Patent Description:
In particular, this disclosure relates to methods for placing a semiconductor device to another substrate. In particular this disclosure relates to methods for placing one or more arbitrarily shaped semiconductor devices to another substrate.

Semiconductor devices, such as Integrated Circuits and micro-electromechanical devices (MEMS), are manufactured using semiconductor process technology enabling highly accurate alignment of individual patterns needed to create a semiconductor device. Afterwards, these devices can be transferred to and placed onto another substrate, e.g. for post-processing or for chip packaging. Typically they are placed individually using a pick-and-place tool.

Although advanced pick-and-place tools have good alignment capabilities, their accuracy of placing the individual devices is considerably less than the accuracy obtained with state-of-the-art lithographic tools used for fabrication of the semiconductor devices. Consequently, in postprocessing or packaging the transferred semiconductor devices, one has to take into account this reduced placement accuracy. Devices transferred to a common substrate may be misaligned towards each-other. In addition, features patterned on a transferred device, during a postprocessing or packaging process, must be sufficiently large to avoid misalignment towards the transferred device. In case narrow patterns on a transferred device are required, device by device processing of such narrow pattern is needed to ensure an acceptable alignment of each narrow pattern to the corresponding transferred device. As parallel processing is not feasible, this will result in a low fabrication speed.

Pick-and-place tools are designed to handle the transfer of rectangular shaped semiconductor devices, obtained by dicing the semiconductor substrate, used to manufacture these devices, into rectangular chips. Semiconductor devices having an arbitrarily shape cannot be diced with conventional dicing tools.

Hence, there is a need to place arbitrarily shaped chips with improved accuracy and throughput compared to state of the art. Preferably this transfer is executed using conventional postprocessing equipment.

<CIT> and <CIT> disclose a method for handling an intermediate rectangular chip, mounting it onto a carrier substrate and packaging it. After mounting and packaging (including e.g. wire bonding and encapsulating), this intermediate chip is separated into smaller chips (<NUM>-<NUM> in <FIG> of D1; <NUM> in <FIG> of D2).

<CIT> and <CIT> disclose a method for singulating chips with an irregular shape by directly etching a wafer (without any intermediate singulated chip).

The present disclosure will be described with respect to particular embodiments and with reference to certain drawings but the disclosure is not limited thereto but only by the claims. The dimensions and the relative dimensions do not correspond to actual reductions to practice of the disclosure.

A method is disclosed for placing on a carrier substrate a semiconductor device, the method being defined by claim <NUM> and comprising: providing a semiconductor substrate comprising a rectangular shaped assist chip which comprises at least one semiconductor device surrounded by a metal-free border, dicing the semiconductor substrate to singulate the rectangular shaped assist chip, providing a carrier substrate having adhesive thereon, transferring to and placing on the carrier substrate the rectangular shaped assist chip, thereby contacting the adhesive with the assist chip at least at the location of the semiconductor device, and; singulating the semiconductor device, while remaining attached to the carrier substrate by the adhesive, by removing the part of rectangular shaped assist chip other than the semiconductor device. This at least one semiconductor device has a shape other than rectangular. More than on semiconductor device, of any shape, can be contained by the assist chip. Preferably the carrier substrate contains markers for aligning the assist chip when being placed thereon. On the carrier substrate a support may be formed at each location where a semiconductor device is to be placed and the adhesive is then provided on each support. While the semiconductor device remains attached to the carrier substrate by the adhesive, the semiconductor device can be post-processed.

It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the disclosure described herein are capable of operation in other orientations than described or illustrated herein.

It means that with respect to the present disclosure, the only relevant components of the device are A and B.

Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Similarly it should be appreciated that in the description of exemplary embodiments of the disclosure, various features of the disclosure are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects.

