Mater. Res. Soc. Symp. Proc. Vol. 1249 © 2010 Materials Research Society
`
`1249-E02-04
`
`Design, Characteristics and Performance of Diamond Pad Conditioners
`
`Doug Pysher, Brian Goers, John Zabasajja
`3M Electronics Markets Materials Division, St. Paul, MN 55144
`
`ABSTRACT
`
`A wide range of diamond pad conditioner (disk) designs have been characterized and key
`performance metrics have been collected. Relationships between design characteristics
`including diamond size and shape, spatial density, and tip height distribution and polishing pad
`wear rates and pad surface textures have been established for a variety of pads.
`Estimation of the depth-of-penetration of working diamonds, from used disk analyses,
`allows meaningful topographic assessments of alternative conditioner designs and predictions of
`relative performance. An example of an improved conditioner that illustrates this design
`methodology is given.
`Conditioner aggressiveness and its decay in various slurries have been measured to assess
`disk lifetime in Chemical Mechanical Planarization (CMP) processes environments. Key factors
`affecting disk lifetime are discussed and an improved-lifetime conditioner for use in aggressive
`slurries will be reviewed.
`
`INTRODUCTION
`
`Diamond pad conditioners are used to prepare and maintain the surface of polishing pads
`used in CMP processes. The process advantages provided by proper pad conditioning have been
`reviewed elsewhere and include improvements in polishing rate and stability, planarization, and
`defectivity. [1]
`Key performance attributes of diamond pad conditioners are cut and finish, similar to
`many other abrasive products. What is rather unique, compared to other abrasive processes, is
`that the workpiece (the CMP pad) is used in a subsequent (or concurrent) polishing process, and
`needs to possess very specific attributes for optimal performance.
`CMP pad choices have evolved beyond the basic hard porous pad to include those
`developed for more specialized applications. Formulations are now available that include softer
`pads and finer pore structures for improved defectivity with copper and advanced low-k
`dielectric materials, more-durable pads for improved life, and solid pads. Conditioning
`requirements for these new classes of CMP pads have driven the evolution of new pad
`conditioner designs. Slurry choices have also evolved and influence conditioner selection for a
`particular application.
`
`DISCUSSION
`
`Pad Conditioner Design Space
`
`A useful concept to understand different classifications of pad conditioners is Design
`Space, which conveys the location of a particular disk design in terms of its two key performance
`attributes; finish and aggressiveness. These attributes describe the surface finish and also the
`aggressiveness or cutting ability that the conditioner imparts on a reference pad material. Both
`
`1
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`IPR2024-00534
`Samsung Electronics Co. Ltd. et al v. Chien-Min Sung
`Samsung's Exhibit 1015
`Ex. 1015, Page 1
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`

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`are measured using standardized test conditions and correlate well with analogous measurements
`on various CMP pads. Surface finish and aggressiveness of several conditioner types are shown
`in Figure 1.
`
`A
`250 μm
`semi-sharp
`
`180 μm
`semi-sharp
`
`B
`
`180 μm
`sharp
`
`125 μm
`sharp
`
`90 μm
`
`150 μm
`leveled
`
`45 μm
`
`53 μm
`
`C
`
`7.0
`
`6.0
`
`5.0
`
`4.0
`
`3.0
`
`2.0
`
`1.0
`
`Surface Finish (μm)
`
`0.0
`
`0
`
`10
`15
`20
`25
`30
`Aggressiveness Number
`Figure 1. Surface finish and aggressiveness map for a variety of pad conditioner designs
`
`5
`
`35
`
`40
`
`First-generation disks were made using 250 μm semi-sharp diamonds. Their finish and
`aggressiveness tended to fall in the center of the map (region A). These designs work well in
`200 mm processes that use industry-standard hard, porous CMP pads. Second-generation pad
`conditioner designs incorporated improvements in flatness and also utilized smaller-sized
`diamonds, which shifted both finish and aggressiveness to lower values.
`With the introduction of 300 mm processes, conditioning requirements became more
`demanding, primarily due to the larger pads used. In this case, first-generation conditioners may
`not provide adequate lifetime to provide for multiple pad changes. This situation is even more-
`challenging if an aggressive slurry is used. By this, we mean a slurry that wears the diamonds on
`the conditioner at a relatively rapid rate. In order to improve conditioner lifetime, designs are
`needed in which the disk aggressiveness degrades at a slower rate. As seen in region B of Figure
`1, these disks have increased aggressiveness over the first generation disks.[2]
`New conditioner designs that utilize smaller sharp diamonds (region A, 125 μm sharp)
`show improved removal rates in tungsten polishing applications. Besides their use in aggressive
`
`2
`
`Ex. 1015, Page 2
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`

