JP4509122B2 - Apparatus and method for cleaning a substrate - Google Patents

Description

  The present invention relates to semiconductor manufacturing, and more particularly to an apparatus and method used for substrate processing.

  In manufacturing a semiconductor element, it is necessary to perform cleaning of a substrate (for example, a semiconductor wafer). For example, the process of processing electronic elements on a semiconductor wafer involves a complex process of depositing and removing many layers. Typically, the patterning of the layer material includes the step of applying an organic photoresist on the semiconductor wafer. After etching the material of interest by plasma chemistry, the semiconductor needs to be cleaned to remove the organic photoresist. If the organic photoresist is not removed, the organic photoresist will contaminate the semiconductor wafer and damage electronic devices on the semiconductor wafer. Furthermore, after a chemical mechanical polishing (CMP) operation, residual particles or films are left on the surface of the semiconductor wafer. Similarly, these residual particles or films can cause defects that can render devices on the wafer inoperable, such as scratches on the wafer surface. To avoid device damage, the wafer needs to be cleaned even after the CMP operation. That is, the cleaning operation is a very important process that is repeated many times through the process of processing the semiconductor element.

  FIG. 1 is a simplified side view showing a conventional system used for cleaning semiconductor wafers. The cleaning system includes two brushes 110 and the two brushes are configured to receive the semiconductor wafer 112 therebetween. A foam 114 is supplied to the surface of the semiconductor wafer 112, and the brush 110 rotates to rub the surface of the semiconductor wafer to remove particles and films. The problem with supplying the foam 114 in an open environment is that the foam growth is disturbed around the brush 110, so that the foam cannot be directed to a specific surface area of the semiconductor wafer 112. In other words, the flow of foam 114 is difficult to control when supplied in an open environment. Furthermore, different properties of foam 114 have different cleaning capabilities, and the properties of foam 114 are difficult to control when supplied in an open environment. Furthermore, since a large amount of foam is required to ensure a uniform distribution over the surface of the semiconductor wafer 112, the supply of the foam 114 in an open environment is wasteful.

  In view of the above, it is necessary to save the use of foam and to control the physical properties and flow of the foam as it is supplied to the surface of the semiconductor wafer.

  In general, the present invention provides an apparatus and method for cleaning a substrate to meet these needs. It should be understood that the present invention can be implemented in various forms including a process, apparatus, system, computer readable medium, or device. In the following, several embodiments of the present invention will be described.

  According to a first aspect of the invention, there is provided an apparatus for use in processing a substrate. The device comprises a brush container that extends over a length. The brush container is configured to be disposed above the surface of the substrate, and has an opening region configured to be disposed in proximity to the substrate. The open area extends over the length of the brush container and allows foam from within the brush container to contact the surface of the substrate.

  According to a second aspect of the present invention, a brush container for use in processing a substrate is provided. The brush container includes an elongated container configured to surround the brush. The elongate container is configured to be disposed above the surface of the substrate and has opposite ends defining a length. Further, the elongated container has an open area along the length of the elongated container. The open area is configured to be disposed above the surface of the substrate, allowing the surface of the brush to contact the surface of the substrate.

  According to a third aspect of the present invention, a substrate cleaning system is provided. The system includes a first brush container and a first brush partially enclosed within the first brush container. The first partially enclosed brush is configured to be disposed above the surface of the substrate. The system further includes a first drive roller and a second drive roller, the first and second drive rollers receiving the edge of the substrate and the first partially enclosed brush. When the substrate is disposed below, the substrate is supported and rotated.

  According to a fourth aspect of the present invention, a method for cleaning a substrate is provided. In this method, foam is supplied to the surface of the substrate. Next, the surface of the substrate is rubbed with a brush. Next, pressure is applied to the foam and the pressurized foam is sent to produce a dense foam. The process of rubbing the surface of the substrate with the brush and sending the pressurized foam across the surface of the substrate facilitates the removal of particles from the surface of the substrate.

