US20070026772A1

US20070026772A1 - Apparatus for use in processing a semiconductor workpiece

Info

Publication number: US20070026772A1
Application number: US11/191,385
Authority: US
Inventors: Kert Dolechek; Raymon Thompson
Original assignee: Semitool Inc
Current assignee: Semitool Inc
Priority date: 2005-07-28
Filing date: 2005-07-28
Publication date: 2007-02-01

Abstract

The present invention provides a chuck for receiving and supporting a semiconductor workpiece for processing. The chuck includes a body for supporting the workpiece. The body is porous or has a plurality of openings, apertures or channels. A compressible corrosion resistant member is disposed around the outer periphery of the supporting body. The chuck includes a means for evacuating air from the pores or plurality of openings, apertures or channels in the body to create a vacuum. In operation, a workpiece is placed onto the supporting body. The device side of the workpiece is preferably placed on the compressible corrosion resistant member. Upon evacuating the air (or other gas) from the pores or openings in the supporting body, a vacuum is created, drawing the workpiece toward the supporting body. A seal is created and maintained between the device side of the workpiece and the compressible corrosion resistant member. Consequently, the entire backside of the workpiece is exposed for processing while at the same time the device side of the workpiece is protected from any potentially damaging process fluids. By exposing the backside of the workpiece to a chemical etchant, semiconductor workpieces can be thinned to a desired thickness.

Description

TECHNICAL FIELD

The present invention relates to an apparatus for handling a workpiece, such as a semiconductor wafer, flat panel display, rigid disk or optical media, thin film heads or other workpieces formed from a substrate on which microelectronic circuits, data storage elements or layers, or micro-mechanical elements may be formed. These and similar articles are collectively referred to herein as a “wafer” or “workpiece.” Specifically, the present invention relates to a chuck for use in handling, processing and treating semiconductor workpieces.

