Patent Application
20240308027
This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2023-039030, filed on Mar. 13, 2023, the entire contents of which are incorporated herein by reference.
The embodiments of the present invention relate to a polishing apparatus, a polishing method, and a semiconductor device manufacturing method.
In a process of manufacturing a semiconductor device, polishing is performed by chemical mechanical polishing (CMP) or the like in some cases. However, planarization is difficult in some cases depending on the pattern of wiring or the like in the semiconductor device.
Embodiments will now be explained with reference to the accompanying drawings. The present invention is not limited to the embodiments. It should be noted that the drawings are schematic or conceptual, and the relationship between the thickness and the width in each element and the ratio among the dimensions of elements do not necessarily match the actual ones. Even if two or more drawings show the same portion, the dimensions and the ratio of the portion may differ in each drawing. In the present specification and the drawings, elements identical to those described in the foregoing drawings are denoted by like reference characters and detailed explanations thereof are omitted as appropriate.
A polishing apparatus according to the present embodiment includes a head, a polishing table, a rotation table, a particle supplier, and one chamber. The head holds an object. The polishing table polishes a polishing target surface of the polishing target object. The rotation table is capable of contacting the polishing target surface. The particle supplier supplies slurry containing particles onto the rotation table so that the particles are fixed onto at least part of the polishing target surface, while the polishing target surface is contacting the rotation table. The one chamber houses the polishing table and the rotation table.
The polishing apparatus 1 includes, for example, a chemical mechanical polishing (CMP) device. The polishing apparatus 1 includes a chamber 10, a transfer device 20, a polishing table 30, a slurry supplier 40, an depositing table (rotation table) 50, a particle supplier 60, a gas supplier 70, a pad conditioner 80, and a controller 90.
The chamber 10 houses the transfer device 20, the polishing table 30, the slurry supplier 40, the depositing table 50, the particle supplier 60, the gas supplier 70, and the pad conditioner 80. In the example illustrated in
The wafer W is conveyed into the chamber 10 and subjected to processing by the polishing apparatus 1. The processed wafer W is conveyed out of the chamber 10 for processing in the next process, rinse, or the like.
The transfer device 20 conveys the wafer W. Transfer device is, for example, a conveyer. The transfer device 20 moves the wafer W between the polishing table 30 and the depositing table 50.
The polishing table 30 polishes a polishing target surface S (refer to
The slurry supplier 40 supplies slurry (polish) onto the polishing table 30. The slurry includes, for example, liquid chemical containing a chemical component or the like that reforms the polishing target object, abrasive particles for mechanically polishing the polishing target object, and/or a viscosity adjuster (polymer). The slurry supplier is, for example, a nozzle or a pipe.
The depositing table 50 is a rotation table that is rotatable. The depositing table 50 is disposed adjacent to the polishing table 30. The depositing table 50 is capable of contacting the polishing target surface S of the wafer W. The depositing table 50 fixes (accumulates) particles P onto the polishing target surface S of the wafer W. Processing of the wafer W by the depositing table 50 is referred to as deposition processing in the following description.
The particle supplier 60 supplies slurry L onto the depositing table 50 as described later. The slurry L contains the particles P and is liquid for fixing (accumulating) the particles P onto at least part of the polishing target surface S of the wafer W. More specifically, at least part of the polishing target surface S includes a stepped portion which has a level difference, a concave portion, or the like. With the particles P, the stepped portion or concave portion of the polishing target surface S can be protected during polishing by the polishing table 30. As a result, the stepped portion or the concave portion is less likely to be polished than a convex part of the polishing target surface S, and polishing can be performed flatter. In the example illustrated in
The gas supplier 70 supplies gas onto the depositing table 50.
The pad conditioner 80 includes two pad conditioners 81 and 82. The pad conditioners 81 and 82 perform dressing (conditioning) of pads (a polishing pad 32 and an depositing pad 52) of the polishing table and the depositing table 50, respectively.
The controller 90 controls the particle supplier 60. More specifically, the controller 90 controls the particle supplier 60 based on change of drive current detected by a drive current detector 211 (refer to
The transfer device 20 includes a polishing head 21, a swing arm 22, and a swing shaft 23.
The polishing head (holder) 21 holds the wafer W. The polishing head 21 is rotatably provided. The polishing head 21 can adsorb the wafer W onto the back surface of the polishing target surface S. The polishing head 21 can press the wafer W against the polishing table 30 and the depositing table 50.
