WO2018080797A1

WO2018080797A1 - Retainer ring

Info

Publication number: WO2018080797A1
Application number: PCT/US2017/056253
Authority: WO
Inventors: Qi Liu; Shin-Ichi Nakagawa; Yuki SHITANOKI; Bunichi Rai
Original assignee: E. I. Du Pont De Nemours And Company
Priority date: 2016-10-25
Filing date: 2017-10-12
Publication date: 2018-05-03

Abstract

The present invention relates to a retainer ring for chemical mechanical polishing (CMP). A method of manufacturing a retainer ring for CMP comprising steps of: preparing two or more of arc-shaped polishing parts comprising a non-thermoplastic polyimide resin composition, wherein each part comprises a polishing surface and a boding surface: setting the arc-shaped polishing parts at a bottom of a mold with the polishing surface facing to the bottom of the mold: and injecting a molten thermoplastic resin composition on the bonding surface of the arc-shaped polishing parts to form a holding layer.

Description

RETAINER RING

FIELD OF THE INVENTION

The invention relates to a retainer ring used in a machine for chemical-mechanical polishing (CMP).

BACKGROUND OF THE INVENTION

A CMP retianer ring is required to have sufficient wear resistance and an

inexpensive manufacturing cost.

US 6,471 ,566 discloses a retainer ring consisting of a retaining ring support and sacrificial retaining ring which consists of a plurality of capillary tube array units. The retaining ring support is constructed from metal or plastic. The capillary tube array unit is constructed from a material which has similar characteristic to those of the wafer (i.e., Silicon) or films typically present on the wafer. The sacrificial retaining ring is held down to a retaining ring support utilizing a fastener (e.g., a microscrews), an adhesive substance (e.g., Epoxy glue).

SUMMARY OF THE INVENTION

A first aspect of the present invention relates to a method of manufacturing a retainer ring for a chemical mechanical polishing device comprising steps of:

preparing two or more of arc-shaped polishing parts comprising a non-thermoplastic polyimide resin composition, wherein each part comprises a polishing surface and a boding surface: setting the arc-shaped polishing parts at a bottom of a mold with the polishing surface facing to the bottom of the mold: and

injecting a molten thermoplastic resin composition on the bonding surface of the arc- shaped polishing parts to form a holding layer.

A second aspect of the present invention relates to a retainer ring for a chemical mechanical polishing device comprising: two or more of arc-shaped polishing parts, wherein each part has a polishing surface and a boding surface; and a thermoplastic layer bonding to the bonding surface of the arc-shaped polishing parts,

wherein the arc-shaped polishing parts are made of a non-thermoplastic polyimide resin.

The present invention can provide a method of manufacturing a retainer ring that sufficiently withstands the wear for CMP at low cost. BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of this invention will be more readily understood from the following detailed description of the various aspects of the invention taken in conjunction with the accompanying drawings that depict various embodiments of the invention, in which:

FIG. 1 is a schematic diagram of a retainer ring;

FIG. 2 depicts a bottom view of a retainer ring; and

FIG. 3 explains a method of manufacturing a retainer ring. DETAILED DESCRIPTION OF THE INVENTION

The retainer ring is a generally circular ring with a hollow center, e.g. , a donut shape. A semiconductor wafer is polished inside the retainer ring such that the retainer ring maintains the semiconductor wafer in position. The retainer ring surrounds the periphery of thesemiconductor wafer and prevents the wafer from popping out of the holding head while polishing by rotating.

FIG. 1 shows side view of one example of the retainer ring. The retainer ring 100 comprises two or more of arc-shaped polishing parts 101 and a holding layer 103. The arc- shaped polishing parts 101 comprises a non-thermoplastic polyimide resin composition. The arc-shaped polishing parts 101 have a polishing surface 107 and a boding surface 105. The bonding surface faces to the holding layer 103. The holding layer comprises a thermoplastic polymer.

Outer diameter of the retainer ring is 100 to 1000 mm in an embodiment, 130 to 800 mm in another embodiment, 150 to 500 mm in another embodiment. Inner diameter of the retainer ring is 95 to 955 mm in an embodiment, 125 to 795 mm in another embodiment, 145 to 495 mm in another embodiment.

