Securing mechanism and method for wafer bonder

Disclosed are various features associated with a securing mechanism for a wafer bonder. In certain situations, operation of securing mechanisms can generate undesirable particles and debris, and some them can be introduced to a wafer being bonded. In certain implementations, a securing mechanism can be configured to reduce the likelihood of such particles and debris being introduced to the wafer.

BACKGROUND

The present disclosure generally relates to the field of semiconductor wafer processing technology, and more particularly, to a securing mechanism for a wafer bonding device.

2. Description of the Related Art

In certain processing operations involving thin and/or fragile wafers, it may be desirable to mount a wafer to a plate for support and easier handling. Such a mounting process is sometimes referred to as a bonding process, and can be achieved by, for example, using an adhesive.

In certain bonding processes, a wafer joined to a plate can be cured application heat. During such application of heat, it is generally desirable to apply uniform mechanical pressure so that the wafer and the plate become bonded in a generally parallel manner.

SUMMARY

In certain implementations, the present disclosure relates to an apparatus for bonding a wafer to a plate. The apparatus includes a base member having a receiving side dimensioned to receive a wafer and a plate that are configured to be bonded. The apparatus further includes a lid having first and second opposing sides and configured to be placed in an open position and a closed position relative to the base member. The open position facilitates positioning of the wafer and the plate on the base member for bonding and removing of the bonded assembly of wafer and plate from the base member after the bonding. The closed position facilitates the bonding of the wafer and the plate. The first side is dimensioned to engage the receiving side of the base member when the lid is in the closed position. The apparatus further includes one or more securing mechanisms. Each securing mechanism is configured to engage and apply a securing force on the second side of the lid from the second side of the lid when the lid is in the closed position to thereby push the lid against the receiving side of the base member.

In certain embodiments, the lid can include a solid plate between the first and second side of the lid. The receiving side of the base member and the first side of the lid can define a bonding chamber when the lid is in the closed position.

In certain embodiments, the lid can be configured so as to substantially separate the bonding chamber from the second side of the lid. The lid can further include a diaphragm disposed on the lid's first side. The diaphragm can be dimensioned and configured to provide a bonding force to the wafer and the plate during the bonding. The lid can include a pressure pathway between a portion of its first side and a location behind the diaphragm. The pressure pathway can allow gas pressure to be provided to the location to allow the diaphragm to provide the bonding force. The receiving side of the base member can define a pressure pathway configured to receive gas from a source and in communication with the pressure pathway of the lid so as to provide the gas pressure to the location behind the diaphragm. The base member can further include a suction opening in communication with a suction source. The suction opening can be disposed so as to hold the assembly of wafer and plate during the bonding.

In certain embodiments, the base member can further include first and second seals disposed on the receiving side. The first seal can be configured to provide a gas seal between the outside and the pressure pathway of the base member. The second seal can be configured to provide a gas seal between the pressure pathway of the base member and the bonding chamber.

In certain embodiments, the securing mechanism can include a clamping device mounted to a mounting structure that is coupled to the base member. The clamping device can have a push rod configured to engage and push against the second side of the lid with one of its ends to provide the securing force.

The mounting structure can be positioned at a location outside the periphery of the base member and the periphery of the lid when the lid is in the closed position.

In certain embodiments, the securing mechanism can further include a support beam configured to couple the push rod to the mounting structure. The support beam can be further configured to position the push rod to a location that is within the periphery of the lid when the lid is in the closed position. The push rod and the support beam can be configured so as to allow adjustment of the push rod's length from the support beam to the end that engages the second side of the lid.

In certain embodiments, the securing mechanism can further include a locking handle configured to engage and lock the support beam when the push rod is providing the securing force to the second side of the lid. The locking handle can be configured to lock the support beam by a camming action.

In certain implementations, the present disclosure relates to a wafer bonding station having one or more of the apparatus summarized above.

