EP0004033A1 - Procédé pour égaliser l'enlèvement de matière au cours du polissage de plaquettes - Google Patents

Procédé pour égaliser l'enlèvement de matière au cours du polissage de plaquettes Download PDF

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Publication number
EP0004033A1
EP0004033A1 EP79100602A EP79100602A EP0004033A1 EP 0004033 A1 EP0004033 A1 EP 0004033A1 EP 79100602 A EP79100602 A EP 79100602A EP 79100602 A EP79100602 A EP 79100602A EP 0004033 A1 EP0004033 A1 EP 0004033A1
Authority
EP
European Patent Office
Prior art keywords
polishing
plate
pressure
disks
ring
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP79100602A
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German (de)
English (en)
Other versions
EP0004033B1 (fr
Inventor
Hans Chem.-Ing.grad. Krämer
Helmuth Chem.-Ing.Grad Kirschner
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Siltronic AG
Original Assignee
Wacker Siltronic AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Wacker Siltronic AG filed Critical Wacker Siltronic AG
Publication of EP0004033A1 publication Critical patent/EP0004033A1/fr
Application granted granted Critical
Publication of EP0004033B1 publication Critical patent/EP0004033B1/fr
Expired legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B37/00—Lapping machines or devices; Accessories
    • B24B37/04—Lapping machines or devices; Accessories designed for working plane surfaces
    • B24B37/042—Lapping machines or devices; Accessories designed for working plane surfaces operating processes therefor

Definitions

  • the invention relates to a method for equalizing the polishing removal of disks when polishing with polishing machines, which have a polishing plate covered with a polishing cloth, one or more polishing support plates, on the side facing the polishing plate, the polishing plate. Disks are cemented on, as well as pressure stamps that press the polishing carrier plates against the polishing plate covered with a polishing cloth.
  • the layer sequences of different conductivity types required for the function of the individual components are produced by successive individual processes, starting from the flat surfaces of the single-crystal semiconductor wafers.
  • Wavy, curved or wedge-shaped semiconductor wafers lead to blurring when exposing the photoresist applied to the wafer surface, in particular when using photolithographic methods. Components with a high circuit packing density can therefore no longer be produced from such panes.
  • the tolerances with regard to the thickness, the wedge shape or the flatness of the semiconductor wafers used in the processes, which are still accepted by the component manufacturers, are shifting to ever smaller values.
  • the slices with their flat - including a marking on the circumference of the slices to identify the crystallographic orientation of the respective slices materials is understood - cemented in the direction of the center of the carrier plate, this results in a wedge-shape perpendicular to the flat, with the flat coming to lie at the tip end of the wedge during the initial polishing runs up to about the tenth polishing run, while after about the thirtieth polishing run the flat is at thick end of the wedge lies. Due to this drive-dependent difference in thickness between the outer ring and the center ring, the roughly ten first polishing runs and the last polishing runs exceeding the number of thirty result in a relatively poor thickness tolerance of the polished discs.
  • the measured wedge is generally greater, the greater the difference between the average thickness value in the outer ring and the average thickness value in the middle ring. The thickness value is determined in the center of each slice.
  • the invention was therefore based on the object in the polishing process by means of suitable measures, an even pressure distribution and thus to all.
  • Set discs with equivalent removal forces in order to be able to guarantee semiconductor wafers with small tolerances with regard to their thickness, taper and ripple.
  • This object is achieved in that intermediate layers of soft, elastic bodies are inserted between the pressure stamp and the back of the carrier plate.
  • Elastic bodies are generally understood to mean elastic materials which can be compressed and compressed, and which have the tendency to reverse the deformations which occur under the action of deforming forces.
  • Particularly suitable are particularly soft, elastic bodies with pressure compensation chambers, for example graphite or silicone foams, plastic foams, such as polyethylene foams, where the pressure compensation chambers can be filled with either gas or liquid.
  • Air cushion foils such as in particular polyethylene foils of different thicknesses with air knobs of different diameters, are preferably used.
  • Figure 1 shows schematically the part of a conventional polishing machine that is relevant to the invention.
  • Figure 2 shows the front of a carrier plate with cemented discs to be polished.
  • Figures 3a to 3d show 4 differently shaped elastic intermediate layers.
  • polishing semiconductor wafers 1 When polishing semiconductor wafers 1, for example, they are usually cemented in concentric rings onto a flat front side of a carrier plate 2, which is usually made of V2A steel or aluminum. Before the pressure stamp 3 is placed on the back of the carrier plate, a soft, elastic intermediate layer 4 is inserted.
  • the pressure stamp 3 of conventional polishing machines is provided with a cooling system which dissipates the frictional heat that occurs during polishing.
  • this cooling system consists of a cavity 5, through which a coolant, in the simplest case of water, flows through the feed pipes 6 and 7.
  • the pressure with which the disks 1 to be polished are pressed against the polishing cloth 9 clamped on the polishing plate 8 is generated by the pressure cylinder 11 attached to the cylinder rod 10.
  • the polishing plate 8 is set in rotation by means of a suitable drive.
  • the system of the carrier plate 2 and the plunger 3 with the cooling system 5 (cooling pot), which is connected to the rigid pressure cylinder 11 by means of the sliding bearing 12, is rotated in the same direction.
  • a carrier plate 2 is shown, on which silicon disks are cemented in three kit rings, the outer kit ring 13, the middle kit ring 14 and the inner kit ring 15.
  • the number of kit rings generally depends on the size of the carrier plates used and the diameter of the discs to be polished.
  • a support plate 2 is for example shown, are cemented in which semiconductor wafers in an outer cement ring 13, in a middle cement ring 14 and in an inner cement ring 1. 5
  • the average thickness value in the outer kit ring 13 is, however, smaller than the average thickness value of the middle kit ring 14
  • circular inserts with a diameter substantially smaller than the carrier plate diameter for example inserts as shown in Figure 3d, must be inserted .
  • These deposits transfer the polishing pressure in the plate center. This results in an increase in the polishing removal in the inner plate area.
  • there are smaller differences in the thickness values in the outer and middle kit ring and thus lead to an improvement in the thickness spread and in particular the wedge shape perpendicular to the flat.
  • the removal in the inner plate area is increased, the smaller the diameter of these center inserts.
  • the influences of the back of the carrier plate and the pressure stamp or the underside of the cooling pot can be largely eliminated.
  • the influence of the polishing cloth can also be reduced by the choice of inexpensive insert forms, whereby a considerable improvement with regard to the scatter of thickness and the wedge shape of polished discs of a polishing carrier plate is achieved.
  • each slice was measured in 5 points, namely in the middle and in four points, each separated by 90 ° on the circumference of the slice, starting in the middle of the flat.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)
  • Grinding Of Cylindrical And Plane Surfaces (AREA)
EP79100602A 1978-03-03 1979-03-01 Procédé pour égaliser l'enlèvement de matière au cours du polissage de plaquettes Expired EP0004033B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE2809274 1978-03-03
DE19782809274 DE2809274A1 (de) 1978-03-03 1978-03-03 Verfahren zur vergleichmaessigung des polierabtrages von scheiben beim polieren