The holding layer 103 holds the arc-shaped polishing parts 101 . The arc-shaped polishing parts 101 are fixed to the holding layer 103 without any screw in an embodiment. The bonding surface side 105 of the arc-shaped polishing parts 101 are embedded in the holding layer 103 in another embodiment. The polishing surface 107 of the arc-shaped polishing parts 101 contact to a polishing pad. The arc-shaped polishing parts 101 are circularly aligned. The retainer ring 100 comprises 2 to 30 of the arc-shaped polishing parts 101 to form a circle in an embodiment, 7 to 25 in another embodiment, 15 to 20 in another embodiment. There are gaps 109 between the arc-shaped polishing parts 101 in an embodiment. The abrasive slurry can be discharged throught the gaps 109 during polishing. There is no gap between the arc- shaped polishing parts 101 in another embodiment. Line grooves to discharge the abrasive slurry can be formed on the polishing surface 107 in another embodiment.

The arc-shaped polishing parts 101 is 3 to 200 mm thick in an embodiment, 4 to 150 mm thick in another embodiment, 5 to 60 mm thick in another embodiment, 6 to 40 mm thick in another embodiment, 8 to 20 mm thick in another embodiment. The arc-shaped polishing parts 101 is 5 to 200 mm wide in an embodiment, 7 to 100 mm wide in another embodiment, 10 to 70 mm wide in another embodiment, 15 to 50 mm wide in another embodiment. The width of the arc-shaped polishing parts 101 can be approximately the difference between the outer diameter and the inner diameter of the retainer ring.

The holding layer 103 is a thermoplastic resin. The thermoplastic resin is selected from the group consisting of polyvinyl chloride, polystyrene, polyethylene, polyurethane, polyester, polyoxymethylene (POM), polyamide (PA), polycarbonate (PC), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethersulfone (PES),

polyphenylenesulfide (PPS), polyether ether ketone (PEEK), polyamide-imides (PAI), Polyetherimide (PEI), and a mixture thereof in an embodiment. The thermoplastic resin is selected from the group consisting of polyphenylenesulfide(PPS), polyether ether ketone (PEEK), polyamide-imides (PAI), and a mixture thereof in another embodiment. Glass transition temperature (Tg) of the thermoplastic resin is 50 to 350 °C in an embodiment, 65 to 300 °C in another embodiment, 72 to 250 °C in another embodiment, 80 to 180 °C in another embodiment. The softening temperature (Ts) of the thermoplastic resin is 80 to 300 °C in an embodiment. The melting temperature (Tm) of the thermoplastic resin is 1 10 to 390 °C in an embodiment, 150 to 375 °C in another embodiment, 200 to 350 °C in another embodiment.

The holding layer 103 is 5 to 100 mm thick in an embodiment, 10 to 70 mm thick in another embodiment, 20 to 50 mm thick in another embodiment. The holding layer 103 is 6 to 210 mm wide in an embodiment, 8 to 1 10 mm wide in another embodiment, 1 1 to 75 mm wide in another embodiment, 16 to 55 mm wide in another embodiment. The width of the holding layer 103 can be approximately the difference between the outer diameter and the inner diameter of the retainer ring.

The retainer ring 100 has gaps 109 between the arc-shaped polishing parts 101 in another embodiment as shown in FIG. 2. A slurry can be dispensed through the gaps 109 that allow a slurry to flow to inside or outside the retainer ring 100 where a semiconductor wafer is positioned. The gap 109 is 1 to 50 mm wide in an eimbodiment, 2 to 25 mm wide in another eimbodiment, 3 to 10 mm wide in another eimbodiment. The gap 109 is 0.5 to 150 mm high in an eimbodiment, 0.7 to 55 mm wide in another eimbodiment, 1 to 10 mm wide in another eimbodiment. The gaps 109 allow the slurry dispense to flow to the semiconductor wafer in an embodiment. In an embodiment, the polishing surface 107 can have grooves that can also allow the slurry dispense in the retainer ring. The outer diameter of the holding layer 103 is 2 to 5 mm larger than the circle of the arc-shaped polishing parts 101 in another embodiment as shown in FIG. 2.

