Etching method and plasma processing system

Abstract

The present invention relates to an etching method and a plasma processing system. In an etching process of a processing object having an etching target layer and a mask layer formed with a pattern in advance formed on a surface, the surface morphology of the processing object is improved, and the consumption of the mask layer in the etching process is suppressed. An etching method for etching a processing object having an etching target layer and a mask layer formed with a pattern in advance formed on a layer above the etching target layer, the etching method comprising: a step (a) of etching the etching target layer with the mask layer as a mask; a step (b) of covering the surface of the processing object with a deposit; and a step (c) of etching the surface of the processing object covered with the deposit to planarize the surface.

Description

Technical Field

[0001] This disclosure relates to etching methods and plasma processing systems. Background Technology

[0002] Patent Document 1 discloses a method in which plasma etching is performed on a workpiece having a silicon layer and a pre-formed patterned resist film, using plasma generated from a specific combination of processing gases, with the resist film as a mask.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2007-258426 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] The technology involved in this disclosure is as follows: in the etching process of a processing object having an etchable object layer and a mask layer pre-patterned on its surface, the surface morphology of the processing object is improved and the consumption of the mask layer in the etching process is suppressed.

[0008] Solution for solving the problem

[0009] One aspect of this disclosure is an etching method for etching a workpiece having an etchable object layer formed on its surface and a mask layer formed on top of the etchable object layer and pre-patterned. The etching method includes the following steps: step (a) etching the etchable object layer using the aforementioned mask layer as a mask; step (b) covering the surface of the workpiece with a deposit; and step (c) etching the surface of the workpiece covered with the deposit to planarize the surface.

[0010] The effects of the invention

[0011] According to this disclosure, in the etching process of a processed object having an etchable object layer and a mask layer pre-patterned on its surface, the surface morphology of the processed object can be improved and the consumption of the mask layer in the etching process can be suppressed. Attached Figure Description

[0012] Figure 1 An explanatory diagram illustrating the morphological deterioration of the substrate surface.

[0013] Figure 2 A longitudinal cross-sectional view illustrating an example of the configuration of a plasma processing system.

[0014] Figure 3 This is an explanatory diagram showing the appearance of the etched object layer and the mask layer before and after the etching process involved in this embodiment.

[0015] Figure 4 An explanatory diagram illustrating the appearance of the sediment capping layer process according to this embodiment.

[0016] Figure 5 An explanatory diagram illustrating the appearance of the trimming process involved in this embodiment.

[0017] Figure 6 An explanatory diagram illustrating the results of embodiments of the technology involved in this disclosure.

[0018] Explanation of reference numerals in the attached figures

[0019] D Sediment(デポ)

[0020] DC sediment cover

[0021] Ox oxide film

[0022] R Anti-corrosion film

[0023] SiN SiN film

[0024] STN STN membrane

[0025] W substrate Detailed Implementation

[0026] In the manufacturing process of semiconductor devices, an etching process is performed on the etching target layer (e.g., a silicon-containing film) that is stacked and formed on the surface of a semiconductor substrate (hereinafter referred to as "substrate"), using a pre-patterned mask layer (e.g., a resist film) as a mask. This etching process is typically performed in a plasma processing apparatus.

[0027] Patent Document 1 discloses a method in which a sufficient relative mask selectivity and etching rate are ensured within the processing chamber of a plasma processing apparatus, and a resist film is used as a mask to etch a silicon film in a stacked layer. Specifically, etching is performed using plasma generated from a specific combination of processing gases, thereby enabling the processing of a stacked body containing the etched target layer within a single apparatus, achieving a reduction in apparatus size and a significant reduction in the number of steps and processing time.

[0028] However, in recent years, with the miniaturization of the patterns formed on the substrate surface of the mask layer, the pitch of the pattern has become narrower, raising concerns about the degradation of the substrate surface morphology, i.e. the deterioration of the substrate surface flatness, caused by the fluctuation of the CD (Critical Dimension: linewidth of the pattern) of the mask layer.

[0029] Specifically, for example Figure 1 As shown in (a), CD ripples are generated in the bars forming the mask layer, thus as... Figure 1 As shown in (b), the deposition height of the deposit D relative to the bar fluctuates. Furthermore, when etching the target layer is performed with such varying deposition heights of the deposit D, as... Figure 1 As shown in (c), the mask layer in the etching process produces a height difference H, which results in the deterioration of the surface morphology.