In certain implementations, the present disclosure relates to a method for bonding a wafer to a plate. The method includes applying an adhesive between a wafer and a plate so as to form an assembly of the wafer and the plate. The method further includes positioning the assembly on a bonding area. The method further includes positioning a lid over the bonding area. The lid has an outside surface and an inside surface that is configured to facilitate application of pressure to the assembly. The method further includes applying a pushing force on the outside surface of the lid from the outside surface side of the lid so as to secure the lid in a substantially fixed orientation. The pushing force is directed along a direction having a component that is perpendicular to a plane defined by the wafer. The method further includes bonding the assembly by applying pressure and heat to the assembly.

In certain embodiments, the method can further include removing the pushing force on the outside surface of the lid upon completion of the bonding so as to allow the lid to be removed from the bonding area.

In certain implementations, the present disclosure relates to a device for securing a lid of a wafer bonding apparatus. The device includes a base coupled to a support structure of the wafer bonding device and disposed at a location that is outside the lid's periphery when the lid is in a closed position. The device further includes a support beam having a first end pivotably mounted to the base so as to allow the support beam to be placed in a disengagement position and an engagement position. The device further includes a push rod having an axis and mounted to the support beam at a mounting location on the support beam such that the push rod extends from the mounting location to a pushing end by a length at an angle relative to the support beam. The mounting location and the first end of the support beam are separated by a distance. At least one of the length, the angle, and the distance is selected so that when the support beam is in the engagement position, the pushing end of the push rod engages an upper surface of the lid in its closed position with the push rod's axis being less than approximately 20 degrees from a normal to a plane defined by the upper surface of the lid. The device further includes a locking mechanism configured to lock and unlock the support beam in and from, respectively, the engagement position.

In certain embodiments, the push rod's axis can be less than approximately 5 degrees from the normal.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

Provided herein are various methodologies and devices for processing wafers such as semiconductor wafers.FIG. 1shows an example of a process10where a functional wafer is further processed to form through-wafer features such as vias and back-side metal layers. As further shown inFIG. 1, the example process10can include bonding of a wafer to a carrier for support and/or to facilitate handling during the various steps of the process, and debonding of the wafer from the carrier upon completion of such steps.FIG. 1further shows that such a wafer separated from the carrier can be further processed so as to yield a number of dies.

In the description herein, various examples are described in the context of GaAs substrate wafers. It will be understood, however, that some or all of the features of the present disclosure can be implemented in processing of other types of semiconductor wafers. Further, some of the features can also be applied to situations involving non-semiconductor wafers.

In the description herein, various examples are described in the context of back-side processing of wafers. It will be understood, however, that some or all of the features of the present disclosure can be implemented in front-side processing of wafers.

In the process10ofFIG. 1, a functional wafer can be provided (block11).FIG. 2Adepicts a side view of such a wafer30having first and second sides. The first side can be a front side, and the second side a back side.

FIG. 2Bdepicts an enlarged view of a portion31of the wafer30. The wafer30can include a substrate layer32(e.g., a GaAs substrate layer). The wafer30can further include a number of features formed on or in its front side. In the example shown, a transistor33and a metal pad35are depicted as being formed the front side. The example transistor33is depicted as having an emitter34b, bases34a,34c, and a collector34d. Although not shown, the circuitry can also include formed passive components such as inductors, capacitors, and source, gate and drain for incorporation of planar field effect transistors (FETs) with heterojunction bipolar transistors (HBTs). Such structures can be formed by various processes performed on epitaxial layers that have been deposited on the substrate layer.

Referring to the process10ofFIG. 1, the functional wafer of block11can be tested (block12) in a number of ways prior to bonding. Such a pre-bonding test can include, for example, DC and RF tests associated with process control parameters.

Upon such testing, the wafer can be bonded to a carrier (block13). In certain implementations, such a bonding can be achieved with the carrier above the wafer. Thus,FIG. 2Cshows an example assembly of the wafer30and a carrier40(above the wafer) that can result from the bonding step13. In certain implementations, the wafer and carrier can be bonded using temporary mounting adhesives such as wax or commercially available Crystalbond™. InFIG. 2C, such an adhesive is depicted as an adhesive layer38.