A method of manufacturing a retainer ring is explained with reference to FIG. 3.

The arc-shaped polishing parts 101 are set on a bottom of a mold with the polishing surface 107 facing to the bottom 303 of a mold 301 . The mold separates into a first mold 301 and a second mold 305 in an embodiment. The first mold 301 could have concaves the arc-shaped polishing parts 101 fit in in another embodiment. The arc-shaped polishing parts 101 are placed at the bottom 303 of the cavity of the first mold 301 in another embodiment. The arc-shaped polishing parts 101 can be fixed at a desired place by vacume in an embodiment.

A molten thermoplastic resin is injected into the molds to form a holding layer over the bonding surface 105 of the arc-shaped polishing parts 101 . A sprue gate 307 the molten thermoplastic resin composition injected through can be equipped in the second mold 305 in an embodiment as shown in FIG. 3. The sprue gate 307 can be formed in either or both in the first mold 301 and/or the second mold 305 in another embodiment. The first mold and the second mold can be heated at 100 to 450 °C in an embodiment, 150 to 350 °C in another embodiment. The retainer ring is ejected after cooling down the injected resin.

Non-thermoplastic Polyimide Resin Composition

The arc-shaped polishing parts 101 comprise a non-thermoplastic polyimide resin composition. Non-thermoplastic polyimide resin is a polyimide comprising a 2-dimensional linear molecular structure but has no thermal melting property. Thermal melting property here means the reversible property of becoming fluid as the temperature rises above glass transition temperature (Tg), or melting point (Tm), and solidifying again as the temperature falls; non- thermoplastic polyimides are not heat-melting either because they do not exhibit a clear Tg or Tm, or because the Tg, or Tm is so high that the material exhibits

conspicuous thermal decomposition at or below these temperatures. The non- thermoplastic polyimide resin is used to describe a polyimide component that has a Tg greater than 280° C in an embodiment, greater than 350° C in another embodiment, and greater than 400° C in another embodiment, and no discernable Tg in temperatures up to at least 400° C in another embodiment.

The non-thermoplastic polyimide resin derives from a diamine and a dianhydride in an embodiment.

The diamine can be selected from the group consisting of m-phenylene diamine (MPD), p-phenylene diamine (PPD), 4,4'-oxydianiline (ODA), methylene dianiline (MDA) toluene diamine (TDA) and a mixture thereof in an embodiment. The diamine can be selected from the group consisting of m-phenylene diamine (MPD), p-phenylene diamine (PPD), 4,4'-oxydianiline (ODA) and a mixture thereof in another embodiment. The diamine is p-phenylene diamine (PPD) and m-phenylene diamine (MPD), in another embodiment.

The dianhydride can be a tetracarboxylic acid dianhydride in an embodiment. The dianhydride can be selected from the group consisting of benzophenone tetracarboxylic dianhydride (BTDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), trimellitic anhydride (TMA), pyromellitic dianhydride (PMDA), maleic anhydride (MA), nadic anhydride (NA) and a mixture thereof in another embodiment. The anhydride can be selected from the group consisting of pyromellitic dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) and a mixture thereof in another embodiment. The anhydride is 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) in another embodiment.

The non-thermoplastic polyimides may be derived from a combinations of anhydride and diamine selected from the group consisting of BTDA-MPD, TMA-MDA, BTDA-TDA- MPD, BTDA-MDA-NA, TMA-MPD, TMA-ODA, BPDA-ODA, BPDA-MPD, BPDA-PPD, BPDA-MPD-PPD, BTDA-4,4'-diaminobenzophenone, and BTDA-bis(p-phenoxy)-p,p'- biphenyl in an embodiment. The non-thermoplastic polyimide is derived from a

combination of diamine and at least one dianhydride of PMDA-ODA or BPDA-MPD-PPD in another embodiment. In another embodiment, the non- thermoplastic polymer can be the poly(BPDA-co(PPD; MPD)). The non-thermoplastic polyimide resin could be derived from at least a p-phenylene diamine (PPD) and a m-phenylene diamine (MPD) and 3, 3', 4,4'- biphenyltetracarboxylic dianhydride (BPDA) in another embodiment.