In the description with chip is meant a piece of semiconductor material, in and/or on which structures can be defined using semiconductor process technology. With semiconductor device is meant the combination of patterned and un-patterned layers forming a functional structure. Semiconductor process technology refers to the state-of-art technology of integrated processing whereby layers are formed on a semiconductor substrate to form a semiconductor device. Post-processing refers to the processing of semiconductor devices after they have been formed using semiconductor technology processing. Post-processing is done on the diced chip containing the semiconductor device. Post-processing may refer to packaging the diced chip or to forming additional patterned and un-patterned layers on the diced chips, optionally connecting diced chips.

A method is disclosed for transferring to and placing on a substrate a semiconductor device thereby maintaining the alignment accuracy of conventional semiconductor tools used to manufacture these semiconductor devices. Thanks to this alignment accurancy, during postprocessing, simultaneously lithographic patterning of the transferred semiconductor devices is possible, with even increased accuracy over state-of-the-art technology. Moreover, this method is not limited to rectangular shaped semiconductor devices, but enables transfer, placing and further processing on semiconductor devices having a random shape. This method enables more then one semiconductor device to be transferred in parallel to a substrate.

On a semiconductor substrate (<NUM>), within the boundary of a rectangular shaped chip (<NUM>), multiple semiconductor devices (<NUM>) are formed in parallel using conventional semiconductor processing.

These semiconductor devices (<NUM>) can be Integrated Circuits, micro-electromechanical devices (MEMS) or a combination thereof. For Integrated Circuits active and/or passive components are created in the so-called Front-End-Of-Line, whereby these components are electrically connected in the so-called Back-End-Of-Line formed thereupon. The smaller semiconductor devices (<NUM>) are positioned relatively to each-other on the predetermined position they need to have on the common substrate to which they (<NUM>) will be transferred to and placed on after dicing. The semiconductor devices (<NUM>) are hence in a fixed positional relationship towards each-other. These semiconductor devices (<NUM>) are rectangular in shape. Each semiconductor device (<NUM>) is surrounded by a, preferably small, metal-free border (<NUM>) outlining the semiconductor device (<NUM>), as indicated in <FIG> by the dotted line. As will be disclosed in subsequent paragraphs, the absence of metal in the border (<NUM>) easies removal of the material present in this border (<NUM>) when separating the multiple semiconductor devices (<NUM>) after transfer thereof. During the semiconductor processing of the substrate (<NUM>), care must be taken to avoid the presence of metal in this border (<NUM>). Typically, this border (<NUM>) has a width in the range of <NUM> to <NUM> micrometer (um). Although in <FIG>, the 'assist chip' (<NUM>) only contains two semiconductor devices (<NUM>), the disclosure is not limited thereto.

The rectangular shaped chip (<NUM>) is referred to as 'assist chip'. As can be seen in <FIG>, only part of the area of the 'assist chip' (<NUM>) will be taken up by the semiconductor devices (<NUM>). The remaining area of the 'assist chip' (<NUM>) outside the border (<NUM>) is referred to as 'semiconductor frame' (<NUM>). Within this frame (<NUM>) additional patterns (not shown), such as dummy patterns, can be present as may be necessitated for correct semiconductor processing of the semiconductor devices (<NUM>). Also test structures and/or alignment patterns may be present in the frame (<NUM>). Preferably the area of the 'semiconductor frame' (<NUM>) should be as small as possible to increase the yield of the semiconductor processing. The minimal spacing between the semiconductor devices (<NUM>) is inter alia also determined by the area needed to package the semiconductor devices (<NUM>). As seen in <FIG>, the semiconductor substrate (<NUM>) contains a pattern of rectangular shaped chips (<NUM>) separated by conventional scribe lines (<NUM>). The semiconductor substrate (<NUM>) will be diced into individual chips (<NUM>) along these scribe lines (<NUM>), whereby each chip (<NUM>) corresponds to an 'assist chip' (<NUM>) comprising multiple semiconductor devices (<NUM>). Optionally, as illustrated by the cross-section A-A of by <FIG>, the material (<NUM>), typically Back-End-Of-Line material, in the border (<NUM>) is removed down to the semiconductor substrate (<NUM>) thereby forming corresponding trenches surrounding each semiconductor device (<NUM>). This removal can be done using conventional lithographic patterning of the border (<NUM>). If no metal patterns are included in the frame (<NUM>), e.g. if the semiconductor devices (<NUM>) are MEMS devices, then all material in the frame (<NUM>) on top of the semiconductor substrate (<NUM>) can be removed as illustrated by the cross-section A-A of <FIG>.