BACKGROUND OF THE INVENTION

State of the art electronics (e.g., cellular phones, personal digital assistants, and smart cards) demand thinner integrated circuit devices (“ICD”). In addition, advanced packaging of semiconductor devices (e.g., stacked dies or “flip-chips”) provide dimensional packaging constraints which require an ultra-thin die. Moreover, as operating speeds of ICDs continue to increase heat dissipation becomes increasingly important. This is in large part due to the fact that ICDs operated at extremely high speeds tend to generate large amounts of heat. That heat must be removed from the ICD to prevent device failure due to heat stress and to prevent degradation of the frequency response due to a decrease in carrier mobility. One way to enhance thermal transfer away from the ICD, thereby mitigating any deleterious temperature effects, is by thinning the semiconductor wafer from which the ICD is fabricated. Other reasons for thinning the semiconductor wafer include: optimization of signal transmission characteristics; formation of via holes in the die; and minimization of the effects of thermal coefficient of expansion between an individual semiconductor device and a package.
Semiconductor wafer thinning techniques have been developed in response to this ever increasing demand for smaller, higher performance ICDs. Typically, semiconductor devices are thinned while the devices are in wafer form. Conventional wafer thicknesses vary depending on the size of the wafer. For example, the thickness of a 150 mm diameter silicon semiconductor wafer is typically about 650 microns, while wafers having a diameter of 200 mm are generally about 725 microns thick, and 300 mm wafers generally have a thickness of 775 microns. Mechanical grinding of the back side of a semiconductor is one standard method of thinning wafers. Such thinning is referred to as “back grinding.” Generally, the back grinding process employs methods to protect the front side or device side of the semiconductor wafer. Conventional methods of protection of the device side include the application of a protective tape or a photoresist layer to the device side of the wafer. The back side of the wafer is then ground until the wafer reaches a desired thickness.
However, conventional back grinding processes have drawbacks. Mechanical grinding induces stress in the surface and edge of the wafer, including micro-cracks and edge chipping. This induced wafer stress can lead to performance degradation and wafer breakage resulting in low yield. In addition, there is a limit to how much a semiconductor wafer can be thinned using a back grinding process. For example, semiconductor wafers having a conventional thickness (as mentioned above) can generally be thinned to a range of approximately 250-150 microns.
Accordingly, it is common to apply a wet chemical etch process to a semiconductor wafer after it has been thinned by back grinding. This process is commonly referred to as polishing. The polishing process relieves the induced stress in the wafer, removes grind marks from the back side of the wafer and results in a relatively uniform wafer thickness. Additionally, polishing after back grinding thins the semiconductor wafer beyond conventional back grinding capabilities. For example, utilizing a wet chemical etch process after back grinding allows standard 200 and 300 mm semiconductor wafers to be thinned to 100 microns or less. Wet chemical etching typically includes exposing the back side of the wafer to an oxidizing agent (e.g., HNO₃, H₃PO₄, H₂SO₄) or alternatively to a caustic solution (e.g., KOH, NaOH, H₂O₂). Examples of wet chemical etching processes may be found in co-pending U.S. patent application Ser. No. 10/631,376, assigned to the assignee of the present invention. The teachings of patent application Ser. No. 10/631,376 are incorporated by reference.
Although methods for thinning semiconductor wafers are known, they are not without limitations. For example, mounting a semiconductor wafer to a submount or “chuck” (as it is commonly known) so that the wafer can be thinned requires expensive coating and bonding equipment and materials, increased processing time, and the potential for introducing contaminates into the process area. Additionally, adhesives for bonding a wafer to a chuck that may be useful in a mechanical grinding process will not withstand the chemical process fluids used in wet chemical etching. Furthermore, the current use of a photoresist or adhesive tape fails to provide mechanical support for very thin wafers either during the back grind process or in subsequent handling and processing. The use of tape also creates obstacles in the removal process. For example, tape removal may subject a wafer to unwanted bending stresses. In the case of a photoresist, the material is washed off the device side of a wafer with a solvent, adding to the processing time and use of chemicals, and increasing the risk of contamination.
Further, thinned semiconductor wafers are prone to warping and bowing. And because thinned semiconductor wafers can be extremely brittle, they are also prone to breakage when handled during further processing. Thinned semiconductor wafers (e.g., below 250 microns) also present complications in automated wafer handling because, in general, existing handling equipment has been designed to accommodate standard wafer thicknesses (e.g., 650 microns for 150 mm wafer and 725 microns for 200 and 300 mm wafers).
Accordingly there is a need for equipment to secure a semiconductor workpiece for thinning, while at the same time reducing the number of processing steps necessary for thinning the semiconductor workpiece.