In certain implementations, the carrier40can be a plate having a shape (e.g., circular) similar to the wafer it is supporting. Preferably, the carrier plate40has certain physical properties. For example, the carrier plate40can be relatively rigid for providing structural support for the wafer. In another example, the carrier plate40can be resistant to a number of chemicals and environments associated with various wafer processes. In another example, the carrier plate40can have certain desirable optical properties to facilitate a number of processes (e.g., transparency to accommodate optical alignment and inspections)

Materials having some or all of the foregoing properties can include sapphire, borosilicate (also referred to as Pyrex), quartz, and glass (e.g., SCG72).

In certain implementations, the carrier plate40can be dimensioned to be larger than the wafer30. Thus, for circular wafers, a carrier plate can also have a circular shape with a diameter that is greater than the diameter of a wafer it supports. Such a larger dimension of the carrier plate can facilitate easier handling of the mounted wafer, and thus can allow more efficient processing of areas at or near the periphery of the wafer.

Tables 1A and 1B list various example ranges of dimensions and example dimensions of some example circular-shaped carrier plates that can be utilized in the process10ofFIG. 1.

An enlarged portion39of the bonded assembly inFIG. 2Cis depicted inFIG. 2D. The bonded assembly can include the GaAs substrate layer32on which are a number of devices such as the transistor (33) and metal pad (35) as described in reference toFIG. 2B. The wafer (30) having such substrate (32) and devices (e.g., 33, 35) is depicted as being bonded to the carrier plate40via the adhesive layer38.

As shown inFIG. 2D, the substrate layer32at this stage has a thickness of d1, and the carrier plate40has a generally fixed thickness (e.g., one of the thicknesses in Table 1). Thus, the overall thickness (Tassembly) of the bonded assembly can be determined by the amount of adhesive in the layer38.

In a number of processing situations, it is preferable to provide sufficient amount of adhesive to cover the tallest feature(s) so as to yield a more uniform adhesion between the wafer and the carrier plate, and also so that such a tall feature does not directly engage the carrier plate. Thus, in the example shown inFIG. 2D, the emitter feature (34binFIG. 2B) is the tallest among the example features; and the adhesive layer38is sufficiently thick to cover such a feature and provide a relatively uninterrupted adhesion between the wafer30and the carrier plate40.

Referring to the process10ofFIG. 1, the wafer—now mounted to the carrier plate—can be thinned so as to yield a desired substrate thickness in blocks14and15. In block14, the back side of the substrate32can be ground away (e.g., via two-step grind with coarse and fine diamond-embedded grinding wheels) so as to yield an intermediate thickness-substrate (with thickness d2as shown inFIG. 2E) with a relatively rough surface. In certain implementations, such a grinding process can be performed with the bottom surface of the substrate facing downward.

In block15, the relatively rough surface can be removed so as to yield a smoother back surface for the substrate32. In certain implementations, such removal of the rough substrate surface can be achieved by an O2plasma ash process, followed by a wet etch process utilizing acid or base chemistry. Such an acid or base chemistry can include HCl, H2SO4, HNO3, H3PO4, H3COOH, NH4OH, H2O2, etc., mixed with H2O2and/or H2O. Such an etching process can provide relief from possible stress on the wafer due to the rough ground surface.

In certain implementations, the foregoing plasma ash and wet etch processes can be performed with the back side of the substrate32facing upward. Accordingly, the bonded assembly inFIG. 2Fdepicts the wafer30above the carrier plate40.FIG. 2Gshows the substrate layer32with a thinned and smoothed surface, and a corresponding thickness of d3.

By way of an example, the pre-grinding thickness (d1inFIG. 2D) of a 150 mm (also referred to as “6-inch”) GaAs substrate can be approximately 675 μm. The thickness d2(FIG. 2E) resulting from the grinding process can be in a range of approximately 102 μm to 120 μm. The ash and etching processes can remove approximately 2 μm to 20 μm of the rough surface so as to yield a thickness of approximately 100 μm. (d3inFIG. 2G). Other thicknesses are possible.

