Patent Publication Number: US-11020839-B2

Title: Apparatus of supplying slurry for planarization process and chemical-mechanical-polishing system including the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority of U.S. Provisional Application No. 62/686,189 filed on Jun. 18, 2018, the disclosure of which is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present inventive concept relates to an apparatus of supplying slurry for a planarization process and a chemical-mechanical-polishing system including the same. 
     DISCUSSION OF RELATED ART 
     Integrated circuit chips are formed by multiple layers on a semiconductor substrate. In stacking the multiple layers, each layer may be planarized for its subsequent stacking of another layer using a planarization process such as a chemical-mechanical-polishing (CMP) process. 
     CMP processes may be performed in CMP stations using slurry delivered from a slurry supply unit. The slurry may contain an abrasive such as colloidal silicon dioxide or alumina, deionized water, and chemical solvents or oxidants such as hydrogen peroxide, potassium or ammonium hydroxide. When a delivery path of the slurry from the slurry supply unit to the CMP stations has deadlegs of a stagnant flow, the slurry may accumulate and/or solidify in the deadlegs. This agglomeration may make maintaining proper slurry concentrations and quality difficult to achieve. 
     SUMMARY 
     According to an exemplary embodiment of the present inventive concept, an apparatus of supplying slurry for a planarization process includes a housing having a first side and a second side and a plurality of channels extending through the housing from the first side to the second side along a first direction. The channels include a first channel connecting a first inlet on the first side and a first outlet on the second side, a second channel connecting a second outlet on the first side and a second inlet on the second side, a third channel connecting a third inlet on the first side and a third outlet on the second side, and a fourth channel connecting a fourth outlet on the first side and a fourth inlet on the second side. An intermediate portion of the second channel crisscrosses an intermediate portion of the third channel along a second direction crossing the first direction. 
     According to an exemplary embodiment of the present inventive concept, an apparatus of supplying slurry for a planarization process includes a housing having a first side and a second side, a first channel connecting a first inlet on the first side and a first outlet on the second side, a second channel connecting a second outlet on the first side and a second inlet on the second side, a third channel connecting a third inlet on the first side and a third outlet on the second side, a fourth channel connecting a fourth outlet on the first side and a fourth inlet on the second side, a first branch line selectively connecting the first channel and the third channel using a first valve, and a second branch line selectively connecting the second channel and the fourth channel using a second valve. The second channel and the third channel extend in a first direction, crossing each other at a first cross-point and crossing each other back via a second cross-point. The first branch line and the second branch line each extends in a second direction crossing the first direction. 
     According to an exemplary embodiment of the present inventive concept, a chemical-mechanical polishing (CMP) system includes a plurality of slurry supply units, a redundancy box, at least two loops and a plurality of CMP stations. The slurry supply units include a first slurry supply unit and a second slurry supply unit. The redundancy box receives slurry from at least one of the first slurry supply unit and the second slurry supply unit. The two loops include an inner loop and an outer loop, each loop includes a supply line supplying the slurry from the redundancy box and a return line returning the slurry to the redundancy box. The CMP tools each receives the slurry from the supply line and performing a planarization process on a wafer using the slurry. The redundancy box includes a first channel connecting selectively the first slurry supply unit to the supply line of the inner loop, a second channel connecting selectively the return line of the inner loop to the first slurry supply unit, a third channel connecting selectively the second slurry supply unit to the supply line of the outer loop, a fourth channel connecting selectively the return line of the outer loop to the second slurry supply unit, a first branch line connecting selectively the first channel to an intermediate portion of the third channel, and a second branch line connecting selectively an intermediate portion of the second channel to the fourth channel. The intermediate portion of the second channel crisscrosses the intermediate portion of the third channel. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       These and other features of the present inventive concept will become more apparent by describing in detail exemplary embodiments thereof with reference to the accompanying drawings of which: 
         FIG. 1  shows a chemical-mechanical-polishing (CMP) system performing a planarization process on a wafer according to an exemplary embodiment; and 
         FIG. 2  shows a block diagram of a redundancy box according to an exemplary embodiment. 