In one embodiment, the non-thermoplastic polyimide resin is prepared by reacting a diamine with a tetracarboxylic acid dianhydride.

The diamine can comprise a structure of:

H₂N-R'-NH₂

wherein R' is a divalent, aromatic radical in an embodiment.

The tetracarboxylic acid dianhydride can comprise a structure of: o o o o

\ / \ /

c c

wherein R is a tetravalent radical containing at least one ring of six carbon atoms characterized by benzenoid unsaturation, the four carboxyl groups of said dianhydride being attached directly to different carbon atoms in a ring of the R radical in an

embodiment.

The reaction temperature can be below 175 °C in an embodiment, below 100 °C in another embodiment, to form the polyamide acid. The formed polyamide acid is then converted to the polyimide while in solution by heating in the presence of tertiary amine which acts as a Lewis base in an embodiment. The tertiary amine can form the solvent for the polymerization reaction, or can form part of the solvent for the polymerization reaction or can be added after polymerization. The polyamide acid as a polyimide precursor becomes the corresponding polyimide when being heated or chemically treated.

In an embodiment, a polymer chain of the non-thermoplastic polyimide resin comprises a repeating unit represented by the following formula:

wherein Ri is a tetravalent aromatic radical having 1 to 5 benzenoid-unsaturated rings of 6 carbon atoms, the four carbonyl groups being directly bonded to different carbon atoms in a benzene ring of the Ri radical and each pair of carbonyl groups being bonded to adjacent carbon atoms in the benzene ring of the Ri radical; and R2 is a divalent aromatic radical having 1 to 5 benzenoid-unsaturated rings of carbon atoms, the two amino groups being directly bonded to different carbon atoms in the benzene ring of the R2 radical.

Structurally speaking, non-thermoplastic polyimides include wholly aromatic polyimides, which are polyimides in the narrow sense of the word, and these wholly aromatic polyimides are preferably non-thermoplastic polyimides in an embodiment. A wholly aromatic polyimide here is an aromatic polyimide that has an imide group directly bound to an aromatic ring, and that either contains no aliphatic carbon, or has no hydrogen directly bound to the carbon if such is present in an embodiment.

In an embodiment, the polyamide acid can be represented as a repeating unit of the following general formula, wherein the polyamide acid can be either a homopolymer or copolymer of two or more of the repeating units:

wherein R3 is a tetravalent aromatic radical having 1 to 5 benzenoid-unsaturated rings of 6 carbon atoms, the four carbonyl groups being directly bonded to different carbon atoms in a benzene ring of the R3 radical and each pair of carbonyl groups being bonded to adjacent carbon atoms in the benzene ring of the R3 radical; and R₄ is a divalent aromatic radical having 1 to 5 benzenoid- unsaturated rings of carbon atoms, the two amino groups being directly bonded to different carbon atoms in the benzene ring of the R₄ radical.

wherein R may be greater than about 60 to about 85 mole% PPD units and about 15 to about 40 mole% MPD units.

The term rigid polyimide is meant to connote that there are no flexible linkages in the polyimide unit.

In preparation of the aromatic polyimide compositions, the solution imidization process can be utilized according to the following in an embodiment. The diamines are generally first dissolved in a solvent to form the diamine component in the required concentration of the solvent; the dianhydride is added to the reaction solution in

substantially equimolar quantities to form a polyamide acid (PAA) polymer solution. A slight molar excess of either the dianhydride or diamine component may be possible. A molar excess of about 0.5 % to about 1 .0 % of the diamine component may be used.

The resulting PAA polymer solution can be transferred over a period of time to a heated solution of the solvent in an embodiment. The transferred PAA polymer solution can be continuously heated and agitated to complete the reaction of soluble PAA to a slurry of insoluble polyimide in an embodiment.

The resulting polyimide slurry may be washed with solvent and dried at about 100 to about 230 °C in an embodiment; at about 140 to about 190 °C in another embodiment; at about 150 to 180 °C in another embodiment to convert the polyimide slurry to a polyimide resin in the form of a powder having a high surface area. Depending on the particle size resulting from the precipitation of polyamide acid from the reaction solution, the particles of polyimide may be further modified for example, by suitable grinding techniques, to provide a desirable particle size for handling and subsequent molding.

