Pattern formation method and semiconductor manufacturing apparatus

Abstract

This method improves the shape and roughness of patterns formed by etching using an etching mask formed with metal oxide resist. [Solution] The pattern formation method according to this embodiment involves applying a water-containing metal oxide resist onto the workpiece layer, heating it to form a MOR film, exposing the MOR film, heating the MOR film, developing the MOR film to form a resist pattern, and using the resist pattern as a mask to etch the workpiece layer to form a pattern.

Description

Technical Field

[0001] This embodiment relates to a pattern formation method and a semiconductor manufacturing apparatus.

Background Art

[0002] As a next-generation resist that maximizes the performance of next-generation EUV lithography (Extreme ultraviolet lithography) and contributes to further miniaturization and cost reduction, metal oxide resist (MOR: Metal Oxide Resist) has attracted attention. A metal oxide resist is a photoresist containing metal oxide nanoparticles (metal oxide nanoparticles) such as tin (Sn) that have a high absorption efficiency of EUV light. Metal oxide resists have the advantages of high sensitivity and high uniformity of the minimum line width (CD: Critical Dimension) compared to currently mainstream chemically amplified resists (CAR: Chemical Amplified Resist).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] On the other hand, in the case of metal oxide resists, the stability of the reaction mechanism is low with respect to moisture in the resist. Therefore, there is a risk of an increase in pattern defects due to the generation of resist residues (scum) in the unexposed areas.

[0005] The problem that this invention aims to solve is to improve the shape and roughness of patterns formed by etching using an etching mask formed with a metal oxide resist. However, the invention is not limited to this problem, and any problem corresponding to the effects obtained by the configuration of the embodiments described later may also be considered the problem of this invention. [Means for solving the problem]

[0006] According to the pattern formation method of this embodiment, a metal oxide resist containing water is applied to the workpiece layer and heated to form a MOR film. The MOR film is exposed, The MOR film is heated, The aforementioned MOR film is developed to form a resist pattern. The resist pattern is used as a mask to etch the workpiece layer and form a pattern.

[0007] Semiconductor manufacturing apparatus according to this embodiment, A spin coating section having a rotating platform for rotating a semiconductor substrate on which a layer to be processed has been formed, A resist supply unit that supplies a water-containing metal oxide resist onto the workpiece layer, The system includes a heating unit for heating the semiconductor substrate on which the water-containing metal oxide resist is coated. The resist supply unit is A nozzle for dispensing the aforementioned water-containing metal oxide resist, A MOR supply line through which metal oxide resist flows is connected to the nozzle, A water addition line connected to the nozzle or the MOR supply line through which water flows, It holds. [Brief explanation of the drawing]

[0008] [Figure 1] This is a flowchart illustrating the pattern formation method according to the embodiment. [Figure 2A]This is a schematic cross-sectional view illustrating the pattern formation method according to the embodiment. [Figure 2B] This is a schematic cross-sectional view illustrating the pattern formation method according to the embodiment, following Figure 2A. [Figure 2C] Figure 2B is a schematic cross-sectional view illustrating the pattern formation method according to the embodiment. [Figure 2D] Figure 2C is a schematic cross-sectional view illustrating the pattern formation method according to the embodiment. [Figure 2E] Figure 2D is a schematic cross-sectional view illustrating the pattern formation method according to the embodiment. [Figure 2F] Figure 2E is a schematic cross-sectional view illustrating the pattern formation method according to the embodiment. [Figure 3A] This is a schematic cross-sectional diagram illustrating the pattern formation method related to the comparative example, and corresponds to Figure 2B. [Figure 3B] This is a schematic cross-sectional diagram illustrating the pattern formation method related to the comparative example, following Figure 3A. [Figure 3C] Figure 3B is a schematic cross-sectional diagram illustrating the pattern formation method related to the comparative example. [Figure 3D] Figure 3C is a schematic cross-sectional diagram illustrating the pattern formation method related to the comparative example. [Figure 4] This is a plan view showing a schematic configuration of a semiconductor manufacturing apparatus according to an embodiment. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the drawings. These embodiments are not limiting to the present invention. The drawings are schematic or conceptual. The same elements are denoted by the same reference numerals in the specification and the drawings.