The semiconductor substrate (<NUM>) is now ready to be diced. Using conventional dicing processes, each rectangular 'assist chip' (<NUM>) is singulated. Optionally the semiconductor substrate (<NUM>) can be further thinned, e.g. by grinding, to reduce the overall thickness of the diced chip.

A carrier substrate (<NUM>) is provided to which a singulated 'assist chip' (<NUM>) is transferred and placed upon using conventional pick-and-place tools. Preferably, on this carrier substrate (<NUM>) alignment marks (<NUM>) are provided allowing accurate positioning of the 'assist chip' (<NUM>), as illustrated in <FIG>. Typically these alignment markers (<NUM>) are formed in an optically visible layer (<NUM>) present on the substrate (<NUM>). The dotted lines in <FIG> indicates the position of the 'assist chip' (<NUM>). The dot-point lines in <FIG> and the semiconductor devices (<NUM>) when placed on the carrier substrate (<NUM>).

The 'assist chip' is fixed, e.g. face-up, directly on the carrier substrate (<NUM>) by providing adhesive (<NUM>) on the carrier substrate (<NUM>). If this adhesive is only provided at locations corresponding to the position of the semiconductor devices (<NUM>) when being placed on the carrier substrate (<NUM>), then these alignment markers (<NUM>) may be required to accuraterely align the 'assist chip' (<NUM>), and hence the semiconductor devices (<NUM>), to the locations containing the adhesive (<NUM>). As shown in <FIG>, this adhesive (<NUM>) is applied within the dash-dotted lines indicating the future location of the semiconductor devices (<NUM>). Restricting the adhesive to these locations, may be necessitated by the fact that the adhesive (<NUM>) is difficult to remove from the carrier substrate (<NUM>), in parrticular after curing of the adhesive, or the adhesive may not be exposed to further processing after placing the 'assist chip' (<NUM>). Otherwise, the adhesive can be applied over a sufficiently large area in which the 'assist chip' (<NUM>) can be placed thereby adhering to the carrier substrate (<NUM>). Depending on the required alignment accuracy, alignment markers (<NUM>) may still be needed, even if the whole of the 'assist chip' (<NUM>) is adhered to the carrier substrate (<NUM>).

Alternatively, a support layer (<NUM>) (not shown) is formed on the carrier substrate (<NUM>). This support layer (<NUM>) is patterned to form a support (<NUM>) at locations corresponding to the position of the semiconductor devices (<NUM>) when placed in face-up direction on the carrier substrate (<NUM>). As illustrated in <FIG> this support preferably extends beyond the footprint of the semiconductor devices (<NUM>) indicated by the dot-point lines. Thanks to this extension, some misalignment of the 'assist chip' (<NUM>) when being placed on the carrier substrate (<NUM>), can be tolerated. Optionally the alignment marks (<NUM>) can be patterned in the support layer (<NUM>) as well, in which case layer (<NUM>) may become obsolete. On the supports (<NUM>) adhesive (<NUM>) is applied, either as dots as shown in <FIG>, or uniform over the surface of the support (<NUM>).