  Other aspects and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.

  An apparatus and method invention for cleaning a substrate is disclosed. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without some or all of these specific details. In addition, in order to avoid unnecessarily obscuring the present invention, description of known processing operations is omitted.

  The embodiments described herein provide a brush container for enclosing the brush and foam. In particular, the brush container is configured to contain and control foam flow and physical properties. As described in detail later, the shape of the brush container causes various cleaning effects within the brush container.

  FIG. 2A is a perspective view illustrating a brush 210 partially enclosed within a brush container 212, in accordance with one embodiment of the present invention. For illustration purposes, the brush container 212 includes a cut-out portion in a reference region 220 that shows the brush 210 partially enclosed within the brush container. The brush 210 removes particles by rotating and wipes it from the surface of the substrate. The brush container 212 may be configured to enclose any suitable brush 210 used in processing the substrate. For example, as shown in FIG. 2A, an example brush 210 has a spline shape with a series of parallel continuous ridges perpendicular to the curved brush surface. Another example suitable brush 210 has a hump-like structure with a set of multiple cylinders raised perpendicular to the curved brush surface.

  The brush container 212 is an elongated member that extends over a length 218. As shown in FIG. 2A, the length 218 of the brush container 212 extends over the length of the brush 210. However, in other embodiments, the length 218 of the brush container 212 may be shorter or longer than the length of the brush 210. FIG. 2A illustrates a tubular brush container 212 according to one embodiment of the present invention. However, the brush container 212 does not necessarily have to be “tubular”, as long as the brush container is configured to allow the brush 210 to be partially enclosed, for example, a rectangular cross section, an elliptical cross section, etc. May have any suitable configuration, shape, and / or size, such as an elongated member having a triangular cross-section, circular cross-section, and the like.

  As will be described in detail later, the brush container 212 includes an open region 222, and in one embodiment, further includes two opposing flanges 214 that extend to opposite sides of the open region 222 along its length. The brush container 212 is made of a chemically inert material. Examples of the chemically inert material include plastic, delrin, polyvinylidene fluoride (PVDF), polyethylene terephthalate (PET), and the like.

  2B is a side view of the brush 210 and brush container 212 shown in FIG. 2A, in accordance with one embodiment of the present invention. Here, the brush 210 partially surrounded by the brush container 212 is disposed on the substrate 216. As shown in FIG. 2B, the brush container 212 includes an open region 222 and two opposing flanges 214. The open area 222 is configured to be positioned proximate to the surface of the substrate 216 and allows the surface of the brush 210 to contact the surface of the substrate. In one embodiment, the open region 222 extends along the entire length of the brush container 212. In another embodiment, the length of the open region 222 is shorter than the length of the brush container 212.

  Further, the flange 214 extends radially outward from the outer surface of the brush container 212. Each flange 214 extends along one side of the open area 222 along its length. In one embodiment, each flange 214 extends along the entire length of the open region 222. In another embodiment, the length of each flange 214 is shorter than the length of the open region 222. Each flange 214 has a surface substantially parallel to the surface of the substrate 216. As used herein, the term “approximately” means that the angle between the surface of each flange 214 and the surface of the substrate 216 ranges from about 0 degrees to about ± 45 degrees. . As shown in FIG. 2B, the brush container 212 includes two flanges 214 at both ends. However, in another embodiment, the brush container 212 may have one flange 214 instead of two flanges.

  FIG. 3 is a perspective view illustrating a substrate cleaning system according to an embodiment of the present invention. As shown in FIG. 3, the substrate cleaning system includes two brushes 210 partially surrounded by a brush container 212, two drive rollers 310, and a substrate 216. The drive roller 310 receives the edge of the substrate 216 and supports and rotates the substrate. The two partially enclosed brushes 210 face each other so that the substrate 216 is received between the two brushes. FIG. 3 shows the use of two partially enclosed brushes 210 for cleaning the substrate 216. However, in another embodiment, one partially enclosed brush 210 may be used to clean the substrate 216. In yet another embodiment, the substrate cleaning system comprises two brushes, one brush surrounded by a brush container 212 and the other brush not surrounded by a brush container.