The solvents that can be useful in the solution polymerization process for

synthesizing the PAA polymer solution can be the organic solvents whose functional groups will not react with either of the reactants (the BPDA or the diamines) to any appreciable extent in an embodiment. The solvent can exhibit a pH of about 8 to about 10 in an embodiment. The pH can be measured by mixing the solvent with a small amount of water and then measuring with pH paper or probe. Such solvents include, for example, pyridine and β-picoline in an embodiment. Of the solvents disclosed in U.S. Pat. No.

3,249,588 and 3, 179,614, pyridine (KB=1 .4X1 O^"9) can be a solvent for these reactants in the polymerization reaction as well as functioning as the catalyst in another embodiment. For a dianhydride and a diamine to react to form a PAA polymer solution, a basic catalyst can be needed in another embodiment. Since pyridine is a basic compound, it may function herein as both a catalyst and a solvent in another embodiment. The solvent can be present in a quantity such that the concentration of the PAA polymer solution can be about 1 wt% to about 15 wt% in an embodiment. In an

embodiment, the quantity may be from about 8 wt% to about 12 wt%.

The surface area for the non-thermoplastic polyimide resin powder may be at least about 20 m²/g in an embodiment, at least about 75 m²/g in another embodiment.

The non-thermoplastic polyimide resin composition comprising the non- thermoplastic polyimide resin powder made above is molded under elevated pressures to form the arc-shaped polishing parts. In another embodiment, the non-thermoplastic polyimide resin composition is molded at pressures of about 50,000 psi to about 100,000 psi (about 345 Mpa to about 690 Mpa) at an ambient temperature.

Tensile strength of the arc-shaped polishing parts is 30 to 280 MPa at 23 °C in an embodiment, 40 to 250 MPa at 23 °C in another embodiment, 50 to 200 MPa at 23 °C in another embodiment, 90 to 220 MPa at 23 °C in another embodiment, and 100 to 200 MPa at 23 °C in another embodiment. Tensile strength measures the force required to pull a something such as a structural beam to the point where it breaks. Tensile strength of a material is the maximum amount of tensile stress that it can take before failure, for example breaking. ASTM D1708 is available to measure the tensile strength.

Coefficient of friction (COF) of the arc-shaped polishing parts is

0.01 to 0.7 at PV=3.4 MPa m/sec in an embodiment, 0.03 to 0.68 at PV=3.4 MPa m/sec in another embodiment, 0.05 to 0.66 at PV=3.4 MPa m/sec in another embodiment, 0.07 to 0.64 at PV=3.4 MPa m/sec in another embodiment, 0.08 to 0.60 at PV=3.4 MPa m/sec in another embodiment, and 0.1 to 0.55 at PV=3.4 MPa m/sec in another embodiment. COF describes the ratio of the force of friction between two bodies and the force pressing them together. Coefficients of friction range from near zero to greater than one. ASTM G77 is available to measure the coefficient of friction.

Flexural strength of the arc-shaped polishing parts is 50 to 500 MPa at 23 °C in an embodiment, 65 to 450 MPa at 23 °C in another embodiment, 80 to 400 MPa at 23 °C in another embodiment, 150 to 350 MPa at 23 °C in another embodiment, 185 to 330 MPa at 23 °C in another embodiment, 190 to 300 MPa at 23 °C in another embodiment. Flexural strength, also known as bend strength, is a mechanical parameter for brittle material to define a material's ability to resist deformation under load. ASTM D790 is available to measure the flexural strength.

Flexural modulus of the arc-shaped polishing parts is 2000 to 8000 MPa at 23 °C in an embodiment, 2500 to 7500 MPa at 23 °C in another embodiment, 3000 to 7100 MPa at 23 °C in another embodiment, 3900 to 6900 MPa at 23 °C in another embodiment, 4500 to 6700 MPa at 23 °C in another embodiment, 4800 to 6500 MPa at 23 °C in another embodiment. Flexural modulus is the ratio of stress to strain in flexural deformation or the tendency for a material to bend. ASTM D790 is available to measure the flexural modulus.