     
    
    
     It will be appreciated that for simplicity and clarity of illustration, elements illustrated in the drawings have not necessarily been drawn to scale unless described otherwise. For example, the dimensions of some of the elements are exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals have been repeated among the drawings to indicate corresponding or analogous elements. 
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Exemplary embodiments of the present inventive concept will be described below in detail with reference to the accompanying drawings. However, the inventive concept may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. 
       FIG. 1  shows a chemical-mechanical-polishing (CMP) system  100  performing a planarization process on a wafer using a slurry distribution system according to an exemplary embodiment. 
     The CMP system  100  includes a plurality of CMP stations  110  and a slurry distribution system including a plurality of valve manifold boxes  120 , a plurality of slurry supply units including a first slurry supply unit  130 A and a second slurry supply unit  130 B, a redundancy box  140 , and a pressure transmitter box  150 . The slurry distribution system of the CMP system  100  further includes at least two loops including an inner loop and an outer loop to supply slurry from the slurry supply units and return the slurry to the slurry supply units. 
     The CMP stations  110  each receives slurry from at least one of the inner loop and the outer loop through one of the valve manifold boxes  120  and performs a planarization process on a wafer using the slurry supplied through one of the valve manifold boxes  120 . 
     The inner loop includes an upper inner supply line UISL supplying slurry from the redundancy box  140  to the CMP stations  110  and an upper inner return line UIRL returning the slurry not consumed by the CMP stations  110  to the redundancy box  140 . The outer loop includes an upper outer supply line UOSL supplying slurry from the redundancy box  140  to the CMP stations  110  and an upper outer return line UORL returning the slurry not consumed by the CMP stations  110  to the redundancy box  140 . In an exemplary embodiment, the CMP stations  110  may receive slurry from at least one of the upper inner supply line UISL and the upper outer supply line UOSL according to the operation of the valve manifold boxes  120 . The valve manifold boxes  120  may circulate the slurry along the inner loop and the outer loop, supplying the slurry from either the inner loop or the outer loop to one of the CMP stations  110 . 
     The redundancy box  140  receives slurry from at least one of the first slurry supply unit  130 A and the second slurry supply unit  130 B. In an exemplary embodiment, the first slurry supply unit  130 A and the second slurry supply unit  130 B may have the same configuration. For example, each of the first slurry supply unit  130 A and the second slurry supply unit  130 B may include a slurry supply drum for slurry, a blender where the slurry is mixed and diluted with deionized water and a chemical(s) such as H 2 O 2  (hydrogen peroxide) and a pump. The pump may receive the mixed, diluted slurry and supply the slurry to the inner loop and the outer loop. The blender may receive slurry from the slurry supply drum. The blender may also receive the slurry that is not consumed in the CMP stations  110 . Unless defined otherwise, the mixed, diluted slurry may be referred to as slurry throughout the specification. 
     The first slurry supply unit  130 A may supply an outbound slurry to the redundancy box  140  through a first lower supply line FLSL and receive an inbound slurry from the redundancy box  140  through a first lower return line FLRL. The outbound slurry of the first slurry supply unit  130 A may circulate at least one of the inner loop and the outer loop in a clockwise direction, returning to the first slurry supply unit  130 A through the first lower return line FLRL. The second slurry supply unit  130 B may supply an outbound slurry to the redundancy box  140  through a second lower supply line SLSL and receive an inbound slurry from the redundancy box  140  through the second lower return line SLRL. The outbound slurry of the second slurry supply unit  130 B may circulate at least one of the inner loop and the outer loop in the clockwise direction, returning to the second slurry supply unit  130 B through the second lower return line SLRL. 
     For example, when the first slurry supply unit  130 A and the second slurry supply unit  130 B are working, the first slurry supply unit  130 A may supply an outbound slurry to the upper inner supply line UISL of the inner loop through the first lower supply line FLSL and the redundancy box  140 ; and the second slurry supply unit  130 B may supply an outbound slurry to the upper outer supply line UOSL of the outer loop through the second lower supply line SLSL and the redundancy box  140 . 