[0030] In the past, various methods have been proposed to improve the surface morphology, such as increasing the substrate temperature, reducing the processing pressure, and so on. However, these conventional methods involve a trade-off between morphological improvement and deterioration of the etch selectivity of the mask layer, meaning that the consumption of the mask layer during the etching process can no longer be suppressed.

[0031] The technology disclosed herein is made in view of the above circumstances, improving the surface morphology of a workpiece having an etchable object layer and a pre-patterned mask layer formed on its surface, and suppressing the consumption of the mask layer during the etching process. Hereinafter, a plasma processing system according to one embodiment and a plasma processing method including the etching method according to this embodiment will be described with reference to the accompanying drawings. It should be noted that in this specification and the accompanying drawings, elements having substantially the same functional configuration are labeled with the same reference numerals, thereby omitting repeated descriptions.

[0032] <Plasma Processing System>

[0033] First, a plasma processing system according to one embodiment will be described. Figure 2 This is a longitudinal cross-sectional view showing the general configuration of the plasma processing system 1. The plasma processing system 1 has a capacitively coupled plasma processing device. In the plasma processing system 1, a substrate W, which is the object to be processed, is subjected to plasma processing. In this embodiment, the plasma processing includes, for example, etching and ashing.

[0034] In one embodiment, the plasma processing system 1 includes a plasma processing apparatus 1a and a control unit 1b. The plasma processing apparatus 1a includes a plasma processing chamber 10, a gas supply unit 20, an RF (Radio Frequency) power supply unit 30, and an exhaust system 40. Additionally, the plasma processing apparatus 1a includes a support unit 11 and an upper electrode spray head 12. The support unit 11 is disposed in the lower region of the plasma processing space 10s within the plasma processing chamber 10. The upper electrode spray head 12 is disposed above the support unit 11 and functions as part of the ceiling of the plasma processing chamber 10.

[0035] The support portion 11 is configured to support the substrate W in the plasma processing space 10s. In one embodiment, the support portion 11 includes a lower electrode 111, an electrostatic chuck 112, and a side ring 113. The electrostatic chuck 112 is disposed on the lower electrode 111 and is configured to support the substrate W on its upper surface. The side ring 113 is configured to surround the substrate W on the upper surface of the peripheral portion of the lower electrode 111. Additionally, though not shown in the figures, in one embodiment, the support portion 11 may include a temperature regulating assembly configured to target the temperature of at least one of the electrostatic chuck 112 and the substrate W. The temperature regulating assembly may include a heater, a flow path, or a combination thereof. A temperature regulating fluid such as a refrigerant or a heat-conducting gas flows in the flow path.

[0036] The upper electrode spray head 12 is configured to supply one or more types of processing gases from the gas supply unit 20 to the plasma processing space 10s. In one embodiment, the upper electrode spray head 12 has a gas inlet 12a, a gas diffusion chamber 12b, and a plurality of gas outlets 12c. The gas inlet 12a is in fluid communication with the gas supply unit 20 and the gas diffusion chamber 12b. The plurality of gas outlets 12c are in fluid communication with the gas diffusion chamber 12b and the plasma processing space 10s. In one embodiment, the upper electrode spray head 12 is configured to supply one or more types of processing gases from the gas inlet 12a to the plasma processing space 10s via the gas diffusion chamber 12b and the plurality of gas outlets 12c.

[0037] The gas supply unit 20 may include one or more gas sources 21 and one or more flow controllers 22. In one embodiment, the gas supply unit 20 is configured to supply one or more types of process gases from their respective gas sources 21 to the gas inlet 12a via their respective flow controllers 22. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Furthermore, the gas supply unit 20 may include one or more flow modulation devices that modulate or pulse the flow rate of one or more types of process gases.

[0038] The RF power supply unit 30 is configured to supply RF power, such as one or more RF signals, to one or more electrodes, such as the lower electrode 111, the upper electrode spray head 12, or both the lower electrode 111 and the upper electrode spray head 12. This allows plasma to be generated by one or more processing gases supplied to the plasma processing space 10s. Therefore, the RF power supply unit 30 can function as at least part of a plasma generation unit configured to generate plasma from one or more processing gases in the plasma processing chamber 10. In one embodiment, the RF power supply unit 30 includes two RF generation units 31a and 31b and two matching circuits 32a and 32b. In one embodiment, the RF power supply unit 30 is configured to supply a first RF signal from the first RF generation unit 31a to the lower electrode 111 via the first matching circuit 32a. For example, the first RF signal may have a frequency in the range of 27MHz to 100MHz.

