KR20050112113A - Diamond conditioning of soft chemical mechanical planarization/polishing(cmp) polishing pads - Google Patents

Abstract

Conditioning of chemical mechanical planarization (CMP) using conventional diamond-embedded abrasive strips are well suited to condition conventional "hard" polishing but not soft polishing pads because the diamonds not only remove waste material, but they also damage the polishing surface of the pad. Embodiments of the present invention condition soft polishing pads using diamond strips without damaging the soft polishing pad (108).

Description

DIAMOND CONDITIONING OF SOFT CHEMICAL MECHANICAL PLANARIZATION / POLISHING (CMP) POLISHING PADS}

Embodiments of the present invention relate to chemical mechanical planarization / polishing (CMP) and, more particularly, conditioning of CMP polishing pads.

Chemical mechanical planarization / polishing (CMP) is a process technology first developed in the mid-1980s to enable the production of integrated circuits on substrates or wafers. CMP processes are used in the preparation of wafers and in the fabrication of semiconductor devices or structures on wafers. The CMP process can be used to planarize (ie, flatten) the semiconductor layer on the wafer, the insulating layer on the semiconductor layer, and the conductive layer on the insulating layer of certain patterns.

Typical CMP systems include a wafer carrier and a platen mounted in a housing. The polishing pad is firmly attached to the platen and the wafer to be polished is firmly attached to the wafer carrier. A typical CMP process works as follows. The wafer carrier rotates the wafer and / or the platen rotates the polishing pad. A chemical slurry is applied to the surface of the polishing pad and the wafer is polished (or planarized) in contact with the polishing pad. The combination of chemical slurry application and mechanical rotation has led to the term "chemical mechanical planarization".

As the wafer is polished, chemical slurries and materials removed from the wafer tend to polish the surface of the polishing pad while smoothing the polishing pad and reducing the polishing rate and efficiency. It is therefore important that the polishing pad surface is clean and free of surface irregularities. The process of cleaning the polishing pad is sometimes referred to as "conditioning" or "refreshing."

One way to condition the polishing pads is to rub them with a conventional diamond-embedded polishing disk or strip. Although conventional diamond embedded abrasive strips are quite suitable for conditioning "hard" polishing pads used for rough polishing, they are not suitable for conditioning "soft" polishing pads used for precise polishing. When a soft polishing pad is conditioned with a diamond embedded abrasive disk, the diamonds not only remove excess material, but also damage the polishing surface of the pad.

In the drawings, like reference numerals generally indicate the same, functionally similar, and / or structurally equivalent elements. The drawing in which a given element first appears is indicated by the leftmost digit of the reference number.

1 is a schematic diagram of a CMP polishing system according to an embodiment of the present invention.

2 is a flow chart illustrating a process performed by a CMP polishing system in accordance with embodiments of the present invention.

3 illustrates an exemplary soft polishing pad in accordance with an embodiment of the present invention.

4 illustrates the operation of a conditioning arm in accordance with an embodiment of the present invention.

5 illustrates a diamond conditioner according to an embodiment of the present invention.

1 is a schematic diagram of a CMP polishing system 100 in accordance with an embodiment of the present invention. The CMP polishing system includes a housing 101, a polishing head 102, a control panel 103, a platen 104, a spindle 105, a wafer 106, base 107, soft polishing pad 108, conditioning arm 110, diamond (or artificial diamond) conditioner 112, slurry tank 114, spindle 115, water tank ( 116, and electromechanical equipment 118. Slurry tank 114 and / or water tank 116 may be located in housing 101 or separately from housing. Electromechanical equipment 118 includes vertical drivers, rotational drivers, controllers, or other equipment commonly used to operate arms, motors, and other devices of CMP polishing systems. can do.

The platen 104 may be mounted to the housing 101 and rotated by a motor (not shown) in the electromechanical equipment 118. The polishing head 102 may be mounted to the spindle 105 and rotated by a motor (not shown) in the electromechanical equipment 118. Wafer 106 is mounted away from polishing head 102 with the surface to be polished down. The soft polishing pad 108 is mounted to the platen using an adhesive. During polishing of the wafer 106, the polishing head 102 may be rotated in the opposite direction to the rotation of the polishing pad 108, as shown by arrows 120 and 122. Alternatively, the polishing head 102 can rotate while the platen 104 is stopped. Alternatively, the polishing head 102 may be stationary while the platen 104 is rotating. Slurry tank 114 delivers the slurry to the surface of soft polishing pad 108 during wafer 106 polishing.

The conditioning arm 110 pivots at its base 107 when conditioning the soft polishing pad 108. A motor (not shown) in the electromechanical equipment 118 may move the conditioning arm 110. During conditioning of the soft polishing pad 108, the water tank 116 can supply a rinsing solution, such as drinking water or de-ionized (DI) water, to the surface of the soft polishing pad 108.