     The present inventive concept is not limited thereto. For example, the first slurry supply unit  130 A may supply slurry to the outer loop, and the second slurry supply unit  130 B may supply slurry to the inner loop. For the convenience of description, it is assumed that the first slurry supply unit  130 A supplies slurry to the inner loop, and the second slurry supply unit  130 B supplies slurry to the outer loop. 
     When one of the first slurry supply unit  130 A and the second slurry supply unit  130 B fails to provide slurry, the redundancy box  140  may supply an outbound slurry from a working slurry unit to both the inner loop and the outer loop. 
     For example, when the second slurry supply unit  130 B fails to provide slurry to the outer loop, the redundancy box  140  may enable the first slurry supply unit  130 A to supply an outbound slurry to both the inner loop and the outer loop. In this case, the outbound slurry from the first slurry supply unit  130 A may circulate both the inner loop and the outer loop in the clockwise direction using the redundancy box  140 . 
     As another example, when the first slurry supply unit  130 A fails to provide slurry to the inner loop, the redundancy box  140  may enable the second slurry supply unit  130 B to supply an outbound slurry to both the inner loop and the outer loop. In this case, the outbound slurry from the second slurry supply unit  130 B may circulate both the inner loop and the outer loop in the clockwise direction using the redundancy box  140 . 
     In an exemplary embodiment, the redundancy box  140  may have channels in a crisscross pattern to eliminate deadlegs in the channels so that an outbound slurry from at least one of the first slurry supply unit  130 A and the second slurry supply unit  130 B is supplied to both the inner loop and the outer loop without accumulation or solidification of slurry. 
     The configuration and operation of the redundancy box  140  will be described in detail with reference to  FIG. 2 . 
     The pressure transmitter box  150  may measure a point of use pressure of slurry flowing through the inner loop and the outer loop and feedback the measured pressure to the slurry supply units  130 A and  130 B so that a constant point of use pressure can be maintained. 
     The lines between the pressure transmitter box  150  and the redundancy box  140  may be referred to as an upper inner return line UIRL and an upper outer return line UORL. In this case, the inner loop further includes the upper inner return line UIRL, and the outer loop further includes the upper outer return line UORL. 
     In an exemplary embodiment, the CMP stations  110  may be located in a region A of a clean room while the redundancy box  140  and the first and second slurry supply units  130 A and  130 B may be located in a region B of a slurry room other than the clean room. 
       FIG. 2  shows a block diagram of a redundancy box  140  according to an exemplary embodiment. 
     The redundancy box  140  includes a housing  141  having a first side S 1  and a second side S 2 , and a plurality of channels extending through the housing from the first side S 1  to the second side S 2  along a first direction X. 
     The channels include a first channel  142 A connecting a first inlet I 1  on the first side S 1  and a first outlet O 1  on the second side S 2 , a second channel  142 B connecting a second outlet O 2  on the first side S 1  and a second inlet I 2  on the second side S 2 , a third channel  143 A connecting a third inlet I 3  on the first side S 1  and a third outlet O 3  on the second side S 2 , and a fourth channel  143 B connecting a fourth outlet O 4  on the first side S 1  and a fourth inlet I 4  on the second side S 2 . An intermediate portion of the second channel  142 B crisscrosses an intermediate portion of the third channel  143 A in a second direction Y crossing the first direction X. 
     In an exemplary embodiment, the first channel  142 A and the fourth channel  143 B extend in a straight line along the first direction X. The second channel  142 B and the third channel  143 A that cross each other in a crisscross pattern are disposed between the first channel  142 A and the fourth channel  143 B. 
     In an exemplary embodiment, the redundancy box  140  includes the first channel  142 A having a first system isolation valve SIV 1 , the second channel  142 B having a second system isolation valve SIV 2 , the third channel  143 A having a third system isolation valve SIV 3  and the fourth channel  143 B having a fourth system isolation valve SIV 4 . 
     The first channel  142 A may connect selectively the first slurry supply unit  130 A to the upper inner supply line UISL of the inner loop using the first system isolation valve SIV 1 . For example, to supply an outbound slurry from the first slurry supply unit  130 A to the upper inner supply line UISL, the first system isolation valve SIV 1  stays open so that slurry is allowed to pass from the first slurry supply unit  130 A to the upper inner supply line UISL; and to block the first slurry supply unit  130 A from supplying an outbound slurry to the upper inner supply line UISL for maintenance purpose, or when the first slurry supply unit  130 A fails, the first system isolation valve SIV 1  stays closed so that slurry cannot pass from the first slurry supply unit  130 A to the upper inner supply line UISL. 