[0010] <Pattern Formation Method> Referring to the flowchart of FIG. 1 and FIGS. 2A to 2F, a pattern formation method according to an embodiment will be described. The pattern formation method according to this embodiment is applicable to the manufacture of semiconductor devices such as memory devices and logic devices, for example.

[0011] Step S1: Form a MOR film 20 with a metal oxide resist containing moisture w. In this embodiment, the moisture w is pure or ultrapure water.

[0012] Specifically, as shown in FIG. 2A, a metal oxide resist (MOR) is applied onto the processed layer 10 formed on the semiconductor substrate S by spin coating or the like, and heated by a hot plate or the like to form the MOR film 20. As shown in FIG. 2A, the MOR film 20 contains moisture w. The metal oxide resist to be applied contains, for example, 0.001 wt% to 20 wt% of moisture, preferably 1 wt% to 10 wt% of moisture, and more preferably 3 wt% to 7 wt% of moisture.

[0013] The application of the metal oxide resist is performed by dropping the metal oxide resist from a nozzle or the like onto the processed layer 10 and rotating the semiconductor substrate S at high speed. The heating (pre-baking) of the applied metal oxide resist is performed at a temperature and for a time such that the moisture in the metal oxide resist does not completely evaporate (for example, about 200°C to 250°C, about 30 seconds to 90 seconds). Thereby, at least a part of the solvent of the metal oxide resist evaporates and the film is stabilized.

[0014] Note that the metal atom of the metal oxide nanoparticles (not shown) contained in the metal oxide resist is Sn (tin) in this embodiment, but may be other metal atoms such as Zr (zirconium), Hf (hafnium), Ti (titanium), Zn (zinc), and Al (aluminum).

[0015] The semiconductor substrate S is, for example, a silicon wafer, but it may also be a semiconductor wafer made of other semiconductor materials (such as silicon carbide or compound semiconductors). Furthermore, the semiconductor substrate S is not limited to a semiconductor wafer; it may also be an epitaxial layer, or a semiconductor wafer with an epitaxial layer formed thereon.

[0016] Furthermore, the type of workpiece layer 10 is not particularly limited and may be a semiconductor layer (for example, an n-type or p-type silicon layer), a conductive layer (for example, a polysilicon layer, a metal layer), or an insulating layer (for example, an SiO2 film, a Si3N4 film, or an SiOC film).

[0017] Step S2: The MOR film 20 formed in Step S2 is exposed. Specifically, as shown in Figure 2B, the MOR film 20 is exposed using extreme ultraviolet lithography (EUV lithography). In the exposed portion of the MOR film 20, metal atoms detach from the organic ligands, generating metal atom radicals (M·).

[0018] [ka] Here, M is a metal atom and R is an organic ligand.

[0019] Some of the metal atom radicals generated in this way react with water w(H2O) in the MOR film 20 to produce metal hydroxyl groups (M-OH).

[0020] [ka]

[0021] In this embodiment, since the MOR film 20 was formed using a metal oxide resist containing water, the water concentration of the MOR film 20 is substantially uniform in the film thickness direction before the next step S3 is performed.

[0022] Step S3: The MOR film 20 exposed in Step S2 is heated. This step is a post-bake (PEB) process. Specifically, as shown in Figure 2C, the semiconductor substrate S is placed on a hot plate and heated. The heating conditions are, for example, 90°C to 120°C for 30 to 90 seconds.

[0023] When the MOR film 20 is heated, a condensation reaction (shown below) occurs in the exposed region, forming an insoluble substance (MOM).