An advantage of the method disclosed is that even for thinned 'assist chips' (<NUM>), e.g. less than <NUM> micrometer, typcially less than <NUM> micrometer, excess adhesive may stay underneath the 'assist chip' (<NUM>) when applied locally. Even if such excess adhesive would extend above the height of the 'assist chip' (<NUM>) when placed on the carier substrate (<NUM>), appropriate dimension of the 'assist chip' (<NUM>), i.e. providing sufficient margin between the border of the 'assist chip' (<NUM>) and the border (<NUM>) surrounding the semiconductor device (<NUM>) will prevent the adhesive (<NUM>) from reaching the semiconductor device (<NUM>).

It is also possible to place to assist chip (<NUM>) faced-down, hence with the metal bondpads facing towards the carrier substrate (<NUM>). In this case, the substrate (<NUM>) should carry the suitable metallization patterns prior to chip placement, to ensure that the correct electrical interconnections are realized between a metal bondpad of a device (<NUM>) and the metallization pattern. The placement can be done by using i.e. flip-chip technology, to realize a conductive connection between the metallization pattern and the bondpads of the semiconductor devices (<NUM>), while good adhesion is realized between the semiconductor devices (<NUM>) and the carrier substrate (<NUM>). This is further illustrated by <FIG>,<FIG> and <FIG>.

To the carrier substrate (<NUM>), the singulated 'assist chip' (<NUM>) is transferred and placed upon, thereby making physical contact with the adhesive (<NUM>). Thanks to the alignment markers (<NUM>) present, the 'assist chip' (<NUM>) can be accurately positioned on the carrier substrate (<NUM>) ensuring the desired position of the semiconductor devices (<NUM>) towards the carrier substrate (<NUM>) while maintaining their relative position. Thanks to the rectangular shape of the 'assist chip', conventional pick-and-place tools can easily be used for this transfer, alignment and placement. <FIG> illustrate the embodiment where the adhesive (<NUM>) is applied directly to the carrier substrate (<NUM>).

<FIG> illustrate the embodiment whereby a support (<NUM>) is present on the carrier substrate (<NUM>) prior to applying the adhesive (<NUM>). After placing the 'assist chip' (<NUM>), the adhesive (<NUM>) is cured to ensure adhesion between the semiconductor substrate (<NUM>) and the carrier substrate (<NUM>) at the location of the semiconductor devices (<NUM>).

Once the semiconductor devices (<NUM>) are adhered to the carrier substrate (<NUM>) by the adhesive (<NUM>), these semiconductor devices (<NUM>) can also be singulated. A photoresist layer (<NUM>) is applied over the carrier substrate (<NUM>) as shown in <FIG> and <FIG>. Due the spacing between the 'assist chip' (<NUM>) and the carrier substrate (<NUM>) resist may flow underneath the 'assist chip' (<NUM>). This photoresist layer (<NUM>) is then patterned to remain on the location of the semiconductor devices (<NUM>) while the frame (<NUM>) is uncovered. Traces of photoresist may remain underneath the 'assist chip' (<NUM>), at least near the edge thereof. The pattern of the photoresist layer (<NUM>) may extend over the border of the semiconductor device (<NUM>) to ensure that the semiconductor device (<NUM>) remains protected.

<FIG> and <FIG> illustrate the embodiment where the adhesive (<NUM>) is applied directly to the carrier substrate (<NUM>). The photoresist layer (<NUM>) is patterned whereby traces of photoresist remain underneath the 'assist chip' (<NUM>).

<FIG> and <FIG> illustrate the embodiment whereby a support (<NUM>) is present on the carrier substrate (<NUM>) prior to applying the adhesive (<NUM>). The photoresist layer (<NUM>) is patterned whereby traces of photoresist remain underneath the 'assist chip' (<NUM>).