     The second channel  142 B may connect selectively the upper inner return line UIRL of the inner loop to the first slurry supply unit  130 A using the second system isolation valve SIV 2 . For example, to supply an inbound slurry from the upper inner return line UIRL to the first slurry supply unit  130 A, the second system isolation valve SIV 2  stays open so that slurry is allowed to pass from the upper inner return line UIRL to the first slurry supply unit  130 A; and to block the first slurry supply unit  130 A from receiving an inbound slurry from the upper inner return line UIRL for maintenance purpose, or when the first slurry supply unit  130 A fails, the second system isolation valve SIV 2  stays closed so that slurry cannot pass from the upper inner return line UIRL to the first slurry supply unit  130 A. 
     The third channel  143 A may connect selectively the second slurry supply unit  130 B to the upper outer supply line UOSL of the outer loop using the third system isolation valve SIV 3 . For example, to supply an outbound slurry from the second slurry supply unit  130 B to the upper outer supply line UOSL, the third system isolation valve SIV 3  stays open so that slurry is allowed to pass from the second slurry supply unit  130 B to the upper outer supply line UOSL; and to block the second slurry supply unit  130 B from supplying an outbound slurry to the upper outer supply line UOSL for maintenance purpose, or when the second slurry supply unit  130 B fails, the third system isolation valve SIV 3  stays closed so that slurry cannot pass from the second slurry supply unit  130 B to the upper outer supply line UOSL. 
     The fourth channel  143 B may connect selectively the upper outer return line UORL of the outer loop to the second slurry supply unit  130 B using the fourth system isolation valve SIV 4 . For example, to supply an inbound slurry from the upper outer return line UORL to the second slurry supply unit  130 B, the fourth system isolation valve SIV 4  stays open so that slurry is allowed to pass from the upper outer return line UORL to the second slurry supply unit  130 B; and to block the second slurry supply unit  130 B from receiving an inbound slurry from the upper outer return line UORL for maintenance purpose, or when the second slurry supply unit  130 B fails, the fourth system isolation valve SIV 4  stays closed so that slurry cannot pass from the upper outer return line UORL to the second slurry supply unit  130 B. 
     The first lower supply line FLSL extends in the first direction X, connecting the first slurry supply unit  130 A to the first inlet I 1  of the redundancy box  140 . 
     The first lower return line FLRL extends in the first direction X, connecting the first slurry supply unit  130 A to the second outlet O 2  of the redundancy box  140 . 
     The second lower supply line SLSL extends in the first direction X, connecting the second slurry supply unit  130 B to the third inlet I 3  of the redundancy box  140 . 
     The second lower return line SLRL extends in the first direction X, connecting the second slurry supply unit  130 B to the fourth outlet O 4  of the redundancy box  140 . 
     The upper inner supply line UISL is connected to the first outlet O 1  of the redundancy box  140 ; the upper inner return line UIRL is connected to the second inlet I 2  of the redundancy box  140 ; the upper outer supply line UOSL is connected to the third outlet O 3  of the redundancy box  140 ; and the upper outer return line UORL is connected to the fourth inlet I 4  of the redundancy box  140 . 
     The first inlet I 1 , the second outlet O 2 , the third inlet I 3 , and the fourth outlet O 4  are arranged on the first side S 1  in that order along the second direction Y. The first outlet O 1 , the second inlet I 2 , the third outlet O 3 , and the fourth inlet I 4  are arranged on the second side S 2  in that order along the second direction Y. 
     The redundancy box  140  further includes a first branch line  144 A having a supply redundancy valve SRV and a second branch line  144 B having a return redundancy valve RRV. 
