POLISHING APPARATUS AND METHOD FOR POLISHING SUBSTRATE

BACKGROUND

An integrated circuit is typically formed on a substrate by the sequential deposition of conductive, semiconductive, or insulative layers on a semiconductor wafer. A variety of fabrication processes require planarization of a layer on the substrate. For example, one fabrication step involves depositing a filler layer over a non-planar surface and planarizing the filler layer. For certain applications, the filler layer is planarized until the top surface of a patterned layer is exposed. For example, a metal layer can be deposited on a patterned insulative layer to fill the trenches and holes in the insulative layer. After planarization, the remaining portions of the metal in the trenches and holes of the patterned layer form vias, plugs, and lines to provide conductive paths between thin film circuits on the substrate. As another example, a dielectric layer can be deposited over a patterned conductive layer, and then planarized to enable subsequent photolithographic steps.

Chemical mechanical polishing (CMP) is one accepted method of planarization. This planarization method typically requires that the substrate be mounted on a carrier head. The exposed surface of the substrate is typically placed against a rotating polishing pad. The carrier head provides a controllable load on the substrate to push it against the polishing pad. A polishing slurry with abrasive particles is typically supplied to the surface of the polishing pad.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is noted that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

FIG. 1 illustrates a schematic view of a polishing apparatus in accordance with some embodiments.

FIG. 2 illustrates a cross-sectional view of a mixed liquid feeder of a polishing apparatus in accordance with some embodiments.

FIG. 3 illustrates a cross-sectional view of mixing chamber of a polishing apparatus in accordance with some embodiments.

FIG. 4 illustrates a cross-sectional view of mixing chamber of a polishing apparatus in accordance with some embodiments.

FIG. 5 to FIG. 7 illustrate a partial cross-sectional view of intermediate stages in the manufacturing of a semiconductor wafer according to some exemplary embodiments of the present disclosure.

FIG. 8 illustrates a partial schematic view of a polishing apparatus in accordance with some embodiments.

FIG. 9 illustrates a schematic view of a sensing device of a polishing apparatus in accordance with some embodiments.

FIG. 10 illustrates a flow chart of a method for polishing a substrate in accordance with some embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

Implementations of the present disclosure generally relate to planarization of surfaces on a substrate and on layers formed on the substrate, including an apparatus for providing mixed polishing liquid during polishing, and methods of using the same. Certain details are set forth in the following description and in FIG. 1 to FIG. 10 to provide a thorough understanding of various implementations of the disclosure. Other details describing well-known structures and systems often associated with substrate polishing are not set forth in the following disclosure to avoid unnecessarily obscuring the description of the various implementations.

Many of the details, dimensions, angles and other features shown in the Figures are merely illustrative of particular implementations. Accordingly, other implementations can have other details, components, dimensions, angles and features without departing from the spirit or scope of the present disclosure. In addition, further implementations of the disclosure can be practiced without several of the details described below.

FIG. 1 illustrates a schematic view of a polishing apparatus in accordance with some embodiments. Referring to FIG. 1, a polishing apparatus 100 is configured to perform a polishing process, such as a chemical-mechanical planarization (CMP) process. The polishing apparatus 100 may be a stand-alone apparatus or part of a larger processing system. In some embodiments, the polishing apparatus 100 includes a polishing head 106, a platen 108, a first liquid source 130, a second liquid source 140, and a mixed liquid feeder 150 (such as a slurry feeder). In some embodiments, the polishing apparatus 100 may further include a conditioning device 110 disposed over the platen 108 and configured for conditioning the polishing pad 104 supported by the platen 108. The platen 108, the conditioning device 110, and the mixed liquid feeder 150 may be mounted to a base of the polishing apparatus 100.

In accordance with some embodiments of the disclosure, the platen 108 includes a polishing pad 104 having a polishing surface 120 for polishing a substrate 122 held by the polishing head 106. The platen 108 is configured to be rotated by a motor (not shown). The polishing pad 104 is rotated relative to the substrate 122 retained in the polishing head 106 during processing. As such, terms such as upstream, downstream, in front, behind, before, and after are generally interpreted relative to the motion or direction of the platen 108 and the polishing pad 104 supported thereon, as appropriate. In some implementations where the platen 108 rotates along a rotational movement R1 (for example, but not limited thereto, counterclockwise direction as shown in FIG. 1), the mixed liquid feeder 150 may be located upstream of the polishing head 106.