SUMMARY OF THE INVENTION

The present invention provides an apparatus for use in processing semiconductor workpieces. The apparatus allows for the entire back side of a workpiece to be thinned, yet prevents damage to the device side of the workpiece. The process and equipment of the present invention produces thinned wafers having a thickness less than about 125 microns, while reducing the number of processing steps. This results in, among other things, improved process efficiency, improved yields and a broader range of product applications.
In one aspect, the present invention provides a chuck for receiving and supporting a semiconductor workpiece for processing. The chuck includes a porous body for supporting the workpiece. The porous body has a compressible corrosion resistant member disposed around its outer periphery. The chuck includes a means for evacuating air from the porous body to create a vacuum. In operation, a workpiece is placed onto the supporting body. The exclusion zone (i.e., an area having a radial width of approximately 1-5 mm around the outer periphery of the workpiece) of the device side of the workpiece is preferably placed on the compressible corrosion resistant member. Upon evacuating the air (or other gas) from the porous supporting body, a vacuum is created, drawing the workpiece toward the supporting body. Depending on the strength of the vacuum created and/or the compressibility of the corrosion resistant member, the device side of the workpiece is drawn against the supporting body (or in close proximity to the supporting body). A seal is created and maintained between the device side of the workpiece and the compressible corrosion resistant member. Consequently, the entire backside of the workpiece is exposed for processing while at the same time the device side of the workpiece is protected from any potentially damaging process fluids. By exposing the backside of the workpiece to a chemical etchant, semiconductor workpieces can be thinned to thicknesses of less than 150 microns or even less than 100 microns, resulting in a wider range of product applications.
The means for evacuating air (or other gas) from the porous body can include various different configurations in the present invention. For example, a poppet valve located in a cavity in the bottom side of the porous body can be used to evacuate air from the porous body to create a vacuum. Alternatively, a diaphragm and compression assembly connected to the bottom of the porous body can be utilized. Or a pump, either connected directly to the porous body, or connected to a process vessel housing the chuck and workpiece, can be used to evacuate air from the porous body and create the desired vacuum.
In another aspect of the present invention, the chuck includes a body for supporting a workpiece for processing. The body includes either a plurality of openings that extend through the body or a channel formed in the surface of the body. A compressible corrosion resistant member is attached to the outer periphery of the body. Alternatively, a retainer may be removably connected to an outer edge of the body. The compressible corrosion resistant member is attached to the retainer. Means for evacuating air (or other gases) from the openings or the channel is provided as described above to create a vacuum, securing the workpiece to the chuck and leaving the entire back side of the workpiece exposed for thinning or other processing.
In yet another aspect of the invention, the chuck is comprised of an upper body removeably connected to a lower body. A cavity or opening is formed between the upper and lower bodies. At least two openings, and preferably a plurality of openings, extend through the upper body of the chuck and is in fluid communication with the cavity. A compressible corrosion resistant member is attached to the upper body at its outer periphery. The chuck is provided with means for evacuating gas from the cavity and the openings to create a vacuum (as described in the preceeding paragraphs). As a result of the vacuum, the workpiece is drawn towards the upper body and forms a seal with the compressible member. This seal protects microelectronic components formed on the device side of the workpiece from potentially damaging process fluids, resulting in improved manufacturing efficiencies.
