Pattern forming method and pattern forming apparatus

Abstract

Provided is a pattern forming method comprising: preparing a substrate having a second conductive layer on a surface of a substrate on which a pattern of a first conductive layer and an insulating layer is formed; supplying an ionic liquid to the surface of the substrate; and forming a pattern of the second conductive layer on the first conductive layer by supplying a current to the first conductive layer to which the ionic liquid is supplied.

Description

Pattern forming method and pattern forming apparatus

[0001] The present disclosure relates to a pattern forming method and a pattern forming apparatus.

[0002] For example, Patent Document 1 discloses a method for forming a Ru film or RuO by the following steps: ２ First, a Ru film or RuO film is formed on a Si substrate. ２ After forming a film by sputtering, an SOG film is applied, a photosensitive material is applied, and a resist pattern is formed using an exposure device. Next, the SOG film is patterned using an ECR dry etching device. After that, the resist pattern is peeled off by oxygen plasma ashing, and an etching mask of the SOG film is formed, and a Ru film or RuO ２ The film is processed into a desired pattern using a mixed gas plasma of oxygen and chlorine.

[0003] Japanese Patent Application Publication No. 8-078396

[0004] The present disclosure provides a technology that can form a pattern of a second conductive layer on a substrate on which a pattern of a first conductive layer and an insulating layer is formed, by utilizing the difference in adhesion between the layers.

[0005] According to one aspect of the present disclosure, there is provided a pattern forming method comprising: preparing a substrate having a second conductive layer on a surface of a substrate on which a pattern of a first conductive layer and an insulating layer is formed; supplying an ionic liquid to the surface of the substrate; and forming a pattern of the second conductive layer on the first conductive layer by passing an electric current through the first conductive layer to which the ionic liquid has been supplied.

[0006] According to one aspect, in a substrate on which a pattern of a first conductive layer and an insulating layer is formed, a pattern of a second conductive layer can be formed on the first conductive layer by utilizing the difference in adhesion between the layers.

[0007] FIG. 1 shows an example of an experimental result of pattern formation on a substrate using an ionic liquid according to an embodiment. FIG. 2 shows another example of pattern formation on a substrate using an ionic liquid according to an embodiment. FIG. 3 is a schematic diagram showing an example of a pattern formation apparatus according to a first embodiment. FIG. 4 is a diagram showing an example of pattern formation of a metal layer by the pattern formation apparatus of FIG. 3. FIG. 5 is a schematic diagram showing an example of a pattern formation apparatus according to a second embodiment. FIG. 6 is a diagram showing an example of pattern formation of a metal layer by the pattern formation apparatus of FIG. 5. FIG. 7 is a flowchart showing an example of a pattern formation method using the pattern formation apparatus according to the first embodiment. FIG. 8 is a diagram showing an example of application of the pattern formation method according to the first embodiment to a process. FIG. 9 is a flowchart showing an example of a pattern formation method using the pattern formation apparatus according to the second embodiment. FIG. 9 is a diagram showing an example of application of the pattern formation method according to the second embodiment to a process. FIG. 10 is a diagram showing an example of application of the pattern formation method according to the second embodiment to a process. FIG. 11 is a diagram showing an example of application of the pattern formation method according to the second embodiment to a process. FIG. 12 is a diagram showing another example of application of the pattern formation method according to the second embodiment to a process. FIG. 13 is a diagram showing another example of application of the pattern formation method according to the second embodiment to a process. FIG. 14 is a diagram showing another example of application of the pattern formation method according to the second embodiment to a process.

[0008] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant explanations may be omitted.

[0009] [Patterning on a Substrate Using an Ionic Liquid] An example of experimental results of patterning a conductive layer on a substrate using an ionic liquid according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a diagram showing an example of experimental results of patterning on a substrate using an ionic liquid according to an embodiment.

[0010] (a) of Fig. 1 is a top view of the laminate of films on the substrate before the experiment. (c) of Fig. 1 is a diagram showing the A-A cross section of the laminate of Fig. 1(a). (b) of Fig. 1 is a top view of the laminate of films on the substrate after the experiment. (e) of Fig. 1 is a diagram showing the B-B cross section of the laminate of Fig. 1(b). (d) of Fig. 1 is a cross section of the laminate during the experiment. (c) of Fig. 1 is a diagram showing the A-A cross section of the laminate during the experiment.