     The first branch line  144 A may connect selectively the first channel  142 A and an intermediate portion of the third channel  143 A to each other using the supply redundancy valve SRV. For example, when the first slurry supply unit  130 A and the second slurry supply unit  130 B are operating to supply slurry to the inner loop and the outer loop, respectively, the supply redundancy valve SRV stays closed, with the first system isolation valve SIV 1  and the second system isolation valve SIV 2  staying open; and when one of the first slurry supply unit  130 A and the second slurry supply unit  130 B fails and the other supplies slurry to the inner loop and the outer loop, the supply redundancy valve SRV stays open so that a working slurry supply unit supplies an outbound slurry to both the inner loop through the first channel  142 A and the outer loop through the third channel  143 A. In this case, the first channel  142 A and the third channel  143 A are connected to each other through the first branch line  144 A. When the working slurry supply unit is the first slurry supply unit  130 A and the second slurry supply unit  130 B is non-functional, the first slurry supply unit  130 A supplies the outbound slurry to both the inner loop and the outer loop, with the first system isolation valve SIV 1  staying open and the third system isolation valve SIV 3  staying closed. When the working slurry supply unit is the second slurry supply unit  130 B and the first slurry supply unit  130 A is non-functional, the second slurry supply unit  130 B supplies the outbound slurry to both the inner loop and the outer loop, with the first system isolation valve SIV 1  staying closed and the third system isolation valve SIV 3  staying open. 
     In an exemplary embodiment, the first branch line  144 A may include a plurality of branch lines and a plurality of supply redundancy valves. The supply redundancy valves may be controlled in the same manner. For example, the supply redundancy valves all may stay open or closed. For the convenience of description, the first branch line  144 A has two branch lines and two supply redundancy valves. 
     The first branch line  144 A may be extended in the second direction Y. 
     The second branch line  144 B may connect selectively the fourth channel  143 B and an intermediate portion of the second channel  142 B to each other using the return redundancy valve RRV. For example, when the first slurry supply unit  130 A and the second slurry supply unit  130 B are operating to receive slurry from the inner loop and the outer loop, respectively, the return redundancy valve RRV stays closed, with the third system isolation valve SIV 3  and the fourth system isolation valve SIV 4  staying open; and when one of the first slurry supply unit  130 A and the second slurry supply unit  130 B fails and the other supplies slurry, the return redundancy valve RRV stays open so that a working slurry supply unit receives an inbound slurry from both the inner loop through the second channel  142 B and the outer loop through the fourth channel  143 B. In this case, the second channel  142 B and the fourth channel  143 B are connected to each other through the second branch line  144 B. When the working slurry supply unit is the first slurry supply unit  130 A and the second slurry supply unit  130 B is non-functional, the first slurry supply unit  130 A receives the inbound slurry, with the second system isolation valve SIV 2  staying open and the fourth system isolation valve SIV 4  staying closed. When the working slurry supply unit is the second slurry supply unit  130 B and the first slurry supply unit  130 A is non-functional, the second slurry supply unit  130 B receives the inbound slurry, with the second system isolation valve SIV 2  staying closed and the fourth system isolation valve SIV 4  staying open. 
     In an exemplary embodiment, the second branch line  144 B may include a plurality of branch lines and a plurality of return redundancy valves. The return redundancy valves may be controlled in the same manner. For example, the return redundancy valves all may stay open or closed. For the convenience of description, the second branch line  144 B has two branch lines and two return redundancy valves. 
     The second branch line  144 B may be extended in the second direction Y. 
     In an exemplary embodiment, the second channel  142 B crisscrosses the third channel  143 A, with the second channel  142 B and the third channel  143 A each extending in the first direction X. For example, the second channel  142 B and the third channel  143 A cross each other at a first cross-point CP 1  and cross each other back via a second cross-point CP 2 . Note that the second channel  142 B and the third channel  143 A are not connected to each other at the cross-points CP 1  and CP 2 . For example, the second channel  142 B and the third channel  143 A may cross each other at the cross-points CP 1  and CP 2  by overlapping each other along a direction orthogonal to the XY plane. The intermediate portion of the third channel  143 A may include a portion of the third channel  143 A from the first cross-point CP 1  to the second cross-point CP 2 . The intermediate portion of the second channel  142 B may include a portion of the second channel  142 B from the first cross-point CP 1  to the second cross-point CP 2 . 
