 141, and the mixed liquid is supplied onto the substrate 9.
[0028] IPA is used to reduce the surface tension of the etching solution, and hereinafter, a mixture of the etching solution and IPA, i.e., an etching solution with reduced surface tension, is referred to as a "mixed etching solution." The low-surface-tension liquid that reduces the surface tension of the etching solution may be a liquid other than IPA. For example, the surface tension of the etching solution may be reduced by mixing methanol. The proportion of the low-surface-tension liquid in the mixed etching solution is preferably 5 vol% or more and 30 vol% or less.
[0029] As will be described later, since the rotation of the substrate 9 is accelerated or decelerated while the etching liquid is being supplied to the substrate 9, it is preferable that the diameter of the outlet of the supply nozzle 141 that discharges the etching liquid be small to prevent liquid splashing. The diameter of the outlet of the supply nozzle 141 that discharges the etching liquid is preferably 5 mm or less, and more preferably 4 mm or less. There is no particular lower limit to the diameter of the outlet, but it is, for example, 1 mm or more.
[0030] The pure water supply source 145 is connected to a supply nozzle 141 separate from the supply nozzle 141 that ejects the etching liquid, and when pure water is introduced from the pure water supply source 145 to the supply nozzle 141, the pure water is supplied onto the substrate 9 from the supply nozzle 141.
[0031] The control unit 16 controls the rotation of the substrate 9 by the substrate rotation unit 12 and the supply of etching liquid, pure water, etc. from the processing liquid supply unit 14 to the substrate 9.
[0032] 3 is a flowchart showing an example of the operation of the substrate processing apparatus 1. When an external robot loads one substrate 9 into the housing 15 of the substrate processing apparatus 1, the substrate 9 is held by suction on the substrate holder 11 (step S11). The substrate rotation unit 12 starts rotating the substrate 9 (step S12), and when a predetermined rotation speed is reached, diluted hydrofluoric acid (DHF) guided from a DHF supply source (not shown) is supplied onto the upper surface of the substrate 9 through the supply nozzle 141 (step S13). Subsequently, pure water is guided from the pure water supply source 145 to the supply nozzle 141, and the pure water is supplied onto the substrate 9 (step S14).
[0033] Next, etching liquid from etching liquid supply source 142 is supplied to the upper surface of substrate 9 via supply nozzle 141 (step S15). Once the etching liquid has spread over the upper surface of substrate 9, the rotational speed of substrate 9 is increased and decreased, i.e., rotation is rapidly accelerated and decelerated repeatedly (step S16) in parallel with the supply of the etching liquid. The rotational acceleration is 3000 rpm / s or more, and accelerations of 3000 rpm / s or more and decelerations of 3000 rpm / s or more (-3000 rpm / s or less when expressing the direction of rotation) are repeated. Because such high accelerations cannot be achieved in conventional substrate processing apparatuses, substrate holder 11 of substrate processing apparatus 1 is a high-performance vacuum chuck.
[0034] The maximum acceleration value is not limited, but is, for example, 15,000 rpm / s, and an acceleration that can be achieved at a realistic cost is 12,500 rpm / s. The rotation speed of the substrate 9 during acceleration / deceleration is not particularly limited, but is, for example, 100 rpm or more and 3,000 rpm or less, and preferably 300 rpm or more and 1,500 rpm or less. Of course, the speed may be 0 rpm at times, and may include reverse rotation.
[0035] Next, when a predetermined time has elapsed since the start of supply of the etching liquid, the etching liquid from the etching liquid supply source 142 and the IPA from the IPA supply source 143 are introduced into the mixer 144 while continuing to accelerate and decelerate the rotation, and the mixed etching liquid is supplied onto the substrate 9 from the supply nozzle 141 (step S17). When a predetermined time has elapsed since the start of supply of the mixed etching liquid, the acceleration and deceleration of the rotation are stopped (step S18), and the substrate 9 rotates at a constant speed.
[0036] Next, pure water is introduced from the pure water supply source 145 to the supply nozzle 141, and the pure water is supplied onto the substrate 9 (step S19). After a predetermined time has elapsed, the supply of pure water onto the substrate 9 is stopped, and the substrate 9 is rotated at high speed to dry the substrate 9 (step S20). Thereafter, the rotation of the substrate 9 is stopped (step S21), and the substrate 9 is carried out of the housing 15 by a robot external to the substrate processing apparatus 1.