`

`slurries, these designs are also finding application on CMP pads that have more demanding
`conditioning requirements.
`Fine-finish pad conditioner designs tend to be in the lower left region of the map, as seen
`in region C of Figure 1. The need for this class of conditioners is driven primarily by new CMP
`pad formulations, as described below. In general, a finer pad finish can be obtained by using a
`conditioner with smaller diamond sizes. However, there are practical limits to reducing diamond
`size in pad conditioners. We have also developed fine-finish conditioners by improving the
`diamond tip height distribution. Such an example is illustrated by the 150 μm leveled design in
`region C of Figure 1.
`The design space concept has proven very useful. Plotting the attributes of a particular
`disk in this way allows one to select a new design for a particular application based on its desired
`performance attributes or its location relative to an existing design.
`
`Improvements in Fine-Finish Disk Design
`
`Advanced-node (90 nm and less) CMP processes have driven improved pad designs. An
`important aspect of these improved pads is the ability to design the pad properties to fit specific
`CMP needs [3]. Compared to first-generation pads, newer generation pads may contain smaller
`and lower volume of pores. In order to preserve the native porosity distribution, these pads
`require a conditioner that imparts a finer surface texture [4]. Other pad designs can reduce
`scratch counts when low cutting rates are employed which generate less pad debris [5]. Some of
`these advanced pads require conditioners which are in the “fine-finish” region of the design
`space (region C of Figure 1).
`One of our fine-finish disk designs, which utilizes small-sized diamonds, has been used
`successfully in a high-volume production environment. However, occasional wafer defect issues
`have been reported with this design in state-of-the-art copper polishing nodes. Post-use
`examination of suspect conditioners has provided valuable information regarding potential root
`causes of the defects and allowed for the development of an improved design which addresses
`these issues. Post-use examination of conditioners also provided information regarding the
`depth-of-penetration (DOP) of the working diamonds into the CMP pad. By locating and
`measuring the absolute elevations of worn diamonds, it was determined that the estimated DOP
`during use was approximately 15 μm. This information provides a meaningful scale in which to
`evaluate the current and improved disk designs.
`Investigation of the surface topography of the current disk design revealed a bumpy
`texture in the final sintered product, as shown in the 1 cm² area topography scan in Figure 2a.
`The topography irregularities may contribute to defects during the CMP process.
`A new design significantly improved the disk topography. A slightly-larger diamond size
`provided for improved diamond protrusion. A slightly-blockier diamond grade minimized the
`increase in pad wear rate (PWR) that was expected to accompany the increase in diamond size.
`PWR and surface finish of the disk were further optimized by improving the diamond tip height
`distribution. The surface topography and estimated contact area of the new design is shown in
`Figures 2b and 3b, respectively. With the new design, a significant increase in the number of
`working diamonds is observed at a 15 μm elevation, Figure 3b. Figure 4 compares two-
`dimensional surface profiles of the current and new fine-finish conditioners and illustrates the
`improvements in flatness and diamond height distribution.
`
`3
`
`Ex. 1015, Page 3
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`

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`The fine-finish disk design improvements were validated by polishing experiments. The
`current and improved design conditioners were compared by polishing blanket 200 mm copper
`wafers on an AMAT Mirra Mesa platform. The improved conditioner design provided similar
`removal rates and improved defect performance over the current design. Copper blanket wafer
`defect results are summarized in Table I.
`
` Table I. Defect results from blanket copper wafer polishing.
`SP1 micro-defect
`SP1 macro-defect
`count
`count
`88
`54
`129
`57
`75
`3
`67
`3
`9
`0
`0
`0
`
`no conditioning
`no conditioning
`current design
`current design
`improved design
`improved design
`
`μm
`
`0 2 4 6 8 1
`
`0
`
`12
`
`14
`
`16
`
`18
`
`20
`
`22
`
`24
`
`26
`
`28
`
`30
`
`32
`
`34
`
`36
`
`38
`
`μm
`
`0 2 4 6 8 1
`
`0
`
`12
`
`14
`
`16
`
`18
`
`20
`
`22
`
`24
`
`26
`
`28
`
`30
`
`32
`
`34
`
`36
`
`38
`
`40
`
`(a)
`(b)
`Figure 2. 1 cm² area scans comparing disk topography of a) current and b) improved fine-finish
`disk designs.
`
`4
`
`Ex. 1015, Page 4
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`

