Substrate processing method and substrate processing apparatus

Abstract

To provide a substrate processing method and a substrate processing apparatus, capable of improving accuracy of an exposure performed to a front surface of a substrate for forming a pattern.SOLUTION: A semiconductor wafer W includes: a front surface Wf as a main surface, exposed for forming a pattern; and a back surface Wb as a main surface that is an opposite side of the front surface. Before the exposure for forming the pattern to the front surface of the semiconductor wafer, flatness processing for flatting the back surface is performed. The flatness processing contains: a convex part removing step of removing a convex part 91 existed in the back surface of the semiconductor wafer by chemical polishing; and a concave embedding step of embedding a flowability flexible material 96 into a concave part 92 existed on the back surface of the semiconductor wafer after the convex part removing step. After the post-processing to the front surface of the semiconductor wafer W, it is preferable to remove a sacrificial film 97 formed of the flexible material 96.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a substrate processing method and a substrate processing apparatus. Substrates to be processed include, for example, semiconductor wafers, substrates for flat panel displays (FPDs) such as liquid crystal display devices and organic EL (Electroluminescence) display devices, photomask substrates, ceramic substrates, solar cell substrates, and the like.

Background Art

[0002] In the manufacturing process of semiconductor devices, a plurality of photolithography processes are performed on a substrate (specifically, a semiconductor wafer). The photolithography process includes a process of forming a resist film on the substrate, a process of exposing the resist film to a predetermined pattern by an exposure apparatus (pattern exposure), and a process of developing the exposed resist film. For example, in the formation of a multilayer wiring structure, the accuracy of alignment of the exposure area, that is, the overlay accuracy, between a certain lithography process and a subsequent lithography process is important. When forming fine wirings, particularly high overlay accuracy is required.

[0003] An exposure apparatus includes, for example, a substrate stage for holding a substrate, a reticle stage for holding a reticle on which a circuit pattern is drawn, and a projection optical system for performing exposure (for example, shot exposure) on the substrate on the substrate stage through the reticle. The substrate stage adsorbs and holds the back surface of the substrate. In a projection exposure apparatus, the back surface of the substrate is held by a vacuum chuck. In an EUV (Extreme Ultraviolet) exposure apparatus, since exposure is performed in a vacuum state, the back surface of the substrate is held by an electrostatic chuck. The electrostatic chuck device includes a flat adsorption stage and a large number of fine convex portions distributed on the adsorption surface of the adsorption stage, and is configured to electrostatically adsorb and hold the substrate in a state where the large number of convex portions contact the back surface of the substrate. ​​To improve overlay accuracy, it is crucial that the substrate is positioned precisely on the adsorption stage and that the area of ​​exposure shot in the previous photolithography process is accurately aligned with the area of ​​exposure shot in the subsequent photolithography process.

[0005] Patent Document 1 discloses a method in which the back surface of a substrate is polished before pattern exposure to roughen the back surface, thereby reducing the contact area between the back surface of the substrate and the suction stage during exposure, and enabling the back surface of the substrate to slide on the suction stage. It is explained that this straightens the substrate along the surface of the suction stage, eliminating its distortion, and thereby improving the overlay accuracy. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2017-69271 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, the roughening treatment of the back surface reduces the flatness of the back surface of the substrate, which may cause the surface of the substrate to fall outside the depth of focus range (focus error that does not hinder pattern formation) of the exposure apparatus. In addition, depending on the positional relationship between the irregularities formed on the back surface of the substrate by the roughening treatment and the protrusions provided on the suction stage, the distortion of the substrate may not be eliminated, and the effect intended in Patent Document 1 may not be achieved.

[0008] Therefore, one embodiment of this invention provides a substrate processing method and a substrate processing apparatus that can improve the accuracy of exposure performed on the surface of a substrate to form a pattern. [Means for solving the problem]

[0009] One embodiment of this invention provides a substrate processing method for processing a substrate having a surface which is a main surface to be exposed for pattern formation and a back surface which is a main surface opposite to the surface. This substrate processing method includes a planarization process to flatten the back surface before exposure to form a pattern on the surface. The planarization process includes a protrusion removal step of removing protrusions present on the back surface of the substrate by chemical polishing, and a recess filling step of filling recesses present on the back surface of the substrate with a fluid plastic material after the protrusion removal step.

[0010] According to this method, the back surface of the substrate is flattened by removing protrusions through chemical polishing and filling recesses with a fluid, plastic material. By removing protrusions not only through physical polishing but also through chemical polishing, damage to the back surface of the substrate can be suppressed while removing the protrusions. Then, by filling the recesses on the back surface of the substrate from which the protrusions have been removed with a fluid, plastic material, the back surface of the substrate can be flattened with high precision. Therefore, when exposure (pattern exposure) is performed to form a pattern on the surface of the substrate after the back surface has been flattened, the substrate can have a high degree of flatness. As a result, each part of the substrate surface is more likely to fall within the depth of field range of the exposure apparatus. In other words, the positional accuracy of the substrate surface during exposure, especially the positional accuracy in the direction of the depth of field of the exposure apparatus (specifically, the direction perpendicular to the main surface of the substrate), is improved. This improves the quality of pattern exposure.

[0011] Furthermore, when the substrate is adsorbed and held on the adsorption stage during pattern exposure, adsorption defects can be suppressed. In addition, the plastic material on the back of the substrate deforms to absorb at least a portion of any foreign matter present on the adsorption stage where the substrate is adsorbed. This further suppresses adsorption defects. Moreover, since the plastic material adsorbs foreign matter, when the substrate is discharged from the adsorption stage, the foreign matter is carried away along with the substrate. As a result, the adsorption stage can be kept clean, reducing the frequency of maintenance on the adsorption stage, and consequently increasing the operating rate of the equipment using the adsorption stage.

[0012] Furthermore, the plastic material relieves the stress exerted on the substrate by the adsorption stage, and also relieves the stress caused by any foreign matter present on the adsorption stage. This enables high-quality substrate processing while suppressing adverse effects on the characteristics of the devices formed on the substrate.

[0013] In one embodiment, the protrusion removal step includes a chemical supply step of supplying a chemical solution to the back surface of the substrate, and a scrubbing step of scrubbing the back surface of the substrate to which the chemical solution has been supplied by the chemical supply step with an abrasive brush. This method allows for the removal of protrusions on the back surface of the substrate while suppressing damage to the back surface of the substrate by using a combination of chemical action by the chemical solution and physical action by the abrasive brush.

[0014] The chemical solution preferably contains one or more selected from the group consisting of hydrofluoric acid, hydrofluoric acid-hydrogen peroxide solution, ozone-containing hydrofluoric acid solution, ammonia-hydrogen peroxide solution, ozone-containing sulfuric acid solution, hydrochloric acid-hydrogen peroxide solution, ozonated water, sulfuric acid-hydrogen peroxide solution (SPM), and hydrogen peroxide solution. By selecting an appropriate chemical solution according to the material on the back surface of the substrate, protrusions can be removed while suppressing damage to the back surface of the substrate.

[0015] Preferably, the polishing brush has a polishing surface made of one or more materials selected from the group consisting of polyvinyl alcohol, silicon carbide, and diamond. By selecting a polishing brush made of an appropriate material depending on the material of the back surface of the substrate, it is possible to remove protrusions on the back surface of the substrate while suppressing damage to the back surface of the substrate. More preferably, the polishing brush has a polishing surface in which abrasive grains are contained in the brush pad binder. In this case, it is preferable that the abrasive grains include one or more of cerium (Ce), silicon carbide (SiC), and diamond (C). Furthermore, it is preferable that the brush pad binder is made of PVA (polyvinyl alcohol), PP (polypropylene), PTFE (polytetrafluoroethylene, fluororesin), etc. The polishing surface of the polishing brush can be formed according to the material of the back surface of the substrate and the chemical solution used.

[0016] The aforementioned plastic material preferably includes either a resin material or a silicon-based material, or a mixture thereof. Such a plastic material can exhibit a fluid state and has appropriate flexibility (elasticity) in a solidified state. This suppresses stress concentration on the substrate when it is adsorbed by the adsorption stage. In other words, it is possible to achieve high flatness of the substrate on the adsorption stage while suppressing stress concentration.

[0017] The resin material includes, for example, polyimide. The silicon-based material includes, for example, a methyl-based silicon coating material. Since these resin materials and silicon-based materials have one or more of the properties of oil repellency, water repellency, and antifouling, they can be expected to have the effect of protecting the back surface of the substrate.

[0018] The aforementioned plastic material preferably includes an organosilicon material. By using an organosilicon material (silicone) as the plastic material, it is expected that when the plastic material on the back surface of the substrate comes into contact with the adsorption stage, it will have the effect of removing foreign matter (especially particles) present on the adsorption stage. As a result, a special cleaning process for cleaning the adsorption stage can be eliminated or reduced in frequency. Therefore, the operating rate of the apparatus using the adsorption stage can be increased.