Any of the described aspects of the invention may be combined and/or repeated one or more times to achieve optimal results. The invention resides as well in sub-combinations of the aspects described. These and other objects, features and advantages of this invention are evident from the following description of preferred embodiments of this invention, with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an embodiment of the present invention.
FIG. 2 is a partial, enlarged view of FIG. 1, showing a compressible member shaped generally as a modified O-ring gasket.
FIG. 3 is a partial, enlarged, cross-sectional view of the present invention, showing an alternate embodiment of the present invention where a compressible member is shaped generally as a hoop gasket.
FIG. 4 is a partial, enlarged view of FIG. 1, showing the arrangement of a valve, porous body and retainer.
FIG. 5 is a cross-sectional view of an embodiment of the present invention.
FIG. 6 is a partial, enlarged view of FIG. 5, showing a compressible member shaped generally as a tapered gasket.
FIG. 7 is a partial enlarged view of an embodiment the present invention, showing a compressible member shaped generally as a tapered gasket and having a diameter relative larger than that depicted in FIG. 6.
FIG. 8 is a partial enlarged view of an embodiment of the present invention, showing a compressible member shaped generally as a lip style gasket.
FIG. 9 is a partial enlarged view of an embodiment of the present invention, showing a compressible member shaped generally as a trapezoid gasket.
FIG. 10 is a partial enlarged view of an embodiment of the present invention, showing a compressible member shaped generally as a hollow, rectangular gasket.
FIG. 11 is a cross-sectional view of an embodiment of the present invention, showing a chuck comprising a channel to secure the workpiece to the chuck.
FIG. 12 is a partial, enlarged view of FIG. 11.
FIG. 13 is a partial, enlarged view of an embodiment of the present invention, showing a chuck comprising a compressible member shaped generally as a tongue gasket and further comprising a channel to secure the workpiece to the chuck.
FIG. 14 is a partial, enlarged view of an embodiment of the present invention, showing a chuck having a compressible member shaped generally as a hoop gasket and further comprising a channel to secure a workpiece to the chuck.
FIG. 15 is a cross-sectional view of an embodiment of the present invention, showing a chuck comprising an upper body removably engaged to a lower body.
FIG. 16 is a partial, enlarged view of FIG. 15, showing the cooperation among the upper body, the lower body and the workpiece.
FIG. 16 is a partial, enlarged, cross-sectional view of the present invention, showing an alternate embodiment of the present invention.
FIG. 17 is a partial, enlarged view of FIG. 15, showing in detail a valve for use in the present invention.
FIG. 18 is a cross-sectional view of an embodiment of the present invention, showing a chuck comprising an upper body removably engaged to a lower body.
FIG. 19 is a partial, enlarged view of the embodiment shown in FIG. 18.
FIG. 20 is a cross-sectional view of an embodiment of the present invention, showing a chuck comprising an upper body removably engaged to a lower body and further comprising an engagement seal.
FIG. 21 is a partial, enlarged view of the embodiment shown in FIG. 20.
FIG. 22 shows an embodiment of an engagement seal.
FIG. 23 is a cross-sectional view of an embodiment of the present invention, showing a chuck comprising a single body with at least two channels on an upper surface of the body
FIG. 24 is a partial, enlarged view of the embodiment shown in FIG. 23.
FIG. 25 is a cross-sectional view of an embodiment of the present invention, showing a chuck comprising a fluted body with a peripheral channel at about its periphery.
FIG. 26 is a cross-sectional view of another embodiment of the present invention, showing a chuck comprising a fluted body with a peripheral channel at about its periphery.