In certain situations, a desired thickness of the back-side-surface-smoothed substrate layer can be an important design parameter. Accordingly, it is desirable to be able to monitor the thinning (block14) and stress relief (block15) processes. Since it can be difficult to measure the substrate layer while the wafer is bonded to the carrier plate and being worked on, the thickness of the bonded assembly can be measured so as to allow extrapolation of the substrate layer thickness. Such a measurement can be achieved by, for example, a gas (e.g., air) back pressure measurement system that allows detection of surfaces (e.g., back side of the substrate and the “front” surface of the carrier plate) without contact.

As described in reference toFIG. 2D, the thickness (Tassembly) of the bonded assembly can be measured; and the thicknesses of the carrier plate40and the un-thinned substrate32can have known values. Thus, subsequent thinning of the bonded assembly can be attributed to the thinning of the substrate32; and the thickness of the substrate32can be estimated.

Referring to the process10ofFIG. 1, the thinned and stress-relieved wafer can undergo a through-wafer via formation process (block16).FIGS. 2H-2Jshow different stages during the formation of a via44. Such a via is described herein as being formed from the back side of the substrate32and extending through the substrate32so as to end at the example metal pad35. It will be understood that one or more features described herein can also be implemented for other deep features that may not necessarily extend all the way through the substrate. Moreover, other features (whether or not they extend through the wafer) can be formed for purposes other than providing a pathway to a metal feature on the front side.

To form an etch resist layer42that defines an etching opening43(FIG. 2H), photolithography can be utilized. Coating of a resist material on the back surface of the substrate, exposure of a mask pattern, and developing of the exposed resist coat can be achieved in known manners. In the example configuration ofFIG. 2H, the resist layer42can have a thickness in a range of about 15 μm to 20 μm.

To form a through-wafer via44(FIG. 2I) from the back surface of the substrate to the metal pad35, techniques such as dry inductively coupled plasma (ICP) etching (with chemistry such as BCl3/Cl2) can be utilized. In various implementations, a desired shaped via can be an important design parameter for facilitating proper metal coverage therein in subsequent processes.

FIG. 2Jshows the formed via44, with the resist layer42removed. To remove the resist layer42, photoresist strip solvents such as NMP (N-methyl-2-pyrrolidone) and EKC can be applied using, for example, a batch spray tool. In various implementations, proper removal of the resist material42from the substrate surface can be an important consideration for subsequent metal adhesion. To remove residue of the resist material that may remain after the solvent strip process, a plasma ash (e.g., O2) process can be applied to the back side of the wafer.

Referring to the process10ofFIG. 1, a metal layer can be formed on the back surface of the substrate32in block17.FIGS. 2K and 2Lshow examples of adhesion/seed layers and a thicker metal layer.

FIG. 2Kshows that in certain implementations, an adhesion layer45such as a nickel vanadium (NiV) layer can be formed on surfaces of the substrate's back side and the via44by, for example, sputtering. Preferably, the surfaces are cleaned (e.g., with HCl) prior to the application of NiV.FIG. 2Kalso shows that a seed layer46such as a thin gold layer can be formed on the adhesion layer45by, for example, sputtering. Such a seed layer facilitates formation of a thick metal layer47such as a thick gold layer shown inFIG. 2L. In certain implementations, the thick gold layer can be formed by a plating technique.

In certain implementations, the gold plating process can be performed after a pre-plating cleaning process (e.g., O2plasma ash and HCl cleaning). The plating can be performed to form a gold layer of about 3 μm to 6 μm to facilitate the foregoing electrical connectivity and heat transfer functionalities. The plated surface can undergo a post-plating cleaning process (e.g., O2plasma ash).