[0011] In the experiment, as shown in (c) to (e) of FIG. 1, SiO ２ A laminate in which a first conductive layer 102 such as TiN is embedded in a recess of an insulating layer 101 such as a low-k material and a second conductive layer 103 such as Ru is formed on the first conductive layer 102 is immersed in ionic liquid I of EMIM.

[0012] In this state, a current was applied from the power supply 215 to the first conductive layer 102 via the ionic liquid I. As a result, the ionic liquid I, which has a tendency to easily penetrate, entered between the insulating layer 101 and the second conductive layer 103, causing the second conductive layer 103 on the insulating layer 101 to peel off.

[0013] Specifically, when one electrode connected to a power supply 215 is inserted into the ionic liquid I and the other electrode is brought into contact with the first conductive layer 102 to pass a current, cations (positive ions) and anions (negative ions) in the ionic liquid I are attracted to the periphery of the first conductive layer 102, as shown in (c) of Figure 1. The first conductive layer 102 and the second conductive layer 103 are the same conductor, and the interface between them has higher adhesion than the interface between the insulating layer 101 and the second conductive layer 103.

[0014] Therefore, as shown in (d) of FIG. 1 , cations and anions penetrated into the interface between the insulating layer 101 and the second conductive layer 103, which has lower adhesion than the interface between the first conductive layer 102 and the second conductive layer 103, and as a result, the second conductive layer 103 peeled off from the insulating layer 101. Cations and anions could not penetrate into the interface between the first conductive layer 102 and the second conductive layer 103, which has good adhesion, and peeling did not occur. As a result, as shown in (e) of FIG. 1 , peeling of the second conductive layer 103 from the insulating layer 101 selectively left only the second conductive layer 103 on the first conductive layer 102, which has good adhesion, and a pattern of the second conductive layer 103 could be formed.

[0015] With another film deposited on the second conductive layer 103, the second conductive layer 103 and the other film can be peeled off at once from the interface with the insulating layer 101, thereby forming a pattern of the second conductive layer 103 and the other film. Figure 2 shows another example of pattern formation on a substrate using an ionic liquid. For example, in Figure 2(a), another film 104 is formed on the second conductive layer 103. The film 104 may be a metal film or an insulating film. The adhesion between the film 104 and the second conductive layer 103 is not important. By performing an experiment using the same ionic liquid as in the experiment of Figure 1 on the structure of Figure 2(a), the second conductive layer 103 and the other film 104 on the insulating layer 101 are both peeled off. As a result, as shown in (b) of Figure 2, only the second conductive layer 103 and film 104 on the first conductive layer 102, which has good adhesion, are selectively left, and the second conductive layer 103 and film 104 on the insulating layer 101, which has poor adhesion, are peeled off in one go, and the second conductive layer 103 and film 104 can be formed in the pattern of the first conductive layer 102.

[0016] The second conductive layer 103 may be any of a noble metal, tungsten, molybdenum, or copper (Cu). The second conductive layer 103 may also be any of a noble metal, such as gold (Au), silver (Ag), platinum (Pt), palladium (Pd), rhodium (Rh), iridium (Ir), ruthenium (Ru), or osmium (Os).

[0017] In particular, noble metals are difficult to process by wet etching and even by dry etching. When dry etching the second conductive layer 103 made of a noble metal, the etching is performed by irradiating plasma. Therefore, the SiO 2 layer under the substrate and the second conductive layer 103 is likely to be slightly damaged. ２In contrast, the present pattern formation method does not irradiate plasma, resulting in minimal damage to the insulating layer 101. Furthermore, lift-off of the second conductive layer 103 from the insulating layer 101 facilitates pattern formation of materials such as precious metals, which are difficult to pattern by etching. Furthermore, the present pattern formation method does not involve the concept of selectivity, and even if the second conductive layer 103 is made of a material that does not achieve a selectivity in plasma etching, it is possible to form a pattern by utilizing the difference in adhesion between layers. This allows the second conductive layer 103 to be patterned simply by immersing a substrate having the second conductive layer 103 on the surface of a substrate on which a pattern of the first conductive layer 102 and the insulating layer 101 has been formed in ionic liquid I and controlling the current. This eliminates the need for a separate patterning process for the second conductive layer 103, as in the conventional method.

[0018] Furthermore, after this experiment, a film of the second conductive layer 103 was found floating in the ionic liquid I. Therefore, it is believed that the second conductive layer 103 was peeled off rather than dissolved. In other words, the second conductive layer 103 underwent a chemical reaction and remained in the ionic liquid as its original metal or the like, rather than as a by-product that had been altered. Therefore, according to this pattern formation method, the peeled second conductive layer 103 in the ionic liquid I can be recovered and reused.