DETAILED DESCRIPTION

While this invention is susceptible of embodiments in many different forms, and will herein be described in detail, preferred embodiments of the invention are disclosed with the understanding that the present disclosure is to be considered as providing exemplifications of the principles of the invention and are not intended to limit the broad aspects of the invention to the embodiments disclosed or illustrated.
With reference generally to FIGS. 1-10, there is shown a chuck 10 for supporting a workpiece 20 having a device side 30 and a back side 40. The chuck 10 is comprised of a porous body 50 for supporting the workpiece 20 and has an annular recess 55 formed at the outer periphery of the body 50. A compressible, corrosion resistant member 80 is disposed in the annular recess 55. The chuck 10 includes means for evacuating air (or other gases, for example nitrogen) 100 from the inner volume of the porous body 50 to create a vacuum.
In operation, the workpiece 20 is placed onto the supporting porous body 50. As commonly known to those of skill in the art, the workpiece 20 includes an exclusion zone, i.e., an area having a radial width of approximately 1-5 mm around the outermost periphery of the workpiece. The workpiece 20 is placed device side 30 down with the exclusion zone resting on the compressible corrosion resistant member 80. Upon evacuating the air (or other gas) from the porous supporting body 50, a vacuum is created, drawing the workpiece 20 toward the supporting body 50. A seal is created and maintained between the device side 30 of the workpiece and the compressible corrosion resistant member 80. Depending on the strength of the vacuum created and/or the compressibility of the corrosion resistant member 80, the device side 30 of the workpiece 20 is drawn against the supporting body 50, or at least in close proximity to the supporting body 50. Consequently, the entire back side 40 of the workpiece 50 is exposed for processing and the device side 30 of the workpiece is protected from any potentially damaging process fluid.
The means for evacuating air (or other gas) 100 from the porous body 50 can include various different configurations in the present invention. For example, as shown in FIGS. 1, 4, 5, 15 and 17 the means for evacuating air or other gas 100 comprises a poppet valve engaged in a recess formed in the bottom of the porous body 50 opposite the workpiece 20. In another embodiment illustrated in FIGS. 26 and 27, the means for evacuating air or other gas 100 from the porous body 50 comprises a diaphragm 310 and compression assembly 315 connected to the bottom of the porous body 50. In yet another embodiment, a vacuum pump, either connected directly to the porous body 50, or connected to a process vessel that houses the chuck 10, can be used to evacuate air or other gas from the internal volume of the porous body 50. These means for evacuating air or other gas 100 will be described in greater detail below.
As shown in FIGS. 1-14, the chuck 10 also includes a retainer 60 removeably connected to the porous body 50 along the outer periphery 51 of the porous body 50. Preferably, the retainer wraps around the outer periphery 51 of the porous body 50 and engages the compressible member 80. As shown in FIG. 2, the retainer 60 may further comprise a peripheral flange or shoulder 70, which acts to align the workpiece 20 and prevent the workpiece 20 from sliding off of the chuck 10. Alternatively, as shown in FIGS. 3, 6, 7, 9 and 12-14, the retainer 60 engages an outer portion 81 of the compressible member 80 and an inner portion 82 of the compressible corrosion resistant member 80 includes a peripheral flange or shoulder 70 for aligning the workpiece. When properly aligned, the body 50 and compressible member 80 support the entire device side of the workpiece during processing.
Suitable materials for use in the chuck 10 components according to the present invention will now be discussed. Generally, the chuck 10 can be made from a number of different polymer or ceramic materials that are stable and highly chemically resistant. Preferably the porous body 50 comprises a ceramic material, which is known to be tough and durable. Porous ceramics are generally inert and can be produced with very consistent and uniform pore structures. Alternatively, the porous body 50 may comprise a thermoplastic polymer such as polyethylene, polypropylene or polytetrafluoroethylene having a plurality of channels, openings or apertures therein to render the body 50 essentially porous.
The retainer 60 preferably comprises a chemical resistant thermoplastic, e.g., a fluoropolymer such as polyvinylidene fluoride sold by Atofina Chemicals under the KYNAR tradename. In order to enhance the attachability of the retainer 60 to the supporting porous body 50, it is preferred that the retainer 60 be formed from a material having a Durometer hardness less than that of the Durometer hardness of the material comprising the porous body 50.
The compressible member 80 preferably comprises an elastomeric material selected from the group consisting of fluoroelastomer such as Viton (commercially available from DuPont), a perfluoroelastomer such as Kalrez (commercially available from DuPont) or Chemraz (commercially available from Greene Tweed), silicone, perfluorinated hydrocarbons such as tetrafluoromethane and hexafluorethane, chloroprene or neoprene, ethylene propylene diene terpolymer, nitrile rubber or Buna-N, copolymers of tetrafluoroethylene and propylene such as Aflas (commercially available from Asahi Glass) or Fluoraz (commercially available from Greene Tweed), epichlorohydrin copolymer or Hydrin rubber (commercially available from BF Goodrich), as well as blends of these materials. As illustrated in FIGS. 1, 2, 15, 16, 18, 19, 23, 24, 26 and 27, the compressible member 80 is preferably shaped like an “O-ring,” but it is contemplated that other shapes can be used as well (e.g., as shown in FIGS. 3 and 5-14).