[0024] [ka]

[0025] Step S4: The MOR film 20 heated in step S3 is developed to form a resist pattern RP. Specifically, as shown in Figure 2D, the portion of the MOR film 20 exposed in step S2 remains, and the resist pattern RP is formed.

[0026] Step S5: The workpiece layer 10 is etched using the resist pattern RP formed in step S4 as a mask to form pattern P. That is, as shown in Figure 2E, the workpiece layer 10 is etched using the resist pattern RP as an etching mask, and then the resist pattern RP is removed. This forms the desired pattern P shown in Figure 2F.

[0027] As described above, according to the pattern formation method of this embodiment, a water-containing MOR film 20 is formed on the workpiece layer 10, the MOR film 20 is exposed, heated, and developed to form a resist pattern RP, and the workpiece layer 10 is etched using the resist pattern RP as a mask to form a pattern P. This makes it possible to improve the shape and roughness of the pattern P.

[0028] The above effects will be explained in more detail through the description of the comparative example.

[0029] Figure 3A is a schematic cross-sectional view of the exposure process of the MOR film 200 according to the comparative example. Since the MOR film 200 does not contain water, the reaction of chemical formula 2 described above does not occur. Before the post-bake process (for example, during the PED process described later), as shown in Figure 3B, water w in the air is absorbed by the MOR film 200, generating M-OH. However, the water absorbed from the air into the MOR film 200 is not uniform, and the water content density is high near the top of the MOR film 200. Therefore, M-OH is abundant in the upper part of the MOR film 200. On the other hand, the density of M-OH is low in the lower part of the MOR film 200, so the reaction of chemical formula 3 is less likely to occur. Therefore, in the post-bake process shown in Figure 3C, insoluble MOM is formed mainly in the upper part of the MOR film 200.

[0030] Therefore, when the MOR film 200 is developed after the post-bake process, as shown in Figure 3D, the upper part of the exposed area of ​​the MOR film 200 remains, but the remaining area decreases towards the bottom, and the cross-section of the resist pattern RP becomes inversely tapered. As a result, the pattern formed by etching the workpiece layer 10 using the resist pattern RP1 as a mask deteriorates in shape and roughness.

[0031] In contrast, in this embodiment, since the metal oxide resist supplied onto the workpiece layer 10 is pre-moistened with water, after the metal oxide resist is supplied onto the workpiece layer 10, moisture from the air is absorbed mainly from the upper part of the metal oxide resist, suppressing a large change in moisture concentration in the film thickness direction. Thus, according to this embodiment, by applying and heating a moisture-containing metal oxide resist to form the MOR film 20, the moisture concentration of the MOR film 20 becomes substantially uniform in the film thickness direction before the post-bake process. Therefore, in the post-bake process, the reaction of chemical formula 3 occurs substantially uniformly in the film thickness direction of the MOR film 200, generating insoluble MOM. Consequently, the cross-section of the resist pattern RP does not become inversely tapered as shown in Figure 2D, and as a result, a pattern P with the desired shape and good roughness performance can be formed.

[0032] Furthermore, step S3 (heating of the MOR film 20) may be performed after a predetermined time (for example, several minutes) has elapsed since the exposure of the MOR film 20 in step S2. In other words, a post-exposure delay (PED) step may be included between the exposure step and the pre-baking step.

[0033] Furthermore, when performing the PED process, in step S1, the moisture content of the metal oxide resist containing moisture w may be gradually reduced while supplying it onto the workpiece layer 10. In this way, the moisture content increases at the bottom of the resist film coated on the workpiece layer 10 (the side closer to the semiconductor substrate S), and decreases towards the top of the resist film. As a result of moisture from the air being absorbed from the top of the MOR film 20 during the PED process, the uniformity of the moisture concentration in the film thickness direction of the MOR film 20 can be improved before the post-bake process.

