Apparatus and method of controlling the temperature of polishing pads used in planarizing micro-device workpieces
Temperature regulation systems and methods for controlling the temperature of polishing pads used in planarizing micro-device workpieces are disclosed herein. In one embodiment, an apparatus for polishing a workpiece includes a platen defining a planarizing zone and a primary duct system. The platen can have a first duct, and the primary duct system can have a second duct operatively coupled to the first duct of the platen. The second duct is configured to direct a gas flow laterally relative to the planarizing zone. The apparatus also includes a pad support carried by the primary duct system, and a polishing pad carried by the pad support. The pad support can have a plurality of apertures that are in fluid communication with the gas flow in the second duct.
Latest Micron Technology, Inc. Patents:
- Vertical Transistor, Integrated Circuitry, Method Of Forming A Vertical Transistor, And Method Of Forming Integrated Circuitry
- SEMICONDUCTOR DEVICE HAVING CONTACT PLUG
- Integrated Assemblies and Methods of Forming Integrated Assemblies
- APPARATUSES AND METHODS FOR SINGLE-PASS ACCESS OF ECC INFORMATION, METADATA INFORMATION OR COMBINATIONS THEREOF
- APPARATUSES AND METHODS FOR INPUT BUFFER DATA FEEDBACK EQUALIZATION CIRCUITS
The present invention relates to planarizing and polishing micro-device workpieces including mechanical and chemical-mechanical planarization. In particular, the present invention relates to controlling the temperature of the polishing pad during the planarizing cycle.
BACKGROUND Mechanical and chemical-mechanical planarization processes (collectively “CMP”) remove material from the surface of micro-device workpieces in the production of microelectronic devices and other products.
The carrier head 30 has a lower surface 32 to which a micro-device workpiece 12 may be attached, or the micro-device workpiece 12 may be attached to a resilient pad 34 under the lower surface 32. The carrier head 30 may be a weighted, free-floating carrier head, or an actuator assembly 36 may be attached to the carrier head 30 to impart rotational motion to the micro-device workpiece 12 (indicated by arrow J) and/or to reciprocate the micro-device workpiece 12 back and forth (indicated by arrow I).
The planarizing pad 40 and a planarizing solution 44 define a planarizing medium that mechanically and/or chemically-mechanically removes material from the surface of the micro-device workpiece 12. The planarizing solution 44 may be a conventional CMP slurry with abrasive particles and chemicals that etch and/or oxidize the surface of the micro-device workpiece 12, or the planarizing solution 44 may be a “clean” non-abrasive planarizing solution without abrasive particles. In most CMP applications, abrasive slurries with abrasive particles are used on non-abrasive polishing pads, and clean non-abrasive solutions without abrasive particles are used on fixed-abrasive polishing pads.
To planarize the micro-device workpiece 12 with the CMP machine 10, the carrier head 30 presses the micro-device workpiece 12 face-downward against the planarizing pad 40. More specifically, the carrier head 30 generally presses the micro-device workpiece 12 against the planarizing solution 44 on a planarizing surface 42 of the planarizing pad 40, and the platen 20 and/or the carrier head 30 moves to rub the micro-device workpiece 12 against the planarizing surface 42. As the micro-device workpiece 12 rubs against the planarizing surface 42, the planarizing medium removes material from the face of the micro-device workpiece 12.
The planarity of the finished micro-device workpiece surface is a function of the distribution of planarizing solution under the micro-device workpiece during planarization, the chemical reaction rate, the relative velocity between the polishing pad and the micro-device workpiece surface, and several other factors. Some of these factors are temperature-dependent, such as the chemical reaction rate. Accordingly, it can be difficult to achieve a planar micro-device workpiece surface because often the temperature varies across the workpiece surface during planarization. For example, often the relative velocity between the micro-device workpiece surface and the rotating polishing pad is different across the micro-device workpiece surface, consequently creating a temperature gradient. The temperature gradient can generate different chemical reaction rates in the planarizing solution and, accordingly, different polishing rates across the micro-device workpiece that result in a non-planar micro-device workpiece surface.
It is, accordingly, desirable to control the temperature of the planarizing pad to stabilize the temperature-dependent factors that affect the planarity of the micro-device workpiece surface. Previously, attempts have been made to control the temperature by circulating a cooling liquid in the platen. This approach, however, has several disadvantages. It is difficult and expensive to manufacture a liquid system for rotary platens. Liquid systems, for example, require rotary fluid couplings to connect the platen to an external heat exchanger. Liquid systems also require extensive maintenance to prevent leaking and failure of the moving parts. In addition to maintenance expenses, significant downtime may be required to replace or repair rotary couplings or other components. Such significant downtime disrupts production and reduces the throughput of CMP processing.