Referring specifically to FIGS. 5-7, the chuck 10 of the present invention includes a compressible corrosion resistant member 80 having the general shape of a tapered gasket. This embodiment comprises a mechanical engagement seal 160 that aids in securing the workpiece 20 to the chuck 10. As shown in FIG. 6, the mechanical engagement seal 160 is formed by pressing a small ridge 170 of the compressible member 80 with sufficient force so as deform the ridge 170 and create a single contact line that seals and holds the workpiece 20 to the chuck 10. This seal prevents process fluid from migrating to the device side of the workpiece 20 and damaging the microelectronic components formed thereon. In addition to the engagement seal 160, means for evacuating air or other gas 100 from the porous body 50 to create a vacuum and maintain the workpiece adjacent to or against the porous body 50 is a poppet valve 110 as is commonly understood in the industry. Referring to FIG. 4, a poppet valve 110 generally comprises a valve head 120 with an opening 130 through which a vacuum may be drawn. The poppet valve 110 is prevented from being detached from the chuck 10 by having the diameter of its valve seat 140 larger than the diameter of the aperture 150 upon which the valve head 120 rests. Additional compressible members 80 sealably engage the poppet valve 110 to the porous body 50. The compressible corrosion resistant member 80 illustrated in FIGS. 5 and 6 also includes a retaining ridge 90, which like the peripheral flange 70 described above, acts to properly align the workpiece 20 and prohibit process fluid from damaging the device side 30 of the workpiece 20.
FIGS. 8-10 illustrate alternative embodiments of the present invention wherein the compressible corrosion resistant member 80 has the general shape of a lip-style gasket (FIG. 8), a trapezoid-shaped gasket (FIG. 9) or a bowed gasket having opposite anchors secured in recesses formed in the retainer 60 (FIG. 10). FIGS. 11-14 also illustrate various alternative configurations of the compressible corrosion resistant member 80 and recesses in the retainer 60 and body 50 for securing the compressible member 80. The compressible member 80 in each of these embodiments preferably comprises an elastomeric material as described above. Although not shown, the alternative embodiments illustrated in FIGS. 7-10 each comprise means for evacuating air or other gas 100 from the porous supporting body 50 to create a vacuum and secure the workpiece 20 to the chuck 10.
Turning to FIGS. 1-3 and 5-13, in order to secure the retainer 60 to the porous body 50, the porous body 50 includes an engagement member 55 and the retainer 60 includes a recess 65 configured to accept the engagement member 55 and removably connect the retainer 60 to the body 50. It is also within the scope of the present invention to include a retainer 60 with an engagement member 55 that engages a recess 65 in the porous body 50 to removably connect the retainer 60 to the body 50.
FIGS. 15-17 illustrate yet another embodiment of a chuck 10 according to the present invention. The chuck 10 comprises an upper body 190 removably engaged to a lower body 200. A cavity 220, or a plurality of cavities 220, is formed between the upper and lower bodies 190, 200. A circular channel 180 formed in an upper surface 210 of the upper body 190 and extending from the outer periphery to the center of the upper body 190 is connected to a means for evacuating air (or other gas) from the channel 100. The means for evacuating air 100 creates a vacuum and secures the workpiece to the upper surface 210 of the chuck 10. The means for evacuating air 100 disclosed in FIGS. 15-17 is a poppet valve 110, as is commonly known in the art. As explained above, and with reference to FIG. 17, the poppet valve 110 comprises a valve head 120 and a valve seat 140. Two compressible members 80 assist in sealing the valve 100 to the lower body 200 of the chuck 10. Each of these compressible members 80 preferably comprises an elastomeric material as described above.
An annular compressible member 80 is disposed within an annular recess 230 in the outer periphery of the upper body 190. Upon evacuating air from the channel 180, a vacuum is created, sealing the device side of the workpiece 20 against the compressible member 80. The upper body 190 and the lower body 200 may each comprise any of the materials identified above for the retainer 60, and preferably both comprise polyvinylidene fluoride. The upper body 190 and lower body 200 are connected by a pin 205 positioned within an aperture in the upper and lower bodies 190, 200. Alternatively (but not shown), the upper and lower bodies 190, 200 may be removeably connected via a corresponding engagement member and recess configuration as explained above. In order to facilitate removal of the upper body 190 from the lower body 200, a compressible member or O-ring gasket 80 acts as an interface between the mating surfaces of the upper and lower bodies 190, 200. The compressible member or O-ring gasket 80 is disposed in an annular recess 230 in the lower body 200 and preferably comprises an elastomeric material as described above.