As the semiconductor devices (<NUM>) are protected by the patterned photoresist layer (<NUM>), the frame (<NUM>) can be removed, preferably if no metal is present. After removal of the frame (<NUM>), the photoresist (<NUM>) on the semiconductor devices (<NUM>), and if present on the carrier substrate (<NUM>) is removed. Attached to and aligned to carrier substrate (<NUM>), the semiconductor devices (<NUM>) remain in their relative position as defined during the processing of the semiconductor substrate (<NUM>). In <FIG> it was shown that either the metal-free border (c) or the metal-free border (d) was removed down to the level of the semiconductor substrate (<NUM>). This removal process can be executed on wafer level and is more efficient. After placing the diced chip (<NUM>) on the carrier substrate (<NUM>), only the semiconductor substrate part of the frame (<NUM>) is to be removed to singulate the semiconductor devices (<NUM>).

<FIG> illustrate the embodiment where the adhesive (<NUM>) is applied directly to the carrier substrate (<NUM>).

<FIG> illustrate the embodiment whereby a support (<NUM>) is present on the carrier substrate (<NUM>) prior to applying the adhesive (<NUM>).

Instead of singulating the semiconductor devices (<NUM>) by removing the complete frame (<NUM>), preferably only the metal-free border (<NUM>) can be removed. A photoresist layer (<NUM>) is applied over the carrier substrate (<NUM>) as shown in <FIG> and <FIG>. Due the spacing between the 'assist chip' (<NUM>) and the carrier substrate (<NUM>) resist may flow underneath the 'assist chip' (<NUM>). This photoresist layer (<NUM>) is then patterned to remain outside the area of the border (<NUM>) thereby creating trenches (<NUM>) in the photoresist layer (<NUM>) surrounding the semiconductor devices (<NUM>). Traces of photoresist may remain underneath the 'assist chip' (<NUM>), at least near the edge thereof. The pattern of the photoresist layer (<NUM>) may extend over the border of the semiconductor device (<NUM>) to ensure that the semiconductor device (<NUM>) remains protected. Then the material of the border (<NUM>) is etched. The part of the frame (<NUM>) covered by the photoresist pattern (<NUM>) remains. After the etch step, the photoresist on top of the semiconductor devices (<NUM>) and of the remaining frame (<NUM>) is removed, thereby exposing the remaining part of the frame (<NUM>). When removing the traces of the photoresist (<NUM>) that were present underneath the 'assist chip' (<NUM>), this remainder of the frame (<NUM>) will be lifted-off from the carrier substrate (<NUM>). This again results in the configuration illustrated by <FIG> and <FIG>, as the semiconductor devices (<NUM>) remain attached by the adhesive (<NUM>) during this photoresist (<NUM>) removal process. Attached to and aligned to carrier substrate (<NUM>), the semiconductor devices (<NUM>) remain in their relative position as defined during the processing of the semiconductor substrate (<NUM>).

The semiconductor devices (<NUM>) can now be further processed, as they remain in their relative position as defined accurately during the processing of the semiconductor substrate (<NUM>), while being attached and accurately aligned to carrier substrate (<NUM>). This allows post-processing of these semiconductor devices (<NUM>), even when small patterns are to be formed upon these semiconductor devices (<NUM>), e.g. when parts of the semiconductor devices (<NUM>) need to be connected with each-other or with other devices present on or to be formed on the carrier substrate (<NUM>).

In the figures <FIG> used to illustrate the methods of this disclosure, the semiconductor devices (<NUM>) were of equal shape and size. This is not a requirement. As already indicated above, the methods according this disclosure, allow any shape and size of the semiconductor devices (<NUM>) contained within the boundary of the 'assist chip' (<NUM>). Within one 'assist chip' (<NUM>) one can design multiple semiconductor devices (<NUM>), each having a different layout, shape and size. After transferring and singulating these semiconductor devices (<NUM>), as disclosed above, one can create any desired connection between singulated semiconductor devices (<NUM>). This may result, after packaging, in a single system containing multiple arbitrarily shaped semiconductor devices, accurately aligned to each-other with the desired, small size, interconnect pattern.