[0019] In one embodiment, the recess-filling step includes a coating step of applying a fluid plastic material to the back surface of the substrate, and an excess material removal step after the coating step of removing excess plastic material by scrubbing the back surface of the substrate with a brush. By removing the excess plastic material with a brush scrub, the flatness of the back surface of the substrate in which the plastic material is embedded in the recesses can be increased.

[0020] In one embodiment, a solidification step is further included after the coating step and before the excess material removal step, in which the plastic material is solidified. This ensures that the recesses on the back surface of the substrate are filled with the plastic material.

[0021] For example, the solidification step preferably includes at least one of a bake treatment, in which the plastic material is heated to 100°C to 400°C, and an ultraviolet treatment, in which the plastic material is irradiated with ultraviolet light. When using a heat-curing type plastic material, a bake treatment is preferable. When using an ultraviolet-curing type plastic material, an ultraviolet treatment is preferable.

[0022] In one embodiment, the substrate processing method further includes a surface processing step for processing the surface of the substrate after the recess filling step, and a removal step for removing the plastic material from the back surface of the substrate after the surface processing step.

[0023] According to this method, since the plastic material is removed after the surface treatment step, the substrate treatment can be completed with no plastic material adhering to the back surface. Therefore, the influence of the plastic material on the substrate can be avoided.

[0024] Preferably, the removal step includes a step of supplying an alkaline chemical solution or a chemical solution containing an oxidant to the back surface of the substrate to dissolve the plastic material.

[0025] When the plastic material is a silicon-rich organosilicon material, the plastic material can be dissolved and removed by an alkaline chemical solution. One specific example of the silicon-rich organosilicon material is an ultraviolet curable liquid silicone rubber, and more specifically, it may be PDMS (polydimethylsiloxane). Specific examples of the alkaline chemical solution include TMAH (tetramethylammonium hydroxide) and SC1 (ammonia hydrogen peroxide mixture).

[0026] When the plastic material is an organic-rich organosilicon material, the plastic material can be dissolved and removed by a chemical solution containing an oxidant. One specific example of the organic-rich organosilicon material is a polyimide polymer. Specific examples of the chemical solution containing an oxidant include ozone water, an ozone-containing hydrofluoric acid solution, a sulfuric acid hydrogen peroxide mixture (SPM: Sulfuric Acid Hydrogen Peroxide Mixture), and an ozone-containing sulfuric acid solution.

[0027] In one embodiment, the surface treatment step includes a step of adsorbing and holding the back surface of the substrate on an adsorption stage, and a step of pattern-exposing the surface of the substrate held on the adsorption stage.

[0028] The back surface of the substrate adsorbed on the adsorption stage is a surface that has undergone planarization treatment and is a flat surface with excellent flatness. Therefore, since the substrate adsorbed on the adsorption stage has excellent flatness, high-quality pattern exposure is possible.

[0029] Furthermore, since a plastic material is applied to the back surface of the substrate (especially within the recesses), the stress when the substrate is adsorbed onto the adsorption stage can be absorbed by the plastic material. In addition, foreign matter on the adsorption stage can be adsorbed onto the plastic material, and when the substrate is discharged, the foreign matter can be removed at the same time, thus keeping the adsorption stage clean.

[0030] In one embodiment, the substrate processing method further includes a step of adsorbing and holding the back surface of the substrate on an adsorption stage and processing the surface of the substrate before the planarization process. Even if irregularities occur on the back surface of the substrate due to adsorption of the back surface of the substrate on the adsorption stage, these irregularities can be improved by the planarization process, and the back surface of the substrate will have excellent flatness during pattern exposure. This enables high-quality pattern exposure.

[0031] One embodiment of this invention provides a substrate processing apparatus that processes a substrate having a surface which is the main surface on which a pattern is formed and a back surface which is the main surface opposite to the surface, before exposure for forming the pattern. This substrate processing apparatus includes a chemical polishing unit that supplies a chemical solution to the back surface of the substrate and scrubs the back surface with a polishing brush, and a coating unit that supplies a coating solution containing a fluid plastic material to the back surface of the substrate and forms a coating film containing the plastic material.

[0032] In one embodiment, the substrate processing apparatus further includes a transport robot that transports the substrate processed by the chemical polishing unit to the coating unit.

[0033] In one embodiment, the substrate processing apparatus further includes a solidification unit that processes a substrate on which a coating film of the plastic material is formed on the back surface and solidifies the coating film.

[0034] The solidification unit preferably includes at least one of a heating unit for heating the substrate and an ultraviolet treatment unit for irradiating the substrate with ultraviolet light.

[0035] The aforementioned chemical solution preferably contains one or more selected from the group consisting of hydrofluoric acid, hydrofluoric acid hydrogen peroxide solution, sulfuric acid hydrogen peroxide solution (SPM), ozone-containing hydrofluoric acid solution, ammonia hydrogen peroxide solution, ozone-containing sulfuric acid solution, hydrochloric acid hydrogen peroxide solution, ozonated water, and hydrogen peroxide solution.

[0036] The polishing brush preferably has one or more materials selected from the group consisting of polyvinyl alcohol, silicon carbide, and diamond on its polishing surface. More preferably, the polishing brush has a polishing surface in which abrasive grains are contained in the brush pad binder. In this case, the abrasive grains preferably contain one or more of cerium (Ce), silicon carbide (SiC), and diamond (C). Furthermore, the brush pad binder is preferably composed of PVA (polyvinyl alcohol), PP (polypropylene), PTFE (polytetrafluoroethylene, fluororesin), etc.

[0037] The aforementioned plastic material preferably includes either a resin material or a silicon-based material, or a mixture thereof.

[0038] The aforementioned plastic material preferably includes an organosilicon material. [Brief explanation of the drawing]

[0039] [Figure 1] Figure 1 is a diagram illustrating the challenges associated with the use of an electrostatic chuck device. [Figure 2] Figure 2 shows an example of a process for improving the surface irregularities on the back of a semiconductor wafer W. [Figure 3] Figure 3 shows another process example. [Figure 4] Figure 4 shows a more specific example of the process. [Figure 5] Figure 5 shows an example of a substrate processing system that can be used to perform the above process. [Figure 6]Figure 6 is a schematic plan view illustrating an example of the configuration of a substrate cleaning apparatus that constitutes the substrate processing system. [Figure 7] Figure 7 shows an example of the configuration of a chemical cleaning unit provided in the substrate cleaning apparatus. [Figure 8] Figure 8 shows an example of the configuration of a coating unit provided in the substrate cleaning apparatus. [Figure 9] Figure 9 shows an example of the configuration of a solidification unit provided in the substrate cleaning apparatus. [Figure 10] Figure 10 shows another example of the configuration of the solidification unit provided in the substrate cleaning apparatus. [Modes for carrying out the invention]

[0040] Hereinafter, embodiments of this invention will be described in detail with reference to the accompanying drawings.

[0041] Figure 1 illustrates the challenges associated with the use of an electrostatic chuck device. In the manufacturing process of semiconductor devices, an electrostatic chuck device 80 is used to hold a semiconductor wafer W, which is an example of a substrate, by adsorbing its back surface Wb. More specifically, the electrostatic chuck device 80 is used to hold the semiconductor wafer W to be processed in processes such as photolithography, etching, and thin film formation.

[0042] The photolithography process includes the steps of forming a resist film on the surface Wf of a semiconductor wafer W, exposing the resist film, and developing the resist film after exposure. For example, an electrostatic chuck device 80 is provided in the exposure apparatus for exposing the resist film, and the semiconductor wafer W to be exposed is held by the electrostatic chuck device 80 by adsorption of its back surface Wb.

[0043] The etching process may be a dry etching process, such as reactive ion etching. The semiconductor wafer W is held by an electrostatic chuck device 80 provided in the etching apparatus, with its back surface Wb adsorbed onto it, and etching is performed using a resist film or the like formed on the front surface Wf of the semiconductor wafer W as a mask.

[0044] The thin-film formation process involves forming a thin film using methods such as PVD (Physical Vapor Deposition) or CVD (Chemical Vapor Deposition). A semiconductor wafer W is held by an electrostatic chuck device 80 attached to the film formation apparatus, with its back surface Wb adsorbed onto it. In this state, a thin film is formed on the front surface Wf of the semiconductor wafer W.

[0045] The electrostatic chuck device 80 includes a flat suction stage 81 and a number of protrusions 83 distributed on the suction surface 82 of the suction stage 81. The back surface Wb of the semiconductor wafer W is in contact with the protrusions 83 and is attracted toward the suction stage 81 by electrostatic force. Ideally, this results in the semiconductor wafer W exhibiting a flat shape along the suction surface 82 of the suction stage 81.

[0046] When the semiconductor wafer W is sucked in, the back surface Wb is pressed against the protrusion 83 of the suction stage 81, and when the suction is released, it is released from the protrusion 83 of the suction stage 81. At this time, localized friction occurs between the protrusion 83 and the back surface Wb of the semiconductor wafer W. As a result, material on the back surface Wb of the semiconductor wafer W falls off, creating fine irregularities on the back surface Wb of the semiconductor wafer W.