In accordance with some embodiments of the disclosure, the polishing head 106 is disposed over the platen 108 and configured to hold the substrate 122. The polishing pad 104 and the polishing head 106 of the polishing apparatus 100 may be used to planarize a process surface 124 of the substrate 122. The process surface 124 of the substrate 122 may be planarized by use of physical contact of the process surface 124 of the substrate 122 against the polishing pad 104 and by use of relative motion. The planarization removes unwanted surface topography and surface defects in preparation for subsequent processes where layers of materials are sequentially deposited on and removed from the process surface 124 of the substrate 122. The substrate 122 may be, for example, a semiconductor wafer. During planarization, the substrate 122 may be mounted in the polishing head 106, and the process surface 124 of the substrate 122 is positioned by a carrier assembly 128 of the polishing apparatus 100 to contact the polishing pad 104. The carrier assembly 128 provides a controlled force F to the substrate 122 mounted in the polishing head 106 to urge the process surface 124 of the substrate 122 against the polishing surface 120 of the polishing pad 104. In this manner, contact is created between the substrate 122 and the polishing pad 104.

Removal of the undesirable topography and surface defects is also accomplished by relative rotational movement between the polishing pad 104 and the substrate 122 in the presence of the mixed polishing liquid, such as a polishing fluid or slurry, therebetween. The platen 108 of the polishing apparatus 100 supports the polishing pad 104 and provides rotational movement R1 to the polishing pad 104 about an axis of rotation A1. The platen 108 may be rotated by a motor (not shown) of the polishing apparatus 100. The carrier assembly 128 may also provide rotational movement R2 about an axis of rotation A2 to the substrate 122 mounted within the polishing head 106. Within the environment of this relative motion is the mixed polishing liquid. The polishing surface 120 of the polishing pad 104 may be generally planar, but may also include grooves (not shown) which may improve the performance of the polishing pad 104 by distributing the mixed polishing liquid which is applied to the polishing surface 120 by use of the mixed liquid feeder 150. In general, the mixed polishing liquid may include chemical composition, typically mixed with abrasive, for selective removal of material from the process surface 124 of the substrate 122. The material removed from the process surface 124 may include conductive materials (e.g., metallic materials), dielectric materials, polymer materials, composite materials, metal nitride materials or combinations thereof. The mixed liquid feeder 150 may dispense the mixed polishing liquid on the polishing pad 104 before, during, or after relative motion. As one skilled in the art would understand, the polishing pad 104 may include features that would retain the polishing media, e.g. pores and/or polishing pad grooves found in the polishing pad 104. The mixed polishing liquid, characteristics of the polishing pad 104, the force F, and the rotational movements R1, R2 create frictional forces and abrasive forces at the process surface 124 of the substrate 122.

The polishing apparatus 100 may include other components to enable consistent polishing. With continued reference to FIG. 1, during planarization the frictional forces and abrasive forces may also cause wear to the polishing pad 104, which may necessitate periodic roughening (conditioning) to maintain the effectiveness of the polishing pad 104 and ensures consistent polishing rates. In this regard, the polishing apparatus 100 may optionally include the conditioning device 110 with a conditioning head 160 mounted to one end of a pivot arm 162, and a pad conditioner 164, such as a pad embedded with diamond crystals, mounted to the underside of the conditioning head 160. The pivot arm 162 may be operatively connected to the platen 108, and may maintain the pad conditioner 164 against the polishing pad 104 as the pivot arm 162 sweeps back and forth across the radius of the polishing pad 104 in an arcing motion to condition the polishing pad 104. In this manner, the polishing pad 104 is conditioned to provide consistent polishing rates.

Referring to FIG. 1, in some implementations, the polishing head 106 is disposed in a process chamber at a first location, the conditioning device 110 is disposed in the process chamber at a second location, and the mixed liquid feeder 150 is disposed in the process chamber at a third location. In the present embodiment, the second location is disposed radially about a central axis A1 of the platen 108 and located between the first location and the third location, but the disclosure is not limited thereto.