[0039] In another embodiment, the RF power supply unit 30 is configured to supply the second RF signal from the second RF generation unit 31b to the lower electrode 111 via the second matching circuit 32b. For example, the second RF signal may have a frequency in the range of 400 kHz to 13.56 MHz. A DC (Direct Current) pulse generation unit can be used instead of the second RF generation unit 31b.

[0040] Furthermore, while figures are omitted, other embodiments are considered in this disclosure. For example, in an alternative embodiment, the RF power supply unit 30 is configured to supply a first RF signal from the RF generation unit to the lower electrode 111, a second RF signal from other RF generation units to the lower electrode 111, and a third RF signal from further other RF generation units to the lower electrode 111. Additionally, in other alternative embodiments, a DC voltage may be applied to the upper electrode spray head 12.

[0041] Furthermore, in various embodiments, the amplitude of one or more RF signals (i.e., the first RF signal, the second RF signal, etc.) can be pulsed or modulated. Amplitude modulation can include pulsed RF signal amplitude between an on state and an off state, or between two or more different on states.

[0042] The exhaust system 40 may, for example, be connected to an exhaust port 10e located at the bottom of the plasma processing chamber 10. The exhaust system 40 may include a pressure valve and a vacuum pump. The vacuum pump may include a turbomolecular pump, a primary pump, or a combination thereof.

[0043] In one embodiment, the control unit 1b processes commands executed by a computer capable of causing the plasma processing apparatus 1a to perform the various processes described herein. The control unit 1b is configured to control the various elements of the plasma processing apparatus 1a in a manner that executes the various processes described herein. In one embodiment, part or all of the control unit 1b may be included in the plasma processing apparatus 1a. The control unit 1b may, for example, include a computer 51. The computer 51 may, for example, include a processing unit (CPU: Central Processing Unit) 511, a storage unit 512, and a communication interface 513. The processing unit 511 may be configured to perform various control actions based on programs stored in the storage unit 512. The storage unit 512 may include RAM (Random Access Memory), ROM (Read Only Memory), HDD (Hard Disk Drive), SSD (Solid State Drive), or combinations thereof. The communication interface 513 may communicate with the plasma processing apparatus 1a via a communication line such as a LAN (Local Area Network).

[0044] The above descriptions illustrate various implementation methods, but are not limited to these methods. Various additions, omissions, substitutions, and modifications are possible. Furthermore, elements from different implementation methods can be combined to form other implementation methods.

[0045] <Plasma Processing Methods>

[0046] Next, a plasma processing method including etching of substrate W using the plasma processing system 1 configured as described above will be described.

[0047] It should be noted that, in this embodiment, as Figure 3 As shown in (a), outside the plasma processing system 1, an STN film, an oxide film (Ox), and a SiN film, as the etching target layer, and a resist film (R) as the mask layer are stacked on the surface of the substrate W. For example, a polycrystalline silicon film can be selected as the resist film R. Furthermore, in the plasma processing system 1, as... Figure 3 As shown in (b), the resist film R with a pre-formed resist pattern is used as a mask to etch the STN film, oxide film Ox and SiN film, and the resist pattern is transferred to the substrate W.

[0048] In plasma processing, firstly, the substrate W is moved into the plasma processing chamber 10 and placed on the electrostatic chuck 112. Then, a DC voltage is applied to the lower electrode 111, causing the substrate W to be electrostatically attracted to and held by the electrostatic chuck 112 using Coulomb force. After the substrate W is moved in, the vacuum system 40 is used to reduce the pressure inside the plasma processing chamber 10 to the desired vacuum level.

[0049] Next, a processing gas (e.g., a mixture of CF4, CHF3, Ar, and O2) containing etching gas and dilution gas is supplied from the gas supply unit 20 to the plasma processing space 10s via the upper electrode spray head 12. Additionally, high-frequency power HF for plasma generation is supplied to the lower electrode 111 from the RF power supply unit 30, exciting the processing gas and generating plasma. Then, plasma etching is performed on the substrate W using the generated plasma. In this plasma etching process, as described above, the STN film, oxide film Ox, and SiN film are etched using the resist film R as a mask, and the resist pattern is transferred onto the substrate W ((A) Etching Step).