[0047] When a semiconductor wafer W having such irregularities on its back surface Wb is held in another electrostatic chuck device 80, the flatness of the semiconductor wafer W when it is adsorbed onto the adsorption stage 81 of the electrostatic chuck device 80 is affected by the irregularities on the back surface Wb. This can, for example, cause focus misalignment during exposure, potentially leading to exposure failure. Specifically, if the irregularities on the surface Wf of the semiconductor wafer W exceed the depth of focus range of the exposure device, exposure failure occurs. This results in so-called depth of focus (DOF) hot spots in the resist pattern.

[0048] On the other hand, the material on the back surface Wb of the semiconductor wafer W is desorbed drop This generates particles P, which remain on the adsorption surface 82. These particles P can cause adsorption errors when the next semiconductor wafer W is held on the adsorption stage 81 of the electrostatic chuck device 80. Even if an adsorption error does not occur, the particles P affect the flatness of the adsorbed semiconductor wafer W, which can lead to, for example, focus misalignment during exposure and cause exposure failures. Specifically, if the surface irregularities Wf of the semiconductor wafer W exceed the depth of focus range of the exposure device, exposure failures occur. As a result, so-called depth of focus hot spots are created in the resist pattern.

[0049] The material of the back surface Wb of the semiconductor wafer W may be bare silicon material (i.e., silicon), or it may be the material of a thin film formed on the back surface Wb (for example, a protective film such as a silicon nitride film).

[0050] Figure 2 shows an example of a process for improving the unevenness of the back surface Wb of a semiconductor wafer W. As mentioned above, unevenness occurs on the back surface Wb of a semiconductor wafer W after a surface treatment process (surface process 1, such as photolithography, etching, and film deposition) is performed on the surface Wf of the semiconductor wafer W while holding it with an electrostatic chuck device 80. Chemical polishing is performed on the back surface Wb of the semiconductor wafer W in which unevenness has occurred, by supplying a chemical solution and polishing with a polishing brush (back surface chemical polishing process). This removes the protrusions 91 on the back surface Wb of the semiconductor wafer W (protrusion removal process). After the protrusions 91 have been removed, a fluid plastic material 96 is filled into the recesses 92 remaining on the back surface Wb of the semiconductor wafer W to form a sacrificial film 97 (sacrificial film coating process, recess filling process). This makes the back surface Wb of the semiconductor wafer W flat (planarization process). When the semiconductor wafer W in this state is held in the electrostatic chuck device 80 (see Figure 1) during the next process (for example, the exposure process), it exhibits excellent flatness. Therefore, for example, the exposure process can be performed with high precision, and a highly accurate pattern can be formed on the surface Wf of the semiconductor wafer W.

[0051] On the other hand, the sacrificial film 97, made of a fluid plastic material 96, absorbs and relieves stress from the protrusions 83 (see Figure 1) of the adsorption surface 82 (see Figure 1) of the electrostatic chuck device 80 when it comes into contact with the adsorption surface 82. Furthermore, the sacrificial film 97 can at least partially incorporate particles P (see Figure 1) present on the adsorption surface 82 (especially the surface of the protrusions 83) into the film. This allows for the absorption of stress from the particles P and suppresses adsorption failures. Moreover, the particles P incorporated into the sacrificial film 97 are carried away together with the semiconductor wafer W when it is dispensed, thus cleaning the adsorption surface 82. Therefore, the adsorption surface 82 of the electrostatic chuck device 80 is kept clean without the need for any special cleaning treatment. This further improves the flatness of the semiconductor wafer W when it is adsorbed onto the adsorption stage 81 of the electrostatic chuck device 80.

[0052] Figure 3 shows another process example. In this example, a sacrificial film 97 is formed on the back surface Wb of a semiconductor wafer W through a process similar to that in Figure 2 (surface process 1: back surface chemical polishing and sacrificial film coating). Further surface treatment steps (surface process 2: photolithography, etching, film deposition, etc.) are performed on the surface Wf of the semiconductor wafer W. During this surface process 2, the back surface Wb of the semiconductor wafer W is held by an electrostatic chuck device 80 (see Figure 1). As a result, irregularities are formed on the back surface Wb of the semiconductor wafer W where the sacrificial film 97 is formed, due to contact with the protrusions 83 of the adsorption surface 82 of the electrostatic chuck device 80. Specifically, recesses 102 are formed in the sacrificial film 97, and protrusions 101 are formed around its periphery. A sacrificial film removal process (sacrificial film selective removal process) is then performed on the semiconductor wafer W to remove the sacrificial film 97 from the back surface Wb. As a result, the back surface Wb of the semiconductor wafer W without the sacrificial film 97 is exposed. Therefore, the processing of the semiconductor wafer W can be completed without leaving any influence of the sacrificial film 97.

[0053] Figure 4 shows a more specific example of the process. After cleaning the semiconductor wafer W to be processed, a protective film 100 is formed on the back surface Wb of the semiconductor wafer W. The protective film 100 may also be formed on the front surface Wf of the semiconductor wafer W, and Figure 4 shows an example in which the protective film 100 is formed on both the front surface Wf and the back surface Wb of the semiconductor wafer W. The protective film 100 is typically an insulating film, and more specifically, it may be a silicon nitride film.

[0054] After the protective film 100 is formed, a first surface process (surface process 1; first surface treatment step) is performed on the surface Wf of the semiconductor wafer W. The first surface process includes, for example, one or more of a photolithography step, an etching step, and a film formation step. In at least one of these steps, the back surface Wb of the semiconductor wafer W is adsorbed and held by an electrostatic chuck device 80 (see Figure 1). Therefore, the back surface Wb of the semiconductor wafer W after the first surface process has irregularities formed due to contact with a number of protrusions 83 (see Figure 1) provided on the adsorption surface 82 of the adsorption stage 81 of the electrostatic chuck device 80. More specifically, when the protective film 100 on the back surface Wb of the semiconductor wafer W comes into contact with the protrusions 83 of the electrostatic chuck device 80 and localized friction occurs, the material of the protective film 100 is scraped off. A recess 92 is formed in the scraped-off portion, and a protrusion 91 is formed around the periphery of the recess 92. When the material detaches from the protective film 100, the detached material becomes a particle P (see Figure 1).

[0055] After the first surface process, chemical polishing (backside chemical polishing process) is performed on the back surface Wb of the semiconductor wafer W. This removes the protrusions 91 that have formed on the back surface Wb of the semiconductor wafer W. Chemical polishing, which uses both chemical and physical actions, can remove the protrusions 91 while suppressing damage to the back surface Wb of the semiconductor wafer W (protrusion removal process). In other words, chemical polishing does not damage the back surface Wb of the semiconductor wafer W (the surface of the protective film 100 in this example), so it removes the protrusions 91 while suppressing the formation of new depressions on the back surface Wb.

[0056] Examples of chemical polishing solutions include hydrofluoric acid (HF), hydrofluoric acid-hydrogen peroxide mixture (FPM), ozone-containing hydrofluoric acid solution (FOM; hydrofluoric acid-ozone water mixture), SC1 (ammonia-hydrogen peroxide mixture), and ozone-containing sulfuric acid solution (SOM; sulfuric acid-ozone water mixture). ,salt Acid and hydrogen peroxide mixture liquid,It may be one or more of the following: ozonated water (O3), sulfuric acid hydrogen peroxide mixture (SPM), hydrogen peroxide (H2O2), etc.

[0057] Polishing brushes used for chemical polishing may have one or more of the following materials on their polishing surface: polyvinyl alcohol (PVA), silicon carbide (SiC), diamond, etc. More specifically, it is preferable that the polishing brush has a polishing surface in which abrasive grains are contained in the brush pad binder. In this case, it is preferable that the abrasive grains include one or more of the following materials: cerium (Ce), silicon carbide (SiC), and diamond (C). Furthermore, it is preferable that the brush pad binder is composed of PVA (polyvinyl alcohol), PP (polypropylene), PTFE (polytetrafluoroethylene, fluororesin), etc.

[0058] After chemical polishing, the semiconductor wafer W is cleaned, and any substances that have come off the semiconductor wafer W due to dissolution by the chemical solution or shear force from polishing are washed away.

[0059] After chemical polishing of the back surface Wb of the semiconductor wafer W and subsequent necessary cleaning are completed, a sacrificial film coating is applied to the back surface Wb of the semiconductor wafer W. Specifically, a fluid plastic material 96 is embedded in the recesses 92 that have formed on the back surface Wb of the semiconductor wafer W (more specifically, the exposed portion of the protective film 100) (recess embedding process).

[0060] Sacrificial film coating includes, for example, a coating step of applying a fluid plastic material 96 (material for the sacrificial film 97) to the back surface Wb of a semiconductor wafer W, and an excess material removal step of removing excess plastic material 96 from the back surface Wb of the semiconductor wafer W. The coating step embeds the plastic material 96 in the recesses 92 of the back surface Wb of the semiconductor wafer W, and also deposits plastic material 96 in the flat areas 93 outside the recesses 92, thereby forming a coated film. After the coating step, it is preferable to perform a solidification step to solidify the coated film formed on the back surface Wb of the semiconductor wafer W, and it is preferable to perform the excess material removal step after the solidification step.