2 is a flow chart illustrating a process 200 performed by a CMP polishing system 100 in accordance with embodiments of the present invention. Machine readable media having machine readable instructions may be used to cause the processor to perform the process 200. Of course, process 200 is merely an example process and other processes may be used. Exemplary process 200 may be used to remove metal, oxides, glass, silicon, and the like. Although the exemplary process 200 has been described with respect to wafers, the exemplary process 200 may be semiconductors, memory disks, or other suitable objects that require flatness, planarity, precise polishing, and the like, such as lenses and mirrors. Can be used.

In block 202, the slurry from the slurry tank 114 is applied to the surface of the soft polishing pad 108 and the head 102 moves the wafer 106 when the platen 104 applies a force to the wafer 106. To hold and rotate the wafer 106 relative to the soft polishing pad 108. In block 204, the head 102 separates the wafer 106 in contact with the soft polishing pad 108 and stops the slurry from flowing to the surface of the soft polishing pad 108.

In block 206, the soft polishing pad 108 is conditioned using a diamond conditioner 112. In one embodiment of the invention, the platen 104 rotates the soft polishing pad 108, and the rinse liquid from the water tank 116, for example, deionized water to the surface of the soft polishing pad 108. Rinse the soft polishing pad 108 by supplying, and the conditioning arm 110 with the diamond conditioner 112 moves (eg, back and forth) across the soft polishing pad 108. Although the polishing of the soft polishing pad 108 is described as being performed in an 'ex situ' (between the wafers 106 polishing) in some embodiments, in other embodiments the polishing of the soft pad 108 may be performed. Polishing may be performed 'in situ' (while the wafers 106 are being polished), or in any desired combination of the two. Of course, the soft polishing pad 108 may be conditioned in accordance with embodiments of the present invention prior to polishing any wafers 106.

Process for conditioning the soft pad 108 using the diamond conditioner 112 to ensure that the conditioning arm 110 with the diamond conditioner 112 does not destroy the soft polishing pad 108 or significantly reduce its life. One or a combination of the following process parameters can be modified to improve the In fact, in accordance with embodiments of the present invention, the life of the soft polishing pad 108 is significantly increased. The increased lifetime of the soft polishing pad 108 not only saves labor and parts costs, but also improves processes (eg, the soft polishing pads 108 do not need to be replaced often).

In one embodiment, the conditioning arm 110 applies 0.25 psi to the soft polishing pad 108 via a diamond conditioner 112 as opposed to approximately 3 psi applied when using conventional hard polishing pad techniques.

In known soft polishing pad conditioning methods, the platen and soft polishing pad do not rotate. In embodiments of the present invention, the rotation speed of the platen 104 and soft polishing pad 108 may be approximately 100 revolutions per minute (100 (rpm)).

In known soft polishing pad conditioning methods, deionized water may not flow into the soft polishing pad. In one embodiment of the invention, the deionized water flow rate from the deionized water tank 116 may be 1 gallon per minute (gpm). Alternatively, the flow rate can be any value between 0 and approximately 7 gallons per minute.

In known soft polishing pad conditioning methods, no diamond conditioner is used, so that no downward force is applied to the soft polishing pad. In one embodiment, the downward force applied by the diamond conditioner 112 to the soft polishing pad may be 0.25 psi.

In known soft polishing pad conditioning methods, a diamond conditioner is not used. In known hard polishing pad conditioning methods, the diamond conditioner sweeps at least 10 times. In one embodiment, diamond conditioner 112 is swept once across the soft polishing pad.

3 illustrates an exemplary soft polishing pad 108 in accordance with one embodiment of the present invention. Exemplary soft polishing pad 108 may be made of napped poromerics-porous urethane layers, including several pores and on a mylar or compressible urethane substrate. . In an alternative embodiment, the exemplary soft polishing pad 108 may be a soft pad made of tangled polyester fibers coated with polyurethane. In yet another embodiment, the exemplary soft polishing pad 108 may be a felt sheet of fibers containing micro porous elastomer. Alternatively, the exemplary soft polishing pad 108 may be a porous thermoplastic resin matrix, typically polyurethane, reinforced with a fibrous network, such as a felt mat of polyester fibers. matrix). Examples of suitable soft pads may include any of the Politex®Series soft pads from Rodel Holdings, Wilmington, Delaware.

Soft polishing pad 108 according to embodiments of the present invention includes relatively porous and non-compressive fine porous polyurethane polishing pads when compared to other types of polishing pads and polyurethane containing felt polishing pads. It will be distinguished from known hard polishing pads. Examples of hard pads include SUBA 1000 Series polishing pads and SUBA®Pads from Rodel, Phoenix, Arizona.