  As will be described in detail later, the substrate cleaning system cleans the substrate 216 using foam. Many bubbles aggregate to form a foam. A bubble is a two-phase system in which a gas is surrounded by a liquid. The liquid forms a film or coating that holds and surrounds the gas. Within the foam, liquid is also present in the space between the bubbles. In one embodiment, each brush 210 is made of a highly porous foam, such as polyvinyl alcohol (PVA), and can be used for foam generation and application. Gas and liquid are supplied to the brush 210 under pressure through a conduit 312 to produce foam within the brush container 212. Gases and liquids mix within the porous PVA brush 210 to produce a foam. In another embodiment, pre-generated foam is supplied to brush 210 through conduit 312. A drive roller 310 rotates the substrate 216 to spread the foam across the entire surface of the substrate 216. Alternatively, the foam may be spread by the brush 210 moving across the surface of the substrate 216. The foam may be further spread by a combination of rotation of the substrate 216 and movement of the brush 210 across the surface of the substrate.

  FIG. 4 is a side view showing partially enclosed brush 210 and foam 410 in accordance with one embodiment of the present invention. As shown in FIG. 4, the brush 210 is disposed above the substrate 216, and the brush container 212 partially surrounds the brush and the foam 410. The brush 210 and foam 410 containers form different regions 412, 414, 416 that clean the surface of the substrate 216. Within the region defined as region A 412, the surface of the brush 210 contacts the surface of the substrate 216. As the brush 210 rotates, the brush physically rubs the surface of the substrate 216 to remove particles. As a result, in the region A 412, the surface of the substrate 216 is cleaned by rubbing.

On the other hand, in the region defined as region B 414 , the surface of the substrate 216 is mainly cleaned by chemical treatment with the foam 410. The open area 222 of the brush container 212 allows foam 410 from within the brush container to contact the surface of the substrate 216. As described above, the foam 410 is composed of liquid and gaseous bubbles. When bubbles in foam 410 rupture on the surface of substrate 216, the rupture releases the gas, and the gas and liquid are in direct contact with the surface of substrate 216. A chemical reaction between the gas, the liquid, and the surface of the substrate 216 facilitates the removal of particles and material layers (eg, organic material layers) from the surface of the substrate.

In order to chemically treat the surface of the substrate 216 with foam 410, the gas reacts chemically when in direct contact with another material or promotes a chemical reaction or any of such gases. A combination is preferred. Examples of gases that react with contaminants include ozone (O ₃ ), oxygen (O ₂ ), hydrochloric acid (HCl), hydrofluoric acid (HF), and non-nitrogen (N ₂ ) and argon (Ar). A reactive gas may be mentioned. The gas may include any combination of gases as shown below: for example, ozone (O ₃ ) and nitrogen (N ₂ ); ozone (O ₃ ) and argon (Ar); ozone (O ₃ ), Oxygen (O ₂ ), and nitrogen (N ₂ ); ozone (O ₃ ), oxygen (O ₂ ), and argon (Ar); ozone (O ₃ ), oxygen (O ₂ ), nitrogen (N ₂ ), and Argon (Ar); oxygen (O ₂ ) and argon (Ar); oxygen (O ₂ ) and nitrogen (N ₂ ); oxygen (O ₂ ), argon (Ar) and nitrogen (N ₂ ). In one embodiment of the present invention, ozone is used as a gas because it chemically reacts with the organic material on the surface of the substrate 216 when mixed with water. The organic material may be an organic photoresist material commonly used in semiconductor photolithography operations. Nitrogen may be combined with ozone to increase the concentration of ozone in the foam.