[0061] The excess material removal step removes the plastic material 96 deposited on the flat portion 93 outside the recess 92. However, it is not necessary to remove all of the plastic material 96 deposited on the flat portion 93; if the back surface Wb of the semiconductor wafer W becomes flat as a whole, the plastic material 96 may remain on the flat portion 93. The excess material removal step may also be performed by chemical polishing. Chemical polishing is preferably performed under conditions where the selective removal ratio of the plastic material 96 to the material of the protective film 100 is large, thereby selectively removing the plastic material 96 while suppressing damage to the protective film 100, and flattening the back surface Wb of the semiconductor wafer W.

[0062] After the coating process and prior to the excess material removal process, it is preferable to perform an edge rinsing treatment to clean the plastic material 96 adhering to the edges (especially the peripheral edges) of the semiconductor wafer W.

[0063] The solidification step may be a step of cooling and solidifying the coated film, or a step of heating and solidifying it (baking step). The solidification step is preferably performed after the edge rinsing step described above. For example, the baking step may be a step of heating the plastic material 96 to 100°C to 400°C. After the baking step, it is preferable to perform a cooling step to cool the semiconductor wafer W to, for example, room temperature. Room temperature is the ambient temperature of the space where the processing apparatus for processing the semiconductor wafer W is located, and more specifically, the temperature inside the cleanroom of a semiconductor device production plant. A typical room temperature range is generally 0°C to 30°C, more specifically, for example, 20 to 30°C (for example, 23°C).

[0064] Furthermore, the solidification step may be an ultraviolet irradiation step in which the coated film is irradiated with ultraviolet light. The ultraviolet treatment may be performed in place of or in addition to the baking step. When using a plastic material 96 with a composition that hardens when exposed to ultraviolet light, it is preferable to perform the ultraviolet irradiation step.

[0065] The fluid plastic material 96 used in the coating process includes either a resin material or a silicon-based material, or a mixture thereof. The resin material includes, for example, polyimide. The silicon-based material includes, for example, a methyl-based silicon coating material. Preferably, the plastic material 96 has one or more of the following properties: oil repellency, water repellency, and antifouling. Both polyimide and methyl-based silicon coating materials are materials that have oil repellency, water repellency, and antifouling properties. More specifically, the plastic material 96 may be a cleaning material used on the cleaning surface of a chuck cleaning wafer that cleans the chuck surface of the electrostatic chuck device 80. A typical cleaning material includes at least one of polyimide and a methyl-based silicon coating material. Another typical cleaning material is an organosilicon material. By using these materials as the plastic material 96, when the sacrificial film 97 comes into contact with the adsorption surface 82 of the electrostatic chuck device 80, it adsorbs foreign matter (mainly particles P) on the adsorption surface 82.

[0066] In the chemical polishing process for removing excess material, if the plastic material 96 is an organic-rich organosilicon material, it is preferable to use a chemical solution containing an oxidizing agent such as ozone (oxidizing agent-containing chemical solution). If the plastic material 96 is a silicon-rich organosilicon material, it is preferable to use an alkaline chemical solution such as TMAH (tetramethylammonium hydroxide) or SC1 (ammonia hydrogen peroxide solution). In either case, the organosilicon material, which is the plastic material 96, can be dissolved by the chemical solution during chemical polishing. In parallel with this dissolution process, the back surface Wb of the semiconductor wafer W is physically polished by the polishing brush 43. The polishing brush 43 preferably has polyvinyl alcohol, silicon carbide, or diamond on its polishing surface. More specifically, the polishing brush 43 preferably has a polishing surface in which abrasive grains are contained in the brush pad binder. In this case, the abrasive grains preferably include one or more of cerium (Ce), silicon carbide (SiC), and diamond (C). Furthermore, the brush pad binder is preferably made of PVA (polyvinyl alcohol), PP (polypropylene), PTFE (polytetrafluoroethylene, fluororesin), or the like.

[0067] After the sacrificial film coating, a second surface process (surface process 2; second surface treatment step) is performed on the surface Wf of the semiconductor wafer W. The second surface process includes, for example, one or more of a photolithography step, an etching step, and a film formation step. In at least one of these steps, the back surface Wb of the semiconductor wafer W is adsorbed and held by an electrostatic chuck device 80 (see Figure 1). Therefore, the back surface Wb of the semiconductor wafer W after the second surface process has irregularities formed due to contact with numerous protrusions 83 (see Figure 1) provided on the adsorption surface 82 of the adsorption stage 81 of the electrostatic chuck device 80. More specifically, when the sacrificial film 97 or protective film 100 on the back surface Wb of the semiconductor wafer W comes into contact with the protrusions 83 of the electrostatic chuck device 80 and localized friction occurs, the film material is scraped off. Recesses 92 and 102 are formed in the scraped film portions, and protrusions 91 and 101 are formed around the periphery of the recesses 92 and 102. When the film material detaches, the detached material becomes particles P (see Figure 1).

[0068] After the second surface process, a process (selective removal of sacrificial film) is performed to selectively remove the sacrificial film 97 from the back surface Wb of the semiconductor wafer W. As a result, the back surface Wb of the semiconductor wafer W becomes a surface without the sacrificial film 97. Specifically, in this example, the back surface Wb of the semiconductor wafer W becomes a surface covered with a protective film 100.

[0069] The selective removal of the sacrificial film 97 is preferably performed by chemical treatment using a chemical solution selected according to the film material of the sacrificial film 97. Specifically, if the sacrificial film 97 is an organic-rich organosilicon material, it is preferable to use a chemical solution containing an oxidizing agent such as ozone (oxidizing agent-containing chemical solution). If the sacrificial film 97 is a silicon-rich organosilicon material, it is preferable to use an alkaline chemical solution such as TMAH (tetramethylammonium hydroxide) or SC1 (ammonia hydrogen peroxide solution). In either case, the organosilicon material, which is the plastic material 96, can be dissolved and removed with the chemical solution.

[0070] One specific example of an organic-rich organosilicon material is polyimide polymer. Another specific example of a silicon-rich organosilicon material is UV-curable liquid silicone rubber, and more specifically, PDMS (polydimethylsiloxane).

[0071] According to the process of this specific example, the semiconductor wafer W has a surface Wf, which is the main surface exposed to form a pattern, and a back surface Wb, which is the main surface opposite to the surface Wf. Before exposure to form a pattern for the second surface process (surface process 2) on the surface Wf, a planarization process is performed to flatten the back surface Wb. The planarization process includes a protrusion removal step (back surface chemical polishing) in which protrusions 91 present on the back surface Wb of the semiconductor wafer W are removed by chemical polishing, and a recess filling step (sacrificial film coating) in which a fluid plastic material 96 is filled into recesses 92 present on the back surface Wb of the semiconductor wafer W after the protrusion removal step.

[0072] Therefore, the back surface Wb of the semiconductor wafer W is flattened not only by polishing the protrusions 91 but also by filling the recesses 92 with a fluid plastic material 96. As a result, when the semiconductor wafer W is exposed to form a pattern (pattern exposure), it can have high flatness on the suction stage 81 of the electrostatic chuck device 80 provided in the exposure apparatus. Moreover, by removing the protrusions 91 not only by physical polishing but also by chemical polishing, which uses a combination of physical and chemical actions, the protrusions 91 can be removed while suppressing damage to the back surface Wb of the semiconductor wafer W. Then, by filling the recesses 92 of the back surface Wb of the semiconductor wafer W from which the protrusions have been removed with a fluid plastic material 96, the back surface Wb of the semiconductor wafer W can be flattened with high precision. This makes it easier for the surface Wf of the semiconductor wafer W to fall within the depth of field range of the exposure apparatus. In other words, the positional accuracy of the surface of the semiconductor wafer W is improved. This improves the quality of pattern exposure by the exposure apparatus, and thus reduces the frequency of hot spots in the depth of field in the resist pattern. As a result, for example, the frequency of maintenance based on statistical process control (SPC) can be reduced, thereby reducing the labor required for maintenance and the utilities (factory power equipment) used for maintenance.

[0073] Furthermore, by precisely flattening the back surface Wb of the semiconductor wafer W, suction failures in the electrostatic chuck device 80 can be suppressed. In addition, the sacrificial film 97 made of the plastic material 96 can take in and adsorb at least a portion of any foreign matter present on the adsorption surface 82 of the electrostatic chuck device 80. Since this foreign matter is carried away when the semiconductor wafer W is dispensed, the adsorption surface 82 can be kept clean. As a result, suction failures can be further suppressed, and the operating rate of the device using the electrostatic chuck device 80 can be improved. In other words, the frequency of maintenance such as parts replacement and cleaning can be reduced, thereby reducing the labor required for maintenance and the utilities used for maintenance.