[0037] FIG. 4 illustrates the acceleration and deceleration of the rotation of the substrate 9 performed between steps S16 and S18. The solid polygonal line labeled 21 indicates the acceleration and deceleration of the rotation of the substrate 9 in the substrate processing apparatus 1, while the dashed polygonal line labeled 22 indicates the acceleration and deceleration possible in a conventional apparatus that grips the substrate with claws. Polygonal line 21 indicates repeated acceleration and deceleration at 9000 rpm / s between 300 rpm and 900 rpm. Polygonal line 22 indicates repeated acceleration and deceleration at 1000 rpm / s between 300 rpm and 600 rpm. The combination of acceleration and deceleration is preferably repeated once every 2 to 20 seconds, more preferably once every 4 to 10 seconds. The number of repetitions is determined appropriately depending on the desired etching depth and trench size.
[0038] FIG. 5 is a simplified diagram of a target structure 90 used to verify the effect of applying high acceleration during etching. The target structure 90 is a gate-all-around (GAA) structure included in a complementary metal oxide semiconductor (CMOS). The target structure 90 is a vertically arranged HfO2 high-k film (HK film) 92 formed around multiple silicon portions (hereinafter simply referred to as "Si portions") 91 corresponding to gates. Titanium nitride layers (hereinafter referred to as "TiN layers") 93 are present around the HK films 92 and in the gaps between the HK films 92. During the etching process, the etchant dissolves the TiN layers 93, gradually removing the TiN layers 93 between the HK films 92 from the outside over time. The TiN layers 93 are the target of etching. The "gaps" are the regions between opposing surfaces made of a material that is not etched by the etchant.
[0039] Note that silicon may be replaced with other semiconductors such as germanium, and the material of the high-k film may be other materials such as Al2O3 or La2O3. The etching target is not limited to TiN. The etching target is preferably TaN (tantalum nitride), LaO (lanthanum oxide), TiAlC, TiAl (titanium aluminum), W (tungsten), or TiNOC. Of course, the etching target may also be other materials.
[0040] FIG. 6 shows the state where a portion of the TiN layer 93 between the HK films 92 has been removed after a certain time has elapsed since the start of etching. The distance marked with a reference symbol 94 indicates the distance between the HK films 92 where the TiN layer 93 has been removed. Hereinafter, this distance 94 will be referred to as the "etching amount." Etching efficiency can be evaluated by performing etching under various conditions and obtaining the etching amount 94 after a certain time has elapsed since the start of etching. Reference symbol 95 indicates the position of the gap, and the range marked with a reference symbol 96 indicates the gap width, i.e., the size of the gap.
[0041] Figure 7 shows the etching amount when etching was performed under various conditions. The horizontal axis of Figure 7 represents time, and the vertical axis represents the etching amount 94 [nm]. The area marked with reference numeral 81 in Figure 7 shows the results when the distance (gap size) between HK films 92 was 2 nm and acceleration / deceleration was performed at 1000 rpm / s. The etching amount was 13 nm when the etching time was 8 minutes, and 17 nm when the etching time was 12 minutes.
[0042] The area marked with reference numeral 82 shows the results when the distance between the HK films 92 was 4 nm and the speed was accelerated and decelerated at 1000 rpm / s, resulting in an etching depth of 14 nm for an 8-minute etching time and 14 nm for an 12-minute etching time. The area marked with reference numeral 83 shows the results when the distance between the HK films 92 was 2 nm and the speed was accelerated and decelerated at 3000 rpm / s, resulting in an etching depth of 17 nm for an 8-minute etching time and 18 nm for an 12-minute etching time. The area marked with reference numeral 84 shows the results when the distance between the HK films 92 was 4 nm and the speed was accelerated and decelerated at 3000 rpm / s, resulting in an etching depth of 20 nm for an 8-minute etching time and 23 nm for an 12-minute etching time. Conditions other than those mentioned above were the same for each experiment.
[0043] From FIG. 7, it can be seen that the etching amount 94 is greater when accelerating and decelerating at 3000 rpm / s than when accelerating and decelerating at 1000 rpm / s.