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`-15μm
`
`-15μm
`
`Area (%)
`
`90.2
`
`9.76
`
`Area (%)
`
`95.5
`
`4.46
`
`(a)
`(b)
`Figure 3. Surface topography slice at 15 μm elevation showing estimated contact area of the a)
`current and b) improved fine-finish disk designs.
`
`Length = 10 mm Pt = 39 μm Scale = 200 μm
`
`0
`
`0.5
`
`1
`
`1.5
`
`2
`
`2.5
`
`3
`
`3.5
`
`4
`
`4.5
`
`5
`
`5.5
`
`6
`
`6.5
`
`7
`
`7.5
`
`8
`
`8.5
`
`9
`
`9.5 mm
`
`(a)
`
`Length = 10 mm Pt = 37 μm Scale = 200 μm
`
`μm
`
`200
`
`150
`
`100
`
`50
`
`0
`
`μm
`
`200
`
`150
`
`100
`
`50
`
`0
`
`0
`
`0.5
`
`1
`
`1.5
`
`2
`
`2.5
`
`3
`
`3.5
`
`4
`
`4.5
`
`5
`
`5.5
`
`6
`
`6.5
`
`7
`
`7.5
`
`8
`
`8.5
`
`9
`
`9.5 mm
`
`(b)
`Figure 4. Surface profiles showing flatness of a) current and b) improved fine-finish disk
`designs.
`
`5
`
`Ex. 1015, Page 5
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`

`

`Effects of Slurry on Conditioner Lifetime and Performance
`
`Pad conditioning is just one of the dozens of process variables that affect CMP
`performance [6]. Control and stability of the conditioning process depends not only on the initial
`performance of the diamond pad conditioner, but how that performance changes over time. This
`change is primarily due to wear of the diamonds.
`In the context of conditioner life, it is important to understand how slurry affects diamond
`disk performance. There are additional variables in a given CMP process that affect conditioner
`life, such as platform (200 versus 300 mm), conditioning type (in-situ versus ex-situ) and cycle
`(100% versus 50%), platen and conditioner rotational speeds, CMP pad type, etc. In this paper,
`we will focus on the effect that slurry has on conditioner life.
`We evaluate conditioner lifetime with an accelerated life test, which utilizes in-situ
`conditioning on a Strasbaugh polisher to subject the diamonds on the conditioner to the same
`physical and chemical environment they encounter on wafer CMP tools. At the beginning of the
`test and at selected intervals during the test, the conditioner is removed and its aggressiveness is
`measured using a 3M standardized aggressiveness test. At the same time intervals, the CMP pad
`thickness is measured on the polisher. In this way, both the pad cut rate and the conditioner
`aggressiveness are monitored as a function of conditioning time.
`This accelerated life test was used to evaluate several different slurries on a baseline
`conditioner design (3M A160 Diamond Pad Conditioner). Figure 5 shows the total pad wear of
`an IC1000 pad after 3 hours of testing. The data are grouped into slurry families (W, Cu, Oxide)
`and sorted from highest to lowest within a family. A pad wear test of the same conditioner
`design using only DI water gives a total cut of about 4.2 mils in 3 hours under the same test
`conditions. Within a slurry family, a range in pad wear of about 2x can be observed. In general,
`pad wear is lowest in tungsten slurries. As a family, tungsten slurries tend to cause the most-
`severe diamond wear on the conditioner. With both copper and oxide slurries, pad wear can be
`either higher or lower than is observed when conditioning in DI water. The resulting pad wear
`depends on the balance between how aggressive the slurry is at wearing the diamonds and how
`effective the slurry is at wearing the pad.
`Pad conditioner design can be modified to counteract this aggressive wear and extend the
`disk lifetime. Figure 6 shows pad cut rates during an accelerated life test for various-sized sharp
`diamond conditioners that were tested in tungsten slurry that tends to aggressively wear
`diamonds. As seen in Figure 6, all three of the sharp-diamond conditioners had cut rates that
`were higher and decayed at a slower rate than that of a competitive disk. After 6 hours of
`testing, the competitive disk retained only about 15% of its initial cut rate whereas our sharp-
`diamond disks retained between 55 and 65% of their initial cut rates. These sharp-diamond
`conditioners provide about twice the lifetime as the competitive disk, determined by when the
`pad cut rate drops below a minimum value (shown by the horizontal dashed line in Figure 6).
`
`6
`
`Ex. 1015, Page 6
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`