[0019] First Embodiment [Pattern Forming Apparatus] Next, an example of a pattern forming apparatus that performs a pattern formation method using ionic liquid I will be described with reference to Fig. 3 and Fig. 4. Fig. 3 is a schematic diagram showing an example of a pattern forming apparatus 200 according to the first embodiment. Fig. 4 is a diagram showing an example of pattern formation of a metal layer using the pattern forming apparatus 200 of Fig. 3. In the first embodiment, as shown in Fig. 4, a pattern forming system 400 is configured by a film forming apparatus 300 and the pattern forming apparatus 200.

[0020] 4A has a structure in which a low-k film 112 is formed on a silicon substrate 111, and a first metal film 113 is embedded in the recesses of the low-k film 112. The low-k film 112 is an example of an insulating layer. The first metal film 113 is, for example, a metal wiring, and is an example of a first conductive layer. The first metal film 113 may be made of Ti, TiN, TaN, or the like.

[0021] The substrate W on which such a pattern of the low-k film 112 and the first metal film 113 has been formed is transported to a film forming apparatus 300. The film forming apparatus 300 forms a second metal film 114 on the surface of the substrate W. The second metal film 114 is, for example, metal wiring and is an example of a second conductive layer. The second metal film 114 may be made of Ru, Pt, Cu, W, Mo, or the like. The film forming apparatus 300 may be a physical vapor deposition (PVD) apparatus, a chemical vapor deposition (CVD) apparatus, an atomic layer deposition (ALD) apparatus, or the like. The film forming apparatus 300 may also be a plasma processing apparatus such as a capacitively coupled plasma (CCP) apparatus or an inductively coupled plasma (ICP) apparatus.

[0022] 4(b), a second metal film 114 is formed on the pattern of the first metal film 113 and the low-k film 112 on the substrate W. The substrate W, which has the second metal film 114 on the surface of the substrate W on which the pattern of the first metal film 113 and the low-k film 112 has been formed, is carried into a pattern forming apparatus 200, where the pattern of the second metal film 114 is formed. The pattern forming apparatus 200 of FIG. 3 is an example of an apparatus that forms a pattern of the second metal film 114. The pattern forming apparatus 200 has a chamber 210, a liquid supply unit 220, a liquid circulation unit 230, and a control unit 290.

[0023] The chamber 210 forms a sealed processing space 211. The inside of the chamber 210 is evacuated by an exhaust system (not shown) including a pressure control valve, a vacuum pump, etc., and is maintained in a vacuum state (reduced pressure state). Alternatively, the inside of the chamber 210 is filled with N 2 supplied from an inert gas supply unit (not shown). ２The chamber may be filled with an inert gas such as a gas, and may be in an inert gas atmosphere.

[0024] A processing tank 212 is provided within the chamber 210. The substrate W transported into the chamber 210 is stored inside the processing tank 212. An insulating holding jig 214 is arranged on the outer periphery of the bottom surface of the processing tank 212. The holding jig 214 holds the substrate W in a substantially horizontal position.

[0025] The liquid supply unit 220 may include a slit nozzle 221. The slit nozzle 221 supplies the ionic liquid I into the treatment tank 212. This causes the substrate W to be immersed in the ionic liquid I stored in the treatment tank 212. Note that the supply of the ionic liquid includes both immersion and application. The liquid supply unit 220 does not necessarily have to be the slit nozzle 221, and may be a simple nozzle.

[0026] The liquid circulation unit 230 recovers the ionic liquid stored in the treatment tank 212 and supplies it to the slit nozzle 221. The liquid circulation unit 230 includes a compressor 231, an ionic liquid tank 232, a carrier gas supply source 233, a cleaning unit 234, and pH sensors 235 and 236.

[0027] The compressor 231 is connected to the treatment tank 212 via a pipe 239a, and recovers the ionic liquid I stored in the treatment tank 212 and compresses it, for example, to atmospheric pressure or higher. The compressor 231 is connected to the ionic liquid tank 232 via a pipe 239b, and transports the compressed ionic liquid to the ionic liquid tank 232 via the pipe 239b. The ionic liquid tank 232 stores the ionic liquid. For example, a valve and a flow rate controller (neither of which are shown) are installed in the pipe 239b. For example, the ionic liquid is periodically transported from the compressor 231 to the ionic liquid tank 232 by controlling the opening and closing of the valve.