The liquid used to produce the foam 310 is a liquid or combination of such liquids that chemically reacts or promotes a chemical reaction when in direct contact with another material. The liquid may be a semi-aqueous or aqueous solution of deionized water (DIW) containing a suitable cleaning fluid. Examples of liquids include: water (H ₂ O); deionized water (DIW); water (H ₂ O) and cleaning fluid; water (H ₂ O) and surfactants; water (H ₂ O), cleaning fluid, and surfactant; deionized water (DIW) and surfactant; deionized water (DIW), cleaning fluid, and surfactant. As described above, in one embodiment of the present invention, water is used as a liquid because it allows or facilitates a chemical reaction between ozone and the organic photoresist material.

  Within the region defined as region C 416, the surface of the substrate 216 is primarily cleaned by attracting particles to the bubble gas / liquid interface. As shown in FIG. 4, the space between the surface of each flange 214 and the surface of the substrate 216 forms a gap 224. The gap 224 is maintained to cause a non-Newtonian flow field. In one embodiment, the size of gap 224 ranges from about 0.1 mm to about 5 mm. As used herein, the term “about” means that certain dimensions and parameters may vary within acceptable manufacturing tolerances for a given application. In one embodiment, the allowable manufacturing tolerance is ± 10%.

  Within the brush container 212, pressure is applied to the foam 410 and the foam is sent to the gap 224 (ie, region C 416) to create a dense foam. A dense foam is created by applying a force to compress the foam 410. When compressed in the gap 224, the foam in the foam 410 deforms and rearranges into a more densely packed configuration. As a result, the pressure and shape of the gap 224 causes the foam 410 to change from a metastable state to a more stable state within region C 416.

  When pressure causes foam 410 in brush container 212 to be fed through gap 224, a shear force is locally induced between the foams of the dense foam. The shear forces cause the bubbles to move locally relative to each other. Explosive energy is released by local movement of bubbles caused by shear forces, and this energy is transmitted to the surface of the substrate 216 to facilitate removal of particles from the substrate surface. Specifically, the foam in a dense foam tends to be in a minimum energy state, at which time all angles between the foams are about 120 degrees. When a bubble in the minimum energy state passes over another bubble due to shear forces, the angle between the bubbles changes, and the energy state increases due to the change in angle. As a result, the change in angle between the bubbles is equivalent to the change in energy. In this way, energy is released by local rearrangement of the bubbles within the dense foam, rather than the bursting of the bubbles.

  According to FIG. 4, the brush container 212 may further comprise a removal conduit 450 disposed within the flange 214, in accordance with one embodiment of the present invention. The removal conduit 450 is configured to remove foam 410, liquid, particles, etc. from the surface of the substrate 216 by a vacuum action. In another embodiment, the conduit 450 may be configured to supply deionized water (DIW) and / or a chemical rinse agent to facilitate foam removal. In yet another embodiment, an additional conduit 450 provides additional agent and / or gas, such as isopropyl alcohol (IPA), to reduce the surface tension of the liquid at the surface of the water as a means to remove the liquid from the surface of the substrate 216. It may be reduced.

  5A and 5B are enlarged side views showing the gap region shown in FIG. 4 in accordance with one embodiment of the present invention. As shown in FIGS. 5A and 5B, the gap region shows the brush 210 partially enclosed within the brush container 212 being disposed above the substrate 216. The brush container 212 includes a flange 214, and a space between the surface of the flange and the surface of the substrate 216 forms a gap 224. Different gap 224 shapes may be used to manipulate the mechanical properties and dimensions of foam 410 and foam within the foam. By changing the mechanical and chemical properties of the foam 410 in combination, the flexibility of the cleaning process can be achieved by changing the on-site properties of the foam for various cleaning requirements. For example, as shown in FIG. 5A, when a small gap 224 is used, bubbles in the gap are reduced. Since the gap 224 is small, the pressure in the brush container 212 is large, so that the foam 410 exits the gap 224 at high speed. The combination of the smaller foam size and the higher foam speed increases the shear force between the foams. When the shearing force is large, the energy transmitted to the surface of the substrate 216 increases when the bubbles in the dense foam are locally rearranged.