Publications (2)

Publication Number Publication Date
EP0004033A1 true EP0004033A1 (fr) 1979-09-19
EP0004033B1 EP0004033B1 (fr) 1981-01-07

Family

ID=6033513

Family Applications (1)

Application Number Title Priority Date Filing Date
EP79100602A Expired EP0004033B1 (fr) 1978-03-03 1979-03-01 Procédé pour égaliser l'enlèvement de matière au cours du polissage de plaquettes

Country Status (4)

Country Link
US (1) US4270316A (fr)
EP (1) EP0004033B1 (fr)
JP (1) JPS54120490A (fr)
DE (2) DE2809274A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5980361A (en) * 1996-12-12 1999-11-09 Wacker Siltronic Gesellschaft Fur Halbleitermaterialien Ag Method and device for polishing semiconductor wafers
US6095898A (en) * 1997-10-30 2000-08-01 Wacker Siltronic Gesellschaft Fur Halbleitermaterialien Ag Process and device for polishing semiconductor wafers
US6404557B2 (en) * 1999-09-10 2002-06-11 Inviso, Inc. Display illumination system

Families Citing this family (48)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5789551A (en) * 1980-11-17 1982-06-03 Toshiba Corp Grinding process for sapphire wafer
US5040336A (en) * 1986-01-15 1991-08-20 The United States Of America As Represented By The Secretary Of The Air Force Non-contact polishing
US4850157A (en) * 1987-11-23 1989-07-25 Magnetic Peripherals Inc. Apparatus for guiding the flow of abrasive slurry over a lapping surface
US4930259A (en) * 1988-02-19 1990-06-05 Magnetic Perpherals Inc. Magnetic disk substrate polishing assembly
US5193316A (en) * 1991-10-29 1993-03-16 Texas Instruments Incorporated Semiconductor wafer polishing using a hydrostatic medium
DE4139205A1 (de) * 1991-11-28 1993-06-03 Wacker Chemitronic Verfahren zur herstellung lagerstabiler oberflaechen von siliciumscheiben mit vorteilhaften oxidationseigenschaften
US5205082A (en) * 1991-12-20 1993-04-27 Cybeq Systems, Inc. Wafer polisher head having floating retainer ring
US5472374A (en) * 1992-08-10 1995-12-05 Sumitomo Metal Mining Co., Ltd. Polishing method and polishing device using the same
MY114512A (en) 1992-08-19 2002-11-30 Rodel Inc Polymeric substrate with polymeric microelements
US5562529A (en) * 1992-10-08 1996-10-08 Fujitsu Limited Apparatus and method for uniformly polishing a wafer
US5377451A (en) * 1993-02-23 1995-01-03 Memc Electronic Materials, Inc. Wafer polishing apparatus and method
US5443416A (en) * 1993-09-09 1995-08-22 Cybeq Systems Incorporated Rotary union for coupling fluids in a wafer polishing apparatus
JP3311116B2 (ja) * 1993-10-28 2002-08-05 株式会社東芝 半導体製造装置
US5643053A (en) 1993-12-27 1997-07-01 Applied Materials, Inc. Chemical mechanical polishing apparatus with improved polishing control
JP3042293B2 (ja) * 1994-02-18 2000-05-15 信越半導体株式会社 ウエーハのポリッシング装置
JPH07241764A (ja) * 1994-03-04 1995-09-19 Fujitsu Ltd 研磨装置と研磨方法
US6024630A (en) 1995-06-09 2000-02-15 Applied Materials, Inc. Fluid-pressure regulated wafer polishing head
US5681215A (en) * 1995-10-27 1997-10-28 Applied Materials, Inc. Carrier head design for a chemical mechanical polishing apparatus
US6746565B1 (en) * 1995-08-17 2004-06-08 Semitool, Inc. Semiconductor processor with wafer face protection
US5762544A (en) * 1995-10-27 1998-06-09 Applied Materials, Inc. Carrier head design for a chemical mechanical polishing apparatus
USRE38854E1 (en) * 1996-02-27 2005-10-25 Ebara Corporation Apparatus for and method for polishing workpiece
US5738568A (en) * 1996-10-04 1998-04-14 International Business Machines Corporation Flexible tilted wafer carrier
US6036587A (en) * 1996-10-10 2000-03-14 Applied Materials, Inc. Carrier head with layer of conformable material for a chemical mechanical polishing system