The metal layer formed in the foregoing manner forms a back side metal plane that is electrically connected to the metal pad35on the front side. Such a connection can provide a robust electrical reference (e.g., ground potential) for the metal pad35. Such a connection can also provide an efficient pathway for conduction of heat between the back side metal plane and the metal pad35.

Thus, one can see that the integrity of the metal layer in the via44and how it is connected to the metal pad35and the back side metal plane can be important factors for the performance of various devices on the wafer. Accordingly, it is desirable to have the metal layer formation be implemented in an effective manner. More particularly, it is desirable to provide an effective metal layer formation in features such as vias that may be less accessible.

Referring to the process10ofFIG. 1, the wafer having a metal layer formed on its back side can undergo a street formation process (block18).FIGS. 2M-2Oshow different stages during the formation of a street50. Such a street is described herein as being formed from the back side of the wafer and extending through the metal layer52to facilitate subsequent singulation of dies. It will be understood that one or more features described herein can also be implemented for other street-like features on or near the back surface of the wafer. Moreover, other street-like features can be formed for purposes other than to facilitate the singulation process.

To form an etch resist layer48that defines an etching opening49(FIG. 2M), photolithography can be utilized. Coating of a resist material on the back surface of the substrate, exposure of a mask pattern, and developing of the exposed resist coat can be achieved in known manners.

To form a street50(FIG. 2N) through the metal layer52, techniques such as wet etching (with chemistry such as potassium iodide) can be utilized. A pre-etching cleaning process (e.g., O2plasma ash) can be performed prior to the etching process. In various implementations, the thickness of the resist48and how such a resist is applied to the back side of the wafer can be important considerations to prevent certain undesirable effects, such as via rings and undesired etching of via rim during the etch process.

FIG. 2Oshows the formed street50, with the resist layer48removed. To remove the resist layer48, photoresist strip solvents such as NMP (N-methyl-2-pyrrolidone) can be applied using, for example, a batch spray tool. To remove residue of the resist material that may remain after the solvent strip process, a plasma ash (e.g., O2) process can be applied to the back side of the wafer.

In the example back-side wafer process described in reference toFIGS. 1 and 2, the street (50) formation and removal of the resist (48) yields a wafer that no longer needs to be mounted to a carrier plate. Thus, referring to the process10ofFIG. 1, the wafer is debonded or separated from the carrier plate in block19.FIGS. 2P-2Rshow different stages of the separation and cleaning of the wafer30.

In certain implementations, separation of the wafer30from the carrier plate40can be performed with the wafer30below the carrier plate40(FIG. 2P). To separate the wafer30from the carrier plate40, the adhesive layer38can be heated to reduce the bonding property of the adhesive. For the example Crystalbond™ adhesive, an elevated temperature to a range of about 130° C. to 170° C. can melt the adhesive to facilitate an easier separation of the wafer30from the carrier plate40. Some form of mechanical force can be applied to the wafer30, the carrier plate40, or some combination thereof, to achieve such separation (arrow53inFIG. 2P). In various implementations, achieving such a separation of the wafer with reduced likelihood of scratches and cracks on the wafer can be an important process parameter for facilitating a high yield of good dies.

InFIGS. 2P and 2Q, the adhesive layer38is depicted as remaining with the wafer30instead of the carrier plate40. It will be understood that some adhesive may remain with the carrier plate40.

FIG. 2Rshows the adhesive38removed from the front side of the wafer30. The adhesive can be removed by a cleaning solution (e.g., acetone), and remaining residues can be further removed by, for example, a plasma ash (e.g., O2) process.

Referring to the process10ofFIG. 1, the debonded wafer of block19can be tested (block20) in a number of ways prior to singulation. Such a post-debonding test can include, for example, resistance of the metal interconnect formed on the through-wafer via using process control parameters on the front side of the wafer. Other tests can address quality control associated with various processes, such as quality of the through-wafer via etch, seed layer deposition, and gold plating.