[0044] An experiment was also conducted to compare acceleration and deceleration at 1000 rpm / s with acceleration and deceleration at 9000 rpm / s under conditions different from those shown in Figure 7. In this experiment, it was found that, compared to acceleration and deceleration at 1000 rpm / s, acceleration and deceleration at 9000 rpm / s increased the etching amount 94 by approximately 10% at the center of the substrate 9, approximately 16% at the middle part in the radial direction, and approximately 23% at the edge.
[0045] From the above, it can be said that it is preferable for substrate rotation unit 12 to repeatedly accelerate and decelerate the rotation of substrate 9 at a rotational acceleration of 3000 rpm / s or more when an etching solution is present on substrate 9. Furthermore, it is thought that the greater the acceleration, the greater the etching effect inside the minute gap, and it can be said that it is even more preferable for substrate rotation unit 12 to repeatedly accelerate and decelerate the rotation of substrate 9 at a rotational acceleration of 6000 rpm / s or more when an etching solution is present on substrate 9.
[0046] Figure 8 shows a model 30 for analyzing the flow of liquid in an extremely narrow recess (trench) when rotational acceleration is applied to a substrate. Model 30 has an upper portion 31 above the surface of the substrate and a lower portion 32 corresponding to the recess provided in the substrate. Upper portion 31 is a rectangular prism with a square base having sides of La and a thickness of Lt. Lower portion 32 is a rectangular prism with a square base having sides of Lb and a height, i.e., depth of the recess, of Ld. Lower portion 32 is connected to the center of the lower surface of upper portion 31. The upper portion is the calculation range on the substrate, and the fluid passes horizontally through upper portion 31. Because lower portion 32 is the calculation range within the recess, the fluid does not travel to or from the outside of lower portion 32 except at the upper end.
[0047] FIG. 9 shows the results of fluid analysis for multiple models 30, illustrating the relationship between the position (depth) on the central axis of the model and the flow velocity. For each model 30, the magnitudes of La and Lt are appropriately set because they do not affect the simulation. In FIG. 9, for the model corresponding to reference numeral 41, Lb = 4 nm and Ld = 10 nm, and a substrate with a radius of 100 mm was rotated at 300 rpm without acceleration. For the model corresponding to reference numeral 42, Lb = 4 nm and Ld = 10 nm, and acceleration was applied between 300 rpm and 600 rpm at an acceleration of 9000 rpm / s. The other conditions were the same as for reference numeral 41. For the model corresponding to reference numeral 43, Lb = 4 nm and Ld = 20 nm, and, like reference numeral 41, no acceleration was applied. For the model corresponding to reference numeral 44, Lb = 4 nm and Ld = 20 nm, and acceleration was applied under the same conditions as reference numeral 42.
[0048] In the model corresponding to reference numeral 45, Lb = 2 nm, Ld = 10 nm, and no acceleration was applied, as in the case of reference numeral 41. In the model corresponding to reference numeral 46, Lb = 2 nm, Ld = 10 nm, and acceleration was applied under the same conditions as in the case of reference numeral 42. In the model corresponding to reference numeral 47, Lb = 1 nm, Ld = 10 nm, and no acceleration was applied, as in the case of reference numeral 41. In the model corresponding to reference numeral 48, Lb = 1 nm, Ld = 10 nm, and acceleration was applied under the same conditions as in the case of reference numeral 42.
[0049] From the graphs indicated by the reference numerals 41 to 48, it can be seen that by applying a large acceleration, the fluid moves to the bottom of even a minute recess.
[0050] 10A to 10D are diagrams illustrating the results of the simulation. As shown by arrow 51 in FIG. 10A, while substrate 9 is rotating at a constant high speed, both the fluid and recess 52 move at high speed. When the rotation of substrate 9 slows down, as shown by arrow 53 in FIG. 10B, the movement speed of recess 52 decreases, but as shown by arrow 54, the fluid does not decrease as much as the speed of recess 52 due to inertia. Therefore, a vortex 55 is generated on the surface of substrate 9, i.e., above recess 52, and this flow propagates downward, creating a flow inside recess 52.