[0028] One end of pipes 239b to 239d is inserted into ionic liquid tank 232. The other end of pipe 239b is connected to compressor 231, and ionic liquid compressed by compressor 231 is supplied to ionic liquid tank 232 via pipe 239b. The other end of pipe 239c is connected to carrier gas supply source 233, and N2 gas is supplied to ionic liquid tank 232 from carrier gas supply source 233 via pipe 239c. ２ A carrier gas such as N gas is supplied to the ionic liquid tank 232. ２ By bubbling the gas, an ionic liquid with reduced dissolved oxygen can be supplied into the treatment tank 212. Instead of bubbling in the ionic liquid tank 232, the ionic liquid in the treatment tank 212 can be supplied with N ２ Dissolved oxygen may be reduced by bubbling. ２ Bubbling can improve the quality of the ionic liquid I. However, if nitrogen (N ２ ) gas or other carrier gas may not be supplied.

[0029] The other end of pipe 239d is connected to slit nozzle 221, and the ionic liquid in ionic liquid tank 232 is transported together with the carrier gas via pipe 239d to slit nozzle 221. Pipes 239b to 239d are provided with, for example, valves and flow rate controllers (neither of which is shown).

[0030] The recovery filter 240 and the cleaning unit 234 are interposed in the pipe 239b. The recovery filter 240 is disposed closer to the compressor 231 than the cleaning unit 234, and recovers the second metal film 114 in the ionic liquid I transported from the compressor 231. The second metal film 114 peeled off in the treatment tank 212 can be recovered by the recovery filter 240 and reused.

[0031] The cleaning unit 234 cleans the ionic liquid after recovering the second metal film 114. A drain pipe 239e is connected to the cleaning unit 234, and the ionic liquid with deteriorated properties is discharged via the drain pipe 239e. For example, the cleaning unit 234 controls whether to reuse or discharge the ionic liquid based on the detection value of the pH sensor 236. Furthermore, for example, the cleaning unit 234 may control whether to reuse or discharge the ionic liquid based on the detection value of the pH sensor 235. Furthermore, for example, the cleaning unit 234 may control whether to reuse or discharge the ionic liquid based on the detection values ​​of the pH sensors 235 and 236.

[0032] The pH sensor 235 is provided in the compressor 231 and detects the hydrogen ion exponent (pH) of the ionic liquid in the compressor 231 .

[0033] The pH sensor 236 is provided in the cleaning section 234 and detects the hydrogen ion exponent (pH) of the ionic liquid in the cleaning section 234 .

[0034] The control unit 290 performs a pattern formation process based on a computer-executable program to be executed by the pattern formation device 200. The control unit 290 can be configured to control each element of the pattern formation device 200 so as to perform pattern formation of a metal film by immersing the ionic liquid I. The control unit 290 includes, for example, a computer. The computer includes, for example, a CPU, a storage unit, and a communication interface.

[0035] The pattern forming device 200 has a power supply 215 and electrodes 216 and 217 connected to the power supply 215. One electrode 217 is inserted into ionic liquid I. A probe (needle) at the tip of the other electrode 216 is brought into contact with the second metal film 114 directly above the first metal film 113 of the substrate W, as shown in FIG. 4C , while the position of the probe is monitored by a camera 218. The camera 218 may monitor the position of the probe from outside the chamber 210.

[0036] The camera 218 may detect the position of the first metal film 113 before depositing the second metal film 114. In this case, after depositing the second metal film 114, the probe at the tip of the electrode 216 is brought into contact with the second metal film 114 directly above the first metal film 113 based on the detected position of the first metal film 113.

[0037] Because the second metal film 114 is a thin film, the camera 218 may detect the position of the first metal film 113 after forming the second metal film 114. In this case as well, the probe at the tip of the electrode 216 is brought into contact with the second metal film 114 directly above the first metal film 113 based on the detected position of the first metal film 113.

[0038] The camera 218 may monitor a notch formed in the substrate W and predict the position of the first metal film 113 from the position of the notch. Alignment marks may be attached to the substrate in advance, and the camera 218 may predict the position of the first metal film 113 from the positions of the alignment marks on the substrate. In these cases, based on the predicted position of the first metal film 113, the probe at the tip of the electrode 216 is brought into contact with the second metal film 114 directly above the first metal film 113.

[0039] The position of the first metal film 113 may be detected by the camera 218 before the ionic liquid I is supplied to the treatment tank 212. The position of the first metal film 113 may be detected by the camera 218 after the ionic liquid I is supplied to the treatment tank 212.