Referring to the process10ofFIG. 1, the tested wafer can be cut to yield a number of dies (block21). In certain implementations, at least some of the streets (50) formed in block18can facilitate the cutting process.FIG. 2Sshows cuts61being made along the streets50so as to separate an array of dies60into individual dies. Such a cutting process can be achieved by, for example, a diamond scribe and roller break, saw or a laser.

In the context of laser cutting,FIG. 2Tshows an effect on the edges of adjacent dies60cut by a laser. As the laser makes the cut61, a rough edge feature62(commonly referred to as recast) typically forms. Presence of such a recast can increase the likelihood of formation of a crack therein and propagating into the functional part of the corresponding die.

Thus, referring to the process10inFIG. 1, a recast etch process using acid and/or base chemistry (e.g., similar to the examples described in reference to block15) can be performed in block22. Such etching of the recast feature62and defects formed by the recast, increases the die strength and reduces the likelihood of die crack failures (FIG. 2U).

Referring to the process10ofFIG. 1, the recast etched dies (FIG. 2V) can be further inspected and subsequently be packaged.

As described herein in reference toFIGS. 1 and 2, some operations in the process10can benefit from having a wafer temporarily bonded to a carrier plate. Once such operations are completed, the wafer can be removed or debonded from the carrier plate.FIGS. 3-7show by way of examples a bonding apparatus having a securing mechanism that reduces the likelihood of unwanted debris or small objects being introduced into an area where the bonding process occurs.

It will be understood that one or more features associated with debonding devices and methodologies can be implemented in the example through-wafer via process described in reference toFIGS. 1 and 2, as well as in other processing situations. It will also be understood that one or more features associated with debonding devices and methodologies can be implemented in different types of semiconductor-based wafers, including but not limited to those formed from semiconductor materials such as groups IV, III-V, II-VI, I-VII, IV-VI, V-VI, II-V; oxides; layered semiconductors; magnetic semiconductors; organic semiconductors; charge-transfer complexes; and other semiconductors. Further, some of the features described herein can also be implemented in situations involving separation of non-semiconductor-based wafers from another structure.

Various wafer processing operations can be performed in controlled environments such as those associated with various clean rooms. Among other controlled environmental factors, “cleanliness” of a clean room greatly reduces the concentration of small particles (e.g., dust particles, lint, etc.) circulating in the air so as to reduce the likelihood of such particles settling on wafers. Detrimental effects of such particles on wafers are known.

FIGS. 3A and 3Bshow side and plan views of a bonding apparatus100having a lower member102and an upper member104. The lower member102and/or the upper member104can define a bonding chamber106where a wafer (not shown) can undergo a bonding process with a carrier plate (not shown). In some situations, such a bonding process can involve curing of an adhesive that has already been applied (e.g., spun on). Such a curing process can be facilitated by an application of heat. The bonding apparatus100can be configured appropriately so as to yield a bonded assembly of wafer and carrier plate where the wafer and the carrier plate are substantially parallel.

The upper member104can be moved (depicted as an arrow124) so as to allow it to open and close the bonding chamber106. The upper member104can be opened to allow loading of the uncured wafer-carrier assembly and unloading of the cured wafer-carrier assembly. The upper member104can be closed facilitate the curing process.

The opening and closing of the upper member104can be facilitated by a handle108that is attached to the upper member104by, for example, one or more screws110. The handle108can also be attached to a hinge114by, for example, one or more screws112. The hinge114can be coupled to a support member118through a pivot116so at to allow the upper member104to rotate between its open and closed positions about the pivot116.

When in the closed position, the upper member can be secured to the lower member by a number of screws120. In the example shown inFIG. 3B, four of such screws (120a-120d) are depicted as being distributed circumferentially so as to provide a distributed securing force. As shown inFIG. 3A, each of the screws120can include a threaded portion122that extends through the upper member104to engage a portion of the lower member102, thereby allowing the screw to be tightened to secure the upper member104to the lower member102.