[0050] Here as Figure 1 As shown in (a), the resist pattern sometimes exhibits CD fluctuations due to the miniaturization of resist patterns in recent years. Furthermore, in cases where CD fluctuations occur, such as... Figure 1 As shown in (b), the amount of deposit D generated during the etching process fluctuates, resulting in, as Figure 1 As shown in (c), there is a concern about the deterioration of the surface morphology of the substrate W. Specifically, for example, in regions where the bars are coarse and the deposition of deposit D is abundant, the consumption of resist film R is low; conversely, in regions where the bars are fine and the deposition of deposit D is low, the consumption of resist film R is high. As a result, a difference in the height of resist film R during the etching process occurs. It should be noted that, in the following description, the portion of resist film R formed on the surface of the substrate W that has low consumption during the etching process and a high height position of the leading edge is sometimes referred to as "resist film Rh", and the portion that has high consumption and a low height position of the leading edge is sometimes referred to as "resist film Rl" (see reference). Figure 4 ).

[0051] Therefore, in the plasma processing according to this embodiment, when the surface morphology of the substrate W deteriorates during such etching process, a treatment to improve the surface morphology of the substrate W is performed. Specifically, as... Figure 4 As shown, after covering the morphologically deteriorated surface of the substrate W with a deposited capping layer DC as an accumulation ((B) deposited capping layer process), as... Figure 5 As shown, the surface of the substrate W covered by the deposited coating layer DC is etched ((C) finishing process).

[0052] In the deposition capping process, a processing gas (e.g., a mixture of C4F6, C3F8, NF3, and O2) for depositing the capping layer is supplied from the gas supply unit 20 to the plasma processing space 10s via the upper electrode spray head 12. Additionally, high-frequency power for plasma generation is supplied to the lower electrode 111 from the RF power supply unit 30, exciting the processing gas and generating plasma. Then, the deposit D generated by the plasma is deposited on the surface of the substrate W, thereby covering the surface with the deposition capping layer DC. It should be noted that the deposition capping layer DC is, for example, composed of a CF (fluorocarbon) based deposit D.

[0053] In this deposition coating process, on the surface of the morphologically deteriorated substrate W, the resist film Rh with a large height position at the front end becomes convex, and the resist film Rl with a small height position at the front end becomes concave, thus forming the deposition coating DC in a roughly mountain-like shape.

[0054] Here, in the deposition capping layer process of this embodiment, it is preferable to control the conditions (e.g., power, time) of the deposition capping layer process in such a way that the spacing of the resist pattern is completely blocked on at least the entire surface of the substrate W.

[0055] Furthermore, in the deposition coating process of this embodiment, it is desirable that at least within the surface of the substrate W, the front end surface of the resist film Rl ( Figure 4 The height H1) and the front end face of the resist film Rh ( Figure 4 The thickness of the sediment cover layer DC is formed above the height difference (H2-H1) of the height H2.

[0056] Furthermore, the thickness of the front end of the self-resistant film Rh of the formed deposit cover layer DC ( Figure 4 When the height H3 is large, the processing time consumed by subsequent finishing processes increases. Therefore, a smaller thickness H3 of the front face of the self-resistant film Rh of the deposit cover layer DC is preferred.

[0057] During the finishing process, a finishing gas (e.g., a mixture of C4F6, Ar, and O2) containing finishing gas and dilution gas is supplied from the gas supply unit 20 to the plasma processing space 10s via the upper electrode spray head 12. Additionally, high-frequency power for plasma generation is supplied to the lower electrode 111 via the RF power supply unit 30, exciting the finishing gas and generating plasma. Then, the substrate W is finished using the generated plasma.

[0058] In this finishing process, the surface of the substrate W is etched isotropically under enhanced side etching conditions, thereby finishing a portion of the deposited capping layer DC formed on the surface of the substrate W and the resist film R serving as a mask layer. The side etching components in the finishing process can be controlled, for example, by adjusting the processing pressure of the finishing process, the ratio of the diluent gas (Ar gas in this embodiment) mixed in the processing gas, or the power of the high-frequency power LF supplied from the RF power supply unit 30.

[0059] In this finishing process, firstly, as Figure 5 As shown in (a), the deposited capping layer DC formed on the surface of the substrate W is etched. At this time, trimming is performed under the condition of enhanced side etching as described above, so as to focus on etching the convex portion of the deposited capping layer DC.