[0034] Furthermore, when performing the PED process, in step S1, while supplying a metal oxide resist containing water w onto the workpiece layer 10, the rotation speed (rpm) of the semiconductor substrate S on which the workpiece layer 10 is formed may be gradually increased. Due to the difference in viscosity between the metal oxide resist and water, they are more likely to be scattered from the rapidly rotating semiconductor substrate S. By doing so, the amount of water increases at the bottom of the resist film applied on the workpiece layer 10 (closer to the semiconductor substrate S), and decreases towards the top of the resist film. As a result of absorbing moisture from the air from the top of the MOR film 20 during the PED process, the uniformity of the moisture concentration in the film thickness direction of the MOR film 20 can be increased before the post-bake process.

[0035] <Semiconductor Manufacturing Equipment> Referring to Figure 4, a semiconductor manufacturing apparatus 100 according to an embodiment will be described. The semiconductor manufacturing apparatus 100 is configured to receive a semiconductor substrate S (semiconductor wafer) from the outside, apply a water-containing metal oxide resist onto the workpiece layer 10 of the semiconductor substrate S, and heat to form a MOR film 20.

[0036] The semiconductor manufacturing apparatus 100 includes a resist supply unit 110, a spin coating unit 120, a heating unit 130, and transport units 141, 142, and 143. Although not shown in the figures, the semiconductor manufacturing apparatus 100 may also include a semiconductor substrate S pickup mechanism and a mechanism for aligning the semiconductor substrate S.

[0037] The resist supply unit 110 is configured to supply a water-containing metal oxide resist onto the workpiece layer 10 formed on the semiconductor substrate S. In this embodiment, the resist supply unit 110 drops the metal oxide resist onto the semiconductor substrate S fixed to the rotating platform of the spin coat unit 120.

[0038] The resist supply unit 110 includes a nozzle 111 for dispensing a metal oxide resist containing water, a MOR supply line 112 connected to the nozzle 111 through which the metal oxide resist flows, and a water addition line 113 through which water flows. The metal oxide resist flowing through the MOR supply line 112 does not contain water. However, it is not necessarily completely water-free and may contain a very small amount of water (for example, less than 0.0001 wt%).

[0039] The water addition line 113 may be connected to the MOR supply line 112 as shown in Figure 4, or it may be connected to the nozzle 111. In the latter case, the metal oxide resist and water are mixed inside the nozzle 111. With this resist supply unit 110, the mixture of water and metal oxide resist is discharged from the nozzle 111 and applied onto the workpiece layer 10.

[0040] As described above, in the resist supply unit 110, the water addition line 113 is connected to the nozzle 111 or the MOR supply line 112, so that the metal oxide resist and water are mixed just before being discharged from the nozzle 111 and supplied onto the workpiece layer 10. This makes it possible to control the water content of the metal oxide resist to a desired concentration with a simple configuration. By mixing a predetermined concentration of water with the metal oxide resist discharged from the nozzle 111 in this way, even if moisture from the air tries to enter the metal oxide resist on the workpiece layer 10, the water concentration in the metal oxide resist is suppressed from changing beyond a predetermined concentration due to so-called vapor-liquid equilibrium, and the water concentration in the metal oxide resist is maintained.

[0041] Furthermore, in order to control the amount of water contained in the metal oxide resist discharged from the nozzle 111, a valve (not shown), such as a needle valve or a simple proportional valve, may be installed before the point where the water addition line 113 merges with the MOR supply line 112. Alternatively, a mass flow meter may be installed in the MOR supply line 112 and / or the water addition line 113 to measure the flow rate of the MOR supply line 112 and / or the water addition line 113 and to control the valve accordingly.

[0042] Additionally, the moisture content of the metal oxide resist in the nozzle 111 may be monitored, and if the moisture content deviates from the target value, the flow rate of the MOR supply line 112 and / or water addition line 113 may be adjusted. Refractive index sensors, viscosity sensors, near-infrared spectrometers, etc., can be used to measure the moisture content.

[0043] Furthermore, the nozzle 111 may have a valve (e.g., a solenoid valve, a pinch valve) at its tip to control the amount of water-containing metal oxide resist discharged (supplied).