FIG. 2 illustrates a cross-sectional view of a mixed liquid feeder of a polishing apparatus in accordance with some embodiments. Referring to FIG. 1 and FIG. 2, in some embodiments, the mixed liquid feeder 150 is coupled to the first liquid source 130 and the second liquid source 140. The first liquid source 130 stores first polishing liquid 132 containing a first proportion of a component reacting with a material on the substrate 122. The second liquid source 140 is configured to provide second polishing liquid 142 containing a second proportion of the component less than the first proportion of the component in the first polishing liquid 132. In other words, the amount of the component contained in the second polishing liquid 142 is less than the amount of the component contained in the first polishing liquid 132. The mixed liquid feeder 150 is configured to mix the first polishing liquid 132 and the second polishing liquid 142 into a mixed polishing liquid 135 and feed the mixed polishing liquid 135 to the polishing surface 120 of the polishing pad 104. Thereby, the concentration or amount of the component in the mixed polishing liquid 135 can be controlled more precisely by adjusting the amount of the first polishing liquid 132 and the amount of the second polishing liquid 142 provided to the mixed liquid feeder 150.

For example, the first liquid source 130 and the second liquid source 140 may each include a polishing liquid storage tank, a polishing liquid supply tube and a pump. The polishing liquid storage tank is configured to store polishing liquid. One end of the polishing liquid supply tube is positioned in the polishing liquid storage tank, and the other end of the polishing liquid supply tube is connected to the mixed liquid feeder 150. The pump is placed somewhere along the polishing liquid supply tube, so that the pump pumps the polishing liquid from the polishing liquid storage tank into the mixed liquid feeder 150.

Referring to FIG. 2, the mixed liquid feeder 150 includes a mixing chamber 151 that is coupled to the first liquid source 130 and the second liquid source 140, such that the first polishing liquid 132 provided by the first liquid source 130 and the second polishing liquid 142 provided by the second liquid source 140 can be mixed in the mixing chamber 151. The mixing chamber 151 includes a first inlet 154 coupled the first liquid source 130 for introducing the first polishing liquid 132 into the mixing chamber 151 and a second inlet 156 coupled to the second liquid source 140 for introducing the second polishing liquid 142 into the mixing chamber 151, and an outlet 124 from which the mixed polishing liquid 135 is discharged.

Referring to FIG. 2, in the embodiment, the mixing chamber 151 may include a first chamber 1511 which is a swirling flow generating chamber for generating a swirling flow, and a second chamber 1512 which is a narrowing chamber for concentrating the swirling flow in an axial direction. An included angle ranging from 10° to 180° may be included between the first inlet 154 and the second inlet 156 to respectively provide the first polishing liquid 132 and the second polishing liquid 142 in an inclined manner with respect to the gravity, so as to create the swirling flow within the mixing chamber 151. The first chamber 1511 in the present example has a cylindrical outer shape and a columnar inner space. The second chamber 1512 in the present example has a funnel outer shape and a conical internal space coaxial with the internal space of the first chamber 1511.

FIG. 3 illustrates a cross-sectional view of mixing chamber of a polishing apparatus in accordance with some embodiments. Referring to FIG. 1 and FIG. 3, in the embodiment, the mixing chamber 151a may include a swirling passage 155 as shown in FIG. 3. One end of the swirling passage 155 is coupled to the first inlet 154 and the second inlet 156 for receiving the first polishing liquid 132 and the second polishing liquid 142 from the first liquid source 130 and the second liquid source 140 respectively. Another end of the swirling passage 155 is coupled to the outlet 152 from which the mixed polishing liquid 135 is discharged. Accordingly, the first polishing liquid 132 and the second polishing liquid 142 can be mixed in the mixing chamber by flowing along the swirling direction guided by the swirling passage 155.

FIG. 4 illustrates a cross-sectional view of mixing chamber of a polishing apparatus in accordance with some embodiments. Referring to FIG. 1 and FIG. 4, in the embodiment, the mixing chamber 151b may include a plurality of flow generating protrusions 153 on the inner surface of the mixing chamber 151b as shown in FIG. 4. Accordingly, the first polishing liquid 132 and the second polishing liquid 142 flow through the first inlet and the second inlet respectively into the mixing chamber 151b and the flow generating protrusions 153 disturbed the flowing direction of the first polishing liquid 132 and the second polishing liquid 142, so as to facilitate the mixing of the first polishing liquid 132 and the second polishing liquid 142. Then, the mixed polishing liquid 135 can be well mixed and discharged through the outlet of the mixing chamber 151b. In other words, the first polishing liquid 132 and the second polishing liquid 142 can be mixed in the mixing chamber by flowing along the swirling direction guided by the flow generating protrusions 153 in the mixing chamber 151b. It is noted that the disclosure merely illustrates some of the possible configurations of the mixing chamber, but the structure and configuration of the mixing chamber for mixing the polishing liquid therein is not limited thereto.