[0051] As shown by arrow 56 in FIG. 10C, while substrate 9 is rotating at a constant slow speed, both the fluid and recess 52 move at a slow speed. When the rotation of substrate 9 accelerates, as shown by arrow 57 in FIG. 10D, the movement speed of recess 52 increases, but as shown by arrow 58, the fluid does not increase as fast as the speed of recess 52 due to inertia. Therefore, vortices 59 are generated on the surface of substrate 9, i.e., above recess 52, and this flow propagates downward, causing a flow inside recess 52. Vortices 55 and 59 are vortices centered on an axis perpendicular to the depth direction of recess 52. In the simulation, vortices corresponding to the above-mentioned vortices 55 and 59 were confirmed within the upper end of lower portion 32 of model 30 (see FIG. 8).
[0052] The vortex is centered on an axis perpendicular to the depth direction of the gap. However, the term "vortex centered on an axis perpendicular to the depth direction of the gap" here refers to a vortex with a different component than a vortex centered on an axis parallel to the depth direction, and does not refer to a vortex generated around an axis exactly perpendicular to the depth direction of the gap. Simulation results showed that when a rotational acceleration sufficient for effective etching is applied, the flow velocity of a vortex (vortex component) centered on an axis parallel to the radial direction is greater than that of a vortex (more precisely, a vortex component) centered on an axis parallel to the circumferential direction.
[0053] As described above, even for minute recesses, accelerating and decelerating the rotation of the substrate 9 at an acceleration of 3000 rpm or more can induce fluid movement within the minute gap, improving the efficiency of removing the etching target within the minute gap. The term "gap" here is not limited to the space between two surfaces, but also includes recesses and through-holes. This effect is suitable for cases where the etching target of the substrate 9 is located within a gap of 20 nm or less in width, which could not be efficiently etched using conventional methods.
[0054] More preferably, the etching target is present in a gap having a width of 10 nm or less. Even more preferably, the etching target is present in a gap having a width of 4 nm or less, and even more preferably, the etching target is present in a gap having a width of 3 nm or less. Then, under the control of control unit 16, substrate rotation unit 12 repeatedly accelerates and decelerates the rotation of substrate 9 while the etching solution is present on substrate 9, thereby generating a vortex in the gap during etching about an axis perpendicular to the depth direction of the gap, thereby improving the efficiency of removing the etching target from the gap even in a very small gap.
[0055] The gap, inside which the etching target exists, typically extends in a direction perpendicular to the surface of the substrate 9. This allows the speed difference of the etching solution generated at the opening at the top end of the gap to propagate through the gap, improving the efficiency of etching within the gap.
[0056] Alternatively, the gap may extend from a plane perpendicular to the surface of the substrate 9 in a direction parallel to the surface of the substrate 9. The gap 95 between the HK films 92 in FIG. 6 is a gap extending from a plane 97 perpendicular to the surface of the substrate 9, indicated by a dashed line, in a direction parallel to the surface of the substrate 9. In this case, the etching target (TiN layer 93 in FIG. 6 ) is present both inside and outside the gap, and the etching solution flows as the rotation of the substrate 9 accelerates or decelerates, causing etching by the etching solution to proceed from outside the gap to inside the gap. Even if the left and right spaces of the target structure 90 in FIG. 6 are minute vertical gaps extending vertically, as described with reference to FIGS. 10A to 10D , the flow reaches the bottom of the minute vertical gap, and etching by the etching solution proceeds from outside the horizontal gap (gap 95) to inside the gap. Thus, gaps containing etching targets may exist in various forms on the substrate 9.
[0057] The acceleration and deceleration of the rotation of substrate 9 in steps S16 to S18 does not need to be performed constantly while the etching solution is being supplied onto substrate 9. For example, in the structure of Fig. 6, if the time when etching in gap 95 will start is known, acceleration and deceleration of the rotation of substrate 9 may start at that time. In other words, acceleration and deceleration of the rotation of substrate 9 are repeated under the control of control unit 16 at least while etching is being performed in the gap.
[0058] Furthermore, since the mixed etching liquid supplied to the substrate 9 in step S17 has reduced surface tension, it is preferably supplied to the substrate 9 in order to improve the etching rate (etching amount per unit time) when etching is performed in the gap. That is, it is preferable that IPA, which is a low surface tension liquid, is mixed into the etching liquid when etching is performed in the gap under the control of the control unit 16. Therefore, it is preferable that acceleration and deceleration of the rotation of the substrate 9 are repeated under the control of the control unit 16 while the mixed etching liquid is being supplied to the substrate 9.