<FIG>, <FIG> and <FIG> illustrate the manufacturing of such a system, for the situation of face-up chip placement. <FIG> shows an 'assist chip' (<NUM>), counting <NUM> semiconductor devices (<NUM>), after being transferred to and attached to the carrier substrate (<NUM>). Two types of semiconductor devices, identified as square or triangle, are present in the 'assist chip' (<NUM>). The devices (<NUM>) are ready to be singulated. <FIG> shows the result after singulation of the semiconductor devices (<NUM>) by removing the frame (<NUM>). <FIG> shows, after further processing, how these devices (<NUM>) are connected in pairs to yield a final system, containing <NUM> different semiconductor devices (<NUM>) connected to each-other and having an connection pattern (<NUM>) to access these semiconductor devices (<NUM>) from outside. Here the connection pattern (<NUM>) is formed after the transfer of the 'assist ship '<NUM>' and the singulation of the semiconductor devices (<NUM>).

<FIG>, <FIG> and <FIG> illustrate the manufacturing of such a system, for the situation of face-down chip placement. <FIG> shows the carrier substrate (<NUM>) prepared for face-down chip placement. The substrate contains the alignment marks (<NUM>) and the required metallization pattern for the final system. <FIG> shows an 'assist chip' (<NUM>), counting <NUM> semiconductor devices (<NUM>), after being transferred faced-down and attached to the carrier substrate (<NUM>). Two types of semiconductor devices, identified as square or triangle, are present in the 'assist chip' (<NUM>). The devices (<NUM>) are ready to be singulated. <FIG> shows the result after singulation of the semiconductor devices (<NUM>) by removing the frame (<NUM>), and after further processing to define the final system, containing <NUM> different semiconductor devices (<NUM>) connected to each-other and having an connection pattern to access these semiconductor devices (<NUM>) from outside. Here the connection pattern (<NUM>) is formed after the transfer of the 'assist ship '<NUM>' and the singulation of the semiconductor devices (<NUM>).

In the foregoing paragraphs, a rectangular shaped chip (<NUM>) comprising multiple semiconductor devices (<NUM>) was manufactured on a semiconductor substrate (<NUM>). The disclosed method for transferring and placing the rectangular shaped chip (<NUM>) can also be applied if the 'assist chip' only contains semiconductor device (<NUM>) having a shape other than rectangular. Such arbitrarily shaped semiconductor device (<NUM>) can be transferred and placed using conventional pick-and-place tools. After removing the frame, the singulated semiconductor device (<NUM>) remains attached to the carrier substrate (<NUM>) and is ready for further processing.

Claim 1:
A method for placing on a carrier substrate (<NUM>) a semiconductor device (<NUM>), the method comprising:
- providing a semiconductor substrate (<NUM>) comprising a rectangular shaped assist chip (<NUM>), bordered by scribe lines (<NUM>), which assist chip (<NUM>) comprises at least one semiconductor device (<NUM>);
- dicing the semiconductor substrate (<NUM>) along all scribe lines to singulate the rectangular shaped assist chip (<NUM>);
- providing a carrier substrate (<NUM>);
- transferring to and placing on the carrier substrate (<NUM>) the rectangular shaped assist chip (<NUM>); and
- singulating the at least one semiconductor device (<NUM>), while remaining attached to the carrier substrate (<NUM>), by removing the part of the rectangular shaped assist chip (<NUM>) other than the at least one semiconductor device (<NUM>),
wherein an adhesive (<NUM>) is applied on the carrier substrate (<NUM>);
wherein placing the rectangular shaped assist chip (<NUM>) on the carrier substrate (<NUM>) comprises making physical contact between the assist chip (<NUM>) and the adhesive (<NUM>) at least at a location of the at least one semiconductor device (<NUM>);
wherein the at least one semiconductor device (<NUM>) is surrounded by a metal-free border (<NUM>) outlining the semiconductor device (<NUM>);
wherein singulating the at least one semiconductor device (<NUM>) comprises etching the metal-free border (<NUM>), and
wherein at least one semiconductor device (<NUM>) has a shape other than rectangular.