FIG. 5 to FIG. 7 illustrate a partial cross-sectional view of intermediate stages in the manufacturing of a substrate according to some exemplary embodiments of the present disclosure. FIG. 8 illustrates a partial schematic view of a polishing apparatus in accordance with some embodiments. Referring to FIG. 5 and FIG. 8, in some embodiments, the substrate 122 is placed in contact with the polishing pad 104 for the polishing process. The substrate 122 may be a semiconductor wafer, which includes a semiconductor substrate 1223 and a conductive layer 1221 composed of a material of metal such as tungsten, molybdenum, ruthenium, or copper, for example. In the embodiment, the conductive layer 1221 may be disposed over the semiconductor substrate 1223 and an interlayer 1222 such as an etch stop layer or barrier layer may be interposed between the conductive layer 1221 and the semiconductor substrate 1223. To be more specific, the semiconductor substrate 1223 may include a plurality of trenches OP1 etched into the semiconductor substrate 1223. The interlayer 1222180 may be formed across the semiconductor substrate 1223 conforming to the surface topography of the etched trenches OP1. The conductive layer 1221 may cover and fill the trenches OP1 of the semiconductor substrate 1223. Accordingly, the polishing process may be performed over more than one material, so the amount of some specific components in the polishing liquid that react with some specific materials on the substrate may be adjusted as encountering different materials during polishing process. The following description in connection with FIG. 5 to FIG. 7 and FIG. 10 describes examples of polishing method on how the substrate 122 with more than one material is planarized or provided with a prescribed surface smoothness.

In accordance with some embodiments of the disclosure, the method for polishing the substrate 122 may include the following steps. Firstly, referring to FIG. 1 and FIG. 10, at step S110, the substrate 122 is provided over the polishing pad 104 of the platen 108 of the polishing apparatus 100. In some embodiments, the substrate 122 is held by the polishing head 106 above the polishing pad 104. The substrate 122 includes at least one material such as conductive layer 1221 and interlayer 1222 over the semiconductor substrate 1223.

Then, referring to FIG. 8 and FIG. 10, the substrate 122 is pressed against the polishing pad 104 by the polishing head 106. In detail, the polishing head 106 provides a controllable pressure to the substrate 122 against the polishing pad 104. In some embodiments, the polishing apparatus 100 further includes at least one sensing device 103 configured to detect a presence of the material on the substrate 122, and a controller 105 at least coupled to the sensing device 103 and the mixed liquid feeder 150. The controller 105 is provided to facilitate control and integration of the systems of the polishing apparatus 100. The controller 105 may include a central processing unit (CPU), a memory, and support circuits. The controller 105 is coupled with the various components of the polishing apparatus 100 to facilitate control of the polishing process, mixed polishing liquid delivery, rinse liquid delivery, etc. Accordingly, at step S120, before the polishing process is performed, a presence of the material on the substrate 122 is detected by the sensing device 103 and sensing a corresponding sensing signal to the controller 105. Then, at step S130, the controller 105 determined whether the presence of the material is less than a predetermined amount such as a thickness of the material, or a proportion/coverage of the material, etc., and controls the amount of the first polishing liquid and the amount of the second polishing liquid provided to the mixed liquid feeder 150 respectively to provide the mixed polishing liquid with desired composition and centration according to the presence of the material. For example, the controller 105 determines whether the coverage of the material is less than about 90%, or the thickness of the material is less than about 100 nm.

For example, referring to FIG. 5 and FIG. 8, in the embodiment, the uppermost layer that is firstly subjected to polishing process is the conductive layer 1221, which is made of metal material. Therefore, in the embodiment, the presence of metal on the semiconductor substrate 1223 is detected to obtain a thickness of the conductive layer 1221, or the proportion of the conductive layer 1221 on the surface to be polished. For example, in the stage shown in FIG. 5, the conductive layer 1221 completely covers the surface to be polished, so the proportion (coverage) of the conductive layer 1221 on the surface to be polished is 100%. That is the presence of the material (e.g., metal) is detected to be greater than or substantially equal to the predetermined amount. Accordingly, step S140 is performed, the controller 105 determines the first amount of the first polishing liquid provided to the mixed liquid feeder 150 is less than or substantially equal to the second amount of the second polishing liquid provided to the mixed liquid feeder 150.