[0040] An electric current is passed from the power supply 215 to the first metal film 113 via the ionic liquid I and the second metal film 114. As a result, due to the difference in adhesion between the low-k film 112 and the second metal film 114 and the adhesion between the first metal film 113 and the second metal film 114, the second metal film 114 on the low-k film 112 is peeled off from the surface of the substrate W. As a result, as shown in FIG. 4C , the second metal film 114 remains only directly above the first metal film 113, and a pattern of the second metal film 114 is formed.

[0041] In the backend of a semiconductor pre-process, the substrate W has a structure in which an insulating film such as a low-k film 112 is sandwiched between a silicon substrate 111 and a first metal film 113. In this case as well, in the pattern forming apparatus 200 shown in FIG. 3, one electrode is inserted into the ionic liquid and the other electrode is brought into contact with the surface of the substrate W, thereby allowing a current to flow through the first metal film 113.

[0042] Second Embodiment [Pattern Forming Apparatus] Next, another example of a pattern forming apparatus for performing a pattern formation method using ionic liquid I will be described with reference to Figs. 5 and 6. Fig. 5 is a schematic diagram showing an example of a pattern forming apparatus 200a according to a second embodiment. Fig. 6 is a diagram showing an example of metal layer pattern formation using the pattern forming apparatus 200a of Fig. 5. In the second embodiment, as shown in Fig. 6, a pattern forming system 400a is configured by a film forming apparatus 300 and the pattern forming apparatus 200a.

[0043] 6A, a substrate W has a pattern of a low-k film 112 and a first metal film 113 formed on a silicon substrate 111. The substrate W on which such a pattern of the low-k film 112 and the first metal film 113 has been formed is transported to a film forming apparatus 300. The film forming apparatus 300 forms a second metal film 114 on the surface of the substrate W.

[0044] As a result, as shown in (b) of Fig. 6, a second metal film 114 is formed on the surface of the substrate W on which the first metal film 113, the low-k film 112, and the pattern have been formed. The substrate W on which the second metal film 114 has been formed is carried into the pattern forming apparatus 200a of Fig. 5. The pattern forming apparatus 200a of Fig. 5 has a chamber 210, a liquid supply unit 220, a liquid circulation unit 230, and a control unit 290.

[0045] The configurations of the chamber 210, liquid supply unit 220, liquid circulation unit 230, and control unit 290 of the pattern formation apparatus 200a in Fig. 5 are the same as the corresponding configurations of the pattern formation apparatus 200 in Fig. 3, and therefore will not be described. Below, a description will be given of the processing tank 212a, power supply unit 215, and electrodes 216 and 217, which have different configurations or arrangements from the pattern formation apparatus 200 in Fig. 3. Note that the pattern formation apparatus 200a in Fig. 5 does not require a structure such as a camera 218 for monitoring the probe position of the electrode 216.

[0046] The processing tank 212a is provided on its bottom with a metal plate 213. The metal plate 213 is in contact with the rear surface of the substrate W and serves to electrically connect the rear surface of the substrate W to an electrode 216 connected to a power supply unit 215.

[0047] In the pattern forming device 200a, one electrode 217 is inserted into the ionic liquid I. A metal mesh plate 219 is provided in the ionic liquid I, and the electrode 217 is brought into contact with the plate 219. However, the plate 219 may not be provided, and the electrode 217 may be inserted into the ionic liquid I, as in the electrode 217 shown in FIG. 3. The probe (needle) at the tip of the other electrode 216 is brought into contact with the back surface of the metal plate 213.

[0048] The power supply device 215 applies electricity to the first metal film 113 via the ionic liquid I. In this embodiment, as shown in FIG. 6B , the front and back surfaces of the substrate W are electrically connected via the silicon substrate 111, the first metal film 113, and the second metal film 114. Therefore, by bringing the probe at the tip of the electrode 216 into contact with the metal plate 213, electricity can be applied to the first metal film 113 via the ionic liquid I.

[0049] As a result, due to the difference in adhesion between the low-k film 112 and the second metal film 114 and the adhesion between the first metal film 113 and the second metal film 114, the second metal film 114 on the low-k film 112 is peeled off from the surface of the substrate W. As a result, as shown in Figure 6(c), the second metal film 114 remains only directly above the first metal film 113, and a pattern of the second metal film 114 is formed.

[0050] In this way, when electrical continuity can be established between the front and rear surfaces of the substrate W, the pattern of the second metal film 114 can be formed using the pattern forming apparatus 200a according to the second embodiment.