[0044] The spin coating unit 120 has a rotating platform for rotating the semiconductor substrate S. The spin coating unit 120 rotates the semiconductor substrate S, which is fixed to the rotating platform, at high speed, via the transport unit 141. While the semiconductor substrate S is rotating at high speed, a metal oxide resist containing water is supplied (dropped) from the resist supply unit 110, thereby forming a resist film on the workpiece layer 10.

[0045] Furthermore, while supplying (discharging) a water-containing metal oxide resist onto the workpiece layer 10, the resist supply unit 110 may gradually reduce the water content of the metal oxide resist. For example, the opening of a valve provided in the water addition line 113 may be gradually reduced. By discharging a metal oxide resist containing a relatively large amount of water in the initial stages of discharge and gradually reducing the water content, the amount of water increases at the bottom of the resist film coated on the workpiece layer 10 (the side closer to the semiconductor substrate S), and decreases towards the top of the resist film. As a result, during the PED process, moisture from the air is absorbed from the top of the MOR film 20, which improves the uniformity of the water concentration in the film thickness direction of the MOR film 20 before the post-bake process.

[0046] Furthermore, while supplying (discharging) a water-containing metal oxide resist onto the workpiece layer 10, the resist supply unit 110 may gradually increase the rotation speed (rpm) of the semiconductor substrate S on which the workpiece layer 10 is formed. Since water is more easily scattered than metal oxide resist on a rapidly rotating semiconductor substrate S, doing so increases the amount of water in the lower part of the resist film applied on the workpiece layer 10 (the side closer to the semiconductor substrate S), and decreases as you move towards the top of the resist film. As a result of absorbing moisture from the air from the top of the MOR film 20 during the PED process, the uniformity of the water concentration in the film thickness direction of the MOR film 20 before the post-bake process can be improved.

[0047] As described above, the moisture profile at the resist ejection stage may be set in anticipation of moisture absorption during the PED process, so that the moisture content of the metal oxide resist is as uniform as possible in the film thickness direction before the post-bake process. This is effective in improving the uniformity of the moisture concentration in the film thickness direction of the MOR film 20 before the post-bake process.

[0048] The heating unit 130 is transported by the transport unit 142 and is configured to heat the semiconductor substrate S on which a moisture-containing metal oxide resist is coated onto the workpiece layer 10. In this embodiment, the heating unit 130 has a hot plate, and the semiconductor substrate S is placed on the hot plate. The heating means for the hot plate is, for example, a ceramic heater, a resistance wire embedded heater, or a mica heater. The heating conditions are, for example, 200°C to 250°C and 30 to 90 seconds. As shown in Figure 4, multiple semiconductor substrates S may be placed on the hot plate and heated together at once.

[0049] The transport units 141, 142, and 143 transport the semiconductor substrate S. Transport unit 141 transports the semiconductor substrate S received from outside the semiconductor manufacturing apparatus 100 along the transport direction T1 to the spin coating unit 120. Transport unit 142 transports the semiconductor substrate S from the spin coating unit 120 to the heating unit 130 along the transport direction T2. ​​Transport unit 143 transports the semiconductor substrate S from the heating unit 130 to the outside of the semiconductor manufacturing apparatus 100 (for example, an exposure apparatus) along the transport direction T3. Note that transport units 141, 142, and 143 are not limited to one transport line, but may have multiple transport lines.

[0050] According to the semiconductor manufacturing apparatus 100 of this embodiment, a semiconductor substrate S received from outside the apparatus is transported to the spin coating section 120 by a transport section 141, and a resist supply section 110 applies a water-containing metal oxide resist onto the workpiece layer 10 of the semiconductor substrate S fixed to the rotating table of the spin coating section 120. Then, a heating section 130 heats the applied metal oxide resist to evaporate the solvent and form a MOR film 20.