[0060] During the etching of the deposited capping layer DC, the raised portions are ground down, thus... Figure 5 As shown in (b), the resist film Rh, which has a large height position on the front end face, is exposed from the deposit capping layer DC. Then, etching is continued in the above state, thereby etching the resist film Rh exposed along with the deposit capping layer DC, as shown... Figure 5 As shown in (c), the leading edge of the resist film R is uniformly high across the entire surface of the substrate W, thus planarizing the surface of the substrate W. That is, the morphology deteriorated during the etching process is improved.

[0061] After the morphology of the substrate W is improved, the etching process (A) continues. Then, when the transfer of the resist pattern to the etch target layer formed on the surface of the substrate W is completed, the etching process in the plasma processing system 1 is ended.

[0062] When the etching process is completed, firstly, the supply of high-frequency power (HF) from the RF power supply unit 30 and the supply of processing gas from the gas supply unit 20 are stopped. Additionally, if high-frequency power (LF) is supplied during plasma processing, the supply of that high-frequency power (LF) is also stopped. Then, the supply of thermally conductive gas to the back side of the substrate W is stopped, and the adsorption and holding of the substrate W based on the electrostatic chuck 112 is stopped.

[0063] The etched substrate W is then removed from the plasma processing chamber 10 and placed into an ashing apparatus (not shown) located outside the plasma processing system 1. In this ashing apparatus, the deposits D adhering to and remaining on the substrate W removed from the plasma processing system 1 are removed ((D) ashing process). The configuration of this ashing apparatus is not particularly limited; for example, it can be configured similarly to the plasma processing system 1. That is, in the ashing apparatus, the substrate W placed inside is excited by a processing gas for ashing, and ashing is performed using the generated plasma to remove the deposits D remaining on the substrate W.

[0064] Afterwards, the substrate W, which has undergone ashing treatment, is removed from the ashing device, and the series of plasma treatments on the substrate W is completed.

[0065] As described above in this embodiment, after covering the morphologically deteriorated surface of the substrate W with a deposited capping layer DC, a finishing process is performed on the resist film R on the deposited capping layer DC, thereby appropriately improving the surface morphology of the substrate W. Specifically, in the finishing process, the resist films Rh with the largest height position exposed from the front end face of the deposited capping layer DC are etched sequentially, and the resist film Rl with the smallest height position on the front end face is used as a reference to planarize the surface of the substrate W and improve its morphology.

[0066] Furthermore, during the finishing process, the deposition cap layer DC and the resist film R are etched under enhanced side etching conditions. Therefore, on the surface of the substrate W, at the corresponding position of the resist film Rh, which is formed in a convex shape, the etching of the deposition cap layer DC is actively carried out. In other words, the convex shape of the resist film Rh can be properly exposed, thus allowing the surface of the substrate W to be more appropriately planarized.

[0067] Furthermore, in this embodiment, the deposition capping layer process forms the deposition capping layer DC in a manner that completely blocks the spacing of the resist pattern across the entire surface of the substrate W, and an isotropic trimming process is performed on the surface of the substrate W. Therefore, trimming can be performed uniformly across the entire surface of the substrate W, and the influence on the spacing below the deposition capping layer DC, i.e., the pattern transferred onto the substrate W, can be appropriately suppressed.

[0068] Further according to this embodiment, such as Figure 4 As shown, a deposited capping layer DC is formed with a thickness at least equal to the height difference (H2-H1) between the front faces of the resist film Rl and the front faces of the resist film Rh. In other words, during the finishing process, the exposure of the pattern transferred to the substrate W below the deposited capping layer DC is suppressed, thus further suppressing any impact on the pattern.

[0069] Furthermore, in this process, the minimum resist film Rl at the height of the front end face is used as a reference, and only resist films R located closer to or above this front end face are removed. That is, the thickness of resist film R consumed in the process is minimized; specifically, resist film R is consumed only by the thickness of the height difference (H2-H1) between resist film Rh and resist film Rl, thereby improving the morphology of the substrate W. Therefore, the trade-off between morphological improvement and the etching selectivity of the mask layer, which has been a problem in previous morphological improvement methods, can be eliminated.

[0070] It should be noted that in the above embodiments, when the morphology deteriorates during the etching process (A), the deposition coating process (B) and the finishing process (C) are performed, but there is no particular limitation on the timing of these deposition coating process and finishing process.