Tightening and removing of the screws120involve surface engagements between the threaded portions122of the screws120and their respective matching threads on the lower member102. Consequently, such surface engagements can result in small metal and other particles being generated and falling or somehow being introduced into the bonding chamber106. Some of such particles can become undesirably attached to a wafer being bonded therein.

In the example shown inFIGS. 3A and 3B, the screws120are depicted as extending into the bonding chamber106. However, even if the screws120do not invade the bonding chamber106, they need to extend through the mating surfaces of the upper and lower members104,102. Consequently, any undesirable particles resulting from the thread engagements can collect on either or both of the mating surfaces, and move into the bonding chamber106during the opening and closing operations.

FIGS. 4-7show various examples of a securing mechanism that can secure upper and lower members220,222of a bonding apparatus202in a manner where the likelihood of introduction of undesirable particles from the securing mechanism into the bonding chamber is reduced or substantially eliminated. In certain implementations, such a reduction can be achieved by configuring the securing mechanism to reduce the amount of undesirable particles being generated and/or to provide the securing force without having to pull the upper and lower members220,222together by a structure that extends through one of the members (e.g., upper member220) into the other (e.g., lower member222).

FIG. 4shows an example bonding station200having a number of the wafer bonding apparatus202. In certain embodiments, the upper member220, the lower member222, and the handle224configured to operate in manners similar to those (104,102,108) described in reference toFIGS. 3A and 3B. In certain embodiments, the upper member220can be secured to the lower member222by one or more securing mechanisms230as described herein.

FIG. 4shows that the example bonding station200can include a base (within the housing208) that supports the lower members222. The base can also be mechanically coupled to support legs204to facilitate positioning of the station200on a surface206. The station200can also include a control component210for controlling various operating parameters such as temperature for curing of the adhesive, gas pressure for applying pressing the wafer and carrier plate in a controlled manner, and vacuum for holding the wafer-carrier assembly during the curing process. InFIG. 4, a vacuum handling wand212is also shown. Such a device can be used to manipulate the wafer-carrier assembly during loading and unloading operations.

In certain embodiments, each bonding apparatus202can include one or more securing mechanisms230. In the example shown, there are two of such mechanisms230a,230bfor each bonding apparatus202. In other embodiments, the number of such mechanisms can also be greater than or less than two.

FIGS. 5A and 5Bshow the bonding apparatus202with (FIG. 5B) and without (FIG. 5A) a wafer-carrier assembly260in the bonding chamber. With the upper member220in its upper position (e.g., rotated open about a pivot246), one can see that the bonding chamber can include a platform surface256dimensioned to receive the wafer-carrier assembly260. The surface256can define a vacuum aperture258in communication with a vacuum device (not shown) and configured to provide a suction hold of the wafer-carrier assembly260. Such a vacuum aperture258can also facilitate removal of gas pockets that may have formed between the surface256and the wafer-carrier assembly260.

The upper member220can include a pneumatic diaphragm244configured to provide a wide pushing force on the wafer-carrier assembly260during the curing process. The diaphragm244can be actuated by pressurized gas delivered through an aperture242in communication with a region behind the diaphragm244. The aperture242on the upper member220can be in communication with a ring space254defined between inner and outer sealing rings252,250and a pressure input aperture248. Thus, when the upper member220is lowered onto the lower member222, the upper member's engaging surface240engages with the sealing rings252,250to separate the pressure system (including the ring space254) from the vacuum system of the bonding chamber and from the outside.

Referring toFIG. 5A, the securing mechanism230can be secured to the base (not shown) by a support bar232.

InFIG. 6A, the upper member220has been lowered to its closed position so as to engage the lower member222. Such closing and opening operations can be facilitated by the handle224attached to the upper member220by one or more fasteners such as screws270. The handle224is depicted as being mounted to a hinge by one or more fasteners such as screws272.

InFIG. 6A, the upper member220has been lowered but not secured by the securing mechanisms230a,230b. InFIG. 6B, the securing mechanisms230a,230bare in their secured positions.