Surface hardness (Rockwell E) of the arc-shaped polishing parts is at least 50 in an embodiment, 60 to 150 in another embodiment, 70 to 120 in another embodiment, 80 to 100 in anotehr embodiment. Specific gravity of the arc-shaped polishing parts is at least 1 .30 in an embodiment, 1 .35 to 1 .7 in another embodiment, 1 .38 to 1 .6 in another embodiment, 1 .4 to 1 .5 in anotehr embodiment. ASTM D792 is available to measure the specific gravity. For the non-thermoplastic polyimide resin, U.S. Pat. No. 3, 179,614; 3,249,588;

5,886, 129; 3, 179,631 ; and 4,360,626, can be incorporated herein by reference in its entirety.

The non-thermoplastic polyimide resins are commercially available from E. I. du Pont de Nemours and Company of Wilmington, DE, U.S.A. under the DuPont™ Vespel® brand, S grade of materials. Examples of DuPont™ Vespel® brand, S grade of materials include SP-1 , SP-3, SP-21 , SP-22, SP-21 1 , SP-214, SP-224, SP-2515, SCP-5000, SCP-5009, SCP-50094, and SCP-5050, which is suitable for the retainer ring described herein.

Claims

CLAIMS What is claimed is:

1 . A method of manufacturing a retainer ring for a chemical mechanical polishing device comprising steps of:

preparing two or more of arc-shaped polishing parts comprising a non-thermoplastic polyimide resin composition, wherein each part comprises a polishing surface and a boding surface:

setting the arc-shaped polishing parts at a bottom of a mold with the polishing surface facing to the bottom of the mold: and

2. The method of claim 1 , wherein the non-thermoplastic polyimide resin derives from a diamine and a dianhydride.

3. The method of claim 2, wherein the diamine is selected from the group consisting of m- phenylene diamine (MPD), p-phenylene diamine (PPD), 4,4'-oxydianiline (ODA), methylene dianiline (MDA) toluene diamine (TDA) and a mixture thereof. 4. The method of claim 2, wherein the dianhydride is selected from the group consisting of benzophenone tetracarboxylic dianhydride (BTDA), 3,3',4,

4'-biphenyltetracarboxylic dianhydride (BPDA), trimellitic anhydride (TMA), pyromellitic dianhydride (PMDA), maleic anhydride (MA), nadic anhydride (NA) and a mixture thereof.

5. The method of claim 1 , wherein tensile strength of the arc-shaped polishing parts is 30 to 280 MPa at 23 °C.

6. The method of claim 1 , wherein coefficient of friction (COF) of the arc-shaped polishing parts is 0.01 to 0.7 at PV=3.4 MPa m/sec.

7. The method of claim 1 , wherein flexural strength of the arc-shaped polishing parts is 50 to 500 MPa at 23 °C.

8. The method of claim 1 , wherein flexural modulus of the arc-shaped polishing parts is 2000 to 8000 MPa at 23 °C.

9. The method of claim 1 , wherein surface hardness (Rockwell E) of the arc-shaped polishing parts is at least 50.

10. The method of claim 1 , wherein specific gravity of the arc-shaped polishing parts is at least 1.30.

1 1 . The method of claim 1 , wherein a polymer chain of the non-thermoplastic polyimide resin comprises a repeating unit represented by the following formula:

12. The method of claim 1 , wherein the thermoplastic resin is selected from the group consisting of polyvinyl chloride, polystyrene, polyethylene, polyurethane, polyester, polyoxymethylene (POM), polyamide (PA), polycarbonate (PC), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethersulfone (PES),

polyphenylenesulfide(PPS), polyether ether ketone (PEEK), polyamide-imides (PAI), Polyetherimide (PEI), and a mixture thereof.

13. A retainer ring for a chemical mechanical polishing device comprising:

two or more of arc-shaped polishing parts, wherein each part has a polishing surface and a boding surface; and a thermoplastic layer bonding to the bonding surface of the arc-shaped polishing parts, wherein the arc-shaped polishing parts are made of a non-thermoplastic polyimide resin.