The polishing head 21 includes the drive current detector 211. The drive current detector 211 detects, for example, drive current flowing through a rotational drive mechanism (motor; not illustrated) of the polishing head 21. The drive current detector 211 transmits the detected drive current to the controller 90. The detection result of the drive current is used to calculate a load (torque) on the rotational drive mechanism by the controller 90.
The swing arm 22 is coupled to the polishing head 21.
The swing shaft 23 swings the swing arm 22 about an axis illustrated with a dashed and single-dotted line. Accordingly, the wafer W can be conveyed.
The polishing table 30 includes a rotary surface plate 31 and the polishing pad 32.
The rotary surface plate 31 is rotatably provided. The rotary surface plate 31 rotates, for example, in a rotary scheme. The rotary surface plate 31 is also referred to as a platen.
The polishing pad 32 is provided on the rotary surface plate 31. The polishing pad 32 is provided on a contact surface with the polishing target surface S of the wafer W during the polishing processing.
The depositing table 50 includes a rotary surface plate 51 and the depositing pad 52.
The rotary surface plate 51 is rotatably provided. The rotary surface plate 51 is, for example, a table having a smaller diameter than that of the rotary surface plate 31 of the polishing table 30. The rotary surface plate 51 rotates, for example, in an orbital scheme. In other words, the rotary surface plate 51 moves in a smaller circle.
The depositing pad 52 is provided on the rotary surface plate 51. The depositing pad 52 is provided on a contact surface with the polishing target surface S of the wafer W during the deposition processing. Since the depositing pad 52 is provided, the slurry L can be prevented from flying off the depositing table 50. Accordingly, the slurry L can be more likely to be held on the depositing table 50.
The depositing pad 52 has a larger elastic modulus than the rotary surface plate 51. The depositing pad 52 preferably has a relatively large elastic modulus. Accordingly, the particles P are more likely to be fixed to stepped or concave portions of the polishing target surface S. The depositing pad 52 contains, for example, polyurethane.
The controller 90 receives the drive current detected by the drive current detector 211. The controller 90 controls the particle supplier 60 based on the drive current of the polishing head 21 during rotation. The drive current of the polishing head 21 potentially changes in accordance with the viscosity of the slurry L. Thus, the drive current of the polishing head 21 may be used to determine the viscosity of the slurry L. Accordingly, the viscosity of the slurry L can be adjusted to desired viscosity during the deposition processing.
The configuration of the polishing head 21 will be described below.
When the particles P are fixed onto the polishing target surface, the polishing head 21 spins and the depositing table 50 rotates, for example, in the orbital scheme.
During the deposition processing, the polishing head 21 pressurizes the wafer W toward the depositing table 50. The polishing head 21 pressurizes the wafer W toward the polishing table 30 during the polishing processing as well.
During swing of the swing arm 22, the polishing head 21 adsorbs the wafer W onto the back surface.
The depositing table 50 and its peripheral components will be described below.
The particle supplier 60 includes the dropper 61. The dropper 61 supplies the slurry L onto the depositing table 50 by dropping the slurry L from above the depositing table 50. The dropper 61 includes, for example, a nozzle or a pipe. The slurry L includes abrasive liquid containing particles at least. The abrasive liquid may include, for example, a solvent such as water in addition to the particles. The slurry L may additionally include at least one of water, warm water, or liquid chemical.
The dropper 61 includes a mixer 611. The mixer 611 mixes, for example, at least one of water, warm water, abrasive liquid, or liquid chemical (not illustrated).
The warm water has a higher temperature than the water. The temperature of the slurry L is adjusted by mixing the water and the warm water. It is possible to promote evaporation of the solvent (for example, water) in the slurry L by adjusting the temperature of the slurry L, thereby increasing the concentration of the particles P in the slurry L. As a result, the particles P are more likely to be fixed onto the polishing target surface S of the wafer W.
In the example illustrated in
Details of the slurry L will be described later with reference to
The gas supplier 70 supplies gas onto the depositing table 50. The supplier 70 includes, for example, a spray nozzle. The gas supplier 70 sprays, for example, clean dry air (CDA). The gas supplier 70 may supply inert gas such as N2. Since gas is supplied, evaporation of the solvent (for example, water) in the slurry L can be promoted and the concentration of the particles P in the slurry L can be increased. As a result, the particles P are more likely to be fixed onto the polishing target surface S of the wafer W.