[0059] The supply of the mixed etching solution to the substrate 9 is started when a predetermined time has elapsed since the start of the supply of the etching solution to the substrate 9. This timing may be detected by monitoring the concentration of the etching target contained in the etching solution discharged from the substrate 9, or may be determined by monitoring the pH (hydrogen ion exponent) of the etching solution discharged from the substrate 9. If the color of the etching solution changes depending on the content of the etching target, the color of the etching solution discharged from the substrate 9 may be monitored. If the etching target is a metal or a metal compound, the conductivity of the etching solution discharged from the substrate 9 may be monitored.
[0060] The results in Figure 9 indicate that flow occurs even when the gap size is 1 nm. Furthermore, since sufficient flow occurs even when the gap size is 1 nm and the depth is 10 nm, it is believed that flow will occur within the gap if the gap depth (depth) is 10 times or less than the gap width, and even if it is 15 times or less. It has been confirmed that a gap width of 4 nm cannot be sufficiently etched at an acceleration of approximately 1000 rpm / s. Therefore, the above condition of a gap depth of 15 times or less or 10 times or less than the gap width is particularly preferable when the gap width is 4 nm or less. While the minimum gap depth is not particularly limited, it is preferable to apply an acceleration of 3000 rpm / s or more to the rotation of substrate 9 when the gap depth is 1 time or more the gap width.
[0061] The substrate processing apparatus 1 and its operation may be modified in various ways.
[0062] The substrate 9 is not limited to a semiconductor substrate, but may be a glass substrate for a photomask, a glass substrate for a liquid crystal display, a glass substrate for a plasma display, a substrate for an FED (Field Emission Display), a substrate for an optical disk, a substrate for a magnetic disk, a substrate for a magneto-optical disk, or the like.
[0063] The etching solution is not limited to the above examples. Various substances may be used as the etching solution as long as they can dissolve the etching target. For example, hydrochloric acid, hydrogen peroxide, hydrofluoric acid, etc. can also be used as the etching solution.
[0064] The substrate holder 11 preferably has a vacuum chuck, but the type of the vacuum chuck is not particularly limited. Also, a holder other than a vacuum chuck, for example, a holder that firmly fixes the outer periphery of the substrate 9, may be used.
[0065] The substrate rotation unit 12 is preferably an electric motor. Various motor structures may be used as long as the substrate 9 is rotated around the central axis of the substrate 9, which is oriented in the vertical direction. For example, the shaft 121 may be solid or hollow. When a vacuum chuck is used, the shaft 121 is preferably hollow. An annular rotor may also be used.
[0066] As already explained, the objects controlled by the control unit 16 and the structure of the processing liquid supply unit 14 in Fig. 2 are only a partial illustration. Various processing liquids (chemical solutions, pure water, etc.) are supplied to the mixing unit 144 of the processing liquid supply unit 14. Furthermore, there may be multiple mixing units 144, and various types of supply nozzles 141 may be provided. The supply nozzle 141 may be fixed or mobile.
[0067] The acceleration and deceleration of the rotation of the substrate 9 is preferably performed while the etching target of the substrate 9 is in contact with the etching solution, but the acceleration and deceleration of the rotation of the substrate 9 may start before the etching target comes into contact with the etching solution.
[0068] The flow of operations of the substrate processing apparatus 1 in Figure 3 is merely an example. The operations in Figure 3 may be modified in various ways. For example, the step of supplying the mixed etching liquid to the substrate 9 (step S17) does not need to be performed. A diluted low-surface tension liquid, for example, diluted IPA, may be supplied to the substrate 9 before the supply of pure water (step S19). Various other operations may be added to Figure 3, or some operations may be omitted. The order of each step in Figure 3 may be changed within the range in which the substrate 9 can be processed.