In general, the polishing liquid may include components that react with the material to be removed such as abrasive causing material removal by micro-chipping, a corrosion inhibitor for reducing a corrosion rate of the material, a corrosion promoter for increasing a corrosion rate of the material. The polishing liquid may further include other general components such as bio-agent, PH buffer, deionized water, or the like. The bio-agent may include benzotriazole (BTA), sodium azide, and sodium sulfite, or the like. PH buffer may include acid, alkali base material, or the like.

In some embodiments, the first polishing liquid containing a first proportion of the component reacting with the material to be polished and second polishing liquid containing a second proportion of the component less than the first proportion. That is, the component reacting with the material to be polished in the second polishing liquid is less than such component in the first polishing liquid, so by adjusting the amount of the first polishing liquid and the second polishing liquid provided to be mixed in the mixed liquid feeder 150, the mount (concentration) of such component in the mixed polishing liquid 135 can be well controlled. In the embodiment of the material to be polished being metal material such as tungsten, molybdenum, ruthenium, or copper, etc., the component reacting with such metal material includes corrosion promoter for speeding up metal corrosion rate or corrosion inhibitor for slowing down metal corrosion rate. In the present embodiment, the component to be controlled is corrosion inhibitor such as organic acid, amine, surfactant, polymer, or the like. In one embodiments, the concentration of the component (e.g., corrosion inhibitor) in the first polishing liquid is ten times more than the concentration of the component in the second polishing liquid. In other embodiments, the second polishing liquid may contain no component (e.g., corrosion inhibitor) reacting with the material to be polished, while the first polishing liquid contains such component with certain amount. In other embodiments, the component reacting with the metal material to be polished may be corrosion promoter, which includes oxidizer, Fenton chemical, chelator, organic acids, or the like.

In the embodiment of the component being corrosion inhibitor, the proportion of the first polishing liquid (having higher concentration of the corrosion inhibitor) and the proportion of the second polishing liquid (having lower concentration of the corrosion inhibitor) provided to the mixed liquid feeder 150 are respectively about 10% and 90%, so the corrosion inhibitor for slowing down metal corrosion rate contains in the mixed polishing liquid 135 is relatively low, so the polishing/corrosion of the metal can be performed more efficiently. On the contrary, in the embodiment of the component being corrosion promoter, the proportion of the first polishing liquid and the proportion of the second polishing liquid provided to the mixed liquid feeder 150 are respectively about 90% and 10%, so the corrosion promoter for speeding up metal corrosion rate contains in the mixed polishing liquid 135 is relatively high, so the polishing/corrosion of the metal can be performed more efficiently.

In other embodiments, when the material to be polished is dielectric material, the concentration of the component to be controlled in the mixed polishing liquid 135 may include abrasive causing material removal by micro-chipping and corrosion inhibitor for slowing down dielectric corrosion rate. The abrasive includes particle of ceria, silica, alumina, diamond, zirconia, titanium, or the like. The corrosion inhibitor for slowing down dielectric corrosion rate includes organic acid, amine, surfactant, polymer, or the like. Accordingly, in the embodiment of the component being abrasive, the proportion of the first polishing liquid (having higher concentration of the abrasive) and the proportion of the second polishing liquid (having lower concentration of the abrasive) provided to the mixed liquid feeder 150 are respectively about 90% and 10%, so the abrasive causing material removal by micro-chipping in the mixed polishing liquid 135 is relatively high, so the polishing of the dielectric material can be performed more efficiently. On the contrary, in the embodiment of the component being corrosion promoter, the proportion of the first polishing liquid and the proportion of the second polishing liquid provided to the mixed liquid feeder 150 are respectively about 10% and 90%, so the corrosion inhibitor for slowing down dielectric corrosion rate contains in the mixed polishing liquid 135 is relatively low, so the polishing/corrosion of the dielectric material can be performed more efficiently.

Accordingly, the first polishing liquid and the second polishing liquid are provided to the mixed liquid feeder 150 with individually controlled proportions to mix the first polishing liquid and the second polishing liquid into the mixed polishing liquid 135. Then, at step S160, the polishing process is performed by the polishing pad 104 while providing the mixed polishing liquid 135 to the polishing surface of the polishing pad 104 to remove at least a portion of the material (e.g., the conductive layer 1221). An external driving force moves the polishing pad 104 relative to the substrate 122. Thus, the polishing apparatus 100 creates polishing or rubbing movement between the uppermost surface (e.g., the top surface of the conductive layer 1221) of the substrate 122 and the polishing pad 104 while dispersing the mixed polishing liquid 135 to affect both chemical activity and mechanical activity.