[0071] For example, sediment cover layer processing and trimming processes, such as Figure 3 As shown, the etching can be performed after all the etching target layers (e.g., STN film, oxide film Ox and SiN film) formed on the surface of substrate W have been etched.

[0072] Furthermore, for example, after the etching of each etchable layer formed on the surface of the substrate W is completed, a deposition capping layer process and a finishing process can be performed. In other words, the etching process, the deposition capping layer process, and the finishing process can be repeated for each etchable layer.

[0073] Furthermore, for example, if the morphology of the substrate W is inspected simultaneously during the etching process, the deposition coating process and the finishing process can be performed sequentially when morphological deterioration is detected.

[0074] It should be noted that in the above embodiments, in the finishing process (C), the surface of the substrate W is etched isotropically under enhanced side etching conditions to finish the deposited capping layer DC. However, this finishing process can also etch the surface of the substrate W anisotropically. However, when the surface of the substrate W is etched anisotropically, the sputtering on that surface is strong, which raises concerns about consuming the resist film R, which serves as a mask layer. That is, considering the aspect of minimizing the consumption of the mask layer to achieve morphological improvement, the finishing process preferably etches the surface of the substrate W isotropically.

[0075] It should be noted that in the above embodiments, the case in which an STN film, an oxide film Ox, and a SiN film are formed on the substrate W is used as the etching target layer for illustration. However, the type and number of layers of the etching target layer are not limited to this and can be arbitrarily determined.

[0076] Furthermore, this embodiment describes the case where a resist film R comprising a polycrystalline silicon film is used as a mask layer, but the type and number of mask layers are not limited to this. Moreover, the hardness of the resist film R can be improved by doping it with at least one of W (tungsten) and B (boron). Improving the hardness of the resist film R in this way reduces the consumption during the etching process, i.e., it improves the selectivity for the target layer being etched.

[0077] Furthermore, in this embodiment, a deposit cover layer DC containing CF-based deposits is formed on the surface of the substrate W, but the type of deposit cover layer DC is not limited to this.

[0078] It should be noted that the plasma processing system 1 of the above embodiments has a capacitively coupled plasma processing device, but the plasma processing system used in this disclosure is not limited to this. For example, the plasma processing system may have an inductively coupled plasma processing device. The plasma processing system can have any system configuration, as long as the etching method of this embodiment is used, the above-mentioned effects can be enjoyed.

[0079] The embodiments disclosed herein are illustrative in all respects and should be considered without limitation. The above embodiments may be omitted, substituted, or modified in various forms without departing from the appended claims and their spirit.

[0080] Example

[0081] The following describes embodiments of the technology involved in this disclosure, but the technology is not limited to the following embodiments.

[0082] <Implementation Conditions>

[0083] like Figure 3 As shown in (a), for a substrate W formed by stacking an STN film, an oxide film Ox and a SiN film as etching target layers, and a resist film R as a mask layer on the surface, as Figure 3 As shown in (b), after transferring the resist pattern using the resist film R as a mask (etching process), a deposition coating process and a finishing process are performed to improve the morphology.

[0084] Specifically, in the sediment capping process, plasma treatment is performed using a sediment capping treatment gas containing more than 50% C4F6 of the total flow rate, and in the trimming process, plasma treatment is performed using a trimming treatment gas containing more than 80% Ar of the total flow rate.

[0085] <Implementation Results>

[0086] Figure 6 The explanatory diagrams illustrating the results of this embodiment show (a) the state before and after ashing after the etching process and before the deposition coating process and the trimming process, (b) the state before and after ashing after the deposition coating process and after a 2-minute trimming process, and (c) the state before and after ashing after the deposition coating process and after a 4-minute trimming process.

[0087] like Figure 6 As shown in (a), the height of the resist film R fluctuates and its morphology deteriorates after the etching process and before the deposition coating process and the finishing process. Specifically, the minimum height of the resist film R remaining on the substrate W is about 105 nm, the maximum height is about 120 nm, and the average height of the resist film R remaining is about 115 nm.

[0088] right Figure 6 (a) After the etching process shown, a deposited capping layer DC is formed on the substrate W. A 2-minute finishing process is then performed, and the result is as follows: Figure 6 As shown in (b), the height of the resist film R is homogenized, and the morphology is improved. At this time, the average residual film height of the resist film R is about 105 nm, which means that about 10 nm of the resist film R is consumed during the finishing process.