The gas supplier 70 preferably supplies gas (hot air) having a temperature higher than room temperature. Accordingly, evaporation of the solvent (for example, water) in the slurry L can be further promoted and the concentration of the particles P in the slurry L can be further increased.
The particle supplier 60 includes, for example, a plurality of supply tubes 62. The supply tubes 62 penetrate through the rotary surface plate 51 (depositing table 50) and are opened at a contact surface of the depositing table 50, which contacts the polishing target surface S of the wafer W. The water, the warm water, the abrasive liquids A, B, and C, and the liquid chemical (not illustrated) are supplied onto the depositing table 50 through the supply tubes 62.
The particle supplier 60 may have a configuration in any one or both of the example illustrated in
The wafer W includes a semiconductor substrate 110, a wiring 120, and a film 130.
The semiconductor substrate 110 is, for example, a silicon substrate.
The wiring 120 is provided on the semiconductor substrate 110. The wiring 120 contains, for example, a conductive metal.
The film 130 is provided on the semiconductor substrate 110 and the wiring 120. The film 130 is, for example, an insulating film. The upper surface of the film 130 corresponds to the polishing target surface S of the wafer W and has a concave-convex shape in accordance with the pattern of the wiring 120.
In the example illustrated in
However, an aggregate Pa cannot enter a relatively small concave portion in some cases. In such a case, a void remains in the relatively small concave portion, and the concave portion cannot be protected during the polishing processing. In other words, the fixation state of the aggregate Pa (the particles P) to the polishing target surface S potentially changes depending on the flocculation state of the aggregate Pa.
Thus, at least one of a flocculant or a dispersant as liquid chemical is added to the slurry L. The flocculant flocculates the particles P. The dispersant disperses the particles P. Accordingly, the size of each aggregate Pa can be adjusted. As a result, the likelihood of fixation of the aggregate Pa (particles P) to a stepped portion or a concave portion can be adjusted in accordance with the surface state of the polishing target surface S. The flocculant contains, for example, a polymer. The dispersant contains, for example, a surfactant. Moreover, the particles P preferably have a plurality of particle diameters for the likelihood of fixation to a stepped portion or a concave portion.
The configuration of the slurry L in the embodiment may be determined in advance based on, for example, particle flocculation, the surface state of the polishing target surface S, and/or adhesion of the polishing target surface S and a formed aggregate.
The rotary surface plate 51 preferably contains a material having a relatively high thermal conductivity to adjust the temperature of the slurry L. The rotary surface plate 51 contains, for example, SiC.
The depositing table 50 further includes a table temperature control system 53, a metal plate 54, and a thermal insulator 55.
The table temperature control system 53 adjusts the temperature of the depositing table 50 (slurry L). The table temperature control system 53 is, for example, an infrared heater. The table temperature control system 53 is provided inside the depositing table 50. The table temperature control system 53 adjusts the temperature of the depositing table 50 to, for example, 25° C. to 80° C., more preferably, to 65° C. to 75° C. Temperature adjustment of the slurry L can be performed through temperature adjustment of the depositing table 50. Accordingly, evaporation of the solvent (for example, water) in the slurry L can be promoted and the concentration of the particles P in the slurry L can be increased. As a result, the particles P are more likely to be fixed onto the polishing target surface S of the wafer W.
The metal plate 54 is provided on a surface of the rotary surface plate 51, which faces the table temperature control system 53. The temperature of the depositing table 50 can be adjusted as the metal plate 54 absorbs infrared radiation radiated from the table temperature control system 53. The metal plate 54 contains, for example, Cu or Al.
The thermal insulator 55 is provided covering the supply tubes 62. The thermal insulator 55 and the supply tubes 62 have, for example, a double piping structure. The thermal insulator 55 is made of a heat insulation material.
The table temperature control system 53 includes a heater plate 531 and a heat generation body 532.
The heater plate 531 is a heater board. In the example illustrated in
The heat generation body 532 is electrically connected to two terminals T1 and T2. The heat generation body 532 is supplied with electric power from the two terminals T1 and T2 and generates heat. The heat generation body 532 is, for example, a Ni—Cr heat generation body.
The depositing pad 52 contains a filler 521 and a pore (void) 522.
The filler 521 has a relatively high thermal conductivity. Accordingly, the thermal conductivity of the depositing pad 52 is improved and the temperature of the slurry L can be more appropriately adjusted. The filler 521 contains, for example, Al2O3 or AlN. The material of the filler 521 is not limited to these materials.