[0051] The semiconductor substrate S, after being removed from the semiconductor manufacturing apparatus 100, is then transported to an exposure apparatus and developing apparatus, such as an EUV lithography apparatus (not shown), where the MOR film 20 is exposed and developed to form a resist pattern RP. Subsequently, in an etching apparatus (not shown), the workpiece layer 10 is etched using the resist pattern RP as a mask, thereby forming a resist pattern RP with a desired shape and good roughness performance. By etching the workpiece layer 10 using this resist pattern RP as an etching mask, a good pattern P can be formed.

[0052] In this embodiment, the semiconductor manufacturing apparatus 100 was configured as a so-called coater apparatus, but the configuration of the semiconductor manufacturing apparatus 100 is not limited to the above. For example, the semiconductor manufacturing apparatus 100 may include an exposure unit and a developing unit that receive the semiconductor substrate S heated in the heating unit 130 and pattern the MOR film 20, or it may further include an etching unit that etches the workpiece layer 10 using the patterned MOR film 20 as a mask.

[0053] Based on the above description, those skilled in the art may conceive of additional effects and various modifications of the present invention, but the embodiments of the present invention are not limited to the individual embodiments described above. Components from different embodiments may be combined as appropriate. Various additions, modifications, and partial deletions are possible without departing from the conceptual idea and spirit of the present invention derived from the claims and their equivalents. [Explanation of Symbols]

[0054] 10 Processed layer 20,200 MOR membrane 100 Semiconductor manufacturing equipment 110 Resist supply unit 111 Nozzles 112 MOR supply line 113 Water addition line 120 Spin Court Section 130 Heating section 141, 142, 143 Conveyor section RP,RP1 Resist Pattern P pattern S Semiconductor substrate T1, T2, T3 Conveying direction w Moisture

Claims

1. A metal oxide resist containing water is applied to the workpiece layer and heated to form a MOR film. The MOR film is exposed to light, The MOR film is heated, The MOR film is developed to form a resist pattern. A pattern forming method comprising etching the workpiece layer using the resist pattern as a mask to form a pattern.

2. The pattern forming method according to claim 1, wherein the water is pure or ultrapure water.

3. The pattern forming method according to claim 1, wherein the metal oxide resist contains 3 wt% to 7 wt% of water.

4. The pattern forming method according to claim 1, wherein the MOR film is heated after a predetermined time has elapsed since exposure of the MOR film.

5. The pattern forming method according to claim 4, wherein the moisture content of the metal oxide resist is gradually reduced while the moisture-containing metal oxide resist is supplied onto the layer to be processed.

6. The pattern forming method according to claim 4, wherein the rotation speed of the semiconductor wafer on which the workpiece layer is formed is gradually increased while the water-containing metal oxide resist is supplied onto the workpiece layer.

7. The pattern forming method according to claim 1, wherein the moisture concentration of the MOR film is substantially uniform in the film thickness direction before the MOR film is heated.

8. A spin coating section having a rotating platform for rotating a semiconductor substrate on which a layer to be processed has been formed, A resist supply unit that supplies a water-containing metal oxide resist onto the workpiece layer, The system includes a heating unit for heating the semiconductor substrate on which the water-containing metal oxide resist is coated. The resist supply unit is A nozzle for dispensing the aforementioned water-containing metal oxide resist, A MOR supply line through which metal oxide resist flows is connected to the nozzle, A water addition line through which water flows, connected to the nozzle or the MOR supply line, A semiconductor manufacturing device having the following features.

9. The semiconductor manufacturing apparatus according to claim 8, wherein the resist supply unit gradually reduces the moisture content of the metal oxide resist while supplying the moisture-containing metal oxide resist onto the layer to be processed.

10. The semiconductor manufacturing apparatus according to claim 8, wherein the resist supply unit gradually increases the rotation speed of the semiconductor wafer on which the workpiece layer is formed while supplying the water-containing metal oxide resist onto the workpiece layer.

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