[0089] Furthermore, further finishing processes were carried out, and the results were as follows: Figure 6 As shown in (c), the height of the resist film R is further homogenized, and its morphology is further improved. At this point, the average residual film height of the resist film R is approximately 100 nm. That is, it can be seen that the total amount of resist film R consumed in the finishing process is... Figure 6 (a) shows that the difference between the minimum and maximum height of the resist film R remaining on the substrate W, i.e., 15 nm, is approximately the same.

[0090] The results above show that when the morphology of the substrate W deteriorates during the etching process, a deposited capping layer DC is formed on the surface of the substrate W (deposit capping layer process). Further etching is then performed on the deposited capping layer DC (trimming process), which can appropriately improve the deteriorated morphology. Moreover, at this time, the difference between the minimum and maximum height of the resist film R consumed in the trimming process and the resist film R remaining on the substrate W after the etching process is approximately the same, that is, the consumption of the resist film R can be minimized.

Claims

1. An etching method for etching a workpiece having an etchable object layer formed on its surface and a mask layer formed on top of the etchable object layer and pre-patterned thereon, the etching method comprising the following steps: Step (A): Using the mask layer as a mask, the etchable layer is etched. Step (B), covering the surface of the object being processed with a buildup; and, Step (C) involves etching the surface of the object being processed, which is covered by the deposit, to planarize the surface. in, The etched object layer is stacked and formed on the surface of the object being processed. For each layer of the etched object that is stacked and formed, the processes (A), (B), and (C) are repeated.

2. The etching method according to claim 1, wherein, It also includes the following step (D): removing the deposits from the surface of the object being processed.

3. The etching method according to claim 1 or 2, wherein, When the flatness of the surface of the object being processed in step (A) is detected to be deteriorated, steps (B) and (C) are performed.

4. The etching method according to claim 1 or 2, wherein, In step (C), the surface of the object being processed is etched isotropically.

5. The etching method according to claim 1 or 2, wherein, The deposit is a sediment containing fluorinated carbon polymers.

6. The etching method according to claim 1 or 2, wherein, The etched layer is a silicon-containing film.

7. The etching method according to claim 1 or 2, wherein, The mask layer is an anti-corrosion film.

8. The etching method according to claim 7, wherein, The resist film is a polycrystalline silicon film.

9. The etching method according to claim 7, wherein, The step includes doping the resist film with at least one of tungsten or boron.

10. An etching method for etching a processed object having an etchable object layer formed on its surface and a mask layer formed on top of the etchable object layer and pre-patterned thereon, the etching method comprising the following steps: Step (A): Using the mask layer as a mask, the etchable layer is etched. Step (B), covering the surface of the object being processed with a buildup; and, Step (C) involves etching the surface of the object being processed, which is covered by the deposit, to planarize the surface. in, When the flatness of the surface of the object being processed in step (A) is detected to be deteriorated, steps (B) and (C) are performed.

11. An etching method for etching a workpiece having an etchable object layer formed on its surface and a mask layer formed on top of the etchable object layer and pre-patterned thereon, the etching method comprising the following steps: Step (A): Using the mask layer as a mask, the etchable layer is etched. Step (B), covering the surface of the object being processed with a buildup; and, Step (C) involves etching the surface of the object being processed, which is covered by the deposit, to planarize the surface. in, The deposit is a sediment containing fluorinated carbon polymers.

12. A plasma processing system for performing plasma processing on a processing object having an etchable object layer formed on its surface and a mask layer formed on a layer above the etchable object layer and pre-patterned thereon. The plasma processing system comprises: A chamber, which is used to divide the processing space for generating plasma; A stage, disposed inside the chamber, is used to hold the object to be processed; An exhaust unit that vents air from the interior of the chamber; A gas supply unit supplies processing gas to the interior of the chamber; and, A control unit, which controls the plasma processing inside the chamber, The control unit controls the plasma treatment by performing the following steps on the object to be treated: Step (A): Using the mask layer as a mask, the etchable layer is etched. Step (B): Cover the surface of the object being processed with a buildup; and Step (C) involves etching the surface of the object being processed, which is covered by the deposit, to planarize the surface. The etched object layer is stacked and formed on the surface of the object being processed. The control unit controls the plasma processing by repeating the process (A), process (B), and process (C) for each layer of the etched object that is stacked and formed.

13. The plasma processing system according to claim 12, wherein, The control unit controls the plasma treatment in a manner that also performs the following step (D): removing the deposits from the surface of the object being treated.