[0074] Furthermore, the sacrificial film 97 made of the plastic material 96 can alleviate the stress received from the protrusions 83 distributed on the adsorption surface 82 of the electrostatic chuck device 80, and if foreign matter is present on the adsorption surface 82, it can also alleviate the stress received from the foreign matter. As a result, the back surface Wb of the semiconductor wafer W can be adsorbed to the adsorption surface 82 more effectively. Moreover, high-quality processing becomes possible while suppressing the adverse effects of stress on the characteristics of the device manufactured on the semiconductor wafer W.

[0075] The material of the polishing surface of the polishing brush 43 used to remove the protrusions 91 on the back surface Wb of the semiconductor wafer W is preferably appropriately selected according to the material of the back surface Wb of the semiconductor wafer W (bare silicon, protective film 100, etc.). Specifically, the polishing brush 43 may have polyvinyl alcohol, silicon carbide, or diamond on its polishing surface. More preferably, the polishing brush 43 has a polishing surface in which abrasive grains are contained in the brush pad binder. In this case, it is preferable that the abrasive grains include one or more of cerium (Ce), silicon carbide (SiC), and diamond (C). Furthermore, it is preferable that the brush pad binder is composed of PVA (polyvinyl alcohol), PP (polypropylene), PTFE (polytetrafluoroethylene, fluororesin), etc.

[0076] Specific examples of the plastic material 96 are as described above, but in particular, using an organosilicon material is preferable because it has the effect of removing foreign matter (especially particles P) present on the adsorption stage 81 of the electrostatic chuck device 80 when the sacrificial film 97 on the back surface Wb of the semiconductor wafer W comes into contact with the adsorption stage 81. This makes it possible to eliminate or reduce the frequency of a special cleaning process for cleaning the adsorption stage 81. As a result, the operating rate of processing equipment (etching equipment, film deposition equipment, exposure equipment, etc.) using the electrostatic chuck device 80 can be increased, thus contributing to improved productivity.

[0077] The substrate processing described above is achieved, for example, by transporting the semiconductor wafer W to be processed between multiple substrate processing devices. Here, as an example, with reference to Figure 5, we will explain the case in which a substrate cleaning device 1, a film deposition device 2, a resist coating and developing device 3, an exposure device 4, and a dry etching device 5 are used.

[0078] The semiconductor wafer W to be processed is transported (for example, automatically) between the above-mentioned devices by a carrier transport device 6, which is a substrate transport device. The carrier transport device 6 is configured to transport a carrier C (see Figure 6) capable of accommodating multiple semiconductor wafers W. However, between the resist coating and developing device 3 and the exposure device 4, the semiconductor wafer W may be transported directly without the use of the carrier transport device 6.

[0079] The substrate cleaning apparatus 1 is used, for example, to clean a semiconductor wafer W before processing, to chemically polish the back surface Wb of the semiconductor wafer W (back surface chemical polishing), to coat the back surface Wb of the semiconductor wafer W with a sacrificial film 97 (sacrificial film coating), and to remove the sacrificial film 97 from the back surface Wb of the semiconductor wafer W (selective removal of sacrificial film). A specific example of the configuration of the substrate cleaning apparatus 1 will be described later.

[0080] The film deposition apparatus 2 is used for various film formations on the surface Wf of a semiconductor wafer W (film deposition process in surface processes 1 and 2), such as forming a protective film 100 on the back surface Wb of the semiconductor wafer W (back surface protective film formation). Specifically, the film deposition apparatus 2 may be an apparatus that forms various films such as insulating films on the surface Wf of a semiconductor wafer W using methods such as CVD or PVD.

[0081] The resist coating and developing apparatus 3 has the function of coating a resist onto the surface Wf of the semiconductor wafer W, baking the coated resist to form a hardened resist film, and discharging it to the exposure apparatus 4. The resist coating and developing apparatus 3 also has the function of developing the resist film after exposure by the exposure apparatus 4 to form a patterned resist film (resist pattern). In other words, the resist coating and developing apparatus 3 and the exposure apparatus 4 are responsible for the photolithography process in surface processes 1 and 2.

[0082] The exposure apparatus 4 is a device that selectively exposes a resist film formed on the surface Wf of a semiconductor wafer W according to an electronic circuit pattern. The exposure apparatus 4 may be a scanner device that exposes by scanning a long, narrow slit-shaped area laterally, such as an EUV (Extreme Ultraviolet) scanner, or it may be a device that repeatedly exposes unit areas called exposure shots (a so-called stepper).

[0083] The dry etching apparatus 5 performs an etching process (etching step of surface processes 1 and 2) on a semiconductor wafer W on which a resist pattern has been formed on its surface Wf, using the resist pattern as a mask. The dry etching apparatus 5 may be, for example, a reactive ion etching apparatus.

[0084] Figure 6 is an illustrative plan view illustrating an example configuration of a substrate cleaning apparatus 1, which is a substrate processing apparatus according to one embodiment of the present invention, and shows an example of the arrangement of multiple units comprising the substrate cleaning apparatus 1 in a plan view. The substrate cleaning apparatus 1 comprises an indexer section 10 and a process section 25. The substrate cleaning apparatus 1 further comprises a control device 15 that controls various parts of the apparatus. The control device 15 typically has a computer configuration and includes a processor (CPU) 16 and memory 17. Various operations of the substrate cleaning apparatus 1 are realized by the processor 16 executing a program stored in the memory 17.

[0085] The indexer section 10 comprises a carrier holding unit 11 and an indexer robot 12. In this embodiment, there are multiple carrier holding units 11. Each carrier holding unit 11 is configured to hold one carrier C. Typically, the carrier C is configured to hold multiple semiconductor wafers W in a horizontal position stacked vertically. Examples of carrier C include FOUP (Front Opening Unified Pod), SMIF (Standard Mechanical Interface) pod, and OC (Open Cassette). The indexer robot 12 can load and unload semiconductor wafers W into and from the carrier C held by the carrier holding unit 11, and can also load and unload semiconductor wafers W into and from the process section 25. Thus, the indexer robot 12 transports semiconductor wafers W between the carrier C and the process section 25. Specifically, the indexer robot 12 removes unprocessed semiconductor wafers W from the carrier C and transports them into the process section 25. Furthermore, the indexer robot 12 unloads the processed semiconductor wafer W from the process section 25 and loads the semiconductor wafer W into the carrier C.

[0086] The process section 25 includes a substrate standby inversion unit 26, a plurality of processing units 20, and a main transport robot 27. The main transport robot 27 accesses the substrate standby inversion unit 26 and the plurality of processing units 20 to transport semiconductor wafers W between them. More specifically, the main transport robot 27 includes a hand 28 for holding semiconductor wafers W and a hand drive mechanism 29 for moving the hand 28 horizontally and vertically and rotating it around a vertical axis. The hand drive mechanism 29 typically includes actuators such as cylinders and electric motors. The main transport robot 27 allows the hand 28 to access the substrate standby inversion unit 26 and the plurality of processing units 20 to transport semiconductor wafers W between them. More specifically, the main transport robot 27 receives unprocessed semiconductor wafers W from the substrate standby inversion unit 26 and loads the semiconductor wafers W into any of the processing units 20. Once processing by the processing unit 20 is complete, the main transport robot 27 unloads the processed semiconductor wafer W and either transports it to another processing unit 20 for further processing or to the substrate waiting inversion unit 26.

[0087] The substrate standby inversion unit 26 is a substrate standby unit that provides a standby location for semiconductor wafers W being transported between the indexer section 10 and the process section 25. The substrate standby inversion unit 26 is also a substrate inversion unit that has the function of inverting the upper and lower surfaces of the semiconductor wafers W. Specifically, the substrate standby inversion unit 26 includes a substrate holder 26a that holds one or more semiconductor wafers W horizontally, and a rotation mechanism (not shown) that rotates the substrate holder 26a around a horizontal axis of rotation to swap the upper and lower surfaces of the semiconductor wafers W held in the substrate holder 26a. The rotation mechanism typically includes an actuator such as an electric motor.

[0088] When a semiconductor wafer W is placed in a carrier C with its surface facing upwards, and processing is required on the back surface of the semiconductor wafer W, the substrate standby inversion unit 26 inverts the top and bottom surfaces of the semiconductor wafer W. That is, when the substrate standby inversion unit 26 receives an unprocessed semiconductor wafer W from the indexer robot 12, it inverts the top and bottom surfaces of the semiconductor wafer W so that the back surface Wb of the semiconductor wafer W becomes the top surface. The semiconductor wafer W is then unloaded from the substrate standby inversion unit 26 by the main transport robot 27 and loaded into the processing unit 20. Also, when the substrate standby inversion unit 26 receives a processed semiconductor wafer W from the main transport robot 27, it inverts the top and bottom surfaces of the semiconductor wafer W so that the front surface Wf of the semiconductor wafer W becomes the top surface. The semiconductor wafer W is then placed in the carrier C by the indexer robot 12. Therefore, the processed semiconductor wafer W is placed in the carrier C in a position with its surface facing upwards.