US5716258A (en) * 1996-11-26 1998-02-10 Metcalf; Robert L. Semiconductor wafer polishing machine and method
US6442975B1 (en) 1996-12-26 2002-09-03 Hoya Corporation Method of manufacturing thin-plate glass article, method of manufacturing glass substrate for information recording medium, and method of manufacturing magnetic recording medium
US5851140A (en) * 1997-02-13 1998-12-22 Integrated Process Equipment Corp. Semiconductor wafer polishing apparatus with a flexible carrier plate
US6056632A (en) * 1997-02-13 2000-05-02 Speedfam-Ipec Corp. Semiconductor wafer polishing apparatus with a variable polishing force wafer carrier head
US6425812B1 (en) 1997-04-08 2002-07-30 Lam Research Corporation Polishing head for chemical mechanical polishing using linear planarization technology
US6244946B1 (en) 1997-04-08 2001-06-12 Lam Research Corporation Polishing head with removable subcarrier
US5885135A (en) * 1997-04-23 1999-03-23 International Business Machines Corporation CMP wafer carrier for preferential polishing of a wafer
TW375550B (en) * 1997-06-19 1999-12-01 Komatsu Denshi Kinzoku Kk Polishing apparatus for semiconductor wafer
US5931719A (en) * 1997-08-25 1999-08-03 Lsi Logic Corporation Method and apparatus for using pressure differentials through a polishing pad to improve performance in chemical mechanical polishing
US5975998A (en) * 1997-09-26 1999-11-02 Memc Electronic Materials , Inc. Wafer processing apparatus
US6336845B1 (en) 1997-11-12 2002-01-08 Lam Research Corporation Method and apparatus for polishing semiconductor wafers
US5948699A (en) * 1997-11-21 1999-09-07 Sibond, L.L.C. Wafer backing insert for free mount semiconductor polishing apparatus and process
US5993302A (en) * 1997-12-31 1999-11-30 Applied Materials, Inc. Carrier head with a removable retaining ring for a chemical mechanical polishing apparatus
US6080050A (en) * 1997-12-31 2000-06-27 Applied Materials, Inc. Carrier head including a flexible membrane and a compliant backing member for a chemical mechanical polishing apparatus
US6531397B1 (en) 1998-01-09 2003-03-11 Lsi Logic Corporation Method and apparatus for using across wafer back pressure differentials to influence the performance of chemical mechanical polishing
US6020262A (en) * 1998-03-06 2000-02-01 Siemens Aktiengesellschaft Methods and apparatus for chemical mechanical planarization (CMP) of a semiconductor wafer
US6129610A (en) * 1998-08-14 2000-10-10 International Business Machines Corporation Polish pressure modulation in CMP to preferentially polish raised features
US6231428B1 (en) 1999-03-03 2001-05-15 Mitsubishi Materials Corporation Chemical mechanical polishing head assembly having floating wafer carrier and retaining ring
US6368189B1 (en) 1999-03-03 2002-04-09 Mitsubishi Materials Corporation Apparatus and method for chemical-mechanical polishing (CMP) head having direct pneumatic wafer polishing pressure
US6431968B1 (en) 1999-04-22 2002-08-13 Applied Materials, Inc. Carrier head with a compressible film
US6431959B1 (en) 1999-12-20 2002-08-13 Lam Research Corporation System and method of defect optimization for chemical mechanical planarization of polysilicon
KR100780099B1 (ko) * 2000-03-29 2007-11-29 신에쯔 한도타이 가부시키가이샤 연마용 워크지지반, 연마장치 및 연마방법
US6666756B1 (en) 2000-03-31 2003-12-23 Lam Research Corporation Wafer carrier head assembly
US20060180486A1 (en) * 2003-04-21 2006-08-17 Bennett David W Modular panel and storage system for flat items such as media discs and holders therefor
US11691241B1 (en) * 2019-08-05 2023-07-04 Keltech Engineering, Inc. Abrasive lapping head with floating and rigid workpiece carrier