FIG. 18 shows yet another embodiment of the present invention where the chuck 10 comprises an upper body 190 removably engaged to a lower body 200. Each body preferably comprises, as described above, a thermoplastic polymer, and even more preferably comprises polyvinylidene fluoride. The embodiment shown in FIG. 18 further comprises a circular channel 180 on an upper surface 210 of the upper body 190 extending from the outer periphery of the upper body 190 to the center of the upper body 190. When engaged, the upper body 190 and lower body 200 define a plurality of cavities 220 in the chuck 10. Preferably, the channel 180 is in fluid communication with at least one of the cavities 220. Means for evacuating air or other gas 100 from at least one of the cavities 220 in fluid communication with channel 180 may comprise any one of: a poppet valve 110, a vacuum pump, or a diaphragm and compression assembly. In operation, the vacuum created by the means for evacuating 100 maintains the workpiece adjacent to the channelized upper surface 210 of the upper body, while creating a seal between the compressible member 80 and the workpiece.
FIG. 19 is a partial, enlarged view of FIG. 18, showing the cooperation among the upper body 190, the lower body 200 and the workpiece 20. In this embodiment a compressible member 80 also extends between the upper body 190 and lower body 200 in aperture 230 to facilitate attachment and removal between the upper and lower bodies 190, 200. Both members 80 preferably comprise an elastomeric material as described above. A pin 205 secures the upper body 190 to the lower body 200 and may comprise any suitable corrosion resistant material and is preferably a screw, and even more preferably is a shoulder screw.
FIG. 20 shows another embodiment of the present invention where the chuck 10 comprises an upper body 190 removably engaged to a lower body 200. Each body comprises a material as described above. The embodiment shown in FIG. 20 comprises a plurality of openings or apertures 185. The openings or apertures 185 are in fluid communication with the cavity 220 defined by the engagement of the upper body 190 and lower body 200. A vacuum pump (not shown) is used to evacuate air or other gas from the cavity 220 and, hence, the plurality of openings. The evacuation of air or other gas creates a vacuum seal as described above. In addition to the vacuum seal, the embodiment disclosed in FIG. 20 also includes an engagement seal 160, which aids in securing the workpiece 20 to the chuck 10. The engagement seal 160 is more fully illustrated in FIG. 21 wherein the seal 160 is disposed within the upper body 190 and in FIG. 22 wherein the seal 160 is disposed within compressible corrosion resistant member 80.
FIG. 23 shows yet another embodiment of the present invention where the chuck 10 comprises a single body 260 with a channel 180 formed on an upper surface 270 of the single body 260. As shown in FIGS. 23 and 24, a compressible member 80 is disposed in an aperture 230 located at the outer periphery of the single supporting body 260. A vacuum pump (not shown) evacuates air or other gas from the channel 180 creating a vacuum seal with the workpiece 20 as described above with respect to FIG. 20. The single body 260 comprises a thermoplastic polymer, preferably polytetrafluoroethylene.
FIGS. 25 and 26 are cross-sectional views of an embodiment of the present invention where the chuck 10 comprises a supporting body 280 with a peripheral channel 290 at its periphery 300. The peripheral channel 290 contains a compressible member 80. The supporting body 280 comprises any material identified above for the retainer 60. A plurality of openings 185 extend through the thickness of the supporting body 280 (i.e., from the top surface 282 to the bottom surface 282). A diaphragm 310 is attached to the bottom of the supporting body 280. The engagement of the supporting body 280 and the diaphragm 310 define a cavity 220 in which a compression assembly 320 is disposed. The compression assembly 320 includes a helical spring 330 and a compression bar 340. With reference specifically to FIG. 25, the compression bar 340 has a cross-section that resembles generally a “U” shape. One end 350 of the helical spring 330 abuts a side 360 of the supporting body 280 that is proximate to the cavity 220, and a second (opposite) end 370 of the helical spring 330 abuts a side 380 of the compression bar 340 that is proximate to the cavity 220.
In operation, the diaphragm 310 is compressed on its side 400 that is distal from the compression bar 340 with sufficient force to compress the compression assembly 320, including the helical spring 330, to evacuate substantially and preferably completely the gaseous and liquid contents of the cavity 200 out through the one or more openings 185. The workpiece 20 is then placed on the supporting body 280 (device side down) that is distal from the compression assembly 320. When the compression assembly 320 is allowed to expand, a vacuum is created in the chuck 10 such that the workpiece 20 is held in place, exposing the back side of the workpiece 20 for thinning or other processing.
While embodiments and applications of the present invention have been shown and described, it will be apparent to one skilled in the art that other modifications are possible without departing from the inventive concepts herein. The invention, therefore, is not to be restricted except by the following claims and their equivalents.