4 illustrates the operation of a conditioning arm 110 in accordance with an embodiment of the present invention. When the soft polishing pad 108 is moving and the wafer 106 is being polished, the conditioning arm 110 (and the diamond conditioner 112) stays at a location 402 adjacent to the periphery of the soft polishing pad 108. After a predetermined number of wafers have been polished by the soft polishing pad 108, or when the polishing rate is reduced due to the accumulation of slurry and other debris, the conditioning arm 110 is pivoted at one end by the base 107. , Lowered over the soft polishing pad 108, and from the position 402 to another of the periphery of the soft polishing pad 108 across the surface of the soft polishing pad 108 (as shown by phantom lines). Sweep along an arc, indicated by arrows 408, to a second position 406 adjacent to the piece (also indicated by phantom lines).

5 illustrates a diamond conditioner 112 according to an embodiment of the present invention. Diamond conditioner 112 includes a base 502 with diamonds 504. Base 502 is any suitable rigid substrate. Diamonds 504 may be artificial diamonds, natural diamonds, or the like.

Diamonds 504 may be disposed over base 502 using chemical vapor deposition (CVD). Alternatively, the diamonds 504 may be embedded in the base 502. For example, diamond conditioner 112 may be formed by embedding diamond particles in nickel coated on the surface of a rigid substrate in accordance with known or patented techniques.

Embodiments of the invention may be implemented using hardware, software, firmware, or a combination of hardware and software. In implementations using software, the software may be stored in a computer program product (such as an optical disk, magnetic disk, floppy disk, etc.) or a program storage device (such as an optical disk drive, magnetic disk drive, floppy disk drive, etc.).

The above description of the illustrated embodiments of the invention is not intended to be exhaustive or to limit the invention to the precise form disclosed. As will be appreciated by those skilled in the art, specific embodiments and examples of the invention have been described herein for illustrative purposes, but various equivalent modifications are possible within the scope of the invention. Such modifications may be made to the invention in light of the above detailed description.

In the above description, numerous specific details, such as specific processes, materials, devices, and the like, are set forth in order to provide a thorough understanding of embodiments of the present invention. However, one skilled in the art will recognize that embodiments of the present invention may be practiced without one or more specific details or with other methods, components, and the like. In other instances, well-known structures or operations are not shown or described in detail to avoid obscuring the understanding of this description.

Various operations have been described as a number of individual operations that are performed in turn in a manner that is most helpful in understanding embodiments of the present invention. However, the order in which they are described should not be construed to imply that such operations are necessarily order dependent or to imply that the operations are performed in the order presented.

Reference throughout this specification to “one embodiment” or “an embodiment” includes any specific feature, structure, process, block, or characteristic described in connection with the embodiment in at least one embodiment of the invention. It means. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places in the specification are not necessarily all referring to the same embodiment. Moreover, certain features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

The terms used in the following claims should not be construed as limiting the invention to the specific embodiments disclosed in the specification and the claims. Rather, the scope of embodiments of the present invention is to be determined solely by the following claims and should be construed in accordance with established claim interpretations.

Claims (17)

A method for conditioning a chemical mechanical planarization (CMP) polishing pad, Conditioning a soft polishing pad using a diamond conditioner. The method of claim 1, Rotating the soft polishing pad on a platen; Rinsing the soft polishing pad; And Passing a diamond conditioner over the soft polishing pad. The method of claim 2, Applying zero pounds per square inch (psi) from the platen to the soft polishing pad. The method of claim 1, Passing a conditioning arm with the diamond conditioner over the soft polishing pad comprises passing the diamond conditioner over the soft polishing pad during wafer polishing. The method of claim 1, Passing a conditioning arm with the diamond conditioner over the soft polishing pad comprises passing the diamond conditioner over the soft polishing pad between wafer polishings. The method of claim 1, Rotating the wafer relative to the soft polishing pad. The method of claim 6, And applying a slurry to the surface of the soft polishing pad. A chemical mechanical planarization (CMP) system, A head mounted in a housing; A wafer mounted on the head; A platen mounted on the housing; A soft polishing pad mounted on the platen; A pad conditioning arm mounted on the housing; And Diamond conditioner mounted on the pad conditioning arm Chemical mechanical planarization (CMP) system comprising a. The method of claim 8, And a slurry tank mounted to the housing. The method of claim 9, And a water tank mounted to the housing. The method of claim 8, Further comprising electromechanical equipment mounted to the housing. A chemical mechanical planarization (CMP) device, A soft polishing pad attached to the platen of the housing; And A pad conditioning arm mounted to the housing, wherein a diamond conditioner is attached to the pad conditioning arm CMP device comprising a. The method of claim 12, And the soft polishing pad comprises napped poromerics-porous urethane layers on a substantially compressible substrate. The method of claim 13, And the soft polishing pad comprises brushed poromerix-porous urethane layers on a mylar substrate. The method of claim 12, And the soft polishing pad comprises brushed poromerix-porous urethane layers on a substantially compressible urethane substrate. The method of claim 12, Wherein the diamond conditioner comprises a diamond strip. The method of claim 12, And the diamond strip comprises artificial diamonds embedded in a base.