[0051] In the case of the front end of a semiconductor pre-process, the substrate W is a structure in which electrical continuity can be established between the front and back surfaces of the substrate W. In this case, using the pattern formation device 200a shown in Figure 5, one electrode is inserted into the ionic liquid and the other electrode is brought into contact with the metal plate 213, thereby allowing a current to flow through the first metal film 113. Note that, when electrical continuity can be established between the front and back surfaces of the substrate W, a current can also be passed through the first metal film 113 using the pattern formation device 200 shown in Figure 3.

[0052] [Pattern Forming Method Using Pattern Forming Apparatus According to First Embodiment] An example of a pattern forming method using the pattern forming apparatus 200 according to the first embodiment will be described with reference to Fig. 7. Fig. 7 is a flowchart showing an example of a pattern forming method using the pattern forming apparatus 200 according to the first embodiment. The pattern forming method of Fig. 7 is controlled by a control unit 290.

[0053] In the pattern forming method of FIG. 7, in step S1, a substrate W is prepared which has a second conductive layer on the surface of the substrate W on which a pattern of a first conductive layer and an insulating layer has been formed.

[0054] In step S2, the position of the first conductive layer is monitored using the camera 218. In step S3, an ionic liquid is supplied to the treatment bath 212, and the surface of the substrate W is immersed in the ionic liquid.

[0055] In step S4, the probe at the tip of electrode 216 connected to power supply 215 is brought into contact with the second conductive layer immediately above the first conductive layer based on the monitored position of the first conductive layer. The other electrode 217 connected to power supply 215 is immersed in the ionic liquid.

[0056] In step S5, a current is passed from the power supply 215 to the first conductive layer via the ionic liquid I. As a result, in step S6, the second conductive layer on the insulating layer is peeled off from the surface of the substrate W due to the difference in adhesion between the insulating layer and the second conductive layer and the adhesion between the first conductive layer and the second conductive layer. As a result, the second conductive layer remains only on the first conductive layer, and a pattern of the second conductive layer can be formed.

[0057] 8A and 8B show an example of application of the pattern formation method according to the first embodiment to a process. As shown in FIG. 8A , the substrate W to be prepared has an insulating layer 620 formed on a silicon substrate 600, and first conductive layers 610A and 610B embedded in recesses in the insulating layer 620. The first conductive layers 610A and 610B are formed in parallel. Second conductive layers 630A and 630B are formed on the patterns of the first conductive layers 610A and 610B and the insulating layer 620. The first conductive layers 610A and 610B and the second conductive layers 630A and 630B are, for example, metal wiring.

[0058] In steps S1 and S3, an ionic liquid is supplied to the surface of the prepared substrate W. In steps S2 and S4, based on the positions of the first conductive layers 610A and 610B monitored by the camera 218, a probe at the tip of the electrode 216 connected to the power supply device 215 is brought into contact with the second conductive layers 630A and 630B directly above the first conductive layers 610A and 610B. In step S5, a current is passed from the power supply device 215 to the first conductive layers 610A and 610B via the ionic liquid.

[0059] In step S6, due to the difference in adhesion between the insulating layer 620 and the second conductive layers 630A, 630B and the adhesion between the first conductive layers 610A, 610B and the second conductive layers 630A, 630B, the second conductive layers 630A, 630B on the insulating layer 620 are peeled off from the surface of the substrate W. As a result, as shown in Fig. 8B , the second conductive layers 630A, 630B remain on the first conductive layers 610A, 610B, and a pattern of the second conductive layers 630A, 630B is formed.

[0060] [Pattern formation method using pattern formation apparatus according to second embodiment] An example of a pattern formation method using the pattern formation apparatus 200a according to the second embodiment will be described with reference to Fig. 9. Fig. 9 is a flowchart showing an example of a pattern formation method using the pattern formation apparatus 200a according to the second embodiment. The pattern formation method of Fig. 9 is controlled by a control unit 290.

[0061] In the pattern forming method of FIG. 9, in step S11, the substrate W on which the patterns of the first conductive layer and the insulating layer have been formed is transported to the film forming apparatus 300 and prepared.

[0062] In step S12, a second conductive layer is formed on the surface of the substrate W.

[0063] In step S13, the substrate W on which the second conductive layer has been formed is transported to the pattern forming apparatus 200a.

[0064] In step S14, an ionic liquid is supplied to the processing bath 212, and the surface of the substrate W is immersed in the ionic liquid.