14. The plasma processing system according to claim 12 or 13, wherein, The control unit controls the plasma treatment in such a way that when the flatness of the surface of the object being treated is detected to deteriorate in step (A), steps (B) and (C) are performed.

15. The plasma processing system according to claim 12 or 13, wherein, The control unit controls the plasma treatment in such a way that the surface of the object to be treated is etched isotropically in the process (C).

16. The plasma processing system according to claim 12 or 13, wherein, The deposit is a sediment containing fluorinated carbon polymers.

17. The plasma processing system according to claim 12 or 13, wherein, The etched layer is a silicon-containing film.

18. The plasma processing system according to claim 12 or 13, wherein, The mask layer is an anti-corrosion film.

19. The plasma processing system according to claim 18, wherein, The resist film is a polycrystalline silicon film.

20. The plasma processing system according to claim 18, wherein, The resist film contains a substance doped with at least one of tungsten or boron.

21. A plasma processing system for performing plasma processing on a processing object having an etchable object layer formed on its surface and a mask layer formed on a layer above the etchable object layer and pre-patterned thereon. The plasma processing system comprises: A chamber, which is used to divide the processing space for generating plasma; A stage, disposed inside the chamber, is used to hold the object to be processed; An exhaust unit that vents air from the interior of the chamber; A gas supply unit supplies processing gas to the interior of the chamber; and, A control unit, which controls the plasma processing inside the chamber, The control unit controls the plasma treatment by performing the following steps on the object to be treated: Step (A): Using the mask layer as a mask, the etchable layer is etched. Step (B): Cover the surface of the object being processed with the accumulated material; and Step (C) involves etching the surface of the object being processed, which is covered by the deposit, to planarize the surface. The control unit controls the plasma treatment in such a way that when the flatness of the surface of the object being treated in step (A) is detected to be deteriorated, steps (B) and (C) are performed.

22. A plasma processing system for performing plasma processing on a processing object having an etchable object layer formed on its surface and a mask layer formed on a layer above the etchable object layer and pre-patterned thereon. The plasma processing system comprises: A chamber, which is used to divide the processing space for generating plasma; A stage, disposed inside the chamber, is used to hold the object to be processed; An exhaust unit that vents air from the interior of the chamber; A gas supply unit supplies processing gas to the interior of the chamber; and, A control unit, which controls the plasma processing inside the chamber, The control unit controls the plasma treatment by performing the following steps on the object to be treated: Step (A): Using the mask layer as a mask, the etchable layer is etched. Step (B): Cover the surface of the object being processed with a buildup; and Step (C) involves etching the surface of the object being processed, which is covered by the deposit, to planarize the surface. The deposit is a sediment containing fluorinated carbon polymers.

23. A plasma processing system for performing plasma processing on a processing object having an etchable object layer formed on its surface and a mask layer formed on a layer above the etchable object layer and pre-patterned thereon. The plasma processing system comprises: A chamber, which is used to divide the processing space for generating plasma; A stage, disposed inside the chamber, is used to hold the object to be processed; An exhaust unit that vents air from the interior of the chamber; A gas supply unit supplies processing gas to the interior of the chamber; and, A control unit, which controls the plasma processing inside the chamber, The control unit controls the plasma treatment by performing the following steps on the object to be treated: Step (A): Using the mask layer as a mask, the etchable layer is etched. Step (B): Cover the surface of the object being processed with a buildup; and Step (C) involves etching the surface of the object being processed, which is covered by the deposit, to planarize the surface. The mask layer is a resist film, and the resist film is a polycrystalline silicon film.

24. A plasma processing system for performing plasma processing on a processing object having an etchable object layer formed on its surface and a mask layer formed on a layer above the etchable object layer and pre-patterned thereon. The plasma processing system comprises: A chamber, which is used to divide the processing space for generating plasma; A stage, disposed inside the chamber, is used to hold the object to be processed; An exhaust unit that vents air from the interior of the chamber; A gas supply unit supplies processing gas to the interior of the chamber; and, A control unit, which controls the plasma processing inside the chamber, The control unit controls the plasma treatment by performing the following steps on the object to be treated: Step (A): Using the mask layer as a mask, the etchable layer is etched. Step (B): Cover the surface of the object being processed with a buildup; and Step (C) involves etching the surface of the object being processed, which is covered by the deposit, to planarize the surface. The mask layer is a resist film, which contains a substance doped with at least one of tungsten or boron.

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