A plurality of pores 522 are formed in the depositing pad 52. The shape of each pore 522 is, for example, substantially spherical.
A polishing method using the polishing apparatus 1 will be described below. The polishing method according to the embodiment includes the deposition processing and the polishing processing.
First, the table temperature control system 53 starts increasing the temperature of the depositing table 50, and the particle supplier 60 supplies the slurry L onto the depositing table 50 by continuous discharge. The particle supplier 60 can increase the temperature of the slurry L by supplying warm water.
Subsequently, the depositing table 50 rotates and the gas supplier 70 supplies CDA onto the depositing table 50. The particle supplier 60 switches continuous discharge to intermittent discharge and supplies the slurry L.
Subsequently, the particle supplier 60 stops supplying the slurry L and the depositing table 50 stops rotating.
Subsequently, the transfer device 20 conveys the wafer W onto the depositing table 50 and pressurizes the wafer W toward the depositing table 50. The depositing table 50 rotates. Accordingly, the deposition processing is performed.
Subsequently, the controller 90 causes the particle supplier 60 to supply the slurry L as necessary during the deposition processing. The gas supplier 70 supplies CDA to an outer peripheral part of the depositing table 50.
The controller 90 keeps receiving the drive current of the rotating polishing head 21 during the deposition processing. For example, the drive current potentially increases as the viscosity of the slurry L increases during the deposition processing. The controller 90 controls the particle supplier 60 based on change of the drive current of the rotating polishing head 21 during the deposition processing. More specifically, the controller 90 causes the particle supplier 60 to supply the slurry L when the drive current of the rotating polishing head 21 becomes equal to or larger than a first predetermined value during the deposition processing. Accordingly, the viscosity of the slurry L can be adjusted to desired viscosity during the deposition processing.
At end of the deposition processing, the particle supplier 60 and the gas supplier 70 stop supplying the slurry L and CDA and the depositing table 50 stops rotating.
Subsequently, the polishing head 21 adsorbs the wafer W and the transfer device 20 conveys the wafer W to the polishing table 30.
Subsequently, the pad conditioner 82 performs dressing of the depositing pad 52 as necessary.
Subsequently, the polishing table 30 polishes the polishing target surface S of the wafer W on which the particles P are fixed. In other words, the polishing processing is performed.
The above-described deposition processing and polishing processing are repeatedly performed. The timing of switching between the deposition processing and the polishing processing is set in advance, for example.
A semiconductor device manufacturing method using the polishing apparatus 1 will be described below.
First, the semiconductor substrate 110 on which the film 130 is formed is prepared as illustrated in the upper part of
As illustrated in the upper part of
Subsequently, the film 130 is polished as illustrated in the lower part of
As described above, according to the first embodiment, the particle supplier 60 supplies the slurry L containing the particles P onto the depositing table 50 so that the particles P are fixed onto at least part of the polishing target surface S contacting the depositing table 50. Accordingly, polishing can be performed flatter.
The polishing table 30 and the depositing table 50 are housed in the one chamber 10. The polishing table 30 and the depositing table 50 are disposed adjacent to each other. Accordingly, the particles P fixed on the polishing target surface S can be prevented from peeling off during conveyance of the wafer W from the depositing table 50 to the polishing table 30.
Rotation of the depositing table 50 is not limited to the orbital scheme but may be a rotary scheme.
The abrasive liquids A, B, and C having temperature increased to 40° C. approximately in advance may be supplied in place of supply of warm water.
No depositing pad 52 may be provided. In this case, the rotary surface plate 51 directly contacts the polishing target surface of the wafer W.
The controller 90 may control the particle supplier 60 based on change of drive current of the depositing table 50 instead of the drive current of the polishing head 21. In this case, the drive current detector 211 detects drive current flowing through a rotational drive mechanism of the depositing table 50.
No controller 90 may be provided. In this case, supply of the slurry L by the particle supplier 60 during the deposition processing is set in advance.
As illustrated in the lower part of
However, the deposition processing is performed in the first embodiment. Accordingly, the particles P are fixed to concave portions of the polishing target surface S of the wafer W and protect the concave portions during the polishing processing. As a result, polishing can be performed flatter irrespective of the pattern of the wiring 120 as illustrated in
In a case where the film 130 having large steps is flattened, low parts among the steps are polished as well, which potentially makes it difficult to flatten.
However, in the first embodiment, the particles P are fixed to stepped portions of the polishing target surface S and protect the stepped portions during the polishing processing. Accordingly, the polishing target surface S having large steps can be polished flatter.