[0069] The configurations in the above-described embodiment and each modification may be combined as appropriate as long as they are not mutually contradictory. [Explanation of symbols]
[0070] 1. Substrate processing equipment 9 Substrate 11 Substrate holder (vacuum chuck) 12 Substrate rotation unit 14 Processing liquid supply unit 16 Control Unit 55,59 Vortex 93 TiN layer 95 Gap 97 (perpendicular to the surface of the board) S11~S22 steps
Claims
1. A substrate processing apparatus that supplies an etching solution to a substrate to perform etching, a substrate holder that holds the substrate in a horizontal position; a substrate rotation unit that rotates the substrate together with the substrate holder around an axis that faces a vertical direction; a processing liquid supply unit that supplies an etching liquid to the surface of the substrate held by the substrate holder; a control unit that controls the rotation of the substrate by the substrate rotation unit and the supply of the etching liquid from the processing liquid supply unit; Equipped with The etching target of the substrate is present within a gap having a width of 20 nm or less, The substrate processing apparatus controls the control unit so that the substrate rotation unit repeatedly accelerates and decelerates the rotation of the substrate at a rotation acceleration of 3000 rpm / s or more while an etching solution is present on the substrate.
2. The substrate processing apparatus according to claim 1 , The substrate processing apparatus controls the control unit so that the substrate rotation unit repeatedly accelerates and decelerates the rotation of the substrate at a rotation acceleration of 6000 rpm / s or more while an etching solution is present on the substrate.
3. The substrate processing apparatus according to claim 1 , The substrate processing apparatus has a gap with a width of 10 nm or less, where the etching target is present.
4. The substrate processing apparatus according to claim 1 , The substrate processing apparatus, wherein the gap extends in a direction perpendicular to the surface of the substrate.
5. The substrate processing apparatus according to claim 1 , the gap extends from a plane perpendicular to a surface of the substrate to a direction parallel to the surface of the substrate; the etching target is present both outside and inside the gap, The substrate processing apparatus is configured such that etching with the etching liquid proceeds from outside the gap to inside the gap.
6. 6. The substrate processing apparatus according to claim 5, The substrate processing apparatus is configured such that the acceleration and deceleration of the rotation of the substrate are repeated under the control of the control unit at least while etching is being performed in the gap.
7. 6. The substrate processing apparatus according to claim 5, When etching is performed in the gap, a low surface tension liquid is mixed into the etching liquid under the control of the control unit.
8. The substrate processing apparatus according to claim 1 , The substrate processing apparatus is configured such that the etching target is TiN, TaN, LaO, TiAlC, TiAl, W, or TiNOC.
9. 9. The substrate processing apparatus according to claim 1, The substrate processing apparatus includes a substrate rotating unit having a vacuum chuck that holds the lower surface of the substrate.
10. A substrate processing apparatus that supplies an etching solution to a substrate to perform etching, a substrate holder that holds the substrate in a horizontal position; a substrate rotation unit that rotates the substrate together with the substrate holder around an axis that faces a vertical direction; a processing liquid supply unit that supplies an etching liquid to the surface of the substrate held by the substrate holder; a control unit that controls the rotation of the substrate by the substrate rotation unit and the supply of the etching liquid from the processing liquid supply unit; Equipped with The etching target of the substrate is present within a gap having a width of 20 nm or less, A substrate processing apparatus in which, under the control of the control unit, the substrate rotation unit repeatedly accelerates and decelerates the rotation of the substrate while an etching solution is present on the substrate, thereby generating a vortex within the gap during etching, centered on an axis perpendicular to the depth direction of the gap.
11. A substrate processing method for etching a substrate by supplying an etching solution to the substrate, comprising: a step of holding a substrate in a horizontal position, the substrate having an etching target present within a gap having a width of 20 nm or less, and rotating the substrate around an axis facing vertically; applying an etching solution to a surface of the substrate; repeating acceleration and deceleration of the rotation of the substrate at a rotation acceleration of 3000 rpm or more in a state where an etching solution is present on the substrate; A substrate processing method comprising:
12. A substrate processing method for etching a substrate by supplying an etching solution to the substrate, comprising: a step of holding a substrate in a horizontal position, the substrate having an etching target present within a gap having a width of 20 nm or less, and rotating the substrate around an axis facing vertically; applying an etching solution to a surface of the substrate; generating a vortex around an axis perpendicular to the depth direction of the gap during etching by repeatedly accelerating and decelerating the rotation of the substrate in a state where an etching solution is present on the substrate; A substrate processing method comprising:
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Method and equipment for treatment of to-be-treated body
JP2003272988A