     The first branch line  144 A connects the intermediate portion of the third channel  143 A to the first channel  142 A, and the second branch line  144 B connects the intermediate portion of the second channel  142 B to the fourth channel  143 B. For example, the first branch line  144 A is disposed at a shortest distance between the first channel  142 A and the third channel  143 A, connecting the first channel  142 A to the intermediate portion of the third channel  143 A. For example, the second branch line  144 B is disposed at a shortest distance between the fourth channel  143 B and the second channel  142 B, connecting the fourth channel  143 B to the intermediate portion of the second channel  142 B. 
     In an exemplary embodiment, a shortest distance between the intermediate portion of the second channel  142 B and the fourth channel  143 B is less than a shortest distance between the intermediate portion of the third channel  143 A and the fourth channel  143 B. 
     In an exemplary embodiment, a shortest distance between the intermediate portion of the third channel  143 A and the first channel  142 A is less than a shortest distance between the intermediate portion of the second channel  142 B and the first channel  142 A. 
     The supply redundancy valve SRV may also be referred to as a first valve. The return redundancy valve RRV may also be referred to as a second valve. 
     The first internal recirculation valve IRV 1  may allow or block slurry flow between the first channel  142 A and the second channel  142 B. For example, if the first slurry supply unit  130 A is working, the first internal recirculation valve IRV 1  stays closed to block slurry flow between the first channel  142 A and the second channel  142 B. If the first slurry supply unit  130 A shuts down and the second slurry supply unit  130 B remains running, the second slurry supply unit  130 B may serve as a redundant system for providing slurry supply to the first channel  142 A and the second channel  142 B. In this case, the first internal recirculation valve IRV 1  stays open to allow slurry flow between the first channel  142 A and the second channel  142 B, while the system isolation valves SIV 1  and SIV 2  stay closed, thereby completing an internal recirculation of slurry flow between the supply pump of the first slurry supply unit  130 A, the first channel  142 A and the second channel  142 B. Furthermore, the internal recirculation mechanism prevents deadheading of the supply pump of the first slurry supply unit  130 A and stagnation of slurry within the piping of this unit, while maintaining supply pump speed to mitigate pressure fluctuation during redundancy removal (closure of the first internal recirculation valve IRV 1  and the reestablishment of the original slurry flow path by the first slurry supply unit  130 A via channels  142 A and  142 B once the system isolation valves SIV 1  and SIV 2  reopen, respectively). 
     The second internal recirculation valve IRV 2  may allow or block slurry flow between the third channel  143 A and the fourth channel  143 B. For example, if the second slurry supply unit  130 B is working, the second internal recirculation valve IRV 2  stays closed to block slurry flow between the third channel  143 A and the fourth channel  143 B. If the second slurry supply unit  130 B shuts down and the first slurry supply unit  130 A remains running, the first slurry supply unit  130 A may serve as a redundant system for providing slurry supply to the third channel  143 A and the fourth channel  143 B. In this case, the second internal recirculation valve IRV 2  stays open to allow slurry flow between the third channel  143 A and the fourth channel  143 B, while the system isolation valves SIV 3  and SIV 4  stay closed, thereby completing an internal recirculation of slurry flow between the supply pump of the second slurry supply unit  130 B, the third channel  143 A and the fourth channel  143 B. Furthermore, the internal recirculation mechanism prevents deadheading of the supply pump of the second slurry supply unit  130 B and stagnation of slurry within the piping of this unit, while maintaining supply pump speed to mitigate pressure fluctuation during redundancy removal (closure of the second internal recirculation valve IRV 2  and the reestablishment of the original slurry flow path by the second slurry supply unit  130 B via channels  143 A and  143 B once the system isolation valves SIV 3  and SIV 4  reopen, respectively). 
     The first internal recirculation valve IRV 1  may also be referred to as a third valve, and the second internal recirculation valve IRV 2  may also be referred to as a fourth valve. 
     While the present inventive concept has been shown and described with reference to exemplary embodiments thereof, it will be apparent to those of ordinary skill in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the inventive concept as defined by the following claims.