Then, referring to FIG. 6 and FIG. 8, during the polishing process, the sensing device 10 may continuingly or periodically detect the presence of the material to determine whether the presence of the material is less than a predetermined amount (i.e., going back to step S120 and S130), for example, the coverage of the material (e.g., conductive layer 1221) is less than about 90%, or the thickness T1 of the material is less than about 100 nm. When the controller 105 determines the presence of the material is less than a predetermined amount, for example, the thickness T1 of the material is less than about 100 nm, step S150 is performed, the controller 105 determines the first amount of the first polishing liquid (having higher concentration of the component reacting with the material) provided to the mixed liquid feeder 150 is greater than the second amount of the second polishing liquid (having higher concentration of the component reacting with the material) provided to the mixed liquid feeder 150.

In the embodiment of the component being corrosion inhibitor, the proportion of the first polishing liquid (having higher concentration of the corrosion inhibitor) and the proportion of the second polishing liquid (having lower concentration of the corrosion inhibitor) provided to the mixed liquid feeder 150 are respectively about 25% and 75%, so the corrosion inhibitor for slowing down metal corrosion rate contains in the mixed polishing liquid 135 is higher than the polishing stage shown in FIG. 5, so the polishing/corrosion rate of the metal is slower compared the polishing stage shown in FIG. 5. On the contrary, in the embodiment of the component being corrosion promoter, the proportion of the first polishing liquid and the proportion of the second polishing liquid provided to the mixed liquid feeder 150 are respectively about 75% and 25%, so the corrosion promoter for speeding up metal corrosion rate contains in the mixed polishing liquid 135 is lower than the polishing stage shown in FIG. 5, so the polishing/corrosion rate of the metal is slower compared the polishing stage shown in FIG. 5.

In other embodiments, in the embodiment of the material to be polished is dielectric material and the component being abrasive, the proportion of the first polishing liquid (having higher concentration of the abrasive) and the proportion of the second polishing liquid (having lower concentration of the abrasive) provided to the mixed liquid feeder 150 are respectively about 75 and 25%, so the abrasive causing material removal by micro-chipping in the mixed polishing liquid 135 lower than the polishing stage shown in FIG. 5, so the polishing/corrosion rate of the metal is slower compared the polishing stage shown in FIG. 5. On the contrary, in the embodiment of the material to be polished is dielectric material and the component being corrosion inhibitor, the proportion of the first polishing liquid and the proportion of the second polishing liquid provided to the mixed liquid feeder 150 are respectively about 25% and 75%, so the corrosion inhibitor for slowing down dielectric corrosion rate contains in the mixed polishing liquid 135 is higher than the polishing stage shown in FIG. 5, so the polishing/corrosion rate of the metal is slower compared the polishing stage shown in FIG. 5.

Then, referring to FIG. 7 and FIG. 8, continuing with the polishing process, when the polishing process encounters the interface of the material to be polished (i.e., the conductive layer 1221) and the material underneath (i.e., interlayer 1222 or the semiconductor substrate 1223), the sensing device 103 may continuingly or periodically detect the presence of the material to determine whether the presence of the material is less than a predetermined amount, for example, the coverage of the material (e.g., conductive layer 1221) is less than about 90%, or the thickness T1 of the material is less than about 100 nm. When the controller 105 determines the coverage of the material (e.g., conductive layer 1221) is less than about 90%, which means the polishing process encounters the interface between materials, the controller 105 determines the first amount of the first polishing liquid (having higher concentration of the component reacting with the material) provided to the mixed liquid feeder 150 is even greater than the second amount of the second polishing liquid (having higher concentration of the component reacting with the material) provided to the mixed liquid feeder 150.

For example, in the embodiment of the component being corrosion inhibitor, the proportion of the first polishing liquid (having higher concentration of the corrosion inhibitor) and the proportion of the second polishing liquid (having lower concentration of the corrosion inhibitor) provided to the mixed liquid feeder 150 are respectively about 100% and 0%, which means no second polishing liquid is provided. Accordingly, the corrosion inhibitor for slowing down metal corrosion rate contains in the mixed polishing liquid 135 is much higher than the polishing stage shown in FIG. 6, so the polishing/corrosion rate of the metal is much slower compared the polishing stage shown in FIG. 6, so as to avoid corrosion recesses occurs on the conductive layer 1221. On the contrary, in the embodiment of the component being corrosion promoter, the proportion of the first polishing liquid and the proportion of the second polishing liquid provided to the mixed liquid feeder 150 are respectively about 0% and 100%, so the corrosion promoter for speeding up metal corrosion rate contains in the mixed polishing liquid 135 is much lower than the polishing stage shown in FIG. 6, so the polishing/corrosion rate of the metal is slower compared the polishing stage shown in FIG. 6.