[0065] In step S15, a probe at the tip of the electrode 216 connected to the power supply device 215 is brought into contact with the metal plate 213 arranged on the bottom surface of the treatment tank 212a. The other electrode 217 connected to the power supply device 215 is immersed in the ionic liquid. The back surface and front surface of the substrate W are electrically connected. Therefore, a current is passed from the power supply device 215 through the ionic liquid I from the back surface of the substrate W in contact with the metal plate 213 to the first conductive layer.

[0066] In step S16, due to the difference in adhesion between the insulating layer and the second conductive layer and the adhesion between the first conductive layer and the second conductive layer, the second conductive layer on the insulating layer is peeled off from the surface of the substrate W, and a pattern of the second conductive layer is formed on the first conductive layer.

[0067] 10A to 10D show an example of application of the pattern formation method according to the second embodiment to a process. FIG. 10B shows a cross section taken along the line CC of FIG. 10A. As shown in FIGS. 10A and 10B, the substrate W to be prepared has a first layer having a pattern of a first conductive layer 610 and an insulating layer 620, and a second layer 660 formed on the first layer. The second layer 660 is formed of an insulating layer, and has a hole 661 formed therethrough that penetrates to the first conductive layer 610 of the first layer. The insulating layer 620 and the second layer 660 are, for example, a low-k film. The first conductive layer 610 is a metal film.

[0068] In steps S11 and S12, the second conductive layer 670 is formed on the surface of the substrate W prepared in the film forming apparatus 300. As a result, the second conductive layer 670 is formed in the holes 661 and on the second layer 660, as shown in FIG.

[0069] In steps S13 to S15, the surface of the substrate W transported to the pattern forming apparatus 200a is immersed in an ionic liquid, and a current is passed from the power supply 215 through the ionic liquid to the first conductive layer 610. As a result, in step S16, due to the difference in adhesion between the second layer 660 and the second conductive layer 670 and the adhesion between the first conductive layer 610 and the second conductive layer 670, the second conductive layer 670 on the second layer 660 is peeled off from the surface of the substrate W. As a result, as shown in FIG. 10D , the second conductive layer 670 remains only in and immediately above the holes 661 on the first conductive layer 610, and a pattern of the second conductive layer 670 is formed.

[0070] As described above, according to the pattern formation methods and pattern formation devices of the first and second embodiments, on a substrate on which patterns of a first conductive layer and an insulating layer have been formed, it is possible to form a pattern of a second conductive layer on the first conductive layer by utilizing the difference in adhesion between the layers.

[0071] [Others] (Ionic Liquid) The ionic liquid is selected from a number of combinations of cations and anions, and is liquid at room temperature. Since it is believed that the cation mainly acts to peel off the second conductive layer, for example, the following combinations of anions and cations may be used as the ionic liquid. Anion: pyrrolidinium salt such as 1-Ethyl-1-methylpyrrolidinium, imidazolium salt such as 1-Ethyl-3-methylimidazolium Cation: Al ２ Cl ７ , AlCl ４ , B.F. ４ , P.F. ６

[0072] (Voltage Value / Current Density) The current density and / or voltage value applied to the first conductive layer from the power supply device via the ionic liquid is set to a value in the range of 500 mA / cm ２ The current density and / or voltage value applied to the first conductive layer from the power supply device via the ionic liquid may be at least one of a current density of 50 mA / cm or less, or a voltage value of 15 V or less. If at least one of the current density and voltage value controlled by the power supply device does not satisfy these conditions, the ionic liquid may be broken or may have adverse effects on devices such as metal wiring fabricated on the substrate W. More preferably, the current density and / or voltage value applied from the power supply device via the ionic liquid to the first conductive layer may be at least one of a current density of 50 mA / cm or less. ２ The voltage value may be at least one of 5 V or less, or 5 V or less. This can further reduce the possibility of destruction of the ionic liquid and adverse effects on devices on the substrate W.

[0073] (Other Process Application Examples) Other process application examples will be described with reference to Figures 11A to 11D. Figures 11A to 11D are diagrams showing other process application examples. In the manufacturing process, a probe needle is applied to a wiring for inspection. Therefore, physical contact of the probe needle with the wiring may damage the wiring.