`

`W
`Slurries
`
`Cu
`Slurries
`
`Oxide
`Slurries
`
`9
`
`8
`
`7
`
`6
`
`5
`
`4
`
`3
`
`2
`
`1
`
`0
`
`Pad wear at 3 hours (mils)
`
`Figure 5. Total pad wear after 3 hours of accelerated life testing in various CMP slurries.
`
`Although pad cut rate (and its decay with time) is a key property to consider when
`selecting a conditioner for use in aggressive slurries, other factors may influence the selection.
`Some CMP pads may benefit from more aggressive conditioning, regardless of the slurry. [7].
`Recently, we have observed improved tungsten removal rates when smaller-sized sharp diamond
`conditioners are utilized. This is consistent with published results that show a correlation
`between tungsten removal rates and pad texture (finer texture giving higher rates) [8].
`
`CONCLUSIONS
`
`The concept of a Pad Conditioner Design Space is useful to understand different
`classifications of diamond pad conditioners. It conveys the location of a particular disk design in
`terms of its two key performance attributes, finish and aggressiveness, and facilitates the
`selection a disk design for a particular CMP application.
`Post-use examination of conditioners provides information regarding the depth-of-
`penetration (DOP) of the working diamonds into the CMP pad. A new design with improved
`surface topography characteristics was developed which exhibits improved polishing
`performance.
`Conditioner aggressiveness and its decay in various slurries have been measured. Disks
`have been developed that exhibit improved lifetimes in aggressive slurries.
`
`7
`
`Ex. 1015, Page 7
`
`

`

` Accelerated Wear Test Pad Cut Rate vs. Conditioning Time
`IC1000 Peforated/Suba IV, W2000 (1:1), 3% H2O2, 6.5 lbs
`
`Competitor
`
`End of Life
`
`125 μm
`Type 9
`
`150 μm
`Type 9
`
`180 μm
`Type 9
`
`280
`
`260
`
`240
`
`220
`
`200
`
`180
`
`160
`
`140
`
`120
`
`100
`
`80
`
`60
`
`40
`
`20
`
`0
`
`Pad Cut Rate (μm/h)
`
`0
`
`1
`
`2
`
`3
`
`4
`
`5
`
`6
`
`7
`
`Conditioning Time (h)
`
`Figure 6. Pad cut rate decay curves during accelerated life testing in tungsten slurry of sharp
`diamond disks of varying diamond size (125, 150 and 180μm).
`
`ACKNOWLEDGEMENTS
`
`The authors would like to thank the CMP pad vendors for their cooperation and support
`in providing pads for conditioning evaluations. Thanks also to Tammy Engfer for providing
`tungsten polishing results.
`
`REFERENCES
`
`1. A.S. Lawing, CMP-MIC 33-42 (2005).
`2. T. Engfer, B. Goers, A. Zagrebelny, L. Zazzera, 12th International Symposium on CMP
`(CAMP) (2007).
`3. T. Kasai, C.W. Nam, S. Li, J. Kasthurirangan, W. Fortino, Y. Homma, S. Tanaka, A. Prasad,
`G. Gaudet, F. Sun, A. Naman, ICPT, 91-96 (2009)
`4. A. S. Lawing and C. Juras, ICPT, 25-30 (2007)
`5. S. Kamo, H. Miyauchi, H. Shida, ICPT, 279-284 (2009).
`6. G. Banerjee and R. Rhoades, ECS Trans., 13 [4] 1-19 (2008).
`7. F. Sun, J. Hawkins, J. Tsai, G. Chiu, A. Naman, ECS Trans., 18 [1] 517-522 (2009).
`8. M. Akaji, S. Haba, K. Yoshida, A. Isobe, M. Kinoshita, ICPT, 97-102 (2009).
`
`8
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`Ex. 1015, Page 8
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`