[0089] In this embodiment, the processing unit 20 is a single-wafer processing unit that processes semiconductor wafers W one at a time. The multiple processing units 20 include, for example, a chemical cleaning unit 21, a coating unit 22, and a solidification unit 23. Multiple identical processing units 20 may be provided. Alternatively, a unit capable of performing chemical cleaning and coating may be provided. Figure 6 shows one chemical cleaning unit 21, one coating unit 22, and two solidification units 23 in a plan view. However, the multiple processing units 20 may be stacked vertically and arranged three-dimensionally, and the number and arrangement are not limited to the example in Figure 6.

[0090] The chemical cleaning unit 21 performs, for example, a cleaning step of the semiconductor wafer W before surface process 1, a chemical polishing step on the back surface, a process for removing excess material during sacrificial film coating, and a selective removal step (removal step) of the sacrificial film after surface process 2. The chemical cleaning unit is an example of a chemical polishing unit. The coating unit 22 performs, for example, a coating step and an edge rinsing step during sacrificial film coating. The solidification unit 23 performs a solidification step to solidify the coated film of the plastic material during sacrificial film coating. The solidification unit 23 may also be a heat treatment unit that performs, for example, a bake treatment and a cooling treatment after baking. Alternatively, the solidification unit 23 may be an ultraviolet irradiation unit (ultraviolet treatment unit) that solidifies the plastic material by irradiating it with ultraviolet light.

[0091] Figure 7 shows an example of the configuration of the chemical cleaning unit 21. The chemical cleaning unit 21 includes a spin chuck 31 as a substrate holder that holds the semiconductor wafer W horizontally, a rotation drive mechanism 32 that rotates the spin chuck 31 around a vertical axis of rotation, a processing liquid supply unit 33 that supplies processing liquid to the semiconductor wafer W held in the spin chuck 31, and a scrubbing unit 42 that scrubs (polishes) the upper surface of the semiconductor wafer W held in the spin chuck 31.

[0092] The spin chuck 31 is located inside the processing cup 30. The rotary drive mechanism 32 typically includes an electric motor.

[0093] The processing liquid supply unit 33 includes a chemical supply unit 34 and a rinse liquid supply unit 38. The chemical supply unit 34 includes a chemical nozzle 35 that discharges chemical solution toward the upper surface of the semiconductor wafer W held in the spin chuck 31, a chemical pipe 36 that supplies chemical solution to the chemical nozzle 35, and a chemical valve 37 interposed in the chemical pipe 36 to open and close its flow path. The rinse liquid supply unit 38 includes a rinse liquid nozzle 39 that discharges rinse liquid (deionized water, carbonated water, etc.) toward the upper surface of the semiconductor wafer W held in the spin chuck 31, a rinse liquid pipe 40 that supplies rinse liquid to the rinse liquid nozzle 39, and a rinse liquid valve 41 interposed in the rinse liquid pipe 40 to open and close its flow path. The chemical nozzle 35 and / or rinse nozzle 39 may be fixed nozzles that discharge the processing liquid (chemical solution or rinse solution) toward a fixed position on the upper surface of the semiconductor wafer W, or they may be movable nozzles (so-called scan nozzles) whose liquid contact position on the upper surface of the semiconductor wafer W is variable.

[0094] By holding and rotating the semiconductor wafer W with the spin chuck 31, and supplying a chemical solution to the semiconductor wafer W with the chemical solution supply unit 34, chemical treatment can be performed on the semiconductor wafer W. Alternatively, by stopping the supply of the chemical solution and while holding and rotating the semiconductor wafer W with the spin chuck 31, a rinsing treatment can be performed by supplying a rinsing solution to the semiconductor wafer W with a rinsing solution using the rinsing solution supply unit 38, thereby replacing the chemical solution on the semiconductor wafer W with the rinsing solution. Finally, by stopping the supply of the rinsing solution and accelerating the rotation of the spin chuck 31 (i.e., the rotation of the semiconductor wafer W), a drying treatment (spin drying) can be performed to shake off the rinsing solution adhering to the semiconductor wafer W.

[0095] The chemical solution supply unit 34 may be configured to supply multiple types of chemical solutions, and may be equipped with multiple chemical solution nozzles 35 and chemical solution supply systems corresponding to the number of types of chemical solutions. The chemical solution supply unit 34 is configured to supply the chemical solutions necessary for, for example, the cleaning process of the semiconductor wafer W before surface process 1, the back surface chemical polishing process, the excess material removal process during sacrificial film coating, and the selective sacrificial film removal process (removal process) after surface process 2.

[0096] The scrub unit 42 includes a polishing brush 43 (scrub brush), a rocking arm 44 that holds the polishing brush 43, and an arm drive mechanism 45 that drives the rocking arm 44. The arm drive mechanism 45 moves the rocking arm 44 up and down and rocks it about a vertical axis. For such motion, the arm drive mechanism 45 is equipped with an actuator such as a cylinder or an electric motor. As the rocking arm 44 is driven by the arm drive mechanism 45, the polishing brush 43 can contact the upper surface of the semiconductor wafer W held in the spin chuck 31 and move radially over the semiconductor wafer W. As this motion is performed while the semiconductor wafer W is rotated by the spin chuck 31, the polishing brush 43 can scrub the upper surface of the semiconductor wafer W while scanning it.

[0097] The polishing brush 43 can be used to scrub the back surface Wb of the semiconductor wafer W in the back surface chemical polishing process and the excess material removal process. That is, by supplying an appropriate chemical solution from the chemical solution supply unit 34 to the upper surface of the semiconductor wafer W in the chemical solution supply process, and simultaneously performing a scrubbing process by scrubbing the upper surface of the semiconductor wafer W with the polishing brush 43, the back surface chemical polishing process or the excess material removal process can be performed.

[0098] Figure 8 shows an example of the configuration of the coating unit 22. The coating unit 22 includes a spin chuck 51 as a substrate holder for holding the semiconductor wafer W horizontally, a rotation drive mechanism 52 for rotating the spin chuck 51 around a vertical axis, a coating liquid supply unit 53 for supplying coating liquid to the upper surface of the semiconductor wafer W, and an edge rinse unit 57 for cleaning the peripheral edge of the semiconductor wafer W.

[0099] The spin chuck 51 is preferably configured to hold the semiconductor wafer W with its peripheral edge exposed around its entire circumference. The semiconductor wafer W is preferably held by a mechanism that grips portions of the wafer W other than the device surface, such as a chuck pin gripping mechanism as illustrated in Figure 7. The chuck pin gripping mechanism preferably includes a chuck pin opening / closing mechanism to allow switching between a state in contact with the wafer W and a state of non-contact in order to rinse the end face of the semiconductor wafer W. If the device surface is protected by a protective film such as a sacrificial film and can withstand mechanical damage, the device surface may be held by suction using a vacuum chuck. For example, a vacuum chuck that suctions and holds the central portion of the lower surface of the semiconductor wafer W may be used. The spin chuck 51 is located inside the processing cup 50. The rotational drive mechanism 52 typically includes an electric motor.

[0100] The coating liquid supply unit 53 includes a coating liquid nozzle 54 for discharging the coating liquid, a coating liquid piping 55 for supplying the coating liquid to the coating liquid nozzle 54, and a coating liquid valve 56 interposed in the coating liquid piping 55 for opening and closing its flow path. The coating liquid nozzle 54 may be a fixed nozzle that discharges the coating liquid toward the rotation center of the semiconductor wafer W, or it may be a movable nozzle (so-called scanning nozzle) that discharges the coating liquid while changing the liquid application position to scan the upper surface of the semiconductor wafer W in the radial direction. The coating liquid is a fluid plastic material.

[0101] As the semiconductor wafer W is rotated by the spin chuck 51, the coating liquid is discharged toward its upper surface. The coating liquid that lands on the upper surface of the semiconductor wafer W is then subjected to centrifugal force and spreads across the entire surface. This allows the coating liquid to be applied to the upper surface of the semiconductor wafer W. By holding the semiconductor wafer W with its back surface facing upwards in the spin chuck 51, the coating liquid can be applied to the back surface Wb of the semiconductor wafer W, forming a coating film. This coating film forms a sacrificial film that is embedded in the recesses on the back surface of the semiconductor wafer W.

[0102] The edge rinsing unit 57 selectively removes coating liquid adhering to the peripheral edge (especially the peripheral edge) of the semiconductor wafer W. The edge rinsing unit 57 may be equipped with a cleaning brush that contacts the peripheral edge of the semiconductor wafer W. The edge rinsing unit 57 may also be equipped with a cleaning liquid nozzle that discharges cleaning liquid toward the peripheral edge of the semiconductor wafer W. For example, by operating the edge rinsing unit 57 while rotating the semiconductor wafer W with the spin chuck 51, edge rinsing can be performed over the entire circumference of the peripheral edge of the semiconductor wafer W.

[0103] Figure 9 shows an example configuration of the solidification unit 23. In this example, the solidification unit 23 is a heat treatment unit that includes a heating unit 23H (bake unit) and a cooling unit 23C. In this example, the solidification unit 23 further includes a local transport device 23R for transporting semiconductor wafers W within the unit.