The table temperature control system 53 further includes a circulation path 534. The circulation path 534 is provided inside the heater plate 531 so that circulating water passes through it. The circulating water is cooling water or warm water. The temperature of the depositing table 50 can be decreased by the cooling water. The temperature of the depositing table 50 can be increased by the warm water. Accordingly, the temperature of the depositing table 50 can be more appropriately adjusted.
In the example illustrated in
The configuration of the table temperature control system 53 may be changed as in the second embodiment. The polishing apparatus 1 according to the second embodiment can achieve the same effects as in the first embodiment.
The table temperature control system 53 is embedded in the rotary surface plate 51 as part of the rotary surface plate 51. The upper surface of the table temperature control system 53 is exposed at the upper surface of the rotary surface plate 51 (upper surface of the depositing table 50). In this case, the table temperature control system 53 rotates with the rotary surface plate 51. The supply tubes 62 and the thermal insulator 55 are provided through inside of the table temperature control system 53.
Since the table temperature control system 53 is exposed from the rotary surface plate 51 at the upper surface of the rotary surface plate 51, heat can be easily transferred to the wafer W and the slurry L. As a result, temperature adjustment can be more appropriately performed. Temperature adjustment can be further more appropriately performed in a case where the thermal conductivity of the material of the heater plate 531 is higher than the thermal conductivity of the material of the rotary surface plate 51. The material of the heater plate 531 is, for example, AlN. The thermal conductivity of AlN is, for example, 170 W/(m·° C.). The material of the rotary surface plate 51 is, for example, SiC. The thermal conductivity of SiC is, for example, 100 W/(m·° C.).
The table temperature control system 53 further includes a metal plate 533. The metal plate 533 is provided above the heat generation body 532. Moreover, the metal plate 533 is provided between the upper surface of the heater plate 531 and the heat generation body 532 inside the heater plate 531. Accordingly, heat generated at the heat generation body 532 can be easily transferred to the upper surface of the heater plate 531, in other words, the upper surface of the depositing table 50. The metal plate 533 contains, for example, Cu or Al.
The configuration of the depositing table 50 may be changed as in the third embodiment. The polishing apparatus 1 according to the third embodiment can achieve the same effects as in the first embodiment.
The configuration of the table temperature control system 53 may be changed as in the fourth embodiment. The polishing apparatus 1 according to the fourth embodiment can achieve the same effects as in the second and third embodiments.
A fifth embodiment is different from the first embodiment in that the drive current of the polishing head 21 is used to control the timing of switching between the deposition processing and the polishing processing.
The controller 90 controls the timing of switching between the deposition processing and the polishing processing based on change of the drive current of the rotating polishing head 21. The drive current of the polishing head 21 potentially changes in accordance with the situation of fixation of the particles P on the polishing target surface S of the wafer W. For example, the drive current potentially increases when the particles P are completely embedded in stepped or concave portions of the polishing target surface S during the deposition processing. However, the drive current potentially decreases when the particles P peel off the stepped or concave portions of the polishing target surface S during the polishing processing. Thus, the drive current of the polishing head 21 may be used to determine the timing of switching between the deposition processing and the polishing processing.
The controller 90 ends the deposition processing and conveys the wafer W from the depositing table 50 to the polishing table 30 when the drive current of the rotating polishing head 21 becomes equal to or larger than a second predetermined value during the deposition processing. In other words, the deposition processing ends when it is determined that the particles P are sufficiently fixed.
The controller 90 ends the polishing processing and conveys the wafer W from the polishing table 30 to the depositing table 50 when the drive current of the rotating polishing head 21 becomes equal to or smaller than a third predetermined value during the polishing processing. In other words, the polishing processing ends when it is determined that the fixed particles P peel off.
The controller 90 may control the timing of switching between the deposition processing and the polishing processing based on change of the drive current of each of the polishing table 30 and the depositing table 50 instead of the drive current of the polishing head 21. In this case, the drive current detector 211 detects the drive current flowing through the rotational drive mechanism of each of the polishing table 30 and the depositing table 50.
The drive current of the polishing head 21 may be used to control the timing of switching between the deposition processing and the polishing processing as in the fifth embodiment. The polishing apparatus 1 according to the fifth embodiment can achieve the same effects as in the first embodiment. Moreover, the polishing apparatus 1 according to the fifth embodiment may be combined with the second to fourth embodiments.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2023-039030 | Mar 2023 | JP | national |