Claims

1. A chuck for supporting a semiconductor workpiece having a back side and a device side, the chuck comprising:

a porous body for supporting the device side of the workpiece, the porous body having a compressible member attached at an outer periphery thereof;

means for evacuating air from the porous body to create a vacuum, the vacuum maintaining the workpiece adjacent to porous body and forming a seal between the compressible member and the workpiece.

2. The chuck of claim 1, wherein the porous body comprises a material selected from the group consisting of polyethylene, polypropylene, polytetrafluoroethylene, and ceramic.

3. The chuck of claim 1, wherein the compressible member comprises an elastomeric material selected from the group consisting of fluoroelastomers, perfluoroelastomers, silicone, perfluorinated hydrocarbons, chloroprene, ethylene propylene diene terpolymer, nitrile rubber, copolymers of tetrafluoroethylene and propylene, epichlorohydrin copolymer, and blends thereof.

4. The chuck of claim 1, wherein the means for evacuating air from the porous body comprises a poppet valve located in a cavity in a bottom side of the porous body.

5. The chuck of claim 1, wherein the means for evacuating air from the porous body comprises a diaphragm and compression assembly connected to a bottom side of the porous body.

6. The chuck of claim 1, wherein the means for evacuating air from the porous body comprises a pump.

7. The chuck of claim 1, further comprising a retainer connected to the porous body.

8. The chuck of claim 7, wherein the retainer engages the compressible member.

9. The chuck of claim 7, wherein the retainer wraps around the periphery of the chuck.

10. The chuck of claim 7, wherein the retainer comprises a thermoplastic polymer.

11. The chuck of claim 10, wherein the thermoplastic polymer is a fluoropolymer.

12. The chuck of claim 1, wherein the compressible member includes a shoulder for receiving the periphery of the workpiece.

13. A chuck for supporting a semiconductor workpiece, the chuck comprising:

a body for supporting the workpiece;

a plurality of openings extending through body;

a retainer connected to an outer edge of the body, the retainer having a compressible member attached thereto;

means for evacuating air from the openings in the body to create a vacuum, the vacuum maintaining the workpiece against the body and forming a seal between the compressible member in the retaining ring and the workpiece.

14. The chuck of claim 13, wherein the body has a semiconductor workpiece support surface having a step formed therein to center the semiconductor workpiece on the workpiece support surface.

15. The chuck of claim 13, wherein the workpiece has a back side and a device side and the body supports the entire device side of the workpiece.

16. The chuck of claim 13, wherein the compressible member is comprised of a corrosion resistant material.

17. The chuck of claim 13, wherein the retainer comprises an engagement member and the body comprises a recess configured to accept the engagement member and engage the retainer to the body.

18. The chuck of claim 13, wherein the body comprises an engagement member and the retainer comprises a recess configured to accept the engagement member and engage the retainer to the body.

19. A chuck for supporting a semiconductor workpiece having a back side and a device side, the chuck comprising:

a body for supporting the workpiece;

a plurality of openings extending through the body;

a compressible member attached to the body;

means for evacuating air from the openings in the body to create a vacuum, the vacuum maintaining the workpiece against the body and forming a seal between the compressible member and the workpiece.

20. A chuck for supporting a semiconductor workpiece having a back side and a device side, the chuck comprising:

an upper body removeably connected to a lower body,

a cavity formed between the upper and lower bodies;

a channel formed in a surface of the upper body, the channel being in fluid communication with the cavity;

a compressible member attached to the upper body; and

means for evacuating air from the cavity and the channel in the surface of the upper body to create a vacuum, the vacuum maintaining the workpiece adjacent the surface of the upper body and forming a seal between the compressible member and the workpiece.

21. The chuck of claim 20, further comprising a second compressible member positioned between the upper body and the lower body.

22. The chuck of claim 20, wherein a plurality of cavities is formed between the upper and lower bodies.

23. The chuck of claim 20, further comprising a pin for connecting the upper body and the lower body.

24. The chuck of claim 20, wherein the seal is formed between the compressible member and the device side of the workpiece.

25. The chuck of claim 20, wherein the upper body and the lower body are formed from a corrosion resistant thermoplastic polymer.

26. The chuck of claim 25, wherein the corrosion resistant thermoplastic polymer is polyvinylidene fluoride.

27. The chuck of claim 25, wherein the corrosion resistant thermoplastic polymer is polytetrafluoroethylene.