[0104] The heating unit 23H includes a hot plate 60 on which a semiconductor wafer W is placed and which heats the semiconductor wafer W. Typically, the hot plate 60 includes a plate body 61 with high thermal conductivity and a heater 62 in contact with the plate body 61. In an embodiment, the heating unit may also use a light source, such as an LED light source or a halogen lamp, placed above the semiconductor wafer W to heat the semiconductor wafer W. In this case, the surface to which the coating liquid is applied is processed facing the light source.

[0105] A transfer unit 63 may be provided for transferring semiconductor wafers W between the local transport device 23R and the hot plate 60. The transfer unit 63 may include a support pin 64 that moves up and down while supporting the semiconductor wafers W from below by penetrating the heating surface of the hot plate 60, and a pin lifting mechanism 65 that moves the support pin 64 up and down. The pin lifting mechanism 65 is equipped with an actuator such as a cylinder or electric motor as a drive source.

[0106] The cooling unit 23C is a unit that cools the semiconductor wafer W, which has been heat-treated by the heating unit 23H, to, for example, room temperature. The cooling unit 23C includes a cool plate 70 on which the semiconductor wafer W is placed and which cools the semiconductor wafer W. The cool plate 70 typically includes a plate body 71 with high thermal conductivity and a cooling element 72 in contact with the plate body 71. The cooling element 72 may be an electrically operated cooling element such as a Peltier element, or a non-electric cooling element such as a cooling water channel. A transfer unit 73 may be provided for transferring the semiconductor wafer W between the main transfer robot 27 and the local transfer device 23R and the cool plate 70. The transfer unit 73 may include a support pin 74 that moves up and down while supporting the semiconductor wafer W from below by moving up and down through the heated surface of the cool plate 70, and a pin lifting mechanism 75 that moves the support pin 74 up and down. The pin lifting mechanism 75 is equipped with an actuator such as a cylinder or an electric motor as a drive source.

[0107] The local transport device 23R includes, for example, a local transport hand 77 for holding a semiconductor wafer W, and a hand drive mechanism 78 for driving the local transport hand 77. The hand drive mechanism 78 typically includes an actuator such as a cylinder or an electric motor.

[0108] For example, the main transport robot 27 passes the semiconductor wafer W to the support pin 74 of the cooling unit 23C. At this time, the support pin 74 is in the upper position, and its tip is above the cool plate 70. The local transport device 23R receives the semiconductor wafer W from the support pin 74 and passes it to the support pin 64 of the heating unit 23H. At this time, the support pin 64 is in the upper position, and its tip is above the hot plate 60. The support pin 64 descends and the semiconductor wafer W is placed on the heating surface (upper surface) of the hot plate 60, thereby performing a bake process on the semiconductor wafer W. After the bake process, the support pin 64 rises and pushes up the semiconductor wafer W, at which point the local transport device 23R receives the semiconductor wafer W, transports it to the cooling unit 23C, and passes it to the support pin 74. The support pin 74 descends and the semiconductor wafer W is placed on the cooling surface (upper surface) of the cool plate 70, thereby cooling the semiconductor wafer W. After the semiconductor wafer W has cooled, the support pins 74 rise and push up the semiconductor wafer W, at which point the main transport robot 27 receives the semiconductor wafer W from the support pins 74 and transports it out of the solidification unit 23.

[0109] In this example, the semiconductor wafer W is transported between the cooling unit 23C and the heating unit 23H by the local transport device 23R, but this transport may also be performed by the main transport robot 27.

[0110] Figure 10 shows another example of the solidification unit 23 configuration. In this example, the solidification unit 23 is an ultraviolet irradiation unit (an example of an ultraviolet processing unit) that irradiates a semiconductor wafer W with ultraviolet light. In this example, the solidification unit 23 includes a flat support plate 111 that supports the semiconductor wafer W and an ultraviolet lamp 112 positioned above the support plate 111. With the semiconductor wafer W supported on the support plate 111, ultraviolet irradiation processing can be performed by irradiating the semiconductor wafer W with ultraviolet light from the ultraviolet lamp 112. If a coating film of an ultraviolet-curable plastic material is formed on the back surface Wb (top surface) of the semiconductor wafer W, the coating film can be solidified by irradiating it with ultraviolet light.

[0111] A transfer unit 113 may be provided for transferring the semiconductor wafer W between the main transport robot 27 and the support plate 111. The transfer unit 113 may include a support pin 114 that moves up and down while supporting the semiconductor wafer W from below by penetrating the support surface (upper surface) of the support plate 111, and a pin lifting mechanism 115 that moves the support pin 114 up and down. The pin lifting mechanism 115 is equipped with an actuator such as a cylinder or electric motor as a drive source.

[0112] Next, examples of the operation of the substrate cleaning apparatus 1 will be described. These examples of operation are realized by the control operation of the control device 15. That is, the control device 15 is programmed to control each part of the substrate cleaning apparatus 1 in order to realize these examples of operation.

[0113] The operation of the substrate cleaning apparatus 1 during the cleaning process for cleaning the semiconductor wafer W before the back surface protective film formation process is as follows. Specifically, when the carrier C containing the semiconductor wafer W before the back surface protective film formation process is loaded into the carrier holding unit 11, the indexer robot 12 loads it out and passes it to the substrate standby inversion unit 26. The main transport robot 27 loads the semiconductor wafer W and loads it into the chemical cleaning unit 21. The chemical cleaning unit 21 performs a cleaning process on the semiconductor wafer W. This process includes a chemical treatment that supplies a chemical solution to the semiconductor wafer W while rotating it, a rinsing treatment that replaces the chemical solution adhering to the semiconductor wafer W with a rinsing solution while rotating it, and a drying treatment (spin drying) that accelerates the rotation of the semiconductor wafer W to shake off the rinsing solution adhering to it. After such a process is completed, the main transport robot 27 loads the semiconductor wafer W from the chemical cleaning unit 21 and loads it into the substrate standby inversion unit 26. The semiconductor wafer W is picked up by the indexer robot 12 and loaded into the carrier C. The substrate waiting inversion unit 26 only needs to provide a temporary waiting area for the semiconductor wafer W being transported between the indexer robot 12 and the main transport robot 27, and does not need to invert the top and bottom surfaces of the semiconductor wafer W.

[0114] The following is an example of the operation of the substrate cleaning apparatus 1 during the back surface chemical polishing process and the sacrificial film coating process. When the carrier C containing the semiconductor wafer W that has completed surface process 1 is loaded into the carrier holding section 11, the indexer robot 12 loads it out and passes it to the substrate standby inversion unit 26. The substrate standby inversion unit 26 performs an inversion operation to flip the top and bottom surfaces of the semiconductor wafer W so that the back surface Wb of the semiconductor wafer W becomes the top surface. After that, the main transport robot 27 loads the semiconductor wafer W and loads it into the chemical cleaning unit 21. The chemical cleaning unit 21 performs a back surface chemical polishing process on the semiconductor wafer W, removing the protrusions present on the back surface Wb of the semiconductor wafer W by using a combination of chemical and physical actions (protrusion removal process). Subsequently, the chemical cleaning unit 21 rotates the semiconductor wafer W while supplying a processing solution (chemical solution and / or rinsing solution) to the semiconductor wafer W to wash away any residue on the semiconductor wafer W, and then accelerates the rotation of the semiconductor wafer W to perform a drying process to shake off the rinsing solution, thus completing the process. At this point, the main transport robot 27 removes the semiconductor wafer W from the chemical cleaning unit 21 and transports it to the coating unit 22. The coating unit 22 rotates the semiconductor wafer W and discharges a coating solution (a fluid plastic material) onto its upper surface. This forms a coating film that covers the back surface of the semiconductor wafer W. After that, an edge rinsing process is performed to clean the coating film adhering to the periphery of the semiconductor wafer W. After the rotation of the semiconductor wafer W stops, the main transport robot 27 removes the semiconductor wafer W from the coating unit 22 and transports it to the solidification unit 23. The solidification unit 23 performs a solidification process to solidify the coating film formed on the back surface of the semiconductor wafer W. Subsequently, the main transport robot 27 transports the semiconductor wafer W from the solidification unit 23 to the chemical cleaning unit 21. The chemical cleaning unit 21 performs an excess material removal process to remove excess plastic material from the back surface Wb of the semiconductor wafer W. Specifically, while rotating the semiconductor wafer W, a chemical solution is supplied to the back surface Wb of the semiconductor wafer W, and the back surface Wb of the semiconductor wafer W is polished by the polishing brush 43. This removes excess plastic material from the back surface Wb of the semiconductor wafer W.Subsequently, while rotating the semiconductor wafer W, the semiconductor wafer W is treated with a processing solution (chemical solution and / or). Rinse solution A chemical solution is supplied to wash away any residue from the semiconductor wafer W. After that, the supply of the processing solution is stopped, and the rotation of the semiconductor wafer W is accelerated to perform a drying process that shakes off any remaining liquid components from the semiconductor wafer W. When the rotation of the semiconductor wafer W is stopped, the main transport robot 27 removes the processed semiconductor wafer W from the chemical cleaning unit 21 and carries it to the substrate standby inversion unit 26. The substrate standby inversion unit 26 performs an inversion process to flip the semiconductor wafer W so that the top and bottom surfaces are reversed, with the surface Wf facing upwards. The semiconductor wafer W is then removed by the indexer robot 12 and carried to the carrier C.