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DD29614A (fr) *
US2565590A (en) * 1948-03-12 1951-08-28 Earl J Bullard Lapping machine
US3631634A (en) * 1970-01-26 1972-01-04 John L Weber Polishing machine
US3888053A (en) * 1973-05-29 1975-06-10 Rca Corp Method of shaping semiconductor workpiece
DE2608427A1 (de) * 1976-03-01 1977-09-08 Wacker Chemitronic Verfahren zum aufkitten von halbleiterscheiben
DE2712521A1 (de) * 1977-03-22 1978-09-28 Wacker Chemitronic Verfahren zum aufkitten von scheiben

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1014873B (de) 1953-01-13 1957-08-29 Hahn & Kolb Vorrichtung zum einseitigen Laeppen von Werkstuecken auf Laeppmaschinen
US3449870A (en) * 1967-01-24 1969-06-17 Geoscience Instr Corp Method and apparatus for mounting thin elements
US3603042A (en) * 1967-09-20 1971-09-07 Speedfam Corp Polishing machine
US3754359A (en) * 1970-09-16 1973-08-28 Spam D Avray Abrasion tools
US4020600A (en) * 1976-08-13 1977-05-03 Spitfire Tool & Machine Co., Inc. Polishing fixture
US4132037A (en) * 1977-02-28 1979-01-02 Siltec Corporation Apparatus for polishing semiconductor wafers

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DD29614A (fr) *
US2565590A (en) * 1948-03-12 1951-08-28 Earl J Bullard Lapping machine
US3631634A (en) * 1970-01-26 1972-01-04 John L Weber Polishing machine
US3888053A (en) * 1973-05-29 1975-06-10 Rca Corp Method of shaping semiconductor workpiece
DE2608427A1 (de) * 1976-03-01 1977-09-08 Wacker Chemitronic Verfahren zum aufkitten von halbleiterscheiben
DE2712521A1 (de) * 1977-03-22 1978-09-28 Wacker Chemitronic Verfahren zum aufkitten von scheiben

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
SOLID STATE TECHNOLOGY, Band 20, Oktober 1977, Long Island N.Y., A.C. BONORA "Flex-Mount Polishing of Silicon Wafers", Seiten 55 bis 58 * Seite 57, rechte Spalte unten, Seite 58 * *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6433935B2 (en) 1996-07-02 2002-08-13 Three-Five Systems, Inc. Display illumination system
US5980361A (en) * 1996-12-12 1999-11-09 Wacker Siltronic Gesellschaft Fur Halbleitermaterialien Ag Method and device for polishing semiconductor wafers
US6095898A (en) * 1997-10-30 2000-08-01 Wacker Siltronic Gesellschaft Fur Halbleitermaterialien Ag Process and device for polishing semiconductor wafers
US6404557B2 (en) * 1999-09-10 2002-06-11 Inviso, Inc. Display illumination system

Also Published As

Publication number Publication date
EP0004033B1 (fr) 1981-01-07
US4270316A (en) 1981-06-02
DE2809274A1 (de) 1979-09-13
DE2960114D1 (en) 1981-02-26
JPS54120490A (en) 1979-09-19

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