In certain implementations, each of the securing mechanism230can include a base300that is mounted on the support bar232in a manner that allows the securing mechanism230to rotate with the support bar232(about axis of the support bar232) to facilitate the opening and closing of the upper member220. Once the securing mechanism230in rotated to allow engagement with the upper member220(230binFIG. 6A), a push rod280can be swung down (arrow282) so that its engagement end284can engage the upper surface274of the upper member220. Upon engagement, the push rod280can be pushed further against the upper surface274and generally maintained there so as to secure the upper member220against the lower member222.

In certain embodiments, the securing mechanism230can include a support beam290that is pivotably mounted (292) to the base300(of the securing mechanism230). The push rod280can be mounted at a distance from the pivot292so that the pivot292facilitates the movement282of the push rod towards and away from the upper surface274of the upper member220. In certain embodiments, the push rod's orientation relative to the support beam290can be approximately perpendicular; however, the angle between the two can be greater or less than 90 degrees to facilitate an appropriate securing engagement of the push rod280with the upper member220.

In certain embodiments, the distance between the push rod's engagement end284and its mounting location on the support beam290can be adjusted to facilitate, for example, the amount of push force applied to the upper member. In the example shown, the push rod280can include a threaded portion so as to be mounted to the support beam290by threaded nuts286. Accordingly, the push rod280can be moved relative to the support beam290by loosening and tightening the nuts286appropriately.

In certain embodiments, the location where the push rod280is mounted (to the support beam290) can be selected so that when secured, the push rod280pushes on a selected location (e.g., a peripheral portion) of the upper surface274. In the example shown inFIGS. 6A and 6B, the mounting location of the push rod280along the support beam290can be adjusted by loosening one or more of the nuts286, sliding the mounting to a desired location on the support beam290, and tightening the nut(s)286. Thus, as shown inFIG. 6B, two such pushing forces (provided by the two example push rods) on the upper member220can provide a distributed securing force on the upper member220.

In certain embodiments, a plurality of such securing mechanisms230can be distributed generally uniformly about the upper member220. In the example shown, the two securing mechanisms230are depicted as being distributed with about 180-degree separation.

In certain embodiments, the securing mechanism230can include a locking handle294that is configured to push the push rod280(through the support member290) into its securing position and lock the securing mechanism230in such a position. To provide such a feature, the locking handle294can be pivotably mounted (296) to the base and include a locking mechanism (e.g., a camming action) that locks the securing mechanism230by pushing the handle294towards the center of the upper member220after the placement of the push rod280on the upper member220. Unlocking of the securing mechanism230can be achieved by pushing the handle294away from the center of the upper member220to thereby allow the push rod280to be moved away from the upper member220.

In certain implementations, a securing mechanism having some or all of the foregoing features can be configured to provide an amount of force that results in an acceptable sealing functionality of the seals250,252. On the other hand, the amount of force is preferably less than an amount that would crush the seal(s) and possibly damage the wafer-carrier assembly.

In certain implementations, the amount of force can also be selected so to overcome the tendency of the upper member220to separate from the lower member222as the diaphragm244pushes on the wafer-carrier assembly.

FIG. 7shows the upper member220in its open position after the completion of a bonding process. The bonded wafer-carrier assembly260is depicted as being removed from the lower member222by the vacuum handling device212previously referred to inFIG. 4.

In the non-limiting example described herein, the securing mechanism is configured to operate as a clamp or a clamp-like device to provide a pushing force on the upper member (also referred to as a lid herein). It will be appreciated that a number of other designs can also be implemented to provide one or more functionalities as described herein.

As described herein, the lid can include first and second opposing sides, with the first side dimensioned to engage a receiving side of the lower member (also referred to as a base member herein) base member when the lid is in the closed position, and with the second side separated from the first side by a substantially solid plate. Such a separation of the first and second sides of the lid by the plate reduces the likelihood that undesirable particles originating from the operation of the securing mechanism will be introduced to the first side of the lid and/or the bonding chamber.