[0115] An example of the operation of the substrate cleaning apparatus 1 during the sacrificial film selective removal process is as follows: When the carrier C containing the semiconductor wafer W after the surface process 2 is loaded into the carrier holding unit 11, the indexer robot 12 loads it and passes it to the substrate standby inversion unit 26. The substrate standby inversion unit 26 performs an inversion operation to flip the top and bottom surfaces of the semiconductor wafer W so that the back surface Wb of the semiconductor wafer W becomes the top surface. After that, the main transport robot 27 loads the semiconductor wafer W and loads it into the chemical cleaning unit 21. The chemical cleaning unit 21 performs a process to selectively remove the sacrificial film from the back surface Wb (top surface) of the semiconductor wafer W. This process includes a chemical treatment that supplies a chemical solution for selectively removing the sacrificial film to the semiconductor wafer W while rotating the semiconductor wafer W, a rinsing treatment that replaces the chemical solution adhering to the semiconductor wafer W with a rinsing solution while rotating the semiconductor wafer W, and a drying treatment (spin drying) that accelerates the rotation of the semiconductor wafer W to shake off the rinsing solution adhering to the semiconductor wafer W. Once this process is complete, the main transport robot 27 removes the semiconductor wafer W from the chemical cleaning unit 21 and loads it into the substrate standby inversion unit 26. The substrate standby inversion unit 26 performs an inversion process on the semiconductor wafer W, flipping its top and bottom surfaces so that the surface Wf is the top surface. The semiconductor wafer W is then removed by the indexer robot 12 and loaded into the carrier C.

[0116] While embodiments of this invention have been described above, this invention can be implemented in other forms as well.

[0117] For example, the substrate to be processed is not limited to semiconductor wafers; it may also be other types of substrates such as flat display panel substrates or photomask substrates.

[0118] Furthermore, while the above-described embodiment mainly explained the problems and solutions arising from semiconductor wafers being adsorbed onto the adsorption stage of an electrostatic chuck device, similar problems exist and similar solutions can be applied when semiconductor wafers or other substrates are adsorbed by a vacuum suction type adsorption stage.

[0119] Furthermore, various design modifications can be made within the scope of the matters described in the patent claims. [Explanation of Symbols]

[0120] 1: Circuit board cleaning device 2: Film deposition equipment 3: Resist coating and developing device 4: Exposure equipment 5: Dry etching equipment 6: Carrier conveying device 10: Indexersection 11: Carrier holding part 12: Indexer Robot 15: Control device 20: Processing Unit 21: Chemical cleaning unit 22: Coating Unit 23: Solidification Unit 23C: Cooling Unit 23H: Heating unit 25: Process Section 26: Circuit board standby inversion unit 27: Main transport robot 31: Spin Chuck 33: Processing liquid supply unit 34: Chemical solution supply unit 38: Rinse fluid supply unit 42: Scrub Unit 43: Polishing brush 51: Spin Chuck 53: Coating liquid supply unit 57: Edge Rinse Unit 60: Hot plate 70: Cool Plate 77: Local conveyor hand 80: Electrostatic Chuck Device 81: Adsorption stage 82: Adsorption surface 83: Convex part 91: Convex part 92: Recess 93: Flat part 96 :Plastic material 97: Sacrificial membrane 100: Protective film 101: Convex part 102: Recess 111: Support plate 112: UV lamp C: Carrier P: Particle W: Semiconductor wafer Wb: Back side Wf: Surface

Claims

1. A method for processing a substrate having a surface which is a main surface exposed to form a pattern and a back surface which is a main surface opposite to the surface, The process includes a planarization treatment to flatten the back surface before exposure to form a pattern on the surface, The aforementioned planarization process is, A step of removing protrusions present on the back surface of the substrate by chemical polishing, The process includes, after the protrusion removal step, a recess filling step in which a fluid, plastic material is embedded in the recesses present on the back surface of the substrate, The recess filling step is, A coating step of applying a fluid plastic material to the back surface of the substrate, The process includes, after the coating step, an excess material removal step in which the back surface of the substrate is scrubbed with a brush to remove excess plastic material, Substrate processing method.

2. The aforementioned protrusion removal step is, A chemical solution supply step of supplying a chemical solution to the back surface of the substrate, A substrate processing method according to claim 1, comprising a scrubbing step of scrubbing the back surface of the substrate to which the chemical solution has been supplied by the chemical solution supply step with an abrasive brush.

3. The substrate treatment method according to claim 2, wherein the chemical solution comprises one or more selected from the group consisting of hydrofluoric acid, hydrofluoric acid-hydrogen peroxide solution, ozone-containing hydrofluoric acid solution, ammonia-hydrogen peroxide solution, ozone-containing sulfuric acid solution, hydrochloric acid-hydrogen peroxide solution, ozonated water, sulfuric acid-hydrogen peroxide solution, and hydrogen peroxide solution.

4. The substrate processing method according to claim 2 or 3, wherein the polishing brush has a polishing surface in which abrasive grains are contained in the brush pad binder.

5. The substrate processing method according to claim 4, wherein the abrasive grains include one or more of cerium, silicon carbide, and diamond.

6. The substrate processing method according to any one of claims 1 to 5, wherein the plastic material includes either a resin material or a silicon-based material or a mixture thereof.

7. The substrate processing method according to claim 6, wherein the resin material includes polyimide.

8. The substrate processing method according to claim 6 or 7, wherein the silicon-based material includes a methyl-based silicon coating material.

9. The substrate processing method according to any one of claims 1 to 5, wherein the plastic material includes an organosilicon material.

10. A substrate processing method according to any one of claims 1 to 9, further comprising a solidification step of solidifying the plastic material after the coating step and before the excess material removal step.

11. The substrate processing method according to claim 10, wherein the solidification step includes at least one of a bake treatment in which the plastic material is heated to 100°C to 400°C, and an ultraviolet treatment in which the plastic material is irradiated with ultraviolet light.

12. After the recess filling step, a surface treatment step is performed to treat the surface of the substrate, A substrate processing method according to any one of claims 1 to 11, further comprising a removal step of removing the plastic material from the back surface of the substrate after the surface treatment step.

13. The substrate processing method according to claim 12, wherein the removal step includes a step of supplying an alkaline chemical solution or an oxidizing agent-containing chemical solution to the back surface of the substrate to dissolve the plastic material.

14. The aforementioned surface treatment step is The process of adsorbing and holding the back surface of the substrate onto an adsorption stage, A substrate processing method according to claim 12 or 13, comprising the step of pattern exposure of the surface of the substrate held in the adsorption stage.

15. Before the flattening process, A substrate processing method according to any one of claims 1 to 14, further comprising the step of adsorbing and holding the back surface of the substrate on an adsorption stage to process the surface of the substrate.

16. A substrate processing apparatus that performs a treatment on a substrate having a surface which is the main surface on which a pattern is formed and a back surface which is the main surface opposite to the surface, before exposure for forming the pattern, A chemical polishing unit that supplies a chemical solution to the back surface of the substrate while scrubbing the back surface with a polishing brush, A coating unit that supplies a coating liquid containing a fluid plastic material to the back surface of the substrate and forms a coating film containing the plastic material, The aforementioned plastic material includes an organosilicon material, and is a substrate processing apparatus.

17. The substrate processing apparatus according to claim 16, further comprising a transport robot for transporting the substrate processed by the chemical polishing unit to the coating unit.

18. The substrate processing apparatus according to claim 16 or 17, further comprising a solidification unit for processing a substrate on which a coating film of the plastic material is formed on the back surface, and for solidifying the coating film.

19. The substrate processing apparatus according to claim 18, wherein the solidification unit includes at least one of a heating unit for heating the substrate and an ultraviolet treatment unit for irradiating the substrate with ultraviolet light.

20. The substrate processing apparatus according to any one of claims 16 to 19, wherein the chemical solution comprises one or more selected from the group consisting of hydrofluoric acid, hydrofluoric acid hydrogen peroxide solution, ozone-containing hydrofluoric acid solution, ammonia hydrogen peroxide solution, ozone-containing sulfuric acid solution, hydrochloric acid hydrogen peroxide solution, ozonated water, sulfuric acid hydrogen peroxide solution, and hydrogen peroxide solution.

21. The substrate processing apparatus according to any one of claims 16 to 20, wherein the polishing brush has a polishing surface in which abrasive grains are contained in the brush pad binder.

22. The substrate processing apparatus according to claim 21, wherein the abrasive grains include one or more of cerium, silicon carbide, and diamond.

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