SUMMARYThe present invention relates to controlling the temperature of a polishing pad during planarizing and/or polishing of micro-device workpieces. In one embodiment, an apparatus for polishing a workpiece includes a platen defining a planarizing zone and a primary duct system. The platen can have a first duct, and the primary duct system can have a second duct operatively coupled to the first duct of the platen. The second duct is configured to direct a gas flow laterally relative to the planarizing zone. The apparatus also includes a pad support carried by the primary duct system, and a polishing pad carried by the pad support. The pad support can have a plurality of apertures that are in fluid communication with the gas flow in the second duct. As a result, the temperature of the gas flow affects the temperature of the polishing pad to control the temperature at the pad/workpiece interface.
In another embodiment, an apparatus for planarizing a micro-device workpiece includes a polishing pad having a planarizing surface for planarizing the micro-device workpiece, a pad support carrying the polishing pad, and a duct system carrying the pad support. The duct system has a duct with at least one inlet and at least one outlet. The duct is configured to direct a gas flow proximate to the pad support in a direction generally parallel to the planarizing surface.
In another embodiment, an apparatus for gas-cooling and/or gas-heating a polishing pad includes a platen having a duct system defined by a plurality of channels configured to receive a gas flow, a pad support carried by the platen, and a polishing pad carried by the pad. The pad support is positioned proximate to the plurality of channels so that the gas flow can cool or heat the pad. The polishing pad has a polishing surface for polishing a micro-device workpiece.
An embodiment of a temperature control system for use with a platen includes a duct system configured for attachment to the platen, and a pad support carried by the duct system. The duct system has at least one inlet, at least one outlet, and at least one duct coupled to the inlet and the outlet. The duct is configured to direct a gas flow under the pad support to control the temperature of the pad.
An embodiment of a method for controlling the temperature of a polishing pad includes causing a gas to flow through a duct system under a polishing pad, and maintaining a desired temperature of the polishing pad with the gas flow. Another embodiment includes flowing gas into a duct system between a polishing pad and a platen, and exhausting the gas from the duct system.
BRIEF DESCRIPTION OF THE DRAWINGS
The following disclosure is directed to polishing or planarizing machines and methods for controlling the temperature of polishing pads related to mechanical and/or chemical-mechanical planarization of micro-device workpieces. The term “micro-device workpiece” is used throughout to include substrates upon which and/or in which microelectronic devices, micromechanical devices, data storage elements, and other features are fabricated. For example, micro-device workpieces can be semiconductor wafers, glass substrates, insulative substrates, or many other types of substrates. Furthermore, the terms “planarization” and “planarizing” mean either forming a planar surface and/or forming a smooth surface (e.g., “polishing”). Several specific details of the invention are set forth in the following description and in
In the illustrated embodiment, the pad support 250 has an upper surface 252 attached to a backside 244 of the planarizing pad 240, and a lower surface 254 carried by the duct system 260. The pad support 250 can be stiff to provide support to the planarizing pad 240 during the planarizing process. The pad support 250, for example, can be a relatively thin sheet of polymeric material or organic material. In one embodiment, the pad support 250 is composed of FR-4, commonly used as a sub-pad in CMP applications.
The pad support 250 can also include a plurality of apertures 251 to facilitate heat transfer between the planarizing pad 240 and the gas flowing through the duct system 260. Each aperture 251 extends from the lower surface 254 of the pad support 250 to the upper surface 252. In other embodiments, the apertures 251 might not extend completely through the pad support 250, or the pad support 250 might not have apertures. The apertures 251 in the pad support 250 can be arranged in patterns that provide the desired heat transfer rates across the backside 244 of the planarizing pad 240.
Referring to
The duct system 260 includes a plurality of ducts 273 that channel the gas to the apertures 251 under the planarizing pad 240. The duct system 260 can also provide a continuous flow of gas under the planarizing pad 240 to maintain a desired heat transfer rate. For example, a gas flow “A” can enter the ducts 273 through openings 268, flow through the ducts 273, and then be exhausted through a central port 266.
An advantage of several of the embodiments discussed above is the ability to control or regulate the temperature of the polishing pad during planarization. Controlling the temperature throughout the polishing pad provides better control of the chemical reaction rate throughout the pad and, consequently, results in control of the planarized surface on the micro-device workpiece. Furthermore, the gas flow temperature control systems are less expensive and easier to maintain than liquid control loops. For example, several embodiments of gas duct systems are less susceptible to downtime for leaks compared to liquid cooling systems because they do not need rotary liquid couplings. Furthermore, air can leak through portions of the platen without creating contamination concerns. Another advantage of many of the embodiments discussed above is that they can be used by retrofitting existing planarizing machines. For example, duct systems can be inserted between polishing pads and platens on existing planarizing machines.