  On the other hand, as shown in FIG. 5B, using a larger gap 224 results in larger bubbles in the gap. Because the gap 224 is large, the pressure in the brush container 212 is small, so that the foam 410 exits the gap 224 at a slower rate. The combination of the larger bubble size and lower speed facilitates removal of particles from the vias and trenches. Because different cleaning shapes provide different cleaning characteristics, the two flanges on either side of the brush container 212 may be configured to have different shapes in accordance with one embodiment of the present invention. For example, one flange 214 is configured with a small gap to cause higher shear forces, and the opposite flange 214 of the same brush container 212 removes particles from vias and trenches. It may be configured to have a larger gap. As such, in this embodiment, the brush container 212 may be configured to meet two different cleaning requirements.

  FIG. 6 is a flowchart illustrating the operation of a method for cleaning a substrate in accordance with one embodiment of the present invention. Beginning with operation 610, foam is provided to the surface of the substrate. In operation 612, the surface of the substrate is physically rubbed with the brush in the region where the surface of the brush contacts the surface of the substrate. At the same time, in operation 613, the surface of the substrate is cleaned primarily by chemical treatment with foam, in the region formed by the brush container between the region where the brush contacts the surface of the substrate and the region defined by the gap. Is done. As mentioned above, chemical treatment facilitates the removal of particles and films from the surface of the substrate by bringing gas and liquid into direct contact with the surface of the substrate by bursting bubbles in the foam. At the same time, in act 614, pressure is applied to the foam, so that in act 616 the pressurized foam is sent to form a dense foam. Specifically, the foam is fed into a gap formed by a brush container. The gap is defined by the space between the surface of the brush container (eg, flange) and the surface of the substrate. The pressure on the foam and the shape of the gap compresses the foam to form a dense foam. The local rearrangement of bubbles within the dense foam releases energy, which facilitates the removal of particles and films from the surface of the substrate.

  In short, the above-described invention provides an apparatus and method for use in cleaning a substrate. The foam container reduces the amount of foam required to cover a particular surface area of the substrate. In addition, the shape of the brush container can facilitate the removal of particles and films from the surface of the substrate by specifically directing the flow of the foam and controlling the physical properties of the foam. As a result, the brush container simultaneously allows different cleaning operations (eg, scrubbing operations, chemical treatments, foam rearrangement in a dense foam, etc.) to be performed on the surface area of the substrate.

  Although the foregoing invention has been described in some detail for better understanding, it will be apparent that certain changes and modifications may be practiced within the scope of the appended claims. Accordingly, the embodiments are to be regarded as illustrative and not restrictive, and the invention is not limited to the details shown herein, but the appended claims and equivalents. It may be modified within the range.

The simplified side view which shows the conventional system used for the cleaning of a semiconductor wafer. 1 is a perspective view showing a brush partially enclosed within a brush container, in accordance with one embodiment of the present invention. FIG. FIG. 2B is a side view showing the brush and brush container shown in FIG. 2A according to one embodiment of the present invention. 1 is a perspective view showing a substrate cleaning system according to an embodiment of the present invention. FIG. 1 is a side view of a partially enclosed brush and foam according to one embodiment of the present invention. FIG. FIG. 5 is an enlarged side view showing the gap region shown in FIG. 4 according to one embodiment of the present invention. The figure which shows another embodiment of the gap area | region shown to FIG. 5A. 5 is a flowchart illustrating the operation of a method for cleaning a substrate, in accordance with one embodiment of the present invention.