[0074] Therefore, as shown in FIG. 11B, a dummy pad 105 is formed on a pattern of an insulating layer 101 such as a low-k film and a first conductive layer 102 of a wiring layer via a second conductive layer 103. As in the case of forming another film 104 on the second conductive layer 103 shown in FIG. 2A, the dummy pad 105 can be formed by utilizing the difference in adhesion between layers by forming a pattern on a substrate using an ionic liquid, as shown in FIG. 11C. That is, only the second conductive layer 103 and dummy pad 105 on the first conductive layer 102, which has good adhesion, are selectively left, and the second conductive layer 103 and dummy pad 105 on the insulating layer 101, which has poor adhesion, are peeled off at once, and the second conductive layer 103 and dummy pad 105 are formed on the pattern of the first conductive layer 102.

[0075] The second conductive layer 103 may be made of any of precious metals such as gold, silver, platinum, palladium, rhodium, iridium, ruthenium, and osmium. The first conductive layer 102 may be made of any of wiring materials such as Cu, W, TiN, Al, and Co.

[0076] 11C , the probe needle P is placed on the dummy pad 105 during inspection in the manufacturing process, and therefore the probe needle does not physically come into contact with the first conductive layer 102. Therefore, the inspection can be performed without damaging the first conductive layer 102.

[0077] 11D, the damaged dummy pads 105 are removed later. In this case, the dummy pads 105 can be removed by CMP, wet etching, or the like. The removal of the dummy pads 105 does not involve the method of forming a pattern on a substrate using an ionic liquid.

[0078] The pattern formation method and pattern formation apparatus according to the presently disclosed embodiments should be considered to be illustrative in all respects and not restrictive. The embodiments can be modified and improved in various ways without departing from the scope and spirit of the appended claims. The features described in the above embodiments can be configured in other ways within a consistent range, and can be combined within a consistent range.

[0079] This international application claims priority based on Japanese Patent Application No. 2023-166462, filed on September 27, 2023, the entire contents of which are incorporated herein by reference.

[0080] 200 Pattern forming device 210 Chamber 212 Processing tank 215 Power supply unit 220 Liquid supply unit 230 Liquid circulation unit 290 Control unit

Claims

1. A pattern forming method comprising: preparing a substrate having a second conductive layer on a surface of the substrate on which a pattern of a first conductive layer and an insulating layer is formed; supplying an ionic liquid to the surface of the substrate; and forming a pattern of the second conductive layer on the first conductive layer by passing an electric current through the first conductive layer to which the ionic liquid has been supplied.

2. The pattern forming method according to claim 1, wherein forming the pattern comprises peeling off the second conductive layer on the insulating layer to form a pattern of the second conductive layer.

3. The pattern forming method according to claim 1, wherein the second conductive layer is any one of a noble metal, tungsten, molybdenum, and copper.

4. The pattern forming method according to claim 3, wherein the second conductive layer is a noble metal.

5. The pattern formation method according to claim 4, wherein the noble metal is any one of gold, silver, platinum, palladium, rhodium, iridium, ruthenium and osmium.

6. The pattern forming method according to any one of claims 1 to 4, further comprising depositing the second conductive layer on the surface of the substrate before preparing the substrate.

7. The pattern forming method according to claim 6, further comprising depositing another film on the second conductive layer after depositing the second conductive layer and before preparing the substrate.

8. The pattern formation method according to any one of claims 1 to 4, wherein when the rear surface and the front surface of the substrate are electrically connected, passing a current through the first conductive layer comprises contacting a probe connected to a power supply unit with the rear surface and passing a current through the first conductive layer via the ionic liquid.

9. A pattern formation method according to any one of claims 1 to 4, further comprising monitoring the position of the first conductive layer, and passing a current through the first conductive layer by contacting a probe connected to a power supply with the second conductive layer immediately above the monitored first conductive layer and passing a current through the first conductive layer via the ionic liquid.

10. The current density and / or voltage value applied to the first conductive layer is 500 mA / cm ２ The pattern formation method according to any one of claims 1 to 4, wherein the voltage value is at least either 1 V or less, or 15 V or less.

11. The current density and / or voltage value applied to the first conductive layer is 50 mA / cm ２ The pattern formation method according to claim 10 , wherein the voltage value is at least either one of 5 V or less or 10 V or less.

12. A pattern forming apparatus comprising: a chamber; a processing tank disposed within the chamber; a power supply unit; and a control unit, wherein the control unit controls the following: preparing a substrate in the processing tank, the substrate having a second conductive layer on a surface of the substrate on which a pattern of a first conductive layer and an insulating layer is formed; supplying an ionic liquid to the surface of the substrate in the processing tank; and forming a pattern of the second conductive layer on the first conductive layer by passing a current from the power supply unit to the first conductive layer to which the ionic liquid has been supplied.

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