In other embodiments, in the embodiment of the material to be polished is dielectric material and the component being corrosion inhibitor, the proportion of the first polishing liquid and the proportion of the second polishing liquid provided to the mixed liquid feeder 150 are respectively about 100% and 0%, so the corrosion inhibitor for slowing down dielectric corrosion rate contains in the mixed polishing liquid 135 is much higher than the polishing stage shown in FIG. 6, so the polishing/corrosion rate of the metal is much slower compared the polishing stage shown in FIG. 6.

Accordingly, the first polishing liquid and the second polishing liquid are provided to the mixed liquid feeder 150 with individually controlled proportions to mix the first polishing liquid and the second polishing liquid into the mixed polishing liquid 135. Then, at step S160, the polishing process is performed by the polishing pad 104 while providing the mixed polishing liquid 135 to the polishing surface of the polishing pad 104 to continuingly perform the polishing process. Thereby, the concentration of the components reacting with the material to be polished in the mixed polishing liquid 135 can be well controlled and adjusted according to different stages of the polishing process, such that polishing and corrosion on the surface of the substrate can perform more evenly, especially when there are more than two different materials on the surface of the substrate. In other embodiments, more than two polishing liquid with various component concentration may be provided to the mixed liquid feeder 150 to provide the mixed polishing liquid with desired component concentration.

FIG. 9 illustrates a schematic view of a sensing device of a polishing apparatus in accordance with some embodiments. In some embodiments, the sensing device 103 may include an eddy current monitoring device, a dielectric motor, or an optical sensing device. Referring to FIG. 9, in the embodiment, the sensing device 103 is the eddy current monitoring device for inducing eddy currents in the conductive (metal) layer 1221 and measure changes in eddy currents as the conductive layer 1221 is removed. To be more specific. The eddy current monitoring device may include a magnetic core 1031 disposed in the polish pad 104 so as to rotate with the polish pad 104, a drive coil 1032 wound around a part of the magnetic core 1031, and a detection coil wound around a second part of the magnetic core 1031. The eddy current monitoring device may further include an oscillator connected to the drive coil 1032, and a capacitor coupled in parallel with the detection coil. In operation, the oscillator drives the drive coil 1032 to generate an oscillating magnetic field 1035 that extends from the body of the magnetic core 1031 and enters the gap between its two magnetic poles 1033, 1034. At least a portion of this magnetic field 1035 extends through the thin portion of the polishing pad 104 and enters the substrate 122. If the conductive layer 1221 is on the substrate 122, the oscillating magnetic field 1035 generates an eddy current in the conductive layer 1221. The eddy current causes the conductive layer 1221 to act as an impedance source in parallel with the detection coil and the capacitor. As the thickness of the conductive layer 1221 changes, the impedance changes, resulting in a change in factor of the detection mechanism. Accordingly, the eddy current sensor detects a change in the intensity of the eddy current, and thus detects a change in the thickness of the conductive layer 1221. Thereby, the eddy current monitoring device can be used to detect the remaining thickness of the conductive layer 1221 during the polishing process, so that the polishing apparatus can change the slurry composition accordingly.

In other embodiments, the sensing device may include an optical sensing device disposed in the polishing pad 104 along with or in substitute of the eddy current monitoring device. The optical sensing device may include a light source and a detector. The light source generates a light beam that impinges on the exposed surface of the substrate 122 so as to detect reflected light of the light beam from the substrate 122. In other words, the eddy current monitoring device is configured to determine whether the conductive layer 1221 has reached a predetermined thickness, while the optical sensing device is configured to determine when the lower layer is exposed. In other embodiments, the sensing device may include a dielectric motor, which is also known as motor torque. The dielectric motor is configured for identifying the electric conductivity and permittivity of dielectric materials so as to detect the presence of the dielectric material.

Based on the above discussions, it can be seen that the present disclosure offers various advantages. It is understood, however, that not all advantages are necessarily discussed herein, and other embodiments may offer different advantages, and that no particular advantage is required for all embodiments.