Claims (14)

A brush container used for processing a substrate,
An elongate container configured to surround the outer periphery of the brush, the elongate container being configured to be disposed above the surface of the substrate, defining both ends, and an open area along the length of the elongate container And the open area of the surface of the substrate to allow the surface of the brush to contact the surface of the substrate in the presence of the substrate. Being configured to be disposed above;
A flange along the length of the elongate container, the flange extending radially outward from an outer surface of the elongate container and defining a surface substantially parallel to the surface of the substrate in the presence of the substrate; With
A brush container, wherein a space between the surface of the flange and the surface of the substrate in the presence of the substrate defines a gap that allows the creation of a dense foam. The brush container according to claim 1,
The brush container, wherein the gap has a dimension of about 0.1 mm to about 5 mm. The brush container according to claim 1,
The brush container, wherein the flange has a conduit configured to remove liquid resulting from the collapse of a dense foam from the surface of the substrate in the presence of the substrate. The brush container according to claim 1,
The brush container, wherein the length of the brush container is configured to extend over the length of the brush. The brush container according to claim 1,
The brush container, wherein the open region extends over the length of the elongated container. A substrate cleaning system,
A first brush configured to be disposed above the surface of the substrate;
A first brush container surrounding the outer periphery of the first brush and supplying foam to the surface of the substrate;
A first drive roller;
A second drive roller;
With
The first brush container is an elongated container configured to surround the outer periphery of the first brush, and is configured to be disposed above the surface of the substrate, and has both ends defining a length. An elongate container having an open area along the length of the elongate container; and the open area is configured such that a surface of the first brush is in the presence of the first brush and the surface of the substrate is in the presence of the substrate. Being configured to be positioned above the surface of the substrate to allow contact with the surface;
A flange along the length of the elongate container, the flange extending radially outward from an outer surface of the elongate container and defining a surface substantially parallel to the surface of the substrate in the presence of the substrate; With
The space between the surface of the flange and the surface of the substrate in the presence of the substrate defines a gap that allows the creation of a dense foam;
The first and second driving rollers are configured to receive an edge portion of the substrate and to support and rotate the substrate when the substrate is disposed below the first brush. Substrate cleaning system. The substrate cleaning system according to claim 6, further comprising:
A second brush;
A second brush container surrounding the outer periphery of the second brush and supplying foam to the surface of the substrate;
With
The substrate cleaning system, wherein the second brush is disposed toward the first brush so as to receive the substrate between the first and second brushes. A method for cleaning a substrate, comprising:
Supplying foam to the surface of the substrate;
Rubbing the surface of the substrate with a brush;
Applying pressure to the foam by a brush and a brush container surrounding the outer periphery of the brush;
Sending the pressured foam into a gap defined by a space between a surface of a brush container and the surface of the substrate to produce a dense foam;
With
The method of rubbing the surface of the substrate with a brush and sending the pressured foam across the surface of the substrate facilitates removal of particles from the surface of the substrate. The method of claim 8, further comprising:
Chemically treating the surface of the substrate with the foam;
The method wherein the chemical treatment facilitates removal of the particles from the surface of the substrate. The method of claim 9, comprising:
The step of chemically treating the surface of the substrate using the foam comprises:
Rupturing bubbles in the foam to release gas and liquid onto the surface of the substrate;
The method wherein the gas and the liquid facilitate removal of the particles from the surface of the substrate. The method of claim 10, comprising:
The gas is composed of one or more of ozone (O ₃ ), oxygen (O ₂ ), hydrochloric acid (HCl), hydrofluoric acid (HF), nitrogen (N ₂ ), and argon (Ar). . The method of claim 10, comprising:
The method, wherein the liquid is composed of one or more of water (H ₂ O), deionized water (DIW), a cleaning fluid, and a surfactant. The method according to claim 8, comprising:
The method wherein the pressure on the dense foam causes a shear force on the dense foam. The method according to claim 8, comprising:
The step of applying pressure to the foam includes:
Supplying gas and liquid through a brush,
The method wherein the supply of the gas and the liquid allows for the generation of pressure on the foam.

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