From the foregoing, it will be appreciated that specific embodiments of the invention have been described herein for purposes of illustration, but that various modifications may be made without deviating from the spirit and scope of the invention. Accordingly, the invention is not limited except as by the appended claims.
Claims
1-55. (canceled)
56. A method for controlling the temperature of a polishing pad, comprising:
- causing a gas flow through a duct system under a polishing pad; and
- maintaining a desired temperature of the polishing pad with the gas flow.
57. The method of claim 56 wherein causing a gas flow comprises forcing gas to move through the duct system by coupling the duct system to a vacuum or a blower.
58. The method of claim 56 wherein causing a gas flow comprises flowing the gas in apertures in a pad support.
59. The method of claim 56 wherein causing a gas flow comprises moving gas through a duct extending through a platen.
60. The method of claim 56 wherein causing a gas flow comprises moving gas through a duct extending through the polishing pad.
61. The method of claim 56 wherein causing a gas flow comprises flowing gas radially through the duct system.
62. The method of claim 56 wherein causing a gas flow comprises driving gas into the duct system by rotating ducts with curved walls.
63. The method of claim 56, further comprising flowing the gas flow through a heat exchanger.
64. The method of claim 56, further comprising changing the temperature of the pad.
65. The method of claim 56 wherein maintaining a desired temperature comprises changing the temperature of the gas.
66. The method of claim 56 wherein maintaining a desired temperature comprises changing the flow rate of the gas.
67. A method for controlling the temperature of a polishing pad, comprising:
- rotating a platen having a plurality of channels;
- causing a gas flow through at least some of the plurality of channels;
- passing the gas flow at least proximate to the pad; and
- regulating the temperature of the pad by controlling the temperature or flow rate of the gas.
68. The method of claim 67 wherein causing a gas flow comprises forcing gas to move through the plurality channels by coupling the plurality of channels to a vacuum or a blower.
69. The method of claim 67 wherein causing a gas flow comprises moving the gas through a duct extending through the platen.
70. The method of claim 67 wherein passing the gas flow comprises flowing the gas in apertures in a pad support.
71. The method of claim 67, further comprising flowing the gas flow through a heat exchanger.
72. The method of claim 67 wherein causing a gas flow comprises flowing the gas through a duct extending through the pad and a pad support.
73. A method for controlling the temperature of a polishing pad, comprising:
- flowing gas into a duct system between a polishing pad and a platen; and
- exhausting the gas from the duct system.
74. The method of claim 73 wherein flowing gas comprises forcing gas to move through the duct system by coupling the duct system to a vacuum or a blower.
75. The method of claim 73 wherein flowing gas comprises passing gas through a duct extending through the platen.
76. The method of claim 73, further comprising moving the gas proximate to the polishing pad to change the temperature of the polishing pad.
77. The method of claim 73 wherein flowing gas comprises passing the gas in apertures in a pad support.
78. The method of claim 73 wherein flowing gas comprises moving gas through a duct extending through the polishing pad.
79. The method of claim 73 wherein flowing gas comprises flowing gas radially through the duct system.
80. The method of claim 73 wherein flowing gas comprises driving gas into the duct system by rotating ducts with curved walls.
81. The method of claim 73, further comprising flowing the gas through a heat exchanger.
82. The method of claim 73, further comprising changing the temperature of the pad.
83. The method of claim 73, further comprising changing the temperature of the gas.
84. The method of claim 73, further comprising changing the flow rate of the gas.
85. A method for cooling the temperature of a polishing pad, comprising:
- moving gas in an inlet and into a channel;
- passing the gas through the channel and proximate to a pad support;
- cooling the pad support with the passing gas; and
- reducing the temperature of the polishing pad coupled to the pad support.
86. The method of claim 85, further comprising flowing gas through a duct extending through a platen.
87. A method for planarizing a micro-device workpiece with a temperature control, comprising:
- pressing the micro-device workpiece against a pad;
- imparting relative motion between the micro-device workpiece and the pad;
- causing a gas flow through a duct system under the pad; and
- regulating the temperature of the pad by controlling the temperature and/or flow rate of the gas.
88. The method of claim 87 wherein causing a gas flow comprises flowing gas in apertures in a pad support.
89. The method of claim 87 wherein causing a gas flow comprises flowing gas radially through the duct system.
Type: Application
Filed: Nov 7, 2006
Publication Date: Mar 8, 2007
Applicant: Micron Technology, Inc. (Boise, ID)
Inventors: Theodore Taylor (Boise, ID), Larry Birch (Nampa, ID), Freddie Dunn (Boise, ID)
Application Number: 11/594,496
International Classification: B24B 49/00 (20060101);