In accordance with some embodiments of the disclosure, a polishing apparatus includes a platen, a polishing head, a first liquid source, a second liquid source, and a mixed liquid feeder. The platen includes a polishing pad having a polishing surface for polishing a substrate. The polishing head is disposed over the platen and configured to hold the substrate. The first liquid source is configured to provide first polishing liquid containing a first proportion of a component reacting with a material on the substrate. The second liquid source is configured to provide second polishing liquid containing a second proportion of the component less than the first proportion. The mixed liquid feeder is coupled to the first liquid source and the second liquid source, wherein the mixed liquid feeder is configured to mix the first polishing liquid and the second polishing liquid into a mixed polishing liquid and feed the mixed polishing liquid to the polishing surface of the polishing pad. In an embodiment, the mixed liquid feeder comprises a mixing chamber coupled to the first liquid source and the second liquid source for mixing the first polishing liquid and the second polishing liquid therein and comprising an outlet from which the mixed polishing liquid is discharged. In an embodiment, the mixing chamber further comprises a first inlet coupled the first liquid source for introducing the first polishing liquid into the mixing chamber and a second inlet coupled to the second liquid source for introducing the second polishing liquid into the mixing chamber. In an embodiment, the polishing apparatus further includes a conditioning device disposed over the platen and configured for conditioning the polishing pad. In an embodiment, the component comprises abrasive, a corrosion inhibitor for reducing a corrosion rate of the material, a corrosion promoter for increasing a corrosion rate of the material. In an embodiment, the polishing apparatus further includes a sensing device configured to detect a presence of the material on the substrate. In an embodiment, the polishing apparatus further includes a controller coupled to the sensing device and the mixed liquid feeder, wherein the controller controls the mixed liquid feeder to mix the first polishing liquid with a first amount and the second polishing liquid with a second amount less than the first amount when the sensing device detects that the presence of the material is less than a predetermined amount. In an embodiment, the component comprises a corrosion inhibitor for reducing a corrosion rate of the material. In an embodiment, the sensing device comprises an eddy current monitoring device, a dielectric motor, or an optical sensing device.

In accordance with some embodiments of the disclosure, a method for polishing a substrate includes the following steps. The substrate is provided over a platen of a polishing apparatus, wherein the substrate comprises a material over a semiconductor substrate. The substrate is pressed against a polishing pad of the platen. A polishing process is performed by the polishing pad while providing a mixed polishing liquid to remove a portion of the material, wherein the mixed polishing liquid is a mixture of first polishing liquid containing a first proportion of a component reacting with the material and second polishing liquid containing a second proportion of the component less than the first proportion. In an embodiment, the method further includes detecting a presence of the material before the mixed polishing liquid is provided; and mixing a first polishing liquid with a first amount and a second polishing liquid with a second amount, wherein the first amount and the second amount is determined according to the presence of the material. In an embodiment, when the presence of the material is detected to be less than a predetermined amount, the first amount is determined to be greater than the second amount. In an embodiment, when the presence of the material is detected to be greater than or substantially equal to a predetermined amount, the first amount is determined to be less than or substantially equal to the second amount. In an embodiment, the component comprises abrasive or corrosion inhibitor when the material comprises dielectric material. In an embodiment, the component comprises corrosion promoter or corrosion inhibitor when the material comprises tungsten, molybdenum, ruthenium, or copper. In an embodiment, the first proportion of the component is at least ten times more than the second proportion of the component.

In accordance with some embodiments of the disclosure, a method for polishing a substrate includes the following steps. The substrate is provided over a polishing pad of a polishing apparatus, wherein the substrate comprises a material. The substrate is pressed against the polishing pad by a polishing head. A polishing process is performed by the polishing pad while providing a mixed polishing liquid to remove a portion of the material, wherein the mixed polishing liquid is a mixture of first polishing liquid containing a first proportion of corrosion inhibitor and second polishing liquid containing a second proportion of the corrosion inhibitor less than the first proportion. In an embodiment, the method further includes detecting a presence of the material before the mixed polishing liquid is provided; and mixing the first polishing liquid with a first amount and the second polishing liquid with a second amount, wherein the first amount and the second amount is determined according to the presence of the material. In an embodiment, when the presence of the material is detected to be less than a predetermined amount, the first amount is determined to be greater than the second amount. In an embodiment, when the presence of the material is detected to be greater than or substantially equal to a predetermined amount, the first amount is determined to be less than or substantially equal to the second amount.

The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.

POLISHING APPARATUS AND METHOD FOR POLISHING SUBSTRATE

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